2 * mrst_max3110.c - spi uart protocol driver for Maxim 3110
4 * Copyright (c) 2008-2010, Intel Corporation.
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms and conditions of the GNU General Public License,
8 * version 2, as published by the Free Software Foundation.
10 * This program is distributed in the hope it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
15 * You should have received a copy of the GNU General Public License along with
16 * this program; if not, write to the Free Software Foundation, Inc.,
17 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
22 * 1. From Max3110 spec, the Rx FIFO has 8 words, while the Tx FIFO only has
23 * 1 word. If SPI master controller doesn't support sclk frequency change,
24 * then the char need be sent out one by one with some delay
26 * 2. Currently only RX available interrrupt is used, no need for waiting TXE
27 * interrupt for a low speed UART device
30 #include <linux/module.h>
31 #include <linux/ioport.h>
32 #include <linux/irq.h>
33 #include <linux/init.h>
34 #include <linux/console.h>
35 #include <linux/tty.h>
36 #include <linux/tty_flip.h>
37 #include <linux/serial_core.h>
38 #include <linux/serial_reg.h>
40 #include <linux/kthread.h>
41 #include <linux/spi/spi.h>
43 #include "mrst_max3110.h"
45 #define PR_FMT "mrst_max3110: "
47 #define UART_TX_NEEDED 1
48 #define CON_TX_NEEDED 2
49 #define BIT_IRQ_PENDING 3
52 struct uart_port port;
53 struct spi_device *spi;
54 char name[SPI_NAME_SIZE];
57 struct task_struct *main_thread;
58 struct task_struct *read_thread;
59 struct mutex thread_mutex;
64 u8 parity, word_7bits;
67 unsigned long uart_flags;
70 struct circ_buf con_xmit;
73 /* global data structure, may need be removed */
74 static struct uart_max3110 *pmax;
76 static void receive_chars(struct uart_max3110 *max,
77 unsigned char *str, int len);
78 static int max3110_read_multi(struct uart_max3110 *max, u8 *buf);
79 static void max3110_con_receive(struct uart_max3110 *max);
81 static int max3110_write_then_read(struct uart_max3110 *max,
82 const void *txbuf, void *rxbuf, unsigned len, int always_fast)
84 struct spi_device *spi = max->spi;
85 struct spi_message message;
86 struct spi_transfer x;
89 spi_message_init(&message);
90 memset(&x, 0, sizeof x);
94 spi_message_add_tail(&x, &message);
97 x.speed_hz = spi->max_speed_hz;
99 x.speed_hz = max->baud;
102 ret = spi_sync(spi, &message);
106 /* Write a 16b word to the device */
107 static int max3110_out(struct uart_max3110 *max, const u16 out)
114 buf = kzalloc(8, GFP_KERNEL | GFP_DMA);
121 ret = max3110_write_then_read(max, obuf, ibuf, 2, 1);
123 pr_warning(PR_FMT "%s(): get err msg %d when sending 0x%x\n",
128 /* If some valid data is read back */
129 if (*ibuf & MAX3110_READ_DATA_AVAILABLE) {
131 receive_chars(max, &ch, 1);
140 * This is usually used to read data from SPIC RX FIFO, which doesn't
141 * need any delay like flushing character out.
143 * Return how many valide bytes are read back
145 static int max3110_read_multi(struct uart_max3110 *max, u8 *rxbuf)
149 u8 *pbuf, valid_str[M3110_RX_FIFO_DEPTH];
152 blen = M3110_RX_FIFO_DEPTH * sizeof(u16);
153 buf = kzalloc(blen * 2, GFP_KERNEL | GFP_DMA);
155 pr_warning(PR_FMT "%s(): fail to alloc dma buffer\n", __func__);
159 /* tx/rx always have the same length */
163 if (max3110_write_then_read(max, obuf, ibuf, blen, 1)) {
168 /* If caller doesn't provide a buffer, then handle received char */
169 pbuf = rxbuf ? rxbuf : valid_str;
171 for (i = 0, j = 0; i < M3110_RX_FIFO_DEPTH; i++) {
172 if (ibuf[i] & MAX3110_READ_DATA_AVAILABLE)
173 pbuf[j++] = ibuf[i] & 0xff;
176 if (j && (pbuf == valid_str))
177 receive_chars(max, valid_str, j);
183 static void serial_m3110_con_putchar(struct uart_port *port, int ch)
185 struct uart_max3110 *max =
186 container_of(port, struct uart_max3110, port);
187 struct circ_buf *xmit = &max->con_xmit;
189 if (uart_circ_chars_free(xmit)) {
190 xmit->buf[xmit->head] = (char)ch;
191 xmit->head = (xmit->head + 1) & (PAGE_SIZE - 1);
196 * Print a string to the serial port trying not to disturb
197 * any possible real use of the port...
199 * The console_lock must be held when we get here.
201 static void serial_m3110_con_write(struct console *co,
202 const char *s, unsigned int count)
207 uart_console_write(&pmax->port, s, count, serial_m3110_con_putchar);
209 if (!test_and_set_bit(CON_TX_NEEDED, &pmax->uart_flags))
210 wake_up_process(pmax->main_thread);
214 serial_m3110_con_setup(struct console *co, char *options)
216 struct uart_max3110 *max = pmax;
222 pr_info(PR_FMT "setting up console\n");
228 pr_err(PR_FMT "pmax is NULL, return");
233 uart_parse_options(options, &baud, &parity, &bits, &flow);
235 return uart_set_options(&max->port, co, baud, parity, bits, flow);
238 static struct tty_driver *serial_m3110_con_device(struct console *co,
241 struct uart_driver *p = co->data;
243 return p->tty_driver;
246 static struct uart_driver serial_m3110_reg;
247 static struct console serial_m3110_console = {
249 .write = serial_m3110_con_write,
250 .device = serial_m3110_con_device,
251 .setup = serial_m3110_con_setup,
252 .flags = CON_PRINTBUFFER,
254 .data = &serial_m3110_reg,
257 static unsigned int serial_m3110_tx_empty(struct uart_port *port)
262 static void serial_m3110_stop_tx(struct uart_port *port)
267 /* stop_rx will be called in spin_lock env */
268 static void serial_m3110_stop_rx(struct uart_port *port)
273 #define WORDS_PER_XFER 128
274 static void send_circ_buf(struct uart_max3110 *max,
275 struct circ_buf *xmit)
279 u8 valid_str[WORDS_PER_XFER];
280 int i, j, len, blen, dma_size, left, ret = 0;
283 dma_size = WORDS_PER_XFER * sizeof(u16) * 2;
284 buf = kzalloc(dma_size, GFP_KERNEL | GFP_DMA);
288 ibuf = buf + dma_size/2;
290 while (!uart_circ_empty(xmit)) {
291 left = uart_circ_chars_pending(xmit);
293 len = min(left, WORDS_PER_XFER);
294 blen = len * sizeof(u16);
295 memset(ibuf, 0, blen);
297 for (i = 0; i < len; i++) {
298 obuf[i] = (u8)xmit->buf[xmit->tail] | WD_TAG;
299 xmit->tail = (xmit->tail + 1) &
300 (UART_XMIT_SIZE - 1);
303 /* Fail to send msg to console is not very critical */
304 ret = max3110_write_then_read(max, obuf, ibuf, blen, 0);
306 pr_warning(PR_FMT "%s(): get err msg %d\n",
309 for (i = 0, j = 0; i < len; i++) {
310 if (ibuf[i] & MAX3110_READ_DATA_AVAILABLE)
311 valid_str[j++] = ibuf[i] & 0xff;
315 receive_chars(max, valid_str, j);
317 max->port.icount.tx += len;
325 static void transmit_char(struct uart_max3110 *max)
327 struct uart_port *port = &max->port;
328 struct circ_buf *xmit = &port->state->xmit;
330 if (uart_circ_empty(xmit) || uart_tx_stopped(port))
333 send_circ_buf(max, xmit);
335 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
336 uart_write_wakeup(port);
338 if (uart_circ_empty(xmit))
339 serial_m3110_stop_tx(port);
343 * This will be called by uart_write() and tty_write, can't
346 static void serial_m3110_start_tx(struct uart_port *port)
348 struct uart_max3110 *max =
349 container_of(port, struct uart_max3110, port);
351 if (!test_and_set_bit(UART_TX_NEEDED, &max->uart_flags))
352 wake_up_process(max->main_thread);
355 static void receive_chars(struct uart_max3110 *max, unsigned char *str, int len)
357 struct uart_port *port = &max->port;
358 struct tty_struct *tty;
361 /* If uart is not opened, just return */
365 tty = port->state->port.tty;
370 usable = tty_buffer_request_room(tty, len);
372 tty_insert_flip_string(tty, str, usable);
374 port->icount.rx += usable;
378 tty_flip_buffer_push(tty);
382 * This routine will be used in read_thread or RX IRQ handling,
383 * it will first do one round buffer read(8 words), if there is some
384 * valid RX data, will try to read 5 more rounds till all data
387 * Use stack space as data buffer to save some system load, and chose
388 * 504 Btyes as a threadhold to do a bulk push to upper tty layer when
389 * receiving bulk data, a much bigger buffer may cause stack overflow
391 static void max3110_con_receive(struct uart_max3110 *max)
393 int loop = 1, num, total = 0;
394 u8 recv_buf[512], *pbuf;
398 num = max3110_read_multi(max, pbuf);
406 receive_chars(max, recv_buf, total);
414 receive_chars(max, recv_buf, total);
417 static int max3110_main_thread(void *_max)
419 struct uart_max3110 *max = _max;
420 wait_queue_head_t *wq = &max->wq;
422 struct circ_buf *xmit = &max->con_xmit;
424 pr_info(PR_FMT "start main thread\n");
427 wait_event_interruptible(*wq, max->uart_flags || kthread_should_stop());
429 mutex_lock(&max->thread_mutex);
431 if (test_and_clear_bit(BIT_IRQ_PENDING, &max->uart_flags))
432 max3110_con_receive(max);
434 /* first handle console output */
435 if (test_and_clear_bit(CON_TX_NEEDED, &max->uart_flags))
436 send_circ_buf(max, xmit);
438 /* handle uart output */
439 if (test_and_clear_bit(UART_TX_NEEDED, &max->uart_flags))
442 mutex_unlock(&max->thread_mutex);
444 } while (!kthread_should_stop());
449 static irqreturn_t serial_m3110_irq(int irq, void *dev_id)
451 struct uart_max3110 *max = dev_id;
453 /* max3110's irq is a falling edge, not level triggered,
454 * so no need to disable the irq */
455 if (!test_and_set_bit(BIT_IRQ_PENDING, &max->uart_flags))
456 wake_up_process(max->main_thread);
461 /* if don't use RX IRQ, then need a thread to polling read */
462 static int max3110_read_thread(void *_max)
464 struct uart_max3110 *max = _max;
466 pr_info(PR_FMT "start read thread\n");
469 * If can't acquire the mutex, it means the main thread
470 * is running which will also perform the rx job
472 if (mutex_trylock(&max->thread_mutex)) {
473 max3110_con_receive(max);
474 mutex_unlock(&max->thread_mutex);
477 set_current_state(TASK_INTERRUPTIBLE);
478 schedule_timeout(HZ / 20);
479 } while (!kthread_should_stop());
484 static int serial_m3110_startup(struct uart_port *port)
486 struct uart_max3110 *max =
487 container_of(port, struct uart_max3110, port);
491 if (port->line != 0) {
492 pr_err(PR_FMT "uart port startup failed\n");
496 /* Disable all IRQ and config it to 115200, 8n1 */
497 config = WC_TAG | WC_FIFO_ENABLE
502 /* as we use thread to handle tx/rx, need set low latency */
503 port->state->port.tty->low_latency = 1;
506 max->read_thread = NULL;
507 ret = request_irq(max->irq, serial_m3110_irq,
508 IRQ_TYPE_EDGE_FALLING, "max3110", max);
511 pr_err(PR_FMT "unable to allocate IRQ, polling\n");
513 /* Enable RX IRQ only */
514 config |= WC_RXA_IRQ_ENABLE;
519 /* If IRQ is disabled, start a read thread for input data */
521 kthread_run(max3110_read_thread, max, "max3110_read");
522 if (IS_ERR(max->read_thread)) {
523 ret = PTR_ERR(max->read_thread);
524 max->read_thread = NULL;
525 pr_err(PR_FMT "Can't create read thread!\n");
530 ret = max3110_out(max, config);
533 free_irq(max->irq, max);
534 if (max->read_thread)
535 kthread_stop(max->read_thread);
536 max->read_thread = NULL;
540 max->cur_conf = config;
544 static void serial_m3110_shutdown(struct uart_port *port)
546 struct uart_max3110 *max =
547 container_of(port, struct uart_max3110, port);
550 if (max->read_thread) {
551 kthread_stop(max->read_thread);
552 max->read_thread = NULL;
556 free_irq(max->irq, max);
558 /* Disable interrupts from this port */
559 config = WC_TAG | WC_SW_SHDI;
560 max3110_out(max, config);
563 static void serial_m3110_release_port(struct uart_port *port)
567 static int serial_m3110_request_port(struct uart_port *port)
572 static void serial_m3110_config_port(struct uart_port *port, int flags)
574 port->type = PORT_MAX3100;
578 serial_m3110_verify_port(struct uart_port *port, struct serial_struct *ser)
580 /* we don't want the core code to modify any port params */
585 static const char *serial_m3110_type(struct uart_port *port)
587 struct uart_max3110 *max =
588 container_of(port, struct uart_max3110, port);
593 serial_m3110_set_termios(struct uart_port *port, struct ktermios *termios,
594 struct ktermios *old)
596 struct uart_max3110 *max =
597 container_of(port, struct uart_max3110, port);
599 unsigned int baud, parity = 0;
601 u16 new_conf = max->cur_conf;
603 switch (termios->c_cflag & CSIZE) {
605 cval = UART_LCR_WLEN7;
606 new_conf |= WC_7BIT_WORD;
609 /* We only support CS7 & CS8 */
610 termios->c_cflag &= ~CSIZE;
611 termios->c_cflag |= CS8;
613 cval = UART_LCR_WLEN8;
614 new_conf |= WC_8BIT_WORD;
618 baud = uart_get_baud_rate(port, termios, old, 0, 230400);
620 /* First calc the div for 1.8MHZ clock case */
623 clk_div = WC_BAUD_DR384;
626 clk_div = WC_BAUD_DR192;
629 clk_div = WC_BAUD_DR96;
632 clk_div = WC_BAUD_DR48;
635 clk_div = WC_BAUD_DR24;
638 clk_div = WC_BAUD_DR12;
641 clk_div = WC_BAUD_DR6;
644 clk_div = WC_BAUD_DR3;
647 clk_div = WC_BAUD_DR2;
650 clk_div = WC_BAUD_DR1;
653 if (max->clock & MAX3110_HIGH_CLK)
656 /* Pick the previous baud rate */
658 clk_div = max->cur_conf & WC_BAUD_DIV_MASK;
659 tty_termios_encode_baud_rate(termios, baud, baud);
662 if (max->clock & MAX3110_HIGH_CLK) {
664 /* High clk version max3110 doesn't support B300 */
667 clk_div = WC_BAUD_DR384;
670 clk_div = WC_BAUD_DR1;
671 tty_termios_encode_baud_rate(termios, baud, baud);
674 new_conf = (new_conf & ~WC_BAUD_DIV_MASK) | clk_div;
676 if (unlikely(termios->c_cflag & CMSPAR))
677 termios->c_cflag &= ~CMSPAR;
679 if (termios->c_cflag & CSTOPB)
680 new_conf |= WC_2_STOPBITS;
682 new_conf &= ~WC_2_STOPBITS;
684 if (termios->c_cflag & PARENB) {
685 new_conf |= WC_PARITY_ENABLE;
686 parity |= UART_LCR_PARITY;
688 new_conf &= ~WC_PARITY_ENABLE;
690 if (!(termios->c_cflag & PARODD))
691 parity |= UART_LCR_EPAR;
692 max->parity = parity;
694 uart_update_timeout(port, termios->c_cflag, baud);
697 if (new_conf != max->cur_conf) {
698 if (!max3110_out(max, new_conf)) {
699 max->cur_conf = new_conf;
705 /* Don't handle hw handshaking */
706 static unsigned int serial_m3110_get_mctrl(struct uart_port *port)
708 return TIOCM_DSR | TIOCM_CAR | TIOCM_DSR;
711 static void serial_m3110_set_mctrl(struct uart_port *port, unsigned int mctrl)
715 static void serial_m3110_break_ctl(struct uart_port *port, int break_state)
719 static void serial_m3110_pm(struct uart_port *port, unsigned int state,
720 unsigned int oldstate)
724 static void serial_m3110_enable_ms(struct uart_port *port)
728 struct uart_ops serial_m3110_ops = {
729 .tx_empty = serial_m3110_tx_empty,
730 .set_mctrl = serial_m3110_set_mctrl,
731 .get_mctrl = serial_m3110_get_mctrl,
732 .stop_tx = serial_m3110_stop_tx,
733 .start_tx = serial_m3110_start_tx,
734 .stop_rx = serial_m3110_stop_rx,
735 .enable_ms = serial_m3110_enable_ms,
736 .break_ctl = serial_m3110_break_ctl,
737 .startup = serial_m3110_startup,
738 .shutdown = serial_m3110_shutdown,
739 .set_termios = serial_m3110_set_termios,
740 .pm = serial_m3110_pm,
741 .type = serial_m3110_type,
742 .release_port = serial_m3110_release_port,
743 .request_port = serial_m3110_request_port,
744 .config_port = serial_m3110_config_port,
745 .verify_port = serial_m3110_verify_port,
748 static struct uart_driver serial_m3110_reg = {
749 .owner = THIS_MODULE,
750 .driver_name = "MRST serial",
755 .cons = &serial_m3110_console,
759 static int serial_m3110_suspend(struct spi_device *spi, pm_message_t state)
761 struct uart_max3110 *max = spi_get_drvdata(spi);
763 disable_irq(max->irq);
764 uart_suspend_port(&serial_m3110_reg, &max->port);
765 max3110_out(max, max->cur_conf | WC_SW_SHDI);
769 static int serial_m3110_resume(struct spi_device *spi)
771 struct uart_max3110 *max = spi_get_drvdata(spi);
773 max3110_out(max, max->cur_conf);
774 uart_resume_port(&serial_m3110_reg, &max->port);
775 enable_irq(max->irq);
779 #define serial_m3110_suspend NULL
780 #define serial_m3110_resume NULL
783 static int __devinit serial_m3110_probe(struct spi_device *spi)
785 struct uart_max3110 *max;
790 max = kzalloc(sizeof(*max), GFP_KERNEL);
795 spi->bits_per_word = 16;
796 max->clock = MAX3110_HIGH_CLK;
800 max->port.type = PORT_MAX3100;
801 max->port.fifosize = 2; /* Only have 16b buffer */
802 max->port.ops = &serial_m3110_ops;
804 max->port.dev = &spi->dev;
805 max->port.uartclk = 115200;
808 strcpy(max->name, spi->modalias);
809 max->irq = (u16)spi->irq;
811 mutex_init(&max->thread_mutex);
820 /* Check if reading configuration register returns something sane */
823 ret = max3110_write_then_read(max, (u8 *)&res, (u8 *)&res, 2, 0);
824 if (ret < 0 || res == 0 || res == 0xffff) {
825 dev_dbg(&spi->dev, "MAX3111 deemed not present (conf reg %04x)",
831 buffer = (void *)__get_free_page(GFP_KERNEL);
836 max->con_xmit.buf = buffer;
837 max->con_xmit.head = 0;
838 max->con_xmit.tail = 0;
840 init_waitqueue_head(&max->wq);
842 max->main_thread = kthread_run(max3110_main_thread,
843 max, "max3110_main");
844 if (IS_ERR(max->main_thread)) {
845 ret = PTR_ERR(max->main_thread);
849 spi_set_drvdata(spi, max);
852 /* Give membase a psudo value to pass serial_core's check */
853 max->port.membase = (void *)0xff110000;
854 uart_add_one_port(&serial_m3110_reg, &max->port);
859 free_page((unsigned long)buffer);
865 static int __devexit serial_m3110_remove(struct spi_device *dev)
867 struct uart_max3110 *max = spi_get_drvdata(dev);
872 uart_remove_one_port(&serial_m3110_reg, &max->port);
874 free_page((unsigned long)max->con_xmit.buf);
876 if (max->main_thread)
877 kthread_stop(max->main_thread);
883 static struct spi_driver uart_max3110_driver = {
885 .name = "spi_max3111",
886 .bus = &spi_bus_type,
887 .owner = THIS_MODULE,
889 .probe = serial_m3110_probe,
890 .remove = __devexit_p(serial_m3110_remove),
891 .suspend = serial_m3110_suspend,
892 .resume = serial_m3110_resume,
895 static int __init serial_m3110_init(void)
899 ret = uart_register_driver(&serial_m3110_reg);
903 ret = spi_register_driver(&uart_max3110_driver);
905 uart_unregister_driver(&serial_m3110_reg);
910 static void __exit serial_m3110_exit(void)
912 spi_unregister_driver(&uart_max3110_driver);
913 uart_unregister_driver(&serial_m3110_reg);
916 module_init(serial_m3110_init);
917 module_exit(serial_m3110_exit);
919 MODULE_LICENSE("GPL v2");
920 MODULE_ALIAS("max3110-uart");