drivers/watchdog/st_lpc_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * ST's LPC Watchdog
   4  *
   5  * Copyright (C) 2014 STMicroelectronics -- All Rights Reserved
   6  *
   7  * Author: David Paris <david.paris@st.com> for STMicroelectronics
   8  *         Lee Jones <lee.jones@linaro.org> for STMicroelectronics
   9  */
  10
  11 #include <linux/clk.h>
  12 #include <linux/init.h>
  13 #include <linux/io.h>
  14 #include <linux/kernel.h>
  15 #include <linux/mfd/syscon.h>
  16 #include <linux/module.h>
  17 #include <linux/of.h>
  18 #include <linux/of_platform.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/regmap.h>
  21 #include <linux/watchdog.h>
  22
  23 #include <dt-bindings/mfd/st-lpc.h>
  24
  25 /* Low Power Alarm */
  26 #define LPC_LPA_LSB_OFF                 0x410
  27 #define LPC_LPA_START_OFF               0x418
  28
  29 /* LPC as WDT */
  30 #define LPC_WDT_OFF                     0x510
  31
  32 static struct watchdog_device st_wdog_dev;
  33
  34 struct st_wdog_syscfg {
  35         unsigned int reset_type_reg;
  36         unsigned int reset_type_mask;
  37         unsigned int enable_reg;
  38         unsigned int enable_mask;
  39 };
  40
  41 struct st_wdog {
  42         void __iomem *base;
  43         struct device *dev;
  44         struct regmap *regmap;
  45         struct st_wdog_syscfg *syscfg;
  46         struct clk *clk;
  47         unsigned long clkrate;
  48         bool warm_reset;
  49 };
  50
  51 static struct st_wdog_syscfg stih407_syscfg = {
  52         .enable_reg             = 0x204,
  53         .enable_mask            = BIT(19),
  54 };
  55
  56 static const struct of_device_id st_wdog_match[] = {
  57         {
  58                 .compatible = "st,stih407-lpc",
  59                 .data = &stih407_syscfg,
  60         },
  61         {},
  62 };
  63 MODULE_DEVICE_TABLE(of, st_wdog_match);
  64
  65 static void st_wdog_setup(struct st_wdog *st_wdog, bool enable)
  66 {
  67         /* Type of watchdog reset - 0: Cold 1: Warm */
  68         if (st_wdog->syscfg->reset_type_reg)
  69                 regmap_update_bits(st_wdog->regmap,
  70                                    st_wdog->syscfg->reset_type_reg,
  71                                    st_wdog->syscfg->reset_type_mask,
  72                                    st_wdog->warm_reset);
  73
  74         /* Mask/unmask watchdog reset */
  75         regmap_update_bits(st_wdog->regmap,
  76                            st_wdog->syscfg->enable_reg,
  77                            st_wdog->syscfg->enable_mask,
  78                            enable ? 0 : st_wdog->syscfg->enable_mask);
  79 }
  80
  81 static void st_wdog_load_timer(struct st_wdog *st_wdog, unsigned int timeout)
  82 {
  83         unsigned long clkrate = st_wdog->clkrate;
  84
  85         writel_relaxed(timeout * clkrate, st_wdog->base + LPC_LPA_LSB_OFF);
  86         writel_relaxed(1, st_wdog->base + LPC_LPA_START_OFF);
  87 }
  88
  89 static int st_wdog_start(struct watchdog_device *wdd)
  90 {
  91         struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
  92
  93         writel_relaxed(1, st_wdog->base + LPC_WDT_OFF);
  94
  95         return 0;
  96 }
  97
  98 static int st_wdog_stop(struct watchdog_device *wdd)
  99 {
 100         struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
 101
 102         writel_relaxed(0, st_wdog->base + LPC_WDT_OFF);
 103
 104         return 0;
 105 }
 106
 107 static int st_wdog_set_timeout(struct watchdog_device *wdd,
 108                                unsigned int timeout)
 109 {
 110         struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
 111
 112         wdd->timeout = timeout;
 113         st_wdog_load_timer(st_wdog, timeout);
 114
 115         return 0;
 116 }
 117
 118 static int st_wdog_keepalive(struct watchdog_device *wdd)
 119 {
 120         struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
 121
 122         st_wdog_load_timer(st_wdog, wdd->timeout);
 123
 124         return 0;
 125 }
 126
 127 static const struct watchdog_info st_wdog_info = {
 128         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 129         .identity = "ST LPC WDT",
 130 };
 131
 132 static const struct watchdog_ops st_wdog_ops = {
 133         .owner          = THIS_MODULE,
 134         .start          = st_wdog_start,
 135         .stop           = st_wdog_stop,
 136         .ping           = st_wdog_keepalive,
 137         .set_timeout    = st_wdog_set_timeout,
 138 };
 139
 140 static struct watchdog_device st_wdog_dev = {
 141         .info           = &st_wdog_info,
 142         .ops            = &st_wdog_ops,
 143 };
 144
 145 static int st_wdog_probe(struct platform_device *pdev)
 146 {
 147         const struct of_device_id *match;
 148         struct device_node *np = pdev->dev.of_node;
 149         struct st_wdog *st_wdog;
 150         struct regmap *regmap;
 151         struct resource *res;
 152         struct clk *clk;
 153         void __iomem *base;
 154         uint32_t mode;
 155         int ret;
 156
 157         ret = of_property_read_u32(np, "st,lpc-mode", &mode);
 158         if (ret) {
 159                 dev_err(&pdev->dev, "An LPC mode must be provided\n");
 160                 return -EINVAL;
 161         }
 162
 163         /* LPC can either run as a Clocksource or in RTC or WDT mode */
 164         if (mode != ST_LPC_MODE_WDT)
 165                 return -ENODEV;
 166
 167         st_wdog = devm_kzalloc(&pdev->dev, sizeof(*st_wdog), GFP_KERNEL);
 168         if (!st_wdog)
 169                 return -ENOMEM;
 170
 171         match = of_match_device(st_wdog_match, &pdev->dev);
 172         if (!match) {
 173                 dev_err(&pdev->dev, "Couldn't match device\n");
 174                 return -ENODEV;
 175         }
 176         st_wdog->syscfg = (struct st_wdog_syscfg *)match->data;
 177
 178         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 179         base = devm_ioremap_resource(&pdev->dev, res);
 180         if (IS_ERR(base))
 181                 return PTR_ERR(base);
 182
 183         regmap = syscon_regmap_lookup_by_phandle(np, "st,syscfg");
 184         if (IS_ERR(regmap)) {
 185                 dev_err(&pdev->dev, "No syscfg phandle specified\n");
 186                 return PTR_ERR(regmap);
 187         }
 188
 189         clk = devm_clk_get(&pdev->dev, NULL);
 190         if (IS_ERR(clk)) {
 191                 dev_err(&pdev->dev, "Unable to request clock\n");
 192                 return PTR_ERR(clk);
 193         }
 194
 195         st_wdog->dev            = &pdev->dev;
 196         st_wdog->base           = base;
 197         st_wdog->clk            = clk;
 198         st_wdog->regmap         = regmap;
 199         st_wdog->warm_reset     = of_property_read_bool(np, "st,warm_reset");
 200         st_wdog->clkrate        = clk_get_rate(st_wdog->clk);
 201
 202         if (!st_wdog->clkrate) {
 203                 dev_err(&pdev->dev, "Unable to fetch clock rate\n");
 204                 return -EINVAL;
 205         }
 206         st_wdog_dev.max_timeout = 0xFFFFFFFF / st_wdog->clkrate;
 207         st_wdog_dev.parent = &pdev->dev;
 208
 209         ret = clk_prepare_enable(clk);
 210         if (ret) {
 211                 dev_err(&pdev->dev, "Unable to enable clock\n");
 212                 return ret;
 213         }
 214
 215         watchdog_set_drvdata(&st_wdog_dev, st_wdog);
 216         watchdog_set_nowayout(&st_wdog_dev, WATCHDOG_NOWAYOUT);
 217
 218         /* Init Watchdog timeout with value in DT */
 219         ret = watchdog_init_timeout(&st_wdog_dev, 0, &pdev->dev);
 220         if (ret) {
 221                 dev_err(&pdev->dev, "Unable to initialise watchdog timeout\n");
 222                 clk_disable_unprepare(clk);
 223                 return ret;
 224         }
 225
 226         ret = watchdog_register_device(&st_wdog_dev);
 227         if (ret) {
 228                 dev_err(&pdev->dev, "Unable to register watchdog\n");
 229                 clk_disable_unprepare(clk);
 230                 return ret;
 231         }
 232
 233         st_wdog_setup(st_wdog, true);
 234
 235         dev_info(&pdev->dev, "LPC Watchdog driver registered, reset type is %s",
 236                  st_wdog->warm_reset ? "warm" : "cold");
 237
 238         return ret;
 239 }
 240
 241 static int st_wdog_remove(struct platform_device *pdev)
 242 {
 243         struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
 244
 245         st_wdog_setup(st_wdog, false);
 246         watchdog_unregister_device(&st_wdog_dev);
 247         clk_disable_unprepare(st_wdog->clk);
 248
 249         return 0;
 250 }
 251
 252 #ifdef CONFIG_PM_SLEEP
 253 static int st_wdog_suspend(struct device *dev)
 254 {
 255         struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
 256
 257         if (watchdog_active(&st_wdog_dev))
 258                 st_wdog_stop(&st_wdog_dev);
 259
 260         st_wdog_setup(st_wdog, false);
 261
 262         clk_disable(st_wdog->clk);
 263
 264         return 0;
 265 }
 266
 267 static int st_wdog_resume(struct device *dev)
 268 {
 269         struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
 270         int ret;
 271
 272         ret = clk_enable(st_wdog->clk);
 273         if (ret) {
 274                 dev_err(dev, "Unable to re-enable clock\n");
 275                 watchdog_unregister_device(&st_wdog_dev);
 276                 clk_unprepare(st_wdog->clk);
 277                 return ret;
 278         }
 279
 280         st_wdog_setup(st_wdog, true);
 281
 282         if (watchdog_active(&st_wdog_dev)) {
 283                 st_wdog_load_timer(st_wdog, st_wdog_dev.timeout);
 284                 st_wdog_start(&st_wdog_dev);
 285         }
 286
 287         return 0;
 288 }
 289 #endif
 290
 291 static SIMPLE_DEV_PM_OPS(st_wdog_pm_ops,
 292                          st_wdog_suspend,
 293                          st_wdog_resume);
 294
 295 static struct platform_driver st_wdog_driver = {
 296         .driver = {
 297                 .name = "st-lpc-wdt",
 298                 .pm = &st_wdog_pm_ops,
 299                 .of_match_table = st_wdog_match,
 300         },
 301         .probe = st_wdog_probe,
 302         .remove = st_wdog_remove,
 303 };
 304 module_platform_driver(st_wdog_driver);
 305
 306 MODULE_AUTHOR("David Paris <david.paris@st.com>");
 307 MODULE_DESCRIPTION("ST LPC Watchdog Driver");
 308 MODULE_LICENSE("GPL");