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(uart, reg) (uart->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;
105 int is_emulated; /* H/w vs. Instruction Set Simulator */
108 #define to_arc_port(uport) container_of(uport, struct arc_uart_port, port)
110 static struct arc_uart_port arc_uart_ports[CONFIG_SERIAL_ARC_NR_PORTS];
112 #ifdef CONFIG_SERIAL_ARC_CONSOLE
113 static struct console arc_console;
116 #define DRIVER_NAME "arc-uart"
118 static struct uart_driver arc_uart_driver = {
119 .owner = THIS_MODULE,
120 .driver_name = DRIVER_NAME,
121 .dev_name = ARC_SERIAL_DEV_NAME,
124 .nr = CONFIG_SERIAL_ARC_NR_PORTS,
125 #ifdef CONFIG_SERIAL_ARC_CONSOLE
126 .cons = &arc_console,
130 static void arc_serial_stop_rx(struct uart_port *port)
132 struct arc_uart_port *uart = to_arc_port(port);
134 UART_RX_IRQ_DISABLE(uart);
137 static void arc_serial_stop_tx(struct uart_port *port)
139 struct arc_uart_port *uart = to_arc_port(port);
141 while (!(UART_GET_STATUS(uart) & TXEMPTY))
144 UART_TX_IRQ_DISABLE(uart);
148 * Return TIOCSER_TEMT when transmitter is not busy.
150 static unsigned int arc_serial_tx_empty(struct uart_port *port)
152 struct arc_uart_port *uart = to_arc_port(port);
155 stat = UART_GET_STATUS(uart);
163 * Driver internal routine, used by both tty(serial core) as well as tx-isr
164 * -Called under spinlock in either cases
165 * -also tty->stopped has already been checked
166 * = by uart_start( ) before calling us
167 * = tx_ist checks that too before calling
169 static void arc_serial_tx_chars(struct arc_uart_port *uart)
171 struct circ_buf *xmit = &uart->port.state->xmit;
175 if (unlikely(uart->port.x_char)) {
176 UART_SET_DATA(uart, uart->port.x_char);
177 uart->port.icount.tx++;
178 uart->port.x_char = 0;
180 } else if (xmit->tail != xmit->head) { /* TODO: uart_circ_empty */
181 ch = xmit->buf[xmit->tail];
182 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
183 uart->port.icount.tx++;
184 while (!(UART_GET_STATUS(uart) & TXEMPTY))
186 UART_SET_DATA(uart, ch);
191 * If num chars in xmit buffer are too few, ask tty layer for more.
192 * By Hard ISR to schedule processing in software interrupt part
194 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
195 uart_write_wakeup(&uart->port);
198 UART_TX_IRQ_ENABLE(uart);
202 * port is locked and interrupts are disabled
203 * uart_start( ) calls us under the port spinlock irqsave
205 static void arc_serial_start_tx(struct uart_port *port)
207 struct arc_uart_port *uart = to_arc_port(port);
209 arc_serial_tx_chars(uart);
212 static void arc_serial_rx_chars(struct arc_uart_port *uart, unsigned int status)
214 unsigned int ch, flg = 0;
217 * UART has 4 deep RX-FIFO. Driver's recongnition of this fact
218 * is very subtle. Here's how ...
219 * Upon getting a RX-Intr, such that RX-EMPTY=0, meaning data available,
220 * driver reads the DATA Reg and keeps doing that in a loop, until
221 * RX-EMPTY=1. Multiple chars being avail, with a single Interrupt,
222 * before RX-EMPTY=0, implies some sort of buffering going on in the
223 * controller, which is indeed the Rx-FIFO.
227 * This could be an Rx Intr for err (no data),
228 * so check err and clear that Intr first
230 if (unlikely(status & (RXOERR | RXFERR))) {
231 if (status & RXOERR) {
232 uart->port.icount.overrun++;
234 UART_CLR_STATUS(uart, RXOERR);
237 if (status & RXFERR) {
238 uart->port.icount.frame++;
240 UART_CLR_STATUS(uart, RXFERR);
245 if (status & RXEMPTY)
248 ch = UART_GET_DATA(uart);
249 uart->port.icount.rx++;
251 if (!(uart_handle_sysrq_char(&uart->port, ch)))
252 uart_insert_char(&uart->port, status, RXOERR, ch, flg);
254 spin_unlock(&uart->port.lock);
255 tty_flip_buffer_push(&uart->port.state->port);
256 spin_lock(&uart->port.lock);
257 } while (!((status = UART_GET_STATUS(uart)) & RXEMPTY));
261 * A note on the Interrupt handling state machine of this driver
263 * kernel printk writes funnel thru the console driver framework and in order
264 * to keep things simple as well as efficient, it writes to UART in polled
265 * mode, in one shot, and exits.
267 * OTOH, Userland output (via tty layer), uses interrupt based writes as there
268 * can be undeterministic delay between char writes.
270 * Thus Rx-interrupts are always enabled, while tx-interrupts are by default
273 * When tty has some data to send out, serial core calls driver's start_tx
275 * -checks-if-tty-buffer-has-char-to-send
276 * -writes-data-to-uart
279 * Once data bits are pushed out, controller raises the Tx-room-avail-Interrupt.
280 * The first thing Tx ISR does is disable further Tx interrupts (as this could
281 * be the last char to send, before settling down into the quiet polled mode).
282 * It then calls the exact routine used by tty layer write to send out any
283 * more char in tty buffer. In case of sending, it re-enables Tx-intr. In case
284 * of no data, it remains disabled.
285 * This is how the transmit state machine is dynamically switched on/off
288 static irqreturn_t arc_serial_isr(int irq, void *dev_id)
290 struct arc_uart_port *uart = dev_id;
293 status = UART_GET_STATUS(uart);
296 * Single IRQ for both Rx (data available) Tx (room available) Interrupt
297 * notifications from the UART Controller.
298 * To demultiplex between the two, we check the relevant bits
300 if (status & RXIENB) {
302 /* already in ISR, no need of xx_irqsave */
303 spin_lock(&uart->port.lock);
304 arc_serial_rx_chars(uart, status);
305 spin_unlock(&uart->port.lock);
308 if ((status & TXIENB) && (status & TXEMPTY)) {
310 /* Unconditionally disable further Tx-Interrupts.
311 * will be enabled by tx_chars() if needed.
313 UART_TX_IRQ_DISABLE(uart);
315 spin_lock(&uart->port.lock);
317 if (!uart_tx_stopped(&uart->port))
318 arc_serial_tx_chars(uart);
320 spin_unlock(&uart->port.lock);
326 static unsigned int arc_serial_get_mctrl(struct uart_port *port)
329 * Pretend we have a Modem status reg and following bits are
330 * always set, to satify the serial core state machine
331 * (DSR) Data Set Ready
332 * (CTS) Clear To Send
333 * (CAR) Carrier Detect
335 return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
338 static void arc_serial_set_mctrl(struct uart_port *port, unsigned int mctrl)
340 /* MCR not present */
343 static void arc_serial_break_ctl(struct uart_port *port, int break_state)
345 /* ARC UART doesn't support sending Break signal */
348 static int arc_serial_startup(struct uart_port *port)
350 struct arc_uart_port *uart = to_arc_port(port);
352 /* Before we hook up the ISR, Disable all UART Interrupts */
353 UART_ALL_IRQ_DISABLE(uart);
355 if (request_irq(uart->port.irq, arc_serial_isr, 0, "arc uart rx-tx",
357 dev_warn(uart->port.dev, "Unable to attach ARC UART intr\n");
361 UART_RX_IRQ_ENABLE(uart); /* Only Rx IRQ enabled to begin with */
366 /* This is not really needed */
367 static void arc_serial_shutdown(struct uart_port *port)
369 struct arc_uart_port *uart = to_arc_port(port);
370 free_irq(uart->port.irq, uart);
374 arc_serial_set_termios(struct uart_port *port, struct ktermios *new,
375 struct ktermios *old)
377 struct arc_uart_port *uart = to_arc_port(port);
378 unsigned int baud, uartl, uarth, hw_val;
382 * Use the generic handler so that any specially encoded baud rates
383 * such as SPD_xx flags or "%B0" can be handled
384 * Max Baud I suppose will not be more than current 115K * 4
385 * Formula for ARC UART is: hw-val = ((CLK/(BAUD*4)) -1)
386 * spread over two 8-bit registers
388 baud = uart_get_baud_rate(port, new, old, 0, 460800);
390 hw_val = port->uartclk / (uart->baud * 4) - 1;
391 uartl = hw_val & 0xFF;
392 uarth = (hw_val >> 8) & 0xFF;
395 * UART ISS(Instruction Set simulator) emulation has a subtle bug:
396 * A existing value of Baudh = 0 is used as a indication to startup
397 * it's internal state machine.
398 * Thus if baudh is set to 0, 2 times, it chokes.
399 * This happens with BAUD=115200 and the formaula above
400 * Until that is fixed, when running on ISS, we will set baudh to !0
402 if (uart->is_emulated)
405 spin_lock_irqsave(&port->lock, flags);
407 UART_ALL_IRQ_DISABLE(uart);
409 UART_SET_BAUDL(uart, uartl);
410 UART_SET_BAUDH(uart, uarth);
412 UART_RX_IRQ_ENABLE(uart);
415 * UART doesn't support Parity/Hardware Flow Control;
416 * Only supports 8N1 character size
418 new->c_cflag &= ~(CMSPAR|CRTSCTS|CSIZE);
422 tty_termios_copy_hw(new, old);
424 /* Don't rewrite B0 */
425 if (tty_termios_baud_rate(new))
426 tty_termios_encode_baud_rate(new, baud, baud);
428 uart_update_timeout(port, new->c_cflag, baud);
430 spin_unlock_irqrestore(&port->lock, flags);
433 static const char *arc_serial_type(struct uart_port *port)
435 struct arc_uart_port *uart = to_arc_port(port);
437 return uart->port.type == PORT_ARC ? DRIVER_NAME : NULL;
440 static void arc_serial_release_port(struct uart_port *port)
444 static int arc_serial_request_port(struct uart_port *port)
450 * Verify the new serial_struct (for TIOCSSERIAL).
453 arc_serial_verify_port(struct uart_port *port, struct serial_struct *ser)
455 if (port->type != PORT_UNKNOWN && ser->type != PORT_ARC)
462 * Configure/autoconfigure the port.
464 static void arc_serial_config_port(struct uart_port *port, int flags)
466 struct arc_uart_port *uart = to_arc_port(port);
468 if (flags & UART_CONFIG_TYPE)
469 uart->port.type = PORT_ARC;
472 #if defined(CONFIG_CONSOLE_POLL) || defined(CONFIG_SERIAL_ARC_CONSOLE)
474 static void arc_serial_poll_putchar(struct uart_port *port, int chr)
476 struct arc_uart_port *uart = to_arc_port(port);
478 while (!(UART_GET_STATUS(uart) & TXEMPTY))
481 UART_SET_DATA(uart, (unsigned char)chr);
485 #ifdef CONFIG_CONSOLE_POLL
486 static int arc_serial_poll_getchar(struct uart_port *port)
488 struct arc_uart_port *uart = to_arc_port(port);
491 while (!(UART_GET_STATUS(uart) & RXEMPTY))
494 chr = UART_GET_DATA(uart);
499 static struct uart_ops arc_serial_pops = {
500 .tx_empty = arc_serial_tx_empty,
501 .set_mctrl = arc_serial_set_mctrl,
502 .get_mctrl = arc_serial_get_mctrl,
503 .stop_tx = arc_serial_stop_tx,
504 .start_tx = arc_serial_start_tx,
505 .stop_rx = arc_serial_stop_rx,
506 .break_ctl = arc_serial_break_ctl,
507 .startup = arc_serial_startup,
508 .shutdown = arc_serial_shutdown,
509 .set_termios = arc_serial_set_termios,
510 .type = arc_serial_type,
511 .release_port = arc_serial_release_port,
512 .request_port = arc_serial_request_port,
513 .config_port = arc_serial_config_port,
514 .verify_port = arc_serial_verify_port,
515 #ifdef CONFIG_CONSOLE_POLL
516 .poll_put_char = arc_serial_poll_putchar,
517 .poll_get_char = arc_serial_poll_getchar,
522 arc_uart_init_one(struct platform_device *pdev, int dev_id)
524 struct resource *res, *res2;
525 unsigned long *plat_data;
526 struct arc_uart_port *uart = &arc_uart_ports[dev_id];
528 plat_data = dev_get_platdata(&pdev->dev);
532 uart->is_emulated = !!plat_data[0]; /* workaround ISS bug */
534 if (is_early_platform_device(pdev)) {
535 uart->port.uartclk = plat_data[1];
536 uart->baud = plat_data[2];
538 struct device_node *np = pdev->dev.of_node;
541 if (of_property_read_u32(np, "clock-frequency", &val)) {
542 dev_err(&pdev->dev, "clock-frequency property NOTset\n");
545 uart->port.uartclk = val;
547 if (of_property_read_u32(np, "current-speed", &val)) {
548 dev_err(&pdev->dev, "current-speed property NOT set\n");
554 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
558 res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
562 uart->port.mapbase = res->start;
563 uart->port.membase = ioremap_nocache(res->start, resource_size(res));
564 if (!uart->port.membase)
565 /* No point of dev_err since UART itself is hosed here */
568 uart->port.irq = res2->start;
569 uart->port.dev = &pdev->dev;
570 uart->port.iotype = UPIO_MEM;
571 uart->port.flags = UPF_BOOT_AUTOCONF;
572 uart->port.line = dev_id;
573 uart->port.ops = &arc_serial_pops;
575 uart->port.fifosize = ARC_UART_TX_FIFO_SIZE;
578 * uart_insert_char( ) uses it in decideding whether to ignore a
579 * char or not. Explicitly setting it here, removes the subtelty
581 uart->port.ignore_status_mask = 0;
586 #ifdef CONFIG_SERIAL_ARC_CONSOLE
588 static int arc_serial_console_setup(struct console *co, char *options)
590 struct uart_port *port;
596 if (co->index < 0 || co->index >= CONFIG_SERIAL_ARC_NR_PORTS)
600 * The uart port backing the console (e.g. ttyARC1) might not have been
601 * init yet. If so, defer the console setup to after the port.
603 port = &arc_uart_ports[co->index].port;
608 uart_parse_options(options, &baud, &parity, &bits, &flow);
611 * Serial core will call port->ops->set_termios( )
612 * which will set the baud reg
614 return uart_set_options(port, co, baud, parity, bits, flow);
618 * Interrupts are disabled on entering
620 static void arc_serial_console_write(struct console *co, const char *s,
623 struct uart_port *port = &arc_uart_ports[co->index].port;
626 spin_lock_irqsave(&port->lock, flags);
627 uart_console_write(port, s, count, arc_serial_poll_putchar);
628 spin_unlock_irqrestore(&port->lock, flags);
631 static struct console arc_console = {
632 .name = ARC_SERIAL_DEV_NAME,
633 .write = arc_serial_console_write,
634 .device = uart_console_device,
635 .setup = arc_serial_console_setup,
636 .flags = CON_PRINTBUFFER,
638 .data = &arc_uart_driver
641 static __init void early_serial_write(struct console *con, const char *s,
644 struct uart_port *port = &arc_uart_ports[con->index].port;
646 uart_console_write(port, s, n, arc_serial_poll_putchar);
649 static struct console arc_early_serial_console __initdata = {
650 .name = "early_ARCuart",
651 .write = early_serial_write,
652 .flags = CON_PRINTBUFFER | CON_BOOT,
656 static int __init arc_serial_probe_earlyprintk(struct platform_device *pdev)
658 int dev_id = pdev->id < 0 ? 0 : pdev->id;
661 arc_early_serial_console.index = dev_id;
663 rc = arc_uart_init_one(pdev, dev_id);
665 panic("early console init failed\n");
667 arc_serial_console_setup(&arc_early_serial_console, NULL);
669 register_console(&arc_early_serial_console);
672 #endif /* CONFIG_SERIAL_ARC_CONSOLE */
674 static int arc_serial_probe(struct platform_device *pdev)
677 struct device_node *np = pdev->dev.of_node;
679 /* no device tree device */
683 dev_id = of_alias_get_id(np, "serial");
687 rc = arc_uart_init_one(pdev, dev_id);
691 rc = uart_add_one_port(&arc_uart_driver, &arc_uart_ports[dev_id].port);
695 static int arc_serial_remove(struct platform_device *pdev)
697 /* This will never be called */
701 static const struct of_device_id arc_uart_dt_ids[] = {
702 { .compatible = "snps,arc-uart" },
705 MODULE_DEVICE_TABLE(of, arc_uart_dt_ids);
707 static struct platform_driver arc_platform_driver = {
708 .probe = arc_serial_probe,
709 .remove = arc_serial_remove,
712 .owner = THIS_MODULE,
713 .of_match_table = arc_uart_dt_ids,
717 #ifdef CONFIG_SERIAL_ARC_CONSOLE
719 static struct platform_driver early_arc_platform_driver __initdata = {
720 .probe = arc_serial_probe_earlyprintk,
721 .remove = arc_serial_remove,
724 .owner = THIS_MODULE,
728 * Register an early platform driver of "earlyprintk" class.
729 * ARCH platform code installs the driver and probes the early devices
730 * The installation could rely on user specifying earlyprintk=xyx in cmd line
731 * or it could be done independently, for all "earlyprintk" class drivers.
732 * [see arch/arc/plat-arcfpga/platform.c]
734 early_platform_init("earlyprintk", &early_arc_platform_driver);
736 #endif /* CONFIG_SERIAL_ARC_CONSOLE */
738 static int __init arc_serial_init(void)
742 ret = uart_register_driver(&arc_uart_driver);
746 ret = platform_driver_register(&arc_platform_driver);
748 uart_unregister_driver(&arc_uart_driver);
753 static void __exit arc_serial_exit(void)
755 platform_driver_unregister(&arc_platform_driver);
756 uart_unregister_driver(&arc_uart_driver);
759 module_init(arc_serial_init);
760 module_exit(arc_serial_exit);
762 MODULE_LICENSE("GPL");
763 MODULE_ALIAS("platform:" DRIVER_NAME);
764 MODULE_AUTHOR("Vineet Gupta");
765 MODULE_DESCRIPTION("ARC(Synopsys) On-Chip(fpga) serial driver");