xref: /openbmc/linux/drivers/watchdog/bd9576_wdt.c (revision d47f51eb)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Copyright (C) 2020 ROHM Semiconductors
4  *
5  * ROHM BD9576MUF and BD9573MUF Watchdog driver
6  */
7 
8 #include <linux/err.h>
9 #include <linux/gpio/consumer.h>
10 #include <linux/mfd/rohm-bd957x.h>
11 #include <linux/module.h>
12 #include <linux/platform_device.h>
13 #include <linux/property.h>
14 #include <linux/regmap.h>
15 #include <linux/watchdog.h>
16 
17 static bool nowayout;
18 module_param(nowayout, bool, 0);
19 MODULE_PARM_DESC(nowayout,
20 		"Watchdog cannot be stopped once started (default=\"false\")");
21 
22 #define HW_MARGIN_MIN 2
23 #define HW_MARGIN_MAX 4416
24 #define BD957X_WDT_DEFAULT_MARGIN 4416
25 #define WATCHDOG_TIMEOUT 30
26 
27 struct bd9576_wdt_priv {
28 	struct gpio_desc	*gpiod_ping;
29 	struct gpio_desc	*gpiod_en;
30 	struct device		*dev;
31 	struct regmap		*regmap;
32 	struct watchdog_device	wdd;
33 };
34 
bd9576_wdt_disable(struct bd9576_wdt_priv * priv)35 static void bd9576_wdt_disable(struct bd9576_wdt_priv *priv)
36 {
37 	gpiod_set_value_cansleep(priv->gpiod_en, 0);
38 }
39 
bd9576_wdt_ping(struct watchdog_device * wdd)40 static int bd9576_wdt_ping(struct watchdog_device *wdd)
41 {
42 	struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
43 
44 	/* Pulse */
45 	gpiod_set_value_cansleep(priv->gpiod_ping, 1);
46 	gpiod_set_value_cansleep(priv->gpiod_ping, 0);
47 
48 	return 0;
49 }
50 
bd9576_wdt_start(struct watchdog_device * wdd)51 static int bd9576_wdt_start(struct watchdog_device *wdd)
52 {
53 	struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
54 
55 	gpiod_set_value_cansleep(priv->gpiod_en, 1);
56 
57 	return bd9576_wdt_ping(wdd);
58 }
59 
bd9576_wdt_stop(struct watchdog_device * wdd)60 static int bd9576_wdt_stop(struct watchdog_device *wdd)
61 {
62 	struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
63 
64 	bd9576_wdt_disable(priv);
65 
66 	return 0;
67 }
68 
69 static const struct watchdog_info bd957x_wdt_ident = {
70 	.options	= WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
71 			  WDIOF_SETTIMEOUT,
72 	.identity	= "BD957x Watchdog",
73 };
74 
75 static const struct watchdog_ops bd957x_wdt_ops = {
76 	.owner		= THIS_MODULE,
77 	.start		= bd9576_wdt_start,
78 	.stop		= bd9576_wdt_stop,
79 	.ping		= bd9576_wdt_ping,
80 };
81 
82 /* Unit is hundreds of uS */
83 #define FASTNG_MIN 23
84 
find_closest_fast(int target,int * sel,int * val)85 static int find_closest_fast(int target, int *sel, int *val)
86 {
87 	int i;
88 	int window = FASTNG_MIN;
89 
90 	for (i = 0; i < 8 && window < target; i++)
91 		window <<= 1;
92 
93 	*val = window;
94 	*sel = i;
95 
96 	if (i == 8)
97 		return -EINVAL;
98 
99 	return 0;
100 
101 }
102 
find_closest_slow_by_fast(int fast_val,int target,int * slowsel)103 static int find_closest_slow_by_fast(int fast_val, int target, int *slowsel)
104 {
105 	int sel;
106 	static const int multipliers[] = {2, 3, 7, 15};
107 
108 	for (sel = 0; sel < ARRAY_SIZE(multipliers) &&
109 	     multipliers[sel] * fast_val < target; sel++)
110 		;
111 
112 	if (sel == ARRAY_SIZE(multipliers))
113 		return -EINVAL;
114 
115 	*slowsel = sel;
116 
117 	return 0;
118 }
119 
find_closest_slow(int target,int * slow_sel,int * fast_sel)120 static int find_closest_slow(int target, int *slow_sel, int *fast_sel)
121 {
122 	static const int multipliers[] = {2, 3, 7, 15};
123 	int i, j;
124 	int val = 0;
125 	int window = FASTNG_MIN;
126 
127 	for (i = 0; i < 8; i++) {
128 		for (j = 0; j < ARRAY_SIZE(multipliers); j++) {
129 			int slow;
130 
131 			slow = window * multipliers[j];
132 			if (slow >= target && (!val || slow < val)) {
133 				val = slow;
134 				*fast_sel = i;
135 				*slow_sel = j;
136 			}
137 		}
138 		window <<= 1;
139 	}
140 	if (!val)
141 		return -EINVAL;
142 
143 	return 0;
144 }
145 
146 #define BD957X_WDG_TYPE_WINDOW BIT(5)
147 #define BD957X_WDG_TYPE_SLOW 0
148 #define BD957X_WDG_TYPE_MASK BIT(5)
149 #define BD957X_WDG_NG_RATIO_MASK 0x18
150 #define BD957X_WDG_FASTNG_MASK 0x7
151 
bd957x_set_wdt_mode(struct bd9576_wdt_priv * priv,int hw_margin,int hw_margin_min)152 static int bd957x_set_wdt_mode(struct bd9576_wdt_priv *priv, int hw_margin,
153 			       int hw_margin_min)
154 {
155 	int ret, fastng, slowng, type, reg, mask;
156 	struct device *dev = priv->dev;
157 
158 	/* convert to 100uS */
159 	hw_margin *= 10;
160 	hw_margin_min *= 10;
161 	if (hw_margin_min) {
162 		int min;
163 
164 		type = BD957X_WDG_TYPE_WINDOW;
165 		dev_dbg(dev, "Setting type WINDOW 0x%x\n", type);
166 		ret = find_closest_fast(hw_margin_min, &fastng, &min);
167 		if (ret) {
168 			dev_err(dev, "bad WDT window for fast timeout\n");
169 			return ret;
170 		}
171 
172 		ret = find_closest_slow_by_fast(min, hw_margin, &slowng);
173 		if (ret) {
174 			dev_err(dev, "bad WDT window\n");
175 			return ret;
176 		}
177 
178 	} else {
179 		type = BD957X_WDG_TYPE_SLOW;
180 		dev_dbg(dev, "Setting type SLOW 0x%x\n", type);
181 		ret = find_closest_slow(hw_margin, &slowng, &fastng);
182 		if (ret) {
183 			dev_err(dev, "bad WDT window\n");
184 			return ret;
185 		}
186 	}
187 
188 	slowng <<= ffs(BD957X_WDG_NG_RATIO_MASK) - 1;
189 	reg = type | slowng | fastng;
190 	mask = BD957X_WDG_TYPE_MASK | BD957X_WDG_NG_RATIO_MASK |
191 	       BD957X_WDG_FASTNG_MASK;
192 	ret = regmap_update_bits(priv->regmap, BD957X_REG_WDT_CONF,
193 				 mask, reg);
194 
195 	return ret;
196 }
197 
bd9576_wdt_probe(struct platform_device * pdev)198 static int bd9576_wdt_probe(struct platform_device *pdev)
199 {
200 	struct device *dev = &pdev->dev;
201 	struct bd9576_wdt_priv *priv;
202 	u32 hw_margin[2];
203 	u32 hw_margin_max = BD957X_WDT_DEFAULT_MARGIN, hw_margin_min = 0;
204 	int count;
205 	int ret;
206 
207 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
208 	if (!priv)
209 		return -ENOMEM;
210 
211 	platform_set_drvdata(pdev, priv);
212 
213 	priv->dev = dev;
214 	priv->regmap = dev_get_regmap(dev->parent, NULL);
215 	if (!priv->regmap) {
216 		dev_err(dev, "No regmap found\n");
217 		return -ENODEV;
218 	}
219 
220 	priv->gpiod_en = devm_fwnode_gpiod_get(dev, dev_fwnode(dev->parent),
221 					       "rohm,watchdog-enable",
222 					       GPIOD_OUT_LOW,
223 					       "watchdog-enable");
224 	if (IS_ERR(priv->gpiod_en))
225 		return dev_err_probe(dev, PTR_ERR(priv->gpiod_en),
226 			      "getting watchdog-enable GPIO failed\n");
227 
228 	priv->gpiod_ping = devm_fwnode_gpiod_get(dev, dev_fwnode(dev->parent),
229 						 "rohm,watchdog-ping",
230 						 GPIOD_OUT_LOW,
231 						 "watchdog-ping");
232 	if (IS_ERR(priv->gpiod_ping))
233 		return dev_err_probe(dev, PTR_ERR(priv->gpiod_ping),
234 				     "getting watchdog-ping GPIO failed\n");
235 
236 	count = device_property_count_u32(dev->parent, "rohm,hw-timeout-ms");
237 	if (count < 0 && count != -EINVAL)
238 		return count;
239 
240 	if (count > 0) {
241 		if (count > ARRAY_SIZE(hw_margin))
242 			return -EINVAL;
243 
244 		ret = device_property_read_u32_array(dev->parent,
245 						     "rohm,hw-timeout-ms",
246 						     hw_margin, count);
247 		if (ret < 0)
248 			return ret;
249 
250 		if (count == 1)
251 			hw_margin_max = hw_margin[0];
252 
253 		if (count == 2) {
254 			hw_margin_max = hw_margin[1];
255 			hw_margin_min = hw_margin[0];
256 		}
257 	}
258 
259 	ret = bd957x_set_wdt_mode(priv, hw_margin_max, hw_margin_min);
260 	if (ret)
261 		return ret;
262 
263 	watchdog_set_drvdata(&priv->wdd, priv);
264 
265 	priv->wdd.info			= &bd957x_wdt_ident;
266 	priv->wdd.ops			= &bd957x_wdt_ops;
267 	priv->wdd.min_hw_heartbeat_ms	= hw_margin_min;
268 	priv->wdd.max_hw_heartbeat_ms	= hw_margin_max;
269 	priv->wdd.parent		= dev;
270 	priv->wdd.timeout		= WATCHDOG_TIMEOUT;
271 
272 	watchdog_init_timeout(&priv->wdd, 0, dev);
273 	watchdog_set_nowayout(&priv->wdd, nowayout);
274 
275 	watchdog_stop_on_reboot(&priv->wdd);
276 
277 	return devm_watchdog_register_device(dev, &priv->wdd);
278 }
279 
280 static struct platform_driver bd9576_wdt_driver = {
281 	.driver	= {
282 		.name = "bd9576-wdt",
283 	},
284 	.probe	= bd9576_wdt_probe,
285 };
286 
287 module_platform_driver(bd9576_wdt_driver);
288 
289 MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>");
290 MODULE_DESCRIPTION("ROHM BD9576/BD9573 Watchdog driver");
291 MODULE_LICENSE("GPL");
292 MODULE_ALIAS("platform:bd9576-wdt");
293