xref: /openbmc/linux/drivers/watchdog/bd9576_wdt.c (revision e5bd61e8)
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/of.h>
13 #include <linux/platform_device.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 	bool			always_running;
33 	struct watchdog_device	wdd;
34 };
35 
36 static void bd9576_wdt_disable(struct bd9576_wdt_priv *priv)
37 {
38 	gpiod_set_value_cansleep(priv->gpiod_en, 0);
39 }
40 
41 static int bd9576_wdt_ping(struct watchdog_device *wdd)
42 {
43 	struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
44 
45 	/* Pulse */
46 	gpiod_set_value_cansleep(priv->gpiod_ping, 1);
47 	gpiod_set_value_cansleep(priv->gpiod_ping, 0);
48 
49 	return 0;
50 }
51 
52 static int bd9576_wdt_start(struct watchdog_device *wdd)
53 {
54 	struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
55 
56 	gpiod_set_value_cansleep(priv->gpiod_en, 1);
57 
58 	return bd9576_wdt_ping(wdd);
59 }
60 
61 static int bd9576_wdt_stop(struct watchdog_device *wdd)
62 {
63 	struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
64 
65 	if (!priv->always_running)
66 		bd9576_wdt_disable(priv);
67 	else
68 		set_bit(WDOG_HW_RUNNING, &wdd->status);
69 
70 	return 0;
71 }
72 
73 static const struct watchdog_info bd957x_wdt_ident = {
74 	.options	= WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
75 			  WDIOF_SETTIMEOUT,
76 	.identity	= "BD957x Watchdog",
77 };
78 
79 static const struct watchdog_ops bd957x_wdt_ops = {
80 	.owner		= THIS_MODULE,
81 	.start		= bd9576_wdt_start,
82 	.stop		= bd9576_wdt_stop,
83 	.ping		= bd9576_wdt_ping,
84 };
85 
86 /* Unit is hundreds of uS */
87 #define FASTNG_MIN 23
88 
89 static int find_closest_fast(int target, int *sel, int *val)
90 {
91 	int i;
92 	int window = FASTNG_MIN;
93 
94 	for (i = 0; i < 8 && window < target; i++)
95 		window <<= 1;
96 
97 	*val = window;
98 	*sel = i;
99 
100 	if (i == 8)
101 		return -EINVAL;
102 
103 	return 0;
104 
105 }
106 
107 static int find_closest_slow_by_fast(int fast_val, int target, int *slowsel)
108 {
109 	int sel;
110 	static const int multipliers[] = {2, 3, 7, 15};
111 
112 	for (sel = 0; sel < ARRAY_SIZE(multipliers) &&
113 	     multipliers[sel] * fast_val < target; sel++)
114 		;
115 
116 	if (sel == ARRAY_SIZE(multipliers))
117 		return -EINVAL;
118 
119 	*slowsel = sel;
120 
121 	return 0;
122 }
123 
124 static int find_closest_slow(int target, int *slow_sel, int *fast_sel)
125 {
126 	static const int multipliers[] = {2, 3, 7, 15};
127 	int i, j;
128 	int val = 0;
129 	int window = FASTNG_MIN;
130 
131 	for (i = 0; i < 8; i++) {
132 		for (j = 0; j < ARRAY_SIZE(multipliers); j++) {
133 			int slow;
134 
135 			slow = window * multipliers[j];
136 			if (slow >= target && (!val || slow < val)) {
137 				val = slow;
138 				*fast_sel = i;
139 				*slow_sel = j;
140 			}
141 		}
142 		window <<= 1;
143 	}
144 	if (!val)
145 		return -EINVAL;
146 
147 	return 0;
148 }
149 
150 #define BD957X_WDG_TYPE_WINDOW BIT(5)
151 #define BD957X_WDG_TYPE_SLOW 0
152 #define BD957X_WDG_TYPE_MASK BIT(5)
153 #define BD957X_WDG_NG_RATIO_MASK 0x18
154 #define BD957X_WDG_FASTNG_MASK 0x7
155 
156 static int bd957x_set_wdt_mode(struct bd9576_wdt_priv *priv, int hw_margin,
157 			       int hw_margin_min)
158 {
159 	int ret, fastng, slowng, type, reg, mask;
160 	struct device *dev = priv->dev;
161 
162 	/* convert to 100uS */
163 	hw_margin *= 10;
164 	hw_margin_min *= 10;
165 	if (hw_margin_min) {
166 		int min;
167 
168 		type = BD957X_WDG_TYPE_WINDOW;
169 		dev_dbg(dev, "Setting type WINDOW 0x%x\n", type);
170 		ret = find_closest_fast(hw_margin_min, &fastng, &min);
171 		if (ret) {
172 			dev_err(dev, "bad WDT window for fast timeout\n");
173 			return ret;
174 		}
175 
176 		ret = find_closest_slow_by_fast(min, hw_margin, &slowng);
177 		if (ret) {
178 			dev_err(dev, "bad WDT window\n");
179 			return ret;
180 		}
181 
182 	} else {
183 		type = BD957X_WDG_TYPE_SLOW;
184 		dev_dbg(dev, "Setting type SLOW 0x%x\n", type);
185 		ret = find_closest_slow(hw_margin, &slowng, &fastng);
186 		if (ret) {
187 			dev_err(dev, "bad WDT window\n");
188 			return ret;
189 		}
190 	}
191 
192 	slowng <<= ffs(BD957X_WDG_NG_RATIO_MASK) - 1;
193 	reg = type | slowng | fastng;
194 	mask = BD957X_WDG_TYPE_MASK | BD957X_WDG_NG_RATIO_MASK |
195 	       BD957X_WDG_FASTNG_MASK;
196 	ret = regmap_update_bits(priv->regmap, BD957X_REG_WDT_CONF,
197 				 mask, reg);
198 
199 	return ret;
200 }
201 
202 static int bd9576_wdt_probe(struct platform_device *pdev)
203 {
204 	struct device *dev = &pdev->dev;
205 	struct device_node *np = dev->parent->of_node;
206 	struct bd9576_wdt_priv *priv;
207 	u32 hw_margin[2];
208 	u32 hw_margin_max = BD957X_WDT_DEFAULT_MARGIN, hw_margin_min = 0;
209 	int ret;
210 
211 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
212 	if (!priv)
213 		return -ENOMEM;
214 
215 	platform_set_drvdata(pdev, priv);
216 
217 	priv->dev = dev;
218 	priv->regmap = dev_get_regmap(dev->parent, NULL);
219 	if (!priv->regmap) {
220 		dev_err(dev, "No regmap found\n");
221 		return -ENODEV;
222 	}
223 
224 	priv->gpiod_en = devm_gpiod_get_from_of_node(dev, dev->parent->of_node,
225 						     "rohm,watchdog-enable-gpios",
226 						     0, GPIOD_OUT_LOW,
227 						     "watchdog-enable");
228 	if (IS_ERR(priv->gpiod_en))
229 		return dev_err_probe(dev, PTR_ERR(priv->gpiod_en),
230 			      "getting watchdog-enable GPIO failed\n");
231 
232 	priv->gpiod_ping = devm_gpiod_get_from_of_node(dev, dev->parent->of_node,
233 						     "rohm,watchdog-ping-gpios",
234 						     0, GPIOD_OUT_LOW,
235 						     "watchdog-ping");
236 	if (IS_ERR(priv->gpiod_ping))
237 		return dev_err_probe(dev, PTR_ERR(priv->gpiod_ping),
238 				     "getting watchdog-ping GPIO failed\n");
239 
240 	ret = of_property_read_variable_u32_array(np, "rohm,hw-timeout-ms",
241 						  &hw_margin[0], 1, 2);
242 	if (ret < 0 && ret != -EINVAL)
243 		return ret;
244 
245 	if (ret == 1)
246 		hw_margin_max = hw_margin[0];
247 
248 	if (ret == 2) {
249 		hw_margin_max = hw_margin[1];
250 		hw_margin_min = hw_margin[0];
251 	}
252 
253 	ret = bd957x_set_wdt_mode(priv, hw_margin_max, hw_margin_min);
254 	if (ret)
255 		return ret;
256 
257 	priv->always_running = of_property_read_bool(np, "always-running");
258 
259 	watchdog_set_drvdata(&priv->wdd, priv);
260 
261 	priv->wdd.info			= &bd957x_wdt_ident;
262 	priv->wdd.ops			= &bd957x_wdt_ops;
263 	priv->wdd.min_hw_heartbeat_ms	= hw_margin_min;
264 	priv->wdd.max_hw_heartbeat_ms	= hw_margin_max;
265 	priv->wdd.parent		= dev;
266 	priv->wdd.timeout		= WATCHDOG_TIMEOUT;
267 
268 	watchdog_init_timeout(&priv->wdd, 0, dev);
269 	watchdog_set_nowayout(&priv->wdd, nowayout);
270 
271 	watchdog_stop_on_reboot(&priv->wdd);
272 
273 	if (priv->always_running)
274 		bd9576_wdt_start(&priv->wdd);
275 
276 	return devm_watchdog_register_device(dev, &priv->wdd);
277 }
278 
279 static struct platform_driver bd9576_wdt_driver = {
280 	.driver	= {
281 		.name = "bd9576-wdt",
282 	},
283 	.probe	= bd9576_wdt_probe,
284 };
285 
286 module_platform_driver(bd9576_wdt_driver);
287 
288 MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>");
289 MODULE_DESCRIPTION("ROHM BD9576/BD9573 Watchdog driver");
290 MODULE_LICENSE("GPL");
291 MODULE_ALIAS("platform:bd9576-wdt");
292