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 #ifdef CONFIG_MAGIC_SYSRQ
34 #include <linux/module.h>
35 #include <linux/ioport.h>
36 #include <linux/irq.h>
37 #include <linux/init.h>
38 #include <linux/console.h>
39 #include <linux/tty.h>
40 #include <linux/tty_flip.h>
41 #include <linux/serial_core.h>
42 #include <linux/serial_reg.h>
44 #include <linux/kthread.h>
45 #include <linux/spi/spi.h>
47 #include "mrst_max3110.h"
49 #define PR_FMT "mrst_max3110: "
51 #define UART_TX_NEEDED 1
52 #define CON_TX_NEEDED 2
53 #define BIT_IRQ_PENDING 3
56 struct uart_port port;
57 struct spi_device *spi;
58 char name[SPI_NAME_SIZE];
61 struct task_struct *main_thread;
62 struct task_struct *read_thread;
63 struct mutex thread_mutex;
68 u8 parity, word_7bits;
71 unsigned long uart_flags;
74 struct circ_buf con_xmit;
77 /* global data structure, may need be removed */
78 static struct uart_max3110 *pmax;
80 static int receive_chars(struct uart_max3110 *max,
81 unsigned short *str, int len);
82 static int max3110_read_multi(struct uart_max3110 *max);
83 static void max3110_con_receive(struct uart_max3110 *max);
85 static int max3110_write_then_read(struct uart_max3110 *max,
86 const void *txbuf, void *rxbuf, unsigned len, int always_fast)
88 struct spi_device *spi = max->spi;
89 struct spi_message message;
90 struct spi_transfer x;
93 spi_message_init(&message);
94 memset(&x, 0, sizeof x);
98 spi_message_add_tail(&x, &message);
101 x.speed_hz = spi->max_speed_hz;
103 x.speed_hz = max->baud;
106 ret = spi_sync(spi, &message);
110 /* Write a 16b word to the device */
111 static int max3110_out(struct uart_max3110 *max, const u16 out)
117 buf = kzalloc(8, GFP_KERNEL | GFP_DMA);
124 ret = max3110_write_then_read(max, obuf, ibuf, 2, 1);
126 pr_warning(PR_FMT "%s(): get err msg %d when sending 0x%x\n",
131 receive_chars(max, ibuf, 1);
139 * This is usually used to read data from SPIC RX FIFO, which doesn't
140 * need any delay like flushing character out.
142 * Return how many valide bytes are read back
144 static int max3110_read_multi(struct uart_max3110 *max)
150 blen = M3110_RX_FIFO_DEPTH * sizeof(u16);
151 buf = kzalloc(blen * 2, GFP_KERNEL | GFP_DMA);
153 pr_warning(PR_FMT "%s(): fail to alloc dma buffer\n", __func__);
157 /* tx/rx always have the same length */
161 if (max3110_write_then_read(max, obuf, ibuf, blen, 1)) {
166 ret = receive_chars(max, ibuf, M3110_RX_FIFO_DEPTH);
172 static void serial_m3110_con_putchar(struct uart_port *port, int ch)
174 struct uart_max3110 *max =
175 container_of(port, struct uart_max3110, port);
176 struct circ_buf *xmit = &max->con_xmit;
178 if (uart_circ_chars_free(xmit)) {
179 xmit->buf[xmit->head] = (char)ch;
180 xmit->head = (xmit->head + 1) & (PAGE_SIZE - 1);
185 * Print a string to the serial port trying not to disturb
186 * any possible real use of the port...
188 * The console_lock must be held when we get here.
190 static void serial_m3110_con_write(struct console *co,
191 const char *s, unsigned int count)
196 uart_console_write(&pmax->port, s, count, serial_m3110_con_putchar);
198 if (!test_and_set_bit(CON_TX_NEEDED, &pmax->uart_flags))
203 serial_m3110_con_setup(struct console *co, char *options)
205 struct uart_max3110 *max = pmax;
211 pr_info(PR_FMT "setting up console\n");
217 pr_err(PR_FMT "pmax is NULL, return");
222 uart_parse_options(options, &baud, &parity, &bits, &flow);
224 return uart_set_options(&max->port, co, baud, parity, bits, flow);
227 static struct tty_driver *serial_m3110_con_device(struct console *co,
230 struct uart_driver *p = co->data;
232 return p->tty_driver;
235 static struct uart_driver serial_m3110_reg;
236 static struct console serial_m3110_console = {
238 .write = serial_m3110_con_write,
239 .device = serial_m3110_con_device,
240 .setup = serial_m3110_con_setup,
241 .flags = CON_PRINTBUFFER,
243 .data = &serial_m3110_reg,
246 static unsigned int serial_m3110_tx_empty(struct uart_port *port)
251 static void serial_m3110_stop_tx(struct uart_port *port)
256 /* stop_rx will be called in spin_lock env */
257 static void serial_m3110_stop_rx(struct uart_port *port)
262 #define WORDS_PER_XFER 128
263 static void send_circ_buf(struct uart_max3110 *max,
264 struct circ_buf *xmit)
268 int i, len, blen, dma_size, left, ret = 0;
271 dma_size = WORDS_PER_XFER * sizeof(u16) * 2;
272 buf = kzalloc(dma_size, GFP_KERNEL | GFP_DMA);
276 ibuf = buf + dma_size/2;
278 while (!uart_circ_empty(xmit)) {
279 left = uart_circ_chars_pending(xmit);
281 len = min(left, WORDS_PER_XFER);
282 blen = len * sizeof(u16);
283 memset(ibuf, 0, blen);
285 for (i = 0; i < len; i++) {
286 obuf[i] = (u8)xmit->buf[xmit->tail] | WD_TAG;
287 xmit->tail = (xmit->tail + 1) &
288 (UART_XMIT_SIZE - 1);
291 /* Fail to send msg to console is not very critical */
293 ret = max3110_write_then_read(max, obuf, ibuf, blen, 0);
295 pr_warning(PR_FMT "%s(): get err msg %d\n",
298 receive_chars(max, ibuf, len);
300 max->port.icount.tx += len;
308 static void transmit_char(struct uart_max3110 *max)
310 struct uart_port *port = &max->port;
311 struct circ_buf *xmit = &port->state->xmit;
313 if (uart_circ_empty(xmit) || uart_tx_stopped(port))
316 send_circ_buf(max, xmit);
318 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
319 uart_write_wakeup(port);
321 if (uart_circ_empty(xmit))
322 serial_m3110_stop_tx(port);
326 * This will be called by uart_write() and tty_write, can't
329 static void serial_m3110_start_tx(struct uart_port *port)
331 struct uart_max3110 *max =
332 container_of(port, struct uart_max3110, port);
334 if (!test_and_set_bit(UART_TX_NEEDED, &max->uart_flags))
339 receive_chars(struct uart_max3110 *max, unsigned short *str, int len)
341 struct uart_port *port = &max->port;
342 struct tty_struct *tty;
343 char buf[M3110_RX_FIFO_DEPTH];
346 /* If uart is not opened, just return */
350 tty = port->state->port.tty;
354 for (r = 0, w = 0; r < len; r++) {
355 if (str[r] & MAX3110_BREAK &&
356 uart_handle_break(port))
359 if (str[r] & MAX3110_READ_DATA_AVAILABLE) {
360 if (uart_handle_sysrq_char(port, str[r] & 0xff))
363 buf[w++] = str[r] & 0xff;
370 for (r = 0; w; r += usable, w -= usable) {
371 usable = tty_buffer_request_room(tty, w);
373 tty_insert_flip_string(tty, buf + r, usable);
374 port->icount.rx += usable;
377 tty_flip_buffer_push(tty);
383 * This routine will be used in read_thread or RX IRQ handling,
384 * it will first do one round buffer read(8 words), if there is some
385 * valid RX data, will try to read 5 more rounds till all data
388 * Use stack space as data buffer to save some system load, and chose
389 * 504 Btyes as a threadhold to do a bulk push to upper tty layer when
390 * receiving bulk data, a much bigger buffer may cause stack overflow
392 static void max3110_con_receive(struct uart_max3110 *max)
397 num = max3110_read_multi(max);
405 static int max3110_main_thread(void *_max)
407 struct uart_max3110 *max = _max;
408 wait_queue_head_t *wq = &max->wq;
410 struct circ_buf *xmit = &max->con_xmit;
412 pr_info(PR_FMT "start main thread\n");
415 wait_event_interruptible(*wq,
416 max->uart_flags || kthread_should_stop());
418 mutex_lock(&max->thread_mutex);
420 if (test_and_clear_bit(BIT_IRQ_PENDING, &max->uart_flags))
421 max3110_con_receive(max);
423 /* first handle console output */
424 if (test_and_clear_bit(CON_TX_NEEDED, &max->uart_flags))
425 send_circ_buf(max, xmit);
427 /* handle uart output */
428 if (test_and_clear_bit(UART_TX_NEEDED, &max->uart_flags))
431 mutex_unlock(&max->thread_mutex);
433 } while (!kthread_should_stop());
438 static irqreturn_t serial_m3110_irq(int irq, void *dev_id)
440 struct uart_max3110 *max = dev_id;
442 /* max3110's irq is a falling edge, not level triggered,
443 * so no need to disable the irq */
445 if (!test_and_set_bit(BIT_IRQ_PENDING, &max->uart_flags))
451 /* if don't use RX IRQ, then need a thread to polling read */
452 static int max3110_read_thread(void *_max)
454 struct uart_max3110 *max = _max;
456 pr_info(PR_FMT "start read thread\n");
459 * If can't acquire the mutex, it means the main thread
460 * is running which will also perform the rx job
462 if (mutex_trylock(&max->thread_mutex)) {
463 max3110_con_receive(max);
464 mutex_unlock(&max->thread_mutex);
467 set_current_state(TASK_INTERRUPTIBLE);
468 schedule_timeout(HZ / 20);
469 } while (!kthread_should_stop());
474 static int serial_m3110_startup(struct uart_port *port)
476 struct uart_max3110 *max =
477 container_of(port, struct uart_max3110, port);
481 if (port->line != 0) {
482 pr_err(PR_FMT "uart port startup failed\n");
486 /* Disable all IRQ and config it to 115200, 8n1 */
487 config = WC_TAG | WC_FIFO_ENABLE
492 /* as we use thread to handle tx/rx, need set low latency */
493 port->state->port.tty->low_latency = 1;
496 max->read_thread = NULL;
497 ret = request_irq(max->irq, serial_m3110_irq,
498 IRQ_TYPE_EDGE_FALLING, "max3110", max);
501 pr_err(PR_FMT "unable to allocate IRQ, polling\n");
503 /* Enable RX IRQ only */
504 config |= WC_RXA_IRQ_ENABLE;
509 /* If IRQ is disabled, start a read thread for input data */
511 kthread_run(max3110_read_thread, max, "max3110_read");
512 if (IS_ERR(max->read_thread)) {
513 ret = PTR_ERR(max->read_thread);
514 max->read_thread = NULL;
515 pr_err(PR_FMT "Can't create read thread!\n");
520 ret = max3110_out(max, config);
523 free_irq(max->irq, max);
524 if (max->read_thread)
525 kthread_stop(max->read_thread);
526 max->read_thread = NULL;
530 max->cur_conf = config;
534 static void serial_m3110_shutdown(struct uart_port *port)
536 struct uart_max3110 *max =
537 container_of(port, struct uart_max3110, port);
540 if (max->read_thread) {
541 kthread_stop(max->read_thread);
542 max->read_thread = NULL;
546 free_irq(max->irq, max);
548 /* Disable interrupts from this port */
549 config = WC_TAG | WC_SW_SHDI;
550 max3110_out(max, config);
553 static void serial_m3110_release_port(struct uart_port *port)
557 static int serial_m3110_request_port(struct uart_port *port)
562 static void serial_m3110_config_port(struct uart_port *port, int flags)
564 port->type = PORT_MAX3100;
568 serial_m3110_verify_port(struct uart_port *port, struct serial_struct *ser)
570 /* we don't want the core code to modify any port params */
575 static const char *serial_m3110_type(struct uart_port *port)
577 struct uart_max3110 *max =
578 container_of(port, struct uart_max3110, port);
583 serial_m3110_set_termios(struct uart_port *port, struct ktermios *termios,
584 struct ktermios *old)
586 struct uart_max3110 *max =
587 container_of(port, struct uart_max3110, port);
589 unsigned int baud, parity = 0;
591 u16 new_conf = max->cur_conf;
593 switch (termios->c_cflag & CSIZE) {
595 cval = UART_LCR_WLEN7;
596 new_conf |= WC_7BIT_WORD;
599 /* We only support CS7 & CS8 */
600 termios->c_cflag &= ~CSIZE;
601 termios->c_cflag |= CS8;
603 cval = UART_LCR_WLEN8;
604 new_conf |= WC_8BIT_WORD;
608 baud = uart_get_baud_rate(port, termios, old, 0, 230400);
610 /* First calc the div for 1.8MHZ clock case */
613 clk_div = WC_BAUD_DR384;
616 clk_div = WC_BAUD_DR192;
619 clk_div = WC_BAUD_DR96;
622 clk_div = WC_BAUD_DR48;
625 clk_div = WC_BAUD_DR24;
628 clk_div = WC_BAUD_DR12;
631 clk_div = WC_BAUD_DR6;
634 clk_div = WC_BAUD_DR3;
637 clk_div = WC_BAUD_DR2;
640 clk_div = WC_BAUD_DR1;
643 if (max->clock & MAX3110_HIGH_CLK)
646 /* Pick the previous baud rate */
648 clk_div = max->cur_conf & WC_BAUD_DIV_MASK;
649 tty_termios_encode_baud_rate(termios, baud, baud);
652 if (max->clock & MAX3110_HIGH_CLK) {
654 /* High clk version max3110 doesn't support B300 */
657 clk_div = WC_BAUD_DR384;
660 clk_div = WC_BAUD_DR1;
661 tty_termios_encode_baud_rate(termios, baud, baud);
664 new_conf = (new_conf & ~WC_BAUD_DIV_MASK) | clk_div;
666 if (unlikely(termios->c_cflag & CMSPAR))
667 termios->c_cflag &= ~CMSPAR;
669 if (termios->c_cflag & CSTOPB)
670 new_conf |= WC_2_STOPBITS;
672 new_conf &= ~WC_2_STOPBITS;
674 if (termios->c_cflag & PARENB) {
675 new_conf |= WC_PARITY_ENABLE;
676 parity |= UART_LCR_PARITY;
678 new_conf &= ~WC_PARITY_ENABLE;
680 if (!(termios->c_cflag & PARODD))
681 parity |= UART_LCR_EPAR;
682 max->parity = parity;
684 uart_update_timeout(port, termios->c_cflag, baud);
687 if (new_conf != max->cur_conf) {
688 if (!max3110_out(max, new_conf)) {
689 max->cur_conf = new_conf;
695 /* Don't handle hw handshaking */
696 static unsigned int serial_m3110_get_mctrl(struct uart_port *port)
698 return TIOCM_DSR | TIOCM_CAR | TIOCM_DSR;
701 static void serial_m3110_set_mctrl(struct uart_port *port, unsigned int mctrl)
705 static void serial_m3110_break_ctl(struct uart_port *port, int break_state)
709 static void serial_m3110_pm(struct uart_port *port, unsigned int state,
710 unsigned int oldstate)
714 static void serial_m3110_enable_ms(struct uart_port *port)
718 struct uart_ops serial_m3110_ops = {
719 .tx_empty = serial_m3110_tx_empty,
720 .set_mctrl = serial_m3110_set_mctrl,
721 .get_mctrl = serial_m3110_get_mctrl,
722 .stop_tx = serial_m3110_stop_tx,
723 .start_tx = serial_m3110_start_tx,
724 .stop_rx = serial_m3110_stop_rx,
725 .enable_ms = serial_m3110_enable_ms,
726 .break_ctl = serial_m3110_break_ctl,
727 .startup = serial_m3110_startup,
728 .shutdown = serial_m3110_shutdown,
729 .set_termios = serial_m3110_set_termios,
730 .pm = serial_m3110_pm,
731 .type = serial_m3110_type,
732 .release_port = serial_m3110_release_port,
733 .request_port = serial_m3110_request_port,
734 .config_port = serial_m3110_config_port,
735 .verify_port = serial_m3110_verify_port,
738 static struct uart_driver serial_m3110_reg = {
739 .owner = THIS_MODULE,
740 .driver_name = "MRST serial",
745 .cons = &serial_m3110_console,
749 static int serial_m3110_suspend(struct spi_device *spi, pm_message_t state)
751 struct uart_max3110 *max = spi_get_drvdata(spi);
753 disable_irq(max->irq);
754 uart_suspend_port(&serial_m3110_reg, &max->port);
755 max3110_out(max, max->cur_conf | WC_SW_SHDI);
759 static int serial_m3110_resume(struct spi_device *spi)
761 struct uart_max3110 *max = spi_get_drvdata(spi);
763 max3110_out(max, max->cur_conf);
764 uart_resume_port(&serial_m3110_reg, &max->port);
765 enable_irq(max->irq);
769 #define serial_m3110_suspend NULL
770 #define serial_m3110_resume NULL
773 static int __devinit serial_m3110_probe(struct spi_device *spi)
775 struct uart_max3110 *max;
780 max = kzalloc(sizeof(*max), GFP_KERNEL);
785 spi->bits_per_word = 16;
786 max->clock = MAX3110_HIGH_CLK;
790 max->port.type = PORT_MAX3100;
791 max->port.fifosize = 2; /* Only have 16b buffer */
792 max->port.ops = &serial_m3110_ops;
794 max->port.dev = &spi->dev;
795 max->port.uartclk = 115200;
798 strcpy(max->name, spi->modalias);
799 max->irq = (u16)spi->irq;
801 mutex_init(&max->thread_mutex);
810 /* Check if reading configuration register returns something sane */
813 ret = max3110_write_then_read(max, (u8 *)&res, (u8 *)&res, 2, 0);
814 if (ret < 0 || res == 0 || res == 0xffff) {
815 dev_dbg(&spi->dev, "MAX3111 deemed not present (conf reg %04x)",
821 buffer = (void *)__get_free_page(GFP_KERNEL);
826 max->con_xmit.buf = buffer;
827 max->con_xmit.head = 0;
828 max->con_xmit.tail = 0;
830 init_waitqueue_head(&max->wq);
832 max->main_thread = kthread_run(max3110_main_thread,
833 max, "max3110_main");
834 if (IS_ERR(max->main_thread)) {
835 ret = PTR_ERR(max->main_thread);
839 spi_set_drvdata(spi, max);
842 /* Give membase a psudo value to pass serial_core's check */
843 max->port.membase = (void *)0xff110000;
844 uart_add_one_port(&serial_m3110_reg, &max->port);
849 free_page((unsigned long)buffer);
855 static int __devexit serial_m3110_remove(struct spi_device *dev)
857 struct uart_max3110 *max = spi_get_drvdata(dev);
862 uart_remove_one_port(&serial_m3110_reg, &max->port);
864 free_page((unsigned long)max->con_xmit.buf);
866 if (max->main_thread)
867 kthread_stop(max->main_thread);
873 static struct spi_driver uart_max3110_driver = {
875 .name = "spi_max3111",
876 .bus = &spi_bus_type,
877 .owner = THIS_MODULE,
879 .probe = serial_m3110_probe,
880 .remove = __devexit_p(serial_m3110_remove),
881 .suspend = serial_m3110_suspend,
882 .resume = serial_m3110_resume,
885 static int __init serial_m3110_init(void)
889 ret = uart_register_driver(&serial_m3110_reg);
893 ret = spi_register_driver(&uart_max3110_driver);
895 uart_unregister_driver(&serial_m3110_reg);
900 static void __exit serial_m3110_exit(void)
902 spi_unregister_driver(&uart_max3110_driver);
903 uart_unregister_driver(&serial_m3110_reg);
906 module_init(serial_m3110_init);
907 module_exit(serial_m3110_exit);
909 MODULE_LICENSE("GPL v2");
910 MODULE_ALIAS("max3110-uart");