drivers/watchdog/visconti_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2020 TOSHIBA CORPORATION
   4  * Copyright (c) 2020 Toshiba Electronic Devices & Storage Corporation
   5  * Copyright (c) 2020 Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
   6  */
   7
   8 #include <linux/clk.h>
   9 #include <linux/io.h>
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/of.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/watchdog.h>
  15
  16 #define WDT_CNT                 0x00
  17 #define WDT_MIN                 0x04
  18 #define WDT_MAX                 0x08
  19 #define WDT_CTL                 0x0c
  20 #define WDT_CMD                 0x10
  21 #define WDT_CMD_CLEAR           0x4352
  22 #define WDT_CMD_START_STOP      0x5354
  23 #define WDT_DIV                 0x30
  24
  25 #define VISCONTI_WDT_FREQ       2000000 /* 2MHz */
  26 #define WDT_DEFAULT_TIMEOUT     10U /* in seconds */
  27
  28 static bool nowayout = WATCHDOG_NOWAYOUT;
  29 module_param(nowayout, bool, 0);
  30 MODULE_PARM_DESC(
  31         nowayout,
  32         "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT)")");
  33
  34 struct visconti_wdt_priv {
  35         struct watchdog_device wdev;
  36         void __iomem *base;
  37         u32 div;
  38 };
  39
  40 static int visconti_wdt_start(struct watchdog_device *wdev)
  41 {
  42         struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
  43         u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;
  44
  45         writel(priv->div, priv->base + WDT_DIV);
  46         writel(0, priv->base + WDT_MIN);
  47         writel(timeout, priv->base + WDT_MAX);
  48         writel(0, priv->base + WDT_CTL);
  49         writel(WDT_CMD_START_STOP, priv->base + WDT_CMD);
  50
  51         return 0;
  52 }
  53
  54 static int visconti_wdt_stop(struct watchdog_device *wdev)
  55 {
  56         struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
  57
  58         writel(1, priv->base + WDT_CTL);
  59         writel(WDT_CMD_START_STOP, priv->base + WDT_CMD);
  60
  61         return 0;
  62 }
  63
  64 static int visconti_wdt_ping(struct watchdog_device *wdd)
  65 {
  66         struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdd);
  67
  68         writel(WDT_CMD_CLEAR, priv->base + WDT_CMD);
  69
  70         return 0;
  71 }
  72
  73 static unsigned int visconti_wdt_get_timeleft(struct watchdog_device *wdev)
  74 {
  75         struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
  76         u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;
  77         u32 cnt = readl(priv->base + WDT_CNT);
  78
  79         if (timeout <= cnt)
  80                 return 0;
  81         timeout -= cnt;
  82
  83         return timeout / VISCONTI_WDT_FREQ;
  84 }
  85
  86 static int visconti_wdt_set_timeout(struct watchdog_device *wdev, unsigned int timeout)
  87 {
  88         u32 val;
  89         struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
  90
  91         wdev->timeout = timeout;
  92         val = wdev->timeout * VISCONTI_WDT_FREQ;
  93
  94         /* Clear counter before setting timeout because WDT expires */
  95         writel(WDT_CMD_CLEAR, priv->base + WDT_CMD);
  96         writel(val, priv->base + WDT_MAX);
  97
  98         return 0;
  99 }
 100
 101 static const struct watchdog_info visconti_wdt_info = {
 102         .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
 103         .identity = "Visconti Watchdog",
 104 };
 105
 106 static const struct watchdog_ops visconti_wdt_ops = {
 107         .owner          = THIS_MODULE,
 108         .start          = visconti_wdt_start,
 109         .stop           = visconti_wdt_stop,
 110         .ping           = visconti_wdt_ping,
 111         .get_timeleft   = visconti_wdt_get_timeleft,
 112         .set_timeout    = visconti_wdt_set_timeout,
 113 };
 114
 115 static void visconti_clk_disable_unprepare(void *data)
 116 {
 117         clk_disable_unprepare(data);
 118 }
 119
 120 static int visconti_wdt_probe(struct platform_device *pdev)
 121 {
 122         struct watchdog_device *wdev;
 123         struct visconti_wdt_priv *priv;
 124         struct device *dev = &pdev->dev;
 125         struct clk *clk;
 126         int ret;
 127         unsigned long clk_freq;
 128
 129         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 130         if (!priv)
 131                 return -ENOMEM;
 132
 133         priv->base = devm_platform_ioremap_resource(pdev, 0);
 134         if (IS_ERR(priv->base))
 135                 return PTR_ERR(priv->base);
 136
 137         clk = devm_clk_get(dev, NULL);
 138         if (IS_ERR(clk))
 139                 return dev_err_probe(dev, PTR_ERR(clk), "Could not get clock\n");
 140
 141         ret = clk_prepare_enable(clk);
 142         if (ret) {
 143                 dev_err(dev, "Could not enable clock\n");
 144                 return ret;
 145         }
 146
 147         ret = devm_add_action_or_reset(dev, visconti_clk_disable_unprepare, clk);
 148         if (ret)
 149                 return ret;
 150
 151         clk_freq = clk_get_rate(clk);
 152         if (!clk_freq)
 153                 return -EINVAL;
 154
 155         priv->div = clk_freq / VISCONTI_WDT_FREQ;
 156
 157         /* Initialize struct watchdog_device. */
 158         wdev = &priv->wdev;
 159         wdev->info = &visconti_wdt_info;
 160         wdev->ops = &visconti_wdt_ops;
 161         wdev->parent = dev;
 162         wdev->min_timeout = 1;
 163         wdev->max_timeout = 0xffffffff / VISCONTI_WDT_FREQ;
 164         wdev->timeout = min(wdev->max_timeout, WDT_DEFAULT_TIMEOUT);
 165
 166         watchdog_set_drvdata(wdev, priv);
 167         watchdog_set_nowayout(wdev, nowayout);
 168         watchdog_stop_on_unregister(wdev);
 169
 170         /* This overrides the default timeout only if DT configuration was found */
 171         ret = watchdog_init_timeout(wdev, 0, dev);
 172         if (ret)
 173                 dev_warn(dev, "Specified timeout value invalid, using default\n");
 174
 175         return devm_watchdog_register_device(dev, wdev);
 176 }
 177
 178 static const struct of_device_id visconti_wdt_of_match[] = {
 179         { .compatible = "toshiba,visconti-wdt", },
 180         {}
 181 };
 182 MODULE_DEVICE_TABLE(of, visconti_wdt_of_match);
 183
 184 static struct platform_driver visconti_wdt_driver = {
 185         .driver = {
 186                         .name = "visconti_wdt",
 187                         .of_match_table = visconti_wdt_of_match,
 188                 },
 189         .probe = visconti_wdt_probe,
 190 };
 191 module_platform_driver(visconti_wdt_driver);
 192
 193 MODULE_DESCRIPTION("TOSHIBA Visconti Watchdog Driver");
 194 MODULE_AUTHOR("Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp");
 195 MODULE_LICENSE("GPL v2");