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
bd9576_wdt_disable(struct bd9576_wdt_priv * priv)36 static void bd9576_wdt_disable(struct bd9576_wdt_priv *priv)
37 {
38 gpiod_set_value_cansleep(priv->gpiod_en, 0);
39 }
40
bd9576_wdt_ping(struct watchdog_device * wdd)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
bd9576_wdt_start(struct watchdog_device * wdd)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
bd9576_wdt_stop(struct watchdog_device * wdd)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
find_closest_fast(int target,int * sel,int * val)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
find_closest_slow_by_fast(int fast_val,int target,int * slowsel)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
find_closest_slow(int target,int * slow_sel,int * fast_sel)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
bd957x_set_wdt_mode(struct bd9576_wdt_priv * priv,int hw_margin,int hw_margin_min)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
bd9576_wdt_probe(struct platform_device * pdev)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
