xref: /openbmc/linux/drivers/watchdog/meson_wdt.c (revision 4fc4dca8)
1 /*
2  *      Meson Watchdog Driver
3  *
4  *      Copyright (c) 2014 Carlo Caione
5  *
6  *      This program is free software; you can redistribute it and/or
7  *      modify it under the terms of the GNU General Public License
8  *      as published by the Free Software Foundation; either version
9  *      2 of the License, or (at your option) any later version.
10  */
11 
12 #include <linux/clk.h>
13 #include <linux/delay.h>
14 #include <linux/err.h>
15 #include <linux/init.h>
16 #include <linux/io.h>
17 #include <linux/kernel.h>
18 #include <linux/module.h>
19 #include <linux/moduleparam.h>
20 #include <linux/of.h>
21 #include <linux/of_device.h>
22 #include <linux/platform_device.h>
23 #include <linux/types.h>
24 #include <linux/watchdog.h>
25 
26 #define DRV_NAME		"meson_wdt"
27 
28 #define MESON_WDT_TC		0x00
29 #define MESON_WDT_DC_RESET	(3 << 24)
30 
31 #define MESON_WDT_RESET		0x04
32 
33 #define MESON_WDT_TIMEOUT	30
34 #define MESON_WDT_MIN_TIMEOUT	1
35 
36 #define MESON_SEC_TO_TC(s, c)	((s) * (c))
37 
38 static bool nowayout = WATCHDOG_NOWAYOUT;
39 static unsigned int timeout;
40 
41 struct meson_wdt_data {
42 	unsigned int enable;
43 	unsigned int terminal_count_mask;
44 	unsigned int count_unit;
45 };
46 
47 static struct meson_wdt_data meson6_wdt_data = {
48 	.enable			= BIT(22),
49 	.terminal_count_mask	= 0x3fffff,
50 	.count_unit		= 100000, /* 10 us */
51 };
52 
53 static struct meson_wdt_data meson8b_wdt_data = {
54 	.enable			= BIT(19),
55 	.terminal_count_mask	= 0xffff,
56 	.count_unit		= 7812, /* 128 us */
57 };
58 
59 struct meson_wdt_dev {
60 	struct watchdog_device wdt_dev;
61 	void __iomem *wdt_base;
62 	const struct meson_wdt_data *data;
63 };
64 
65 static int meson_wdt_restart(struct watchdog_device *wdt_dev,
66 			     unsigned long action, void *data)
67 {
68 	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
69 	u32 tc_reboot = MESON_WDT_DC_RESET;
70 
71 	tc_reboot |= meson_wdt->data->enable;
72 
73 	while (1) {
74 		writel(tc_reboot, meson_wdt->wdt_base + MESON_WDT_TC);
75 		mdelay(5);
76 	}
77 
78 	return 0;
79 }
80 
81 static int meson_wdt_ping(struct watchdog_device *wdt_dev)
82 {
83 	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
84 
85 	writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
86 
87 	return 0;
88 }
89 
90 static void meson_wdt_change_timeout(struct watchdog_device *wdt_dev,
91 				     unsigned int timeout)
92 {
93 	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
94 	u32 reg;
95 
96 	reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
97 	reg &= ~meson_wdt->data->terminal_count_mask;
98 	reg |= MESON_SEC_TO_TC(timeout, meson_wdt->data->count_unit);
99 	writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
100 }
101 
102 static int meson_wdt_set_timeout(struct watchdog_device *wdt_dev,
103 				 unsigned int timeout)
104 {
105 	wdt_dev->timeout = timeout;
106 
107 	meson_wdt_change_timeout(wdt_dev, timeout);
108 	meson_wdt_ping(wdt_dev);
109 
110 	return 0;
111 }
112 
113 static int meson_wdt_stop(struct watchdog_device *wdt_dev)
114 {
115 	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
116 	u32 reg;
117 
118 	reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
119 	reg &= ~meson_wdt->data->enable;
120 	writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
121 
122 	return 0;
123 }
124 
125 static int meson_wdt_start(struct watchdog_device *wdt_dev)
126 {
127 	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
128 	u32 reg;
129 
130 	meson_wdt_change_timeout(wdt_dev, meson_wdt->wdt_dev.timeout);
131 	meson_wdt_ping(wdt_dev);
132 
133 	reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
134 	reg |= meson_wdt->data->enable;
135 	writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
136 
137 	return 0;
138 }
139 
140 static const struct watchdog_info meson_wdt_info = {
141 	.identity	= DRV_NAME,
142 	.options	= WDIOF_SETTIMEOUT |
143 			  WDIOF_KEEPALIVEPING |
144 			  WDIOF_MAGICCLOSE,
145 };
146 
147 static const struct watchdog_ops meson_wdt_ops = {
148 	.owner		= THIS_MODULE,
149 	.start		= meson_wdt_start,
150 	.stop		= meson_wdt_stop,
151 	.ping		= meson_wdt_ping,
152 	.set_timeout	= meson_wdt_set_timeout,
153 	.restart        = meson_wdt_restart,
154 };
155 
156 static const struct of_device_id meson_wdt_dt_ids[] = {
157 	{ .compatible = "amlogic,meson6-wdt", .data = &meson6_wdt_data },
158 	{ .compatible = "amlogic,meson8-wdt", .data = &meson6_wdt_data },
159 	{ .compatible = "amlogic,meson8b-wdt", .data = &meson8b_wdt_data },
160 	{ .compatible = "amlogic,meson8m2-wdt", .data = &meson8b_wdt_data },
161 	{ /* sentinel */ }
162 };
163 MODULE_DEVICE_TABLE(of, meson_wdt_dt_ids);
164 
165 static int meson_wdt_probe(struct platform_device *pdev)
166 {
167 	struct device *dev = &pdev->dev;
168 	struct meson_wdt_dev *meson_wdt;
169 	const struct of_device_id *of_id;
170 	int err;
171 
172 	meson_wdt = devm_kzalloc(dev, sizeof(*meson_wdt), GFP_KERNEL);
173 	if (!meson_wdt)
174 		return -ENOMEM;
175 
176 	meson_wdt->wdt_base = devm_platform_ioremap_resource(pdev, 0);
177 	if (IS_ERR(meson_wdt->wdt_base))
178 		return PTR_ERR(meson_wdt->wdt_base);
179 
180 	of_id = of_match_device(meson_wdt_dt_ids, dev);
181 	if (!of_id) {
182 		dev_err(dev, "Unable to initialize WDT data\n");
183 		return -ENODEV;
184 	}
185 	meson_wdt->data = of_id->data;
186 
187 	meson_wdt->wdt_dev.parent = dev;
188 	meson_wdt->wdt_dev.info = &meson_wdt_info;
189 	meson_wdt->wdt_dev.ops = &meson_wdt_ops;
190 	meson_wdt->wdt_dev.max_timeout =
191 		meson_wdt->data->terminal_count_mask / meson_wdt->data->count_unit;
192 	meson_wdt->wdt_dev.min_timeout = MESON_WDT_MIN_TIMEOUT;
193 	meson_wdt->wdt_dev.timeout = min_t(unsigned int,
194 					   MESON_WDT_TIMEOUT,
195 					   meson_wdt->wdt_dev.max_timeout);
196 
197 	watchdog_set_drvdata(&meson_wdt->wdt_dev, meson_wdt);
198 
199 	watchdog_init_timeout(&meson_wdt->wdt_dev, timeout, dev);
200 	watchdog_set_nowayout(&meson_wdt->wdt_dev, nowayout);
201 	watchdog_set_restart_priority(&meson_wdt->wdt_dev, 128);
202 
203 	meson_wdt_stop(&meson_wdt->wdt_dev);
204 
205 	watchdog_stop_on_reboot(&meson_wdt->wdt_dev);
206 	err = devm_watchdog_register_device(dev, &meson_wdt->wdt_dev);
207 	if (err)
208 		return err;
209 
210 	dev_info(dev, "Watchdog enabled (timeout=%d sec, nowayout=%d)",
211 		 meson_wdt->wdt_dev.timeout, nowayout);
212 
213 	return 0;
214 }
215 
216 static struct platform_driver meson_wdt_driver = {
217 	.probe		= meson_wdt_probe,
218 	.driver		= {
219 		.name		= DRV_NAME,
220 		.of_match_table	= meson_wdt_dt_ids,
221 	},
222 };
223 
224 module_platform_driver(meson_wdt_driver);
225 
226 module_param(timeout, uint, 0);
227 MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");
228 
229 module_param(nowayout, bool, 0);
230 MODULE_PARM_DESC(nowayout,
231 		 "Watchdog cannot be stopped once started (default="
232 		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
233 
234 MODULE_LICENSE("GPL");
235 MODULE_AUTHOR("Carlo Caione <carlo@caione.org>");
236 MODULE_DESCRIPTION("Meson Watchdog Timer Driver");
237