1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Watchdog driver for Marvell Armada 37xx SoCs
4  *
5  * Author: Marek Behún <kabel@kernel.org>
6  */
7 
8 #include <linux/clk.h>
9 #include <linux/err.h>
10 #include <linux/interrupt.h>
11 #include <linux/io.h>
12 #include <linux/kernel.h>
13 #include <linux/mfd/syscon.h>
14 #include <linux/module.h>
15 #include <linux/moduleparam.h>
16 #include <linux/of.h>
17 #include <linux/platform_device.h>
18 #include <linux/regmap.h>
19 #include <linux/types.h>
20 #include <linux/watchdog.h>
21 
22 /*
23  * There are four counters that can be used for watchdog on Armada 37xx.
24  * The addresses for counter control registers are register base plus ID*0x10,
25  * where ID is 0, 1, 2 or 3.
26  *
27  * In this driver we use IDs 0 and 1. Counter ID 1 is used as watchdog counter,
28  * while counter ID 0 is used to implement pinging the watchdog: counter ID 1 is
29  * set to restart counting from initial value on counter ID 0 end count event.
30  * Pinging is done by forcing immediate end count event on counter ID 0.
31  * If only one counter was used, pinging would have to be implemented by
32  * disabling and enabling the counter, leaving the system in a vulnerable state
33  * for a (really) short period of time.
34  *
35  * Counters ID 2 and 3 are enabled by default even before U-Boot loads,
36  * therefore this driver does not provide a way to use them, eg. by setting a
37  * property in device tree.
38  */
39 
40 #define CNTR_ID_RETRIGGER		0
41 #define CNTR_ID_WDOG			1
42 
43 /* relative to cpu_misc */
44 #define WDT_TIMER_SELECT		0x64
45 #define WDT_TIMER_SELECT_MASK		0xf
46 #define WDT_TIMER_SELECT_VAL		BIT(CNTR_ID_WDOG)
47 
48 /* relative to reg */
49 #define CNTR_CTRL(id)			((id) * 0x10)
50 #define CNTR_CTRL_ENABLE		0x0001
51 #define CNTR_CTRL_ACTIVE		0x0002
52 #define CNTR_CTRL_MODE_MASK		0x000c
53 #define CNTR_CTRL_MODE_ONESHOT		0x0000
54 #define CNTR_CTRL_MODE_HWSIG		0x000c
55 #define CNTR_CTRL_TRIG_SRC_MASK		0x00f0
56 #define CNTR_CTRL_TRIG_SRC_PREV_CNTR	0x0050
57 #define CNTR_CTRL_PRESCALE_MASK		0xff00
58 #define CNTR_CTRL_PRESCALE_MIN		2
59 #define CNTR_CTRL_PRESCALE_SHIFT	8
60 
61 #define CNTR_COUNT_LOW(id)		(CNTR_CTRL(id) + 0x4)
62 #define CNTR_COUNT_HIGH(id)		(CNTR_CTRL(id) + 0x8)
63 
64 #define WATCHDOG_TIMEOUT		120
65 
66 static unsigned int timeout;
67 module_param(timeout, int, 0);
68 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
69 
70 static bool nowayout = WATCHDOG_NOWAYOUT;
71 module_param(nowayout, bool, 0);
72 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
73 			   __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
74 
75 struct armada_37xx_watchdog {
76 	struct watchdog_device wdt;
77 	struct regmap *cpu_misc;
78 	void __iomem *reg;
79 	u64 timeout; /* in clock ticks */
80 	unsigned long clk_rate;
81 	struct clk *clk;
82 };
83 
get_counter_value(struct armada_37xx_watchdog * dev,int id)84 static u64 get_counter_value(struct armada_37xx_watchdog *dev, int id)
85 {
86 	u64 val;
87 
88 	/*
89 	 * when low is read, high is latched into flip-flops so that it can be
90 	 * read consistently without using software debouncing
91 	 */
92 	val = readl(dev->reg + CNTR_COUNT_LOW(id));
93 	val |= ((u64)readl(dev->reg + CNTR_COUNT_HIGH(id))) << 32;
94 
95 	return val;
96 }
97 
set_counter_value(struct armada_37xx_watchdog * dev,int id,u64 val)98 static void set_counter_value(struct armada_37xx_watchdog *dev, int id, u64 val)
99 {
100 	writel(val & 0xffffffff, dev->reg + CNTR_COUNT_LOW(id));
101 	writel(val >> 32, dev->reg + CNTR_COUNT_HIGH(id));
102 }
103 
counter_enable(struct armada_37xx_watchdog * dev,int id)104 static void counter_enable(struct armada_37xx_watchdog *dev, int id)
105 {
106 	u32 reg;
107 
108 	reg = readl(dev->reg + CNTR_CTRL(id));
109 	reg |= CNTR_CTRL_ENABLE;
110 	writel(reg, dev->reg + CNTR_CTRL(id));
111 }
112 
counter_disable(struct armada_37xx_watchdog * dev,int id)113 static void counter_disable(struct armada_37xx_watchdog *dev, int id)
114 {
115 	u32 reg;
116 
117 	reg = readl(dev->reg + CNTR_CTRL(id));
118 	reg &= ~CNTR_CTRL_ENABLE;
119 	writel(reg, dev->reg + CNTR_CTRL(id));
120 }
121 
init_counter(struct armada_37xx_watchdog * dev,int id,u32 mode,u32 trig_src)122 static void init_counter(struct armada_37xx_watchdog *dev, int id, u32 mode,
123 			 u32 trig_src)
124 {
125 	u32 reg;
126 
127 	reg = readl(dev->reg + CNTR_CTRL(id));
128 
129 	reg &= ~(CNTR_CTRL_MODE_MASK | CNTR_CTRL_PRESCALE_MASK |
130 		 CNTR_CTRL_TRIG_SRC_MASK);
131 
132 	/* set mode */
133 	reg |= mode & CNTR_CTRL_MODE_MASK;
134 
135 	/* set prescaler to the min value */
136 	reg |= CNTR_CTRL_PRESCALE_MIN << CNTR_CTRL_PRESCALE_SHIFT;
137 
138 	/* set trigger source */
139 	reg |= trig_src & CNTR_CTRL_TRIG_SRC_MASK;
140 
141 	writel(reg, dev->reg + CNTR_CTRL(id));
142 }
143 
armada_37xx_wdt_ping(struct watchdog_device * wdt)144 static int armada_37xx_wdt_ping(struct watchdog_device *wdt)
145 {
146 	struct armada_37xx_watchdog *dev = watchdog_get_drvdata(wdt);
147 
148 	/* counter 1 is retriggered by forcing end count on counter 0 */
149 	counter_disable(dev, CNTR_ID_RETRIGGER);
150 	counter_enable(dev, CNTR_ID_RETRIGGER);
151 
152 	return 0;
153 }
154 
armada_37xx_wdt_get_timeleft(struct watchdog_device * wdt)155 static unsigned int armada_37xx_wdt_get_timeleft(struct watchdog_device *wdt)
156 {
157 	struct armada_37xx_watchdog *dev = watchdog_get_drvdata(wdt);
158 	u64 res;
159 
160 	res = get_counter_value(dev, CNTR_ID_WDOG) * CNTR_CTRL_PRESCALE_MIN;
161 	do_div(res, dev->clk_rate);
162 
163 	return res;
164 }
165 
armada_37xx_wdt_set_timeout(struct watchdog_device * wdt,unsigned int timeout)166 static int armada_37xx_wdt_set_timeout(struct watchdog_device *wdt,
167 				       unsigned int timeout)
168 {
169 	struct armada_37xx_watchdog *dev = watchdog_get_drvdata(wdt);
170 
171 	wdt->timeout = timeout;
172 
173 	/*
174 	 * Compute the timeout in clock rate. We use smallest possible
175 	 * prescaler, which divides the clock rate by 2
176 	 * (CNTR_CTRL_PRESCALE_MIN).
177 	 */
178 	dev->timeout = (u64)dev->clk_rate * timeout;
179 	do_div(dev->timeout, CNTR_CTRL_PRESCALE_MIN);
180 
181 	set_counter_value(dev, CNTR_ID_WDOG, dev->timeout);
182 
183 	return 0;
184 }
185 
armada_37xx_wdt_is_running(struct armada_37xx_watchdog * dev)186 static bool armada_37xx_wdt_is_running(struct armada_37xx_watchdog *dev)
187 {
188 	u32 reg;
189 
190 	regmap_read(dev->cpu_misc, WDT_TIMER_SELECT, &reg);
191 	if ((reg & WDT_TIMER_SELECT_MASK) != WDT_TIMER_SELECT_VAL)
192 		return false;
193 
194 	reg = readl(dev->reg + CNTR_CTRL(CNTR_ID_WDOG));
195 	return !!(reg & CNTR_CTRL_ACTIVE);
196 }
197 
armada_37xx_wdt_start(struct watchdog_device * wdt)198 static int armada_37xx_wdt_start(struct watchdog_device *wdt)
199 {
200 	struct armada_37xx_watchdog *dev = watchdog_get_drvdata(wdt);
201 
202 	/* select counter 1 as watchdog counter */
203 	regmap_write(dev->cpu_misc, WDT_TIMER_SELECT, WDT_TIMER_SELECT_VAL);
204 
205 	/* init counter 0 as retrigger counter for counter 1 */
206 	init_counter(dev, CNTR_ID_RETRIGGER, CNTR_CTRL_MODE_ONESHOT, 0);
207 	set_counter_value(dev, CNTR_ID_RETRIGGER, 0);
208 
209 	/* init counter 1 to be retriggerable by counter 0 end count */
210 	init_counter(dev, CNTR_ID_WDOG, CNTR_CTRL_MODE_HWSIG,
211 		     CNTR_CTRL_TRIG_SRC_PREV_CNTR);
212 	set_counter_value(dev, CNTR_ID_WDOG, dev->timeout);
213 
214 	/* enable counter 1 */
215 	counter_enable(dev, CNTR_ID_WDOG);
216 
217 	/* start counter 1 by forcing immediate end count on counter 0 */
218 	counter_enable(dev, CNTR_ID_RETRIGGER);
219 
220 	return 0;
221 }
222 
armada_37xx_wdt_stop(struct watchdog_device * wdt)223 static int armada_37xx_wdt_stop(struct watchdog_device *wdt)
224 {
225 	struct armada_37xx_watchdog *dev = watchdog_get_drvdata(wdt);
226 
227 	counter_disable(dev, CNTR_ID_WDOG);
228 	counter_disable(dev, CNTR_ID_RETRIGGER);
229 	regmap_write(dev->cpu_misc, WDT_TIMER_SELECT, 0);
230 
231 	return 0;
232 }
233 
234 static const struct watchdog_info armada_37xx_wdt_info = {
235 	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
236 	.identity = "Armada 37xx Watchdog",
237 };
238 
239 static const struct watchdog_ops armada_37xx_wdt_ops = {
240 	.owner = THIS_MODULE,
241 	.start = armada_37xx_wdt_start,
242 	.stop = armada_37xx_wdt_stop,
243 	.ping = armada_37xx_wdt_ping,
244 	.set_timeout = armada_37xx_wdt_set_timeout,
245 	.get_timeleft = armada_37xx_wdt_get_timeleft,
246 };
247 
armada_37xx_wdt_probe(struct platform_device * pdev)248 static int armada_37xx_wdt_probe(struct platform_device *pdev)
249 {
250 	struct armada_37xx_watchdog *dev;
251 	struct resource *res;
252 	struct regmap *regmap;
253 	int ret;
254 
255 	dev = devm_kzalloc(&pdev->dev, sizeof(struct armada_37xx_watchdog),
256 			   GFP_KERNEL);
257 	if (!dev)
258 		return -ENOMEM;
259 
260 	dev->wdt.info = &armada_37xx_wdt_info;
261 	dev->wdt.ops = &armada_37xx_wdt_ops;
262 
263 	regmap = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
264 						 "marvell,system-controller");
265 	if (IS_ERR(regmap))
266 		return PTR_ERR(regmap);
267 	dev->cpu_misc = regmap;
268 
269 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
270 	if (!res)
271 		return -ENODEV;
272 	dev->reg = devm_ioremap(&pdev->dev, res->start, resource_size(res));
273 	if (!dev->reg)
274 		return -ENOMEM;
275 
276 	/* init clock */
277 	dev->clk = devm_clk_get_enabled(&pdev->dev, NULL);
278 	if (IS_ERR(dev->clk))
279 		return PTR_ERR(dev->clk);
280 
281 	dev->clk_rate = clk_get_rate(dev->clk);
282 	if (!dev->clk_rate)
283 		return -EINVAL;
284 
285 	/*
286 	 * Since the timeout in seconds is given as 32 bit unsigned int, and
287 	 * the counters hold 64 bit values, even after multiplication by clock
288 	 * rate the counter can hold timeout of UINT_MAX seconds.
289 	 */
290 	dev->wdt.min_timeout = 1;
291 	dev->wdt.max_timeout = UINT_MAX;
292 	dev->wdt.parent = &pdev->dev;
293 
294 	/* default value, possibly override by module parameter or dtb */
295 	dev->wdt.timeout = WATCHDOG_TIMEOUT;
296 	watchdog_init_timeout(&dev->wdt, timeout, &pdev->dev);
297 
298 	platform_set_drvdata(pdev, &dev->wdt);
299 	watchdog_set_drvdata(&dev->wdt, dev);
300 
301 	armada_37xx_wdt_set_timeout(&dev->wdt, dev->wdt.timeout);
302 
303 	if (armada_37xx_wdt_is_running(dev))
304 		set_bit(WDOG_HW_RUNNING, &dev->wdt.status);
305 
306 	watchdog_set_nowayout(&dev->wdt, nowayout);
307 	watchdog_stop_on_reboot(&dev->wdt);
308 	ret = devm_watchdog_register_device(&pdev->dev, &dev->wdt);
309 	if (ret)
310 		return ret;
311 
312 	dev_info(&pdev->dev, "Initial timeout %d sec%s\n",
313 		 dev->wdt.timeout, nowayout ? ", nowayout" : "");
314 
315 	return 0;
316 }
317 
armada_37xx_wdt_suspend(struct device * dev)318 static int __maybe_unused armada_37xx_wdt_suspend(struct device *dev)
319 {
320 	struct watchdog_device *wdt = dev_get_drvdata(dev);
321 
322 	return armada_37xx_wdt_stop(wdt);
323 }
324 
armada_37xx_wdt_resume(struct device * dev)325 static int __maybe_unused armada_37xx_wdt_resume(struct device *dev)
326 {
327 	struct watchdog_device *wdt = dev_get_drvdata(dev);
328 
329 	if (watchdog_active(wdt))
330 		return armada_37xx_wdt_start(wdt);
331 
332 	return 0;
333 }
334 
335 static const struct dev_pm_ops armada_37xx_wdt_dev_pm_ops = {
336 	SET_SYSTEM_SLEEP_PM_OPS(armada_37xx_wdt_suspend,
337 				armada_37xx_wdt_resume)
338 };
339 
340 #ifdef CONFIG_OF
341 static const struct of_device_id armada_37xx_wdt_match[] = {
342 	{ .compatible = "marvell,armada-3700-wdt", },
343 	{},
344 };
345 MODULE_DEVICE_TABLE(of, armada_37xx_wdt_match);
346 #endif
347 
348 static struct platform_driver armada_37xx_wdt_driver = {
349 	.probe		= armada_37xx_wdt_probe,
350 	.driver		= {
351 		.name	= "armada_37xx_wdt",
352 		.of_match_table = of_match_ptr(armada_37xx_wdt_match),
353 		.pm = &armada_37xx_wdt_dev_pm_ops,
354 	},
355 };
356 
357 module_platform_driver(armada_37xx_wdt_driver);
358 
359 MODULE_AUTHOR("Marek Behun <kabel@kernel.org>");
360 MODULE_DESCRIPTION("Armada 37xx CPU Watchdog");
361 
362 MODULE_LICENSE("GPL v2");
363 MODULE_ALIAS("platform:armada_37xx_wdt");
364