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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 
 49 static bool nowayout = WATCHDOG_NOWAYOUT;
 50 module_param(nowayout, bool, 0);
 51 MODULE_PARM_DESC(nowayout,
 52                 "Watchdog cannot be stopped once started (default="
 53                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 54 
 55 static inline void rt_wdt_w32(unsigned reg, u32 val)
 56 {
 57         iowrite32(val, rt288x_wdt_base + reg);
 58 }
 59 
 60 static inline u32 rt_wdt_r32(unsigned reg)
 61 {
 62         return ioread32(rt288x_wdt_base + reg);
 63 }
 64 
 65 static int rt288x_wdt_ping(struct watchdog_device *w)
 66 {
 67         rt_wdt_w32(TIMER_REG_TMR1LOAD, w->timeout * rt288x_wdt_freq);
 68 
 69         return 0;
 70 }
 71 
 72 static int rt288x_wdt_start(struct watchdog_device *w)
 73 {
 74         u32 t;
 75 
 76         t = rt_wdt_r32(TIMER_REG_TMR1CTL);
 77         t &= ~(TMR1CTL_MODE_MASK << TMR1CTL_MODE_SHIFT |
 78                 TMR1CTL_PRESCALE_MASK);
 79         t |= (TMR1CTL_MODE_WDT << TMR1CTL_MODE_SHIFT |
 80                 TMR1CTL_PRESCALE_65536);
 81         rt_wdt_w32(TIMER_REG_TMR1CTL, t);
 82 
 83         rt288x_wdt_ping(w);
 84 
 85         t = rt_wdt_r32(TIMER_REG_TMR1CTL);
 86         t |= TMR1CTL_ENABLE;
 87         rt_wdt_w32(TIMER_REG_TMR1CTL, t);
 88 
 89         return 0;
 90 }
 91 
 92 static int rt288x_wdt_stop(struct watchdog_device *w)
 93 {
 94         u32 t;
 95 
 96         rt288x_wdt_ping(w);
 97 
 98         t = rt_wdt_r32(TIMER_REG_TMR1CTL);
 99         t &= ~TMR1CTL_ENABLE;
100         rt_wdt_w32(TIMER_REG_TMR1CTL, t);
101 
102         return 0;
103 }
104 
105 static int rt288x_wdt_set_timeout(struct watchdog_device *w, unsigned int t)
106 {
107         w->timeout = t;
108         rt288x_wdt_ping(w);
109 
110         return 0;
111 }
112 
113 static int rt288x_wdt_bootcause(void)
114 {
115         if (rt_sysc_r32(SYSC_RSTSTAT) & WDT_RST_CAUSE)
116                 return WDIOF_CARDRESET;
117 
118         return 0;
119 }
120 
121 static struct watchdog_info rt288x_wdt_info = {
122         .identity = "Ralink Watchdog",
123         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
124 };
125 
126 static struct watchdog_ops rt288x_wdt_ops = {
127         .owner = THIS_MODULE,
128         .start = rt288x_wdt_start,
129         .stop = rt288x_wdt_stop,
130         .ping = rt288x_wdt_ping,
131         .set_timeout = rt288x_wdt_set_timeout,
132 };
133 
134 static struct watchdog_device rt288x_wdt_dev = {
135         .info = &rt288x_wdt_info,
136         .ops = &rt288x_wdt_ops,
137         .min_timeout = 1,
138 };
139 
140 static int rt288x_wdt_probe(struct platform_device *pdev)
141 {
142         struct resource *res;
143         int ret;
144 
145         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
146         rt288x_wdt_base = devm_ioremap_resource(&pdev->dev, res);
147         if (IS_ERR(rt288x_wdt_base))
148                 return PTR_ERR(rt288x_wdt_base);
149 
150         rt288x_wdt_clk = devm_clk_get(&pdev->dev, NULL);
151         if (IS_ERR(rt288x_wdt_clk))
152                 return PTR_ERR(rt288x_wdt_clk);
153 
154         device_reset(&pdev->dev);
155 
156         rt288x_wdt_freq = clk_get_rate(rt288x_wdt_clk) / RALINK_WDT_PRESCALE;
157 
158         rt288x_wdt_dev.dev = &pdev->dev;
159         rt288x_wdt_dev.bootstatus = rt288x_wdt_bootcause();
160 
161         rt288x_wdt_dev.max_timeout = (0xfffful / rt288x_wdt_freq);
162         rt288x_wdt_dev.timeout = rt288x_wdt_dev.max_timeout;
163 
164         watchdog_set_nowayout(&rt288x_wdt_dev, nowayout);
165 
166         ret = watchdog_register_device(&rt288x_wdt_dev);
167         if (!ret)
168                 dev_info(&pdev->dev, "Initialized\n");
169 
170         return 0;
171 }
172 
173 static int rt288x_wdt_remove(struct platform_device *pdev)
174 {
175         watchdog_unregister_device(&rt288x_wdt_dev);
176 
177         return 0;
178 }
179 
180 static void rt288x_wdt_shutdown(struct platform_device *pdev)
181 {
182         rt288x_wdt_stop(&rt288x_wdt_dev);
183 }
184 
185 static const struct of_device_id rt288x_wdt_match[] = {
186         { .compatible = "ralink,rt2880-wdt" },
187         {},
188 };
189 MODULE_DEVICE_TABLE(of, rt288x_wdt_match);
190 
191 static struct platform_driver rt288x_wdt_driver = {
192         .probe          = rt288x_wdt_probe,
193         .remove         = rt288x_wdt_remove,
194         .shutdown       = rt288x_wdt_shutdown,
195         .driver         = {
196                 .name           = KBUILD_MODNAME,
197                 .owner          = THIS_MODULE,
198                 .of_match_table = rt288x_wdt_match,
199         },
200 };
201 
202 module_platform_driver(rt288x_wdt_driver);
203 
204 MODULE_DESCRIPTION("MediaTek/Ralink RT288x/RT3xxx hardware watchdog driver");
205 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org");
206 MODULE_LICENSE("GPL v2");
207 

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