2 * ARC On-Chip(fpga) UART Driver
4 * Copyright (C) 2010-2012 Synopsys, Inc. (www.synopsys.com)
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
10 * vineetg: July 10th 2012
11 * -Decoupled the driver from arch/arc
12 * +Using platform_get_resource() for irq/membase (thx to bfin_uart.c)
13 * +Using early_platform_xxx() for early console (thx to mach-shmobile/xxx)
15 * Vineetg: Aug 21st 2010
16 * -Is uart_tx_stopped() not done in tty write path as it has already been
17 * taken care of, in serial core
19 * Vineetg: Aug 18th 2010
20 * -New Serial Core based ARC UART driver
21 * -Derived largely from blackfin driver albiet with some major tweaks
24 * -check if sysreq works
27 #if defined(CONFIG_SERIAL_ARC_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
31 #include <linux/module.h>
32 #include <linux/serial.h>
33 #include <linux/console.h>
34 #include <linux/sysrq.h>
35 #include <linux/platform_device.h>
36 #include <linux/tty.h>
37 #include <linux/tty_flip.h>
38 #include <linux/serial_core.h>
41 #include <linux/of_platform.h>
43 /*************************************
44 * ARC UART Hardware Specs
45 ************************************/
46 #define ARC_UART_TX_FIFO_SIZE 1
49 * UART Register set (this is not a Standards Compliant IP)
50 * Also each reg is Word aligned, but only 8 bits wide
61 /* Bits for UART Status Reg (R/W) */
62 #define RXIENB 0x04 /* Receive Interrupt Enable */
63 #define TXIENB 0x40 /* Transmit Interrupt Enable */
65 #define RXEMPTY 0x20 /* Receive FIFO Empty: No char receivede */
66 #define TXEMPTY 0x80 /* Transmit FIFO Empty, thus char can be written into */
68 #define RXFULL 0x08 /* Receive FIFO full */
69 #define RXFULL1 0x10 /* Receive FIFO has space for 1 char (tot space=4) */
71 #define RXFERR 0x01 /* Frame Error: Stop Bit not detected */
72 #define RXOERR 0x02 /* OverFlow Err: Char recv but RXFULL still set */
74 /* Uart bit fiddling helpers: lowest level */
75 #define RBASE(port, reg) (port->membase + reg)
76 #define UART_REG_SET(u, r, v) writeb((v), RBASE(u, r))
77 #define UART_REG_GET(u, r) readb(RBASE(u, r))
79 #define UART_REG_OR(u, r, v) UART_REG_SET(u, r, UART_REG_GET(u, r) | (v))
80 #define UART_REG_CLR(u, r, v) UART_REG_SET(u, r, UART_REG_GET(u, r) & ~(v))
82 /* Uart bit fiddling helpers: API level */
83 #define UART_SET_DATA(uart, val) UART_REG_SET(uart, R_DATA, val)
84 #define UART_GET_DATA(uart) UART_REG_GET(uart, R_DATA)
86 #define UART_SET_BAUDH(uart, val) UART_REG_SET(uart, R_BAUDH, val)
87 #define UART_SET_BAUDL(uart, val) UART_REG_SET(uart, R_BAUDL, val)
89 #define UART_CLR_STATUS(uart, val) UART_REG_CLR(uart, R_STS, val)
90 #define UART_GET_STATUS(uart) UART_REG_GET(uart, R_STS)
92 #define UART_ALL_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, RXIENB|TXIENB)
93 #define UART_RX_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, RXIENB)
94 #define UART_TX_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, TXIENB)
96 #define UART_ALL_IRQ_ENABLE(uart) UART_REG_OR(uart, R_STS, RXIENB|TXIENB)
97 #define UART_RX_IRQ_ENABLE(uart) UART_REG_OR(uart, R_STS, RXIENB)
98 #define UART_TX_IRQ_ENABLE(uart) UART_REG_OR(uart, R_STS, TXIENB)
100 #define ARC_SERIAL_DEV_NAME "ttyARC"
102 struct arc_uart_port {
103 struct uart_port port;
107 #define to_arc_port(uport) container_of(uport, struct arc_uart_port, port)
109 static struct arc_uart_port arc_uart_ports[CONFIG_SERIAL_ARC_NR_PORTS];
111 #ifdef CONFIG_SERIAL_ARC_CONSOLE
112 static struct console arc_console;
115 #define DRIVER_NAME "arc-uart"
117 static struct uart_driver arc_uart_driver = {
118 .owner = THIS_MODULE,
119 .driver_name = DRIVER_NAME,
120 .dev_name = ARC_SERIAL_DEV_NAME,
123 .nr = CONFIG_SERIAL_ARC_NR_PORTS,
124 #ifdef CONFIG_SERIAL_ARC_CONSOLE
125 .cons = &arc_console,
129 static void arc_serial_stop_rx(struct uart_port *port)
131 UART_RX_IRQ_DISABLE(port);
134 static void arc_serial_stop_tx(struct uart_port *port)
136 while (!(UART_GET_STATUS(port) & TXEMPTY))
139 UART_TX_IRQ_DISABLE(port);
143 * Return TIOCSER_TEMT when transmitter is not busy.
145 static unsigned int arc_serial_tx_empty(struct uart_port *port)
149 stat = UART_GET_STATUS(port);
157 * Driver internal routine, used by both tty(serial core) as well as tx-isr
158 * -Called under spinlock in either cases
159 * -also tty->stopped has already been checked
160 * = by uart_start( ) before calling us
161 * = tx_ist checks that too before calling
163 static void arc_serial_tx_chars(struct uart_port *port)
165 struct circ_buf *xmit = &port->state->xmit;
169 if (unlikely(port->x_char)) {
170 UART_SET_DATA(port, port->x_char);
174 } else if (xmit->tail != xmit->head) { /* TODO: uart_circ_empty */
175 ch = xmit->buf[xmit->tail];
176 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
178 while (!(UART_GET_STATUS(port) & TXEMPTY))
180 UART_SET_DATA(port, ch);
185 * If num chars in xmit buffer are too few, ask tty layer for more.
186 * By Hard ISR to schedule processing in software interrupt part
188 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
189 uart_write_wakeup(port);
192 UART_TX_IRQ_ENABLE(port);
196 * port is locked and interrupts are disabled
197 * uart_start( ) calls us under the port spinlock irqsave
199 static void arc_serial_start_tx(struct uart_port *port)
201 arc_serial_tx_chars(port);
204 static void arc_serial_rx_chars(struct uart_port *port, unsigned int status)
206 unsigned int ch, flg = 0;
209 * UART has 4 deep RX-FIFO. Driver's recongnition of this fact
210 * is very subtle. Here's how ...
211 * Upon getting a RX-Intr, such that RX-EMPTY=0, meaning data available,
212 * driver reads the DATA Reg and keeps doing that in a loop, until
213 * RX-EMPTY=1. Multiple chars being avail, with a single Interrupt,
214 * before RX-EMPTY=0, implies some sort of buffering going on in the
215 * controller, which is indeed the Rx-FIFO.
219 * This could be an Rx Intr for err (no data),
220 * so check err and clear that Intr first
222 if (unlikely(status & (RXOERR | RXFERR))) {
223 if (status & RXOERR) {
224 port->icount.overrun++;
226 UART_CLR_STATUS(port, RXOERR);
229 if (status & RXFERR) {
230 port->icount.frame++;
232 UART_CLR_STATUS(port, RXFERR);
237 if (status & RXEMPTY)
240 ch = UART_GET_DATA(port);
243 if (!(uart_handle_sysrq_char(port, ch)))
244 uart_insert_char(port, status, RXOERR, ch, flg);
246 spin_unlock(&port->lock);
247 tty_flip_buffer_push(&port->state->port);
248 spin_lock(&port->lock);
249 } while (!((status = UART_GET_STATUS(port)) & RXEMPTY));
253 * A note on the Interrupt handling state machine of this driver
255 * kernel printk writes funnel thru the console driver framework and in order
256 * to keep things simple as well as efficient, it writes to UART in polled
257 * mode, in one shot, and exits.
259 * OTOH, Userland output (via tty layer), uses interrupt based writes as there
260 * can be undeterministic delay between char writes.
262 * Thus Rx-interrupts are always enabled, while tx-interrupts are by default
265 * When tty has some data to send out, serial core calls driver's start_tx
267 * -checks-if-tty-buffer-has-char-to-send
268 * -writes-data-to-uart
271 * Once data bits are pushed out, controller raises the Tx-room-avail-Interrupt.
272 * The first thing Tx ISR does is disable further Tx interrupts (as this could
273 * be the last char to send, before settling down into the quiet polled mode).
274 * It then calls the exact routine used by tty layer write to send out any
275 * more char in tty buffer. In case of sending, it re-enables Tx-intr. In case
276 * of no data, it remains disabled.
277 * This is how the transmit state machine is dynamically switched on/off
280 static irqreturn_t arc_serial_isr(int irq, void *dev_id)
282 struct uart_port *port = dev_id;
285 status = UART_GET_STATUS(port);
288 * Single IRQ for both Rx (data available) Tx (room available) Interrupt
289 * notifications from the UART Controller.
290 * To demultiplex between the two, we check the relevant bits
292 if (status & RXIENB) {
294 /* already in ISR, no need of xx_irqsave */
295 spin_lock(&port->lock);
296 arc_serial_rx_chars(port, status);
297 spin_unlock(&port->lock);
300 if ((status & TXIENB) && (status & TXEMPTY)) {
302 /* Unconditionally disable further Tx-Interrupts.
303 * will be enabled by tx_chars() if needed.
305 UART_TX_IRQ_DISABLE(port);
307 spin_lock(&port->lock);
309 if (!uart_tx_stopped(port))
310 arc_serial_tx_chars(port);
312 spin_unlock(&port->lock);
318 static unsigned int arc_serial_get_mctrl(struct uart_port *port)
321 * Pretend we have a Modem status reg and following bits are
322 * always set, to satify the serial core state machine
323 * (DSR) Data Set Ready
324 * (CTS) Clear To Send
325 * (CAR) Carrier Detect
327 return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
330 static void arc_serial_set_mctrl(struct uart_port *port, unsigned int mctrl)
332 /* MCR not present */
335 static void arc_serial_break_ctl(struct uart_port *port, int break_state)
337 /* ARC UART doesn't support sending Break signal */
340 static int arc_serial_startup(struct uart_port *port)
342 /* Before we hook up the ISR, Disable all UART Interrupts */
343 UART_ALL_IRQ_DISABLE(port);
345 if (request_irq(port->irq, arc_serial_isr, 0, "arc uart rx-tx", port)) {
346 dev_warn(port->dev, "Unable to attach ARC UART intr\n");
350 UART_RX_IRQ_ENABLE(port); /* Only Rx IRQ enabled to begin with */
355 /* This is not really needed */
356 static void arc_serial_shutdown(struct uart_port *port)
358 free_irq(port->irq, port);
362 arc_serial_set_termios(struct uart_port *port, struct ktermios *new,
363 struct ktermios *old)
365 struct arc_uart_port *uart = to_arc_port(port);
366 unsigned int baud, uartl, uarth, hw_val;
370 * Use the generic handler so that any specially encoded baud rates
371 * such as SPD_xx flags or "%B0" can be handled
372 * Max Baud I suppose will not be more than current 115K * 4
373 * Formula for ARC UART is: hw-val = ((CLK/(BAUD*4)) -1)
374 * spread over two 8-bit registers
376 baud = uart_get_baud_rate(port, new, old, 0, 460800);
378 hw_val = port->uartclk / (uart->baud * 4) - 1;
379 uartl = hw_val & 0xFF;
380 uarth = (hw_val >> 8) & 0xFF;
382 spin_lock_irqsave(&port->lock, flags);
384 UART_ALL_IRQ_DISABLE(port);
386 UART_SET_BAUDL(port, uartl);
387 UART_SET_BAUDH(port, uarth);
389 UART_RX_IRQ_ENABLE(port);
392 * UART doesn't support Parity/Hardware Flow Control;
393 * Only supports 8N1 character size
395 new->c_cflag &= ~(CMSPAR|CRTSCTS|CSIZE);
399 tty_termios_copy_hw(new, old);
401 /* Don't rewrite B0 */
402 if (tty_termios_baud_rate(new))
403 tty_termios_encode_baud_rate(new, baud, baud);
405 uart_update_timeout(port, new->c_cflag, baud);
407 spin_unlock_irqrestore(&port->lock, flags);
410 static const char *arc_serial_type(struct uart_port *port)
412 return port->type == PORT_ARC ? DRIVER_NAME : NULL;
415 static void arc_serial_release_port(struct uart_port *port)
419 static int arc_serial_request_port(struct uart_port *port)
425 * Verify the new serial_struct (for TIOCSSERIAL).
428 arc_serial_verify_port(struct uart_port *port, struct serial_struct *ser)
430 if (port->type != PORT_UNKNOWN && ser->type != PORT_ARC)
437 * Configure/autoconfigure the port.
439 static void arc_serial_config_port(struct uart_port *port, int flags)
441 if (flags & UART_CONFIG_TYPE)
442 port->type = PORT_ARC;
445 #if defined(CONFIG_CONSOLE_POLL) || defined(CONFIG_SERIAL_ARC_CONSOLE)
447 static void arc_serial_poll_putchar(struct uart_port *port, int chr)
449 while (!(UART_GET_STATUS(port) & TXEMPTY))
452 UART_SET_DATA(port, (unsigned char)chr);
456 #ifdef CONFIG_CONSOLE_POLL
457 static int arc_serial_poll_getchar(struct uart_port *port)
461 while (!(UART_GET_STATUS(port) & RXEMPTY))
464 chr = UART_GET_DATA(port);
469 static struct uart_ops arc_serial_pops = {
470 .tx_empty = arc_serial_tx_empty,
471 .set_mctrl = arc_serial_set_mctrl,
472 .get_mctrl = arc_serial_get_mctrl,
473 .stop_tx = arc_serial_stop_tx,
474 .start_tx = arc_serial_start_tx,
475 .stop_rx = arc_serial_stop_rx,
476 .break_ctl = arc_serial_break_ctl,
477 .startup = arc_serial_startup,
478 .shutdown = arc_serial_shutdown,
479 .set_termios = arc_serial_set_termios,
480 .type = arc_serial_type,
481 .release_port = arc_serial_release_port,
482 .request_port = arc_serial_request_port,
483 .config_port = arc_serial_config_port,
484 .verify_port = arc_serial_verify_port,
485 #ifdef CONFIG_CONSOLE_POLL
486 .poll_put_char = arc_serial_poll_putchar,
487 .poll_get_char = arc_serial_poll_getchar,
492 arc_uart_init_one(struct platform_device *pdev, int dev_id)
494 struct resource *res, *res2;
495 unsigned long *plat_data;
496 struct arc_uart_port *uart = &arc_uart_ports[dev_id];
497 struct uart_port *port = &uart->port;
499 plat_data = dev_get_platdata(&pdev->dev);
503 if (is_early_platform_device(pdev)) {
504 port->uartclk = plat_data[1];
505 uart->baud = plat_data[2];
507 struct device_node *np = pdev->dev.of_node;
510 if (of_property_read_u32(np, "clock-frequency", &val)) {
511 dev_err(&pdev->dev, "clock-frequency property NOTset\n");
516 if (of_property_read_u32(np, "current-speed", &val)) {
517 dev_err(&pdev->dev, "current-speed property NOT set\n");
523 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
527 res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
531 port->mapbase = res->start;
532 port->membase = ioremap_nocache(res->start, resource_size(res));
534 /* No point of dev_err since UART itself is hosed here */
537 port->irq = res2->start;
538 port->dev = &pdev->dev;
539 port->iotype = UPIO_MEM;
540 port->flags = UPF_BOOT_AUTOCONF;
542 port->ops = &arc_serial_pops;
544 port->fifosize = ARC_UART_TX_FIFO_SIZE;
547 * uart_insert_char( ) uses it in decideding whether to ignore a
548 * char or not. Explicitly setting it here, removes the subtelty
550 port->ignore_status_mask = 0;
555 #ifdef CONFIG_SERIAL_ARC_CONSOLE
557 static int arc_serial_console_setup(struct console *co, char *options)
559 struct uart_port *port;
565 if (co->index < 0 || co->index >= CONFIG_SERIAL_ARC_NR_PORTS)
569 * The uart port backing the console (e.g. ttyARC1) might not have been
570 * init yet. If so, defer the console setup to after the port.
572 port = &arc_uart_ports[co->index].port;
577 uart_parse_options(options, &baud, &parity, &bits, &flow);
580 * Serial core will call port->ops->set_termios( )
581 * which will set the baud reg
583 return uart_set_options(port, co, baud, parity, bits, flow);
587 * Interrupts are disabled on entering
589 static void arc_serial_console_write(struct console *co, const char *s,
592 struct uart_port *port = &arc_uart_ports[co->index].port;
595 spin_lock_irqsave(&port->lock, flags);
596 uart_console_write(port, s, count, arc_serial_poll_putchar);
597 spin_unlock_irqrestore(&port->lock, flags);
600 static struct console arc_console = {
601 .name = ARC_SERIAL_DEV_NAME,
602 .write = arc_serial_console_write,
603 .device = uart_console_device,
604 .setup = arc_serial_console_setup,
605 .flags = CON_PRINTBUFFER,
607 .data = &arc_uart_driver
610 static __init void early_serial_write(struct console *con, const char *s,
613 struct uart_port *port = &arc_uart_ports[con->index].port;
615 uart_console_write(port, s, n, arc_serial_poll_putchar);
618 static struct console arc_early_serial_console __initdata = {
619 .name = "early_ARCuart",
620 .write = early_serial_write,
621 .flags = CON_PRINTBUFFER | CON_BOOT,
625 static int __init arc_serial_probe_earlyprintk(struct platform_device *pdev)
627 int dev_id = pdev->id < 0 ? 0 : pdev->id;
630 arc_early_serial_console.index = dev_id;
632 rc = arc_uart_init_one(pdev, dev_id);
634 panic("early console init failed\n");
636 arc_serial_console_setup(&arc_early_serial_console, NULL);
638 register_console(&arc_early_serial_console);
642 static __init void arc_early_serial_write(struct console *con, const char *s,
645 struct earlycon_device *dev = con->data;
647 uart_console_write(&dev->port, s, n, arc_serial_poll_putchar);
650 static int __init arc_early_console_setup(struct earlycon_device *dev,
653 struct uart_port *port = &dev->port;
654 unsigned int l, h, hw_val;
656 if (!dev->port.membase)
659 hw_val = port->uartclk / (dev->baud * 4) - 1;
661 h = (hw_val >> 8) & 0xFF;
663 UART_SET_BAUDL(port, l);
664 UART_SET_BAUDH(port, h);
666 dev->con->write = arc_early_serial_write;
669 EARLYCON_DECLARE(arc_uart, arc_early_console_setup);
671 #endif /* CONFIG_SERIAL_ARC_CONSOLE */
673 static int arc_serial_probe(struct platform_device *pdev)
676 struct device_node *np = pdev->dev.of_node;
678 /* no device tree device */
682 dev_id = of_alias_get_id(np, "serial");
686 rc = arc_uart_init_one(pdev, dev_id);
690 rc = uart_add_one_port(&arc_uart_driver, &arc_uart_ports[dev_id].port);
694 static int arc_serial_remove(struct platform_device *pdev)
696 /* This will never be called */
700 static const struct of_device_id arc_uart_dt_ids[] = {
701 { .compatible = "snps,arc-uart" },
704 MODULE_DEVICE_TABLE(of, arc_uart_dt_ids);
706 static struct platform_driver arc_platform_driver = {
707 .probe = arc_serial_probe,
708 .remove = arc_serial_remove,
711 .owner = THIS_MODULE,
712 .of_match_table = arc_uart_dt_ids,
716 #ifdef CONFIG_SERIAL_ARC_CONSOLE
718 static struct platform_driver early_arc_platform_driver __initdata = {
719 .probe = arc_serial_probe_earlyprintk,
720 .remove = arc_serial_remove,
723 .owner = THIS_MODULE,
727 * Register an early platform driver of "earlyprintk" class.
728 * ARCH platform code installs the driver and probes the early devices
729 * The installation could rely on user specifying earlyprintk=xyx in cmd line
730 * or it could be done independently, for all "earlyprintk" class drivers.
731 * [see arch/arc/plat-arcfpga/platform.c]
733 early_platform_init("earlyprintk", &early_arc_platform_driver);
735 #endif /* CONFIG_SERIAL_ARC_CONSOLE */
737 static int __init arc_serial_init(void)
741 ret = uart_register_driver(&arc_uart_driver);
745 ret = platform_driver_register(&arc_platform_driver);
747 uart_unregister_driver(&arc_uart_driver);
752 static void __exit arc_serial_exit(void)
754 platform_driver_unregister(&arc_platform_driver);
755 uart_unregister_driver(&arc_uart_driver);
758 module_init(arc_serial_init);
759 module_exit(arc_serial_exit);
761 MODULE_LICENSE("GPL");
762 MODULE_ALIAS("platform:" DRIVER_NAME);
763 MODULE_AUTHOR("Vineet Gupta");
764 MODULE_DESCRIPTION("ARC(Synopsys) On-Chip(fpga) serial driver");