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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * SBSA(Server Base System Architecture) Generic Watchdog driver
4 *
5 * Copyright (c) 2015, Linaro Ltd.
6 * Author: Fu Wei <fu.wei@linaro.org>
7 * Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
8 * Al Stone <al.stone@linaro.org>
9 * Timur Tabi <timur@codeaurora.org>
10 *
11 * ARM SBSA Generic Watchdog has two stage timeouts:
12 * the first signal (WS0) is for alerting the system by interrupt,
13 * the second one (WS1) is a real hardware reset.
14 * More details about the hardware specification of this device:
15 * ARM DEN0029B - Server Base System Architecture (SBSA)
16 *
17 * This driver can operate ARM SBSA Generic Watchdog as a single stage watchdog
18 * or a two stages watchdog, it's set up by the module parameter "action".
19 * In the single stage mode, when the timeout is reached, your system
20 * will be reset by WS1. The first signal (WS0) is ignored.
21 * In the two stages mode, when the timeout is reached, the first signal (WS0)
22 * will trigger panic. If the system is getting into trouble and cannot be reset
23 * by panic or restart properly by the kdump kernel(if supported), then the
24 * second stage (as long as the first stage) will be reached, system will be
25 * reset by WS1. This function can help administrator to backup the system
26 * context info by panic console output or kdump.
27 *
28 * SBSA GWDT:
29 * if action is 1 (the two stages mode):
30 * |--------WOR-------WS0--------WOR-------WS1
31 * |----timeout-----(panic)----timeout-----reset
32 *
33 * if action is 0 (the single stage mode):
34 * |------WOR-----WS0(ignored)-----WOR------WS1
35 * |--------------timeout-------------------reset
36 *
37 * Note: Since this watchdog timer has two stages, and each stage is determined
38 * by WOR, in the single stage mode, the timeout is (WOR * 2); in the two
39 * stages mode, the timeout is WOR. The maximum timeout in the two stages mode
40 * is half of that in the single stage mode.
41 */
42
43#include <linux/io.h>
44#include <linux/io-64-nonatomic-lo-hi.h>
45#include <linux/interrupt.h>
46#include <linux/module.h>
47#include <linux/moduleparam.h>
48#include <linux/of.h>
49#include <linux/of_device.h>
50#include <linux/platform_device.h>
51#include <linux/uaccess.h>
52#include <linux/watchdog.h>
53#include <asm/arch_timer.h>
54
55#define DRV_NAME "sbsa-gwdt"
56#define WATCHDOG_NAME "SBSA Generic Watchdog"
57
58/* SBSA Generic Watchdog register definitions */
59/* refresh frame */
60#define SBSA_GWDT_WRR 0x000
61
62/* control frame */
63#define SBSA_GWDT_WCS 0x000
64#define SBSA_GWDT_WOR 0x008
65#define SBSA_GWDT_WCV 0x010
66
67/* refresh/control frame */
68#define SBSA_GWDT_W_IIDR 0xfcc
69#define SBSA_GWDT_IDR 0xfd0
70
71/* Watchdog Control and Status Register */
72#define SBSA_GWDT_WCS_EN BIT(0)
73#define SBSA_GWDT_WCS_WS0 BIT(1)
74#define SBSA_GWDT_WCS_WS1 BIT(2)
75
76/**
77 * struct sbsa_gwdt - Internal representation of the SBSA GWDT
78 * @wdd: kernel watchdog_device structure
79 * @clk: store the System Counter clock frequency, in Hz.
80 * @refresh_base: Virtual address of the watchdog refresh frame
81 * @control_base: Virtual address of the watchdog control frame
82 */
83struct sbsa_gwdt {
84 struct watchdog_device wdd;
85 u32 clk;
86 void __iomem *refresh_base;
87 void __iomem *control_base;
88};
89
90#define DEFAULT_TIMEOUT 10 /* seconds */
91
92static unsigned int timeout;
93module_param(timeout, uint, 0);
94MODULE_PARM_DESC(timeout,
95 "Watchdog timeout in seconds. (>=0, default="
96 __MODULE_STRING(DEFAULT_TIMEOUT) ")");
97
98/*
99 * action refers to action taken when watchdog gets WS0
100 * 0 = skip
101 * 1 = panic
102 * defaults to skip (0)
103 */
104static int action;
105module_param(action, int, 0);
106MODULE_PARM_DESC(action, "after watchdog gets WS0 interrupt, do: "
107 "0 = skip(*) 1 = panic");
108
109static bool nowayout = WATCHDOG_NOWAYOUT;
110module_param(nowayout, bool, S_IRUGO);
111MODULE_PARM_DESC(nowayout,
112 "Watchdog cannot be stopped once started (default="
113 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
114
115/*
116 * watchdog operation functions
117 */
118static int sbsa_gwdt_set_timeout(struct watchdog_device *wdd,
119 unsigned int timeout)
120{
121 struct sbsa_gwdt *gwdt = watchdog_get_drvdata(wdd);
122
123 wdd->timeout = timeout;
124
125 if (action)
126 writel(gwdt->clk * timeout,
127 gwdt->control_base + SBSA_GWDT_WOR);
128 else
129 /*
130 * In the single stage mode, The first signal (WS0) is ignored,
131 * the timeout is (WOR * 2), so the WOR should be configured
132 * to half value of timeout.
133 */
134 writel(gwdt->clk / 2 * timeout,
135 gwdt->control_base + SBSA_GWDT_WOR);
136
137 return 0;
138}
139
140static unsigned int sbsa_gwdt_get_timeleft(struct watchdog_device *wdd)
141{
142 struct sbsa_gwdt *gwdt = watchdog_get_drvdata(wdd);
143 u64 timeleft = 0;
144
145 /*
146 * In the single stage mode, if WS0 is deasserted
147 * (watchdog is in the first stage),
148 * timeleft = WOR + (WCV - system counter)
149 */
150 if (!action &&
151 !(readl(gwdt->control_base + SBSA_GWDT_WCS) & SBSA_GWDT_WCS_WS0))
152 timeleft += readl(gwdt->control_base + SBSA_GWDT_WOR);
153
154 timeleft += lo_hi_readq(gwdt->control_base + SBSA_GWDT_WCV) -
155 arch_timer_read_counter();
156
157 do_div(timeleft, gwdt->clk);
158
159 return timeleft;
160}
161
162static int sbsa_gwdt_keepalive(struct watchdog_device *wdd)
163{
164 struct sbsa_gwdt *gwdt = watchdog_get_drvdata(wdd);
165
166 /*
167 * Writing WRR for an explicit watchdog refresh.
168 * You can write anyting (like 0).
169 */
170 writel(0, gwdt->refresh_base + SBSA_GWDT_WRR);
171
172 return 0;
173}
174
175static int sbsa_gwdt_start(struct watchdog_device *wdd)
176{
177 struct sbsa_gwdt *gwdt = watchdog_get_drvdata(wdd);
178
179 /* writing WCS will cause an explicit watchdog refresh */
180 writel(SBSA_GWDT_WCS_EN, gwdt->control_base + SBSA_GWDT_WCS);
181
182 return 0;
183}
184
185static int sbsa_gwdt_stop(struct watchdog_device *wdd)
186{
187 struct sbsa_gwdt *gwdt = watchdog_get_drvdata(wdd);
188
189 /* Simply write 0 to WCS to clean WCS_EN bit */
190 writel(0, gwdt->control_base + SBSA_GWDT_WCS);
191
192 return 0;
193}
194
195static irqreturn_t sbsa_gwdt_interrupt(int irq, void *dev_id)
196{
197 panic(WATCHDOG_NAME " timeout");
198
199 return IRQ_HANDLED;
200}
201
202static const struct watchdog_info sbsa_gwdt_info = {
203 .identity = WATCHDOG_NAME,
204 .options = WDIOF_SETTIMEOUT |
205 WDIOF_KEEPALIVEPING |
206 WDIOF_MAGICCLOSE |
207 WDIOF_CARDRESET,
208};
209
210static const struct watchdog_ops sbsa_gwdt_ops = {
211 .owner = THIS_MODULE,
212 .start = sbsa_gwdt_start,
213 .stop = sbsa_gwdt_stop,
214 .ping = sbsa_gwdt_keepalive,
215 .set_timeout = sbsa_gwdt_set_timeout,
216 .get_timeleft = sbsa_gwdt_get_timeleft,
217};
218
219static int sbsa_gwdt_probe(struct platform_device *pdev)
220{
221 void __iomem *rf_base, *cf_base;
222 struct device *dev = &pdev->dev;
223 struct watchdog_device *wdd;
224 struct sbsa_gwdt *gwdt;
225 int ret, irq;
226 u32 status;
227
228 gwdt = devm_kzalloc(dev, sizeof(*gwdt), GFP_KERNEL);
229 if (!gwdt)
230 return -ENOMEM;
231 platform_set_drvdata(pdev, gwdt);
232
233 cf_base = devm_platform_ioremap_resource(pdev, 0);
234 if (IS_ERR(cf_base))
235 return PTR_ERR(cf_base);
236
237 rf_base = devm_platform_ioremap_resource(pdev, 1);
238 if (IS_ERR(rf_base))
239 return PTR_ERR(rf_base);
240
241 /*
242 * Get the frequency of system counter from the cp15 interface of ARM
243 * Generic timer. We don't need to check it, because if it returns "0",
244 * system would panic in very early stage.
245 */
246 gwdt->clk = arch_timer_get_cntfrq();
247 gwdt->refresh_base = rf_base;
248 gwdt->control_base = cf_base;
249
250 wdd = &gwdt->wdd;
251 wdd->parent = dev;
252 wdd->info = &sbsa_gwdt_info;
253 wdd->ops = &sbsa_gwdt_ops;
254 wdd->min_timeout = 1;
255 wdd->max_hw_heartbeat_ms = U32_MAX / gwdt->clk * 1000;
256 wdd->timeout = DEFAULT_TIMEOUT;
257 watchdog_set_drvdata(wdd, gwdt);
258 watchdog_set_nowayout(wdd, nowayout);
259
260 status = readl(cf_base + SBSA_GWDT_WCS);
261 if (status & SBSA_GWDT_WCS_WS1) {
262 dev_warn(dev, "System reset by WDT.\n");
263 wdd->bootstatus |= WDIOF_CARDRESET;
264 }
265 if (status & SBSA_GWDT_WCS_EN)
266 set_bit(WDOG_HW_RUNNING, &wdd->status);
267
268 if (action) {
269 irq = platform_get_irq(pdev, 0);
270 if (irq < 0) {
271 action = 0;
272 dev_warn(dev, "unable to get ws0 interrupt.\n");
273 } else {
274 /*
275 * In case there is a pending ws0 interrupt, just ping
276 * the watchdog before registering the interrupt routine
277 */
278 writel(0, rf_base + SBSA_GWDT_WRR);
279 if (devm_request_irq(dev, irq, sbsa_gwdt_interrupt, 0,
280 pdev->name, gwdt)) {
281 action = 0;
282 dev_warn(dev, "unable to request IRQ %d.\n",
283 irq);
284 }
285 }
286 if (!action)
287 dev_warn(dev, "falling back to single stage mode.\n");
288 }
289 /*
290 * In the single stage mode, The first signal (WS0) is ignored,
291 * the timeout is (WOR * 2), so the maximum timeout should be doubled.
292 */
293 if (!action)
294 wdd->max_hw_heartbeat_ms *= 2;
295
296 watchdog_init_timeout(wdd, timeout, dev);
297 /*
298 * Update timeout to WOR.
299 * Because of the explicit watchdog refresh mechanism,
300 * it's also a ping, if watchdog is enabled.
301 */
302 sbsa_gwdt_set_timeout(wdd, wdd->timeout);
303
304 watchdog_stop_on_reboot(wdd);
305 ret = devm_watchdog_register_device(dev, wdd);
306 if (ret)
307 return ret;
308
309 dev_info(dev, "Initialized with %ds timeout @ %u Hz, action=%d.%s\n",
310 wdd->timeout, gwdt->clk, action,
311 status & SBSA_GWDT_WCS_EN ? " [enabled]" : "");
312
313 return 0;
314}
315
316/* Disable watchdog if it is active during suspend */
317static int __maybe_unused sbsa_gwdt_suspend(struct device *dev)
318{
319 struct sbsa_gwdt *gwdt = dev_get_drvdata(dev);
320
321 if (watchdog_active(&gwdt->wdd))
322 sbsa_gwdt_stop(&gwdt->wdd);
323
324 return 0;
325}
326
327/* Enable watchdog if necessary */
328static int __maybe_unused sbsa_gwdt_resume(struct device *dev)
329{
330 struct sbsa_gwdt *gwdt = dev_get_drvdata(dev);
331
332 if (watchdog_active(&gwdt->wdd))
333 sbsa_gwdt_start(&gwdt->wdd);
334
335 return 0;
336}
337
338static const struct dev_pm_ops sbsa_gwdt_pm_ops = {
339 SET_SYSTEM_SLEEP_PM_OPS(sbsa_gwdt_suspend, sbsa_gwdt_resume)
340};
341
342static const struct of_device_id sbsa_gwdt_of_match[] = {
343 { .compatible = "arm,sbsa-gwdt", },
344 {},
345};
346MODULE_DEVICE_TABLE(of, sbsa_gwdt_of_match);
347
348static const struct platform_device_id sbsa_gwdt_pdev_match[] = {
349 { .name = DRV_NAME, },
350 {},
351};
352MODULE_DEVICE_TABLE(platform, sbsa_gwdt_pdev_match);
353
354static struct platform_driver sbsa_gwdt_driver = {
355 .driver = {
356 .name = DRV_NAME,
357 .pm = &sbsa_gwdt_pm_ops,
358 .of_match_table = sbsa_gwdt_of_match,
359 },
360 .probe = sbsa_gwdt_probe,
361 .id_table = sbsa_gwdt_pdev_match,
362};
363
364module_platform_driver(sbsa_gwdt_driver);
365
366MODULE_DESCRIPTION("SBSA Generic Watchdog Driver");
367MODULE_AUTHOR("Fu Wei <fu.wei@linaro.org>");
368MODULE_AUTHOR("Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>");
369MODULE_AUTHOR("Al Stone <al.stone@linaro.org>");
370MODULE_AUTHOR("Timur Tabi <timur@codeaurora.org>");
371MODULE_LICENSE("GPL v2");
372MODULE_ALIAS("platform:" DRV_NAME);