CRISv32: Rewrite of synchronous serial port driver
authorJesper Nilsson <jespern@axis.com>
Tue, 7 Oct 2014 11:40:08 +0000 (13:40 +0200)
committerJesper Nilsson <jespern@axis.com>
Fri, 19 Dec 2014 23:05:04 +0000 (00:05 +0100)
Make driver possible to load as a module and try to handle
locking better.

Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>
arch/cris/arch-v32/drivers/sync_serial.c

index 5a14913..08a313f 100644 (file)
@@ -1,8 +1,7 @@
 /*
- * Simple synchronous serial port driver for ETRAX FS and Artpec-3.
- *
- * Copyright (c) 2005 Axis Communications AB
+ * Simple synchronous serial port driver for ETRAX FS and ARTPEC-3.
  *
+ * Copyright (c) 2005, 2008 Axis Communications AB
  * Author: Mikael Starvik
  *
  */
 #include <linux/mutex.h>
 #include <linux/interrupt.h>
 #include <linux/poll.h>
-#include <linux/init.h>
-#include <linux/timer.h>
-#include <linux/spinlock.h>
+#include <linux/fs.h>
+#include <linux/cdev.h>
+#include <linux/device.h>
 #include <linux/wait.h>
 
 #include <asm/io.h>
-#include <dma.h>
+#include <mach/dma.h>
 #include <pinmux.h>
 #include <hwregs/reg_rdwr.h>
 #include <hwregs/sser_defs.h>
+#include <hwregs/timer_defs.h>
 #include <hwregs/dma_defs.h>
 #include <hwregs/dma.h>
 #include <hwregs/intr_vect_defs.h>
 /* the rest of the data pointed out by Descr1 and set readp to the start */
 /* of Descr2                                                             */
 
-#define SYNC_SERIAL_MAJOR 125
-
 /* IN_BUFFER_SIZE should be a multiple of 6 to make sure that 24 bit */
 /* words can be handled */
-#define IN_BUFFER_SIZE 12288
-#define IN_DESCR_SIZE 256
-#define NBR_IN_DESCR (IN_BUFFER_SIZE/IN_DESCR_SIZE)
+#define IN_DESCR_SIZE SSP_INPUT_CHUNK_SIZE
+#define NBR_IN_DESCR (8*6)
+#define IN_BUFFER_SIZE (IN_DESCR_SIZE * NBR_IN_DESCR)
 
-#define OUT_BUFFER_SIZE 1024*8
 #define NBR_OUT_DESCR 8
+#define OUT_BUFFER_SIZE (1024 * NBR_OUT_DESCR)
 
 #define DEFAULT_FRAME_RATE 0
 #define DEFAULT_WORD_RATE 7
 
+/* To be removed when we move to pure udev. */
+#define SYNC_SERIAL_MAJOR 125
+
 /* NOTE: Enabling some debug will likely cause overrun or underrun,
- * especially if manual mode is use.
+ * especially if manual mode is used.
  */
 #define DEBUG(x)
 #define DEBUGREAD(x)
 #define DEBUGTRDMA(x)
 #define DEBUGOUTBUF(x)
 
-typedef struct sync_port
-{
-       reg_scope_instances regi_sser;
-       reg_scope_instances regi_dmain;
-       reg_scope_instances regi_dmaout;
+enum syncser_irq_setup {
+       no_irq_setup = 0,
+       dma_irq_setup = 1,
+       manual_irq_setup = 2,
+};
+
+struct sync_port {
+       unsigned long regi_sser;
+       unsigned long regi_dmain;
+       unsigned long regi_dmaout;
+
+       /* Interrupt vectors. */
+       unsigned long dma_in_intr_vect; /* Used for DMA in. */
+       unsigned long dma_out_intr_vect; /* Used for DMA out. */
+       unsigned long syncser_intr_vect; /* Used when no DMA. */
+
+       /* DMA number for in and out. */
+       unsigned int dma_in_nbr;
+       unsigned int dma_out_nbr;
+
+       /* DMA owner. */
+       enum dma_owner req_dma;
 
        char started; /* 1 if port has been started */
        char port_nbr; /* Port 0 or 1 */
@@ -99,22 +117,29 @@ typedef struct sync_port
        char use_dma;  /* 1 if port uses dma */
        char tr_running;
 
-       char init_irqs;
+       enum syncser_irq_setup init_irqs;
        int output;
        int input;
 
        /* Next byte to be read by application */
-       volatile unsigned char *volatile readp;
+       unsigned char *readp;
        /* Next byte to be written by etrax */
-       volatile unsigned char *volatile writep;
+       unsigned char *writep;
 
        unsigned int in_buffer_size;
+       unsigned int in_buffer_len;
        unsigned int inbufchunk;
-       unsigned char out_buffer[OUT_BUFFER_SIZE] __attribute__ ((aligned(32)));
-       unsigned char in_buffer[IN_BUFFER_SIZE]__attribute__ ((aligned(32)));
-       unsigned char flip[IN_BUFFER_SIZE] __attribute__ ((aligned(32)));
-       struct dma_descr_data* next_rx_desc;
-       struct dma_descr_data* prev_rx_desc;
+       /* Data buffers for in and output. */
+       unsigned char out_buffer[OUT_BUFFER_SIZE] __aligned(32);
+       unsigned char in_buffer[IN_BUFFER_SIZE] __aligned(32);
+       unsigned char flip[IN_BUFFER_SIZE] __aligned(32);
+       struct timespec timestamp[NBR_IN_DESCR];
+       struct dma_descr_data *next_rx_desc;
+       struct dma_descr_data *prev_rx_desc;
+
+       struct timeval last_timestamp;
+       int read_ts_idx;
+       int write_ts_idx;
 
        /* Pointer to the first available descriptor in the ring,
         * unless active_tr_descr == catch_tr_descr and a dma
@@ -135,114 +160,138 @@ typedef struct sync_port
        /* Number of bytes currently locked for being read by DMA */
        int out_buf_count;
 
-       dma_descr_data in_descr[NBR_IN_DESCR] __attribute__ ((__aligned__(16)));
-       dma_descr_context in_context __attribute__ ((__aligned__(32)));
-       dma_descr_data out_descr[NBR_OUT_DESCR]
-               __attribute__ ((__aligned__(16)));
-       dma_descr_context out_context __attribute__ ((__aligned__(32)));
+       dma_descr_context in_context __aligned(32);
+       dma_descr_context out_context __aligned(32);
+       dma_descr_data in_descr[NBR_IN_DESCR] __aligned(16);
+       dma_descr_data out_descr[NBR_OUT_DESCR] __aligned(16);
+
        wait_queue_head_t out_wait_q;
        wait_queue_head_t in_wait_q;
 
        spinlock_t lock;
-} sync_port;
+};
 
 static DEFINE_MUTEX(sync_serial_mutex);
 static int etrax_sync_serial_init(void);
 static void initialize_port(int portnbr);
 static inline int sync_data_avail(struct sync_port *port);
 
-static int sync_serial_open(struct inode *, struct file*);
-static int sync_serial_release(struct inode*, struct file*);
+static int sync_serial_open(struct inode *, struct file *);
+static int sync_serial_release(struct inode *, struct file *);
 static unsigned int sync_serial_poll(struct file *filp, poll_table *wait);
 
-static int sync_serial_ioctl(struct file *,
-                            unsigned int cmd, unsigned long arg);
-static ssize_t sync_serial_write(struct file * file, const char * buf,
+static long sync_serial_ioctl(struct file *file,
+                             unsigned int cmd, unsigned long arg);
+static int sync_serial_ioctl_unlocked(struct file *file,
+                                     unsigned int cmd, unsigned long arg);
+static ssize_t sync_serial_write(struct file *file, const char __user *buf,
                                 size_t count, loff_t *ppos);
-static ssize_t sync_serial_read(struct file *file, char *buf,
+static ssize_t sync_serial_read(struct file *file, char __user *buf,
                                size_t count, loff_t *ppos);
 
-#if (defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL_PORT0) && \
-     defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL0_DMA)) || \
-    (defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL_PORT1) && \
-     defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL1_DMA))
+#if ((defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL_PORT0) && \
+       defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL0_DMA)) || \
+       (defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL_PORT1) && \
+       defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL1_DMA)))
 #define SYNC_SER_DMA
+#else
+#define SYNC_SER_MANUAL
 #endif
 
-static void send_word(sync_port* port);
-static void start_dma_out(struct sync_port *port, const char *data, int count);
-static void start_dma_in(sync_port* port);
 #ifdef SYNC_SER_DMA
+static void start_dma_out(struct sync_port *port, const char *data, int count);
+static void start_dma_in(struct sync_port *port);
 static irqreturn_t tr_interrupt(int irq, void *dev_id);
 static irqreturn_t rx_interrupt(int irq, void *dev_id);
 #endif
-
-#if (defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL_PORT0) && \
-     !defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL0_DMA)) || \
-    (defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL_PORT1) && \
-     !defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL1_DMA))
-#define SYNC_SER_MANUAL
-#endif
 #ifdef SYNC_SER_MANUAL
+static void send_word(struct sync_port *port);
 static irqreturn_t manual_interrupt(int irq, void *dev_id);
 #endif
 
-#ifdef CONFIG_ETRAXFS  /* ETRAX FS */
-#define OUT_DMA_NBR 4
-#define IN_DMA_NBR 5
-#define PINMUX_SSER pinmux_sser0
-#define SYNCSER_INST regi_sser0
-#define SYNCSER_INTR_VECT SSER0_INTR_VECT
-#define OUT_DMA_INST regi_dma4
-#define IN_DMA_INST regi_dma5
-#define DMA_OUT_INTR_VECT DMA4_INTR_VECT
-#define DMA_IN_INTR_VECT DMA5_INTR_VECT
-#define REQ_DMA_SYNCSER dma_sser0
-#else                  /* Artpec-3 */
-#define OUT_DMA_NBR 6
-#define IN_DMA_NBR 7
-#define PINMUX_SSER pinmux_sser
-#define SYNCSER_INST regi_sser
-#define SYNCSER_INTR_VECT SSER_INTR_VECT
-#define OUT_DMA_INST regi_dma6
-#define IN_DMA_INST regi_dma7
-#define DMA_OUT_INTR_VECT DMA6_INTR_VECT
-#define DMA_IN_INTR_VECT DMA7_INTR_VECT
-#define REQ_DMA_SYNCSER dma_sser
+#define artpec_pinmux_alloc_fixed crisv32_pinmux_alloc_fixed
+#define artpec_request_dma crisv32_request_dma
+#define artpec_free_dma crisv32_free_dma
+
+#ifdef CONFIG_ETRAXFS
+/* ETRAX FS */
+#define DMA_OUT_NBR0           SYNC_SER0_TX_DMA_NBR
+#define DMA_IN_NBR0            SYNC_SER0_RX_DMA_NBR
+#define DMA_OUT_NBR1           SYNC_SER1_TX_DMA_NBR
+#define DMA_IN_NBR1            SYNC_SER1_RX_DMA_NBR
+#define PINMUX_SSER0           pinmux_sser0
+#define PINMUX_SSER1           pinmux_sser1
+#define SYNCSER_INST0          regi_sser0
+#define SYNCSER_INST1          regi_sser1
+#define SYNCSER_INTR_VECT0     SSER0_INTR_VECT
+#define SYNCSER_INTR_VECT1     SSER1_INTR_VECT
+#define OUT_DMA_INST0          regi_dma4
+#define IN_DMA_INST0           regi_dma5
+#define DMA_OUT_INTR_VECT0     DMA4_INTR_VECT
+#define DMA_OUT_INTR_VECT1     DMA7_INTR_VECT
+#define DMA_IN_INTR_VECT0      DMA5_INTR_VECT
+#define DMA_IN_INTR_VECT1      DMA6_INTR_VECT
+#define REQ_DMA_SYNCSER0       dma_sser0
+#define REQ_DMA_SYNCSER1       dma_sser1
+#if defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL1_DMA)
+#define PORT1_DMA 1
+#else
+#define PORT1_DMA 0
+#endif
+#elif defined(CONFIG_CRIS_MACH_ARTPEC3)
+/* ARTPEC-3 */
+#define DMA_OUT_NBR0           SYNC_SER_TX_DMA_NBR
+#define DMA_IN_NBR0            SYNC_SER_RX_DMA_NBR
+#define PINMUX_SSER0           pinmux_sser
+#define SYNCSER_INST0          regi_sser
+#define SYNCSER_INTR_VECT0     SSER_INTR_VECT
+#define OUT_DMA_INST0          regi_dma6
+#define IN_DMA_INST0           regi_dma7
+#define DMA_OUT_INTR_VECT0     DMA6_INTR_VECT
+#define DMA_IN_INTR_VECT0      DMA7_INTR_VECT
+#define REQ_DMA_SYNCSER0       dma_sser
+#define REQ_DMA_SYNCSER1       dma_sser
 #endif
 
-/* The ports */
-static struct sync_port ports[]=
-{
-       {
-               .regi_sser             = SYNCSER_INST,
-               .regi_dmaout           = OUT_DMA_INST,
-               .regi_dmain            = IN_DMA_INST,
 #if defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL0_DMA)
-                .use_dma               = 1,
+#define PORT0_DMA 1
 #else
-                .use_dma               = 0,
+#define PORT0_DMA 0
 #endif
-       }
-#ifdef CONFIG_ETRAXFS
-       ,
 
+/* The ports */
+static struct sync_port ports[] = {
        {
-               .regi_sser             = regi_sser1,
-               .regi_dmaout           = regi_dma6,
-               .regi_dmain            = regi_dma7,
-#if defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL1_DMA)
-                .use_dma               = 1,
-#else
-                .use_dma               = 0,
-#endif
-       }
+               .regi_sser              = SYNCSER_INST0,
+               .regi_dmaout            = OUT_DMA_INST0,
+               .regi_dmain             = IN_DMA_INST0,
+               .use_dma                = PORT0_DMA,
+               .dma_in_intr_vect       = DMA_IN_INTR_VECT0,
+               .dma_out_intr_vect      = DMA_OUT_INTR_VECT0,
+               .dma_in_nbr             = DMA_IN_NBR0,
+               .dma_out_nbr            = DMA_OUT_NBR0,
+               .req_dma                = REQ_DMA_SYNCSER0,
+               .syncser_intr_vect      = SYNCSER_INTR_VECT0,
+       },
+#ifdef CONFIG_ETRAXFS
+       {
+               .regi_sser              = SYNCSER_INST1,
+               .regi_dmaout            = regi_dma6,
+               .regi_dmain             = regi_dma7,
+               .use_dma                = PORT1_DMA,
+               .dma_in_intr_vect       = DMA_IN_INTR_VECT1,
+               .dma_out_intr_vect      = DMA_OUT_INTR_VECT1,
+               .dma_in_nbr             = DMA_IN_NBR1,
+               .dma_out_nbr            = DMA_OUT_NBR1,
+               .req_dma                = REQ_DMA_SYNCSER1,
+               .syncser_intr_vect      = SYNCSER_INTR_VECT1,
+       },
 #endif
 };
 
 #define NBR_PORTS ARRAY_SIZE(ports)
 
-static const struct file_operations sync_serial_fops = {
+static const struct file_operations syncser_fops = {
        .owner          = THIS_MODULE,
        .write          = sync_serial_write,
        .read           = sync_serial_read,
@@ -253,61 +302,40 @@ static const struct file_operations sync_serial_fops = {
        .llseek         = noop_llseek,
 };
 
-static int __init etrax_sync_serial_init(void)
-{
-       ports[0].enabled = 0;
-#ifdef CONFIG_ETRAXFS
-       ports[1].enabled = 0;
-#endif
-       if (register_chrdev(SYNC_SERIAL_MAJOR, "sync serial",
-                       &sync_serial_fops) < 0) {
-               printk(KERN_WARNING
-                       "Unable to get major for synchronous serial port\n");
-               return -EBUSY;
-       }
-
-       /* Initialize Ports */
-#if defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL_PORT0)
-       if (crisv32_pinmux_alloc_fixed(PINMUX_SSER)) {
-               printk(KERN_WARNING
-                       "Unable to alloc pins for synchronous serial port 0\n");
-               return -EIO;
-       }
-       ports[0].enabled = 1;
-       initialize_port(0);
-#endif
-
-#if defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL_PORT1)
-       if (crisv32_pinmux_alloc_fixed(pinmux_sser1)) {
-               printk(KERN_WARNING
-                       "Unable to alloc pins for synchronous serial port 0\n");
-               return -EIO;
-       }
-       ports[1].enabled = 1;
-       initialize_port(1);
-#endif
+static dev_t syncser_first;
+static int minor_count = NBR_PORTS;
+#define SYNCSER_NAME "syncser"
+static struct cdev *syncser_cdev;
+static struct class *syncser_class;
 
-#ifdef CONFIG_ETRAXFS
-       printk(KERN_INFO "ETRAX FS synchronous serial port driver\n");
-#else
-       printk(KERN_INFO "Artpec-3 synchronous serial port driver\n");
-#endif
-       return 0;
+static void sync_serial_start_port(struct sync_port *port)
+{
+       reg_sser_rw_cfg cfg = REG_RD(sser, port->regi_sser, rw_cfg);
+       reg_sser_rw_tr_cfg tr_cfg =
+               REG_RD(sser, port->regi_sser, rw_tr_cfg);
+       reg_sser_rw_rec_cfg rec_cfg =
+               REG_RD(sser, port->regi_sser, rw_rec_cfg);
+       cfg.en = regk_sser_yes;
+       tr_cfg.tr_en = regk_sser_yes;
+       rec_cfg.rec_en = regk_sser_yes;
+       REG_WR(sser, port->regi_sser, rw_cfg, cfg);
+       REG_WR(sser, port->regi_sser, rw_tr_cfg, tr_cfg);
+       REG_WR(sser, port->regi_sser, rw_rec_cfg, rec_cfg);
+       port->started = 1;
 }
 
 static void __init initialize_port(int portnbr)
 {
-       int __attribute__((unused)) i;
        struct sync_port *port = &ports[portnbr];
-       reg_sser_rw_cfg cfg = {0};
-       reg_sser_rw_frm_cfg frm_cfg = {0};
-       reg_sser_rw_tr_cfg tr_cfg = {0};
-       reg_sser_rw_rec_cfg rec_cfg = {0};
+       reg_sser_rw_cfg cfg = { 0 };
+       reg_sser_rw_frm_cfg frm_cfg = { 0 };
+       reg_sser_rw_tr_cfg tr_cfg = { 0 };
+       reg_sser_rw_rec_cfg rec_cfg = { 0 };
 
-       DEBUG(printk(KERN_DEBUG "Init sync serial port %d\n", portnbr));
+       DEBUG(pr_info("Init sync serial port %d\n", portnbr));
 
        port->port_nbr = portnbr;
-       port->init_irqs = 1;
+       port->init_irqs = no_irq_setup;
 
        port->out_rd_ptr = port->out_buffer;
        port->out_buf_count = 0;
@@ -318,10 +346,11 @@ static void __init initialize_port(int portnbr)
        port->readp = port->flip;
        port->writep = port->flip;
        port->in_buffer_size = IN_BUFFER_SIZE;
+       port->in_buffer_len = 0;
        port->inbufchunk = IN_DESCR_SIZE;
-       port->next_rx_desc = &port->in_descr[0];
-       port->prev_rx_desc = &port->in_descr[NBR_IN_DESCR-1];
-       port->prev_rx_desc->eol = 1;
+
+       port->read_ts_idx = 0;
+       port->write_ts_idx = 0;
 
        init_waitqueue_head(&port->out_wait_q);
        init_waitqueue_head(&port->in_wait_q);
@@ -368,14 +397,18 @@ static void __init initialize_port(int portnbr)
        REG_WR(sser, port->regi_sser, rw_rec_cfg, rec_cfg);
 
 #ifdef SYNC_SER_DMA
-       /* Setup the descriptor ring for dma out/transmit. */
-       for (i = 0; i < NBR_OUT_DESCR; i++) {
-               port->out_descr[i].wait = 0;
-               port->out_descr[i].intr = 1;
-               port->out_descr[i].eol = 0;
-               port->out_descr[i].out_eop = 0;
-               port->out_descr[i].next =
-                       (dma_descr_data *)virt_to_phys(&port->out_descr[i+1]);
+       {
+               int i;
+               /* Setup the descriptor ring for dma out/transmit. */
+               for (i = 0; i < NBR_OUT_DESCR; i++) {
+                       dma_descr_data *descr = &port->out_descr[i];
+                       descr->wait = 0;
+                       descr->intr = 1;
+                       descr->eol = 0;
+                       descr->out_eop = 0;
+                       descr->next =
+                               (dma_descr_data *)virt_to_phys(&descr[i+1]);
+               }
        }
 
        /* Create a ring from the list. */
@@ -391,201 +424,116 @@ static void __init initialize_port(int portnbr)
 
 static inline int sync_data_avail(struct sync_port *port)
 {
-       int avail;
-       unsigned char *start;
-       unsigned char *end;
-
-       start = (unsigned char*)port->readp; /* cast away volatile */
-       end = (unsigned char*)port->writep;  /* cast away volatile */
-       /* 0123456789  0123456789
-        *  -----      -    -----
-        *  ^rp  ^wp    ^wp ^rp
-        */
-
-       if (end >= start)
-               avail = end - start;
-       else
-               avail = port->in_buffer_size - (start - end);
-       return avail;
-}
-
-static inline int sync_data_avail_to_end(struct sync_port *port)
-{
-       int avail;
-       unsigned char *start;
-       unsigned char *end;
-
-       start = (unsigned char*)port->readp; /* cast away volatile */
-       end = (unsigned char*)port->writep;  /* cast away volatile */
-       /* 0123456789  0123456789
-        *  -----           -----
-        *  ^rp  ^wp    ^wp ^rp
-        */
-
-       if (end >= start)
-               avail = end - start;
-       else
-               avail = port->flip + port->in_buffer_size - start;
-       return avail;
+       return port->in_buffer_len;
 }
 
 static int sync_serial_open(struct inode *inode, struct file *file)
 {
+       int ret = 0;
        int dev = iminor(inode);
-       int ret = -EBUSY;
-       sync_port *port;
-       reg_dma_rw_cfg cfg = {.en = regk_dma_yes};
-       reg_dma_rw_intr_mask intr_mask = {.data = regk_dma_yes};
+       struct sync_port *port;
+#ifdef SYNC_SER_DMA
+       reg_dma_rw_cfg cfg = { .en = regk_dma_yes };
+       reg_dma_rw_intr_mask intr_mask = { .data = regk_dma_yes };
+#endif
 
-       mutex_lock(&sync_serial_mutex);
-       DEBUG(printk(KERN_DEBUG "Open sync serial port %d\n", dev));
+       DEBUG(pr_debug("Open sync serial port %d\n", dev));
 
-       if (dev < 0 || dev >= NBR_PORTS || !ports[dev].enabled)
-       {
-               DEBUG(printk(KERN_DEBUG "Invalid minor %d\n", dev));
-               ret = -ENODEV;
-               goto out;
+       if (dev < 0 || dev >= NBR_PORTS || !ports[dev].enabled) {
+               DEBUG(pr_info("Invalid minor %d\n", dev));
+               return -ENODEV;
        }
        port = &ports[dev];
        /* Allow open this device twice (assuming one reader and one writer) */
-       if (port->busy == 2)
-       {
-               DEBUG(printk(KERN_DEBUG "Device is busy.. \n"));
-               goto out;
+       if (port->busy == 2) {
+               DEBUG(pr_info("syncser%d is busy\n", dev));
+               return -EBUSY;
        }
 
+       mutex_lock(&sync_serial_mutex);
 
-       if (port->init_irqs) {
-               if (port->use_dma) {
-                       if (port == &ports[0]) {
-#ifdef SYNC_SER_DMA
-                               if (request_irq(DMA_OUT_INTR_VECT,
-                                               tr_interrupt,
-                                               0,
-                                               "synchronous serial 0 dma tr",
-                                               &ports[0])) {
-                                       printk(KERN_CRIT "Can't allocate sync serial port 0 IRQ");
-                                       goto out;
-                               } else if (request_irq(DMA_IN_INTR_VECT,
-                                               rx_interrupt,
-                                               0,
-                                               "synchronous serial 1 dma rx",
-                                               &ports[0])) {
-                                       free_irq(DMA_OUT_INTR_VECT, &port[0]);
-                                       printk(KERN_CRIT "Can't allocate sync serial port 0 IRQ");
-                                       goto out;
-                               } else if (crisv32_request_dma(OUT_DMA_NBR,
-                                               "synchronous serial 0 dma tr",
-                                               DMA_VERBOSE_ON_ERROR,
-                                               0,
-                                               REQ_DMA_SYNCSER)) {
-                                       free_irq(DMA_OUT_INTR_VECT, &port[0]);
-                                       free_irq(DMA_IN_INTR_VECT, &port[0]);
-                                       printk(KERN_CRIT "Can't allocate sync serial port 0 TX DMA channel");
-                                       goto out;
-                               } else if (crisv32_request_dma(IN_DMA_NBR,
-                                               "synchronous serial 0 dma rec",
-                                               DMA_VERBOSE_ON_ERROR,
-                                               0,
-                                               REQ_DMA_SYNCSER)) {
-                                       crisv32_free_dma(OUT_DMA_NBR);
-                                       free_irq(DMA_OUT_INTR_VECT, &port[0]);
-                                       free_irq(DMA_IN_INTR_VECT, &port[0]);
-                                       printk(KERN_CRIT "Can't allocate sync serial port 1 RX DMA channel");
-                                       goto out;
-                               }
-#endif
-                       }
-#ifdef CONFIG_ETRAXFS
-                       else if (port == &ports[1]) {
+       /* Clear any stale date left in the flip buffer */
+       port->readp = port->writep = port->flip;
+       port->in_buffer_len = 0;
+       port->read_ts_idx = 0;
+       port->write_ts_idx = 0;
+
+       if (port->init_irqs != no_irq_setup) {
+               /* Init only on first call. */
+               port->busy++;
+               mutex_unlock(&sync_serial_mutex);
+               return 0;
+       }
+       if (port->use_dma) {
 #ifdef SYNC_SER_DMA
-                               if (request_irq(DMA6_INTR_VECT,
-                                               tr_interrupt,
-                                               0,
-                                               "synchronous serial 1 dma tr",
-                                               &ports[1])) {
-                                       printk(KERN_CRIT "Can't allocate sync serial port 1 IRQ");
-                                       goto out;
-                               } else if (request_irq(DMA7_INTR_VECT,
-                                                      rx_interrupt,
-                                                      0,
-                                                      "synchronous serial 1 dma rx",
-                                                      &ports[1])) {
-                                       free_irq(DMA6_INTR_VECT, &ports[1]);
-                                       printk(KERN_CRIT "Can't allocate sync serial port 3 IRQ");
-                                       goto out;
-                               } else if (crisv32_request_dma(
-                                               SYNC_SER1_TX_DMA_NBR,
-                                               "synchronous serial 1 dma tr",
-                                               DMA_VERBOSE_ON_ERROR,
-                                               0,
-                                               dma_sser1)) {
-                                       free_irq(DMA6_INTR_VECT, &ports[1]);
-                                       free_irq(DMA7_INTR_VECT, &ports[1]);
-                                       printk(KERN_CRIT "Can't allocate sync serial port 3 TX DMA channel");
-                                       goto out;
-                               } else if (crisv32_request_dma(
-                                               SYNC_SER1_RX_DMA_NBR,
-                                               "synchronous serial 3 dma rec",
-                                               DMA_VERBOSE_ON_ERROR,
-                                               0,
-                                               dma_sser1)) {
-                                       crisv32_free_dma(SYNC_SER1_TX_DMA_NBR);
-                                       free_irq(DMA6_INTR_VECT, &ports[1]);
-                                       free_irq(DMA7_INTR_VECT, &ports[1]);
-                                       printk(KERN_CRIT "Can't allocate sync serial port 3 RX DMA channel");
-                                       goto out;
-                               }
-#endif
-                       }
+               const char *tmp;
+               DEBUG(pr_info("Using DMA for syncser%d\n", dev));
+
+               tmp = dev == 0 ? "syncser0 tx" : "syncser1 tx";
+               if (request_irq(port->dma_out_intr_vect, tr_interrupt, 0,
+                               tmp, port)) {
+                       pr_err("Can't alloc syncser%d TX IRQ", dev);
+                       ret = -EBUSY;
+                       goto unlock_and_exit;
+               }
+               if (artpec_request_dma(port->dma_out_nbr, tmp,
+                               DMA_VERBOSE_ON_ERROR, 0, port->req_dma)) {
+                       free_irq(port->dma_out_intr_vect, port);
+                       pr_err("Can't alloc syncser%d TX DMA", dev);
+                       ret = -EBUSY;
+                       goto unlock_and_exit;
+               }
+               tmp = dev == 0 ? "syncser0 rx" : "syncser1 rx";
+               if (request_irq(port->dma_in_intr_vect, rx_interrupt, 0,
+                               tmp, port)) {
+                       artpec_free_dma(port->dma_out_nbr);
+                       free_irq(port->dma_out_intr_vect, port);
+                       pr_err("Can't alloc syncser%d RX IRQ", dev);
+                       ret = -EBUSY;
+                       goto unlock_and_exit;
+               }
+               if (artpec_request_dma(port->dma_in_nbr, tmp,
+                               DMA_VERBOSE_ON_ERROR, 0, port->req_dma)) {
+                       artpec_free_dma(port->dma_out_nbr);
+                       free_irq(port->dma_out_intr_vect, port);
+                       free_irq(port->dma_in_intr_vect, port);
+                       pr_err("Can't alloc syncser%d RX DMA", dev);
+                       ret = -EBUSY;
+                       goto unlock_and_exit;
+               }
+               /* Enable DMAs */
+               REG_WR(dma, port->regi_dmain, rw_cfg, cfg);
+               REG_WR(dma, port->regi_dmaout, rw_cfg, cfg);
+               /* Enable DMA IRQs */
+               REG_WR(dma, port->regi_dmain, rw_intr_mask, intr_mask);
+               REG_WR(dma, port->regi_dmaout, rw_intr_mask, intr_mask);
+               /* Set up wordsize = 1 for DMAs. */
+               DMA_WR_CMD(port->regi_dmain, regk_dma_set_w_size1);
+               DMA_WR_CMD(port->regi_dmaout, regk_dma_set_w_size1);
+
+               start_dma_in(port);
+               port->init_irqs = dma_irq_setup;
 #endif
-                        /* Enable DMAs */
-                       REG_WR(dma, port->regi_dmain, rw_cfg, cfg);
-                       REG_WR(dma, port->regi_dmaout, rw_cfg, cfg);
-                       /* Enable DMA IRQs */
-                       REG_WR(dma, port->regi_dmain, rw_intr_mask, intr_mask);
-                       REG_WR(dma, port->regi_dmaout, rw_intr_mask, intr_mask);
-                       /* Set up wordsize = 1 for DMAs. */
-                       DMA_WR_CMD (port->regi_dmain, regk_dma_set_w_size1);
-                       DMA_WR_CMD (port->regi_dmaout, regk_dma_set_w_size1);
-
-                       start_dma_in(port);
-                       port->init_irqs = 0;
-               } else { /* !port->use_dma */
+       } else { /* !port->use_dma */
 #ifdef SYNC_SER_MANUAL
-                       if (port == &ports[0]) {
-                               if (request_irq(SYNCSER_INTR_VECT,
-                                               manual_interrupt,
-                                               0,
-                                               "synchronous serial manual irq",
-                                               &ports[0])) {
-                                       printk("Can't allocate sync serial manual irq");
-                                       goto out;
-                               }
-                       }
-#ifdef CONFIG_ETRAXFS
-                       else if (port == &ports[1]) {
-                               if (request_irq(SSER1_INTR_VECT,
-                                               manual_interrupt,
-                                               0,
-                                               "synchronous serial manual irq",
-                                               &ports[1])) {
-                                       printk(KERN_CRIT "Can't allocate sync serial manual irq");
-                                       goto out;
-                               }
-                       }
-#endif
-                       port->init_irqs = 0;
+               const char *tmp = dev == 0 ? "syncser0 manual irq" :
+                                            "syncser1 manual irq";
+               if (request_irq(port->syncser_intr_vect, manual_interrupt,
+                               0, tmp, port)) {
+                       pr_err("Can't alloc syncser%d manual irq",
+                               dev);
+                       ret = -EBUSY;
+                       goto unlock_and_exit;
+               }
+               port->init_irqs = manual_irq_setup;
 #else
-                       panic("sync_serial: Manual mode not supported.\n");
+               panic("sync_serial: Manual mode not supported\n");
 #endif /* SYNC_SER_MANUAL */
-               }
-
-       } /* port->init_irqs */
-
+       }
        port->busy++;
        ret = 0;
-out:
+
+unlock_and_exit:
        mutex_unlock(&sync_serial_mutex);
        return ret;
 }
@@ -593,18 +541,17 @@ out:
 static int sync_serial_release(struct inode *inode, struct file *file)
 {
        int dev = iminor(inode);
-       sync_port *port;
+       struct sync_port *port;
 
-       if (dev < 0 || dev >= NBR_PORTS || !ports[dev].enabled)
-       {
-               DEBUG(printk("Invalid minor %d\n", dev));
+       if (dev < 0 || dev >= NBR_PORTS || !ports[dev].enabled) {
+               DEBUG(pr_info("Invalid minor %d\n", dev));
                return -ENODEV;
        }
        port = &ports[dev];
        if (port->busy)
                port->busy--;
        if (!port->busy)
-          /* XXX */ ;
+               /* XXX */;
        return 0;
 }
 
@@ -612,21 +559,15 @@ static unsigned int sync_serial_poll(struct file *file, poll_table *wait)
 {
        int dev = iminor(file_inode(file));
        unsigned int mask = 0;
-       sync_port *port;
-       DEBUGPOLL( static unsigned int prev_mask = 0; );
+       struct sync_port *port;
+       DEBUGPOLL(
+       static unsigned int prev_mask;
+       );
 
        port = &ports[dev];
 
-       if (!port->started) {
-               reg_sser_rw_cfg cfg = REG_RD(sser, port->regi_sser, rw_cfg);
-               reg_sser_rw_rec_cfg rec_cfg =
-                       REG_RD(sser, port->regi_sser, rw_rec_cfg);
-               cfg.en = regk_sser_yes;
-               rec_cfg.rec_en = port->input;
-               REG_WR(sser, port->regi_sser, rw_cfg, cfg);
-               REG_WR(sser, port->regi_sser, rw_rec_cfg, rec_cfg);
-               port->started = 1;
-       }
+       if (!port->started)
+               sync_serial_start_port(port);
 
        poll_wait(file, &port->out_wait_q, wait);
        poll_wait(file, &port->in_wait_q, wait);
@@ -645,33 +586,175 @@ static unsigned int sync_serial_poll(struct file *file, poll_table *wait)
        if (port->input && sync_data_avail(port) >= port->inbufchunk)
                mask |= POLLIN | POLLRDNORM;
 
-       DEBUGPOLL(if (mask != prev_mask)
-             printk("sync_serial_poll: mask 0x%08X %s %s\n", mask,
-                    mask&POLLOUT?"POLLOUT":"", mask&POLLIN?"POLLIN":"");
-             prev_mask = mask;
-             );
+       DEBUGPOLL(
+       if (mask != prev_mask)
+               pr_info("sync_serial_poll: mask 0x%08X %s %s\n",
+                       mask,
+                       mask & POLLOUT ? "POLLOUT" : "",
+                       mask & POLLIN ? "POLLIN" : "");
+               prev_mask = mask;
+       );
        return mask;
 }
 
-static int sync_serial_ioctl(struct file *file,
-                 unsigned int cmd, unsigned long arg)
+static ssize_t __sync_serial_read(struct file *file,
+                                 char __user *buf,
+                                 size_t count,
+                                 loff_t *ppos,
+                                 struct timespec *ts)
+{
+       unsigned long flags;
+       int dev = MINOR(file->f_dentry->d_inode->i_rdev);
+       int avail;
+       struct sync_port *port;
+       unsigned char *start;
+       unsigned char *end;
+
+       if (dev < 0 || dev >= NBR_PORTS || !ports[dev].enabled) {
+               DEBUG(pr_info("Invalid minor %d\n", dev));
+               return -ENODEV;
+       }
+       port = &ports[dev];
+
+       if (!port->started)
+               sync_serial_start_port(port);
+
+       /* Calculate number of available bytes */
+       /* Save pointers to avoid that they are modified by interrupt */
+       spin_lock_irqsave(&port->lock, flags);
+       start = port->readp;
+       end = port->writep;
+       spin_unlock_irqrestore(&port->lock, flags);
+
+       while ((start == end) && !port->in_buffer_len) {
+               if (file->f_flags & O_NONBLOCK)
+                       return -EAGAIN;
+
+               wait_event_interruptible(port->in_wait_q,
+                                        !(start == end && !port->full));
+
+               if (signal_pending(current))
+                       return -EINTR;
+
+               spin_lock_irqsave(&port->lock, flags);
+               start = port->readp;
+               end = port->writep;
+               spin_unlock_irqrestore(&port->lock, flags);
+       }
+
+       DEBUGREAD(pr_info("R%d c %d ri %u wi %u /%u\n",
+                         dev, count,
+                         start - port->flip, end - port->flip,
+                         port->in_buffer_size));
+
+       /* Lazy read, never return wrapped data. */
+       if (end > start)
+               avail = end - start;
+       else
+               avail = port->flip + port->in_buffer_size - start;
+
+       count = count > avail ? avail : count;
+       if (copy_to_user(buf, start, count))
+               return -EFAULT;
+
+       /* If timestamp requested, find timestamp of first returned byte
+        * and copy it.
+        * N.B: Applications that request timstamps MUST read data in
+        * chunks that are multiples of IN_DESCR_SIZE.
+        * Otherwise the timestamps will not be aligned to the data read.
+        */
+       if (ts != NULL) {
+               int idx = port->read_ts_idx;
+               memcpy(ts, &port->timestamp[idx], sizeof(struct timespec));
+               port->read_ts_idx += count / IN_DESCR_SIZE;
+               if (port->read_ts_idx >= NBR_IN_DESCR)
+                       port->read_ts_idx = 0;
+       }
+
+       spin_lock_irqsave(&port->lock, flags);
+       port->readp += count;
+       /* Check for wrap */
+       if (port->readp >= port->flip + port->in_buffer_size)
+               port->readp = port->flip;
+       port->in_buffer_len -= count;
+       port->full = 0;
+       spin_unlock_irqrestore(&port->lock, flags);
+
+       DEBUGREAD(pr_info("r %d\n", count));
+
+       return count;
+}
+
+static ssize_t sync_serial_input(struct file *file, unsigned long arg)
+{
+       struct ssp_request req;
+       int count;
+       int ret;
+
+       /* Copy the request structure from user-mode. */
+       ret = copy_from_user(&req, (struct ssp_request __user *)arg,
+               sizeof(struct ssp_request));
+
+       if (ret) {
+               DEBUG(pr_info("sync_serial_input copy from user failed\n"));
+               return -EFAULT;
+       }
+
+       /* To get the timestamps aligned, make sure that 'len'
+        * is a multiple of IN_DESCR_SIZE.
+        */
+       if ((req.len % IN_DESCR_SIZE) != 0) {
+               DEBUG(pr_info("sync_serial: req.len %x, IN_DESCR_SIZE %x\n",
+                             req.len, IN_DESCR_SIZE));
+               return -EFAULT;
+       }
+
+       /* Do the actual read. */
+       /* Note that req.buf is actually a pointer to user space. */
+       count = __sync_serial_read(file, req.buf, req.len,
+                                  NULL, &req.ts);
+
+       if (count < 0) {
+               DEBUG(pr_info("sync_serial_input read failed\n"));
+               return count;
+       }
+
+       /* Copy the request back to user-mode. */
+       ret = copy_to_user((struct ssp_request __user *)arg, &req,
+               sizeof(struct ssp_request));
+
+       if (ret) {
+               DEBUG(pr_info("syncser input copy2user failed\n"));
+               return -EFAULT;
+       }
+
+       /* Return the number of bytes read. */
+       return count;
+}
+
+
+static int sync_serial_ioctl_unlocked(struct file *file,
+                                     unsigned int cmd, unsigned long arg)
 {
        int return_val = 0;
        int dma_w_size = regk_dma_set_w_size1;
        int dev = iminor(file_inode(file));
-       sync_port *port;
+       struct sync_port *port;
        reg_sser_rw_tr_cfg tr_cfg;
        reg_sser_rw_rec_cfg rec_cfg;
        reg_sser_rw_frm_cfg frm_cfg;
        reg_sser_rw_cfg gen_cfg;
        reg_sser_rw_intr_mask intr_mask;
 
-       if (dev < 0 || dev >= NBR_PORTS || !ports[dev].enabled)
-       {
-               DEBUG(printk("Invalid minor %d\n", dev));
+       if (dev < 0 || dev >= NBR_PORTS || !ports[dev].enabled) {
+               DEBUG(pr_info("Invalid minor %d\n", dev));
                return -1;
        }
-        port = &ports[dev];
+
+       if (cmd == SSP_INPUT)
+               return sync_serial_input(file, arg);
+
+       port = &ports[dev];
        spin_lock_irq(&port->lock);
 
        tr_cfg = REG_RD(sser, port->regi_sser, rw_tr_cfg);
@@ -680,11 +763,9 @@ static int sync_serial_ioctl(struct file *file,
        gen_cfg = REG_RD(sser, port->regi_sser, rw_cfg);
        intr_mask = REG_RD(sser, port->regi_sser, rw_intr_mask);
 
-       switch(cmd)
-       {
+       switch (cmd) {
        case SSP_SPEED:
-               if (GET_SPEED(arg) == CODEC)
-               {
+               if (GET_SPEED(arg) == CODEC) {
                        unsigned int freq;
 
                        gen_cfg.base_freq = regk_sser_f32;
@@ -701,15 +782,25 @@ static int sync_serial_ioctl(struct file *file,
                        case FREQ_256kHz:
                                gen_cfg.clk_div = 125 *
                                        (1 << (freq - FREQ_256kHz)) - 1;
-                       break;
+                               break;
                        case FREQ_512kHz:
                                gen_cfg.clk_div = 62;
-                       break;
+                               break;
                        case FREQ_1MHz:
                        case FREQ_2MHz:
                        case FREQ_4MHz:
                                gen_cfg.clk_div = 8 * (1 << freq) - 1;
-                       break;
+                               break;
+                       }
+               } else if (GET_SPEED(arg) == CODEC_f32768) {
+                       gen_cfg.base_freq = regk_sser_f32_768;
+                       switch (GET_FREQ(arg)) {
+                       case FREQ_4096kHz:
+                               gen_cfg.clk_div = 7;
+                               break;
+                       default:
+                               spin_unlock_irq(&port->lock);
+                               return -EINVAL;
                        }
                } else {
                        gen_cfg.base_freq = regk_sser_f29_493;
@@ -767,62 +858,64 @@ static int sync_serial_ioctl(struct file *file,
 
                break;
        case SSP_MODE:
-               switch(arg)
-               {
-                       case MASTER_OUTPUT:
-                               port->output = 1;
-                               port->input = 0;
-                               frm_cfg.out_on = regk_sser_tr;
-                               frm_cfg.frame_pin_dir = regk_sser_out;
-                               gen_cfg.clk_dir = regk_sser_out;
-                               break;
-                       case SLAVE_OUTPUT:
-                               port->output = 1;
-                               port->input = 0;
-                               frm_cfg.frame_pin_dir = regk_sser_in;
-                               gen_cfg.clk_dir = regk_sser_in;
-                               break;
-                       case MASTER_INPUT:
-                               port->output = 0;
-                               port->input = 1;
-                               frm_cfg.frame_pin_dir = regk_sser_out;
-                               frm_cfg.out_on = regk_sser_intern_tb;
-                               gen_cfg.clk_dir = regk_sser_out;
-                               break;
-                       case SLAVE_INPUT:
-                               port->output = 0;
-                               port->input = 1;
-                               frm_cfg.frame_pin_dir = regk_sser_in;
-                               gen_cfg.clk_dir = regk_sser_in;
-                               break;
-                       case MASTER_BIDIR:
-                               port->output = 1;
-                               port->input = 1;
-                               frm_cfg.frame_pin_dir = regk_sser_out;
-                               frm_cfg.out_on = regk_sser_intern_tb;
-                               gen_cfg.clk_dir = regk_sser_out;
-                               break;
-                       case SLAVE_BIDIR:
-                               port->output = 1;
-                               port->input = 1;
-                               frm_cfg.frame_pin_dir = regk_sser_in;
-                               gen_cfg.clk_dir = regk_sser_in;
-                               break;
-                       default:
-                               spin_unlock_irq(&port->lock);
-                               return -EINVAL;
+               switch (arg) {
+               case MASTER_OUTPUT:
+                       port->output = 1;
+                       port->input = 0;
+                       frm_cfg.out_on = regk_sser_tr;
+                       frm_cfg.frame_pin_dir = regk_sser_out;
+                       gen_cfg.clk_dir = regk_sser_out;
+                       break;
+               case SLAVE_OUTPUT:
+                       port->output = 1;
+                       port->input = 0;
+                       frm_cfg.frame_pin_dir = regk_sser_in;
+                       gen_cfg.clk_dir = regk_sser_in;
+                       break;
+               case MASTER_INPUT:
+                       port->output = 0;
+                       port->input = 1;
+                       frm_cfg.frame_pin_dir = regk_sser_out;
+                       frm_cfg.out_on = regk_sser_intern_tb;
+                       gen_cfg.clk_dir = regk_sser_out;
+                       break;
+               case SLAVE_INPUT:
+                       port->output = 0;
+                       port->input = 1;
+                       frm_cfg.frame_pin_dir = regk_sser_in;
+                       gen_cfg.clk_dir = regk_sser_in;
+                       break;
+               case MASTER_BIDIR:
+                       port->output = 1;
+                       port->input = 1;
+                       frm_cfg.frame_pin_dir = regk_sser_out;
+                       frm_cfg.out_on = regk_sser_intern_tb;
+                       gen_cfg.clk_dir = regk_sser_out;
+                       break;
+               case SLAVE_BIDIR:
+                       port->output = 1;
+                       port->input = 1;
+                       frm_cfg.frame_pin_dir = regk_sser_in;
+                       gen_cfg.clk_dir = regk_sser_in;
+                       break;
+               default:
+                       spin_unlock_irq(&port->lock);
+                       return -EINVAL;
                }
-               if (!port->use_dma || (arg == MASTER_OUTPUT || arg == SLAVE_OUTPUT))
+               if (!port->use_dma || arg == MASTER_OUTPUT ||
+                               arg == SLAVE_OUTPUT)
                        intr_mask.rdav = regk_sser_yes;
                break;
        case SSP_FRAME_SYNC:
                if (arg & NORMAL_SYNC) {
                        frm_cfg.rec_delay = 1;
                        frm_cfg.tr_delay = 1;
-               }
-               else if (arg & EARLY_SYNC)
+               } else if (arg & EARLY_SYNC)
                        frm_cfg.rec_delay = frm_cfg.tr_delay = 0;
-               else if (arg & SECOND_WORD_SYNC) {
+               else if (arg & LATE_SYNC) {
+                       frm_cfg.tr_delay = 2;
+                       frm_cfg.rec_delay = 2;
+               } else if (arg & SECOND_WORD_SYNC) {
                        frm_cfg.rec_delay = 7;
                        frm_cfg.tr_delay = 1;
                }
@@ -914,15 +1007,12 @@ static int sync_serial_ioctl(struct file *file,
                frm_cfg.type = regk_sser_level;
                frm_cfg.tr_delay = 1;
                frm_cfg.level = regk_sser_neg_lo;
-               if (arg & SPI_SLAVE)
-               {
+               if (arg & SPI_SLAVE) {
                        rec_cfg.clk_pol = regk_sser_neg;
                        gen_cfg.clk_dir = regk_sser_in;
                        port->input = 1;
                        port->output = 0;
-               }
-               else
-               {
+               } else {
                        gen_cfg.out_clk_pol = regk_sser_pos;
                        port->input = 0;
                        port->output = 1;
@@ -965,19 +1055,19 @@ static int sync_serial_ioctl(struct file *file,
 }
 
 static long sync_serial_ioctl(struct file *file,
-                             unsigned int cmd, unsigned long arg)
+               unsigned int cmd, unsigned long arg)
 {
-       long ret;
+       long ret;
 
-       mutex_lock(&sync_serial_mutex);
-       ret = sync_serial_ioctl_unlocked(file, cmd, arg);
-       mutex_unlock(&sync_serial_mutex);
+       mutex_lock(&sync_serial_mutex);
+       ret = sync_serial_ioctl_unlocked(file, cmd, arg);
+       mutex_unlock(&sync_serial_mutex);
 
-       return ret;
+       return ret;
 }
 
 /* NOTE: sync_serial_write does not support concurrency */
-static ssize_t sync_serial_write(struct file *file, const char *buf,
+static ssize_t sync_serial_write(struct file *file, const char __user *buf,
                                 size_t count, loff_t *ppos)
 {
        int dev = iminor(file_inode(file));
@@ -993,7 +1083,7 @@ static ssize_t sync_serial_write(struct file *file, const char *buf,
        unsigned char *buf_stop_ptr; /* Last byte + 1 */
 
        if (dev < 0 || dev >= NBR_PORTS || !ports[dev].enabled) {
-               DEBUG(printk("Invalid minor %d\n", dev));
+               DEBUG(pr_info("Invalid minor %d\n", dev));
                return -ENODEV;
        }
        port = &ports[dev];
@@ -1006,9 +1096,9 @@ static ssize_t sync_serial_write(struct file *file, const char *buf,
         * |_________|___________________|________________________|
         *           ^ rd_ptr            ^ wr_ptr
         */
-       DEBUGWRITE(printk(KERN_DEBUG "W d%d c %lu a: %p c: %p\n",
-                         port->port_nbr, count, port->active_tr_descr,
-                         port->catch_tr_descr));
+       DEBUGWRITE(pr_info("W d%d c %u a: %p c: %p\n",
+                          port->port_nbr, count, port->active_tr_descr,
+                          port->catch_tr_descr));
 
        /* Read variables that may be updated by interrupts */
        spin_lock_irqsave(&port->lock, flags);
@@ -1020,7 +1110,7 @@ static ssize_t sync_serial_write(struct file *file, const char *buf,
        if (port->tr_running &&
            ((port->use_dma && port->active_tr_descr == port->catch_tr_descr) ||
             out_buf_count >= OUT_BUFFER_SIZE)) {
-               DEBUGWRITE(printk(KERN_DEBUG "sser%d full\n", dev));
+               DEBUGWRITE(pr_info("sser%d full\n", dev));
                return -EAGAIN;
        }
 
@@ -1043,15 +1133,16 @@ static ssize_t sync_serial_write(struct file *file, const char *buf,
        if (copy_from_user(wr_ptr, buf, trunc_count))
                return -EFAULT;
 
-       DEBUGOUTBUF(printk(KERN_DEBUG "%-4d + %-4d = %-4d     %p %p %p\n",
-                          out_buf_count, trunc_count,
-                          port->out_buf_count, port->out_buffer,
-                          wr_ptr, buf_stop_ptr));
+       DEBUGOUTBUF(pr_info("%-4d + %-4d = %-4d     %p %p %p\n",
+                           out_buf_count, trunc_count,
+                           port->out_buf_count, port->out_buffer,
+                           wr_ptr, buf_stop_ptr));
 
        /* Make sure transmitter/receiver is running */
        if (!port->started) {
                reg_sser_rw_cfg cfg = REG_RD(sser, port->regi_sser, rw_cfg);
-               reg_sser_rw_rec_cfg rec_cfg = REG_RD(sser, port->regi_sser, rw_rec_cfg);
+               reg_sser_rw_rec_cfg rec_cfg =
+                       REG_RD(sser, port->regi_sser, rw_rec_cfg);
                cfg.en = regk_sser_yes;
                rec_cfg.rec_en = port->input;
                REG_WR(sser, port->regi_sser, rw_cfg, cfg);
@@ -1068,8 +1159,11 @@ static ssize_t sync_serial_write(struct file *file, const char *buf,
        spin_lock_irqsave(&port->lock, flags);
        port->out_buf_count += trunc_count;
        if (port->use_dma) {
+#ifdef SYNC_SER_DMA
                start_dma_out(port, wr_ptr, trunc_count);
+#endif
        } else if (!port->tr_running) {
+#ifdef SYNC_SER_MANUAL
                reg_sser_rw_intr_mask intr_mask;
                intr_mask = REG_RD(sser, port->regi_sser, rw_intr_mask);
                /* Start sender by writing data */
@@ -1077,14 +1171,15 @@ static ssize_t sync_serial_write(struct file *file, const char *buf,
                /* and enable transmitter ready IRQ */
                intr_mask.trdy = 1;
                REG_WR(sser, port->regi_sser, rw_intr_mask, intr_mask);
+#endif
        }
        spin_unlock_irqrestore(&port->lock, flags);
 
        /* Exit if non blocking */
        if (file->f_flags & O_NONBLOCK) {
-               DEBUGWRITE(printk(KERN_DEBUG "w d%d c %lu  %08x\n",
-                                 port->port_nbr, trunc_count,
-                                 REG_RD_INT(dma, port->regi_dmaout, r_intr)));
+               DEBUGWRITE(pr_info("w d%d c %u  %08x\n",
+                                  port->port_nbr, trunc_count,
+                                  REG_RD_INT(dma, port->regi_dmaout, r_intr)));
                return trunc_count;
        }
 
@@ -1094,105 +1189,32 @@ static ssize_t sync_serial_write(struct file *file, const char *buf,
        if (signal_pending(current))
                return -EINTR;
 
-       DEBUGWRITE(printk(KERN_DEBUG "w d%d c %lu\n",
-                         port->port_nbr, trunc_count));
+       DEBUGWRITE(pr_info("w d%d c %u\n", port->port_nbr, trunc_count));
        return trunc_count;
 }
 
-static ssize_t sync_serial_read(struct file * file, char * buf,
+static ssize_t sync_serial_read(struct file *file, char __user *buf,
                                size_t count, loff_t *ppos)
 {
-       int dev = iminor(file_inode(file));
-       int avail;
-       sync_port *port;
-       unsigned char* start;
-       unsigned char* end;
-       unsigned long flags;
-
-       if (dev < 0 || dev >= NBR_PORTS || !ports[dev].enabled)
-       {
-               DEBUG(printk("Invalid minor %d\n", dev));
-               return -ENODEV;
-       }
-       port = &ports[dev];
-
-       DEBUGREAD(printk("R%d c %d ri %lu wi %lu /%lu\n", dev, count, port->readp - port->flip, port->writep - port->flip, port->in_buffer_size));
-
-       if (!port->started)
-       {
-               reg_sser_rw_cfg cfg = REG_RD(sser, port->regi_sser, rw_cfg);
-               reg_sser_rw_tr_cfg tr_cfg = REG_RD(sser, port->regi_sser, rw_tr_cfg);
-               reg_sser_rw_rec_cfg rec_cfg = REG_RD(sser, port->regi_sser, rw_rec_cfg);
-               cfg.en = regk_sser_yes;
-               tr_cfg.tr_en = regk_sser_yes;
-               rec_cfg.rec_en = regk_sser_yes;
-               REG_WR(sser, port->regi_sser, rw_cfg, cfg);
-               REG_WR(sser, port->regi_sser, rw_tr_cfg, tr_cfg);
-               REG_WR(sser, port->regi_sser, rw_rec_cfg, rec_cfg);
-               port->started = 1;
-       }
-
-       /* Calculate number of available bytes */
-       /* Save pointers to avoid that they are modified by interrupt */
-       spin_lock_irqsave(&port->lock, flags);
-       start = (unsigned char*)port->readp; /* cast away volatile */
-       end = (unsigned char*)port->writep;  /* cast away volatile */
-       spin_unlock_irqrestore(&port->lock, flags);
-       while ((start == end) && !port->full) /* No data */
-       {
-               DEBUGREAD(printk(KERN_DEBUG "&"));
-               if (file->f_flags & O_NONBLOCK)
-                       return -EAGAIN;
-
-               wait_event_interruptible(port->in_wait_q,
-                                        !(start == end && !port->full));
-               if (signal_pending(current))
-                       return -EINTR;
-
-               spin_lock_irqsave(&port->lock, flags);
-               start = (unsigned char*)port->readp; /* cast away volatile */
-               end = (unsigned char*)port->writep;  /* cast away volatile */
-               spin_unlock_irqrestore(&port->lock, flags);
-       }
-
-       /* Lazy read, never return wrapped data. */
-       if (port->full)
-               avail = port->in_buffer_size;
-       else if (end > start)
-               avail = end - start;
-       else
-               avail = port->flip + port->in_buffer_size - start;
-
-       count = count > avail ? avail : count;
-       if (copy_to_user(buf, start, count))
-               return -EFAULT;
-       /* Disable interrupts while updating readp */
-       spin_lock_irqsave(&port->lock, flags);
-       port->readp += count;
-       if (port->readp >= port->flip + port->in_buffer_size) /* Wrap? */
-               port->readp = port->flip;
-       port->full = 0;
-       spin_unlock_irqrestore(&port->lock, flags);
-       DEBUGREAD(printk("r %d\n", count));
-       return count;
+       return __sync_serial_read(file, buf, count, ppos, NULL);
 }
 
-static void send_word(sync_port* port)
+#ifdef SYNC_SER_MANUAL
+static void send_word(struct sync_port *port)
 {
        reg_sser_rw_tr_cfg tr_cfg = REG_RD(sser, port->regi_sser, rw_tr_cfg);
        reg_sser_rw_tr_data tr_data =  {0};
 
-       switch(tr_cfg.sample_size)
+       switch (tr_cfg.sample_size) {
+       case 8:
+               port->out_buf_count--;
+               tr_data.data = *port->out_rd_ptr++;
+               REG_WR(sser, port->regi_sser, rw_tr_data, tr_data);
+               if (port->out_rd_ptr >= port->out_buffer + OUT_BUFFER_SIZE)
+                       port->out_rd_ptr = port->out_buffer;
+               break;
+       case 12:
        {
-        case 8:
-                port->out_buf_count--;
-                tr_data.data = *port->out_rd_ptr++;
-                REG_WR(sser, port->regi_sser, rw_tr_data, tr_data);
-                if (port->out_rd_ptr >= port->out_buffer + OUT_BUFFER_SIZE)
-                        port->out_rd_ptr = port->out_buffer;
-                break;
-        case 12:
-        {
                int data = (*port->out_rd_ptr++) << 8;
                data |= *port->out_rd_ptr++;
                port->out_buf_count -= 2;
@@ -1200,8 +1222,8 @@ static void send_word(sync_port* port)
                REG_WR(sser, port->regi_sser, rw_tr_data, tr_data);
                if (port->out_rd_ptr >= port->out_buffer + OUT_BUFFER_SIZE)
                        port->out_rd_ptr = port->out_buffer;
+               break;
        }
-       break;
        case 16:
                port->out_buf_count -= 2;
                tr_data.data = *(unsigned short *)port->out_rd_ptr;
@@ -1233,27 +1255,28 @@ static void send_word(sync_port* port)
                break;
        }
 }
+#endif
 
-static void start_dma_out(struct sync_port *port,
-                         const char *data, int count)
+#ifdef SYNC_SER_DMA
+static void start_dma_out(struct sync_port *port, const char *data, int count)
 {
-       port->active_tr_descr->buf = (char *) virt_to_phys((char *) data);
+       port->active_tr_descr->buf = (char *)virt_to_phys((char *)data);
        port->active_tr_descr->after = port->active_tr_descr->buf + count;
        port->active_tr_descr->intr = 1;
 
        port->active_tr_descr->eol = 1;
        port->prev_tr_descr->eol = 0;
 
-       DEBUGTRDMA(printk(KERN_DEBUG "Inserting eolr:%p eol@:%p\n",
+       DEBUGTRDMA(pr_info("Inserting eolr:%p eol@:%p\n",
                port->prev_tr_descr, port->active_tr_descr));
        port->prev_tr_descr = port->active_tr_descr;
-       port->active_tr_descr = phys_to_virt((int) port->active_tr_descr->next);
+       port->active_tr_descr = phys_to_virt((int)port->active_tr_descr->next);
 
        if (!port->tr_running) {
                reg_sser_rw_tr_cfg tr_cfg = REG_RD(sser, port->regi_sser,
                        rw_tr_cfg);
 
-               port->out_context.next = 0;
+               port->out_context.next = NULL;
                port->out_context.saved_data =
                        (dma_descr_data *)virt_to_phys(port->prev_tr_descr);
                port->out_context.saved_data_buf = port->prev_tr_descr->buf;
@@ -1263,57 +1286,58 @@ static void start_dma_out(struct sync_port *port,
 
                tr_cfg.tr_en = regk_sser_yes;
                REG_WR(sser, port->regi_sser, rw_tr_cfg, tr_cfg);
-               DEBUGTRDMA(printk(KERN_DEBUG "dma s\n"););
+               DEBUGTRDMA(pr_info(KERN_INFO "dma s\n"););
        } else {
                DMA_CONTINUE_DATA(port->regi_dmaout);
-               DEBUGTRDMA(printk(KERN_DEBUG "dma c\n"););
+               DEBUGTRDMA(pr_info("dma c\n"););
        }
 
        port->tr_running = 1;
 }
 
-static void start_dma_in(sync_port *port)
+static void start_dma_in(struct sync_port *port)
 {
        int i;
        char *buf;
+       unsigned long flags;
+       spin_lock_irqsave(&port->lock, flags);
        port->writep = port->flip;
+       spin_unlock_irqrestore(&port->lock, flags);
 
-       if (port->writep > port->flip + port->in_buffer_size) {
-               panic("Offset too large in sync serial driver\n");
-               return;
-       }
-       buf = (char*)virt_to_phys(port->in_buffer);
+       buf = (char *)virt_to_phys(port->in_buffer);
        for (i = 0; i < NBR_IN_DESCR; i++) {
                port->in_descr[i].buf = buf;
                port->in_descr[i].after = buf + port->inbufchunk;
                port->in_descr[i].intr = 1;
-               port->in_descr[i].next = (dma_descr_data*)virt_to_phys(&port->in_descr[i+1]);
+               port->in_descr[i].next =
+                       (dma_descr_data *)virt_to_phys(&port->in_descr[i+1]);
                port->in_descr[i].buf = buf;
                buf += port->inbufchunk;
        }
        /* Link the last descriptor to the first */
-       port->in_descr[i-1].next = (dma_descr_data*)virt_to_phys(&port->in_descr[0]);
+       port->in_descr[i-1].next =
+               (dma_descr_data *)virt_to_phys(&port->in_descr[0]);
        port->in_descr[i-1].eol = regk_sser_yes;
        port->next_rx_desc = &port->in_descr[0];
        port->prev_rx_desc = &port->in_descr[NBR_IN_DESCR - 1];
-       port->in_context.saved_data = (dma_descr_data*)virt_to_phys(&port->in_descr[0]);
+       port->in_context.saved_data =
+               (dma_descr_data *)virt_to_phys(&port->in_descr[0]);
        port->in_context.saved_data_buf = port->in_descr[0].buf;
        DMA_START_CONTEXT(port->regi_dmain, virt_to_phys(&port->in_context));
 }
 
-#ifdef SYNC_SER_DMA
 static irqreturn_t tr_interrupt(int irq, void *dev_id)
 {
        reg_dma_r_masked_intr masked;
-       reg_dma_rw_ack_intr ack_intr = {.data = regk_dma_yes};
+       reg_dma_rw_ack_intr ack_intr = { .data = regk_dma_yes };
        reg_dma_rw_stat stat;
        int i;
        int found = 0;
        int stop_sser = 0;
 
        for (i = 0; i < NBR_PORTS; i++) {
-               sync_port *port = &ports[i];
-               if (!port->enabled  || !port->use_dma)
+               struct sync_port *port = &ports[i];
+               if (!port->enabled || !port->use_dma)
                        continue;
 
                /* IRQ active for the port? */
@@ -1338,19 +1362,20 @@ static irqreturn_t tr_interrupt(int irq, void *dev_id)
                        int sent;
                        sent = port->catch_tr_descr->after -
                                port->catch_tr_descr->buf;
-                       DEBUGTXINT(printk(KERN_DEBUG "%-4d - %-4d = %-4d\t"
-                                         "in descr %p (ac: %p)\n",
-                                         port->out_buf_count, sent,
-                                         port->out_buf_count - sent,
-                                         port->catch_tr_descr,
-                                         port->active_tr_descr););
+                       DEBUGTXINT(pr_info("%-4d - %-4d = %-4d\t"
+                                          "in descr %p (ac: %p)\n",
+                                          port->out_buf_count, sent,
+                                          port->out_buf_count - sent,
+                                          port->catch_tr_descr,
+                                          port->active_tr_descr););
                        port->out_buf_count -= sent;
                        port->catch_tr_descr =
                                phys_to_virt((int) port->catch_tr_descr->next);
                        port->out_rd_ptr =
                                phys_to_virt((int) port->catch_tr_descr->buf);
                } else {
-                       int i, sent;
+                       reg_sser_rw_tr_cfg tr_cfg;
+                       int j, sent;
                        /* EOL handler.
                         * Note that if an EOL was encountered during the irq
                         * locked section of sync_ser_write the DMA will be
@@ -1358,11 +1383,11 @@ static irqreturn_t tr_interrupt(int irq, void *dev_id)
                         * The remaining descriptors will be traversed by
                         * the descriptor interrupts as usual.
                         */
-                       i = 0;
+                       j = 0;
                        while (!port->catch_tr_descr->eol) {
                                sent = port->catch_tr_descr->after -
                                        port->catch_tr_descr->buf;
-                               DEBUGOUTBUF(printk(KERN_DEBUG
+                               DEBUGOUTBUF(pr_info(
                                        "traversing descr %p -%d (%d)\n",
                                        port->catch_tr_descr,
                                        sent,
@@ -1370,16 +1395,15 @@ static irqreturn_t tr_interrupt(int irq, void *dev_id)
                                port->out_buf_count -= sent;
                                port->catch_tr_descr = phys_to_virt(
                                        (int)port->catch_tr_descr->next);
-                               i++;
-                               if (i >= NBR_OUT_DESCR) {
+                               j++;
+                               if (j >= NBR_OUT_DESCR) {
                                        /* TODO: Reset and recover */
                                        panic("sync_serial: missing eol");
                                }
                        }
                        sent = port->catch_tr_descr->after -
                                port->catch_tr_descr->buf;
-                       DEBUGOUTBUF(printk(KERN_DEBUG
-                               "eol at descr %p -%d (%d)\n",
+                       DEBUGOUTBUF(pr_info("eol at descr %p -%d (%d)\n",
                                port->catch_tr_descr,
                                sent,
                                port->out_buf_count));
@@ -1394,15 +1418,13 @@ static irqreturn_t tr_interrupt(int irq, void *dev_id)
                                        OUT_BUFFER_SIZE)
                                port->out_rd_ptr = port->out_buffer;
 
-                       reg_sser_rw_tr_cfg tr_cfg =
-                               REG_RD(sser, port->regi_sser, rw_tr_cfg);
-                       DEBUGTXINT(printk(KERN_DEBUG
+                       tr_cfg = REG_RD(sser, port->regi_sser, rw_tr_cfg);
+                       DEBUGTXINT(pr_info(
                                "tr_int DMA stop %d, set catch @ %p\n",
                                port->out_buf_count,
                                port->active_tr_descr));
                        if (port->out_buf_count != 0)
-                               printk(KERN_CRIT "sync_ser: buffer not "
-                                       "empty after eol.\n");
+                               pr_err("sync_ser: buf not empty after eol\n");
                        port->catch_tr_descr = port->active_tr_descr;
                        port->tr_running = 0;
                        tr_cfg.tr_en = regk_sser_no;
@@ -1414,62 +1436,79 @@ static irqreturn_t tr_interrupt(int irq, void *dev_id)
        return IRQ_RETVAL(found);
 } /* tr_interrupt */
 
+
+static inline void handle_rx_packet(struct sync_port *port)
+{
+       int idx;
+       reg_dma_rw_ack_intr ack_intr = { .data = regk_dma_yes };
+       unsigned long flags;
+
+       DEBUGRXINT(pr_info(KERN_INFO "!"));
+       spin_lock_irqsave(&port->lock, flags);
+
+       /* If we overrun the user experience is crap regardless if we
+        * drop new or old data. Its much easier to get it right when
+        * dropping new data so lets do that.
+        */
+       if ((port->writep + port->inbufchunk <=
+            port->flip + port->in_buffer_size) &&
+           (port->in_buffer_len + port->inbufchunk < IN_BUFFER_SIZE)) {
+               memcpy(port->writep,
+                      phys_to_virt((unsigned)port->next_rx_desc->buf),
+                      port->inbufchunk);
+               port->writep += port->inbufchunk;
+               if (port->writep >= port->flip + port->in_buffer_size)
+                       port->writep = port->flip;
+
+               /* Timestamp the new data chunk. */
+               if (port->write_ts_idx == NBR_IN_DESCR)
+                       port->write_ts_idx = 0;
+               idx = port->write_ts_idx++;
+               do_posix_clock_monotonic_gettime(&port->timestamp[idx]);
+               port->in_buffer_len += port->inbufchunk;
+       }
+       spin_unlock_irqrestore(&port->lock, flags);
+
+       port->next_rx_desc->eol = 1;
+       port->prev_rx_desc->eol = 0;
+       /* Cache bug workaround */
+       flush_dma_descr(port->prev_rx_desc, 0);
+       port->prev_rx_desc = port->next_rx_desc;
+       port->next_rx_desc = phys_to_virt((unsigned)port->next_rx_desc->next);
+       /* Cache bug workaround */
+       flush_dma_descr(port->prev_rx_desc, 1);
+       /* wake up the waiting process */
+       wake_up_interruptible(&port->in_wait_q);
+       DMA_CONTINUE(port->regi_dmain);
+       REG_WR(dma, port->regi_dmain, rw_ack_intr, ack_intr);
+
+}
+
 static irqreturn_t rx_interrupt(int irq, void *dev_id)
 {
        reg_dma_r_masked_intr masked;
-       reg_dma_rw_ack_intr ack_intr = {.data = regk_dma_yes};
 
        int i;
        int found = 0;
 
-       for (i = 0; i < NBR_PORTS; i++)
-       {
-               sync_port *port = &ports[i];
+       DEBUG(pr_info("rx_interrupt\n"));
+
+       for (i = 0; i < NBR_PORTS; i++) {
+               struct sync_port *port = &ports[i];
 
-               if (!port->enabled || !port->use_dma )
+               if (!port->enabled || !port->use_dma)
                        continue;
 
                masked = REG_RD(dma, port->regi_dmain, r_masked_intr);
 
-               if (masked.data) /* Descriptor interrupt */
-               {
-                       found = 1;
-                       while (REG_RD(dma, port->regi_dmain, rw_data) !=
-                              virt_to_phys(port->next_rx_desc)) {
-                               DEBUGRXINT(printk(KERN_DEBUG "!"));
-                               if (port->writep + port->inbufchunk > port->flip + port->in_buffer_size) {
-                                       int first_size = port->flip + port->in_buffer_size - port->writep;
-                                       memcpy((char*)port->writep, phys_to_virt((unsigned)port->next_rx_desc->buf), first_size);
-                                       memcpy(port->flip, phys_to_virt((unsigned)port->next_rx_desc->buf+first_size), port->inbufchunk - first_size);
-                                       port->writep = port->flip + port->inbufchunk - first_size;
-                               } else {
-                                       memcpy((char*)port->writep,
-                                              phys_to_virt((unsigned)port->next_rx_desc->buf),
-                                              port->inbufchunk);
-                                       port->writep += port->inbufchunk;
-                                       if (port->writep >= port->flip + port->in_buffer_size)
-                                               port->writep = port->flip;
-                               }
-                                if (port->writep == port->readp)
-                                {
-                                 port->full = 1;
-                                }
-
-                               port->next_rx_desc->eol = 1;
-                               port->prev_rx_desc->eol = 0;
-                               /* Cache bug workaround */
-                               flush_dma_descr(port->prev_rx_desc, 0);
-                               port->prev_rx_desc = port->next_rx_desc;
-                               port->next_rx_desc = phys_to_virt((unsigned)port->next_rx_desc->next);
-                               /* Cache bug workaround */
-                               flush_dma_descr(port->prev_rx_desc, 1);
-                               /* wake up the waiting process */
-                               wake_up_interruptible(&port->in_wait_q);
-                               DMA_CONTINUE(port->regi_dmain);
-                               REG_WR(dma, port->regi_dmain, rw_ack_intr, ack_intr);
+               if (!masked.data)
+                       continue;
 
-                       }
-               }
+               /* Descriptor interrupt */
+               found = 1;
+               while (REG_RD(dma, port->regi_dmain, rw_data) !=
+                               virt_to_phys(port->next_rx_desc))
+                       handle_rx_packet(port);
        }
        return IRQ_RETVAL(found);
 } /* rx_interrupt */
@@ -1478,75 +1517,83 @@ static irqreturn_t rx_interrupt(int irq, void *dev_id)
 #ifdef SYNC_SER_MANUAL
 static irqreturn_t manual_interrupt(int irq, void *dev_id)
 {
+       unsigned long flags;
        int i;
        int found = 0;
        reg_sser_r_masked_intr masked;
 
-       for (i = 0; i < NBR_PORTS; i++)
-       {
-               sync_port *port = &ports[i];
+       for (i = 0; i < NBR_PORTS; i++) {
+               struct sync_port *port = &ports[i];
 
                if (!port->enabled || port->use_dma)
-               {
                        continue;
-               }
 
                masked = REG_RD(sser, port->regi_sser, r_masked_intr);
-               if (masked.rdav)        /* Data received? */
-               {
-                       reg_sser_rw_rec_cfg rec_cfg = REG_RD(sser, port->regi_sser, rw_rec_cfg);
-                       reg_sser_r_rec_data data = REG_RD(sser, port->regi_sser, r_rec_data);
+               /* Data received? */
+               if (masked.rdav) {
+                       reg_sser_rw_rec_cfg rec_cfg =
+                               REG_RD(sser, port->regi_sser, rw_rec_cfg);
+                       reg_sser_r_rec_data data = REG_RD(sser,
+                               port->regi_sser, r_rec_data);
                        found = 1;
                        /* Read data */
-                       switch(rec_cfg.sample_size)
-                       {
+                       spin_lock_irqsave(&port->lock, flags);
+                       switch (rec_cfg.sample_size) {
                        case 8:
                                *port->writep++ = data.data & 0xff;
                                break;
                        case 12:
                                *port->writep = (data.data & 0x0ff0) >> 4;
                                *(port->writep + 1) = data.data & 0x0f;
-                               port->writep+=2;
+                               port->writep += 2;
                                break;
                        case 16:
-                               *(unsigned short*)port->writep = data.data;
-                               port->writep+=2;
+                               *(unsigned short *)port->writep = data.data;
+                               port->writep += 2;
                                break;
                        case 24:
-                               *(unsigned int*)port->writep = data.data;
-                               port->writep+=3;
+                               *(unsigned int *)port->writep = data.data;
+                               port->writep += 3;
                                break;
                        case 32:
-                               *(unsigned int*)port->writep = data.data;
-                               port->writep+=4;
+                               *(unsigned int *)port->writep = data.data;
+                               port->writep += 4;
                                break;
                        }
 
-                       if (port->writep >= port->flip + port->in_buffer_size) /* Wrap? */
+                       /* Wrap? */
+                       if (port->writep >= port->flip + port->in_buffer_size)
                                port->writep = port->flip;
                        if (port->writep == port->readp) {
-                               /* receive buffer overrun, discard oldest data
-                                */
+                               /* Receive buf overrun, discard oldest data */
                                port->readp++;
-                               if (port->readp >= port->flip + port->in_buffer_size) /* Wrap? */
+                               /* Wrap? */
+                               if (port->readp >= port->flip +
+                                               port->in_buffer_size)
                                        port->readp = port->flip;
                        }
+                       spin_unlock_irqrestore(&port->lock, flags);
                        if (sync_data_avail(port) >= port->inbufchunk)
-                               wake_up_interruptible(&port->in_wait_q); /* Wake up application */
+                               /* Wake up application */
+                               wake_up_interruptible(&port->in_wait_q);
                }
 
-               if (masked.trdy) /* Transmitter ready? */
-               {
+               /* Transmitter ready? */
+               if (masked.trdy) {
                        found = 1;
-                       if (port->out_buf_count > 0) /* More data to send */
+                       /* More data to send */
+                       if (port->out_buf_count > 0)
                                send_word(port);
-                       else /* transmission finished */
-                       {
+                       else {
+                               /* Transmission finished */
                                reg_sser_rw_intr_mask intr_mask;
-                               intr_mask = REG_RD(sser, port->regi_sser, rw_intr_mask);
+                               intr_mask = REG_RD(sser, port->regi_sser,
+                                       rw_intr_mask);
                                intr_mask.trdy = 0;
-                               REG_WR(sser, port->regi_sser, rw_intr_mask, intr_mask);
-                               wake_up_interruptible(&port->out_wait_q); /* Wake up application */
+                               REG_WR(sser, port->regi_sser,
+                                       rw_intr_mask, intr_mask);
+                               /* Wake up application */
+                               wake_up_interruptible(&port->out_wait_q);
                        }
                }
        }
@@ -1554,4 +1601,109 @@ static irqreturn_t manual_interrupt(int irq, void *dev_id)
 }
 #endif
 
+static int __init etrax_sync_serial_init(void)
+{
+#if 1
+       /* This code will be removed when we move to udev for all devices. */
+       syncser_first = MKDEV(SYNC_SERIAL_MAJOR, 0);
+       if (register_chrdev_region(syncser_first, minor_count, SYNCSER_NAME)) {
+               pr_err("Failed to register major %d\n", SYNC_SERIAL_MAJOR);
+               return -1;
+       }
+#else
+       /* Allocate dynamic major number. */
+       if (alloc_chrdev_region(&syncser_first, 0, minor_count, SYNCSER_NAME)) {
+               pr_err("Failed to allocate character device region\n");
+               return -1;
+       }
+#endif
+       syncser_cdev = cdev_alloc();
+       if (!syncser_cdev) {
+               pr_err("Failed to allocate cdev for syncser\n");
+               unregister_chrdev_region(syncser_first, minor_count);
+               return -1;
+       }
+       cdev_init(syncser_cdev, &syncser_fops);
+
+       /* Create a sysfs class for syncser */
+       syncser_class = class_create(THIS_MODULE, "syncser_class");
+
+       /* Initialize Ports */
+#if defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL_PORT0)
+       if (artpec_pinmux_alloc_fixed(PINMUX_SSER0)) {
+               pr_warn("Unable to alloc pins for synchronous serial port 0\n");
+               unregister_chrdev_region(syncser_first, minor_count);
+               return -EIO;
+       }
+       initialize_port(0);
+       ports[0].enabled = 1;
+       /* Register with sysfs so udev can pick it up. */
+       device_create(syncser_class, NULL, syncser_first, NULL,
+                     "%s%d", SYNCSER_NAME, 0);
+#endif
+
+#if defined(CONFIG_ETRAXFS) && defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL_PORT1)
+       if (artpec_pinmux_alloc_fixed(PINMUX_SSER1)) {
+               pr_warn("Unable to alloc pins for synchronous serial port 1\n");
+               unregister_chrdev_region(syncser_first, minor_count);
+               class_destroy(syncser_class);
+               return -EIO;
+       }
+       initialize_port(1);
+       ports[1].enabled = 1;
+       /* Register with sysfs so udev can pick it up. */
+       device_create(syncser_class, NULL, syncser_first, NULL,
+                     "%s%d", SYNCSER_NAME, 0);
+#endif
+
+       /* Add it to system */
+       if (cdev_add(syncser_cdev, syncser_first, minor_count) < 0) {
+               pr_err("Failed to add syncser as char device\n");
+               device_destroy(syncser_class, syncser_first);
+               class_destroy(syncser_class);
+               cdev_del(syncser_cdev);
+               unregister_chrdev_region(syncser_first, minor_count);
+               return -1;
+       }
+
+
+       pr_info("ARTPEC synchronous serial port (%s: %d, %d)\n",
+               SYNCSER_NAME, MAJOR(syncser_first), MINOR(syncser_first));
+
+       return 0;
+}
+
+static void __exit etrax_sync_serial_exit(void)
+{
+       int i;
+       device_destroy(syncser_class, syncser_first);
+       class_destroy(syncser_class);
+
+       if (syncser_cdev) {
+               cdev_del(syncser_cdev);
+               unregister_chrdev_region(syncser_first, minor_count);
+       }
+       for (i = 0; i < NBR_PORTS; i++) {
+               struct sync_port *port = &ports[i];
+               if (port->init_irqs == dma_irq_setup) {
+                       /* Free dma irqs and dma channels. */
+#ifdef SYNC_SER_DMA
+                       artpec_free_dma(port->dma_in_nbr);
+                       artpec_free_dma(port->dma_out_nbr);
+                       free_irq(port->dma_out_intr_vect, port);
+                       free_irq(port->dma_in_intr_vect, port);
+#endif
+               } else if (port->init_irqs == manual_irq_setup) {
+                       /* Free manual irq. */
+                       free_irq(port->syncser_intr_vect, port);
+               }
+       }
+
+       pr_info("ARTPEC synchronous serial port unregistered\n");
+}
+
 module_init(etrax_sync_serial_init);
+module_exit(etrax_sync_serial_exit);
+
+MODULE_LICENSE("GPL");
+