bd9576_wdt.c

  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	struct watchdog_device	wdd;
 33};
 34
 35static void bd9576_wdt_disable(struct bd9576_wdt_priv *priv)
 36{
 37	gpiod_set_value_cansleep(priv->gpiod_en, 0);
 38}
 39
 40static 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
 51static 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
 60static 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
 69static const struct watchdog_info bd957x_wdt_ident = {
 70	.options	= WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
 71			  WDIOF_SETTIMEOUT,
 72	.identity	= "BD957x Watchdog",
 73};
 74
 75static 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
 85static 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
103static 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
120static 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
152static 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
198static 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
280static struct platform_driver bd9576_wdt_driver = {
281	.driver	= {
282		.name = "bd9576-wdt",
283	},
284	.probe	= bd9576_wdt_probe,
285};
286
287module_platform_driver(bd9576_wdt_driver);
288
289MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>");
290MODULE_DESCRIPTION("ROHM BD9576/BD9573 Watchdog driver");
291MODULE_LICENSE("GPL");
292MODULE_ALIAS("platform:bd9576-wdt");