1 | // SPDX-License-Identifier: GPL-2.0+ |
2 | /* |
3 | * Watchdog driver for Broadcom BCM2835 |
4 | * |
5 | * "bcm2708_wdog" driver written by Luke Diamand that was obtained from |
6 | * branch "rpi-3.6.y" of git://github.com/raspberrypi/linux.git was used |
7 | * as a hardware reference for the Broadcom BCM2835 watchdog timer. |
8 | * |
9 | * Copyright (C) 2013 Lubomir Rintel <lkundrak@v3.sk> |
10 | * |
11 | */ |
12 | |
13 | #include <linux/delay.h> |
14 | #include <linux/types.h> |
15 | #include <linux/mfd/bcm2835-pm.h> |
16 | #include <linux/module.h> |
17 | #include <linux/io.h> |
18 | #include <linux/watchdog.h> |
19 | #include <linux/platform_device.h> |
20 | #include <linux/of_address.h> |
21 | #include <linux/of_platform.h> |
22 | |
23 | #define PM_RSTC 0x1c |
24 | #define PM_RSTS 0x20 |
25 | #define PM_WDOG 0x24 |
26 | |
27 | #define PM_PASSWORD 0x5a000000 |
28 | |
29 | #define PM_WDOG_TIME_SET 0x000fffff |
30 | #define PM_RSTC_WRCFG_CLR 0xffffffcf |
31 | #define PM_RSTS_HADWRH_SET 0x00000040 |
32 | #define PM_RSTC_WRCFG_SET 0x00000030 |
33 | #define PM_RSTC_WRCFG_FULL_RESET 0x00000020 |
34 | #define PM_RSTC_RESET 0x00000102 |
35 | |
36 | /* |
37 | * The Raspberry Pi firmware uses the RSTS register to know which partition |
38 | * to boot from. The partition value is spread into bits 0, 2, 4, 6, 8, 10. |
39 | * Partition 63 is a special partition used by the firmware to indicate halt. |
40 | */ |
41 | #define PM_RSTS_RASPBERRYPI_HALT 0x555 |
42 | |
43 | #define SECS_TO_WDOG_TICKS(x) ((x) << 16) |
44 | #define WDOG_TICKS_TO_SECS(x) ((x) >> 16) |
45 | |
46 | struct bcm2835_wdt { |
47 | void __iomem *base; |
48 | spinlock_t lock; |
49 | }; |
50 | |
51 | static struct bcm2835_wdt *bcm2835_power_off_wdt; |
52 | |
53 | static unsigned int heartbeat; |
54 | static bool nowayout = WATCHDOG_NOWAYOUT; |
55 | |
56 | static bool bcm2835_wdt_is_running(struct bcm2835_wdt *wdt) |
57 | { |
58 | uint32_t cur; |
59 | |
60 | cur = readl(addr: wdt->base + PM_RSTC); |
61 | |
62 | return !!(cur & PM_RSTC_WRCFG_FULL_RESET); |
63 | } |
64 | |
65 | static int bcm2835_wdt_start(struct watchdog_device *wdog) |
66 | { |
67 | struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdd: wdog); |
68 | uint32_t cur; |
69 | unsigned long flags; |
70 | |
71 | spin_lock_irqsave(&wdt->lock, flags); |
72 | |
73 | writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) & |
74 | PM_WDOG_TIME_SET), wdt->base + PM_WDOG); |
75 | cur = readl_relaxed(wdt->base + PM_RSTC); |
76 | writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) | |
77 | PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC); |
78 | |
79 | spin_unlock_irqrestore(lock: &wdt->lock, flags); |
80 | |
81 | return 0; |
82 | } |
83 | |
84 | static int bcm2835_wdt_stop(struct watchdog_device *wdog) |
85 | { |
86 | struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdd: wdog); |
87 | |
88 | writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC); |
89 | return 0; |
90 | } |
91 | |
92 | static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog) |
93 | { |
94 | struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdd: wdog); |
95 | |
96 | uint32_t ret = readl_relaxed(wdt->base + PM_WDOG); |
97 | return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET); |
98 | } |
99 | |
100 | static void __bcm2835_restart(struct bcm2835_wdt *wdt) |
101 | { |
102 | u32 val; |
103 | |
104 | /* use a timeout of 10 ticks (~150us) */ |
105 | writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG); |
106 | val = readl_relaxed(wdt->base + PM_RSTC); |
107 | val &= PM_RSTC_WRCFG_CLR; |
108 | val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET; |
109 | writel_relaxed(val, wdt->base + PM_RSTC); |
110 | |
111 | /* No sleeping, possibly atomic. */ |
112 | mdelay(1); |
113 | } |
114 | |
115 | static int bcm2835_restart(struct watchdog_device *wdog, |
116 | unsigned long action, void *data) |
117 | { |
118 | struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdd: wdog); |
119 | |
120 | __bcm2835_restart(wdt); |
121 | |
122 | return 0; |
123 | } |
124 | |
125 | static const struct watchdog_ops bcm2835_wdt_ops = { |
126 | .owner = THIS_MODULE, |
127 | .start = bcm2835_wdt_start, |
128 | .stop = bcm2835_wdt_stop, |
129 | .get_timeleft = bcm2835_wdt_get_timeleft, |
130 | .restart = bcm2835_restart, |
131 | }; |
132 | |
133 | static const struct watchdog_info bcm2835_wdt_info = { |
134 | .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | |
135 | WDIOF_KEEPALIVEPING, |
136 | .identity = "Broadcom BCM2835 Watchdog timer" , |
137 | }; |
138 | |
139 | static struct watchdog_device bcm2835_wdt_wdd = { |
140 | .info = &bcm2835_wdt_info, |
141 | .ops = &bcm2835_wdt_ops, |
142 | .min_timeout = 1, |
143 | .max_timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET), |
144 | .timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET), |
145 | }; |
146 | |
147 | /* |
148 | * We can't really power off, but if we do the normal reset scheme, and |
149 | * indicate to bootcode.bin not to reboot, then most of the chip will be |
150 | * powered off. |
151 | */ |
152 | static void bcm2835_power_off(void) |
153 | { |
154 | struct bcm2835_wdt *wdt = bcm2835_power_off_wdt; |
155 | u32 val; |
156 | |
157 | /* |
158 | * We set the watchdog hard reset bit here to distinguish this reset |
159 | * from the normal (full) reset. bootcode.bin will not reboot after a |
160 | * hard reset. |
161 | */ |
162 | val = readl_relaxed(wdt->base + PM_RSTS); |
163 | val |= PM_PASSWORD | PM_RSTS_RASPBERRYPI_HALT; |
164 | writel_relaxed(val, wdt->base + PM_RSTS); |
165 | |
166 | /* Continue with normal reset mechanism */ |
167 | __bcm2835_restart(wdt); |
168 | } |
169 | |
170 | static int bcm2835_wdt_probe(struct platform_device *pdev) |
171 | { |
172 | struct bcm2835_pm *pm = dev_get_drvdata(dev: pdev->dev.parent); |
173 | struct device *dev = &pdev->dev; |
174 | struct bcm2835_wdt *wdt; |
175 | int err; |
176 | |
177 | wdt = devm_kzalloc(dev, size: sizeof(struct bcm2835_wdt), GFP_KERNEL); |
178 | if (!wdt) |
179 | return -ENOMEM; |
180 | |
181 | spin_lock_init(&wdt->lock); |
182 | |
183 | wdt->base = pm->base; |
184 | |
185 | watchdog_set_drvdata(wdd: &bcm2835_wdt_wdd, data: wdt); |
186 | watchdog_init_timeout(wdd: &bcm2835_wdt_wdd, timeout_parm: heartbeat, dev); |
187 | watchdog_set_nowayout(wdd: &bcm2835_wdt_wdd, nowayout); |
188 | bcm2835_wdt_wdd.parent = dev; |
189 | if (bcm2835_wdt_is_running(wdt)) { |
190 | /* |
191 | * The currently active timeout value (set by the |
192 | * bootloader) may be different from the module |
193 | * heartbeat parameter or the value in device |
194 | * tree. But we just need to set WDOG_HW_RUNNING, |
195 | * because then the framework will "immediately" ping |
196 | * the device, updating the timeout. |
197 | */ |
198 | set_bit(WDOG_HW_RUNNING, addr: &bcm2835_wdt_wdd.status); |
199 | } |
200 | |
201 | watchdog_set_restart_priority(wdd: &bcm2835_wdt_wdd, priority: 128); |
202 | |
203 | watchdog_stop_on_reboot(wdd: &bcm2835_wdt_wdd); |
204 | err = devm_watchdog_register_device(dev, &bcm2835_wdt_wdd); |
205 | if (err) |
206 | return err; |
207 | |
208 | if (of_device_is_system_power_controller(np: pdev->dev.parent->of_node)) { |
209 | if (!pm_power_off) { |
210 | pm_power_off = bcm2835_power_off; |
211 | bcm2835_power_off_wdt = wdt; |
212 | } else { |
213 | dev_info(dev, "Poweroff handler already present!\n" ); |
214 | } |
215 | } |
216 | |
217 | dev_info(dev, "Broadcom BCM2835 watchdog timer" ); |
218 | return 0; |
219 | } |
220 | |
221 | static void bcm2835_wdt_remove(struct platform_device *pdev) |
222 | { |
223 | if (pm_power_off == bcm2835_power_off) |
224 | pm_power_off = NULL; |
225 | } |
226 | |
227 | static struct platform_driver bcm2835_wdt_driver = { |
228 | .probe = bcm2835_wdt_probe, |
229 | .remove_new = bcm2835_wdt_remove, |
230 | .driver = { |
231 | .name = "bcm2835-wdt" , |
232 | }, |
233 | }; |
234 | module_platform_driver(bcm2835_wdt_driver); |
235 | |
236 | module_param(heartbeat, uint, 0); |
237 | MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds" ); |
238 | |
239 | module_param(nowayout, bool, 0); |
240 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" |
241 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")" ); |
242 | |
243 | MODULE_ALIAS("platform:bcm2835-wdt" ); |
244 | MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>" ); |
245 | MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer" ); |
246 | MODULE_LICENSE("GPL" ); |
247 | |