drivers/watchdog/sunplus_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * sunplus Watchdog Driver
   4  *
   5  * Copyright (C) 2021 Sunplus Technology Co., Ltd.
   6  *
   7  */
   8
   9 #include <linux/clk.h>
  10 #include <linux/io.h>
  11 #include <linux/module.h>
  12 #include <linux/mod_devicetable.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/reset.h>
  15 #include <linux/watchdog.h>
  16
  17 #define WDT_CTRL                0x00
  18 #define WDT_CNT                 0x04
  19
  20 #define WDT_STOP                0x3877
  21 #define WDT_RESUME              0x4A4B
  22 #define WDT_CLRIRQ              0x7482
  23 #define WDT_UNLOCK              0xAB00
  24 #define WDT_LOCK                0xAB01
  25 #define WDT_CONMAX              0xDEAF
  26
  27 /* TIMEOUT_MAX = ffff0/90kHz =11.65, so longer than 11 seconds will time out. */
  28 #define SP_WDT_MAX_TIMEOUT      11U
  29 #define SP_WDT_DEFAULT_TIMEOUT  10
  30
  31 #define STC_CLK                 90000
  32
  33 #define DEVICE_NAME             "sunplus-wdt"
  34
  35 static unsigned int timeout;
  36 module_param(timeout, int, 0);
  37 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
  38
  39 static bool nowayout = WATCHDOG_NOWAYOUT;
  40 module_param(nowayout, bool, 0);
  41 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  42                         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  43
  44 struct sp_wdt_priv {
  45         struct watchdog_device wdev;
  46         void __iomem *base;
  47         struct clk *clk;
  48         struct reset_control *rstc;
  49 };
  50
  51 static int sp_wdt_restart(struct watchdog_device *wdev,
  52                           unsigned long action, void *data)
  53 {
  54         struct sp_wdt_priv *priv = watchdog_get_drvdata(wdev);
  55         void __iomem *base = priv->base;
  56
  57         writel(WDT_STOP, base + WDT_CTRL);
  58         writel(WDT_UNLOCK, base + WDT_CTRL);
  59         writel(0x0001, base + WDT_CNT);
  60         writel(WDT_LOCK, base + WDT_CTRL);
  61         writel(WDT_RESUME, base + WDT_CTRL);
  62
  63         return 0;
  64 }
  65
  66 static int sp_wdt_ping(struct watchdog_device *wdev)
  67 {
  68         struct sp_wdt_priv *priv = watchdog_get_drvdata(wdev);
  69         void __iomem *base = priv->base;
  70         u32 count;
  71
  72         if (wdev->timeout > SP_WDT_MAX_TIMEOUT) {
  73                 /* WDT_CONMAX sets the count to the maximum (down-counting). */
  74                 writel(WDT_CONMAX, base + WDT_CTRL);
  75         } else {
  76                 writel(WDT_UNLOCK, base + WDT_CTRL);
  77                 /*
  78                  * Watchdog timer is a 20-bit down-counting based on STC_CLK.
  79                  * This register bits[16:0] is from bit[19:4] of the watchdog
  80                  * timer counter.
  81                  */
  82                 count = (wdev->timeout * STC_CLK) >> 4;
  83                 writel(count, base + WDT_CNT);
  84                 writel(WDT_LOCK, base + WDT_CTRL);
  85         }
  86
  87         return 0;
  88 }
  89
  90 static int sp_wdt_stop(struct watchdog_device *wdev)
  91 {
  92         struct sp_wdt_priv *priv = watchdog_get_drvdata(wdev);
  93         void __iomem *base = priv->base;
  94
  95         writel(WDT_STOP, base + WDT_CTRL);
  96
  97         return 0;
  98 }
  99
 100 static int sp_wdt_start(struct watchdog_device *wdev)
 101 {
 102         struct sp_wdt_priv *priv = watchdog_get_drvdata(wdev);
 103         void __iomem *base = priv->base;
 104
 105         writel(WDT_RESUME, base + WDT_CTRL);
 106
 107         return 0;
 108 }
 109
 110 static unsigned int sp_wdt_get_timeleft(struct watchdog_device *wdev)
 111 {
 112         struct sp_wdt_priv *priv = watchdog_get_drvdata(wdev);
 113         void __iomem *base = priv->base;
 114         u32 val;
 115
 116         val = readl(base + WDT_CNT);
 117         val &= 0xffff;
 118         val = val << 4;
 119
 120         return val;
 121 }
 122
 123 static const struct watchdog_info sp_wdt_info = {
 124         .identity       = DEVICE_NAME,
 125         .options        = WDIOF_SETTIMEOUT |
 126                           WDIOF_MAGICCLOSE |
 127                           WDIOF_KEEPALIVEPING,
 128 };
 129
 130 static const struct watchdog_ops sp_wdt_ops = {
 131         .owner          = THIS_MODULE,
 132         .start          = sp_wdt_start,
 133         .stop           = sp_wdt_stop,
 134         .ping           = sp_wdt_ping,
 135         .get_timeleft   = sp_wdt_get_timeleft,
 136         .restart        = sp_wdt_restart,
 137 };
 138
 139 static void sp_reset_control_assert(void *data)
 140 {
 141         reset_control_assert(data);
 142 }
 143
 144 static int sp_wdt_probe(struct platform_device *pdev)
 145 {
 146         struct device *dev = &pdev->dev;
 147         struct sp_wdt_priv *priv;
 148         int ret;
 149
 150         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 151         if (!priv)
 152                 return -ENOMEM;
 153
 154         priv->clk = devm_clk_get_enabled(dev, NULL);
 155         if (IS_ERR(priv->clk))
 156                 return dev_err_probe(dev, PTR_ERR(priv->clk), "Failed to enable clock\n");
 157
 158         /* The timer and watchdog shared the STC reset */
 159         priv->rstc = devm_reset_control_get_shared(dev, NULL);
 160         if (IS_ERR(priv->rstc))
 161                 return dev_err_probe(dev, PTR_ERR(priv->rstc), "Failed to get reset\n");
 162
 163         reset_control_deassert(priv->rstc);
 164
 165         ret = devm_add_action_or_reset(dev, sp_reset_control_assert, priv->rstc);
 166         if (ret)
 167                 return ret;
 168
 169         priv->base = devm_platform_ioremap_resource(pdev, 0);
 170         if (IS_ERR(priv->base))
 171                 return PTR_ERR(priv->base);
 172
 173         priv->wdev.info = &sp_wdt_info;
 174         priv->wdev.ops = &sp_wdt_ops;
 175         priv->wdev.timeout = SP_WDT_DEFAULT_TIMEOUT;
 176         priv->wdev.max_hw_heartbeat_ms = SP_WDT_MAX_TIMEOUT * 1000;
 177         priv->wdev.min_timeout = 1;
 178         priv->wdev.parent = dev;
 179
 180         watchdog_set_drvdata(&priv->wdev, priv);
 181         watchdog_init_timeout(&priv->wdev, timeout, dev);
 182         watchdog_set_nowayout(&priv->wdev, nowayout);
 183         watchdog_stop_on_reboot(&priv->wdev);
 184         watchdog_set_restart_priority(&priv->wdev, 128);
 185
 186         return devm_watchdog_register_device(dev, &priv->wdev);
 187 }
 188
 189 static const struct of_device_id sp_wdt_of_match[] = {
 190         {.compatible = "sunplus,sp7021-wdt", },
 191         { /* sentinel */ }
 192 };
 193 MODULE_DEVICE_TABLE(of, sp_wdt_of_match);
 194
 195 static struct platform_driver sp_wdt_driver = {
 196         .probe = sp_wdt_probe,
 197         .driver = {
 198                    .name = DEVICE_NAME,
 199                    .of_match_table = sp_wdt_of_match,
 200         },
 201 };
 202
 203 module_platform_driver(sp_wdt_driver);
 204
 205 MODULE_AUTHOR("Xiantao Hu <xt.hu@cqplus1.com>");
 206 MODULE_DESCRIPTION("Sunplus Watchdog Timer Driver");
 207 MODULE_LICENSE("GPL");