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