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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 #define REG_COUNT                       0x4
 23 #define REG_MODE                        0x8
 24 #define REG_ENABLE                      0xC
 25 
 26 struct moxart_wdt_dev {
 27         struct watchdog_device dev;
 28         void __iomem *base;
 29         unsigned int clock_frequency;
 30 };
 31 
 32 static int heartbeat;
 33 
 34 static int moxart_wdt_restart(struct watchdog_device *wdt_dev)
 35 {
 36         struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
 37 
 38         writel(1, moxart_wdt->base + REG_COUNT);
 39         writel(0x5ab9, moxart_wdt->base + REG_MODE);
 40         writel(0x03, moxart_wdt->base + REG_ENABLE);
 41 
 42         return 0;
 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         .restart        = moxart_wdt_restart,
 86 };
 87 
 88 static int moxart_wdt_probe(struct platform_device *pdev)
 89 {
 90         struct moxart_wdt_dev *moxart_wdt;
 91         struct device *dev = &pdev->dev;
 92         struct device_node *node = dev->of_node;
 93         struct resource *res;
 94         struct clk *clk;
 95         int err;
 96         unsigned int max_timeout;
 97         bool nowayout = WATCHDOG_NOWAYOUT;
 98 
 99         moxart_wdt = devm_kzalloc(dev, sizeof(*moxart_wdt), GFP_KERNEL);
100         if (!moxart_wdt)
101                 return -ENOMEM;
102 
103         platform_set_drvdata(pdev, moxart_wdt);
104 
105         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
106         moxart_wdt->base = devm_ioremap_resource(dev, res);
107         if (IS_ERR(moxart_wdt->base))
108                 return PTR_ERR(moxart_wdt->base);
109 
110         clk = of_clk_get(node, 0);
111         if (IS_ERR(clk)) {
112                 pr_err("%s: of_clk_get failed\n", __func__);
113                 return PTR_ERR(clk);
114         }
115 
116         moxart_wdt->clock_frequency = clk_get_rate(clk);
117         if (moxart_wdt->clock_frequency == 0) {
118                 pr_err("%s: incorrect clock frequency\n", __func__);
119                 return -EINVAL;
120         }
121 
122         max_timeout = UINT_MAX / moxart_wdt->clock_frequency;
123 
124         moxart_wdt->dev.info = &moxart_wdt_info;
125         moxart_wdt->dev.ops = &moxart_wdt_ops;
126         moxart_wdt->dev.timeout = max_timeout;
127         moxart_wdt->dev.min_timeout = 1;
128         moxart_wdt->dev.max_timeout = max_timeout;
129         moxart_wdt->dev.parent = dev;
130 
131         watchdog_init_timeout(&moxart_wdt->dev, heartbeat, dev);
132         watchdog_set_nowayout(&moxart_wdt->dev, nowayout);
133         watchdog_set_restart_priority(&moxart_wdt->dev, 128);
134 
135         watchdog_set_drvdata(&moxart_wdt->dev, moxart_wdt);
136 
137         err = watchdog_register_device(&moxart_wdt->dev);
138         if (err)
139                 return err;
140 
141         dev_dbg(dev, "Watchdog enabled (heartbeat=%d sec, nowayout=%d)\n",
142                 moxart_wdt->dev.timeout, nowayout);
143 
144         return 0;
145 }
146 
147 static int moxart_wdt_remove(struct platform_device *pdev)
148 {
149         struct moxart_wdt_dev *moxart_wdt = platform_get_drvdata(pdev);
150 
151         moxart_wdt_stop(&moxart_wdt->dev);
152 
153         return 0;
154 }
155 
156 static const struct of_device_id moxart_watchdog_match[] = {
157         { .compatible = "moxa,moxart-watchdog" },
158         { },
159 };
160 MODULE_DEVICE_TABLE(of, moxart_watchdog_match);
161 
162 static struct platform_driver moxart_wdt_driver = {
163         .probe      = moxart_wdt_probe,
164         .remove     = moxart_wdt_remove,
165         .driver     = {
166                 .name           = "moxart-watchdog",
167                 .of_match_table = moxart_watchdog_match,
168         },
169 };
170 module_platform_driver(moxart_wdt_driver);
171 
172 module_param(heartbeat, int, 0);
173 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds");
174 
175 MODULE_DESCRIPTION("MOXART watchdog driver");
176 MODULE_LICENSE("GPL");
177 MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");
178 

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