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/notifier.h>
21 #include <linux/of.h>
22 #include <linux/platform_device.h>
23 #include <linux/reboot.h>
24 #include <linux/types.h>
25 #include <linux/watchdog.h>
26
27 #define DRV_NAME "meson_wdt"
28
29 #define MESON_WDT_TC 0x00
30 #define MESON_WDT_TC_EN BIT(22)
31 #define MESON_WDT_TC_TM_MASK 0x3fffff
32 #define MESON_WDT_DC_RESET (3 << 24)
33
34 #define MESON_WDT_RESET 0x04
35
36 #define MESON_WDT_TIMEOUT 30
37 #define MESON_WDT_MIN_TIMEOUT 1
38 #define MESON_WDT_MAX_TIMEOUT (MESON_WDT_TC_TM_MASK / 100000)
39
40 #define MESON_SEC_TO_TC(s) ((s) * 100000)
41
42 static bool nowayout = WATCHDOG_NOWAYOUT;
43 static unsigned int timeout = MESON_WDT_TIMEOUT;
44
45 struct meson_wdt_dev {
46 struct watchdog_device wdt_dev;
47 void __iomem *wdt_base;
48 struct notifier_block restart_handler;
49 };
50
meson_restart_handle(struct notifier_block * this,unsigned long mode,void * cmd)51 static int meson_restart_handle(struct notifier_block *this, unsigned long mode,
52 void *cmd)
53 {
54 u32 tc_reboot = MESON_WDT_DC_RESET | MESON_WDT_TC_EN;
55 struct meson_wdt_dev *meson_wdt = container_of(this,
56 struct meson_wdt_dev,
57 restart_handler);
58
59 while (1) {
60 writel(tc_reboot, meson_wdt->wdt_base + MESON_WDT_TC);
61 mdelay(5);
62 }
63
64 return NOTIFY_DONE;
65 }
66
meson_wdt_ping(struct watchdog_device * wdt_dev)67 static int meson_wdt_ping(struct watchdog_device *wdt_dev)
68 {
69 struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
70
71 writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
72
73 return 0;
74 }
75
meson_wdt_change_timeout(struct watchdog_device * wdt_dev,unsigned int timeout)76 static void meson_wdt_change_timeout(struct watchdog_device *wdt_dev,
77 unsigned int timeout)
78 {
79 struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
80 u32 reg;
81
82 reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
83 reg &= ~MESON_WDT_TC_TM_MASK;
84 reg |= MESON_SEC_TO_TC(timeout);
85 writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
86 }
87
meson_wdt_set_timeout(struct watchdog_device * wdt_dev,unsigned int timeout)88 static int meson_wdt_set_timeout(struct watchdog_device *wdt_dev,
89 unsigned int timeout)
90 {
91 wdt_dev->timeout = timeout;
92
93 meson_wdt_change_timeout(wdt_dev, timeout);
94 meson_wdt_ping(wdt_dev);
95
96 return 0;
97 }
98
meson_wdt_stop(struct watchdog_device * wdt_dev)99 static int meson_wdt_stop(struct watchdog_device *wdt_dev)
100 {
101 struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
102 u32 reg;
103
104 reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
105 reg &= ~MESON_WDT_TC_EN;
106 writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
107
108 return 0;
109 }
110
meson_wdt_start(struct watchdog_device * wdt_dev)111 static int meson_wdt_start(struct watchdog_device *wdt_dev)
112 {
113 struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
114 u32 reg;
115
116 meson_wdt_change_timeout(wdt_dev, meson_wdt->wdt_dev.timeout);
117 meson_wdt_ping(wdt_dev);
118
119 reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
120 reg |= MESON_WDT_TC_EN;
121 writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
122
123 return 0;
124 }
125
126 static const struct watchdog_info meson_wdt_info = {
127 .identity = DRV_NAME,
128 .options = WDIOF_SETTIMEOUT |
129 WDIOF_KEEPALIVEPING |
130 WDIOF_MAGICCLOSE,
131 };
132
133 static const struct watchdog_ops meson_wdt_ops = {
134 .owner = THIS_MODULE,
135 .start = meson_wdt_start,
136 .stop = meson_wdt_stop,
137 .ping = meson_wdt_ping,
138 .set_timeout = meson_wdt_set_timeout,
139 };
140
meson_wdt_probe(struct platform_device * pdev)141 static int meson_wdt_probe(struct platform_device *pdev)
142 {
143 struct resource *res;
144 struct meson_wdt_dev *meson_wdt;
145 int err;
146
147 meson_wdt = devm_kzalloc(&pdev->dev, sizeof(*meson_wdt), GFP_KERNEL);
148 if (!meson_wdt)
149 return -ENOMEM;
150
151 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
152 meson_wdt->wdt_base = devm_ioremap_resource(&pdev->dev, res);
153 if (IS_ERR(meson_wdt->wdt_base))
154 return PTR_ERR(meson_wdt->wdt_base);
155
156 meson_wdt->wdt_dev.parent = &pdev->dev;
157 meson_wdt->wdt_dev.info = &meson_wdt_info;
158 meson_wdt->wdt_dev.ops = &meson_wdt_ops;
159 meson_wdt->wdt_dev.timeout = MESON_WDT_TIMEOUT;
160 meson_wdt->wdt_dev.max_timeout = MESON_WDT_MAX_TIMEOUT;
161 meson_wdt->wdt_dev.min_timeout = MESON_WDT_MIN_TIMEOUT;
162
163 watchdog_set_drvdata(&meson_wdt->wdt_dev, meson_wdt);
164
165 watchdog_init_timeout(&meson_wdt->wdt_dev, timeout, &pdev->dev);
166 watchdog_set_nowayout(&meson_wdt->wdt_dev, nowayout);
167
168 meson_wdt_stop(&meson_wdt->wdt_dev);
169
170 err = watchdog_register_device(&meson_wdt->wdt_dev);
171 if (err)
172 return err;
173
174 platform_set_drvdata(pdev, meson_wdt);
175
176 meson_wdt->restart_handler.notifier_call = meson_restart_handle;
177 meson_wdt->restart_handler.priority = 128;
178 err = register_restart_handler(&meson_wdt->restart_handler);
179 if (err)
180 dev_err(&pdev->dev,
181 "cannot register restart handler (err=%d)\n", err);
182
183 dev_info(&pdev->dev, "Watchdog enabled (timeout=%d sec, nowayout=%d)",
184 meson_wdt->wdt_dev.timeout, nowayout);
185
186 return 0;
187 }
188
meson_wdt_remove(struct platform_device * pdev)189 static int meson_wdt_remove(struct platform_device *pdev)
190 {
191 struct meson_wdt_dev *meson_wdt = platform_get_drvdata(pdev);
192
193 unregister_restart_handler(&meson_wdt->restart_handler);
194
195 watchdog_unregister_device(&meson_wdt->wdt_dev);
196
197 return 0;
198 }
199
meson_wdt_shutdown(struct platform_device * pdev)200 static void meson_wdt_shutdown(struct platform_device *pdev)
201 {
202 struct meson_wdt_dev *meson_wdt = platform_get_drvdata(pdev);
203
204 meson_wdt_stop(&meson_wdt->wdt_dev);
205 }
206
207 static const struct of_device_id meson_wdt_dt_ids[] = {
208 { .compatible = "amlogic,meson6-wdt" },
209 { /* sentinel */ }
210 };
211 MODULE_DEVICE_TABLE(of, meson_wdt_dt_ids);
212
213 static struct platform_driver meson_wdt_driver = {
214 .probe = meson_wdt_probe,
215 .remove = meson_wdt_remove,
216 .shutdown = meson_wdt_shutdown,
217 .driver = {
218 .owner = THIS_MODULE,
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