xref: /linux/drivers/tty/serial/timbuart.c (revision c4ee0af3fa0dc65f690fc908f02b8355f9576ea0) 
1 /*
2  * timbuart.c timberdale FPGA UART driver
3  * Copyright (c) 2009 Intel Corporation
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License version 2 as
7  * published by the Free Software Foundation.
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
17  */
18 
19 /* Supports:
20  * Timberdale FPGA UART
21  */
22 
23 #include <linux/pci.h>
24 #include <linux/interrupt.h>
25 #include <linux/serial_core.h>
26 #include <linux/tty.h>
27 #include <linux/tty_flip.h>
28 #include <linux/kernel.h>
29 #include <linux/platform_device.h>
30 #include <linux/ioport.h>
31 #include <linux/slab.h>
32 #include <linux/module.h>
33 
34 #include "timbuart.h"
35 
36 struct timbuart_port {
37 	struct uart_port	port;
38 	struct tasklet_struct	tasklet;
39 	int			usedma;
40 	u32			last_ier;
41 	struct platform_device  *dev;
42 };
43 
44 static int baudrates[] = {9600, 19200, 38400, 57600, 115200, 230400, 460800,
45 	921600, 1843200, 3250000};
46 
47 static void timbuart_mctrl_check(struct uart_port *port, u32 isr, u32 *ier);
48 
49 static irqreturn_t timbuart_handleinterrupt(int irq, void *devid);
50 
51 static void timbuart_stop_rx(struct uart_port *port)
52 {
53 	/* spin lock held by upper layer, disable all RX interrupts */
54 	u32 ier = ioread32(port->membase + TIMBUART_IER) & ~RXFLAGS;
55 	iowrite32(ier, port->membase + TIMBUART_IER);
56 }
57 
58 static void timbuart_stop_tx(struct uart_port *port)
59 {
60 	/* spinlock held by upper layer, disable TX interrupt */
61 	u32 ier = ioread32(port->membase + TIMBUART_IER) & ~TXBAE;
62 	iowrite32(ier, port->membase + TIMBUART_IER);
63 }
64 
65 static void timbuart_start_tx(struct uart_port *port)
66 {
67 	struct timbuart_port *uart =
68 		container_of(port, struct timbuart_port, port);
69 
70 	/* do not transfer anything here -> fire off the tasklet */
71 	tasklet_schedule(&uart->tasklet);
72 }
73 
74 static unsigned int timbuart_tx_empty(struct uart_port *port)
75 {
76 	u32 isr = ioread32(port->membase + TIMBUART_ISR);
77 
78 	return (isr & TXBE) ? TIOCSER_TEMT : 0;
79 }
80 
81 static void timbuart_flush_buffer(struct uart_port *port)
82 {
83 	if (!timbuart_tx_empty(port)) {
84 		u8 ctl = ioread8(port->membase + TIMBUART_CTRL) |
85 			TIMBUART_CTRL_FLSHTX;
86 
87 		iowrite8(ctl, port->membase + TIMBUART_CTRL);
88 		iowrite32(TXBF, port->membase + TIMBUART_ISR);
89 	}
90 }
91 
92 static void timbuart_rx_chars(struct uart_port *port)
93 {
94 	struct tty_port *tport = &port->state->port;
95 
96 	while (ioread32(port->membase + TIMBUART_ISR) & RXDP) {
97 		u8 ch = ioread8(port->membase + TIMBUART_RXFIFO);
98 		port->icount.rx++;
99 		tty_insert_flip_char(tport, ch, TTY_NORMAL);
100 	}
101 
102 	spin_unlock(&port->lock);
103 	tty_flip_buffer_push(tport);
104 	spin_lock(&port->lock);
105 
106 	dev_dbg(port->dev, "%s - total read %d bytes\n",
107 		__func__, port->icount.rx);
108 }
109 
110 static void timbuart_tx_chars(struct uart_port *port)
111 {
112 	struct circ_buf *xmit = &port->state->xmit;
113 
114 	while (!(ioread32(port->membase + TIMBUART_ISR) & TXBF) &&
115 		!uart_circ_empty(xmit)) {
116 		iowrite8(xmit->buf[xmit->tail],
117 			port->membase + TIMBUART_TXFIFO);
118 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
119 		port->icount.tx++;
120 	}
121 
122 	dev_dbg(port->dev,
123 		"%s - total written %d bytes, CTL: %x, RTS: %x, baud: %x\n",
124 		 __func__,
125 		port->icount.tx,
126 		ioread8(port->membase + TIMBUART_CTRL),
127 		port->mctrl & TIOCM_RTS,
128 		ioread8(port->membase + TIMBUART_BAUDRATE));
129 }
130 
131 static void timbuart_handle_tx_port(struct uart_port *port, u32 isr, u32 *ier)
132 {
133 	struct timbuart_port *uart =
134 		container_of(port, struct timbuart_port, port);
135 	struct circ_buf *xmit = &port->state->xmit;
136 
137 	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
138 		return;
139 
140 	if (port->x_char)
141 		return;
142 
143 	if (isr & TXFLAGS) {
144 		timbuart_tx_chars(port);
145 		/* clear all TX interrupts */
146 		iowrite32(TXFLAGS, port->membase + TIMBUART_ISR);
147 
148 		if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
149 			uart_write_wakeup(port);
150 	} else
151 		/* Re-enable any tx interrupt */
152 		*ier |= uart->last_ier & TXFLAGS;
153 
154 	/* enable interrupts if there are chars in the transmit buffer,
155 	 * Or if we delivered some bytes and want the almost empty interrupt
156 	 * we wake up the upper layer later when we got the interrupt
157 	 * to give it some time to go out...
158 	 */
159 	if (!uart_circ_empty(xmit))
160 		*ier |= TXBAE;
161 
162 	dev_dbg(port->dev, "%s - leaving\n", __func__);
163 }
164 
165 static void timbuart_handle_rx_port(struct uart_port *port, u32 isr, u32 *ier)
166 {
167 	if (isr & RXFLAGS) {
168 		/* Some RX status is set */
169 		if (isr & RXBF) {
170 			u8 ctl = ioread8(port->membase + TIMBUART_CTRL) |
171 				TIMBUART_CTRL_FLSHRX;
172 			iowrite8(ctl, port->membase + TIMBUART_CTRL);
173 			port->icount.overrun++;
174 		} else if (isr & (RXDP))
175 			timbuart_rx_chars(port);
176 
177 		/* ack all RX interrupts */
178 		iowrite32(RXFLAGS, port->membase + TIMBUART_ISR);
179 	}
180 
181 	/* always have the RX interrupts enabled */
182 	*ier |= RXBAF | RXBF | RXTT;
183 
184 	dev_dbg(port->dev, "%s - leaving\n", __func__);
185 }
186 
187 static void timbuart_tasklet(unsigned long arg)
188 {
189 	struct timbuart_port *uart = (struct timbuart_port *)arg;
190 	u32 isr, ier = 0;
191 
192 	spin_lock(&uart->port.lock);
193 
194 	isr = ioread32(uart->port.membase + TIMBUART_ISR);
195 	dev_dbg(uart->port.dev, "%s ISR: %x\n", __func__, isr);
196 
197 	if (!uart->usedma)
198 		timbuart_handle_tx_port(&uart->port, isr, &ier);
199 
200 	timbuart_mctrl_check(&uart->port, isr, &ier);
201 
202 	if (!uart->usedma)
203 		timbuart_handle_rx_port(&uart->port, isr, &ier);
204 
205 	iowrite32(ier, uart->port.membase + TIMBUART_IER);
206 
207 	spin_unlock(&uart->port.lock);
208 	dev_dbg(uart->port.dev, "%s leaving\n", __func__);
209 }
210 
211 static unsigned int timbuart_get_mctrl(struct uart_port *port)
212 {
213 	u8 cts = ioread8(port->membase + TIMBUART_CTRL);
214 	dev_dbg(port->dev, "%s - cts %x\n", __func__, cts);
215 
216 	if (cts & TIMBUART_CTRL_CTS)
217 		return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
218 	else
219 		return TIOCM_DSR | TIOCM_CAR;
220 }
221 
222 static void timbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
223 {
224 	dev_dbg(port->dev, "%s - %x\n", __func__, mctrl);
225 
226 	if (mctrl & TIOCM_RTS)
227 		iowrite8(TIMBUART_CTRL_RTS, port->membase + TIMBUART_CTRL);
228 	else
229 		iowrite8(0, port->membase + TIMBUART_CTRL);
230 }
231 
232 static void timbuart_mctrl_check(struct uart_port *port, u32 isr, u32 *ier)
233 {
234 	unsigned int cts;
235 
236 	if (isr & CTS_DELTA) {
237 		/* ack */
238 		iowrite32(CTS_DELTA, port->membase + TIMBUART_ISR);
239 		cts = timbuart_get_mctrl(port);
240 		uart_handle_cts_change(port, cts & TIOCM_CTS);
241 		wake_up_interruptible(&port->state->port.delta_msr_wait);
242 	}
243 
244 	*ier |= CTS_DELTA;
245 }
246 
247 static void timbuart_enable_ms(struct uart_port *port)
248 {
249 	/* N/A */
250 }
251 
252 static void timbuart_break_ctl(struct uart_port *port, int ctl)
253 {
254 	/* N/A */
255 }
256 
257 static int timbuart_startup(struct uart_port *port)
258 {
259 	struct timbuart_port *uart =
260 		container_of(port, struct timbuart_port, port);
261 
262 	dev_dbg(port->dev, "%s\n", __func__);
263 
264 	iowrite8(TIMBUART_CTRL_FLSHRX, port->membase + TIMBUART_CTRL);
265 	iowrite32(0x1ff, port->membase + TIMBUART_ISR);
266 	/* Enable all but TX interrupts */
267 	iowrite32(RXBAF | RXBF | RXTT | CTS_DELTA,
268 		port->membase + TIMBUART_IER);
269 
270 	return request_irq(port->irq, timbuart_handleinterrupt, IRQF_SHARED,
271 		"timb-uart", uart);
272 }
273 
274 static void timbuart_shutdown(struct uart_port *port)
275 {
276 	struct timbuart_port *uart =
277 		container_of(port, struct timbuart_port, port);
278 	dev_dbg(port->dev, "%s\n", __func__);
279 	free_irq(port->irq, uart);
280 	iowrite32(0, port->membase + TIMBUART_IER);
281 }
282 
283 static int get_bindex(int baud)
284 {
285 	int i;
286 
287 	for (i = 0; i < ARRAY_SIZE(baudrates); i++)
288 		if (baud <= baudrates[i])
289 			return i;
290 
291 	return -1;
292 }
293 
294 static void timbuart_set_termios(struct uart_port *port,
295 	struct ktermios *termios,
296 	struct ktermios *old)
297 {
298 	unsigned int baud;
299 	short bindex;
300 	unsigned long flags;
301 
302 	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
303 	bindex = get_bindex(baud);
304 	dev_dbg(port->dev, "%s - bindex %d\n", __func__, bindex);
305 
306 	if (bindex < 0)
307 		bindex = 0;
308 	baud = baudrates[bindex];
309 
310 	/* The serial layer calls into this once with old = NULL when setting
311 	   up initially */
312 	if (old)
313 		tty_termios_copy_hw(termios, old);
314 	tty_termios_encode_baud_rate(termios, baud, baud);
315 
316 	spin_lock_irqsave(&port->lock, flags);
317 	iowrite8((u8)bindex, port->membase + TIMBUART_BAUDRATE);
318 	uart_update_timeout(port, termios->c_cflag, baud);
319 	spin_unlock_irqrestore(&port->lock, flags);
320 }
321 
322 static const char *timbuart_type(struct uart_port *port)
323 {
324 	return port->type == PORT_UNKNOWN ? "timbuart" : NULL;
325 }
326 
327 /* We do not request/release mappings of the registers here,
328  * currently it's done in the proble function.
329  */
330 static void timbuart_release_port(struct uart_port *port)
331 {
332 	struct platform_device *pdev = to_platform_device(port->dev);
333 	int size =
334 		resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
335 
336 	if (port->flags & UPF_IOREMAP) {
337 		iounmap(port->membase);
338 		port->membase = NULL;
339 	}
340 
341 	release_mem_region(port->mapbase, size);
342 }
343 
344 static int timbuart_request_port(struct uart_port *port)
345 {
346 	struct platform_device *pdev = to_platform_device(port->dev);
347 	int size =
348 		resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
349 
350 	if (!request_mem_region(port->mapbase, size, "timb-uart"))
351 		return -EBUSY;
352 
353 	if (port->flags & UPF_IOREMAP) {
354 		port->membase = ioremap(port->mapbase, size);
355 		if (port->membase == NULL) {
356 			release_mem_region(port->mapbase, size);
357 			return -ENOMEM;
358 		}
359 	}
360 
361 	return 0;
362 }
363 
364 static irqreturn_t timbuart_handleinterrupt(int irq, void *devid)
365 {
366 	struct timbuart_port *uart = (struct timbuart_port *)devid;
367 
368 	if (ioread8(uart->port.membase + TIMBUART_IPR)) {
369 		uart->last_ier = ioread32(uart->port.membase + TIMBUART_IER);
370 
371 		/* disable interrupts, the tasklet enables them again */
372 		iowrite32(0, uart->port.membase + TIMBUART_IER);
373 
374 		/* fire off bottom half */
375 		tasklet_schedule(&uart->tasklet);
376 
377 		return IRQ_HANDLED;
378 	} else
379 		return IRQ_NONE;
380 }
381 
382 /*
383  * Configure/autoconfigure the port.
384  */
385 static void timbuart_config_port(struct uart_port *port, int flags)
386 {
387 	if (flags & UART_CONFIG_TYPE) {
388 		port->type = PORT_TIMBUART;
389 		timbuart_request_port(port);
390 	}
391 }
392 
393 static int timbuart_verify_port(struct uart_port *port,
394 	struct serial_struct *ser)
395 {
396 	/* we don't want the core code to modify any port params */
397 	return -EINVAL;
398 }
399 
400 static struct uart_ops timbuart_ops = {
401 	.tx_empty = timbuart_tx_empty,
402 	.set_mctrl = timbuart_set_mctrl,
403 	.get_mctrl = timbuart_get_mctrl,
404 	.stop_tx = timbuart_stop_tx,
405 	.start_tx = timbuart_start_tx,
406 	.flush_buffer = timbuart_flush_buffer,
407 	.stop_rx = timbuart_stop_rx,
408 	.enable_ms = timbuart_enable_ms,
409 	.break_ctl = timbuart_break_ctl,
410 	.startup = timbuart_startup,
411 	.shutdown = timbuart_shutdown,
412 	.set_termios = timbuart_set_termios,
413 	.type = timbuart_type,
414 	.release_port = timbuart_release_port,
415 	.request_port = timbuart_request_port,
416 	.config_port = timbuart_config_port,
417 	.verify_port = timbuart_verify_port
418 };
419 
420 static struct uart_driver timbuart_driver = {
421 	.owner = THIS_MODULE,
422 	.driver_name = "timberdale_uart",
423 	.dev_name = "ttyTU",
424 	.major = TIMBUART_MAJOR,
425 	.minor = TIMBUART_MINOR,
426 	.nr = 1
427 };
428 
429 static int timbuart_probe(struct platform_device *dev)
430 {
431 	int err, irq;
432 	struct timbuart_port *uart;
433 	struct resource *iomem;
434 
435 	dev_dbg(&dev->dev, "%s\n", __func__);
436 
437 	uart = kzalloc(sizeof(*uart), GFP_KERNEL);
438 	if (!uart) {
439 		err = -EINVAL;
440 		goto err_mem;
441 	}
442 
443 	uart->usedma = 0;
444 
445 	uart->port.uartclk = 3250000 * 16;
446 	uart->port.fifosize  = TIMBUART_FIFO_SIZE;
447 	uart->port.regshift  = 2;
448 	uart->port.iotype  = UPIO_MEM;
449 	uart->port.ops = &timbuart_ops;
450 	uart->port.irq = 0;
451 	uart->port.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP;
452 	uart->port.line  = 0;
453 	uart->port.dev	= &dev->dev;
454 
455 	iomem = platform_get_resource(dev, IORESOURCE_MEM, 0);
456 	if (!iomem) {
457 		err = -ENOMEM;
458 		goto err_register;
459 	}
460 	uart->port.mapbase = iomem->start;
461 	uart->port.membase = NULL;
462 
463 	irq = platform_get_irq(dev, 0);
464 	if (irq < 0) {
465 		err = -EINVAL;
466 		goto err_register;
467 	}
468 	uart->port.irq = irq;
469 
470 	tasklet_init(&uart->tasklet, timbuart_tasklet, (unsigned long)uart);
471 
472 	err = uart_register_driver(&timbuart_driver);
473 	if (err)
474 		goto err_register;
475 
476 	err = uart_add_one_port(&timbuart_driver, &uart->port);
477 	if (err)
478 		goto err_add_port;
479 
480 	platform_set_drvdata(dev, uart);
481 
482 	return 0;
483 
484 err_add_port:
485 	uart_unregister_driver(&timbuart_driver);
486 err_register:
487 	kfree(uart);
488 err_mem:
489 	printk(KERN_ERR "timberdale: Failed to register Timberdale UART: %d\n",
490 		err);
491 
492 	return err;
493 }
494 
495 static int timbuart_remove(struct platform_device *dev)
496 {
497 	struct timbuart_port *uart = platform_get_drvdata(dev);
498 
499 	tasklet_kill(&uart->tasklet);
500 	uart_remove_one_port(&timbuart_driver, &uart->port);
501 	uart_unregister_driver(&timbuart_driver);
502 	kfree(uart);
503 
504 	return 0;
505 }
506 
507 static struct platform_driver timbuart_platform_driver = {
508 	.driver = {
509 		.name	= "timb-uart",
510 		.owner	= THIS_MODULE,
511 	},
512 	.probe		= timbuart_probe,
513 	.remove		= timbuart_remove,
514 };
515 
516 module_platform_driver(timbuart_platform_driver);
517 
518 MODULE_DESCRIPTION("Timberdale UART driver");
519 MODULE_LICENSE("GPL v2");
520 MODULE_ALIAS("platform:timb-uart");
521 
522