drivers/watchdog/imx7ulp_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright 2019 NXP.
   4  */
   5
   6 #include <linux/clk.h>
   7 #include <linux/init.h>
   8 #include <linux/io.h>
   9 #include <linux/kernel.h>
  10 #include <linux/module.h>
  11 #include <linux/of.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/reboot.h>
  14 #include <linux/watchdog.h>
  15
  16 #define WDOG_CS                 0x0
  17 #define WDOG_CS_CMD32EN         BIT(13)
  18 #define WDOG_CS_ULK             BIT(11)
  19 #define WDOG_CS_RCS             BIT(10)
  20 #define LPO_CLK                 0x1
  21 #define LPO_CLK_SHIFT           8
  22 #define WDOG_CS_CLK             (LPO_CLK << LPO_CLK_SHIFT)
  23 #define WDOG_CS_EN              BIT(7)
  24 #define WDOG_CS_UPDATE          BIT(5)
  25
  26 #define WDOG_CNT        0x4
  27 #define WDOG_TOVAL      0x8
  28
  29 #define REFRESH_SEQ0    0xA602
  30 #define REFRESH_SEQ1    0xB480
  31 #define REFRESH         ((REFRESH_SEQ1 << 16) | REFRESH_SEQ0)
  32
  33 #define UNLOCK_SEQ0     0xC520
  34 #define UNLOCK_SEQ1     0xD928
  35 #define UNLOCK          ((UNLOCK_SEQ1 << 16) | UNLOCK_SEQ0)
  36
  37 #define DEFAULT_TIMEOUT 60
  38 #define MAX_TIMEOUT     128
  39 #define WDOG_CLOCK_RATE 1000
  40
  41 static bool nowayout = WATCHDOG_NOWAYOUT;
  42 module_param(nowayout, bool, 0000);
  43 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  44                  __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  45
  46 struct imx7ulp_wdt_device {
  47         struct watchdog_device wdd;
  48         void __iomem *base;
  49         struct clk *clk;
  50 };
  51
  52 static void imx7ulp_wdt_enable(struct watchdog_device *wdog, bool enable)
  53 {
  54         struct imx7ulp_wdt_device *wdt = watchdog_get_drvdata(wdog);
  55
  56         u32 val = readl(wdt->base + WDOG_CS);
  57
  58         writel(UNLOCK, wdt->base + WDOG_CNT);
  59         if (enable)
  60                 writel(val | WDOG_CS_EN, wdt->base + WDOG_CS);
  61         else
  62                 writel(val & ~WDOG_CS_EN, wdt->base + WDOG_CS);
  63 }
  64
  65 static bool imx7ulp_wdt_is_enabled(void __iomem *base)
  66 {
  67         u32 val = readl(base + WDOG_CS);
  68
  69         return val & WDOG_CS_EN;
  70 }
  71
  72 static int imx7ulp_wdt_ping(struct watchdog_device *wdog)
  73 {
  74         struct imx7ulp_wdt_device *wdt = watchdog_get_drvdata(wdog);
  75
  76         writel(REFRESH, wdt->base + WDOG_CNT);
  77
  78         return 0;
  79 }
  80
  81 static int imx7ulp_wdt_start(struct watchdog_device *wdog)
  82 {
  83
  84         imx7ulp_wdt_enable(wdog, true);
  85
  86         return 0;
  87 }
  88
  89 static int imx7ulp_wdt_stop(struct watchdog_device *wdog)
  90 {
  91         imx7ulp_wdt_enable(wdog, false);
  92
  93         return 0;
  94 }
  95
  96 static int imx7ulp_wdt_set_timeout(struct watchdog_device *wdog,
  97                                    unsigned int timeout)
  98 {
  99         struct imx7ulp_wdt_device *wdt = watchdog_get_drvdata(wdog);
 100         u32 val = WDOG_CLOCK_RATE * timeout;
 101
 102         writel(UNLOCK, wdt->base + WDOG_CNT);
 103         writel(val, wdt->base + WDOG_TOVAL);
 104
 105         wdog->timeout = timeout;
 106
 107         return 0;
 108 }
 109
 110 static int imx7ulp_wdt_restart(struct watchdog_device *wdog,
 111                                unsigned long action, void *data)
 112 {
 113         struct imx7ulp_wdt_device *wdt = watchdog_get_drvdata(wdog);
 114
 115         imx7ulp_wdt_enable(wdog, true);
 116         imx7ulp_wdt_set_timeout(&wdt->wdd, 1);
 117
 118         /* wait for wdog to fire */
 119         while (true)
 120                 ;
 121
 122         return NOTIFY_DONE;
 123 }
 124
 125 static const struct watchdog_ops imx7ulp_wdt_ops = {
 126         .owner = THIS_MODULE,
 127         .start = imx7ulp_wdt_start,
 128         .stop  = imx7ulp_wdt_stop,
 129         .ping  = imx7ulp_wdt_ping,
 130         .set_timeout = imx7ulp_wdt_set_timeout,
 131         .restart = imx7ulp_wdt_restart,
 132 };
 133
 134 static const struct watchdog_info imx7ulp_wdt_info = {
 135         .identity = "i.MX7ULP watchdog timer",
 136         .options  = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 137                     WDIOF_MAGICCLOSE,
 138 };
 139
 140 static void imx7ulp_wdt_init(void __iomem *base, unsigned int timeout)
 141 {
 142         u32 val;
 143
 144         /* unlock the wdog for reconfiguration */
 145         writel_relaxed(UNLOCK_SEQ0, base + WDOG_CNT);
 146         writel_relaxed(UNLOCK_SEQ1, base + WDOG_CNT);
 147
 148         /* set an initial timeout value in TOVAL */
 149         writel(timeout, base + WDOG_TOVAL);
 150         /* enable 32bit command sequence and reconfigure */
 151         val = WDOG_CS_CMD32EN | WDOG_CS_CLK | WDOG_CS_UPDATE;
 152         writel(val, base + WDOG_CS);
 153 }
 154
 155 static void imx7ulp_wdt_action(void *data)
 156 {
 157         clk_disable_unprepare(data);
 158 }
 159
 160 static int imx7ulp_wdt_probe(struct platform_device *pdev)
 161 {
 162         struct imx7ulp_wdt_device *imx7ulp_wdt;
 163         struct device *dev = &pdev->dev;
 164         struct watchdog_device *wdog;
 165         int ret;
 166
 167         imx7ulp_wdt = devm_kzalloc(dev, sizeof(*imx7ulp_wdt), GFP_KERNEL);
 168         if (!imx7ulp_wdt)
 169                 return -ENOMEM;
 170
 171         platform_set_drvdata(pdev, imx7ulp_wdt);
 172
 173         imx7ulp_wdt->base = devm_platform_ioremap_resource(pdev, 0);
 174         if (IS_ERR(imx7ulp_wdt->base))
 175                 return PTR_ERR(imx7ulp_wdt->base);
 176
 177         imx7ulp_wdt->clk = devm_clk_get(dev, NULL);
 178         if (IS_ERR(imx7ulp_wdt->clk)) {
 179                 dev_err(dev, "Failed to get watchdog clock\n");
 180                 return PTR_ERR(imx7ulp_wdt->clk);
 181         }
 182
 183         ret = clk_prepare_enable(imx7ulp_wdt->clk);
 184         if (ret)
 185                 return ret;
 186
 187         ret = devm_add_action_or_reset(dev, imx7ulp_wdt_action, imx7ulp_wdt->clk);
 188         if (ret)
 189                 return ret;
 190
 191         wdog = &imx7ulp_wdt->wdd;
 192         wdog->info = &imx7ulp_wdt_info;
 193         wdog->ops = &imx7ulp_wdt_ops;
 194         wdog->min_timeout = 1;
 195         wdog->max_timeout = MAX_TIMEOUT;
 196         wdog->parent = dev;
 197         wdog->timeout = DEFAULT_TIMEOUT;
 198
 199         watchdog_init_timeout(wdog, 0, dev);
 200         watchdog_stop_on_reboot(wdog);
 201         watchdog_stop_on_unregister(wdog);
 202         watchdog_set_drvdata(wdog, imx7ulp_wdt);
 203         imx7ulp_wdt_init(imx7ulp_wdt->base, wdog->timeout * WDOG_CLOCK_RATE);
 204
 205         return devm_watchdog_register_device(dev, wdog);
 206 }
 207
 208 static int __maybe_unused imx7ulp_wdt_suspend(struct device *dev)
 209 {
 210         struct imx7ulp_wdt_device *imx7ulp_wdt = dev_get_drvdata(dev);
 211
 212         if (watchdog_active(&imx7ulp_wdt->wdd))
 213                 imx7ulp_wdt_stop(&imx7ulp_wdt->wdd);
 214
 215         clk_disable_unprepare(imx7ulp_wdt->clk);
 216
 217         return 0;
 218 }
 219
 220 static int __maybe_unused imx7ulp_wdt_resume(struct device *dev)
 221 {
 222         struct imx7ulp_wdt_device *imx7ulp_wdt = dev_get_drvdata(dev);
 223         u32 timeout = imx7ulp_wdt->wdd.timeout * WDOG_CLOCK_RATE;
 224         int ret;
 225
 226         ret = clk_prepare_enable(imx7ulp_wdt->clk);
 227         if (ret)
 228                 return ret;
 229
 230         if (imx7ulp_wdt_is_enabled(imx7ulp_wdt->base))
 231                 imx7ulp_wdt_init(imx7ulp_wdt->base, timeout);
 232
 233         if (watchdog_active(&imx7ulp_wdt->wdd))
 234                 imx7ulp_wdt_start(&imx7ulp_wdt->wdd);
 235
 236         return 0;
 237 }
 238
 239 static SIMPLE_DEV_PM_OPS(imx7ulp_wdt_pm_ops, imx7ulp_wdt_suspend,
 240                          imx7ulp_wdt_resume);
 241
 242 static const struct of_device_id imx7ulp_wdt_dt_ids[] = {
 243         { .compatible = "fsl,imx7ulp-wdt", },
 244         { /* sentinel */ }
 245 };
 246 MODULE_DEVICE_TABLE(of, imx7ulp_wdt_dt_ids);
 247
 248 static struct platform_driver imx7ulp_wdt_driver = {
 249         .probe          = imx7ulp_wdt_probe,
 250         .driver         = {
 251                 .name   = "imx7ulp-wdt",
 252                 .pm     = &imx7ulp_wdt_pm_ops,
 253                 .of_match_table = imx7ulp_wdt_dt_ids,
 254         },
 255 };
 256 module_platform_driver(imx7ulp_wdt_driver);
 257
 258 MODULE_AUTHOR("Anson Huang <Anson.Huang@nxp.com>");
 259 MODULE_DESCRIPTION("Freescale i.MX7ULP watchdog driver");
 260 MODULE_LICENSE("GPL v2");