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Harini Katakam58bf0162014-08-22 14:58:01 +05301/*
2 * Cadence WDT driver - Used by Xilinx Zynq
3 *
4 * Copyright (C) 2010 - 2014 Xilinx, Inc.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/clk.h>
13#include <linux/init.h>
14#include <linux/interrupt.h>
15#include <linux/io.h>
16#include <linux/irq.h>
17#include <linux/kernel.h>
18#include <linux/module.h>
19#include <linux/of.h>
20#include <linux/platform_device.h>
Harini Katakam58bf0162014-08-22 14:58:01 +053021#include <linux/watchdog.h>
22
23#define CDNS_WDT_DEFAULT_TIMEOUT 10
24/* Supports 1 - 516 sec */
25#define CDNS_WDT_MIN_TIMEOUT 1
26#define CDNS_WDT_MAX_TIMEOUT 516
27
28/* Restart key */
29#define CDNS_WDT_RESTART_KEY 0x00001999
30
31/* Counter register access key */
32#define CDNS_WDT_REGISTER_ACCESS_KEY 0x00920000
33
34/* Counter value divisor */
35#define CDNS_WDT_COUNTER_VALUE_DIVISOR 0x1000
36
37/* Clock prescaler value and selection */
38#define CDNS_WDT_PRESCALE_64 64
39#define CDNS_WDT_PRESCALE_512 512
40#define CDNS_WDT_PRESCALE_4096 4096
41#define CDNS_WDT_PRESCALE_SELECT_64 1
42#define CDNS_WDT_PRESCALE_SELECT_512 2
43#define CDNS_WDT_PRESCALE_SELECT_4096 3
44
45/* Input clock frequency */
46#define CDNS_WDT_CLK_10MHZ 10000000
47#define CDNS_WDT_CLK_75MHZ 75000000
48
49/* Counter maximum value */
50#define CDNS_WDT_COUNTER_MAX 0xFFF
51
52static int wdt_timeout = CDNS_WDT_DEFAULT_TIMEOUT;
53static int nowayout = WATCHDOG_NOWAYOUT;
54
55module_param(wdt_timeout, int, 0);
56MODULE_PARM_DESC(wdt_timeout,
57 "Watchdog time in seconds. (default="
58 __MODULE_STRING(CDNS_WDT_DEFAULT_TIMEOUT) ")");
59
60module_param(nowayout, int, 0);
61MODULE_PARM_DESC(nowayout,
62 "Watchdog cannot be stopped once started (default="
63 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
64
65/**
66 * struct cdns_wdt - Watchdog device structure
67 * @regs: baseaddress of device
68 * @rst: reset flag
69 * @clk: struct clk * of a clock source
70 * @prescaler: for saving prescaler value
71 * @ctrl_clksel: counter clock prescaler selection
72 * @io_lock: spinlock for IO register access
73 * @cdns_wdt_device: watchdog device structure
Harini Katakam58bf0162014-08-22 14:58:01 +053074 *
75 * Structure containing parameters specific to cadence watchdog.
76 */
77struct cdns_wdt {
78 void __iomem *regs;
79 bool rst;
80 struct clk *clk;
81 u32 prescaler;
82 u32 ctrl_clksel;
83 spinlock_t io_lock;
84 struct watchdog_device cdns_wdt_device;
Harini Katakam58bf0162014-08-22 14:58:01 +053085};
86
87/* Write access to Registers */
88static inline void cdns_wdt_writereg(struct cdns_wdt *wdt, u32 offset, u32 val)
89{
90 writel_relaxed(val, wdt->regs + offset);
91}
92
93/*************************Register Map**************************************/
94
95/* Register Offsets for the WDT */
96#define CDNS_WDT_ZMR_OFFSET 0x0 /* Zero Mode Register */
97#define CDNS_WDT_CCR_OFFSET 0x4 /* Counter Control Register */
98#define CDNS_WDT_RESTART_OFFSET 0x8 /* Restart Register */
99#define CDNS_WDT_SR_OFFSET 0xC /* Status Register */
100
101/*
102 * Zero Mode Register - This register controls how the time out is indicated
103 * and also contains the access code to allow writes to the register (0xABC).
104 */
105#define CDNS_WDT_ZMR_WDEN_MASK 0x00000001 /* Enable the WDT */
106#define CDNS_WDT_ZMR_RSTEN_MASK 0x00000002 /* Enable the reset output */
107#define CDNS_WDT_ZMR_IRQEN_MASK 0x00000004 /* Enable IRQ output */
108#define CDNS_WDT_ZMR_RSTLEN_16 0x00000030 /* Reset pulse of 16 pclk cycles */
109#define CDNS_WDT_ZMR_ZKEY_VAL 0x00ABC000 /* Access key, 0xABC << 12 */
110/*
111 * Counter Control register - This register controls how fast the timer runs
112 * and the reset value and also contains the access code to allow writes to
113 * the register.
114 */
115#define CDNS_WDT_CCR_CRV_MASK 0x00003FFC /* Counter reset value */
116
117/**
118 * cdns_wdt_stop - Stop the watchdog.
119 *
120 * @wdd: watchdog device
121 *
122 * Read the contents of the ZMR register, clear the WDEN bit
123 * in the register and set the access key for successful write.
124 *
125 * Return: always 0
126 */
127static int cdns_wdt_stop(struct watchdog_device *wdd)
128{
129 struct cdns_wdt *wdt = watchdog_get_drvdata(wdd);
130
131 spin_lock(&wdt->io_lock);
132 cdns_wdt_writereg(wdt, CDNS_WDT_ZMR_OFFSET,
133 CDNS_WDT_ZMR_ZKEY_VAL & (~CDNS_WDT_ZMR_WDEN_MASK));
134 spin_unlock(&wdt->io_lock);
135
136 return 0;
137}
138
139/**
140 * cdns_wdt_reload - Reload the watchdog timer (i.e. pat the watchdog).
141 *
142 * @wdd: watchdog device
143 *
144 * Write the restart key value (0x00001999) to the restart register.
145 *
146 * Return: always 0
147 */
148static int cdns_wdt_reload(struct watchdog_device *wdd)
149{
150 struct cdns_wdt *wdt = watchdog_get_drvdata(wdd);
151
152 spin_lock(&wdt->io_lock);
153 cdns_wdt_writereg(wdt, CDNS_WDT_RESTART_OFFSET,
154 CDNS_WDT_RESTART_KEY);
155 spin_unlock(&wdt->io_lock);
156
157 return 0;
158}
159
160/**
161 * cdns_wdt_start - Enable and start the watchdog.
162 *
163 * @wdd: watchdog device
164 *
165 * The counter value is calculated according to the formula:
166 * calculated count = (timeout * clock) / prescaler + 1.
167 * The calculated count is divided by 0x1000 to obtain the field value
168 * to write to counter control register.
169 * Clears the contents of prescaler and counter reset value. Sets the
170 * prescaler to 4096 and the calculated count and access key
171 * to write to CCR Register.
172 * Sets the WDT (WDEN bit) and either the Reset signal(RSTEN bit)
173 * or Interrupt signal(IRQEN) with a specified cycles and the access
174 * key to write to ZMR Register.
175 *
176 * Return: always 0
177 */
178static int cdns_wdt_start(struct watchdog_device *wdd)
179{
180 struct cdns_wdt *wdt = watchdog_get_drvdata(wdd);
181 unsigned int data = 0;
182 unsigned short count;
183 unsigned long clock_f = clk_get_rate(wdt->clk);
184
185 /*
186 * Counter value divisor to obtain the value of
187 * counter reset to be written to control register.
188 */
189 count = (wdd->timeout * (clock_f / wdt->prescaler)) /
190 CDNS_WDT_COUNTER_VALUE_DIVISOR + 1;
191
192 if (count > CDNS_WDT_COUNTER_MAX)
193 count = CDNS_WDT_COUNTER_MAX;
194
195 spin_lock(&wdt->io_lock);
196 cdns_wdt_writereg(wdt, CDNS_WDT_ZMR_OFFSET,
197 CDNS_WDT_ZMR_ZKEY_VAL);
198
199 count = (count << 2) & CDNS_WDT_CCR_CRV_MASK;
200
201 /* Write counter access key first to be able write to register */
202 data = count | CDNS_WDT_REGISTER_ACCESS_KEY | wdt->ctrl_clksel;
203 cdns_wdt_writereg(wdt, CDNS_WDT_CCR_OFFSET, data);
204 data = CDNS_WDT_ZMR_WDEN_MASK | CDNS_WDT_ZMR_RSTLEN_16 |
205 CDNS_WDT_ZMR_ZKEY_VAL;
206
207 /* Reset on timeout if specified in device tree. */
208 if (wdt->rst) {
209 data |= CDNS_WDT_ZMR_RSTEN_MASK;
210 data &= ~CDNS_WDT_ZMR_IRQEN_MASK;
211 } else {
212 data &= ~CDNS_WDT_ZMR_RSTEN_MASK;
213 data |= CDNS_WDT_ZMR_IRQEN_MASK;
214 }
215 cdns_wdt_writereg(wdt, CDNS_WDT_ZMR_OFFSET, data);
216 cdns_wdt_writereg(wdt, CDNS_WDT_RESTART_OFFSET,
217 CDNS_WDT_RESTART_KEY);
218 spin_unlock(&wdt->io_lock);
219
220 return 0;
221}
222
223/**
224 * cdns_wdt_settimeout - Set a new timeout value for the watchdog device.
225 *
226 * @wdd: watchdog device
227 * @new_time: new timeout value that needs to be set
228 * Return: 0 on success
229 *
230 * Update the watchdog_device timeout with new value which is used when
231 * cdns_wdt_start is called.
232 */
233static int cdns_wdt_settimeout(struct watchdog_device *wdd,
234 unsigned int new_time)
235{
236 wdd->timeout = new_time;
237
238 return cdns_wdt_start(wdd);
239}
240
241/**
242 * cdns_wdt_irq_handler - Notifies of watchdog timeout.
243 *
244 * @irq: interrupt number
245 * @dev_id: pointer to a platform device structure
246 * Return: IRQ_HANDLED
247 *
248 * The handler is invoked when the watchdog times out and a
249 * reset on timeout has not been enabled.
250 */
251static irqreturn_t cdns_wdt_irq_handler(int irq, void *dev_id)
252{
253 struct platform_device *pdev = dev_id;
254
255 dev_info(&pdev->dev,
256 "Watchdog timed out. Internal reset not enabled\n");
257
258 return IRQ_HANDLED;
259}
260
261/*
262 * Info structure used to indicate the features supported by the device
263 * to the upper layers. This is defined in watchdog.h header file.
264 */
265static struct watchdog_info cdns_wdt_info = {
266 .identity = "cdns_wdt watchdog",
267 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
268 WDIOF_MAGICCLOSE,
269};
270
271/* Watchdog Core Ops */
272static struct watchdog_ops cdns_wdt_ops = {
273 .owner = THIS_MODULE,
274 .start = cdns_wdt_start,
275 .stop = cdns_wdt_stop,
276 .ping = cdns_wdt_reload,
277 .set_timeout = cdns_wdt_settimeout,
278};
279
Harini Katakam58bf0162014-08-22 14:58:01 +0530280/************************Platform Operations*****************************/
281/**
282 * cdns_wdt_probe - Probe call for the device.
283 *
284 * @pdev: handle to the platform device structure.
285 * Return: 0 on success, negative error otherwise.
286 *
287 * It does all the memory allocation and registration for the device.
288 */
289static int cdns_wdt_probe(struct platform_device *pdev)
290{
291 struct resource *res;
292 int ret, irq;
293 unsigned long clock_f;
294 struct cdns_wdt *wdt;
295 struct watchdog_device *cdns_wdt_device;
296
297 wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
298 if (!wdt)
299 return -ENOMEM;
300
301 cdns_wdt_device = &wdt->cdns_wdt_device;
302 cdns_wdt_device->info = &cdns_wdt_info;
303 cdns_wdt_device->ops = &cdns_wdt_ops;
304 cdns_wdt_device->timeout = CDNS_WDT_DEFAULT_TIMEOUT;
305 cdns_wdt_device->min_timeout = CDNS_WDT_MIN_TIMEOUT;
306 cdns_wdt_device->max_timeout = CDNS_WDT_MAX_TIMEOUT;
307
308 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
309 wdt->regs = devm_ioremap_resource(&pdev->dev, res);
310 if (IS_ERR(wdt->regs))
311 return PTR_ERR(wdt->regs);
312
313 /* Register the interrupt */
314 wdt->rst = of_property_read_bool(pdev->dev.of_node, "reset-on-timeout");
315 irq = platform_get_irq(pdev, 0);
316 if (!wdt->rst && irq >= 0) {
317 ret = devm_request_irq(&pdev->dev, irq, cdns_wdt_irq_handler, 0,
318 pdev->name, pdev);
319 if (ret) {
320 dev_err(&pdev->dev,
321 "cannot register interrupt handler err=%d\n",
322 ret);
323 return ret;
324 }
325 }
326
327 /* Initialize the members of cdns_wdt structure */
328 cdns_wdt_device->parent = &pdev->dev;
329
330 ret = watchdog_init_timeout(cdns_wdt_device, wdt_timeout, &pdev->dev);
331 if (ret) {
332 dev_err(&pdev->dev, "unable to set timeout value\n");
333 return ret;
334 }
335
336 watchdog_set_nowayout(cdns_wdt_device, nowayout);
Damien Riegel5e1f9762015-11-20 16:54:53 -0500337 watchdog_stop_on_reboot(cdns_wdt_device);
Harini Katakam58bf0162014-08-22 14:58:01 +0530338 watchdog_set_drvdata(cdns_wdt_device, wdt);
339
340 wdt->clk = devm_clk_get(&pdev->dev, NULL);
341 if (IS_ERR(wdt->clk)) {
342 dev_err(&pdev->dev, "input clock not found\n");
343 ret = PTR_ERR(wdt->clk);
344 return ret;
345 }
346
347 ret = clk_prepare_enable(wdt->clk);
348 if (ret) {
349 dev_err(&pdev->dev, "unable to enable clock\n");
350 return ret;
351 }
352
353 clock_f = clk_get_rate(wdt->clk);
354 if (clock_f <= CDNS_WDT_CLK_75MHZ) {
355 wdt->prescaler = CDNS_WDT_PRESCALE_512;
356 wdt->ctrl_clksel = CDNS_WDT_PRESCALE_SELECT_512;
357 } else {
358 wdt->prescaler = CDNS_WDT_PRESCALE_4096;
359 wdt->ctrl_clksel = CDNS_WDT_PRESCALE_SELECT_4096;
360 }
361
362 spin_lock_init(&wdt->io_lock);
363
Harini Katakam58bf0162014-08-22 14:58:01 +0530364 ret = watchdog_register_device(cdns_wdt_device);
365 if (ret) {
366 dev_err(&pdev->dev, "Failed to register wdt device\n");
367 goto err_clk_disable;
368 }
369 platform_set_drvdata(pdev, wdt);
370
371 dev_dbg(&pdev->dev, "Xilinx Watchdog Timer at %p with timeout %ds%s\n",
372 wdt->regs, cdns_wdt_device->timeout,
373 nowayout ? ", nowayout" : "");
374
375 return 0;
376
377err_clk_disable:
378 clk_disable_unprepare(wdt->clk);
379
380 return ret;
381}
382
383/**
384 * cdns_wdt_remove - Probe call for the device.
385 *
386 * @pdev: handle to the platform device structure.
387 * Return: 0 on success, otherwise negative error.
388 *
389 * Unregister the device after releasing the resources.
390 */
391static int cdns_wdt_remove(struct platform_device *pdev)
392{
393 struct cdns_wdt *wdt = platform_get_drvdata(pdev);
394
395 cdns_wdt_stop(&wdt->cdns_wdt_device);
396 watchdog_unregister_device(&wdt->cdns_wdt_device);
Harini Katakam58bf0162014-08-22 14:58:01 +0530397 clk_disable_unprepare(wdt->clk);
398
399 return 0;
400}
401
402/**
403 * cdns_wdt_shutdown - Stop the device.
404 *
405 * @pdev: handle to the platform structure.
406 *
407 */
408static void cdns_wdt_shutdown(struct platform_device *pdev)
409{
410 struct cdns_wdt *wdt = platform_get_drvdata(pdev);
411
412 cdns_wdt_stop(&wdt->cdns_wdt_device);
413 clk_disable_unprepare(wdt->clk);
414}
415
416/**
417 * cdns_wdt_suspend - Stop the device.
418 *
419 * @dev: handle to the device structure.
420 * Return: 0 always.
421 */
422static int __maybe_unused cdns_wdt_suspend(struct device *dev)
423{
Geliang Tang62e21f52015-12-27 21:15:47 +0800424 struct platform_device *pdev = to_platform_device(dev);
Harini Katakam58bf0162014-08-22 14:58:01 +0530425 struct cdns_wdt *wdt = platform_get_drvdata(pdev);
426
427 cdns_wdt_stop(&wdt->cdns_wdt_device);
428 clk_disable_unprepare(wdt->clk);
429
430 return 0;
431}
432
433/**
434 * cdns_wdt_resume - Resume the device.
435 *
436 * @dev: handle to the device structure.
437 * Return: 0 on success, errno otherwise.
438 */
439static int __maybe_unused cdns_wdt_resume(struct device *dev)
440{
441 int ret;
Geliang Tang62e21f52015-12-27 21:15:47 +0800442 struct platform_device *pdev = to_platform_device(dev);
Harini Katakam58bf0162014-08-22 14:58:01 +0530443 struct cdns_wdt *wdt = platform_get_drvdata(pdev);
444
445 ret = clk_prepare_enable(wdt->clk);
446 if (ret) {
447 dev_err(dev, "unable to enable clock\n");
448 return ret;
449 }
450 cdns_wdt_start(&wdt->cdns_wdt_device);
451
452 return 0;
453}
454
455static SIMPLE_DEV_PM_OPS(cdns_wdt_pm_ops, cdns_wdt_suspend, cdns_wdt_resume);
456
457static struct of_device_id cdns_wdt_of_match[] = {
458 { .compatible = "cdns,wdt-r1p2", },
459 { /* end of table */ }
460};
461MODULE_DEVICE_TABLE(of, cdns_wdt_of_match);
462
463/* Driver Structure */
464static struct platform_driver cdns_wdt_driver = {
465 .probe = cdns_wdt_probe,
466 .remove = cdns_wdt_remove,
467 .shutdown = cdns_wdt_shutdown,
468 .driver = {
469 .name = "cdns-wdt",
Harini Katakam58bf0162014-08-22 14:58:01 +0530470 .of_match_table = cdns_wdt_of_match,
471 .pm = &cdns_wdt_pm_ops,
472 },
473};
474
475module_platform_driver(cdns_wdt_driver);
476
477MODULE_AUTHOR("Xilinx, Inc.");
478MODULE_DESCRIPTION("Watchdog driver for Cadence WDT");
479MODULE_LICENSE("GPL");