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1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Cadence WDT driver - Used by Xilinx Zynq
4 *
5 * Copyright (C) 2010 - 2014 Xilinx, Inc.
6 *
7 */
8
9#include <linux/clk.h>
10#include <linux/init.h>
11#include <linux/interrupt.h>
12#include <linux/io.h>
13#include <linux/irq.h>
14#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/of.h>
17#include <linux/platform_device.h>
18#include <linux/watchdog.h>
19
20#define CDNS_WDT_DEFAULT_TIMEOUT 10
21/* Supports 1 - 516 sec */
22#define CDNS_WDT_MIN_TIMEOUT 1
23#define CDNS_WDT_MAX_TIMEOUT 516
24
25/* Restart key */
26#define CDNS_WDT_RESTART_KEY 0x00001999
27
28/* Counter register access key */
29#define CDNS_WDT_REGISTER_ACCESS_KEY 0x00920000
30
31/* Counter value divisor */
32#define CDNS_WDT_COUNTER_VALUE_DIVISOR 0x1000
33
34/* Clock prescaler value and selection */
35#define CDNS_WDT_PRESCALE_64 64
36#define CDNS_WDT_PRESCALE_512 512
37#define CDNS_WDT_PRESCALE_4096 4096
38#define CDNS_WDT_PRESCALE_SELECT_64 1
39#define CDNS_WDT_PRESCALE_SELECT_512 2
40#define CDNS_WDT_PRESCALE_SELECT_4096 3
41
42/* Input clock frequency */
43#define CDNS_WDT_CLK_10MHZ 10000000
44#define CDNS_WDT_CLK_75MHZ 75000000
45
46/* Counter maximum value */
47#define CDNS_WDT_COUNTER_MAX 0xFFF
48
49static int wdt_timeout;
50static int nowayout = WATCHDOG_NOWAYOUT;
51
52module_param(wdt_timeout, int, 0644);
53MODULE_PARM_DESC(wdt_timeout,
54 "Watchdog time in seconds. (default="
55 __MODULE_STRING(CDNS_WDT_DEFAULT_TIMEOUT) ")");
56
57module_param(nowayout, int, 0644);
58MODULE_PARM_DESC(nowayout,
59 "Watchdog cannot be stopped once started (default="
60 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
61
62/**
63 * struct cdns_wdt - Watchdog device structure
64 * @regs: baseaddress of device
65 * @rst: reset flag
66 * @clk: struct clk * of a clock source
67 * @prescaler: for saving prescaler value
68 * @ctrl_clksel: counter clock prescaler selection
69 * @io_lock: spinlock for IO register access
70 * @cdns_wdt_device: watchdog device structure
71 *
72 * Structure containing parameters specific to cadence watchdog.
73 */
74struct cdns_wdt {
75 void __iomem *regs;
76 bool rst;
77 struct clk *clk;
78 u32 prescaler;
79 u32 ctrl_clksel;
80 spinlock_t io_lock;
81 struct watchdog_device cdns_wdt_device;
82};
83
84/* Write access to Registers */
85static inline void cdns_wdt_writereg(struct cdns_wdt *wdt, u32 offset, u32 val)
86{
87 writel_relaxed(val, wdt->regs + offset);
88}
89
90/*************************Register Map**************************************/
91
92/* Register Offsets for the WDT */
93#define CDNS_WDT_ZMR_OFFSET 0x0 /* Zero Mode Register */
94#define CDNS_WDT_CCR_OFFSET 0x4 /* Counter Control Register */
95#define CDNS_WDT_RESTART_OFFSET 0x8 /* Restart Register */
96#define CDNS_WDT_SR_OFFSET 0xC /* Status Register */
97
98/*
99 * Zero Mode Register - This register controls how the time out is indicated
100 * and also contains the access code to allow writes to the register (0xABC).
101 */
102#define CDNS_WDT_ZMR_WDEN_MASK 0x00000001 /* Enable the WDT */
103#define CDNS_WDT_ZMR_RSTEN_MASK 0x00000002 /* Enable the reset output */
104#define CDNS_WDT_ZMR_IRQEN_MASK 0x00000004 /* Enable IRQ output */
105#define CDNS_WDT_ZMR_RSTLEN_16 0x00000030 /* Reset pulse of 16 pclk cycles */
106#define CDNS_WDT_ZMR_ZKEY_VAL 0x00ABC000 /* Access key, 0xABC << 12 */
107/*
108 * Counter Control register - This register controls how fast the timer runs
109 * and the reset value and also contains the access code to allow writes to
110 * the register.
111 */
112#define CDNS_WDT_CCR_CRV_MASK 0x00003FFC /* Counter reset value */
113
114/**
115 * cdns_wdt_stop - Stop the watchdog.
116 *
117 * @wdd: watchdog device
118 *
119 * Read the contents of the ZMR register, clear the WDEN bit
120 * in the register and set the access key for successful write.
121 *
122 * Return: always 0
123 */
124static int cdns_wdt_stop(struct watchdog_device *wdd)
125{
126 struct cdns_wdt *wdt = watchdog_get_drvdata(wdd);
127
128 spin_lock(&wdt->io_lock);
129 cdns_wdt_writereg(wdt, CDNS_WDT_ZMR_OFFSET,
130 CDNS_WDT_ZMR_ZKEY_VAL & (~CDNS_WDT_ZMR_WDEN_MASK));
131 spin_unlock(&wdt->io_lock);
132
133 return 0;
134}
135
136/**
137 * cdns_wdt_reload - Reload the watchdog timer (i.e. pat the watchdog).
138 *
139 * @wdd: watchdog device
140 *
141 * Write the restart key value (0x00001999) to the restart register.
142 *
143 * Return: always 0
144 */
145static int cdns_wdt_reload(struct watchdog_device *wdd)
146{
147 struct cdns_wdt *wdt = watchdog_get_drvdata(wdd);
148
149 spin_lock(&wdt->io_lock);
150 cdns_wdt_writereg(wdt, CDNS_WDT_RESTART_OFFSET,
151 CDNS_WDT_RESTART_KEY);
152 spin_unlock(&wdt->io_lock);
153
154 return 0;
155}
156
157/**
158 * cdns_wdt_start - Enable and start the watchdog.
159 *
160 * @wdd: watchdog device
161 *
162 * The counter value is calculated according to the formula:
163 * calculated count = (timeout * clock) / prescaler + 1.
164 * The calculated count is divided by 0x1000 to obtain the field value
165 * to write to counter control register.
166 * Clears the contents of prescaler and counter reset value. Sets the
167 * prescaler to 4096 and the calculated count and access key
168 * to write to CCR Register.
169 * Sets the WDT (WDEN bit) and either the Reset signal(RSTEN bit)
170 * or Interrupt signal(IRQEN) with a specified cycles and the access
171 * key to write to ZMR Register.
172 *
173 * Return: always 0
174 */
175static int cdns_wdt_start(struct watchdog_device *wdd)
176{
177 struct cdns_wdt *wdt = watchdog_get_drvdata(wdd);
178 unsigned int data = 0;
179 unsigned short count;
180 unsigned long clock_f = clk_get_rate(wdt->clk);
181
182 /*
183 * Counter value divisor to obtain the value of
184 * counter reset to be written to control register.
185 */
186 count = (wdd->timeout * (clock_f / wdt->prescaler)) /
187 CDNS_WDT_COUNTER_VALUE_DIVISOR + 1;
188
189 if (count > CDNS_WDT_COUNTER_MAX)
190 count = CDNS_WDT_COUNTER_MAX;
191
192 spin_lock(&wdt->io_lock);
193 cdns_wdt_writereg(wdt, CDNS_WDT_ZMR_OFFSET,
194 CDNS_WDT_ZMR_ZKEY_VAL);
195
196 count = (count << 2) & CDNS_WDT_CCR_CRV_MASK;
197
198 /* Write counter access key first to be able write to register */
199 data = count | CDNS_WDT_REGISTER_ACCESS_KEY | wdt->ctrl_clksel;
200 cdns_wdt_writereg(wdt, CDNS_WDT_CCR_OFFSET, data);
201 data = CDNS_WDT_ZMR_WDEN_MASK | CDNS_WDT_ZMR_RSTLEN_16 |
202 CDNS_WDT_ZMR_ZKEY_VAL;
203
204 /* Reset on timeout if specified in device tree. */
205 if (wdt->rst) {
206 data |= CDNS_WDT_ZMR_RSTEN_MASK;
207 data &= ~CDNS_WDT_ZMR_IRQEN_MASK;
208 } else {
209 data &= ~CDNS_WDT_ZMR_RSTEN_MASK;
210 data |= CDNS_WDT_ZMR_IRQEN_MASK;
211 }
212 cdns_wdt_writereg(wdt, CDNS_WDT_ZMR_OFFSET, data);
213 cdns_wdt_writereg(wdt, CDNS_WDT_RESTART_OFFSET,
214 CDNS_WDT_RESTART_KEY);
215 spin_unlock(&wdt->io_lock);
216
217 return 0;
218}
219
220/**
221 * cdns_wdt_settimeout - Set a new timeout value for the watchdog device.
222 *
223 * @wdd: watchdog device
224 * @new_time: new timeout value that needs to be set
225 * Return: 0 on success
226 *
227 * Update the watchdog_device timeout with new value which is used when
228 * cdns_wdt_start is called.
229 */
230static int cdns_wdt_settimeout(struct watchdog_device *wdd,
231 unsigned int new_time)
232{
233 wdd->timeout = new_time;
234
235 return cdns_wdt_start(wdd);
236}
237
238/**
239 * cdns_wdt_irq_handler - Notifies of watchdog timeout.
240 *
241 * @irq: interrupt number
242 * @dev_id: pointer to a platform device structure
243 * Return: IRQ_HANDLED
244 *
245 * The handler is invoked when the watchdog times out and a
246 * reset on timeout has not been enabled.
247 */
248static irqreturn_t cdns_wdt_irq_handler(int irq, void *dev_id)
249{
250 struct platform_device *pdev = dev_id;
251
252 dev_info(&pdev->dev,
253 "Watchdog timed out. Internal reset not enabled\n");
254
255 return IRQ_HANDLED;
256}
257
258/*
259 * Info structure used to indicate the features supported by the device
260 * to the upper layers. This is defined in watchdog.h header file.
261 */
262static const struct watchdog_info cdns_wdt_info = {
263 .identity = "cdns_wdt watchdog",
264 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
265 WDIOF_MAGICCLOSE,
266};
267
268/* Watchdog Core Ops */
269static const struct watchdog_ops cdns_wdt_ops = {
270 .owner = THIS_MODULE,
271 .start = cdns_wdt_start,
272 .stop = cdns_wdt_stop,
273 .ping = cdns_wdt_reload,
274 .set_timeout = cdns_wdt_settimeout,
275};
276
277/************************Platform Operations*****************************/
278/**
279 * cdns_wdt_probe - Probe call for the device.
280 *
281 * @pdev: handle to the platform device structure.
282 * Return: 0 on success, negative error otherwise.
283 *
284 * It does all the memory allocation and registration for the device.
285 */
286static int cdns_wdt_probe(struct platform_device *pdev)
287{
288 struct device *dev = &pdev->dev;
289 int ret, irq;
290 unsigned long clock_f;
291 struct cdns_wdt *wdt;
292 struct watchdog_device *cdns_wdt_device;
293
294 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
295 if (!wdt)
296 return -ENOMEM;
297
298 cdns_wdt_device = &wdt->cdns_wdt_device;
299 cdns_wdt_device->info = &cdns_wdt_info;
300 cdns_wdt_device->ops = &cdns_wdt_ops;
301 cdns_wdt_device->timeout = CDNS_WDT_DEFAULT_TIMEOUT;
302 cdns_wdt_device->min_timeout = CDNS_WDT_MIN_TIMEOUT;
303 cdns_wdt_device->max_timeout = CDNS_WDT_MAX_TIMEOUT;
304
305 wdt->regs = devm_platform_ioremap_resource(pdev, 0);
306 if (IS_ERR(wdt->regs))
307 return PTR_ERR(wdt->regs);
308
309 /* Register the interrupt */
310 wdt->rst = of_property_read_bool(dev->of_node, "reset-on-timeout");
311 irq = platform_get_irq(pdev, 0);
312 if (!wdt->rst && irq >= 0) {
313 ret = devm_request_irq(dev, irq, cdns_wdt_irq_handler, 0,
314 pdev->name, pdev);
315 if (ret)
316 return ret;
317 }
318
319 /* Initialize the members of cdns_wdt structure */
320 cdns_wdt_device->parent = dev;
321
322 watchdog_init_timeout(cdns_wdt_device, wdt_timeout, dev);
323 watchdog_set_nowayout(cdns_wdt_device, nowayout);
324 watchdog_stop_on_reboot(cdns_wdt_device);
325 watchdog_set_drvdata(cdns_wdt_device, wdt);
326
327 wdt->clk = devm_clk_get_enabled(dev, NULL);
328 if (IS_ERR(wdt->clk))
329 return dev_err_probe(dev, PTR_ERR(wdt->clk),
330 "input clock not found\n");
331
332 clock_f = clk_get_rate(wdt->clk);
333 if (clock_f <= CDNS_WDT_CLK_75MHZ) {
334 wdt->prescaler = CDNS_WDT_PRESCALE_512;
335 wdt->ctrl_clksel = CDNS_WDT_PRESCALE_SELECT_512;
336 } else {
337 wdt->prescaler = CDNS_WDT_PRESCALE_4096;
338 wdt->ctrl_clksel = CDNS_WDT_PRESCALE_SELECT_4096;
339 }
340
341 spin_lock_init(&wdt->io_lock);
342
343 watchdog_stop_on_reboot(cdns_wdt_device);
344 watchdog_stop_on_unregister(cdns_wdt_device);
345 ret = devm_watchdog_register_device(dev, cdns_wdt_device);
346 if (ret)
347 return ret;
348 platform_set_drvdata(pdev, wdt);
349
350 dev_info(dev, "Xilinx Watchdog Timer with timeout %ds%s\n",
351 cdns_wdt_device->timeout, nowayout ? ", nowayout" : "");
352
353 return 0;
354}
355
356/**
357 * cdns_wdt_suspend - Stop the device.
358 *
359 * @dev: handle to the device structure.
360 * Return: 0 always.
361 */
362static int __maybe_unused cdns_wdt_suspend(struct device *dev)
363{
364 struct cdns_wdt *wdt = dev_get_drvdata(dev);
365
366 if (watchdog_active(&wdt->cdns_wdt_device)) {
367 cdns_wdt_stop(&wdt->cdns_wdt_device);
368 clk_disable_unprepare(wdt->clk);
369 }
370
371 return 0;
372}
373
374/**
375 * cdns_wdt_resume - Resume the device.
376 *
377 * @dev: handle to the device structure.
378 * Return: 0 on success, errno otherwise.
379 */
380static int __maybe_unused cdns_wdt_resume(struct device *dev)
381{
382 int ret;
383 struct cdns_wdt *wdt = dev_get_drvdata(dev);
384
385 if (watchdog_active(&wdt->cdns_wdt_device)) {
386 ret = clk_prepare_enable(wdt->clk);
387 if (ret) {
388 dev_err(dev, "unable to enable clock\n");
389 return ret;
390 }
391 cdns_wdt_start(&wdt->cdns_wdt_device);
392 }
393
394 return 0;
395}
396
397static SIMPLE_DEV_PM_OPS(cdns_wdt_pm_ops, cdns_wdt_suspend, cdns_wdt_resume);
398
399static const struct of_device_id cdns_wdt_of_match[] = {
400 { .compatible = "cdns,wdt-r1p2", },
401 { /* end of table */ }
402};
403MODULE_DEVICE_TABLE(of, cdns_wdt_of_match);
404
405/* Driver Structure */
406static struct platform_driver cdns_wdt_driver = {
407 .probe = cdns_wdt_probe,
408 .driver = {
409 .name = "cdns-wdt",
410 .of_match_table = cdns_wdt_of_match,
411 .pm = &cdns_wdt_pm_ops,
412 },
413};
414
415module_platform_driver(cdns_wdt_driver);
416
417MODULE_AUTHOR("Xilinx, Inc.");
418MODULE_DESCRIPTION("Watchdog driver for Cadence WDT");
419MODULE_LICENSE("GPL");