drivers/watchdog/qcom-wdt.c

   1 /* Copyright (c) 2014, The Linux Foundation. All rights reserved.
   2  *
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License version 2 and
   5  * only version 2 as published by the Free Software Foundation.
   6  *
   7  * This program is distributed in the hope that it will be useful,
   8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10  * GNU General Public License for more details.
  11  *
  12  */
  13 #include <linux/clk.h>
  14 #include <linux/delay.h>
  15 #include <linux/io.h>
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/of.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/reboot.h>
  21 #include <linux/watchdog.h>
  22
  23 #define WDT_RST         0x38
  24 #define WDT_EN          0x40
  25 #define WDT_BITE_TIME   0x5C
  26
  27 struct qcom_wdt {
  28         struct watchdog_device  wdd;
  29         struct clk              *clk;
  30         unsigned long           rate;
  31         struct notifier_block   restart_nb;
  32         void __iomem            *base;
  33 };
  34
  35 static inline
  36 struct qcom_wdt *to_qcom_wdt(struct watchdog_device *wdd)
  37 {
  38         return container_of(wdd, struct qcom_wdt, wdd);
  39 }
  40
  41 static int qcom_wdt_start(struct watchdog_device *wdd)
  42 {
  43         struct qcom_wdt *wdt = to_qcom_wdt(wdd);
  44
  45         writel(0, wdt->base + WDT_EN);
  46         writel(1, wdt->base + WDT_RST);
  47         writel(wdd->timeout * wdt->rate, wdt->base + WDT_BITE_TIME);
  48         writel(1, wdt->base + WDT_EN);
  49         return 0;
  50 }
  51
  52 static int qcom_wdt_stop(struct watchdog_device *wdd)
  53 {
  54         struct qcom_wdt *wdt = to_qcom_wdt(wdd);
  55
  56         writel(0, wdt->base + WDT_EN);
  57         return 0;
  58 }
  59
  60 static int qcom_wdt_ping(struct watchdog_device *wdd)
  61 {
  62         struct qcom_wdt *wdt = to_qcom_wdt(wdd);
  63
  64         writel(1, wdt->base + WDT_RST);
  65         return 0;
  66 }
  67
  68 static int qcom_wdt_set_timeout(struct watchdog_device *wdd,
  69                                 unsigned int timeout)
  70 {
  71         wdd->timeout = timeout;
  72         return qcom_wdt_start(wdd);
  73 }
  74
  75 static const struct watchdog_ops qcom_wdt_ops = {
  76         .start          = qcom_wdt_start,
  77         .stop           = qcom_wdt_stop,
  78         .ping           = qcom_wdt_ping,
  79         .set_timeout    = qcom_wdt_set_timeout,
  80         .owner          = THIS_MODULE,
  81 };
  82
  83 static const struct watchdog_info qcom_wdt_info = {
  84         .options        = WDIOF_KEEPALIVEPING
  85                         | WDIOF_MAGICCLOSE
  86                         | WDIOF_SETTIMEOUT,
  87         .identity       = KBUILD_MODNAME,
  88 };
  89
  90 static int qcom_wdt_restart(struct notifier_block *nb, unsigned long action,
  91                             void *data)
  92 {
  93         struct qcom_wdt *wdt = container_of(nb, struct qcom_wdt, restart_nb);
  94         u32 timeout;
  95
  96         /*
  97          * Trigger watchdog bite:
  98          *    Setup BITE_TIME to be 128ms, and enable WDT.
  99          */
 100         timeout = 128 * wdt->rate / 1000;
 101
 102         writel(0, wdt->base + WDT_EN);
 103         writel(1, wdt->base + WDT_RST);
 104         writel(timeout, wdt->base + WDT_BITE_TIME);
 105         writel(1, wdt->base + WDT_EN);
 106
 107         /*
 108          * Actually make sure the above sequence hits hardware before sleeping.
 109          */
 110         wmb();
 111
 112         msleep(150);
 113         return NOTIFY_DONE;
 114 }
 115
 116 static int qcom_wdt_probe(struct platform_device *pdev)
 117 {
 118         struct qcom_wdt *wdt;
 119         struct resource *res;
 120         struct device_node *np = pdev->dev.of_node;
 121         u32 percpu_offset;
 122         int ret;
 123
 124         wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
 125         if (!wdt)
 126                 return -ENOMEM;
 127
 128         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 129
 130         /* We use CPU0's DGT for the watchdog */
 131         if (of_property_read_u32(np, "cpu-offset", &percpu_offset))
 132                 percpu_offset = 0;
 133
 134         res->start += percpu_offset;
 135         res->end += percpu_offset;
 136
 137         wdt->base = devm_ioremap_resource(&pdev->dev, res);
 138         if (IS_ERR(wdt->base))
 139                 return PTR_ERR(wdt->base);
 140
 141         wdt->clk = devm_clk_get(&pdev->dev, NULL);
 142         if (IS_ERR(wdt->clk)) {
 143                 dev_err(&pdev->dev, "failed to get input clock\n");
 144                 return PTR_ERR(wdt->clk);
 145         }
 146
 147         ret = clk_prepare_enable(wdt->clk);
 148         if (ret) {
 149                 dev_err(&pdev->dev, "failed to setup clock\n");
 150                 return ret;
 151         }
 152
 153         /*
 154          * We use the clock rate to calculate the max timeout, so ensure it's
 155          * not zero to avoid a divide-by-zero exception.
 156          *
 157          * WATCHDOG_CORE assumes units of seconds, if the WDT is clocked such
 158          * that it would bite before a second elapses it's usefulness is
 159          * limited.  Bail if this is the case.
 160          */
 161         wdt->rate = clk_get_rate(wdt->clk);
 162         if (wdt->rate == 0 ||
 163             wdt->rate > 0x10000000U) {
 164                 dev_err(&pdev->dev, "invalid clock rate\n");
 165                 ret = -EINVAL;
 166                 goto err_clk_unprepare;
 167         }
 168
 169         wdt->wdd.dev = &pdev->dev;
 170         wdt->wdd.info = &qcom_wdt_info;
 171         wdt->wdd.ops = &qcom_wdt_ops;
 172         wdt->wdd.min_timeout = 1;
 173         wdt->wdd.max_timeout = 0x10000000U / wdt->rate;
 174         wdt->wdd.parent = &pdev->dev;
 175
 176         /*
 177          * If 'timeout-sec' unspecified in devicetree, assume a 30 second
 178          * default, unless the max timeout is less than 30 seconds, then use
 179          * the max instead.
 180          */
 181         wdt->wdd.timeout = min(wdt->wdd.max_timeout, 30U);
 182         watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev);
 183
 184         ret = watchdog_register_device(&wdt->wdd);
 185         if (ret) {
 186                 dev_err(&pdev->dev, "failed to register watchdog\n");
 187                 goto err_clk_unprepare;
 188         }
 189
 190         /*
 191          * WDT restart notifier has priority 0 (use as a last resort)
 192          */
 193         wdt->restart_nb.notifier_call = qcom_wdt_restart;
 194         ret = register_restart_handler(&wdt->restart_nb);
 195         if (ret)
 196                 dev_err(&pdev->dev, "failed to setup restart handler\n");
 197
 198         platform_set_drvdata(pdev, wdt);
 199         return 0;
 200
 201 err_clk_unprepare:
 202         clk_disable_unprepare(wdt->clk);
 203         return ret;
 204 }
 205
 206 static int qcom_wdt_remove(struct platform_device *pdev)
 207 {
 208         struct qcom_wdt *wdt = platform_get_drvdata(pdev);
 209
 210         unregister_restart_handler(&wdt->restart_nb);
 211         watchdog_unregister_device(&wdt->wdd);
 212         clk_disable_unprepare(wdt->clk);
 213         return 0;
 214 }
 215
 216 static const struct of_device_id qcom_wdt_of_table[] = {
 217         { .compatible = "qcom,kpss-timer" },
 218         { .compatible = "qcom,scss-timer" },
 219         { },
 220 };
 221 MODULE_DEVICE_TABLE(of, qcom_wdt_of_table);
 222
 223 static struct platform_driver qcom_watchdog_driver = {
 224         .probe  = qcom_wdt_probe,
 225         .remove = qcom_wdt_remove,
 226         .driver = {
 227                 .name           = KBUILD_MODNAME,
 228                 .of_match_table = qcom_wdt_of_table,
 229         },
 230 };
 231 module_platform_driver(qcom_watchdog_driver);
 232
 233 MODULE_DESCRIPTION("QCOM KPSS Watchdog Driver");
 234 MODULE_LICENSE("GPL v2");