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>
48 #include "mrst_max3110.h"
50 #define PR_FMT "mrst_max3110: "
52 #define UART_TX_NEEDED 1
53 #define CON_TX_NEEDED 2
54 #define BIT_IRQ_PENDING 3
57 struct uart_port port;
58 struct spi_device *spi;
59 char name[SPI_NAME_SIZE];
62 struct task_struct *main_thread;
63 struct task_struct *read_thread;
64 struct mutex thread_mutex;
65 struct mutex io_mutex;
70 u8 parity, word_7bits;
73 unsigned long uart_flags;
76 struct circ_buf con_xmit;
79 /* global data structure, may need be removed */
80 static struct uart_max3110 *pmax;
82 static int receive_chars(struct uart_max3110 *max,
83 unsigned short *str, int len);
84 static int max3110_read_multi(struct uart_max3110 *max);
85 static void max3110_con_receive(struct uart_max3110 *max);
87 static int max3110_write_then_read(struct uart_max3110 *max,
88 const void *txbuf, void *rxbuf, unsigned len, int always_fast)
90 struct spi_device *spi = max->spi;
91 struct spi_message message;
92 struct spi_transfer x;
95 mutex_lock(&max->io_mutex);
96 spi_message_init(&message);
97 memset(&x, 0, sizeof x);
101 spi_message_add_tail(&x, &message);
104 x.speed_hz = spi->max_speed_hz;
106 x.speed_hz = max->baud;
109 ret = spi_sync(spi, &message);
110 mutex_unlock(&max->io_mutex);
114 /* Write a 16b word to the device */
115 static int max3110_out(struct uart_max3110 *max, const u16 out)
121 buf = kzalloc(8, GFP_KERNEL | GFP_DMA);
128 ret = max3110_write_then_read(max, obuf, ibuf, 2, 1);
130 pr_warning(PR_FMT "%s(): get err msg %d when sending 0x%x\n",
135 receive_chars(max, ibuf, 1);
143 * This is usually used to read data from SPIC RX FIFO, which doesn't
144 * need any delay like flushing character out.
146 * Return how many valide bytes are read back
148 static int max3110_read_multi(struct uart_max3110 *max)
154 blen = M3110_RX_FIFO_DEPTH * sizeof(u16);
155 buf = kzalloc(blen * 2, GFP_KERNEL | GFP_DMA);
157 pr_warning(PR_FMT "%s(): fail to alloc dma buffer\n", __func__);
161 /* tx/rx always have the same length */
165 if (max3110_write_then_read(max, obuf, ibuf, blen, 1)) {
170 ret = receive_chars(max, ibuf, M3110_RX_FIFO_DEPTH);
176 static void serial_m3110_con_putchar(struct uart_port *port, int ch)
178 struct uart_max3110 *max =
179 container_of(port, struct uart_max3110, port);
180 struct circ_buf *xmit = &max->con_xmit;
182 if (uart_circ_chars_free(xmit)) {
183 xmit->buf[xmit->head] = (char)ch;
184 xmit->head = (xmit->head + 1) & (PAGE_SIZE - 1);
189 * Print a string to the serial port trying not to disturb
190 * any possible real use of the port...
192 * The console_lock must be held when we get here.
194 static void serial_m3110_con_write(struct console *co,
195 const char *s, unsigned int count)
200 uart_console_write(&pmax->port, s, count, serial_m3110_con_putchar);
202 if (!test_and_set_bit(CON_TX_NEEDED, &pmax->uart_flags))
207 serial_m3110_con_setup(struct console *co, char *options)
209 struct uart_max3110 *max = pmax;
215 pr_info(PR_FMT "setting up console\n");
221 pr_err(PR_FMT "pmax is NULL, return");
226 uart_parse_options(options, &baud, &parity, &bits, &flow);
228 return uart_set_options(&max->port, co, baud, parity, bits, flow);
231 static struct tty_driver *serial_m3110_con_device(struct console *co,
234 struct uart_driver *p = co->data;
236 return p->tty_driver;
239 static struct uart_driver serial_m3110_reg;
240 static struct console serial_m3110_console = {
242 .write = serial_m3110_con_write,
243 .device = serial_m3110_con_device,
244 .setup = serial_m3110_con_setup,
245 .flags = CON_PRINTBUFFER,
247 .data = &serial_m3110_reg,
250 static unsigned int serial_m3110_tx_empty(struct uart_port *port)
255 static void serial_m3110_stop_tx(struct uart_port *port)
260 /* stop_rx will be called in spin_lock env */
261 static void serial_m3110_stop_rx(struct uart_port *port)
266 #define WORDS_PER_XFER 128
267 static void send_circ_buf(struct uart_max3110 *max,
268 struct circ_buf *xmit)
272 int i, len, blen, dma_size, left, ret = 0;
275 dma_size = WORDS_PER_XFER * sizeof(u16) * 2;
276 buf = kzalloc(dma_size, GFP_KERNEL | GFP_DMA);
280 ibuf = buf + dma_size/2;
282 while (!uart_circ_empty(xmit)) {
283 left = uart_circ_chars_pending(xmit);
285 len = min(left, WORDS_PER_XFER);
286 blen = len * sizeof(u16);
287 memset(ibuf, 0, blen);
289 for (i = 0; i < len; i++) {
290 obuf[i] = (u8)xmit->buf[xmit->tail] | WD_TAG;
291 xmit->tail = (xmit->tail + 1) &
292 (UART_XMIT_SIZE - 1);
295 /* Fail to send msg to console is not very critical */
297 ret = max3110_write_then_read(max, obuf, ibuf, blen, 0);
299 pr_warning(PR_FMT "%s(): get err msg %d\n",
302 receive_chars(max, ibuf, len);
304 max->port.icount.tx += len;
312 static void transmit_char(struct uart_max3110 *max)
314 struct uart_port *port = &max->port;
315 struct circ_buf *xmit = &port->state->xmit;
317 if (uart_circ_empty(xmit) || uart_tx_stopped(port))
320 send_circ_buf(max, xmit);
322 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
323 uart_write_wakeup(port);
325 if (uart_circ_empty(xmit))
326 serial_m3110_stop_tx(port);
330 * This will be called by uart_write() and tty_write, can't
333 static void serial_m3110_start_tx(struct uart_port *port)
335 struct uart_max3110 *max =
336 container_of(port, struct uart_max3110, port);
338 if (!test_and_set_bit(UART_TX_NEEDED, &max->uart_flags))
343 receive_chars(struct uart_max3110 *max, unsigned short *str, int len)
345 struct uart_port *port = &max->port;
346 struct tty_port *tport;
347 char buf[M3110_RX_FIFO_DEPTH];
350 /* If uart is not opened, just return */
354 tport = &port->state->port;
356 for (r = 0, w = 0; r < len; r++) {
357 if (str[r] & MAX3110_BREAK &&
358 uart_handle_break(port))
361 if (str[r] & MAX3110_READ_DATA_AVAILABLE) {
362 if (uart_handle_sysrq_char(port, str[r] & 0xff))
365 buf[w++] = str[r] & 0xff;
372 for (r = 0; w; r += usable, w -= usable) {
373 usable = tty_buffer_request_room(tport, w);
375 tty_insert_flip_string(tport, buf + r, usable);
376 port->icount.rx += usable;
379 tty_flip_buffer_push(tport);
385 * This routine will be used in read_thread or RX IRQ handling,
386 * it will first do one round buffer read(8 words), if there is some
387 * valid RX data, will try to read 5 more rounds till all data
390 * Use stack space as data buffer to save some system load, and chose
391 * 504 Btyes as a threadhold to do a bulk push to upper tty layer when
392 * receiving bulk data, a much bigger buffer may cause stack overflow
394 static void max3110_con_receive(struct uart_max3110 *max)
399 num = max3110_read_multi(max);
407 static int max3110_main_thread(void *_max)
409 struct uart_max3110 *max = _max;
410 wait_queue_head_t *wq = &max->wq;
412 struct circ_buf *xmit = &max->con_xmit;
414 pr_info(PR_FMT "start main thread\n");
417 wait_event_interruptible(*wq,
418 max->uart_flags || kthread_should_stop());
420 mutex_lock(&max->thread_mutex);
422 if (test_and_clear_bit(BIT_IRQ_PENDING, &max->uart_flags))
423 max3110_con_receive(max);
425 /* first handle console output */
426 if (test_and_clear_bit(CON_TX_NEEDED, &max->uart_flags))
427 send_circ_buf(max, xmit);
429 /* handle uart output */
430 if (test_and_clear_bit(UART_TX_NEEDED, &max->uart_flags))
433 mutex_unlock(&max->thread_mutex);
435 } while (!kthread_should_stop());
440 static irqreturn_t serial_m3110_irq(int irq, void *dev_id)
442 struct uart_max3110 *max = dev_id;
444 /* max3110's irq is a falling edge, not level triggered,
445 * so no need to disable the irq */
447 if (!test_and_set_bit(BIT_IRQ_PENDING, &max->uart_flags))
453 /* if don't use RX IRQ, then need a thread to polling read */
454 static int max3110_read_thread(void *_max)
456 struct uart_max3110 *max = _max;
458 pr_info(PR_FMT "start read thread\n");
461 * If can't acquire the mutex, it means the main thread
462 * is running which will also perform the rx job
464 if (mutex_trylock(&max->thread_mutex)) {
465 max3110_con_receive(max);
466 mutex_unlock(&max->thread_mutex);
469 set_current_state(TASK_INTERRUPTIBLE);
470 schedule_timeout(HZ / 20);
471 } while (!kthread_should_stop());
476 static int serial_m3110_startup(struct uart_port *port)
478 struct uart_max3110 *max =
479 container_of(port, struct uart_max3110, port);
483 if (port->line != 0) {
484 pr_err(PR_FMT "uart port startup failed\n");
488 /* Disable all IRQ and config it to 115200, 8n1 */
489 config = WC_TAG | WC_FIFO_ENABLE
494 /* as we use thread to handle tx/rx, need set low latency */
495 port->state->port.low_latency = 1;
498 /* Enable RX IRQ only */
499 config |= WC_RXA_IRQ_ENABLE;
501 /* If IRQ is disabled, start a read thread for input data */
503 kthread_run(max3110_read_thread, max, "max3110_read");
504 if (IS_ERR(max->read_thread)) {
505 ret = PTR_ERR(max->read_thread);
506 max->read_thread = NULL;
507 pr_err(PR_FMT "Can't create read thread!\n");
512 ret = max3110_out(max, config);
514 if (max->read_thread)
515 kthread_stop(max->read_thread);
516 max->read_thread = NULL;
520 max->cur_conf = config;
524 static void serial_m3110_shutdown(struct uart_port *port)
526 struct uart_max3110 *max =
527 container_of(port, struct uart_max3110, port);
530 if (max->read_thread) {
531 kthread_stop(max->read_thread);
532 max->read_thread = NULL;
535 /* Disable interrupts from this port */
536 config = WC_TAG | WC_SW_SHDI;
537 max3110_out(max, config);
540 static void serial_m3110_release_port(struct uart_port *port)
544 static int serial_m3110_request_port(struct uart_port *port)
549 static void serial_m3110_config_port(struct uart_port *port, int flags)
551 port->type = PORT_MAX3100;
555 serial_m3110_verify_port(struct uart_port *port, struct serial_struct *ser)
557 /* we don't want the core code to modify any port params */
562 static const char *serial_m3110_type(struct uart_port *port)
564 struct uart_max3110 *max =
565 container_of(port, struct uart_max3110, port);
570 serial_m3110_set_termios(struct uart_port *port, struct ktermios *termios,
571 struct ktermios *old)
573 struct uart_max3110 *max =
574 container_of(port, struct uart_max3110, port);
576 unsigned int baud, parity = 0;
578 u16 new_conf = max->cur_conf;
580 switch (termios->c_cflag & CSIZE) {
582 cval = UART_LCR_WLEN7;
583 new_conf |= WC_7BIT_WORD;
586 /* We only support CS7 & CS8 */
587 termios->c_cflag &= ~CSIZE;
588 termios->c_cflag |= CS8;
590 cval = UART_LCR_WLEN8;
591 new_conf |= WC_8BIT_WORD;
595 baud = uart_get_baud_rate(port, termios, old, 0, 230400);
597 /* First calc the div for 1.8MHZ clock case */
600 clk_div = WC_BAUD_DR384;
603 clk_div = WC_BAUD_DR192;
606 clk_div = WC_BAUD_DR96;
609 clk_div = WC_BAUD_DR48;
612 clk_div = WC_BAUD_DR24;
615 clk_div = WC_BAUD_DR12;
618 clk_div = WC_BAUD_DR6;
621 clk_div = WC_BAUD_DR3;
624 clk_div = WC_BAUD_DR2;
627 clk_div = WC_BAUD_DR1;
630 if (max->clock & MAX3110_HIGH_CLK)
633 /* Pick the previous baud rate */
635 clk_div = max->cur_conf & WC_BAUD_DIV_MASK;
636 tty_termios_encode_baud_rate(termios, baud, baud);
639 if (max->clock & MAX3110_HIGH_CLK) {
641 /* High clk version max3110 doesn't support B300 */
644 clk_div = WC_BAUD_DR384;
647 clk_div = WC_BAUD_DR1;
648 tty_termios_encode_baud_rate(termios, baud, baud);
651 new_conf = (new_conf & ~WC_BAUD_DIV_MASK) | clk_div;
653 if (unlikely(termios->c_cflag & CMSPAR))
654 termios->c_cflag &= ~CMSPAR;
656 if (termios->c_cflag & CSTOPB)
657 new_conf |= WC_2_STOPBITS;
659 new_conf &= ~WC_2_STOPBITS;
661 if (termios->c_cflag & PARENB) {
662 new_conf |= WC_PARITY_ENABLE;
663 parity |= UART_LCR_PARITY;
665 new_conf &= ~WC_PARITY_ENABLE;
667 if (!(termios->c_cflag & PARODD))
668 parity |= UART_LCR_EPAR;
669 max->parity = parity;
671 uart_update_timeout(port, termios->c_cflag, baud);
674 if (new_conf != max->cur_conf) {
675 if (!max3110_out(max, new_conf)) {
676 max->cur_conf = new_conf;
682 /* Don't handle hw handshaking */
683 static unsigned int serial_m3110_get_mctrl(struct uart_port *port)
685 return TIOCM_DSR | TIOCM_CAR | TIOCM_DSR;
688 static void serial_m3110_set_mctrl(struct uart_port *port, unsigned int mctrl)
692 static void serial_m3110_break_ctl(struct uart_port *port, int break_state)
696 static void serial_m3110_pm(struct uart_port *port, unsigned int state,
697 unsigned int oldstate)
701 static void serial_m3110_enable_ms(struct uart_port *port)
705 static struct uart_ops serial_m3110_ops = {
706 .tx_empty = serial_m3110_tx_empty,
707 .set_mctrl = serial_m3110_set_mctrl,
708 .get_mctrl = serial_m3110_get_mctrl,
709 .stop_tx = serial_m3110_stop_tx,
710 .start_tx = serial_m3110_start_tx,
711 .stop_rx = serial_m3110_stop_rx,
712 .enable_ms = serial_m3110_enable_ms,
713 .break_ctl = serial_m3110_break_ctl,
714 .startup = serial_m3110_startup,
715 .shutdown = serial_m3110_shutdown,
716 .set_termios = serial_m3110_set_termios,
717 .pm = serial_m3110_pm,
718 .type = serial_m3110_type,
719 .release_port = serial_m3110_release_port,
720 .request_port = serial_m3110_request_port,
721 .config_port = serial_m3110_config_port,
722 .verify_port = serial_m3110_verify_port,
725 static struct uart_driver serial_m3110_reg = {
726 .owner = THIS_MODULE,
727 .driver_name = "MRST serial",
732 .cons = &serial_m3110_console,
735 #ifdef CONFIG_PM_SLEEP
736 static int serial_m3110_suspend(struct device *dev)
738 struct spi_device *spi = to_spi_device(dev);
739 struct uart_max3110 *max = spi_get_drvdata(spi);
742 disable_irq(max->irq);
743 uart_suspend_port(&serial_m3110_reg, &max->port);
744 max3110_out(max, max->cur_conf | WC_SW_SHDI);
748 static int serial_m3110_resume(struct device *dev)
750 struct spi_device *spi = to_spi_device(dev);
751 struct uart_max3110 *max = spi_get_drvdata(spi);
753 max3110_out(max, max->cur_conf);
754 uart_resume_port(&serial_m3110_reg, &max->port);
756 enable_irq(max->irq);
760 static SIMPLE_DEV_PM_OPS(serial_m3110_pm_ops, serial_m3110_suspend,
761 serial_m3110_resume);
762 #define SERIAL_M3110_PM_OPS (&serial_m3110_pm_ops)
765 #define SERIAL_M3110_PM_OPS NULL
768 static int serial_m3110_probe(struct spi_device *spi)
770 struct uart_max3110 *max;
775 max = kzalloc(sizeof(*max), GFP_KERNEL);
780 spi->bits_per_word = 16;
781 max->clock = MAX3110_HIGH_CLK;
785 max->port.type = PORT_MAX3100;
786 max->port.fifosize = 2; /* Only have 16b buffer */
787 max->port.ops = &serial_m3110_ops;
789 max->port.dev = &spi->dev;
790 max->port.uartclk = 115200;
793 strcpy(max->name, spi->modalias);
794 max->irq = (u16)spi->irq;
796 mutex_init(&max->thread_mutex);
797 mutex_init(&max->io_mutex);
806 /* Check if reading configuration register returns something sane */
809 ret = max3110_write_then_read(max, (u8 *)&res, (u8 *)&res, 2, 0);
810 if (ret < 0 || res == 0 || res == 0xffff) {
811 dev_dbg(&spi->dev, "MAX3111 deemed not present (conf reg %04x)",
817 buffer = (void *)__get_free_page(GFP_KERNEL);
822 max->con_xmit.buf = buffer;
823 max->con_xmit.head = 0;
824 max->con_xmit.tail = 0;
826 init_waitqueue_head(&max->wq);
828 max->main_thread = kthread_run(max3110_main_thread,
829 max, "max3110_main");
830 if (IS_ERR(max->main_thread)) {
831 ret = PTR_ERR(max->main_thread);
836 ret = request_irq(max->irq, serial_m3110_irq,
837 IRQ_TYPE_EDGE_FALLING, "max3110", max);
841 "unable to allocate IRQ, will use polling method\n");
845 spi_set_drvdata(spi, max);
848 /* Give membase a psudo value to pass serial_core's check */
849 max->port.membase = (unsigned char __iomem *)0xff110000;
850 uart_add_one_port(&serial_m3110_reg, &max->port);
855 free_page((unsigned long)buffer);
861 static int serial_m3110_remove(struct spi_device *dev)
863 struct uart_max3110 *max = spi_get_drvdata(dev);
868 uart_remove_one_port(&serial_m3110_reg, &max->port);
870 free_page((unsigned long)max->con_xmit.buf);
873 free_irq(max->irq, max);
875 if (max->main_thread)
876 kthread_stop(max->main_thread);
882 static struct spi_driver uart_max3110_driver = {
884 .name = "spi_max3111",
885 .owner = THIS_MODULE,
886 .pm = SERIAL_M3110_PM_OPS,
888 .probe = serial_m3110_probe,
889 .remove = serial_m3110_remove,
892 static int __init serial_m3110_init(void)
896 ret = uart_register_driver(&serial_m3110_reg);
900 ret = spi_register_driver(&uart_max3110_driver);
902 uart_unregister_driver(&serial_m3110_reg);
907 static void __exit serial_m3110_exit(void)
909 spi_unregister_driver(&uart_max3110_driver);
910 uart_unregister_driver(&serial_m3110_reg);
913 module_init(serial_m3110_init);
914 module_exit(serial_m3110_exit);
916 MODULE_LICENSE("GPL v2");
917 MODULE_ALIAS("spi:max3110-uart");