drivers/watchdog/atlas7_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Watchdog driver for CSR Atlas7
   4  *
   5  * Copyright (c) 2015 Cambridge Silicon Radio Limited, a CSR plc group company.
   6  */
   7
   8 #include <linux/clk.h>
   9 #include <linux/io.h>
  10 #include <linux/module.h>
  11 #include <linux/moduleparam.h>
  12 #include <linux/of.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/watchdog.h>
  15
  16 #define ATLAS7_TIMER_WDT_INDEX          5
  17 #define ATLAS7_WDT_DEFAULT_TIMEOUT      20
  18
  19 #define ATLAS7_WDT_CNT_CTRL     (0 + 4 * ATLAS7_TIMER_WDT_INDEX)
  20 #define ATLAS7_WDT_CNT_MATCH    (0x18 + 4 * ATLAS7_TIMER_WDT_INDEX)
  21 #define ATLAS7_WDT_CNT          (0x48 +  4 * ATLAS7_TIMER_WDT_INDEX)
  22 #define ATLAS7_WDT_CNT_EN       (BIT(0) | BIT(1))
  23 #define ATLAS7_WDT_EN           0x64
  24
  25 static unsigned int timeout = ATLAS7_WDT_DEFAULT_TIMEOUT;
  26 static bool nowayout = WATCHDOG_NOWAYOUT;
  27
  28 module_param(timeout, uint, 0);
  29 module_param(nowayout, bool, 0);
  30
  31 MODULE_PARM_DESC(timeout, "Default watchdog timeout (in seconds)");
  32 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  33                         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  34
  35 struct atlas7_wdog {
  36         struct device *dev;
  37         void __iomem *base;
  38         unsigned long tick_rate;
  39         struct clk *clk;
  40 };
  41
  42 static unsigned int atlas7_wdt_gettimeleft(struct watchdog_device *wdd)
  43 {
  44         struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
  45         u32 counter, match, delta;
  46
  47         counter = readl(wdt->base + ATLAS7_WDT_CNT);
  48         match = readl(wdt->base + ATLAS7_WDT_CNT_MATCH);
  49         delta = match - counter;
  50
  51         return  delta / wdt->tick_rate;
  52 }
  53
  54 static int atlas7_wdt_ping(struct watchdog_device *wdd)
  55 {
  56         struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
  57         u32 counter, match, delta;
  58
  59         counter = readl(wdt->base + ATLAS7_WDT_CNT);
  60         delta = wdd->timeout * wdt->tick_rate;
  61         match = counter + delta;
  62
  63         writel(match, wdt->base + ATLAS7_WDT_CNT_MATCH);
  64
  65         return 0;
  66 }
  67
  68 static int atlas7_wdt_enable(struct watchdog_device *wdd)
  69 {
  70         struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
  71
  72         atlas7_wdt_ping(wdd);
  73
  74         writel(readl(wdt->base + ATLAS7_WDT_CNT_CTRL) | ATLAS7_WDT_CNT_EN,
  75               wdt->base + ATLAS7_WDT_CNT_CTRL);
  76         writel(1, wdt->base + ATLAS7_WDT_EN);
  77
  78         return 0;
  79 }
  80
  81 static int atlas7_wdt_disable(struct watchdog_device *wdd)
  82 {
  83         struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
  84
  85         writel(0, wdt->base + ATLAS7_WDT_EN);
  86         writel(readl(wdt->base + ATLAS7_WDT_CNT_CTRL) & ~ATLAS7_WDT_CNT_EN,
  87               wdt->base + ATLAS7_WDT_CNT_CTRL);
  88
  89         return 0;
  90 }
  91
  92 static int atlas7_wdt_settimeout(struct watchdog_device *wdd, unsigned int to)
  93 {
  94         wdd->timeout = to;
  95
  96         return 0;
  97 }
  98
  99 #define OPTIONS (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
 100
 101 static const struct watchdog_info atlas7_wdt_ident = {
 102         .options = OPTIONS,
 103         .firmware_version = 0,
 104         .identity = "atlas7 Watchdog",
 105 };
 106
 107 static const struct watchdog_ops atlas7_wdt_ops = {
 108         .owner = THIS_MODULE,
 109         .start = atlas7_wdt_enable,
 110         .stop = atlas7_wdt_disable,
 111         .get_timeleft = atlas7_wdt_gettimeleft,
 112         .ping = atlas7_wdt_ping,
 113         .set_timeout = atlas7_wdt_settimeout,
 114 };
 115
 116 static struct watchdog_device atlas7_wdd = {
 117         .info = &atlas7_wdt_ident,
 118         .ops = &atlas7_wdt_ops,
 119         .timeout = ATLAS7_WDT_DEFAULT_TIMEOUT,
 120 };
 121
 122 static const struct of_device_id atlas7_wdt_ids[] = {
 123         { .compatible = "sirf,atlas7-tick"},
 124         {}
 125 };
 126
 127 static void atlas7_clk_disable_unprepare(void *data)
 128 {
 129         clk_disable_unprepare(data);
 130 }
 131
 132 static int atlas7_wdt_probe(struct platform_device *pdev)
 133 {
 134         struct device *dev = &pdev->dev;
 135         struct atlas7_wdog *wdt;
 136         struct clk *clk;
 137         int ret;
 138
 139         wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 140         if (!wdt)
 141                 return -ENOMEM;
 142         wdt->base = devm_platform_ioremap_resource(pdev, 0);
 143         if (IS_ERR(wdt->base))
 144                 return PTR_ERR(wdt->base);
 145
 146         clk = devm_clk_get(dev, NULL);
 147         if (IS_ERR(clk))
 148                 return PTR_ERR(clk);
 149         ret = clk_prepare_enable(clk);
 150         if (ret) {
 151                 dev_err(dev, "clk enable failed\n");
 152                 return ret;
 153         }
 154         ret = devm_add_action_or_reset(dev, atlas7_clk_disable_unprepare, clk);
 155         if (ret)
 156                 return ret;
 157
 158         /* disable watchdog hardware */
 159         writel(0, wdt->base + ATLAS7_WDT_CNT_CTRL);
 160
 161         wdt->tick_rate = clk_get_rate(clk);
 162         if (!wdt->tick_rate)
 163                 return -EINVAL;
 164
 165         wdt->clk = clk;
 166         atlas7_wdd.min_timeout = 1;
 167         atlas7_wdd.max_timeout = UINT_MAX / wdt->tick_rate;
 168
 169         watchdog_init_timeout(&atlas7_wdd, 0, dev);
 170         watchdog_set_nowayout(&atlas7_wdd, nowayout);
 171
 172         watchdog_set_drvdata(&atlas7_wdd, wdt);
 173         platform_set_drvdata(pdev, &atlas7_wdd);
 174
 175         watchdog_stop_on_reboot(&atlas7_wdd);
 176         watchdog_stop_on_unregister(&atlas7_wdd);
 177         return devm_watchdog_register_device(dev, &atlas7_wdd);
 178 }
 179
 180 static int __maybe_unused atlas7_wdt_suspend(struct device *dev)
 181 {
 182         /*
 183          * NOTE:timer controller registers settings are saved
 184          * and restored back by the timer-atlas7.c
 185          */
 186         return 0;
 187 }
 188
 189 static int __maybe_unused atlas7_wdt_resume(struct device *dev)
 190 {
 191         struct watchdog_device *wdd = dev_get_drvdata(dev);
 192
 193         /*
 194          * NOTE: Since timer controller registers settings are saved
 195          * and restored back by the timer-atlas7.c, so we need not
 196          * update WD settings except refreshing timeout.
 197          */
 198         atlas7_wdt_ping(wdd);
 199
 200         return 0;
 201 }
 202
 203 static SIMPLE_DEV_PM_OPS(atlas7_wdt_pm_ops,
 204                 atlas7_wdt_suspend, atlas7_wdt_resume);
 205
 206 MODULE_DEVICE_TABLE(of, atlas7_wdt_ids);
 207
 208 static struct platform_driver atlas7_wdt_driver = {
 209         .driver = {
 210                 .name = "atlas7-wdt",
 211                 .pm = &atlas7_wdt_pm_ops,
 212                 .of_match_table = atlas7_wdt_ids,
 213         },
 214         .probe = atlas7_wdt_probe,
 215 };
 216 module_platform_driver(atlas7_wdt_driver);
 217
 218 MODULE_DESCRIPTION("CSRatlas7 watchdog driver");
 219 MODULE_AUTHOR("Guo Zeng <Guo.Zeng@csr.com>");
 220 MODULE_LICENSE("GPL v2");
 221 MODULE_ALIAS("platform:atlas7-wdt");