1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * drivers/char/watchdog/sp805-wdt.c
4 *
5 * Watchdog driver for ARM SP805 watchdog module
6 *
7 * Copyright (C) 2010 ST Microelectronics
8 * Viresh Kumar <vireshk@kernel.org>
9 *
10 * This file is licensed under the terms of the GNU General Public
11 * License version 2 or later. This program is licensed "as is" without any
12 * warranty of any kind, whether express or implied.
13 */
14
15#include <linux/device.h>
16#include <linux/resource.h>
17#include <linux/amba/bus.h>
18#include <linux/bitops.h>
19#include <linux/clk.h>
20#include <linux/io.h>
21#include <linux/ioport.h>
22#include <linux/kernel.h>
23#include <linux/math64.h>
24#include <linux/module.h>
25#include <linux/moduleparam.h>
26#include <linux/pm.h>
27#include <linux/property.h>
28#include <linux/slab.h>
29#include <linux/spinlock.h>
30#include <linux/types.h>
31#include <linux/watchdog.h>
32
33/* default timeout in seconds */
34#define DEFAULT_TIMEOUT 60
35
36#define MODULE_NAME "sp805-wdt"
37
38/* watchdog register offsets and masks */
39#define WDTLOAD 0x000
40 #define LOAD_MIN 0x00000001
41 #define LOAD_MAX 0xFFFFFFFF
42#define WDTVALUE 0x004
43#define WDTCONTROL 0x008
44 /* control register masks */
45 #define INT_ENABLE (1 << 0)
46 #define RESET_ENABLE (1 << 1)
47 #define ENABLE_MASK (INT_ENABLE | RESET_ENABLE)
48#define WDTINTCLR 0x00C
49#define WDTRIS 0x010
50#define WDTMIS 0x014
51 #define INT_MASK (1 << 0)
52#define WDTLOCK 0xC00
53 #define UNLOCK 0x1ACCE551
54 #define LOCK 0x00000001
55
56/**
57 * struct sp805_wdt: sp805 wdt device structure
58 * @wdd: instance of struct watchdog_device
59 * @lock: spin lock protecting dev structure and io access
60 * @base: base address of wdt
61 * @clk: (optional) clock structure of wdt
62 * @rate: (optional) clock rate when provided via properties
63 * @adev: amba device structure of wdt
64 * @status: current status of wdt
65 * @load_val: load value to be set for current timeout
66 */
67struct sp805_wdt {
68 struct watchdog_device wdd;
69 spinlock_t lock;
70 void __iomem *base;
71 struct clk *clk;
72 u64 rate;
73 struct amba_device *adev;
74 unsigned int load_val;
75};
76
77static bool nowayout = WATCHDOG_NOWAYOUT;
78module_param(nowayout, bool, 0);
79MODULE_PARM_DESC(nowayout,
80 "Set to 1 to keep watchdog running after device release");
81
82/* returns true if wdt is running; otherwise returns false */
83static bool wdt_is_running(struct watchdog_device *wdd)
84{
85 struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
86 u32 wdtcontrol = readl_relaxed(wdt->base + WDTCONTROL);
87
88 return (wdtcontrol & ENABLE_MASK) == ENABLE_MASK;
89}
90
91/* This routine finds load value that will reset system in required timeout */
92static int wdt_setload(struct watchdog_device *wdd, unsigned int timeout)
93{
94 struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
95 u64 load, rate;
96
97 rate = wdt->rate;
98
99 /*
100 * sp805 runs counter with given value twice, after the end of first
101 * counter it gives an interrupt and then starts counter again. If
102 * interrupt already occurred then it resets the system. This is why
103 * load is half of what should be required.
104 */
105 load = div_u64(dividend: rate, divisor: 2) * timeout - 1;
106
107 load = (load > LOAD_MAX) ? LOAD_MAX : load;
108 load = (load < LOAD_MIN) ? LOAD_MIN : load;
109
110 spin_lock(lock: &wdt->lock);
111 wdt->load_val = load;
112 /* roundup timeout to closest positive integer value */
113 wdd->timeout = div_u64(dividend: (load + 1) * 2 + (rate / 2), divisor: rate);
114 spin_unlock(lock: &wdt->lock);
115
116 return 0;
117}
118
119/* returns number of seconds left for reset to occur */
120static unsigned int wdt_timeleft(struct watchdog_device *wdd)
121{
122 struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
123 u64 load;
124
125 spin_lock(lock: &wdt->lock);
126 load = readl_relaxed(wdt->base + WDTVALUE);
127
128 /*If the interrupt is inactive then time left is WDTValue + WDTLoad. */
129 if (!(readl_relaxed(wdt->base + WDTRIS) & INT_MASK))
130 load += wdt->load_val + 1;
131 spin_unlock(lock: &wdt->lock);
132
133 return div_u64(dividend: load, divisor: wdt->rate);
134}
135
136static int
137wdt_restart(struct watchdog_device *wdd, unsigned long mode, void *cmd)
138{
139 struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
140
141 writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
142 writel_relaxed(0, wdt->base + WDTCONTROL);
143 writel_relaxed(0, wdt->base + WDTLOAD);
144 writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base + WDTCONTROL);
145
146 /* Flush posted writes. */
147 readl_relaxed(wdt->base + WDTLOCK);
148
149 return 0;
150}
151
152static int wdt_config(struct watchdog_device *wdd, bool ping)
153{
154 struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
155 int ret;
156
157 if (!ping) {
158
159 ret = clk_prepare_enable(clk: wdt->clk);
160 if (ret) {
161 dev_err(&wdt->adev->dev, "clock enable fail");
162 return ret;
163 }
164 }
165
166 spin_lock(lock: &wdt->lock);
167
168 writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
169 writel_relaxed(wdt->load_val, wdt->base + WDTLOAD);
170 writel_relaxed(INT_MASK, wdt->base + WDTINTCLR);
171
172 if (!ping)
173 writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base +
174 WDTCONTROL);
175
176 writel_relaxed(LOCK, wdt->base + WDTLOCK);
177
178 /* Flush posted writes. */
179 readl_relaxed(wdt->base + WDTLOCK);
180 spin_unlock(lock: &wdt->lock);
181
182 return 0;
183}
184
185static int wdt_ping(struct watchdog_device *wdd)
186{
187 return wdt_config(wdd, ping: true);
188}
189
190/* enables watchdog timers reset */
191static int wdt_enable(struct watchdog_device *wdd)
192{
193 return wdt_config(wdd, ping: false);
194}
195
196/* disables watchdog timers reset */
197static int wdt_disable(struct watchdog_device *wdd)
198{
199 struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
200
201 spin_lock(lock: &wdt->lock);
202
203 writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
204 writel_relaxed(0, wdt->base + WDTCONTROL);
205 writel_relaxed(LOCK, wdt->base + WDTLOCK);
206
207 /* Flush posted writes. */
208 readl_relaxed(wdt->base + WDTLOCK);
209 spin_unlock(lock: &wdt->lock);
210
211 clk_disable_unprepare(clk: wdt->clk);
212
213 return 0;
214}
215
216static const struct watchdog_info wdt_info = {
217 .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
218 .identity = MODULE_NAME,
219};
220
221static const struct watchdog_ops wdt_ops = {
222 .owner = THIS_MODULE,
223 .start = wdt_enable,
224 .stop = wdt_disable,
225 .ping = wdt_ping,
226 .set_timeout = wdt_setload,
227 .get_timeleft = wdt_timeleft,
228 .restart = wdt_restart,
229};
230
231static int
232sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
233{
234 struct sp805_wdt *wdt;
235 u64 rate = 0;
236 int ret = 0;
237
238 wdt = devm_kzalloc(dev: &adev->dev, size: sizeof(*wdt), GFP_KERNEL);
239 if (!wdt) {
240 ret = -ENOMEM;
241 goto err;
242 }
243
244 wdt->base = devm_ioremap_resource(dev: &adev->dev, res: &adev->res);
245 if (IS_ERR(ptr: wdt->base))
246 return PTR_ERR(ptr: wdt->base);
247
248 /*
249 * When driver probe with ACPI device, clock devices
250 * are not available, so watchdog rate get from
251 * clock-frequency property given in _DSD object.
252 */
253 device_property_read_u64(dev: &adev->dev, propname: "clock-frequency", val: &rate);
254
255 wdt->clk = devm_clk_get_optional(dev: &adev->dev, NULL);
256 if (IS_ERR(ptr: wdt->clk))
257 return dev_err_probe(dev: &adev->dev, err: PTR_ERR(ptr: wdt->clk), fmt: "Clock not found\n");
258
259 wdt->rate = clk_get_rate(clk: wdt->clk);
260 if (!wdt->rate)
261 wdt->rate = rate;
262 if (!wdt->rate) {
263 dev_err(&adev->dev, "no clock-frequency property\n");
264 return -ENODEV;
265 }
266
267 wdt->adev = adev;
268 wdt->wdd.info = &wdt_info;
269 wdt->wdd.ops = &wdt_ops;
270 wdt->wdd.parent = &adev->dev;
271
272 spin_lock_init(&wdt->lock);
273 watchdog_set_nowayout(wdd: &wdt->wdd, nowayout);
274 watchdog_set_drvdata(wdd: &wdt->wdd, data: wdt);
275 watchdog_set_restart_priority(wdd: &wdt->wdd, priority: 128);
276 watchdog_stop_on_unregister(wdd: &wdt->wdd);
277
278 /*
279 * If 'timeout-sec' devicetree property is specified, use that.
280 * Otherwise, use DEFAULT_TIMEOUT
281 */
282 wdt->wdd.timeout = DEFAULT_TIMEOUT;
283 watchdog_init_timeout(wdd: &wdt->wdd, timeout_parm: 0, dev: &adev->dev);
284 wdt_setload(wdd: &wdt->wdd, timeout: wdt->wdd.timeout);
285
286 /*
287 * If HW is already running, enable/reset the wdt and set the running
288 * bit to tell the wdt subsystem
289 */
290 if (wdt_is_running(wdd: &wdt->wdd)) {
291 wdt_enable(wdd: &wdt->wdd);
292 set_bit(WDOG_HW_RUNNING, addr: &wdt->wdd.status);
293 }
294
295 watchdog_stop_on_reboot(wdd: &wdt->wdd);
296 ret = watchdog_register_device(&wdt->wdd);
297 if (ret)
298 goto err;
299 amba_set_drvdata(adev, wdt);
300
301 dev_info(&adev->dev, "registration successful\n");
302 return 0;
303
304err:
305 dev_err(&adev->dev, "Probe Failed!!!\n");
306 return ret;
307}
308
309static void sp805_wdt_remove(struct amba_device *adev)
310{
311 struct sp805_wdt *wdt = amba_get_drvdata(adev);
312
313 watchdog_unregister_device(&wdt->wdd);
314 watchdog_set_drvdata(wdd: &wdt->wdd, NULL);
315}
316
317static int __maybe_unused sp805_wdt_suspend(struct device *dev)
318{
319 struct sp805_wdt *wdt = dev_get_drvdata(dev);
320
321 if (watchdog_active(wdd: &wdt->wdd))
322 return wdt_disable(wdd: &wdt->wdd);
323
324 return 0;
325}
326
327static int __maybe_unused sp805_wdt_resume(struct device *dev)
328{
329 struct sp805_wdt *wdt = dev_get_drvdata(dev);
330
331 if (watchdog_active(wdd: &wdt->wdd))
332 return wdt_enable(wdd: &wdt->wdd);
333
334 return 0;
335}
336
337static SIMPLE_DEV_PM_OPS(sp805_wdt_dev_pm_ops, sp805_wdt_suspend,
338 sp805_wdt_resume);
339
340static const struct amba_id sp805_wdt_ids[] = {
341 {
342 .id = 0x00141805,
343 .mask = 0x00ffffff,
344 },
345 {
346 .id = 0x001bb824,
347 .mask = 0x00ffffff,
348 },
349 { 0, 0 },
350};
351
352MODULE_DEVICE_TABLE(amba, sp805_wdt_ids);
353
354static struct amba_driver sp805_wdt_driver = {
355 .drv = {
356 .name = MODULE_NAME,
357 .pm = &sp805_wdt_dev_pm_ops,
358 },
359 .id_table = sp805_wdt_ids,
360 .probe = sp805_wdt_probe,
361 .remove = sp805_wdt_remove,
362};
363
364module_amba_driver(sp805_wdt_driver);
365
366MODULE_AUTHOR("Viresh Kumar <vireshk@kernel.org>");
367MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
368MODULE_LICENSE("GPL");
369

source code of linux/drivers/watchdog/sp805_wdt.c