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/watchdog.h>
  21 #include <linux/of_device.h>
  22
  23 enum wdt_reg {
  24         WDT_RST,
  25         WDT_EN,
  26         WDT_STS,
  27         WDT_BARK_TIME,
  28         WDT_BITE_TIME,
  29 };
  30
  31 static const u32 reg_offset_data_apcs_tmr[] = {
  32         [WDT_RST] = 0x38,
  33         [WDT_EN] = 0x40,
  34         [WDT_STS] = 0x44,
  35         [WDT_BARK_TIME] = 0x4C,
  36         [WDT_BITE_TIME] = 0x5C,
  37 };
  38
  39 static const u32 reg_offset_data_kpss[] = {
  40         [WDT_RST] = 0x4,
  41         [WDT_EN] = 0x8,
  42         [WDT_STS] = 0xC,
  43         [WDT_BARK_TIME] = 0x10,
  44         [WDT_BITE_TIME] = 0x14,
  45 };
  46
  47 struct qcom_wdt {
  48         struct watchdog_device  wdd;
  49         struct clk              *clk;
  50         unsigned long           rate;
  51         void __iomem            *base;
  52         const u32               *layout;
  53 };
  54
  55 static void __iomem *wdt_addr(struct qcom_wdt *wdt, enum wdt_reg reg)
  56 {
  57         return wdt->base + wdt->layout[reg];
  58 }
  59
  60 static inline
  61 struct qcom_wdt *to_qcom_wdt(struct watchdog_device *wdd)
  62 {
  63         return container_of(wdd, struct qcom_wdt, wdd);
  64 }
  65
  66 static int qcom_wdt_start(struct watchdog_device *wdd)
  67 {
  68         struct qcom_wdt *wdt = to_qcom_wdt(wdd);
  69
  70         writel(0, wdt_addr(wdt, WDT_EN));
  71         writel(1, wdt_addr(wdt, WDT_RST));
  72         writel(wdd->timeout * wdt->rate, wdt_addr(wdt, WDT_BARK_TIME));
  73         writel(wdd->timeout * wdt->rate, wdt_addr(wdt, WDT_BITE_TIME));
  74         writel(1, wdt_addr(wdt, WDT_EN));
  75         return 0;
  76 }
  77
  78 static int qcom_wdt_stop(struct watchdog_device *wdd)
  79 {
  80         struct qcom_wdt *wdt = to_qcom_wdt(wdd);
  81
  82         writel(0, wdt_addr(wdt, WDT_EN));
  83         return 0;
  84 }
  85
  86 static int qcom_wdt_ping(struct watchdog_device *wdd)
  87 {
  88         struct qcom_wdt *wdt = to_qcom_wdt(wdd);
  89
  90         writel(1, wdt_addr(wdt, WDT_RST));
  91         return 0;
  92 }
  93
  94 static int qcom_wdt_set_timeout(struct watchdog_device *wdd,
  95                                 unsigned int timeout)
  96 {
  97         wdd->timeout = timeout;
  98         return qcom_wdt_start(wdd);
  99 }
 100
 101 static int qcom_wdt_restart(struct watchdog_device *wdd, unsigned long action,
 102                             void *data)
 103 {
 104         struct qcom_wdt *wdt = to_qcom_wdt(wdd);
 105         u32 timeout;
 106
 107         /*
 108          * Trigger watchdog bite:
 109          *    Setup BITE_TIME to be 128ms, and enable WDT.
 110          */
 111         timeout = 128 * wdt->rate / 1000;
 112
 113         writel(0, wdt_addr(wdt, WDT_EN));
 114         writel(1, wdt_addr(wdt, WDT_RST));
 115         writel(timeout, wdt_addr(wdt, WDT_BARK_TIME));
 116         writel(timeout, wdt_addr(wdt, WDT_BITE_TIME));
 117         writel(1, wdt_addr(wdt, WDT_EN));
 118
 119         /*
 120          * Actually make sure the above sequence hits hardware before sleeping.
 121          */
 122         wmb();
 123
 124         msleep(150);
 125         return 0;
 126 }
 127
 128 static const struct watchdog_ops qcom_wdt_ops = {
 129         .start          = qcom_wdt_start,
 130         .stop           = qcom_wdt_stop,
 131         .ping           = qcom_wdt_ping,
 132         .set_timeout    = qcom_wdt_set_timeout,
 133         .restart        = qcom_wdt_restart,
 134         .owner          = THIS_MODULE,
 135 };
 136
 137 static const struct watchdog_info qcom_wdt_info = {
 138         .options        = WDIOF_KEEPALIVEPING
 139                         | WDIOF_MAGICCLOSE
 140                         | WDIOF_SETTIMEOUT
 141                         | WDIOF_CARDRESET,
 142         .identity       = KBUILD_MODNAME,
 143 };
 144
 145 static int qcom_wdt_probe(struct platform_device *pdev)
 146 {
 147         struct qcom_wdt *wdt;
 148         struct resource *res;
 149         struct device_node *np = pdev->dev.of_node;
 150         const u32 *regs;
 151         u32 percpu_offset;
 152         int ret;
 153
 154         regs = of_device_get_match_data(&pdev->dev);
 155         if (!regs) {
 156                 dev_err(&pdev->dev, "Unsupported QCOM WDT module\n");
 157                 return -ENODEV;
 158         }
 159
 160         wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
 161         if (!wdt)
 162                 return -ENOMEM;
 163
 164         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 165         if (!res)
 166                 return -ENOMEM;
 167
 168         /* We use CPU0's DGT for the watchdog */
 169         if (of_property_read_u32(np, "cpu-offset", &percpu_offset))
 170                 percpu_offset = 0;
 171
 172         res->start += percpu_offset;
 173         res->end += percpu_offset;
 174
 175         wdt->base = devm_ioremap_resource(&pdev->dev, res);
 176         if (IS_ERR(wdt->base))
 177                 return PTR_ERR(wdt->base);
 178
 179         wdt->clk = devm_clk_get(&pdev->dev, NULL);
 180         if (IS_ERR(wdt->clk)) {
 181                 dev_err(&pdev->dev, "failed to get input clock\n");
 182                 return PTR_ERR(wdt->clk);
 183         }
 184
 185         ret = clk_prepare_enable(wdt->clk);
 186         if (ret) {
 187                 dev_err(&pdev->dev, "failed to setup clock\n");
 188                 return ret;
 189         }
 190
 191         /*
 192          * We use the clock rate to calculate the max timeout, so ensure it's
 193          * not zero to avoid a divide-by-zero exception.
 194          *
 195          * WATCHDOG_CORE assumes units of seconds, if the WDT is clocked such
 196          * that it would bite before a second elapses it's usefulness is
 197          * limited.  Bail if this is the case.
 198          */
 199         wdt->rate = clk_get_rate(wdt->clk);
 200         if (wdt->rate == 0 ||
 201             wdt->rate > 0x10000000U) {
 202                 dev_err(&pdev->dev, "invalid clock rate\n");
 203                 ret = -EINVAL;
 204                 goto err_clk_unprepare;
 205         }
 206
 207         wdt->wdd.info = &qcom_wdt_info;
 208         wdt->wdd.ops = &qcom_wdt_ops;
 209         wdt->wdd.min_timeout = 1;
 210         wdt->wdd.max_timeout = 0x10000000U / wdt->rate;
 211         wdt->wdd.parent = &pdev->dev;
 212         wdt->layout = regs;
 213
 214         if (readl(wdt_addr(wdt, WDT_STS)) & 1)
 215                 wdt->wdd.bootstatus = WDIOF_CARDRESET;
 216
 217         /*
 218          * If 'timeout-sec' unspecified in devicetree, assume a 30 second
 219          * default, unless the max timeout is less than 30 seconds, then use
 220          * the max instead.
 221          */
 222         wdt->wdd.timeout = min(wdt->wdd.max_timeout, 30U);
 223         watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev);
 224
 225         ret = watchdog_register_device(&wdt->wdd);
 226         if (ret) {
 227                 dev_err(&pdev->dev, "failed to register watchdog\n");
 228                 goto err_clk_unprepare;
 229         }
 230
 231         platform_set_drvdata(pdev, wdt);
 232         return 0;
 233
 234 err_clk_unprepare:
 235         clk_disable_unprepare(wdt->clk);
 236         return ret;
 237 }
 238
 239 static int qcom_wdt_remove(struct platform_device *pdev)
 240 {
 241         struct qcom_wdt *wdt = platform_get_drvdata(pdev);
 242
 243         watchdog_unregister_device(&wdt->wdd);
 244         clk_disable_unprepare(wdt->clk);
 245         return 0;
 246 }
 247
 248 static const struct of_device_id qcom_wdt_of_table[] = {
 249         { .compatible = "qcom,kpss-timer", .data = reg_offset_data_apcs_tmr },
 250         { .compatible = "qcom,scss-timer", .data = reg_offset_data_apcs_tmr },
 251         { .compatible = "qcom,kpss-wdt", .data = reg_offset_data_kpss },
 252         { },
 253 };
 254 MODULE_DEVICE_TABLE(of, qcom_wdt_of_table);
 255
 256 static struct platform_driver qcom_watchdog_driver = {
 257         .probe  = qcom_wdt_probe,
 258         .remove = qcom_wdt_remove,
 259         .driver = {
 260                 .name           = KBUILD_MODNAME,
 261                 .of_match_table = qcom_wdt_of_table,
 262         },
 263 };
 264 module_platform_driver(qcom_watchdog_driver);
 265
 266 MODULE_DESCRIPTION("QCOM KPSS Watchdog Driver");
 267 MODULE_LICENSE("GPL v2");