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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                               unsigned long action, void *data)
 36 {
 37         struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
 38 
 39         writel(1, moxart_wdt->base + REG_COUNT);
 40         writel(0x5ab9, moxart_wdt->base + REG_MODE);
 41         writel(0x03, moxart_wdt->base + REG_ENABLE);
 42 
 43         return 0;
 44 }
 45 
 46 static int moxart_wdt_stop(struct watchdog_device *wdt_dev)
 47 {
 48         struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
 49 
 50         writel(0, moxart_wdt->base + REG_ENABLE);
 51 
 52         return 0;
 53 }
 54 
 55 static int moxart_wdt_start(struct watchdog_device *wdt_dev)
 56 {
 57         struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
 58 
 59         writel(moxart_wdt->clock_frequency * wdt_dev->timeout,
 60                moxart_wdt->base + REG_COUNT);
 61         writel(0x5ab9, moxart_wdt->base + REG_MODE);
 62         writel(0x03, moxart_wdt->base + REG_ENABLE);
 63 
 64         return 0;
 65 }
 66 
 67 static int moxart_wdt_set_timeout(struct watchdog_device *wdt_dev,
 68                                   unsigned int timeout)
 69 {
 70         wdt_dev->timeout = timeout;
 71 
 72         return 0;
 73 }
 74 
 75 static const struct watchdog_info moxart_wdt_info = {
 76         .identity       = "moxart-wdt",
 77         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 78                           WDIOF_MAGICCLOSE,
 79 };
 80 
 81 static const struct watchdog_ops moxart_wdt_ops = {
 82         .owner          = THIS_MODULE,
 83         .start          = moxart_wdt_start,
 84         .stop           = moxart_wdt_stop,
 85         .set_timeout    = moxart_wdt_set_timeout,
 86         .restart        = moxart_wdt_restart,
 87 };
 88 
 89 static int moxart_wdt_probe(struct platform_device *pdev)
 90 {
 91         struct moxart_wdt_dev *moxart_wdt;
 92         struct device *dev = &pdev->dev;
 93         struct device_node *node = dev->of_node;
 94         struct resource *res;
 95         struct clk *clk;
 96         int err;
 97         unsigned int max_timeout;
 98         bool nowayout = WATCHDOG_NOWAYOUT;
 99 
100         moxart_wdt = devm_kzalloc(dev, sizeof(*moxart_wdt), GFP_KERNEL);
101         if (!moxart_wdt)
102                 return -ENOMEM;
103 
104         platform_set_drvdata(pdev, moxart_wdt);
105 
106         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
107         moxart_wdt->base = devm_ioremap_resource(dev, res);
108         if (IS_ERR(moxart_wdt->base))
109                 return PTR_ERR(moxart_wdt->base);
110 
111         clk = of_clk_get(node, 0);
112         if (IS_ERR(clk)) {
113                 pr_err("%s: of_clk_get failed\n", __func__);
114                 return PTR_ERR(clk);
115         }
116 
117         moxart_wdt->clock_frequency = clk_get_rate(clk);
118         if (moxart_wdt->clock_frequency == 0) {
119                 pr_err("%s: incorrect clock frequency\n", __func__);
120                 return -EINVAL;
121         }
122 
123         max_timeout = UINT_MAX / moxart_wdt->clock_frequency;
124 
125         moxart_wdt->dev.info = &moxart_wdt_info;
126         moxart_wdt->dev.ops = &moxart_wdt_ops;
127         moxart_wdt->dev.timeout = max_timeout;
128         moxart_wdt->dev.min_timeout = 1;
129         moxart_wdt->dev.max_timeout = max_timeout;
130         moxart_wdt->dev.parent = dev;
131 
132         watchdog_init_timeout(&moxart_wdt->dev, heartbeat, dev);
133         watchdog_set_nowayout(&moxart_wdt->dev, nowayout);
134         watchdog_set_restart_priority(&moxart_wdt->dev, 128);
135 
136         watchdog_set_drvdata(&moxart_wdt->dev, moxart_wdt);
137 
138         err = watchdog_register_device(&moxart_wdt->dev);
139         if (err)
140                 return err;
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         moxart_wdt_stop(&moxart_wdt->dev);
153 
154         return 0;
155 }
156 
157 static const struct of_device_id moxart_watchdog_match[] = {
158         { .compatible = "moxa,moxart-watchdog" },
159         { },
160 };
161 MODULE_DEVICE_TABLE(of, moxart_watchdog_match);
162 
163 static struct platform_driver moxart_wdt_driver = {
164         .probe      = moxart_wdt_probe,
165         .remove     = moxart_wdt_remove,
166         .driver     = {
167                 .name           = "moxart-watchdog",
168                 .of_match_table = moxart_watchdog_match,
169         },
170 };
171 module_platform_driver(moxart_wdt_driver);
172 
173 module_param(heartbeat, int, 0);
174 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds");
175 
176 MODULE_DESCRIPTION("MOXART watchdog driver");
177 MODULE_LICENSE("GPL");
178 MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");
179 

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