xref: /linux/drivers/tty/serial/timbuart.c (revision 23c48a124b469cee2eb0c75e6d22d366d1caa118) 
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * timbuart.c timberdale FPGA UART driver
4  * Copyright (c) 2009 Intel Corporation
5  */
6 
7 /* Supports:
8  * Timberdale FPGA UART
9  */
10 
11 #include <linux/pci.h>
12 #include <linux/interrupt.h>
13 #include <linux/serial_core.h>
14 #include <linux/tty.h>
15 #include <linux/tty_flip.h>
16 #include <linux/kernel.h>
17 #include <linux/platform_device.h>
18 #include <linux/ioport.h>
19 #include <linux/slab.h>
20 #include <linux/module.h>
21 
22 #include "timbuart.h"
23 
24 struct timbuart_port {
25 	struct uart_port	port;
26 	struct tasklet_struct	tasklet;
27 	int			usedma;
28 	u32			last_ier;
29 	struct platform_device  *dev;
30 };
31 
32 static int baudrates[] = {9600, 19200, 38400, 57600, 115200, 230400, 460800,
33 	921600, 1843200, 3250000};
34 
35 static void timbuart_mctrl_check(struct uart_port *port, u32 isr, u32 *ier);
36 
37 static irqreturn_t timbuart_handleinterrupt(int irq, void *devid);
38 
39 static void timbuart_stop_rx(struct uart_port *port)
40 {
41 	/* spin lock held by upper layer, disable all RX interrupts */
42 	u32 ier = ioread32(port->membase + TIMBUART_IER) & ~RXFLAGS;
43 	iowrite32(ier, port->membase + TIMBUART_IER);
44 }
45 
46 static void timbuart_stop_tx(struct uart_port *port)
47 {
48 	/* spinlock held by upper layer, disable TX interrupt */
49 	u32 ier = ioread32(port->membase + TIMBUART_IER) & ~TXBAE;
50 	iowrite32(ier, port->membase + TIMBUART_IER);
51 }
52 
53 static void timbuart_start_tx(struct uart_port *port)
54 {
55 	struct timbuart_port *uart =
56 		container_of(port, struct timbuart_port, port);
57 
58 	/* do not transfer anything here -> fire off the tasklet */
59 	tasklet_schedule(&uart->tasklet);
60 }
61 
62 static unsigned int timbuart_tx_empty(struct uart_port *port)
63 {
64 	u32 isr = ioread32(port->membase + TIMBUART_ISR);
65 
66 	return (isr & TXBE) ? TIOCSER_TEMT : 0;
67 }
68 
69 static void timbuart_flush_buffer(struct uart_port *port)
70 {
71 	if (!timbuart_tx_empty(port)) {
72 		u8 ctl = ioread8(port->membase + TIMBUART_CTRL) |
73 			TIMBUART_CTRL_FLSHTX;
74 
75 		iowrite8(ctl, port->membase + TIMBUART_CTRL);
76 		iowrite32(TXBF, port->membase + TIMBUART_ISR);
77 	}
78 }
79 
80 static void timbuart_rx_chars(struct uart_port *port)
81 {
82 	struct tty_port *tport = &port->state->port;
83 
84 	while (ioread32(port->membase + TIMBUART_ISR) & RXDP) {
85 		u8 ch = ioread8(port->membase + TIMBUART_RXFIFO);
86 		port->icount.rx++;
87 		tty_insert_flip_char(tport, ch, TTY_NORMAL);
88 	}
89 
90 	tty_flip_buffer_push(tport);
91 
92 	dev_dbg(port->dev, "%s - total read %d bytes\n",
93 		__func__, port->icount.rx);
94 }
95 
96 static void timbuart_tx_chars(struct uart_port *port)
97 {
98 	struct circ_buf *xmit = &port->state->xmit;
99 
100 	while (!(ioread32(port->membase + TIMBUART_ISR) & TXBF) &&
101 		!uart_circ_empty(xmit)) {
102 		iowrite8(xmit->buf[xmit->tail],
103 			port->membase + TIMBUART_TXFIFO);
104 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
105 		port->icount.tx++;
106 	}
107 
108 	dev_dbg(port->dev,
109 		"%s - total written %d bytes, CTL: %x, RTS: %x, baud: %x\n",
110 		 __func__,
111 		port->icount.tx,
112 		ioread8(port->membase + TIMBUART_CTRL),
113 		port->mctrl & TIOCM_RTS,
114 		ioread8(port->membase + TIMBUART_BAUDRATE));
115 }
116 
117 static void timbuart_handle_tx_port(struct uart_port *port, u32 isr, u32 *ier)
118 {
119 	struct timbuart_port *uart =
120 		container_of(port, struct timbuart_port, port);
121 	struct circ_buf *xmit = &port->state->xmit;
122 
123 	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
124 		return;
125 
126 	if (port->x_char)
127 		return;
128 
129 	if (isr & TXFLAGS) {
130 		timbuart_tx_chars(port);
131 		/* clear all TX interrupts */
132 		iowrite32(TXFLAGS, port->membase + TIMBUART_ISR);
133 
134 		if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
135 			uart_write_wakeup(port);
136 	} else
137 		/* Re-enable any tx interrupt */
138 		*ier |= uart->last_ier & TXFLAGS;
139 
140 	/* enable interrupts if there are chars in the transmit buffer,
141 	 * Or if we delivered some bytes and want the almost empty interrupt
142 	 * we wake up the upper layer later when we got the interrupt
143 	 * to give it some time to go out...
144 	 */
145 	if (!uart_circ_empty(xmit))
146 		*ier |= TXBAE;
147 
148 	dev_dbg(port->dev, "%s - leaving\n", __func__);
149 }
150 
151 static void timbuart_handle_rx_port(struct uart_port *port, u32 isr, u32 *ier)
152 {
153 	if (isr & RXFLAGS) {
154 		/* Some RX status is set */
155 		if (isr & RXBF) {
156 			u8 ctl = ioread8(port->membase + TIMBUART_CTRL) |
157 				TIMBUART_CTRL_FLSHRX;
158 			iowrite8(ctl, port->membase + TIMBUART_CTRL);
159 			port->icount.overrun++;
160 		} else if (isr & (RXDP))
161 			timbuart_rx_chars(port);
162 
163 		/* ack all RX interrupts */
164 		iowrite32(RXFLAGS, port->membase + TIMBUART_ISR);
165 	}
166 
167 	/* always have the RX interrupts enabled */
168 	*ier |= RXBAF | RXBF | RXTT;
169 
170 	dev_dbg(port->dev, "%s - leaving\n", __func__);
171 }
172 
173 static void timbuart_tasklet(struct tasklet_struct *t)
174 {
175 	struct timbuart_port *uart = from_tasklet(uart, t, tasklet);
176 	u32 isr, ier = 0;
177 
178 	spin_lock(&uart->port.lock);
179 
180 	isr = ioread32(uart->port.membase + TIMBUART_ISR);
181 	dev_dbg(uart->port.dev, "%s ISR: %x\n", __func__, isr);
182 
183 	if (!uart->usedma)
184 		timbuart_handle_tx_port(&uart->port, isr, &ier);
185 
186 	timbuart_mctrl_check(&uart->port, isr, &ier);
187 
188 	if (!uart->usedma)
189 		timbuart_handle_rx_port(&uart->port, isr, &ier);
190 
191 	iowrite32(ier, uart->port.membase + TIMBUART_IER);
192 
193 	spin_unlock(&uart->port.lock);
194 	dev_dbg(uart->port.dev, "%s leaving\n", __func__);
195 }
196 
197 static unsigned int timbuart_get_mctrl(struct uart_port *port)
198 {
199 	u8 cts = ioread8(port->membase + TIMBUART_CTRL);
200 	dev_dbg(port->dev, "%s - cts %x\n", __func__, cts);
201 
202 	if (cts & TIMBUART_CTRL_CTS)
203 		return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
204 	else
205 		return TIOCM_DSR | TIOCM_CAR;
206 }
207 
208 static void timbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
209 {
210 	dev_dbg(port->dev, "%s - %x\n", __func__, mctrl);
211 
212 	if (mctrl & TIOCM_RTS)
213 		iowrite8(TIMBUART_CTRL_RTS, port->membase + TIMBUART_CTRL);
214 	else
215 		iowrite8(0, port->membase + TIMBUART_CTRL);
216 }
217 
218 static void timbuart_mctrl_check(struct uart_port *port, u32 isr, u32 *ier)
219 {
220 	unsigned int cts;
221 
222 	if (isr & CTS_DELTA) {
223 		/* ack */
224 		iowrite32(CTS_DELTA, port->membase + TIMBUART_ISR);
225 		cts = timbuart_get_mctrl(port);
226 		uart_handle_cts_change(port, cts & TIOCM_CTS);
227 		wake_up_interruptible(&port->state->port.delta_msr_wait);
228 	}
229 
230 	*ier |= CTS_DELTA;
231 }
232 
233 static void timbuart_break_ctl(struct uart_port *port, int ctl)
234 {
235 	/* N/A */
236 }
237 
238 static int timbuart_startup(struct uart_port *port)
239 {
240 	struct timbuart_port *uart =
241 		container_of(port, struct timbuart_port, port);
242 
243 	dev_dbg(port->dev, "%s\n", __func__);
244 
245 	iowrite8(TIMBUART_CTRL_FLSHRX, port->membase + TIMBUART_CTRL);
246 	iowrite32(0x1ff, port->membase + TIMBUART_ISR);
247 	/* Enable all but TX interrupts */
248 	iowrite32(RXBAF | RXBF | RXTT | CTS_DELTA,
249 		port->membase + TIMBUART_IER);
250 
251 	return request_irq(port->irq, timbuart_handleinterrupt, IRQF_SHARED,
252 		"timb-uart", uart);
253 }
254 
255 static void timbuart_shutdown(struct uart_port *port)
256 {
257 	struct timbuart_port *uart =
258 		container_of(port, struct timbuart_port, port);
259 	dev_dbg(port->dev, "%s\n", __func__);
260 	free_irq(port->irq, uart);
261 	iowrite32(0, port->membase + TIMBUART_IER);
262 
263 	timbuart_flush_buffer(port);
264 }
265 
266 static int get_bindex(int baud)
267 {
268 	int i;
269 
270 	for (i = 0; i < ARRAY_SIZE(baudrates); i++)
271 		if (baud <= baudrates[i])
272 			return i;
273 
274 	return -1;
275 }
276 
277 static void timbuart_set_termios(struct uart_port *port,
278 	struct ktermios *termios,
279 	struct ktermios *old)
280 {
281 	unsigned int baud;
282 	short bindex;
283 	unsigned long flags;
284 
285 	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
286 	bindex = get_bindex(baud);
287 	dev_dbg(port->dev, "%s - bindex %d\n", __func__, bindex);
288 
289 	if (bindex < 0)
290 		bindex = 0;
291 	baud = baudrates[bindex];
292 
293 	/* The serial layer calls into this once with old = NULL when setting
294 	   up initially */
295 	if (old)
296 		tty_termios_copy_hw(termios, old);
297 	tty_termios_encode_baud_rate(termios, baud, baud);
298 
299 	spin_lock_irqsave(&port->lock, flags);
300 	iowrite8((u8)bindex, port->membase + TIMBUART_BAUDRATE);
301 	uart_update_timeout(port, termios->c_cflag, baud);
302 	spin_unlock_irqrestore(&port->lock, flags);
303 }
304 
305 static const char *timbuart_type(struct uart_port *port)
306 {
307 	return port->type == PORT_UNKNOWN ? "timbuart" : NULL;
308 }
309 
310 /* We do not request/release mappings of the registers here,
311  * currently it's done in the proble function.
312  */
313 static void timbuart_release_port(struct uart_port *port)
314 {
315 	struct platform_device *pdev = to_platform_device(port->dev);
316 	int size =
317 		resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
318 
319 	if (port->flags & UPF_IOREMAP) {
320 		iounmap(port->membase);
321 		port->membase = NULL;
322 	}
323 
324 	release_mem_region(port->mapbase, size);
325 }
326 
327 static int timbuart_request_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 (!request_mem_region(port->mapbase, size, "timb-uart"))
334 		return -EBUSY;
335 
336 	if (port->flags & UPF_IOREMAP) {
337 		port->membase = ioremap(port->mapbase, size);
338 		if (port->membase == NULL) {
339 			release_mem_region(port->mapbase, size);
340 			return -ENOMEM;
341 		}
342 	}
343 
344 	return 0;
345 }
346 
347 static irqreturn_t timbuart_handleinterrupt(int irq, void *devid)
348 {
349 	struct timbuart_port *uart = (struct timbuart_port *)devid;
350 
351 	if (ioread8(uart->port.membase + TIMBUART_IPR)) {
352 		uart->last_ier = ioread32(uart->port.membase + TIMBUART_IER);
353 
354 		/* disable interrupts, the tasklet enables them again */
355 		iowrite32(0, uart->port.membase + TIMBUART_IER);
356 
357 		/* fire off bottom half */
358 		tasklet_schedule(&uart->tasklet);
359 
360 		return IRQ_HANDLED;
361 	} else
362 		return IRQ_NONE;
363 }
364 
365 /*
366  * Configure/autoconfigure the port.
367  */
368 static void timbuart_config_port(struct uart_port *port, int flags)
369 {
370 	if (flags & UART_CONFIG_TYPE) {
371 		port->type = PORT_TIMBUART;
372 		timbuart_request_port(port);
373 	}
374 }
375 
376 static int timbuart_verify_port(struct uart_port *port,
377 	struct serial_struct *ser)
378 {
379 	/* we don't want the core code to modify any port params */
380 	return -EINVAL;
381 }
382 
383 static const struct uart_ops timbuart_ops = {
384 	.tx_empty = timbuart_tx_empty,
385 	.set_mctrl = timbuart_set_mctrl,
386 	.get_mctrl = timbuart_get_mctrl,
387 	.stop_tx = timbuart_stop_tx,
388 	.start_tx = timbuart_start_tx,
389 	.flush_buffer = timbuart_flush_buffer,
390 	.stop_rx = timbuart_stop_rx,
391 	.break_ctl = timbuart_break_ctl,
392 	.startup = timbuart_startup,
393 	.shutdown = timbuart_shutdown,
394 	.set_termios = timbuart_set_termios,
395 	.type = timbuart_type,
396 	.release_port = timbuart_release_port,
397 	.request_port = timbuart_request_port,
398 	.config_port = timbuart_config_port,
399 	.verify_port = timbuart_verify_port
400 };
401 
402 static struct uart_driver timbuart_driver = {
403 	.owner = THIS_MODULE,
404 	.driver_name = "timberdale_uart",
405 	.dev_name = "ttyTU",
406 	.major = TIMBUART_MAJOR,
407 	.minor = TIMBUART_MINOR,
408 	.nr = 1
409 };
410 
411 static int timbuart_probe(struct platform_device *dev)
412 {
413 	int err, irq;
414 	struct timbuart_port *uart;
415 	struct resource *iomem;
416 
417 	dev_dbg(&dev->dev, "%s\n", __func__);
418 
419 	uart = kzalloc(sizeof(*uart), GFP_KERNEL);
420 	if (!uart) {
421 		err = -EINVAL;
422 		goto err_mem;
423 	}
424 
425 	uart->usedma = 0;
426 
427 	uart->port.uartclk = 3250000 * 16;
428 	uart->port.fifosize  = TIMBUART_FIFO_SIZE;
429 	uart->port.regshift  = 2;
430 	uart->port.iotype  = UPIO_MEM;
431 	uart->port.ops = &timbuart_ops;
432 	uart->port.irq = 0;
433 	uart->port.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP;
434 	uart->port.line  = 0;
435 	uart->port.dev	= &dev->dev;
436 
437 	iomem = platform_get_resource(dev, IORESOURCE_MEM, 0);
438 	if (!iomem) {
439 		err = -ENOMEM;
440 		goto err_register;
441 	}
442 	uart->port.mapbase = iomem->start;
443 	uart->port.membase = NULL;
444 
445 	irq = platform_get_irq(dev, 0);
446 	if (irq < 0) {
447 		err = -EINVAL;
448 		goto err_register;
449 	}
450 	uart->port.irq = irq;
451 
452 	tasklet_setup(&uart->tasklet, timbuart_tasklet);
453 
454 	err = uart_register_driver(&timbuart_driver);
455 	if (err)
456 		goto err_register;
457 
458 	err = uart_add_one_port(&timbuart_driver, &uart->port);
459 	if (err)
460 		goto err_add_port;
461 
462 	platform_set_drvdata(dev, uart);
463 
464 	return 0;
465 
466 err_add_port:
467 	uart_unregister_driver(&timbuart_driver);
468 err_register:
469 	kfree(uart);
470 err_mem:
471 	printk(KERN_ERR "timberdale: Failed to register Timberdale UART: %d\n",
472 		err);
473 
474 	return err;
475 }
476 
477 static int timbuart_remove(struct platform_device *dev)
478 {
479 	struct timbuart_port *uart = platform_get_drvdata(dev);
480 
481 	tasklet_kill(&uart->tasklet);
482 	uart_remove_one_port(&timbuart_driver, &uart->port);
483 	uart_unregister_driver(&timbuart_driver);
484 	kfree(uart);
485 
486 	return 0;
487 }
488 
489 static struct platform_driver timbuart_platform_driver = {
490 	.driver = {
491 		.name	= "timb-uart",
492 	},
493 	.probe		= timbuart_probe,
494 	.remove		= timbuart_remove,
495 };
496 
497 module_platform_driver(timbuart_platform_driver);
498 
499 MODULE_DESCRIPTION("Timberdale UART driver");
500 MODULE_LICENSE("GPL v2");
501 MODULE_ALIAS("platform:timb-uart");
502 
503