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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/delay.h>
 17 #include <linux/reboot.h>
 18 #include <linux/types.h>
 19 #include <linux/module.h>
 20 #include <linux/io.h>
 21 #include <linux/watchdog.h>
 22 #include <linux/platform_device.h>
 23 #include <linux/of_address.h>
 24 #include <linux/of_platform.h>
 25 
 26 #define PM_RSTC                         0x1c
 27 #define PM_RSTS                         0x20
 28 #define PM_WDOG                         0x24
 29 
 30 #define PM_PASSWORD                     0x5a000000
 31 
 32 #define PM_WDOG_TIME_SET                0x000fffff
 33 #define PM_RSTC_WRCFG_CLR               0xffffffcf
 34 #define PM_RSTS_HADWRH_SET              0x00000040
 35 #define PM_RSTC_WRCFG_SET               0x00000030
 36 #define PM_RSTC_WRCFG_FULL_RESET        0x00000020
 37 #define PM_RSTC_RESET                   0x00000102
 38 
 39 /*
 40  * The Raspberry Pi firmware uses the RSTS register to know which partiton
 41  * to boot from. The partiton value is spread into bits 0, 2, 4, 6, 8, 10.
 42  * Partiton 63 is a special partition used by the firmware to indicate halt.
 43  */
 44 #define PM_RSTS_RASPBERRYPI_HALT        0x555
 45 
 46 #define SECS_TO_WDOG_TICKS(x) ((x) << 16)
 47 #define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
 48 
 49 struct bcm2835_wdt {
 50         void __iomem            *base;
 51         spinlock_t              lock;
 52         struct notifier_block   restart_handler;
 53 };
 54 
 55 static unsigned int heartbeat;
 56 static bool nowayout = WATCHDOG_NOWAYOUT;
 57 
 58 static bool bcm2835_wdt_is_running(struct bcm2835_wdt *wdt)
 59 {
 60         uint32_t cur;
 61 
 62         cur = readl(wdt->base + PM_RSTC);
 63 
 64         return !!(cur & PM_RSTC_WRCFG_FULL_RESET);
 65 }
 66 
 67 static int bcm2835_wdt_start(struct watchdog_device *wdog)
 68 {
 69         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
 70         uint32_t cur;
 71         unsigned long flags;
 72 
 73         spin_lock_irqsave(&wdt->lock, flags);
 74 
 75         writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
 76                                 PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
 77         cur = readl_relaxed(wdt->base + PM_RSTC);
 78         writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
 79                   PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
 80 
 81         spin_unlock_irqrestore(&wdt->lock, flags);
 82 
 83         return 0;
 84 }
 85 
 86 static int bcm2835_wdt_stop(struct watchdog_device *wdog)
 87 {
 88         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
 89 
 90         writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
 91         return 0;
 92 }
 93 
 94 static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
 95 {
 96         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
 97 
 98         uint32_t ret = readl_relaxed(wdt->base + PM_WDOG);
 99         return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
100 }
101 
102 static const struct watchdog_ops bcm2835_wdt_ops = {
103         .owner =        THIS_MODULE,
104         .start =        bcm2835_wdt_start,
105         .stop =         bcm2835_wdt_stop,
106         .get_timeleft = bcm2835_wdt_get_timeleft,
107 };
108 
109 static const struct watchdog_info bcm2835_wdt_info = {
110         .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
111                         WDIOF_KEEPALIVEPING,
112         .identity =     "Broadcom BCM2835 Watchdog timer",
113 };
114 
115 static struct watchdog_device bcm2835_wdt_wdd = {
116         .info =         &bcm2835_wdt_info,
117         .ops =          &bcm2835_wdt_ops,
118         .min_timeout =  1,
119         .max_timeout =  WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
120         .timeout =      WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
121 };
122 
123 static int
124 bcm2835_restart(struct notifier_block *this, unsigned long mode, void *cmd)
125 {
126         struct bcm2835_wdt *wdt = container_of(this, struct bcm2835_wdt,
127                                                restart_handler);
128         u32 val;
129 
130         /* use a timeout of 10 ticks (~150us) */
131         writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG);
132         val = readl_relaxed(wdt->base + PM_RSTC);
133         val &= PM_RSTC_WRCFG_CLR;
134         val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET;
135         writel_relaxed(val, wdt->base + PM_RSTC);
136 
137         /* No sleeping, possibly atomic. */
138         mdelay(1);
139 
140         return 0;
141 }
142 
143 /*
144  * We can't really power off, but if we do the normal reset scheme, and
145  * indicate to bootcode.bin not to reboot, then most of the chip will be
146  * powered off.
147  */
148 static void bcm2835_power_off(void)
149 {
150         struct device_node *np =
151                 of_find_compatible_node(NULL, NULL, "brcm,bcm2835-pm-wdt");
152         struct platform_device *pdev = of_find_device_by_node(np);
153         struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
154         u32 val;
155 
156         /*
157          * We set the watchdog hard reset bit here to distinguish this reset
158          * from the normal (full) reset. bootcode.bin will not reboot after a
159          * hard reset.
160          */
161         val = readl_relaxed(wdt->base + PM_RSTS);
162         val |= PM_PASSWORD | PM_RSTS_RASPBERRYPI_HALT;
163         writel_relaxed(val, wdt->base + PM_RSTS);
164 
165         /* Continue with normal reset mechanism */
166         bcm2835_restart(&wdt->restart_handler, REBOOT_HARD, NULL);
167 }
168 
169 static int bcm2835_wdt_probe(struct platform_device *pdev)
170 {
171         struct device *dev = &pdev->dev;
172         struct device_node *np = dev->of_node;
173         struct bcm2835_wdt *wdt;
174         int err;
175 
176         wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
177         if (!wdt)
178                 return -ENOMEM;
179         platform_set_drvdata(pdev, wdt);
180 
181         spin_lock_init(&wdt->lock);
182 
183         wdt->base = of_iomap(np, 0);
184         if (!wdt->base) {
185                 dev_err(dev, "Failed to remap watchdog regs");
186                 return -ENODEV;
187         }
188 
189         watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
190         watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
191         watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
192         bcm2835_wdt_wdd.parent = &pdev->dev;
193         if (bcm2835_wdt_is_running(wdt)) {
194                 /*
195                  * The currently active timeout value (set by the
196                  * bootloader) may be different from the module
197                  * heartbeat parameter or the value in device
198                  * tree. But we just need to set WDOG_HW_RUNNING,
199                  * because then the framework will "immediately" ping
200                  * the device, updating the timeout.
201                  */
202                 set_bit(WDOG_HW_RUNNING, &bcm2835_wdt_wdd.status);
203         }
204         err = watchdog_register_device(&bcm2835_wdt_wdd);
205         if (err) {
206                 dev_err(dev, "Failed to register watchdog device");
207                 iounmap(wdt->base);
208                 return err;
209         }
210 
211         wdt->restart_handler.notifier_call = bcm2835_restart;
212         wdt->restart_handler.priority = 128;
213         register_restart_handler(&wdt->restart_handler);
214         if (pm_power_off == NULL)
215                 pm_power_off = bcm2835_power_off;
216 
217         dev_info(dev, "Broadcom BCM2835 watchdog timer");
218         return 0;
219 }
220 
221 static int bcm2835_wdt_remove(struct platform_device *pdev)
222 {
223         struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
224 
225         unregister_restart_handler(&wdt->restart_handler);
226         if (pm_power_off == bcm2835_power_off)
227                 pm_power_off = NULL;
228         watchdog_unregister_device(&bcm2835_wdt_wdd);
229         iounmap(wdt->base);
230 
231         return 0;
232 }
233 
234 static void bcm2835_wdt_shutdown(struct platform_device *pdev)
235 {
236         bcm2835_wdt_stop(&bcm2835_wdt_wdd);
237 }
238 
239 static const struct of_device_id bcm2835_wdt_of_match[] = {
240         { .compatible = "brcm,bcm2835-pm-wdt", },
241         {},
242 };
243 MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
244 
245 static struct platform_driver bcm2835_wdt_driver = {
246         .probe          = bcm2835_wdt_probe,
247         .remove         = bcm2835_wdt_remove,
248         .shutdown       = bcm2835_wdt_shutdown,
249         .driver = {
250                 .name =         "bcm2835-wdt",
251                 .of_match_table = bcm2835_wdt_of_match,
252         },
253 };
254 module_platform_driver(bcm2835_wdt_driver);
255 
256 module_param(heartbeat, uint, 0);
257 MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
258 
259 module_param(nowayout, bool, 0);
260 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
261                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
262 
263 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
264 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
265 MODULE_LICENSE("GPL");
266 

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