1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * ST's LPC Watchdog
4 *
5 * Copyright (C) 2014 STMicroelectronics -- All Rights Reserved
6 *
7 * Author: David Paris <david.paris@st.com> for STMicroelectronics
8 * Lee Jones <lee.jones@linaro.org> for STMicroelectronics
9 */
10
11 #include <linux/clk.h>
12 #include <linux/init.h>
13 #include <linux/io.h>
14 #include <linux/kernel.h>
15 #include <linux/mfd/syscon.h>
16 #include <linux/module.h>
17 #include <linux/of.h>
18 #include <linux/of_platform.h>
19 #include <linux/platform_device.h>
20 #include <linux/regmap.h>
21 #include <linux/watchdog.h>
22
23 #include <dt-bindings/mfd/st-lpc.h>
24
25 /* Low Power Alarm */
26 #define LPC_LPA_LSB_OFF 0x410
27 #define LPC_LPA_START_OFF 0x418
28
29 /* LPC as WDT */
30 #define LPC_WDT_OFF 0x510
31
32 static struct watchdog_device st_wdog_dev;
33
34 struct st_wdog_syscfg {
35 unsigned int reset_type_reg;
36 unsigned int reset_type_mask;
37 unsigned int enable_reg;
38 unsigned int enable_mask;
39 };
40
41 struct st_wdog {
42 void __iomem *base;
43 struct device *dev;
44 struct regmap *regmap;
45 struct st_wdog_syscfg *syscfg;
46 struct clk *clk;
47 unsigned long clkrate;
48 bool warm_reset;
49 };
50
51 static struct st_wdog_syscfg stih407_syscfg = {
52 .enable_reg = 0x204,
53 .enable_mask = BIT(19),
54 };
55
56 static const struct of_device_id st_wdog_match[] = {
57 {
58 .compatible = "st,stih407-lpc",
59 .data = &stih407_syscfg,
60 },
61 {},
62 };
63 MODULE_DEVICE_TABLE(of, st_wdog_match);
64
st_wdog_setup(struct st_wdog * st_wdog,bool enable)65 static void st_wdog_setup(struct st_wdog *st_wdog, bool enable)
66 {
67 /* Type of watchdog reset - 0: Cold 1: Warm */
68 if (st_wdog->syscfg->reset_type_reg)
69 regmap_update_bits(st_wdog->regmap,
70 st_wdog->syscfg->reset_type_reg,
71 st_wdog->syscfg->reset_type_mask,
72 st_wdog->warm_reset);
73
74 /* Mask/unmask watchdog reset */
75 regmap_update_bits(st_wdog->regmap,
76 st_wdog->syscfg->enable_reg,
77 st_wdog->syscfg->enable_mask,
78 enable ? 0 : st_wdog->syscfg->enable_mask);
79 }
80
st_wdog_load_timer(struct st_wdog * st_wdog,unsigned int timeout)81 static void st_wdog_load_timer(struct st_wdog *st_wdog, unsigned int timeout)
82 {
83 unsigned long clkrate = st_wdog->clkrate;
84
85 writel_relaxed(timeout * clkrate, st_wdog->base + LPC_LPA_LSB_OFF);
86 writel_relaxed(1, st_wdog->base + LPC_LPA_START_OFF);
87 }
88
st_wdog_start(struct watchdog_device * wdd)89 static int st_wdog_start(struct watchdog_device *wdd)
90 {
91 struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
92
93 writel_relaxed(1, st_wdog->base + LPC_WDT_OFF);
94
95 return 0;
96 }
97
st_wdog_stop(struct watchdog_device * wdd)98 static int st_wdog_stop(struct watchdog_device *wdd)
99 {
100 struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
101
102 writel_relaxed(0, st_wdog->base + LPC_WDT_OFF);
103
104 return 0;
105 }
106
st_wdog_set_timeout(struct watchdog_device * wdd,unsigned int timeout)107 static int st_wdog_set_timeout(struct watchdog_device *wdd,
108 unsigned int timeout)
109 {
110 struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
111
112 wdd->timeout = timeout;
113 st_wdog_load_timer(st_wdog, timeout);
114
115 return 0;
116 }
117
st_wdog_keepalive(struct watchdog_device * wdd)118 static int st_wdog_keepalive(struct watchdog_device *wdd)
119 {
120 struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
121
122 st_wdog_load_timer(st_wdog, wdd->timeout);
123
124 return 0;
125 }
126
127 static const struct watchdog_info st_wdog_info = {
128 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
129 .identity = "ST LPC WDT",
130 };
131
132 static const struct watchdog_ops st_wdog_ops = {
133 .owner = THIS_MODULE,
134 .start = st_wdog_start,
135 .stop = st_wdog_stop,
136 .ping = st_wdog_keepalive,
137 .set_timeout = st_wdog_set_timeout,
138 };
139
140 static struct watchdog_device st_wdog_dev = {
141 .info = &st_wdog_info,
142 .ops = &st_wdog_ops,
143 };
144
st_clk_disable_unprepare(void * data)145 static void st_clk_disable_unprepare(void *data)
146 {
147 clk_disable_unprepare(data);
148 }
149
st_wdog_probe(struct platform_device * pdev)150 static int st_wdog_probe(struct platform_device *pdev)
151 {
152 struct device *dev = &pdev->dev;
153 const struct of_device_id *match;
154 struct device_node *np = dev->of_node;
155 struct st_wdog *st_wdog;
156 struct regmap *regmap;
157 struct clk *clk;
158 void __iomem *base;
159 uint32_t mode;
160 int ret;
161
162 ret = of_property_read_u32(np, "st,lpc-mode", &mode);
163 if (ret) {
164 dev_err(dev, "An LPC mode must be provided\n");
165 return -EINVAL;
166 }
167
168 /* LPC can either run as a Clocksource or in RTC or WDT mode */
169 if (mode != ST_LPC_MODE_WDT)
170 return -ENODEV;
171
172 st_wdog = devm_kzalloc(dev, sizeof(*st_wdog), GFP_KERNEL);
173 if (!st_wdog)
174 return -ENOMEM;
175
176 match = of_match_device(st_wdog_match, dev);
177 if (!match) {
178 dev_err(dev, "Couldn't match device\n");
179 return -ENODEV;
180 }
181 st_wdog->syscfg = (struct st_wdog_syscfg *)match->data;
182
183 base = devm_platform_ioremap_resource(pdev, 0);
184 if (IS_ERR(base))
185 return PTR_ERR(base);
186
187 regmap = syscon_regmap_lookup_by_phandle(np, "st,syscfg");
188 if (IS_ERR(regmap)) {
189 dev_err(dev, "No syscfg phandle specified\n");
190 return PTR_ERR(regmap);
191 }
192
193 clk = devm_clk_get(dev, NULL);
194 if (IS_ERR(clk)) {
195 dev_err(dev, "Unable to request clock\n");
196 return PTR_ERR(clk);
197 }
198
199 st_wdog->dev = dev;
200 st_wdog->base = base;
201 st_wdog->clk = clk;
202 st_wdog->regmap = regmap;
203 st_wdog->warm_reset = of_property_read_bool(np, "st,warm_reset");
204 st_wdog->clkrate = clk_get_rate(st_wdog->clk);
205
206 if (!st_wdog->clkrate) {
207 dev_err(dev, "Unable to fetch clock rate\n");
208 return -EINVAL;
209 }
210 st_wdog_dev.max_timeout = 0xFFFFFFFF / st_wdog->clkrate;
211 st_wdog_dev.parent = dev;
212
213 ret = clk_prepare_enable(clk);
214 if (ret) {
215 dev_err(dev, "Unable to enable clock\n");
216 return ret;
217 }
218 ret = devm_add_action_or_reset(dev, st_clk_disable_unprepare, clk);
219 if (ret)
220 return ret;
221
222 watchdog_set_drvdata(&st_wdog_dev, st_wdog);
223 watchdog_set_nowayout(&st_wdog_dev, WATCHDOG_NOWAYOUT);
224
225 /* Init Watchdog timeout with value in DT */
226 ret = watchdog_init_timeout(&st_wdog_dev, 0, dev);
227 if (ret)
228 return ret;
229
230 ret = devm_watchdog_register_device(dev, &st_wdog_dev);
231 if (ret)
232 return ret;
233
234 st_wdog_setup(st_wdog, true);
235
236 dev_info(dev, "LPC Watchdog driver registered, reset type is %s",
237 st_wdog->warm_reset ? "warm" : "cold");
238
239 return ret;
240 }
241
st_wdog_remove(struct platform_device * pdev)242 static void st_wdog_remove(struct platform_device *pdev)
243 {
244 struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
245
246 st_wdog_setup(st_wdog, false);
247 }
248
st_wdog_suspend(struct device * dev)249 static int st_wdog_suspend(struct device *dev)
250 {
251 struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
252
253 if (watchdog_active(&st_wdog_dev))
254 st_wdog_stop(&st_wdog_dev);
255
256 st_wdog_setup(st_wdog, false);
257
258 clk_disable(st_wdog->clk);
259
260 return 0;
261 }
262
st_wdog_resume(struct device * dev)263 static int st_wdog_resume(struct device *dev)
264 {
265 struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
266 int ret;
267
268 ret = clk_enable(st_wdog->clk);
269 if (ret) {
270 dev_err(dev, "Unable to re-enable clock\n");
271 watchdog_unregister_device(&st_wdog_dev);
272 clk_unprepare(st_wdog->clk);
273 return ret;
274 }
275
276 st_wdog_setup(st_wdog, true);
277
278 if (watchdog_active(&st_wdog_dev)) {
279 st_wdog_load_timer(st_wdog, st_wdog_dev.timeout);
280 st_wdog_start(&st_wdog_dev);
281 }
282
283 return 0;
284 }
285
286 static DEFINE_SIMPLE_DEV_PM_OPS(st_wdog_pm_ops,
287 st_wdog_suspend, st_wdog_resume);
288
289 static struct platform_driver st_wdog_driver = {
290 .driver = {
291 .name = "st-lpc-wdt",
292 .pm = pm_sleep_ptr(&st_wdog_pm_ops),
293 .of_match_table = st_wdog_match,
294 },
295 .probe = st_wdog_probe,
296 .remove_new = st_wdog_remove,
297 };
298 module_platform_driver(st_wdog_driver);
299
300 MODULE_AUTHOR("David Paris <david.paris@st.com>");
301 MODULE_DESCRIPTION("ST LPC Watchdog Driver");
302 MODULE_LICENSE("GPL");
303