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
36struct 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
44static int baudrates[] = {9600, 19200, 38400, 57600, 115200, 230400, 460800,
45	921600, 1843200, 3250000};
46
47static void timbuart_mctrl_check(struct uart_port *port, u32 isr, u32 *ier);
48
49static irqreturn_t timbuart_handleinterrupt(int irq, void *devid);
50
51static 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
58static 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
65static 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
74static 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
81static 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
92static 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
110static 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
131static 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
165static 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
187static 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
211static 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
222static 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
232static 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
247static void timbuart_break_ctl(struct uart_port *port, int ctl)
248{
249	/* N/A */
250}
251
252static 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
269static 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
278static int get_bindex(int baud)
279{
280	int i;
281
282	for (i = 0; i < ARRAY_SIZE(baudrates); i++)
283		if (baud <= baudrates[i])
284			return i;
285
286	return -1;
287}
288
289static void timbuart_set_termios(struct uart_port *port,
290	struct ktermios *termios,
291	struct ktermios *old)
292{
293	unsigned int baud;
294	short bindex;
295	unsigned long flags;
296
297	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
298	bindex = get_bindex(baud);
299	dev_dbg(port->dev, "%s - bindex %d\n", __func__, bindex);
300
301	if (bindex < 0)
302		bindex = 0;
303	baud = baudrates[bindex];
304
305	/* The serial layer calls into this once with old = NULL when setting
306	   up initially */
307	if (old)
308		tty_termios_copy_hw(termios, old);
309	tty_termios_encode_baud_rate(termios, baud, baud);
310
311	spin_lock_irqsave(&port->lock, flags);
312	iowrite8((u8)bindex, port->membase + TIMBUART_BAUDRATE);
313	uart_update_timeout(port, termios->c_cflag, baud);
314	spin_unlock_irqrestore(&port->lock, flags);
315}
316
317static const char *timbuart_type(struct uart_port *port)
318{
319	return port->type == PORT_UNKNOWN ? "timbuart" : NULL;
320}
321
322/* We do not request/release mappings of the registers here,
323 * currently it's done in the proble function.
324 */
325static void timbuart_release_port(struct uart_port *port)
326{
327	struct platform_device *pdev = to_platform_device(port->dev);
328	int size =
329		resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
330
331	if (port->flags & UPF_IOREMAP) {
332		iounmap(port->membase);
333		port->membase = NULL;
334	}
335
336	release_mem_region(port->mapbase, size);
337}
338
339static int timbuart_request_port(struct uart_port *port)
340{
341	struct platform_device *pdev = to_platform_device(port->dev);
342	int size =
343		resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
344
345	if (!request_mem_region(port->mapbase, size, "timb-uart"))
346		return -EBUSY;
347
348	if (port->flags & UPF_IOREMAP) {
349		port->membase = ioremap(port->mapbase, size);
350		if (port->membase == NULL) {
351			release_mem_region(port->mapbase, size);
352			return -ENOMEM;
353		}
354	}
355
356	return 0;
357}
358
359static irqreturn_t timbuart_handleinterrupt(int irq, void *devid)
360{
361	struct timbuart_port *uart = (struct timbuart_port *)devid;
362
363	if (ioread8(uart->port.membase + TIMBUART_IPR)) {
364		uart->last_ier = ioread32(uart->port.membase + TIMBUART_IER);
365
366		/* disable interrupts, the tasklet enables them again */
367		iowrite32(0, uart->port.membase + TIMBUART_IER);
368
369		/* fire off bottom half */
370		tasklet_schedule(&uart->tasklet);
371
372		return IRQ_HANDLED;
373	} else
374		return IRQ_NONE;
375}
376
377/*
378 * Configure/autoconfigure the port.
379 */
380static void timbuart_config_port(struct uart_port *port, int flags)
381{
382	if (flags & UART_CONFIG_TYPE) {
383		port->type = PORT_TIMBUART;
384		timbuart_request_port(port);
385	}
386}
387
388static int timbuart_verify_port(struct uart_port *port,
389	struct serial_struct *ser)
390{
391	/* we don't want the core code to modify any port params */
392	return -EINVAL;
393}
394
395static struct uart_ops timbuart_ops = {
396	.tx_empty = timbuart_tx_empty,
397	.set_mctrl = timbuart_set_mctrl,
398	.get_mctrl = timbuart_get_mctrl,
399	.stop_tx = timbuart_stop_tx,
400	.start_tx = timbuart_start_tx,
401	.flush_buffer = timbuart_flush_buffer,
402	.stop_rx = timbuart_stop_rx,
403	.break_ctl = timbuart_break_ctl,
404	.startup = timbuart_startup,
405	.shutdown = timbuart_shutdown,
406	.set_termios = timbuart_set_termios,
407	.type = timbuart_type,
408	.release_port = timbuart_release_port,
409	.request_port = timbuart_request_port,
410	.config_port = timbuart_config_port,
411	.verify_port = timbuart_verify_port
412};
413
414static struct uart_driver timbuart_driver = {
415	.owner = THIS_MODULE,
416	.driver_name = "timberdale_uart",
417	.dev_name = "ttyTU",
418	.major = TIMBUART_MAJOR,
419	.minor = TIMBUART_MINOR,
420	.nr = 1
421};
422
423static int timbuart_probe(struct platform_device *dev)
424{
425	int err, irq;
426	struct timbuart_port *uart;
427	struct resource *iomem;
428
429	dev_dbg(&dev->dev, "%s\n", __func__);
430
431	uart = kzalloc(sizeof(*uart), GFP_KERNEL);
432	if (!uart) {
433		err = -EINVAL;
434		goto err_mem;
435	}
436
437	uart->usedma = 0;
438
439	uart->port.uartclk = 3250000 * 16;
440	uart->port.fifosize  = TIMBUART_FIFO_SIZE;
441	uart->port.regshift  = 2;
442	uart->port.iotype  = UPIO_MEM;
443	uart->port.ops = &timbuart_ops;
444	uart->port.irq = 0;
445	uart->port.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP;
446	uart->port.line  = 0;
447	uart->port.dev	= &dev->dev;
448
449	iomem = platform_get_resource(dev, IORESOURCE_MEM, 0);
450	if (!iomem) {
451		err = -ENOMEM;
452		goto err_register;
453	}
454	uart->port.mapbase = iomem->start;
455	uart->port.membase = NULL;
456
457	irq = platform_get_irq(dev, 0);
458	if (irq < 0) {
459		err = -EINVAL;
460		goto err_register;
461	}
462	uart->port.irq = irq;
463
464	tasklet_init(&uart->tasklet, timbuart_tasklet, (unsigned long)uart);
465
466	err = uart_register_driver(&timbuart_driver);
467	if (err)
468		goto err_register;
469
470	err = uart_add_one_port(&timbuart_driver, &uart->port);
471	if (err)
472		goto err_add_port;
473
474	platform_set_drvdata(dev, uart);
475
476	return 0;
477
478err_add_port:
479	uart_unregister_driver(&timbuart_driver);
480err_register:
481	kfree(uart);
482err_mem:
483	printk(KERN_ERR "timberdale: Failed to register Timberdale UART: %d\n",
484		err);
485
486	return err;
487}
488
489static int timbuart_remove(struct platform_device *dev)
490{
491	struct timbuart_port *uart = platform_get_drvdata(dev);
492
493	tasklet_kill(&uart->tasklet);
494	uart_remove_one_port(&timbuart_driver, &uart->port);
495	uart_unregister_driver(&timbuart_driver);
496	kfree(uart);
497
498	return 0;
499}
500
501static struct platform_driver timbuart_platform_driver = {
502	.driver = {
503		.name	= "timb-uart",
504		.owner	= THIS_MODULE,
505	},
506	.probe		= timbuart_probe,
507	.remove		= timbuart_remove,
508};
509
510module_platform_driver(timbuart_platform_driver);
511
512MODULE_DESCRIPTION("Timberdale UART driver");
513MODULE_LICENSE("GPL v2");
514MODULE_ALIAS("platform:timb-uart");
515
516