xref: /openbmc/linux/drivers/watchdog/da9055_wdt.c (revision 862c13b5)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * System monitoring driver for DA9055 PMICs.
4  *
5  * Copyright(c) 2012 Dialog Semiconductor Ltd.
6  *
7  * Author: David Dajun Chen <dchen@diasemi.com>
8  *
9  */
10 
11 #include <linux/module.h>
12 #include <linux/types.h>
13 #include <linux/kernel.h>
14 #include <linux/slab.h>
15 #include <linux/platform_device.h>
16 #include <linux/watchdog.h>
17 #include <linux/delay.h>
18 
19 #include <linux/mfd/da9055/core.h>
20 #include <linux/mfd/da9055/reg.h>
21 
22 static bool nowayout = WATCHDOG_NOWAYOUT;
23 module_param(nowayout, bool, 0);
24 MODULE_PARM_DESC(nowayout,
25 		 "Watchdog cannot be stopped once started (default="
26 		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
27 
28 #define DA9055_DEF_TIMEOUT	4
29 #define DA9055_TWDMIN		256
30 
31 struct da9055_wdt_data {
32 	struct watchdog_device wdt;
33 	struct da9055 *da9055;
34 };
35 
36 static const struct {
37 	u8 reg_val;
38 	int user_time;  /* In seconds */
39 } da9055_wdt_maps[] = {
40 	{ 0, 0 },
41 	{ 1, 2 },
42 	{ 2, 4 },
43 	{ 3, 8 },
44 	{ 4, 16 },
45 	{ 5, 32 },
46 	{ 5, 33 },  /* Actual time  32.768s so included both 32s and 33s */
47 	{ 6, 65 },
48 	{ 6, 66 },  /* Actual time 65.536s so include both, 65s and 66s */
49 	{ 7, 131 },
50 };
51 
da9055_wdt_set_timeout(struct watchdog_device * wdt_dev,unsigned int timeout)52 static int da9055_wdt_set_timeout(struct watchdog_device *wdt_dev,
53 				  unsigned int timeout)
54 {
55 	struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
56 	struct da9055 *da9055 = driver_data->da9055;
57 	int ret, i;
58 
59 	for (i = 0; i < ARRAY_SIZE(da9055_wdt_maps); i++)
60 		if (da9055_wdt_maps[i].user_time == timeout)
61 			break;
62 
63 	if (i == ARRAY_SIZE(da9055_wdt_maps))
64 		ret = -EINVAL;
65 	else
66 		ret = da9055_reg_update(da9055, DA9055_REG_CONTROL_B,
67 					DA9055_TWDSCALE_MASK,
68 					da9055_wdt_maps[i].reg_val <<
69 					DA9055_TWDSCALE_SHIFT);
70 	if (ret < 0) {
71 		dev_err(da9055->dev,
72 			"Failed to update timescale bit, %d\n", ret);
73 		return ret;
74 	}
75 
76 	wdt_dev->timeout = timeout;
77 
78 	return 0;
79 }
80 
da9055_wdt_ping(struct watchdog_device * wdt_dev)81 static int da9055_wdt_ping(struct watchdog_device *wdt_dev)
82 {
83 	struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
84 	struct da9055 *da9055 = driver_data->da9055;
85 
86 	/*
87 	 * We have a minimum time for watchdog window called TWDMIN. A write
88 	 * to the watchdog before this elapsed time will cause an error.
89 	 */
90 	mdelay(DA9055_TWDMIN);
91 
92 	/* Reset the watchdog timer */
93 	return da9055_reg_update(da9055, DA9055_REG_CONTROL_E,
94 				 DA9055_WATCHDOG_MASK, 1);
95 }
96 
da9055_wdt_start(struct watchdog_device * wdt_dev)97 static int da9055_wdt_start(struct watchdog_device *wdt_dev)
98 {
99 	return da9055_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
100 }
101 
da9055_wdt_stop(struct watchdog_device * wdt_dev)102 static int da9055_wdt_stop(struct watchdog_device *wdt_dev)
103 {
104 	return da9055_wdt_set_timeout(wdt_dev, 0);
105 }
106 
107 static const struct watchdog_info da9055_wdt_info = {
108 	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
109 	.identity	= "DA9055 Watchdog",
110 };
111 
112 static const struct watchdog_ops da9055_wdt_ops = {
113 	.owner = THIS_MODULE,
114 	.start = da9055_wdt_start,
115 	.stop = da9055_wdt_stop,
116 	.ping = da9055_wdt_ping,
117 	.set_timeout = da9055_wdt_set_timeout,
118 };
119 
da9055_wdt_probe(struct platform_device * pdev)120 static int da9055_wdt_probe(struct platform_device *pdev)
121 {
122 	struct device *dev = &pdev->dev;
123 	struct da9055 *da9055 = dev_get_drvdata(dev->parent);
124 	struct da9055_wdt_data *driver_data;
125 	struct watchdog_device *da9055_wdt;
126 	int ret;
127 
128 	driver_data = devm_kzalloc(dev, sizeof(*driver_data), GFP_KERNEL);
129 	if (!driver_data)
130 		return -ENOMEM;
131 
132 	driver_data->da9055 = da9055;
133 
134 	da9055_wdt = &driver_data->wdt;
135 
136 	da9055_wdt->timeout = DA9055_DEF_TIMEOUT;
137 	da9055_wdt->info = &da9055_wdt_info;
138 	da9055_wdt->ops = &da9055_wdt_ops;
139 	da9055_wdt->parent = dev;
140 	watchdog_set_nowayout(da9055_wdt, nowayout);
141 	watchdog_set_drvdata(da9055_wdt, driver_data);
142 
143 	ret = da9055_wdt_stop(da9055_wdt);
144 	if (ret < 0) {
145 		dev_err(dev, "Failed to stop watchdog, %d\n", ret);
146 		return ret;
147 	}
148 
149 	ret = devm_watchdog_register_device(dev, &driver_data->wdt);
150 	if (ret != 0)
151 		dev_err(da9055->dev, "watchdog_register_device() failed: %d\n",
152 			ret);
153 
154 	return ret;
155 }
156 
157 static struct platform_driver da9055_wdt_driver = {
158 	.probe = da9055_wdt_probe,
159 	.driver = {
160 		.name	= "da9055-watchdog",
161 	},
162 };
163 
164 module_platform_driver(da9055_wdt_driver);
165 
166 MODULE_AUTHOR("David Dajun Chen <dchen@diasemi.com>");
167 MODULE_DESCRIPTION("DA9055 watchdog");
168 MODULE_LICENSE("GPL");
169 MODULE_ALIAS("platform:da9055-watchdog");
170