1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Watchdog driver for Intel Keem Bay non-secure watchdog.
4  *
5  * Copyright (C) 2020 Intel Corporation
6  */
7 
8 #include <linux/arm-smccc.h>
9 #include <linux/bits.h>
10 #include <linux/clk.h>
11 #include <linux/interrupt.h>
12 #include <linux/io.h>
13 #include <linux/limits.h>
14 #include <linux/module.h>
15 #include <linux/mod_devicetable.h>
16 #include <linux/platform_device.h>
17 #include <linux/reboot.h>
18 #include <linux/watchdog.h>
19 
20 /* Non-secure watchdog register offsets */
21 #define TIM_WATCHDOG		0x0
22 #define TIM_WATCHDOG_INT_THRES	0x4
23 #define TIM_WDOG_EN		0x8
24 #define TIM_SAFE		0xc
25 
26 #define WDT_TH_INT_MASK		BIT(8)
27 #define WDT_TO_INT_MASK		BIT(9)
28 #define WDT_INT_CLEAR_SMC	0x8200ff18
29 
30 #define WDT_UNLOCK		0xf1d0dead
31 #define WDT_DISABLE		0x0
32 #define WDT_ENABLE		0x1
33 
34 #define WDT_LOAD_MAX		U32_MAX
35 #define WDT_LOAD_MIN		1
36 
37 #define WDT_TIMEOUT		5
38 #define WDT_PRETIMEOUT		4
39 
40 static unsigned int timeout = WDT_TIMEOUT;
41 module_param(timeout, int, 0);
42 MODULE_PARM_DESC(timeout, "Watchdog timeout period in seconds (default = "
43 		 __MODULE_STRING(WDT_TIMEOUT) ")");
44 
45 static bool nowayout = WATCHDOG_NOWAYOUT;
46 module_param(nowayout, bool, 0);
47 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default = "
48 		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
49 
50 struct keembay_wdt {
51 	struct watchdog_device	wdd;
52 	struct clk		*clk;
53 	unsigned int		rate;
54 	int			to_irq;
55 	int			th_irq;
56 	void __iomem		*base;
57 };
58 
59 static inline u32 keembay_wdt_readl(struct keembay_wdt *wdt, u32 offset)
60 {
61 	return readl(wdt->base + offset);
62 }
63 
64 static inline void keembay_wdt_writel(struct keembay_wdt *wdt, u32 offset, u32 val)
65 {
66 	writel(WDT_UNLOCK, wdt->base + TIM_SAFE);
67 	writel(val, wdt->base + offset);
68 }
69 
70 static void keembay_wdt_set_timeout_reg(struct watchdog_device *wdog)
71 {
72 	struct keembay_wdt *wdt = watchdog_get_drvdata(wdog);
73 
74 	keembay_wdt_writel(wdt, TIM_WATCHDOG, wdog->timeout * wdt->rate);
75 }
76 
77 static void keembay_wdt_set_pretimeout_reg(struct watchdog_device *wdog)
78 {
79 	struct keembay_wdt *wdt = watchdog_get_drvdata(wdog);
80 	u32 th_val = 0;
81 
82 	if (wdog->pretimeout)
83 		th_val = wdog->timeout - wdog->pretimeout;
84 
85 	keembay_wdt_writel(wdt, TIM_WATCHDOG_INT_THRES, th_val * wdt->rate);
86 }
87 
88 static int keembay_wdt_start(struct watchdog_device *wdog)
89 {
90 	struct keembay_wdt *wdt = watchdog_get_drvdata(wdog);
91 
92 	keembay_wdt_writel(wdt, TIM_WDOG_EN, WDT_ENABLE);
93 
94 	return 0;
95 }
96 
97 static int keembay_wdt_stop(struct watchdog_device *wdog)
98 {
99 	struct keembay_wdt *wdt = watchdog_get_drvdata(wdog);
100 
101 	keembay_wdt_writel(wdt, TIM_WDOG_EN, WDT_DISABLE);
102 
103 	return 0;
104 }
105 
106 static int keembay_wdt_ping(struct watchdog_device *wdog)
107 {
108 	keembay_wdt_set_timeout_reg(wdog);
109 
110 	return 0;
111 }
112 
113 static int keembay_wdt_set_timeout(struct watchdog_device *wdog, u32 t)
114 {
115 	wdog->timeout = t;
116 	keembay_wdt_set_timeout_reg(wdog);
117 	keembay_wdt_set_pretimeout_reg(wdog);
118 
119 	return 0;
120 }
121 
122 static int keembay_wdt_set_pretimeout(struct watchdog_device *wdog, u32 t)
123 {
124 	if (t > wdog->timeout)
125 		return -EINVAL;
126 
127 	wdog->pretimeout = t;
128 	keembay_wdt_set_pretimeout_reg(wdog);
129 
130 	return 0;
131 }
132 
133 static unsigned int keembay_wdt_get_timeleft(struct watchdog_device *wdog)
134 {
135 	struct keembay_wdt *wdt = watchdog_get_drvdata(wdog);
136 
137 	return keembay_wdt_readl(wdt, TIM_WATCHDOG) / wdt->rate;
138 }
139 
140 /*
141  * SMC call is used to clear the interrupt bits, because the TIM_GEN_CONFIG
142  * register is in the secure bank.
143  */
144 static irqreturn_t keembay_wdt_to_isr(int irq, void *dev_id)
145 {
146 	struct keembay_wdt *wdt = dev_id;
147 	struct arm_smccc_res res;
148 
149 	arm_smccc_smc(WDT_INT_CLEAR_SMC, WDT_TO_INT_MASK, 0, 0, 0, 0, 0, 0, &res);
150 	dev_crit(wdt->wdd.parent, "Intel Keem Bay non-secure wdt timeout.\n");
151 	emergency_restart();
152 
153 	return IRQ_HANDLED;
154 }
155 
156 static irqreturn_t keembay_wdt_th_isr(int irq, void *dev_id)
157 {
158 	struct keembay_wdt *wdt = dev_id;
159 	struct arm_smccc_res res;
160 
161 	keembay_wdt_set_pretimeout(&wdt->wdd, 0x0);
162 
163 	arm_smccc_smc(WDT_INT_CLEAR_SMC, WDT_TH_INT_MASK, 0, 0, 0, 0, 0, 0, &res);
164 	dev_crit(wdt->wdd.parent, "Intel Keem Bay non-secure wdt pre-timeout.\n");
165 	watchdog_notify_pretimeout(&wdt->wdd);
166 
167 	return IRQ_HANDLED;
168 }
169 
170 static const struct watchdog_info keembay_wdt_info = {
171 	.identity	= "Intel Keem Bay Watchdog Timer",
172 	.options	= WDIOF_SETTIMEOUT |
173 			  WDIOF_PRETIMEOUT |
174 			  WDIOF_MAGICCLOSE |
175 			  WDIOF_KEEPALIVEPING,
176 };
177 
178 static const struct watchdog_ops keembay_wdt_ops = {
179 	.owner		= THIS_MODULE,
180 	.start		= keembay_wdt_start,
181 	.stop		= keembay_wdt_stop,
182 	.ping		= keembay_wdt_ping,
183 	.set_timeout	= keembay_wdt_set_timeout,
184 	.set_pretimeout	= keembay_wdt_set_pretimeout,
185 	.get_timeleft	= keembay_wdt_get_timeleft,
186 };
187 
188 static int keembay_wdt_probe(struct platform_device *pdev)
189 {
190 	struct device *dev = &pdev->dev;
191 	struct keembay_wdt *wdt;
192 	int ret;
193 
194 	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
195 	if (!wdt)
196 		return -ENOMEM;
197 
198 	wdt->base = devm_platform_ioremap_resource(pdev, 0);
199 	if (IS_ERR(wdt->base))
200 		return PTR_ERR(wdt->base);
201 
202 	/* we do not need to enable the clock as it is enabled by default */
203 	wdt->clk = devm_clk_get(dev, NULL);
204 	if (IS_ERR(wdt->clk))
205 		return dev_err_probe(dev, PTR_ERR(wdt->clk), "Failed to get clock\n");
206 
207 	wdt->rate = clk_get_rate(wdt->clk);
208 	if (!wdt->rate)
209 		return dev_err_probe(dev, -EINVAL, "Failed to get clock rate\n");
210 
211 	wdt->th_irq = platform_get_irq_byname(pdev, "threshold");
212 	if (wdt->th_irq < 0)
213 		return dev_err_probe(dev, wdt->th_irq, "Failed to get IRQ for threshold\n");
214 
215 	ret = devm_request_irq(dev, wdt->th_irq, keembay_wdt_th_isr, 0,
216 			       "keembay-wdt", wdt);
217 	if (ret)
218 		return dev_err_probe(dev, ret, "Failed to request IRQ for threshold\n");
219 
220 	wdt->to_irq = platform_get_irq_byname(pdev, "timeout");
221 	if (wdt->to_irq < 0)
222 		return dev_err_probe(dev, wdt->to_irq, "Failed to get IRQ for timeout\n");
223 
224 	ret = devm_request_irq(dev, wdt->to_irq, keembay_wdt_to_isr, 0,
225 			       "keembay-wdt", wdt);
226 	if (ret)
227 		return dev_err_probe(dev, ret, "Failed to request IRQ for timeout\n");
228 
229 	wdt->wdd.parent		= dev;
230 	wdt->wdd.info		= &keembay_wdt_info;
231 	wdt->wdd.ops		= &keembay_wdt_ops;
232 	wdt->wdd.min_timeout	= WDT_LOAD_MIN;
233 	wdt->wdd.max_timeout	= WDT_LOAD_MAX / wdt->rate;
234 	wdt->wdd.timeout	= WDT_TIMEOUT;
235 	wdt->wdd.pretimeout	= WDT_PRETIMEOUT;
236 
237 	watchdog_set_drvdata(&wdt->wdd, wdt);
238 	watchdog_set_nowayout(&wdt->wdd, nowayout);
239 	watchdog_init_timeout(&wdt->wdd, timeout, dev);
240 	keembay_wdt_set_timeout(&wdt->wdd, wdt->wdd.timeout);
241 	keembay_wdt_set_pretimeout(&wdt->wdd, wdt->wdd.pretimeout);
242 
243 	ret = devm_watchdog_register_device(dev, &wdt->wdd);
244 	if (ret)
245 		return dev_err_probe(dev, ret, "Failed to register watchdog device.\n");
246 
247 	platform_set_drvdata(pdev, wdt);
248 	dev_info(dev, "Initial timeout %d sec%s.\n",
249 		 wdt->wdd.timeout, nowayout ? ", nowayout" : "");
250 
251 	return 0;
252 }
253 
254 static int __maybe_unused keembay_wdt_suspend(struct device *dev)
255 {
256 	struct keembay_wdt *wdt = dev_get_drvdata(dev);
257 
258 	if (watchdog_active(&wdt->wdd))
259 		return keembay_wdt_stop(&wdt->wdd);
260 
261 	return 0;
262 }
263 
264 static int __maybe_unused keembay_wdt_resume(struct device *dev)
265 {
266 	struct keembay_wdt *wdt = dev_get_drvdata(dev);
267 
268 	if (watchdog_active(&wdt->wdd))
269 		return keembay_wdt_start(&wdt->wdd);
270 
271 	return 0;
272 }
273 
274 static SIMPLE_DEV_PM_OPS(keembay_wdt_pm_ops, keembay_wdt_suspend,
275 			 keembay_wdt_resume);
276 
277 static const struct of_device_id keembay_wdt_match[] = {
278 	{ .compatible = "intel,keembay-wdt" },
279 	{ }
280 };
281 MODULE_DEVICE_TABLE(of, keembay_wdt_match);
282 
283 static struct platform_driver keembay_wdt_driver = {
284 	.probe	= keembay_wdt_probe,
285 	.driver	= {
286 		.name		= "keembay_wdt",
287 		.of_match_table	= keembay_wdt_match,
288 		.pm		= &keembay_wdt_pm_ops,
289 	},
290 };
291 
292 module_platform_driver(keembay_wdt_driver);
293 
294 MODULE_DESCRIPTION("Intel Keem Bay SoC watchdog driver");
295 MODULE_AUTHOR("Wan Ahmad Zainie <wan.ahmad.zainie.wan.mohamad@intel.com");
296 MODULE_LICENSE("GPL v2");
297