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Linux/drivers/watchdog/rt2880_wdt.c

  1 /*
  2  * Ralink RT288x/RT3xxx/MT76xx built-in hardware watchdog timer
  3  *
  4  * Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
  5  * Copyright (C) 2013 John Crispin <blogic@openwrt.org>
  6  *
  7  * This driver was based on: drivers/watchdog/softdog.c
  8  *
  9  * This program is free software; you can redistribute it and/or modify it
 10  * under the terms of the GNU General Public License version 2 as published
 11  * by the Free Software Foundation.
 12  */
 13 
 14 #include <linux/clk.h>
 15 #include <linux/reset.h>
 16 #include <linux/module.h>
 17 #include <linux/kernel.h>
 18 #include <linux/watchdog.h>
 19 #include <linux/moduleparam.h>
 20 #include <linux/platform_device.h>
 21 
 22 #include <asm/mach-ralink/ralink_regs.h>
 23 
 24 #define SYSC_RSTSTAT                    0x38
 25 #define WDT_RST_CAUSE                   BIT(1)
 26 
 27 #define RALINK_WDT_TIMEOUT              30
 28 #define RALINK_WDT_PRESCALE             65536
 29 
 30 #define TIMER_REG_TMR1LOAD              0x00
 31 #define TIMER_REG_TMR1CTL               0x08
 32 
 33 #define TMRSTAT_TMR1RST                 BIT(5)
 34 
 35 #define TMR1CTL_ENABLE                  BIT(7)
 36 #define TMR1CTL_MODE_SHIFT              4
 37 #define TMR1CTL_MODE_MASK               0x3
 38 #define TMR1CTL_MODE_FREE_RUNNING       0x0
 39 #define TMR1CTL_MODE_PERIODIC           0x1
 40 #define TMR1CTL_MODE_TIMEOUT            0x2
 41 #define TMR1CTL_MODE_WDT                0x3
 42 #define TMR1CTL_PRESCALE_MASK           0xf
 43 #define TMR1CTL_PRESCALE_65536          0xf
 44 
 45 static struct clk *rt288x_wdt_clk;
 46 static unsigned long rt288x_wdt_freq;
 47 static void __iomem *rt288x_wdt_base;
 48 static struct reset_control *rt288x_wdt_reset;
 49 
 50 static bool nowayout = WATCHDOG_NOWAYOUT;
 51 module_param(nowayout, bool, 0);
 52 MODULE_PARM_DESC(nowayout,
 53                 "Watchdog cannot be stopped once started (default="
 54                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 55 
 56 static inline void rt_wdt_w32(unsigned reg, u32 val)
 57 {
 58         iowrite32(val, rt288x_wdt_base + reg);
 59 }
 60 
 61 static inline u32 rt_wdt_r32(unsigned reg)
 62 {
 63         return ioread32(rt288x_wdt_base + reg);
 64 }
 65 
 66 static int rt288x_wdt_ping(struct watchdog_device *w)
 67 {
 68         rt_wdt_w32(TIMER_REG_TMR1LOAD, w->timeout * rt288x_wdt_freq);
 69 
 70         return 0;
 71 }
 72 
 73 static int rt288x_wdt_start(struct watchdog_device *w)
 74 {
 75         u32 t;
 76 
 77         t = rt_wdt_r32(TIMER_REG_TMR1CTL);
 78         t &= ~(TMR1CTL_MODE_MASK << TMR1CTL_MODE_SHIFT |
 79                 TMR1CTL_PRESCALE_MASK);
 80         t |= (TMR1CTL_MODE_WDT << TMR1CTL_MODE_SHIFT |
 81                 TMR1CTL_PRESCALE_65536);
 82         rt_wdt_w32(TIMER_REG_TMR1CTL, t);
 83 
 84         rt288x_wdt_ping(w);
 85 
 86         t = rt_wdt_r32(TIMER_REG_TMR1CTL);
 87         t |= TMR1CTL_ENABLE;
 88         rt_wdt_w32(TIMER_REG_TMR1CTL, t);
 89 
 90         return 0;
 91 }
 92 
 93 static int rt288x_wdt_stop(struct watchdog_device *w)
 94 {
 95         u32 t;
 96 
 97         rt288x_wdt_ping(w);
 98 
 99         t = rt_wdt_r32(TIMER_REG_TMR1CTL);
100         t &= ~TMR1CTL_ENABLE;
101         rt_wdt_w32(TIMER_REG_TMR1CTL, t);
102 
103         return 0;
104 }
105 
106 static int rt288x_wdt_set_timeout(struct watchdog_device *w, unsigned int t)
107 {
108         w->timeout = t;
109         rt288x_wdt_ping(w);
110 
111         return 0;
112 }
113 
114 static int rt288x_wdt_bootcause(void)
115 {
116         if (rt_sysc_r32(SYSC_RSTSTAT) & WDT_RST_CAUSE)
117                 return WDIOF_CARDRESET;
118 
119         return 0;
120 }
121 
122 static struct watchdog_info rt288x_wdt_info = {
123         .identity = "Ralink Watchdog",
124         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
125 };
126 
127 static struct watchdog_ops rt288x_wdt_ops = {
128         .owner = THIS_MODULE,
129         .start = rt288x_wdt_start,
130         .stop = rt288x_wdt_stop,
131         .ping = rt288x_wdt_ping,
132         .set_timeout = rt288x_wdt_set_timeout,
133 };
134 
135 static struct watchdog_device rt288x_wdt_dev = {
136         .info = &rt288x_wdt_info,
137         .ops = &rt288x_wdt_ops,
138         .min_timeout = 1,
139 };
140 
141 static int rt288x_wdt_probe(struct platform_device *pdev)
142 {
143         struct resource *res;
144         int ret;
145 
146         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
147         rt288x_wdt_base = devm_ioremap_resource(&pdev->dev, res);
148         if (IS_ERR(rt288x_wdt_base))
149                 return PTR_ERR(rt288x_wdt_base);
150 
151         rt288x_wdt_clk = devm_clk_get(&pdev->dev, NULL);
152         if (IS_ERR(rt288x_wdt_clk))
153                 return PTR_ERR(rt288x_wdt_clk);
154 
155         rt288x_wdt_reset = devm_reset_control_get(&pdev->dev, NULL);
156         if (!IS_ERR(rt288x_wdt_reset))
157                 reset_control_deassert(rt288x_wdt_reset);
158 
159         rt288x_wdt_freq = clk_get_rate(rt288x_wdt_clk) / RALINK_WDT_PRESCALE;
160 
161         rt288x_wdt_dev.dev = &pdev->dev;
162         rt288x_wdt_dev.bootstatus = rt288x_wdt_bootcause();
163         rt288x_wdt_dev.max_timeout = (0xfffful / rt288x_wdt_freq);
164 
165         watchdog_init_timeout(&rt288x_wdt_dev, rt288x_wdt_dev.max_timeout,
166                               &pdev->dev);
167         watchdog_set_nowayout(&rt288x_wdt_dev, nowayout);
168 
169         ret = watchdog_register_device(&rt288x_wdt_dev);
170         if (!ret)
171                 dev_info(&pdev->dev, "Initialized\n");
172 
173         return 0;
174 }
175 
176 static int rt288x_wdt_remove(struct platform_device *pdev)
177 {
178         watchdog_unregister_device(&rt288x_wdt_dev);
179 
180         return 0;
181 }
182 
183 static void rt288x_wdt_shutdown(struct platform_device *pdev)
184 {
185         rt288x_wdt_stop(&rt288x_wdt_dev);
186 }
187 
188 static const struct of_device_id rt288x_wdt_match[] = {
189         { .compatible = "ralink,rt2880-wdt" },
190         {},
191 };
192 MODULE_DEVICE_TABLE(of, rt288x_wdt_match);
193 
194 static struct platform_driver rt288x_wdt_driver = {
195         .probe          = rt288x_wdt_probe,
196         .remove         = rt288x_wdt_remove,
197         .shutdown       = rt288x_wdt_shutdown,
198         .driver         = {
199                 .name           = KBUILD_MODNAME,
200                 .of_match_table = rt288x_wdt_match,
201         },
202 };
203 
204 module_platform_driver(rt288x_wdt_driver);
205 
206 MODULE_DESCRIPTION("MediaTek/Ralink RT288x/RT3xxx hardware watchdog driver");
207 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org");
208 MODULE_LICENSE("GPL v2");
209 

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