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 interrupt 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;
64 struct mutex io_mutex;
69 u8 parity, word_7bits;
72 unsigned long uart_flags;
75 struct circ_buf con_xmit;
78 /* global data structure, may need be removed */
79 static struct uart_max3110 *pmax;
81 static int receive_chars(struct uart_max3110 *max,
82 unsigned short *str, int len);
83 static int max3110_read_multi(struct uart_max3110 *max);
84 static void max3110_con_receive(struct uart_max3110 *max);
86 static int max3110_write_then_read(struct uart_max3110 *max,
87 const void *txbuf, void *rxbuf, unsigned len, int always_fast)
89 struct spi_device *spi = max->spi;
90 struct spi_message message;
91 struct spi_transfer x;
94 mutex_lock(&max->io_mutex);
95 spi_message_init(&message);
96 memset(&x, 0, sizeof x);
100 spi_message_add_tail(&x, &message);
103 x.speed_hz = spi->max_speed_hz;
105 x.speed_hz = max->baud;
108 ret = spi_sync(spi, &message);
109 mutex_unlock(&max->io_mutex);
113 /* Write a 16b word to the device */
114 static int max3110_out(struct uart_max3110 *max, const u16 out)
120 buf = kzalloc(8, GFP_KERNEL | GFP_DMA);
127 ret = max3110_write_then_read(max, obuf, ibuf, 2, 1);
129 pr_warning(PR_FMT "%s(): get err msg %d when sending 0x%x\n",
134 receive_chars(max, ibuf, 1);
142 * This is usually used to read data from SPIC RX FIFO, which doesn't
143 * need any delay like flushing character out.
145 * Return how many valide bytes are read back
147 static int max3110_read_multi(struct uart_max3110 *max)
153 blen = M3110_RX_FIFO_DEPTH * sizeof(u16);
154 buf = kzalloc(blen * 2, GFP_KERNEL | GFP_DMA);
156 pr_warning(PR_FMT "%s(): fail to alloc dma buffer\n", __func__);
160 /* tx/rx always have the same length */
164 if (max3110_write_then_read(max, obuf, ibuf, blen, 1)) {
169 ret = receive_chars(max, ibuf, M3110_RX_FIFO_DEPTH);
175 static void serial_m3110_con_putchar(struct uart_port *port, int ch)
177 struct uart_max3110 *max =
178 container_of(port, struct uart_max3110, port);
179 struct circ_buf *xmit = &max->con_xmit;
181 if (uart_circ_chars_free(xmit)) {
182 xmit->buf[xmit->head] = (char)ch;
183 xmit->head = (xmit->head + 1) & (PAGE_SIZE - 1);
188 * Print a string to the serial port trying not to disturb
189 * any possible real use of the port...
191 * The console_lock must be held when we get here.
193 static void serial_m3110_con_write(struct console *co,
194 const char *s, unsigned int count)
199 uart_console_write(&pmax->port, s, count, serial_m3110_con_putchar);
201 if (!test_and_set_bit(CON_TX_NEEDED, &pmax->uart_flags))
206 serial_m3110_con_setup(struct console *co, char *options)
208 struct uart_max3110 *max = pmax;
214 pr_info(PR_FMT "setting up console\n");
220 pr_err(PR_FMT "pmax is NULL, return");
225 uart_parse_options(options, &baud, &parity, &bits, &flow);
227 return uart_set_options(&max->port, co, baud, parity, bits, flow);
230 static struct tty_driver *serial_m3110_con_device(struct console *co,
233 struct uart_driver *p = co->data;
235 return p->tty_driver;
238 static struct uart_driver serial_m3110_reg;
239 static struct console serial_m3110_console = {
241 .write = serial_m3110_con_write,
242 .device = serial_m3110_con_device,
243 .setup = serial_m3110_con_setup,
244 .flags = CON_PRINTBUFFER,
246 .data = &serial_m3110_reg,
249 static unsigned int serial_m3110_tx_empty(struct uart_port *port)
254 static void serial_m3110_stop_tx(struct uart_port *port)
259 /* stop_rx will be called in spin_lock env */
260 static void serial_m3110_stop_rx(struct uart_port *port)
265 #define WORDS_PER_XFER 128
266 static void send_circ_buf(struct uart_max3110 *max,
267 struct circ_buf *xmit)
271 int i, len, blen, dma_size, left, ret = 0;
274 dma_size = WORDS_PER_XFER * sizeof(u16) * 2;
275 buf = kzalloc(dma_size, GFP_KERNEL | GFP_DMA);
279 ibuf = buf + dma_size/2;
281 while (!uart_circ_empty(xmit)) {
282 left = uart_circ_chars_pending(xmit);
284 len = min(left, WORDS_PER_XFER);
285 blen = len * sizeof(u16);
286 memset(ibuf, 0, blen);
288 for (i = 0; i < len; i++) {
289 obuf[i] = (u8)xmit->buf[xmit->tail] | WD_TAG;
290 xmit->tail = (xmit->tail + 1) &
291 (UART_XMIT_SIZE - 1);
294 /* Fail to send msg to console is not very critical */
296 ret = max3110_write_then_read(max, obuf, ibuf, blen, 0);
298 pr_warning(PR_FMT "%s(): get err msg %d\n",
301 receive_chars(max, ibuf, len);
303 max->port.icount.tx += len;
311 static void transmit_char(struct uart_max3110 *max)
313 struct uart_port *port = &max->port;
314 struct circ_buf *xmit = &port->state->xmit;
316 if (uart_circ_empty(xmit) || uart_tx_stopped(port))
319 send_circ_buf(max, xmit);
321 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
322 uart_write_wakeup(port);
324 if (uart_circ_empty(xmit))
325 serial_m3110_stop_tx(port);
329 * This will be called by uart_write() and tty_write, can't
332 static void serial_m3110_start_tx(struct uart_port *port)
334 struct uart_max3110 *max =
335 container_of(port, struct uart_max3110, port);
337 if (!test_and_set_bit(UART_TX_NEEDED, &max->uart_flags))
342 receive_chars(struct uart_max3110 *max, unsigned short *str, int len)
344 struct uart_port *port = &max->port;
345 struct tty_port *tport;
346 char buf[M3110_RX_FIFO_DEPTH];
349 /* If uart is not opened, just return */
353 tport = &port->state->port;
355 for (r = 0, w = 0; r < len; r++) {
356 if (str[r] & MAX3110_BREAK &&
357 uart_handle_break(port))
360 if (str[r] & MAX3110_READ_DATA_AVAILABLE) {
361 if (uart_handle_sysrq_char(port, str[r] & 0xff))
364 buf[w++] = str[r] & 0xff;
371 for (r = 0; w; r += usable, w -= usable) {
372 usable = tty_buffer_request_room(tport, w);
374 tty_insert_flip_string(tport, buf + r, usable);
375 port->icount.rx += usable;
378 tty_flip_buffer_push(tport);
384 * This routine will be used in read_thread or RX IRQ handling,
385 * it will first do one round buffer read(8 words), if there is some
386 * valid RX data, will try to read 5 more rounds till all data
389 * Use stack space as data buffer to save some system load, and chose
390 * 504 Btyes as a threadhold to do a bulk push to upper tty layer when
391 * receiving bulk data, a much bigger buffer may cause stack overflow
393 static void max3110_con_receive(struct uart_max3110 *max)
398 num = max3110_read_multi(max);
406 static int max3110_main_thread(void *_max)
408 struct uart_max3110 *max = _max;
409 wait_queue_head_t *wq = &max->wq;
411 struct circ_buf *xmit = &max->con_xmit;
413 pr_info(PR_FMT "start main thread\n");
416 wait_event_interruptible(*wq,
417 max->uart_flags || kthread_should_stop());
419 mutex_lock(&max->thread_mutex);
421 if (test_and_clear_bit(BIT_IRQ_PENDING, &max->uart_flags))
422 max3110_con_receive(max);
424 /* first handle console output */
425 if (test_and_clear_bit(CON_TX_NEEDED, &max->uart_flags))
426 send_circ_buf(max, xmit);
428 /* handle uart output */
429 if (test_and_clear_bit(UART_TX_NEEDED, &max->uart_flags))
432 mutex_unlock(&max->thread_mutex);
434 } while (!kthread_should_stop());
439 static irqreturn_t serial_m3110_irq(int irq, void *dev_id)
441 struct uart_max3110 *max = dev_id;
443 /* max3110's irq is a falling edge, not level triggered,
444 * so no need to disable the irq */
446 if (!test_and_set_bit(BIT_IRQ_PENDING, &max->uart_flags))
452 /* if don't use RX IRQ, then need a thread to polling read */
453 static int max3110_read_thread(void *_max)
455 struct uart_max3110 *max = _max;
457 pr_info(PR_FMT "start read thread\n");
460 * If can't acquire the mutex, it means the main thread
461 * is running which will also perform the rx job
463 if (mutex_trylock(&max->thread_mutex)) {
464 max3110_con_receive(max);
465 mutex_unlock(&max->thread_mutex);
468 set_current_state(TASK_INTERRUPTIBLE);
469 schedule_timeout(HZ / 20);
470 } while (!kthread_should_stop());
475 static int serial_m3110_startup(struct uart_port *port)
477 struct uart_max3110 *max =
478 container_of(port, struct uart_max3110, port);
482 if (port->line != 0) {
483 pr_err(PR_FMT "uart port startup failed\n");
487 /* Disable all IRQ and config it to 115200, 8n1 */
488 config = WC_TAG | WC_FIFO_ENABLE
493 /* as we use thread to handle tx/rx, need set low latency */
494 port->state->port.low_latency = 1;
497 max->read_thread = NULL;
498 ret = request_irq(max->irq, serial_m3110_irq,
499 IRQ_TYPE_EDGE_FALLING, "max3110", max);
502 pr_err(PR_FMT "unable to allocate IRQ, polling\n");
504 /* Enable RX IRQ only */
505 config |= WC_RXA_IRQ_ENABLE;
510 /* If IRQ is disabled, start a read thread for input data */
512 kthread_run(max3110_read_thread, max, "max3110_read");
513 if (IS_ERR(max->read_thread)) {
514 ret = PTR_ERR(max->read_thread);
515 max->read_thread = NULL;
516 pr_err(PR_FMT "Can't create read thread!\n");
521 ret = max3110_out(max, config);
524 free_irq(max->irq, max);
525 if (max->read_thread)
526 kthread_stop(max->read_thread);
527 max->read_thread = NULL;
531 max->cur_conf = config;
535 static void serial_m3110_shutdown(struct uart_port *port)
537 struct uart_max3110 *max =
538 container_of(port, struct uart_max3110, port);
541 if (max->read_thread) {
542 kthread_stop(max->read_thread);
543 max->read_thread = NULL;
547 free_irq(max->irq, max);
549 /* Disable interrupts from this port */
550 config = WC_TAG | WC_SW_SHDI;
551 max3110_out(max, config);
554 static void serial_m3110_release_port(struct uart_port *port)
558 static int serial_m3110_request_port(struct uart_port *port)
563 static void serial_m3110_config_port(struct uart_port *port, int flags)
565 port->type = PORT_MAX3100;
569 serial_m3110_verify_port(struct uart_port *port, struct serial_struct *ser)
571 /* we don't want the core code to modify any port params */
576 static const char *serial_m3110_type(struct uart_port *port)
578 struct uart_max3110 *max =
579 container_of(port, struct uart_max3110, port);
584 serial_m3110_set_termios(struct uart_port *port, struct ktermios *termios,
585 struct ktermios *old)
587 struct uart_max3110 *max =
588 container_of(port, struct uart_max3110, port);
590 unsigned int baud, parity = 0;
592 u16 new_conf = max->cur_conf;
594 switch (termios->c_cflag & CSIZE) {
596 cval = UART_LCR_WLEN7;
597 new_conf |= WC_7BIT_WORD;
600 /* We only support CS7 & CS8 */
601 termios->c_cflag &= ~CSIZE;
602 termios->c_cflag |= CS8;
604 cval = UART_LCR_WLEN8;
605 new_conf |= WC_8BIT_WORD;
609 baud = uart_get_baud_rate(port, termios, old, 0, 230400);
611 /* First calc the div for 1.8MHZ clock case */
614 clk_div = WC_BAUD_DR384;
617 clk_div = WC_BAUD_DR192;
620 clk_div = WC_BAUD_DR96;
623 clk_div = WC_BAUD_DR48;
626 clk_div = WC_BAUD_DR24;
629 clk_div = WC_BAUD_DR12;
632 clk_div = WC_BAUD_DR6;
635 clk_div = WC_BAUD_DR3;
638 clk_div = WC_BAUD_DR2;
641 clk_div = WC_BAUD_DR1;
644 if (max->clock & MAX3110_HIGH_CLK)
647 /* Pick the previous baud rate */
649 clk_div = max->cur_conf & WC_BAUD_DIV_MASK;
650 tty_termios_encode_baud_rate(termios, baud, baud);
653 if (max->clock & MAX3110_HIGH_CLK) {
655 /* High clk version max3110 doesn't support B300 */
658 clk_div = WC_BAUD_DR384;
661 clk_div = WC_BAUD_DR1;
662 tty_termios_encode_baud_rate(termios, baud, baud);
665 new_conf = (new_conf & ~WC_BAUD_DIV_MASK) | clk_div;
667 if (unlikely(termios->c_cflag & CMSPAR))
668 termios->c_cflag &= ~CMSPAR;
670 if (termios->c_cflag & CSTOPB)
671 new_conf |= WC_2_STOPBITS;
673 new_conf &= ~WC_2_STOPBITS;
675 if (termios->c_cflag & PARENB) {
676 new_conf |= WC_PARITY_ENABLE;
677 parity |= UART_LCR_PARITY;
679 new_conf &= ~WC_PARITY_ENABLE;
681 if (!(termios->c_cflag & PARODD))
682 parity |= UART_LCR_EPAR;
683 max->parity = parity;
685 uart_update_timeout(port, termios->c_cflag, baud);
688 if (new_conf != max->cur_conf) {
689 if (!max3110_out(max, new_conf)) {
690 max->cur_conf = new_conf;
696 /* Don't handle hw handshaking */
697 static unsigned int serial_m3110_get_mctrl(struct uart_port *port)
699 return TIOCM_DSR | TIOCM_CAR | TIOCM_DSR;
702 static void serial_m3110_set_mctrl(struct uart_port *port, unsigned int mctrl)
706 static void serial_m3110_break_ctl(struct uart_port *port, int break_state)
710 static void serial_m3110_pm(struct uart_port *port, unsigned int state,
711 unsigned int oldstate)
715 static void serial_m3110_enable_ms(struct uart_port *port)
719 static struct uart_ops serial_m3110_ops = {
720 .tx_empty = serial_m3110_tx_empty,
721 .set_mctrl = serial_m3110_set_mctrl,
722 .get_mctrl = serial_m3110_get_mctrl,
723 .stop_tx = serial_m3110_stop_tx,
724 .start_tx = serial_m3110_start_tx,
725 .stop_rx = serial_m3110_stop_rx,
726 .enable_ms = serial_m3110_enable_ms,
727 .break_ctl = serial_m3110_break_ctl,
728 .startup = serial_m3110_startup,
729 .shutdown = serial_m3110_shutdown,
730 .set_termios = serial_m3110_set_termios,
731 .pm = serial_m3110_pm,
732 .type = serial_m3110_type,
733 .release_port = serial_m3110_release_port,
734 .request_port = serial_m3110_request_port,
735 .config_port = serial_m3110_config_port,
736 .verify_port = serial_m3110_verify_port,
739 static struct uart_driver serial_m3110_reg = {
740 .owner = THIS_MODULE,
741 .driver_name = "MRST serial",
746 .cons = &serial_m3110_console,
749 #ifdef CONFIG_PM_SLEEP
750 static int serial_m3110_suspend(struct device *dev)
752 struct spi_device *spi = to_spi_device(dev);
753 struct uart_max3110 *max = spi_get_drvdata(spi);
756 disable_irq(max->irq);
757 uart_suspend_port(&serial_m3110_reg, &max->port);
758 max3110_out(max, max->cur_conf | WC_SW_SHDI);
762 static int serial_m3110_resume(struct device *dev)
764 struct spi_device *spi = to_spi_device(dev);
765 struct uart_max3110 *max = spi_get_drvdata(spi);
767 max3110_out(max, max->cur_conf);
768 uart_resume_port(&serial_m3110_reg, &max->port);
770 enable_irq(max->irq);
774 static SIMPLE_DEV_PM_OPS(serial_m3110_pm_ops, serial_m3110_suspend,
775 serial_m3110_resume);
776 #define SERIAL_M3110_PM_OPS (&serial_m3110_pm_ops)
779 #define SERIAL_M3110_PM_OPS NULL
782 static int serial_m3110_probe(struct spi_device *spi)
784 struct uart_max3110 *max;
789 max = kzalloc(sizeof(*max), GFP_KERNEL);
794 spi->bits_per_word = 16;
795 max->clock = MAX3110_HIGH_CLK;
799 max->port.type = PORT_MAX3100;
800 max->port.fifosize = 2; /* Only have 16b buffer */
801 max->port.ops = &serial_m3110_ops;
803 max->port.dev = &spi->dev;
804 max->port.uartclk = 115200;
807 strcpy(max->name, spi->modalias);
808 max->irq = (u16)spi->irq;
810 mutex_init(&max->thread_mutex);
811 mutex_init(&max->io_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 = (unsigned char __iomem *)0xff110000;
854 uart_add_one_port(&serial_m3110_reg, &max->port);
859 free_page((unsigned long)buffer);
865 static int 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 .owner = THIS_MODULE,
887 .pm = SERIAL_M3110_PM_OPS,
889 .probe = serial_m3110_probe,
890 .remove = serial_m3110_remove,
893 static int __init serial_m3110_init(void)
897 ret = uart_register_driver(&serial_m3110_reg);
901 ret = spi_register_driver(&uart_max3110_driver);
903 uart_unregister_driver(&serial_m3110_reg);
908 static void __exit serial_m3110_exit(void)
910 spi_unregister_driver(&uart_max3110_driver);
911 uart_unregister_driver(&serial_m3110_reg);
914 module_init(serial_m3110_init);
915 module_exit(serial_m3110_exit);
917 MODULE_LICENSE("GPL v2");
918 MODULE_ALIAS("spi:max3110-uart");