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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/notifier.h>
 19 #include <linux/platform_device.h>
 20 #include <linux/reboot.h>
 21 #include <linux/watchdog.h>
 22 #include <linux/moduleparam.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         struct notifier_block restart_handler;
 33 };
 34 
 35 static int heartbeat;
 36 
 37 static int moxart_restart_handle(struct notifier_block *this,
 38                                  unsigned long mode, void *cmd)
 39 {
 40         struct moxart_wdt_dev *moxart_wdt = container_of(this,
 41                                                          struct moxart_wdt_dev,
 42                                                          restart_handler);
 43         writel(1, moxart_wdt->base + REG_COUNT);
 44         writel(0x5ab9, moxart_wdt->base + REG_MODE);
 45         writel(0x03, moxart_wdt->base + REG_ENABLE);
 46 
 47         return NOTIFY_DONE;
 48 }
 49 
 50 static int moxart_wdt_stop(struct watchdog_device *wdt_dev)
 51 {
 52         struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
 53 
 54         writel(0, moxart_wdt->base + REG_ENABLE);
 55 
 56         return 0;
 57 }
 58 
 59 static int moxart_wdt_start(struct watchdog_device *wdt_dev)
 60 {
 61         struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
 62 
 63         writel(moxart_wdt->clock_frequency * wdt_dev->timeout,
 64                moxart_wdt->base + REG_COUNT);
 65         writel(0x5ab9, moxart_wdt->base + REG_MODE);
 66         writel(0x03, moxart_wdt->base + REG_ENABLE);
 67 
 68         return 0;
 69 }
 70 
 71 static int moxart_wdt_set_timeout(struct watchdog_device *wdt_dev,
 72                                   unsigned int timeout)
 73 {
 74         wdt_dev->timeout = timeout;
 75 
 76         return 0;
 77 }
 78 
 79 static const struct watchdog_info moxart_wdt_info = {
 80         .identity       = "moxart-wdt",
 81         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 82                           WDIOF_MAGICCLOSE,
 83 };
 84 
 85 static const struct watchdog_ops moxart_wdt_ops = {
 86         .owner          = THIS_MODULE,
 87         .start          = moxart_wdt_start,
 88         .stop           = moxart_wdt_stop,
 89         .set_timeout    = moxart_wdt_set_timeout,
 90 };
 91 
 92 static int moxart_wdt_probe(struct platform_device *pdev)
 93 {
 94         struct moxart_wdt_dev *moxart_wdt;
 95         struct device *dev = &pdev->dev;
 96         struct device_node *node = dev->of_node;
 97         struct resource *res;
 98         struct clk *clk;
 99         int err;
100         unsigned int max_timeout;
101         bool nowayout = WATCHDOG_NOWAYOUT;
102 
103         moxart_wdt = devm_kzalloc(dev, sizeof(*moxart_wdt), GFP_KERNEL);
104         if (!moxart_wdt)
105                 return -ENOMEM;
106 
107         platform_set_drvdata(pdev, moxart_wdt);
108 
109         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
110         moxart_wdt->base = devm_ioremap_resource(dev, res);
111         if (IS_ERR(moxart_wdt->base))
112                 return PTR_ERR(moxart_wdt->base);
113 
114         clk = of_clk_get(node, 0);
115         if (IS_ERR(clk)) {
116                 pr_err("%s: of_clk_get failed\n", __func__);
117                 return PTR_ERR(clk);
118         }
119 
120         moxart_wdt->clock_frequency = clk_get_rate(clk);
121         if (moxart_wdt->clock_frequency == 0) {
122                 pr_err("%s: incorrect clock frequency\n", __func__);
123                 return -EINVAL;
124         }
125 
126         max_timeout = UINT_MAX / moxart_wdt->clock_frequency;
127 
128         moxart_wdt->dev.info = &moxart_wdt_info;
129         moxart_wdt->dev.ops = &moxart_wdt_ops;
130         moxart_wdt->dev.timeout = max_timeout;
131         moxart_wdt->dev.min_timeout = 1;
132         moxart_wdt->dev.max_timeout = max_timeout;
133         moxart_wdt->dev.parent = dev;
134 
135         watchdog_init_timeout(&moxart_wdt->dev, heartbeat, dev);
136         watchdog_set_nowayout(&moxart_wdt->dev, nowayout);
137 
138         watchdog_set_drvdata(&moxart_wdt->dev, moxart_wdt);
139 
140         err = watchdog_register_device(&moxart_wdt->dev);
141         if (err)
142                 return err;
143 
144         moxart_wdt->restart_handler.notifier_call = moxart_restart_handle;
145         moxart_wdt->restart_handler.priority = 128;
146         err = register_restart_handler(&moxart_wdt->restart_handler);
147         if (err)
148                 dev_err(dev, "cannot register restart notifier (err=%d)\n",
149                         err);
150 
151         dev_dbg(dev, "Watchdog enabled (heartbeat=%d sec, nowayout=%d)\n",
152                 moxart_wdt->dev.timeout, nowayout);
153 
154         return 0;
155 }
156 
157 static int moxart_wdt_remove(struct platform_device *pdev)
158 {
159         struct moxart_wdt_dev *moxart_wdt = platform_get_drvdata(pdev);
160 
161         unregister_restart_handler(&moxart_wdt->restart_handler);
162         moxart_wdt_stop(&moxart_wdt->dev);
163 
164         return 0;
165 }
166 
167 static const struct of_device_id moxart_watchdog_match[] = {
168         { .compatible = "moxa,moxart-watchdog" },
169         { },
170 };
171 
172 static struct platform_driver moxart_wdt_driver = {
173         .probe      = moxart_wdt_probe,
174         .remove     = moxart_wdt_remove,
175         .driver     = {
176                 .name           = "moxart-watchdog",
177                 .owner          = THIS_MODULE,
178                 .of_match_table = moxart_watchdog_match,
179         },
180 };
181 module_platform_driver(moxart_wdt_driver);
182 
183 module_param(heartbeat, int, 0);
184 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds");
185 
186 MODULE_DESCRIPTION("MOXART watchdog driver");
187 MODULE_LICENSE("GPL");
188 MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");
189 

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