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Linux/drivers/watchdog/bcm2835_wdt.c

  1 /*
  2  * Watchdog driver for Broadcom BCM2835
  3  *
  4  * "bcm2708_wdog" driver written by Luke Diamand that was obtained from
  5  * branch "rpi-3.6.y" of git://github.com/raspberrypi/linux.git was used
  6  * as a hardware reference for the Broadcom BCM2835 watchdog timer.
  7  *
  8  * Copyright (C) 2013 Lubomir Rintel <lkundrak@v3.sk>
  9  *
 10  * This program is free software; you can redistribute it and/or modify it
 11  * under the terms of the GNU General Public License as published by the
 12  * Free Software Foundation; either version 2 of the License, or (at your
 13  * option) any later version.
 14  */
 15 
 16 #include <linux/types.h>
 17 #include <linux/module.h>
 18 #include <linux/io.h>
 19 #include <linux/watchdog.h>
 20 #include <linux/platform_device.h>
 21 #include <linux/of_address.h>
 22 
 23 #define PM_RSTC                         0x1c
 24 #define PM_WDOG                         0x24
 25 
 26 #define PM_PASSWORD                     0x5a000000
 27 
 28 #define PM_WDOG_TIME_SET                0x000fffff
 29 #define PM_RSTC_WRCFG_CLR               0xffffffcf
 30 #define PM_RSTC_WRCFG_SET               0x00000030
 31 #define PM_RSTC_WRCFG_FULL_RESET        0x00000020
 32 #define PM_RSTC_RESET                   0x00000102
 33 
 34 #define SECS_TO_WDOG_TICKS(x) ((x) << 16)
 35 #define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
 36 
 37 struct bcm2835_wdt {
 38         void __iomem            *base;
 39         spinlock_t              lock;
 40 };
 41 
 42 static unsigned int heartbeat;
 43 static bool nowayout = WATCHDOG_NOWAYOUT;
 44 
 45 static int bcm2835_wdt_start(struct watchdog_device *wdog)
 46 {
 47         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
 48         uint32_t cur;
 49         unsigned long flags;
 50 
 51         spin_lock_irqsave(&wdt->lock, flags);
 52 
 53         writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
 54                                 PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
 55         cur = readl_relaxed(wdt->base + PM_RSTC);
 56         writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
 57                   PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
 58 
 59         spin_unlock_irqrestore(&wdt->lock, flags);
 60 
 61         return 0;
 62 }
 63 
 64 static int bcm2835_wdt_stop(struct watchdog_device *wdog)
 65 {
 66         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
 67 
 68         writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
 69         dev_info(wdog->dev, "Watchdog timer stopped");
 70         return 0;
 71 }
 72 
 73 static int bcm2835_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t)
 74 {
 75         wdog->timeout = t;
 76         return 0;
 77 }
 78 
 79 static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
 80 {
 81         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
 82 
 83         uint32_t ret = readl_relaxed(wdt->base + PM_WDOG);
 84         return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
 85 }
 86 
 87 static struct watchdog_ops bcm2835_wdt_ops = {
 88         .owner =        THIS_MODULE,
 89         .start =        bcm2835_wdt_start,
 90         .stop =         bcm2835_wdt_stop,
 91         .set_timeout =  bcm2835_wdt_set_timeout,
 92         .get_timeleft = bcm2835_wdt_get_timeleft,
 93 };
 94 
 95 static struct watchdog_info bcm2835_wdt_info = {
 96         .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
 97                         WDIOF_KEEPALIVEPING,
 98         .identity =     "Broadcom BCM2835 Watchdog timer",
 99 };
100 
101 static struct watchdog_device bcm2835_wdt_wdd = {
102         .info =         &bcm2835_wdt_info,
103         .ops =          &bcm2835_wdt_ops,
104         .min_timeout =  1,
105         .max_timeout =  WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
106         .timeout =      WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
107 };
108 
109 static int bcm2835_wdt_probe(struct platform_device *pdev)
110 {
111         struct device *dev = &pdev->dev;
112         struct device_node *np = dev->of_node;
113         struct bcm2835_wdt *wdt;
114         int err;
115 
116         wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
117         if (!wdt) {
118                 dev_err(dev, "Failed to allocate memory for watchdog device");
119                 return -ENOMEM;
120         }
121         platform_set_drvdata(pdev, wdt);
122 
123         spin_lock_init(&wdt->lock);
124 
125         wdt->base = of_iomap(np, 0);
126         if (!wdt->base) {
127                 dev_err(dev, "Failed to remap watchdog regs");
128                 return -ENODEV;
129         }
130 
131         watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
132         watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
133         watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
134         err = watchdog_register_device(&bcm2835_wdt_wdd);
135         if (err) {
136                 dev_err(dev, "Failed to register watchdog device");
137                 iounmap(wdt->base);
138                 return err;
139         }
140 
141         dev_info(dev, "Broadcom BCM2835 watchdog timer");
142         return 0;
143 }
144 
145 static int bcm2835_wdt_remove(struct platform_device *pdev)
146 {
147         struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
148 
149         watchdog_unregister_device(&bcm2835_wdt_wdd);
150         iounmap(wdt->base);
151 
152         return 0;
153 }
154 
155 static void bcm2835_wdt_shutdown(struct platform_device *pdev)
156 {
157         bcm2835_wdt_stop(&bcm2835_wdt_wdd);
158 }
159 
160 static const struct of_device_id bcm2835_wdt_of_match[] = {
161         { .compatible = "brcm,bcm2835-pm-wdt", },
162         {},
163 };
164 MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
165 
166 static struct platform_driver bcm2835_wdt_driver = {
167         .probe          = bcm2835_wdt_probe,
168         .remove         = bcm2835_wdt_remove,
169         .shutdown       = bcm2835_wdt_shutdown,
170         .driver = {
171                 .name =         "bcm2835-wdt",
172                 .owner =        THIS_MODULE,
173                 .of_match_table = bcm2835_wdt_of_match,
174         },
175 };
176 module_platform_driver(bcm2835_wdt_driver);
177 
178 module_param(heartbeat, uint, 0);
179 MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
180 
181 module_param(nowayout, bool, 0);
182 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
183                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
184 
185 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
186 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
187 MODULE_LICENSE("GPL");
188 

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