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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
17static bool nowayout;
18module_param(nowayout, bool, 0);
19MODULE_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
27struct 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
36static void bd9576_wdt_disable(struct bd9576_wdt_priv *priv)
37{
38 gpiod_set_value_cansleep(priv->gpiod_en, 0);
39}
40
41static 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
52static 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
61static 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
73static const struct watchdog_info bd957x_wdt_ident = {
74 .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
75 WDIOF_SETTIMEOUT,
76 .identity = "BD957x Watchdog",
77};
78
79static 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
89static 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
107static 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
124static 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
156static 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
202static int bd9576_wdt_probe(struct platform_device *pdev)
203{
204 struct device *dev = &pdev->dev;
205 struct bd9576_wdt_priv *priv;
206 u32 hw_margin[2];
207 u32 hw_margin_max = BD957X_WDT_DEFAULT_MARGIN, hw_margin_min = 0;
208 int count;
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_fwnode_gpiod_get(dev, dev_fwnode(dev->parent),
225 "rohm,watchdog-enable",
226 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_fwnode_gpiod_get(dev, dev_fwnode(dev->parent),
233 "rohm,watchdog-ping",
234 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 count = device_property_count_u32(dev->parent, "rohm,hw-timeout-ms");
241 if (count < 0 && count != -EINVAL)
242 return count;
243
244 if (count > 0) {
245 if (count > ARRAY_SIZE(hw_margin))
246 return -EINVAL;
247
248 ret = device_property_read_u32_array(dev->parent,
249 "rohm,hw-timeout-ms",
250 hw_margin, count);
251 if (ret < 0)
252 return ret;
253
254 if (count == 1)
255 hw_margin_max = hw_margin[0];
256
257 if (count == 2) {
258 hw_margin_max = hw_margin[1];
259 hw_margin_min = hw_margin[0];
260 }
261 }
262
263 ret = bd957x_set_wdt_mode(priv, hw_margin_max, hw_margin_min);
264 if (ret)
265 return ret;
266
267 priv->always_running = device_property_read_bool(dev->parent,
268 "always-running");
269
270 watchdog_set_drvdata(&priv->wdd, priv);
271
272 priv->wdd.info = &bd957x_wdt_ident;
273 priv->wdd.ops = &bd957x_wdt_ops;
274 priv->wdd.min_hw_heartbeat_ms = hw_margin_min;
275 priv->wdd.max_hw_heartbeat_ms = hw_margin_max;
276 priv->wdd.parent = dev;
277 priv->wdd.timeout = WATCHDOG_TIMEOUT;
278
279 watchdog_init_timeout(&priv->wdd, 0, dev);
280 watchdog_set_nowayout(&priv->wdd, nowayout);
281
282 watchdog_stop_on_reboot(&priv->wdd);
283
284 if (priv->always_running)
285 bd9576_wdt_start(&priv->wdd);
286
287 return devm_watchdog_register_device(dev, &priv->wdd);
288}
289
290static struct platform_driver bd9576_wdt_driver = {
291 .driver = {
292 .name = "bd9576-wdt",
293 },
294 .probe = bd9576_wdt_probe,
295};
296
297module_platform_driver(bd9576_wdt_driver);
298
299MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>");
300MODULE_DESCRIPTION("ROHM BD9576/BD9573 Watchdog driver");
301MODULE_LICENSE("GPL");
302MODULE_ALIAS("platform:bd9576-wdt");