xref: /openbmc/linux/drivers/tty/serial/timbuart.c (revision bc5aa3a0) 
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_break_ctl(struct uart_port *port, int ctl)
248 {
249 	/* N/A */
250 }
251 
252 static int timbuart_startup(struct uart_port *port)
253 {
254 	struct timbuart_port *uart =
255 		container_of(port, struct timbuart_port, port);
256 
257 	dev_dbg(port->dev, "%s\n", __func__);
258 
259 	iowrite8(TIMBUART_CTRL_FLSHRX, port->membase + TIMBUART_CTRL);
260 	iowrite32(0x1ff, port->membase + TIMBUART_ISR);
261 	/* Enable all but TX interrupts */
262 	iowrite32(RXBAF | RXBF | RXTT | CTS_DELTA,
263 		port->membase + TIMBUART_IER);
264 
265 	return request_irq(port->irq, timbuart_handleinterrupt, IRQF_SHARED,
266 		"timb-uart", uart);
267 }
268 
269 static void timbuart_shutdown(struct uart_port *port)
270 {
271 	struct timbuart_port *uart =
272 		container_of(port, struct timbuart_port, port);
273 	dev_dbg(port->dev, "%s\n", __func__);
274 	free_irq(port->irq, uart);
275 	iowrite32(0, port->membase + TIMBUART_IER);
276 
277 	timbuart_flush_buffer(port);
278 }
279 
280 static int get_bindex(int baud)
281 {
282 	int i;
283 
284 	for (i = 0; i < ARRAY_SIZE(baudrates); i++)
285 		if (baud <= baudrates[i])
286 			return i;
287 
288 	return -1;
289 }
290 
291 static void timbuart_set_termios(struct uart_port *port,
292 	struct ktermios *termios,
293 	struct ktermios *old)
294 {
295 	unsigned int baud;
296 	short bindex;
297 	unsigned long flags;
298 
299 	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
300 	bindex = get_bindex(baud);
301 	dev_dbg(port->dev, "%s - bindex %d\n", __func__, bindex);
302 
303 	if (bindex < 0)
304 		bindex = 0;
305 	baud = baudrates[bindex];
306 
307 	/* The serial layer calls into this once with old = NULL when setting
308 	   up initially */
309 	if (old)
310 		tty_termios_copy_hw(termios, old);
311 	tty_termios_encode_baud_rate(termios, baud, baud);
312 
313 	spin_lock_irqsave(&port->lock, flags);
314 	iowrite8((u8)bindex, port->membase + TIMBUART_BAUDRATE);
315 	uart_update_timeout(port, termios->c_cflag, baud);
316 	spin_unlock_irqrestore(&port->lock, flags);
317 }
318 
319 static const char *timbuart_type(struct uart_port *port)
320 {
321 	return port->type == PORT_UNKNOWN ? "timbuart" : NULL;
322 }
323 
324 /* We do not request/release mappings of the registers here,
325  * currently it's done in the proble function.
326  */
327 static void timbuart_release_port(struct uart_port *port)
328 {
329 	struct platform_device *pdev = to_platform_device(port->dev);
330 	int size =
331 		resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
332 
333 	if (port->flags & UPF_IOREMAP) {
334 		iounmap(port->membase);
335 		port->membase = NULL;
336 	}
337 
338 	release_mem_region(port->mapbase, size);
339 }
340 
341 static int timbuart_request_port(struct uart_port *port)
342 {
343 	struct platform_device *pdev = to_platform_device(port->dev);
344 	int size =
345 		resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
346 
347 	if (!request_mem_region(port->mapbase, size, "timb-uart"))
348 		return -EBUSY;
349 
350 	if (port->flags & UPF_IOREMAP) {
351 		port->membase = ioremap(port->mapbase, size);
352 		if (port->membase == NULL) {
353 			release_mem_region(port->mapbase, size);
354 			return -ENOMEM;
355 		}
356 	}
357 
358 	return 0;
359 }
360 
361 static irqreturn_t timbuart_handleinterrupt(int irq, void *devid)
362 {
363 	struct timbuart_port *uart = (struct timbuart_port *)devid;
364 
365 	if (ioread8(uart->port.membase + TIMBUART_IPR)) {
366 		uart->last_ier = ioread32(uart->port.membase + TIMBUART_IER);
367 
368 		/* disable interrupts, the tasklet enables them again */
369 		iowrite32(0, uart->port.membase + TIMBUART_IER);
370 
371 		/* fire off bottom half */
372 		tasklet_schedule(&uart->tasklet);
373 
374 		return IRQ_HANDLED;
375 	} else
376 		return IRQ_NONE;
377 }
378 
379 /*
380  * Configure/autoconfigure the port.
381  */
382 static void timbuart_config_port(struct uart_port *port, int flags)
383 {
384 	if (flags & UART_CONFIG_TYPE) {
385 		port->type = PORT_TIMBUART;
386 		timbuart_request_port(port);
387 	}
388 }
389 
390 static int timbuart_verify_port(struct uart_port *port,
391 	struct serial_struct *ser)
392 {
393 	/* we don't want the core code to modify any port params */
394 	return -EINVAL;
395 }
396 
397 static struct uart_ops timbuart_ops = {
398 	.tx_empty = timbuart_tx_empty,
399 	.set_mctrl = timbuart_set_mctrl,
400 	.get_mctrl = timbuart_get_mctrl,
401 	.stop_tx = timbuart_stop_tx,
402 	.start_tx = timbuart_start_tx,
403 	.flush_buffer = timbuart_flush_buffer,
404 	.stop_rx = timbuart_stop_rx,
405 	.break_ctl = timbuart_break_ctl,
406 	.startup = timbuart_startup,
407 	.shutdown = timbuart_shutdown,
408 	.set_termios = timbuart_set_termios,
409 	.type = timbuart_type,
410 	.release_port = timbuart_release_port,
411 	.request_port = timbuart_request_port,
412 	.config_port = timbuart_config_port,
413 	.verify_port = timbuart_verify_port
414 };
415 
416 static struct uart_driver timbuart_driver = {
417 	.owner = THIS_MODULE,
418 	.driver_name = "timberdale_uart",
419 	.dev_name = "ttyTU",
420 	.major = TIMBUART_MAJOR,
421 	.minor = TIMBUART_MINOR,
422 	.nr = 1
423 };
424 
425 static int timbuart_probe(struct platform_device *dev)
426 {
427 	int err, irq;
428 	struct timbuart_port *uart;
429 	struct resource *iomem;
430 
431 	dev_dbg(&dev->dev, "%s\n", __func__);
432 
433 	uart = kzalloc(sizeof(*uart), GFP_KERNEL);
434 	if (!uart) {
435 		err = -EINVAL;
436 		goto err_mem;
437 	}
438 
439 	uart->usedma = 0;
440 
441 	uart->port.uartclk = 3250000 * 16;
442 	uart->port.fifosize  = TIMBUART_FIFO_SIZE;
443 	uart->port.regshift  = 2;
444 	uart->port.iotype  = UPIO_MEM;
445 	uart->port.ops = &timbuart_ops;
446 	uart->port.irq = 0;
447 	uart->port.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP;
448 	uart->port.line  = 0;
449 	uart->port.dev	= &dev->dev;
450 
451 	iomem = platform_get_resource(dev, IORESOURCE_MEM, 0);
452 	if (!iomem) {
453 		err = -ENOMEM;
454 		goto err_register;
455 	}
456 	uart->port.mapbase = iomem->start;
457 	uart->port.membase = NULL;
458 
459 	irq = platform_get_irq(dev, 0);
460 	if (irq < 0) {
461 		err = -EINVAL;
462 		goto err_register;
463 	}
464 	uart->port.irq = irq;
465 
466 	tasklet_init(&uart->tasklet, timbuart_tasklet, (unsigned long)uart);
467 
468 	err = uart_register_driver(&timbuart_driver);
469 	if (err)
470 		goto err_register;
471 
472 	err = uart_add_one_port(&timbuart_driver, &uart->port);
473 	if (err)
474 		goto err_add_port;
475 
476 	platform_set_drvdata(dev, uart);
477 
478 	return 0;
479 
480 err_add_port:
481 	uart_unregister_driver(&timbuart_driver);
482 err_register:
483 	kfree(uart);
484 err_mem:
485 	printk(KERN_ERR "timberdale: Failed to register Timberdale UART: %d\n",
486 		err);
487 
488 	return err;
489 }
490 
491 static int timbuart_remove(struct platform_device *dev)
492 {
493 	struct timbuart_port *uart = platform_get_drvdata(dev);
494 
495 	tasklet_kill(&uart->tasklet);
496 	uart_remove_one_port(&timbuart_driver, &uart->port);
497 	uart_unregister_driver(&timbuart_driver);
498 	kfree(uart);
499 
500 	return 0;
501 }
502 
503 static struct platform_driver timbuart_platform_driver = {
504 	.driver = {
505 		.name	= "timb-uart",
506 	},
507 	.probe		= timbuart_probe,
508 	.remove		= timbuart_remove,
509 };
510 
511 module_platform_driver(timbuart_platform_driver);
512 
513 MODULE_DESCRIPTION("Timberdale UART driver");
514 MODULE_LICENSE("GPL v2");
515 MODULE_ALIAS("platform:timb-uart");
516 
517