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;
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 = tty_port_tty_get(&port->state->port);
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;
372 for (r = 0; w; r += usable, w -= usable) {
373 usable = tty_buffer_request_room(tty, w);
375 tty_insert_flip_string(tty, buf + r, usable);
376 port->icount.rx += usable;
379 tty_flip_buffer_push(tty);
386 * This routine will be used in read_thread or RX IRQ handling,
387 * it will first do one round buffer read(8 words), if there is some
388 * valid RX data, will try to read 5 more rounds till all data
391 * Use stack space as data buffer to save some system load, and chose
392 * 504 Btyes as a threadhold to do a bulk push to upper tty layer when
393 * receiving bulk data, a much bigger buffer may cause stack overflow
395 static void max3110_con_receive(struct uart_max3110 *max)
400 num = max3110_read_multi(max);
408 static int max3110_main_thread(void *_max)
410 struct uart_max3110 *max = _max;
411 wait_queue_head_t *wq = &max->wq;
413 struct circ_buf *xmit = &max->con_xmit;
415 pr_info(PR_FMT "start main thread\n");
418 wait_event_interruptible(*wq,
419 max->uart_flags || kthread_should_stop());
421 mutex_lock(&max->thread_mutex);
423 if (test_and_clear_bit(BIT_IRQ_PENDING, &max->uart_flags))
424 max3110_con_receive(max);
426 /* first handle console output */
427 if (test_and_clear_bit(CON_TX_NEEDED, &max->uart_flags))
428 send_circ_buf(max, xmit);
430 /* handle uart output */
431 if (test_and_clear_bit(UART_TX_NEEDED, &max->uart_flags))
434 mutex_unlock(&max->thread_mutex);
436 } while (!kthread_should_stop());
441 static irqreturn_t serial_m3110_irq(int irq, void *dev_id)
443 struct uart_max3110 *max = dev_id;
445 /* max3110's irq is a falling edge, not level triggered,
446 * so no need to disable the irq */
448 if (!test_and_set_bit(BIT_IRQ_PENDING, &max->uart_flags))
454 /* if don't use RX IRQ, then need a thread to polling read */
455 static int max3110_read_thread(void *_max)
457 struct uart_max3110 *max = _max;
459 pr_info(PR_FMT "start read thread\n");
462 * If can't acquire the mutex, it means the main thread
463 * is running which will also perform the rx job
465 if (mutex_trylock(&max->thread_mutex)) {
466 max3110_con_receive(max);
467 mutex_unlock(&max->thread_mutex);
470 set_current_state(TASK_INTERRUPTIBLE);
471 schedule_timeout(HZ / 20);
472 } while (!kthread_should_stop());
477 static int serial_m3110_startup(struct uart_port *port)
479 struct uart_max3110 *max =
480 container_of(port, struct uart_max3110, port);
484 if (port->line != 0) {
485 pr_err(PR_FMT "uart port startup failed\n");
489 /* Disable all IRQ and config it to 115200, 8n1 */
490 config = WC_TAG | WC_FIFO_ENABLE
495 /* as we use thread to handle tx/rx, need set low latency */
496 port->state->port.tty->low_latency = 1;
499 max->read_thread = NULL;
500 ret = request_irq(max->irq, serial_m3110_irq,
501 IRQ_TYPE_EDGE_FALLING, "max3110", max);
504 pr_err(PR_FMT "unable to allocate IRQ, polling\n");
506 /* Enable RX IRQ only */
507 config |= WC_RXA_IRQ_ENABLE;
512 /* If IRQ is disabled, start a read thread for input data */
514 kthread_run(max3110_read_thread, max, "max3110_read");
515 if (IS_ERR(max->read_thread)) {
516 ret = PTR_ERR(max->read_thread);
517 max->read_thread = NULL;
518 pr_err(PR_FMT "Can't create read thread!\n");
523 ret = max3110_out(max, config);
526 free_irq(max->irq, max);
527 if (max->read_thread)
528 kthread_stop(max->read_thread);
529 max->read_thread = NULL;
533 max->cur_conf = config;
537 static void serial_m3110_shutdown(struct uart_port *port)
539 struct uart_max3110 *max =
540 container_of(port, struct uart_max3110, port);
543 if (max->read_thread) {
544 kthread_stop(max->read_thread);
545 max->read_thread = NULL;
549 free_irq(max->irq, max);
551 /* Disable interrupts from this port */
552 config = WC_TAG | WC_SW_SHDI;
553 max3110_out(max, config);
556 static void serial_m3110_release_port(struct uart_port *port)
560 static int serial_m3110_request_port(struct uart_port *port)
565 static void serial_m3110_config_port(struct uart_port *port, int flags)
567 port->type = PORT_MAX3100;
571 serial_m3110_verify_port(struct uart_port *port, struct serial_struct *ser)
573 /* we don't want the core code to modify any port params */
578 static const char *serial_m3110_type(struct uart_port *port)
580 struct uart_max3110 *max =
581 container_of(port, struct uart_max3110, port);
586 serial_m3110_set_termios(struct uart_port *port, struct ktermios *termios,
587 struct ktermios *old)
589 struct uart_max3110 *max =
590 container_of(port, struct uart_max3110, port);
592 unsigned int baud, parity = 0;
594 u16 new_conf = max->cur_conf;
596 switch (termios->c_cflag & CSIZE) {
598 cval = UART_LCR_WLEN7;
599 new_conf |= WC_7BIT_WORD;
602 /* We only support CS7 & CS8 */
603 termios->c_cflag &= ~CSIZE;
604 termios->c_cflag |= CS8;
606 cval = UART_LCR_WLEN8;
607 new_conf |= WC_8BIT_WORD;
611 baud = uart_get_baud_rate(port, termios, old, 0, 230400);
613 /* First calc the div for 1.8MHZ clock case */
616 clk_div = WC_BAUD_DR384;
619 clk_div = WC_BAUD_DR192;
622 clk_div = WC_BAUD_DR96;
625 clk_div = WC_BAUD_DR48;
628 clk_div = WC_BAUD_DR24;
631 clk_div = WC_BAUD_DR12;
634 clk_div = WC_BAUD_DR6;
637 clk_div = WC_BAUD_DR3;
640 clk_div = WC_BAUD_DR2;
643 clk_div = WC_BAUD_DR1;
646 if (max->clock & MAX3110_HIGH_CLK)
649 /* Pick the previous baud rate */
651 clk_div = max->cur_conf & WC_BAUD_DIV_MASK;
652 tty_termios_encode_baud_rate(termios, baud, baud);
655 if (max->clock & MAX3110_HIGH_CLK) {
657 /* High clk version max3110 doesn't support B300 */
660 clk_div = WC_BAUD_DR384;
663 clk_div = WC_BAUD_DR1;
664 tty_termios_encode_baud_rate(termios, baud, baud);
667 new_conf = (new_conf & ~WC_BAUD_DIV_MASK) | clk_div;
669 if (unlikely(termios->c_cflag & CMSPAR))
670 termios->c_cflag &= ~CMSPAR;
672 if (termios->c_cflag & CSTOPB)
673 new_conf |= WC_2_STOPBITS;
675 new_conf &= ~WC_2_STOPBITS;
677 if (termios->c_cflag & PARENB) {
678 new_conf |= WC_PARITY_ENABLE;
679 parity |= UART_LCR_PARITY;
681 new_conf &= ~WC_PARITY_ENABLE;
683 if (!(termios->c_cflag & PARODD))
684 parity |= UART_LCR_EPAR;
685 max->parity = parity;
687 uart_update_timeout(port, termios->c_cflag, baud);
690 if (new_conf != max->cur_conf) {
691 if (!max3110_out(max, new_conf)) {
692 max->cur_conf = new_conf;
698 /* Don't handle hw handshaking */
699 static unsigned int serial_m3110_get_mctrl(struct uart_port *port)
701 return TIOCM_DSR | TIOCM_CAR | TIOCM_DSR;
704 static void serial_m3110_set_mctrl(struct uart_port *port, unsigned int mctrl)
708 static void serial_m3110_break_ctl(struct uart_port *port, int break_state)
712 static void serial_m3110_pm(struct uart_port *port, unsigned int state,
713 unsigned int oldstate)
717 static void serial_m3110_enable_ms(struct uart_port *port)
721 struct uart_ops serial_m3110_ops = {
722 .tx_empty = serial_m3110_tx_empty,
723 .set_mctrl = serial_m3110_set_mctrl,
724 .get_mctrl = serial_m3110_get_mctrl,
725 .stop_tx = serial_m3110_stop_tx,
726 .start_tx = serial_m3110_start_tx,
727 .stop_rx = serial_m3110_stop_rx,
728 .enable_ms = serial_m3110_enable_ms,
729 .break_ctl = serial_m3110_break_ctl,
730 .startup = serial_m3110_startup,
731 .shutdown = serial_m3110_shutdown,
732 .set_termios = serial_m3110_set_termios,
733 .pm = serial_m3110_pm,
734 .type = serial_m3110_type,
735 .release_port = serial_m3110_release_port,
736 .request_port = serial_m3110_request_port,
737 .config_port = serial_m3110_config_port,
738 .verify_port = serial_m3110_verify_port,
741 static struct uart_driver serial_m3110_reg = {
742 .owner = THIS_MODULE,
743 .driver_name = "MRST serial",
748 .cons = &serial_m3110_console,
752 static int serial_m3110_suspend(struct spi_device *spi, pm_message_t state)
754 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 spi_device *spi)
764 struct uart_max3110 *max = spi_get_drvdata(spi);
766 max3110_out(max, max->cur_conf);
767 uart_resume_port(&serial_m3110_reg, &max->port);
768 enable_irq(max->irq);
772 #define serial_m3110_suspend NULL
773 #define serial_m3110_resume NULL
776 static int serial_m3110_probe(struct spi_device *spi)
778 struct uart_max3110 *max;
783 max = kzalloc(sizeof(*max), GFP_KERNEL);
788 spi->bits_per_word = 16;
789 max->clock = MAX3110_HIGH_CLK;
793 max->port.type = PORT_MAX3100;
794 max->port.fifosize = 2; /* Only have 16b buffer */
795 max->port.ops = &serial_m3110_ops;
797 max->port.dev = &spi->dev;
798 max->port.uartclk = 115200;
801 strcpy(max->name, spi->modalias);
802 max->irq = (u16)spi->irq;
804 mutex_init(&max->thread_mutex);
813 /* Check if reading configuration register returns something sane */
816 ret = max3110_write_then_read(max, (u8 *)&res, (u8 *)&res, 2, 0);
817 if (ret < 0 || res == 0 || res == 0xffff) {
818 dev_dbg(&spi->dev, "MAX3111 deemed not present (conf reg %04x)",
824 buffer = (void *)__get_free_page(GFP_KERNEL);
829 max->con_xmit.buf = buffer;
830 max->con_xmit.head = 0;
831 max->con_xmit.tail = 0;
833 init_waitqueue_head(&max->wq);
835 max->main_thread = kthread_run(max3110_main_thread,
836 max, "max3110_main");
837 if (IS_ERR(max->main_thread)) {
838 ret = PTR_ERR(max->main_thread);
842 spi_set_drvdata(spi, max);
845 /* Give membase a psudo value to pass serial_core's check */
846 max->port.membase = (void *)0xff110000;
847 uart_add_one_port(&serial_m3110_reg, &max->port);
852 free_page((unsigned long)buffer);
858 static int serial_m3110_remove(struct spi_device *dev)
860 struct uart_max3110 *max = spi_get_drvdata(dev);
865 uart_remove_one_port(&serial_m3110_reg, &max->port);
867 free_page((unsigned long)max->con_xmit.buf);
869 if (max->main_thread)
870 kthread_stop(max->main_thread);
876 static struct spi_driver uart_max3110_driver = {
878 .name = "spi_max3111",
879 .owner = THIS_MODULE,
881 .probe = serial_m3110_probe,
882 .remove = serial_m3110_remove,
883 .suspend = serial_m3110_suspend,
884 .resume = serial_m3110_resume,
887 static int __init serial_m3110_init(void)
891 ret = uart_register_driver(&serial_m3110_reg);
895 ret = spi_register_driver(&uart_max3110_driver);
897 uart_unregister_driver(&serial_m3110_reg);
902 static void __exit serial_m3110_exit(void)
904 spi_unregister_driver(&uart_max3110_driver);
905 uart_unregister_driver(&serial_m3110_reg);
908 module_init(serial_m3110_init);
909 module_exit(serial_m3110_exit);
911 MODULE_LICENSE("GPL v2");
912 MODULE_ALIAS("spi:max3110-uart");