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Linux/drivers/watchdog/txx9wdt.c

  1 /*
  2  * txx9wdt: A Hardware Watchdog Driver for TXx9 SoCs
  3  *
  4  * Copyright (C) 2007 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
  5  *
  6  * This program is free software; you can redistribute it and/or modify
  7  * it under the terms of the GNU General Public License version 2 as
  8  * published by the Free Software Foundation.
  9  */
 10 
 11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 12 
 13 #include <linux/module.h>
 14 #include <linux/moduleparam.h>
 15 #include <linux/types.h>
 16 #include <linux/watchdog.h>
 17 #include <linux/init.h>
 18 #include <linux/platform_device.h>
 19 #include <linux/clk.h>
 20 #include <linux/err.h>
 21 #include <linux/io.h>
 22 #include <asm/txx9tmr.h>
 23 
 24 #define WD_TIMER_CCD    7               /* 1/256 */
 25 #define WD_TIMER_CLK    (clk_get_rate(txx9_imclk) / (2 << WD_TIMER_CCD))
 26 #define WD_MAX_TIMEOUT  ((0xffffffff >> (32 - TXX9_TIMER_BITS)) / WD_TIMER_CLK)
 27 #define TIMER_MARGIN    60              /* Default is 60 seconds */
 28 
 29 static unsigned int timeout = TIMER_MARGIN;     /* in seconds */
 30 module_param(timeout, uint, 0);
 31 MODULE_PARM_DESC(timeout,
 32         "Watchdog timeout in seconds. "
 33         "(0<timeout<((2^" __MODULE_STRING(TXX9_TIMER_BITS) ")/(IMCLK/256)), "
 34         "default=" __MODULE_STRING(TIMER_MARGIN) ")");
 35 
 36 static bool nowayout = WATCHDOG_NOWAYOUT;
 37 module_param(nowayout, bool, 0);
 38 MODULE_PARM_DESC(nowayout,
 39         "Watchdog cannot be stopped once started "
 40         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 41 
 42 static struct txx9_tmr_reg __iomem *txx9wdt_reg;
 43 static struct clk *txx9_imclk;
 44 static DEFINE_SPINLOCK(txx9_lock);
 45 
 46 static int txx9wdt_ping(struct watchdog_device *wdt_dev)
 47 {
 48         spin_lock(&txx9_lock);
 49         __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
 50         spin_unlock(&txx9_lock);
 51         return 0;
 52 }
 53 
 54 static int txx9wdt_start(struct watchdog_device *wdt_dev)
 55 {
 56         spin_lock(&txx9_lock);
 57         __raw_writel(WD_TIMER_CLK * wdt_dev->timeout, &txx9wdt_reg->cpra);
 58         __raw_writel(WD_TIMER_CCD, &txx9wdt_reg->ccdr);
 59         __raw_writel(0, &txx9wdt_reg->tisr);    /* clear pending interrupt */
 60         __raw_writel(TXx9_TMTCR_TCE | TXx9_TMTCR_CCDE | TXx9_TMTCR_TMODE_WDOG,
 61                      &txx9wdt_reg->tcr);
 62         __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
 63         spin_unlock(&txx9_lock);
 64         return 0;
 65 }
 66 
 67 static int txx9wdt_stop(struct watchdog_device *wdt_dev)
 68 {
 69         spin_lock(&txx9_lock);
 70         __raw_writel(TXx9_TMWTMR_WDIS, &txx9wdt_reg->wtmr);
 71         __raw_writel(__raw_readl(&txx9wdt_reg->tcr) & ~TXx9_TMTCR_TCE,
 72                      &txx9wdt_reg->tcr);
 73         spin_unlock(&txx9_lock);
 74         return 0;
 75 }
 76 
 77 static int txx9wdt_set_timeout(struct watchdog_device *wdt_dev,
 78                                unsigned int new_timeout)
 79 {
 80         wdt_dev->timeout = new_timeout;
 81         txx9wdt_stop(wdt_dev);
 82         txx9wdt_start(wdt_dev);
 83         return 0;
 84 }
 85 
 86 static const struct watchdog_info txx9wdt_info = {
 87         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 88         .identity = "Hardware Watchdog for TXx9",
 89 };
 90 
 91 static const struct watchdog_ops txx9wdt_ops = {
 92         .owner = THIS_MODULE,
 93         .start = txx9wdt_start,
 94         .stop = txx9wdt_stop,
 95         .ping = txx9wdt_ping,
 96         .set_timeout = txx9wdt_set_timeout,
 97 };
 98 
 99 static struct watchdog_device txx9wdt = {
100         .info = &txx9wdt_info,
101         .ops = &txx9wdt_ops,
102 };
103 
104 static int __init txx9wdt_probe(struct platform_device *dev)
105 {
106         struct resource *res;
107         int ret;
108 
109         txx9_imclk = clk_get(NULL, "imbus_clk");
110         if (IS_ERR(txx9_imclk)) {
111                 ret = PTR_ERR(txx9_imclk);
112                 txx9_imclk = NULL;
113                 goto exit;
114         }
115         ret = clk_enable(txx9_imclk);
116         if (ret) {
117                 clk_put(txx9_imclk);
118                 txx9_imclk = NULL;
119                 goto exit;
120         }
121 
122         res = platform_get_resource(dev, IORESOURCE_MEM, 0);
123         txx9wdt_reg = devm_ioremap_resource(&dev->dev, res);
124         if (IS_ERR(txx9wdt_reg)) {
125                 ret = PTR_ERR(txx9wdt_reg);
126                 goto exit;
127         }
128 
129         if (timeout < 1 || timeout > WD_MAX_TIMEOUT)
130                 timeout = TIMER_MARGIN;
131         txx9wdt.timeout = timeout;
132         txx9wdt.min_timeout = 1;
133         txx9wdt.max_timeout = WD_MAX_TIMEOUT;
134         watchdog_set_nowayout(&txx9wdt, nowayout);
135 
136         ret = watchdog_register_device(&txx9wdt);
137         if (ret)
138                 goto exit;
139 
140         pr_info("Hardware Watchdog Timer: timeout=%d sec (max %ld) (nowayout= %d)\n",
141                 timeout, WD_MAX_TIMEOUT, nowayout);
142 
143         return 0;
144 exit:
145         if (txx9_imclk) {
146                 clk_disable(txx9_imclk);
147                 clk_put(txx9_imclk);
148         }
149         return ret;
150 }
151 
152 static int __exit txx9wdt_remove(struct platform_device *dev)
153 {
154         watchdog_unregister_device(&txx9wdt);
155         clk_disable(txx9_imclk);
156         clk_put(txx9_imclk);
157         return 0;
158 }
159 
160 static void txx9wdt_shutdown(struct platform_device *dev)
161 {
162         txx9wdt_stop(&txx9wdt);
163 }
164 
165 static struct platform_driver txx9wdt_driver = {
166         .remove = __exit_p(txx9wdt_remove),
167         .shutdown = txx9wdt_shutdown,
168         .driver = {
169                 .name = "txx9wdt",
170                 .owner = THIS_MODULE,
171         },
172 };
173 
174 module_platform_driver_probe(txx9wdt_driver, txx9wdt_probe);
175 
176 MODULE_DESCRIPTION("TXx9 Watchdog Driver");
177 MODULE_LICENSE("GPL");
178 MODULE_ALIAS("platform:txx9wdt");
179 

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