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Linux/drivers/watchdog/moxart_wdt.c

  1 /*
  2  * MOXA ART SoCs watchdog driver.
  3  *
  4  * Copyright (C) 2013 Jonas Jensen
  5  *
  6  * Jonas Jensen <jonas.jensen@gmail.com>
  7  *
  8  * This file is licensed under the terms of the GNU General Public
  9  * License version 2.  This program is licensed "as is" without any
 10  * warranty of any kind, whether express or implied.
 11  */
 12 
 13 #include <linux/clk.h>
 14 #include <linux/io.h>
 15 #include <linux/module.h>
 16 #include <linux/err.h>
 17 #include <linux/kernel.h>
 18 #include <linux/platform_device.h>
 19 #include <linux/watchdog.h>
 20 #include <linux/moduleparam.h>
 21 
 22 #include <asm/system_misc.h>
 23 
 24 #define REG_COUNT                       0x4
 25 #define REG_MODE                        0x8
 26 #define REG_ENABLE                      0xC
 27 
 28 struct moxart_wdt_dev {
 29         struct watchdog_device dev;
 30         void __iomem *base;
 31         unsigned int clock_frequency;
 32 };
 33 
 34 static struct moxart_wdt_dev *moxart_restart_ctx;
 35 
 36 static int heartbeat;
 37 
 38 static void moxart_wdt_restart(enum reboot_mode reboot_mode, const char *cmd)
 39 {
 40         writel(1, moxart_restart_ctx->base + REG_COUNT);
 41         writel(0x5ab9, moxart_restart_ctx->base + REG_MODE);
 42         writel(0x03, moxart_restart_ctx->base + REG_ENABLE);
 43 }
 44 
 45 static int moxart_wdt_stop(struct watchdog_device *wdt_dev)
 46 {
 47         struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
 48 
 49         writel(0, moxart_wdt->base + REG_ENABLE);
 50 
 51         return 0;
 52 }
 53 
 54 static int moxart_wdt_start(struct watchdog_device *wdt_dev)
 55 {
 56         struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
 57 
 58         writel(moxart_wdt->clock_frequency * wdt_dev->timeout,
 59                moxart_wdt->base + REG_COUNT);
 60         writel(0x5ab9, moxart_wdt->base + REG_MODE);
 61         writel(0x03, moxart_wdt->base + REG_ENABLE);
 62 
 63         return 0;
 64 }
 65 
 66 static int moxart_wdt_set_timeout(struct watchdog_device *wdt_dev,
 67                                   unsigned int timeout)
 68 {
 69         wdt_dev->timeout = timeout;
 70 
 71         return 0;
 72 }
 73 
 74 static const struct watchdog_info moxart_wdt_info = {
 75         .identity       = "moxart-wdt",
 76         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 77                           WDIOF_MAGICCLOSE,
 78 };
 79 
 80 static const struct watchdog_ops moxart_wdt_ops = {
 81         .owner          = THIS_MODULE,
 82         .start          = moxart_wdt_start,
 83         .stop           = moxart_wdt_stop,
 84         .set_timeout    = moxart_wdt_set_timeout,
 85 };
 86 
 87 static int moxart_wdt_probe(struct platform_device *pdev)
 88 {
 89         struct moxart_wdt_dev *moxart_wdt;
 90         struct device *dev = &pdev->dev;
 91         struct device_node *node = dev->of_node;
 92         struct resource *res;
 93         struct clk *clk;
 94         int err;
 95         unsigned int max_timeout;
 96         bool nowayout = WATCHDOG_NOWAYOUT;
 97 
 98         moxart_wdt = devm_kzalloc(dev, sizeof(*moxart_wdt), GFP_KERNEL);
 99         if (!moxart_wdt)
100                 return -ENOMEM;
101 
102         platform_set_drvdata(pdev, moxart_wdt);
103 
104         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
105         moxart_wdt->base = devm_ioremap_resource(dev, res);
106         if (IS_ERR(moxart_wdt->base))
107                 return PTR_ERR(moxart_wdt->base);
108 
109         clk = of_clk_get(node, 0);
110         if (IS_ERR(clk)) {
111                 pr_err("%s: of_clk_get failed\n", __func__);
112                 return PTR_ERR(clk);
113         }
114 
115         moxart_wdt->clock_frequency = clk_get_rate(clk);
116         if (moxart_wdt->clock_frequency == 0) {
117                 pr_err("%s: incorrect clock frequency\n", __func__);
118                 return -EINVAL;
119         }
120 
121         max_timeout = UINT_MAX / moxart_wdt->clock_frequency;
122 
123         moxart_wdt->dev.info = &moxart_wdt_info;
124         moxart_wdt->dev.ops = &moxart_wdt_ops;
125         moxart_wdt->dev.timeout = max_timeout;
126         moxart_wdt->dev.min_timeout = 1;
127         moxart_wdt->dev.max_timeout = max_timeout;
128         moxart_wdt->dev.parent = dev;
129 
130         watchdog_init_timeout(&moxart_wdt->dev, heartbeat, dev);
131         watchdog_set_nowayout(&moxart_wdt->dev, nowayout);
132 
133         watchdog_set_drvdata(&moxart_wdt->dev, moxart_wdt);
134 
135         err = watchdog_register_device(&moxart_wdt->dev);
136         if (err)
137                 return err;
138 
139         moxart_restart_ctx = moxart_wdt;
140         arm_pm_restart = moxart_wdt_restart;
141 
142         dev_dbg(dev, "Watchdog enabled (heartbeat=%d sec, nowayout=%d)\n",
143                 moxart_wdt->dev.timeout, nowayout);
144 
145         return 0;
146 }
147 
148 static int moxart_wdt_remove(struct platform_device *pdev)
149 {
150         struct moxart_wdt_dev *moxart_wdt = platform_get_drvdata(pdev);
151 
152         arm_pm_restart = NULL;
153         moxart_wdt_stop(&moxart_wdt->dev);
154         watchdog_unregister_device(&moxart_wdt->dev);
155 
156         return 0;
157 }
158 
159 static const struct of_device_id moxart_watchdog_match[] = {
160         { .compatible = "moxa,moxart-watchdog" },
161         { },
162 };
163 
164 static struct platform_driver moxart_wdt_driver = {
165         .probe      = moxart_wdt_probe,
166         .remove     = moxart_wdt_remove,
167         .driver     = {
168                 .name           = "moxart-watchdog",
169                 .owner          = THIS_MODULE,
170                 .of_match_table = moxart_watchdog_match,
171         },
172 };
173 module_platform_driver(moxart_wdt_driver);
174 
175 module_param(heartbeat, int, 0);
176 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds");
177 
178 MODULE_DESCRIPTION("MOXART watchdog driver");
179 MODULE_LICENSE("GPL");
180 MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");
181 

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