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/platform_device.h>
  19 #include <linux/regmap.h>
  20 #include <linux/watchdog.h>
  21
  22 #include <dt-bindings/mfd/st-lpc.h>
  23
  24 /* Low Power Alarm */
  25 #define LPC_LPA_LSB_OFF                 0x410
  26 #define LPC_LPA_START_OFF               0x418
  27
  28 /* LPC as WDT */
  29 #define LPC_WDT_OFF                     0x510
  30
  31 static struct watchdog_device st_wdog_dev;
  32
  33 struct st_wdog_syscfg {
  34         unsigned int reset_type_reg;
  35         unsigned int reset_type_mask;
  36         unsigned int enable_reg;
  37         unsigned int enable_mask;
  38 };
  39
  40 struct st_wdog {
  41         void __iomem *base;
  42         struct device *dev;
  43         struct regmap *regmap;
  44         const struct st_wdog_syscfg *syscfg;
  45         struct clk *clk;
  46         unsigned long clkrate;
  47         bool warm_reset;
  48 };
  49
  50 static struct st_wdog_syscfg stih407_syscfg = {
  51         .enable_reg             = 0x204,
  52         .enable_mask            = BIT(19),
  53 };
  54
  55 static const struct of_device_id st_wdog_match[] = {
  56         {
  57                 .compatible = "st,stih407-lpc",
  58                 .data = &stih407_syscfg,
  59         },
  60         {},
  61 };
  62 MODULE_DEVICE_TABLE(of, st_wdog_match);
  63
  64 static void st_wdog_setup(struct st_wdog *st_wdog, bool enable)
  65 {
  66         /* Type of watchdog reset - 0: Cold 1: Warm */
  67         if (st_wdog->syscfg->reset_type_reg)
  68                 regmap_update_bits(st_wdog->regmap,
  69                                    st_wdog->syscfg->reset_type_reg,
  70                                    st_wdog->syscfg->reset_type_mask,
  71                                    st_wdog->warm_reset);
  72
  73         /* Mask/unmask watchdog reset */
  74         regmap_update_bits(st_wdog->regmap,
  75                            st_wdog->syscfg->enable_reg,
  76                            st_wdog->syscfg->enable_mask,
  77                            enable ? 0 : st_wdog->syscfg->enable_mask);
  78 }
  79
  80 static void st_wdog_load_timer(struct st_wdog *st_wdog, unsigned int timeout)
  81 {
  82         unsigned long clkrate = st_wdog->clkrate;
  83
  84         writel_relaxed(timeout * clkrate, st_wdog->base + LPC_LPA_LSB_OFF);
  85         writel_relaxed(1, st_wdog->base + LPC_LPA_START_OFF);
  86 }
  87
  88 static int st_wdog_start(struct watchdog_device *wdd)
  89 {
  90         struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
  91
  92         writel_relaxed(1, st_wdog->base + LPC_WDT_OFF);
  93
  94         return 0;
  95 }
  96
  97 static int st_wdog_stop(struct watchdog_device *wdd)
  98 {
  99         struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
 100
 101         writel_relaxed(0, st_wdog->base + LPC_WDT_OFF);
 102
 103         return 0;
 104 }
 105
 106 static int st_wdog_set_timeout(struct watchdog_device *wdd,
 107                                unsigned int timeout)
 108 {
 109         struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
 110
 111         wdd->timeout = timeout;
 112         st_wdog_load_timer(st_wdog, timeout);
 113
 114         return 0;
 115 }
 116
 117 static int st_wdog_keepalive(struct watchdog_device *wdd)
 118 {
 119         struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
 120
 121         st_wdog_load_timer(st_wdog, wdd->timeout);
 122
 123         return 0;
 124 }
 125
 126 static const struct watchdog_info st_wdog_info = {
 127         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 128         .identity = "ST LPC WDT",
 129 };
 130
 131 static const struct watchdog_ops st_wdog_ops = {
 132         .owner          = THIS_MODULE,
 133         .start          = st_wdog_start,
 134         .stop           = st_wdog_stop,
 135         .ping           = st_wdog_keepalive,
 136         .set_timeout    = st_wdog_set_timeout,
 137 };
 138
 139 static struct watchdog_device st_wdog_dev = {
 140         .info           = &st_wdog_info,
 141         .ops            = &st_wdog_ops,
 142 };
 143
 144 static void st_clk_disable_unprepare(void *data)
 145 {
 146         clk_disable_unprepare(data);
 147 }
 148
 149 static int st_wdog_probe(struct platform_device *pdev)
 150 {
 151         struct device *dev = &pdev->dev;
 152         struct device_node *np = dev->of_node;
 153         struct st_wdog *st_wdog;
 154         struct regmap *regmap;
 155         struct clk *clk;
 156         void __iomem *base;
 157         uint32_t mode;
 158         int ret;
 159
 160         ret = of_property_read_u32(np, "st,lpc-mode", &mode);
 161         if (ret) {
 162                 dev_err(dev, "An LPC mode must be provided\n");
 163                 return -EINVAL;
 164         }
 165
 166         /* LPC can either run as a Clocksource or in RTC or WDT mode */
 167         if (mode != ST_LPC_MODE_WDT)
 168                 return -ENODEV;
 169
 170         st_wdog = devm_kzalloc(dev, sizeof(*st_wdog), GFP_KERNEL);
 171         if (!st_wdog)
 172                 return -ENOMEM;
 173
 174         st_wdog->syscfg = (struct st_wdog_syscfg *)device_get_match_data(dev);
 175
 176         base = devm_platform_ioremap_resource(pdev, 0);
 177         if (IS_ERR(base))
 178                 return PTR_ERR(base);
 179
 180         regmap = syscon_regmap_lookup_by_phandle(np, "st,syscfg");
 181         if (IS_ERR(regmap)) {
 182                 dev_err(dev, "No syscfg phandle specified\n");
 183                 return PTR_ERR(regmap);
 184         }
 185
 186         clk = devm_clk_get(dev, NULL);
 187         if (IS_ERR(clk)) {
 188                 dev_err(dev, "Unable to request clock\n");
 189                 return PTR_ERR(clk);
 190         }
 191
 192         st_wdog->dev            = dev;
 193         st_wdog->base           = base;
 194         st_wdog->clk            = clk;
 195         st_wdog->regmap         = regmap;
 196         st_wdog->warm_reset     = of_property_read_bool(np, "st,warm_reset");
 197         st_wdog->clkrate        = clk_get_rate(st_wdog->clk);
 198
 199         if (!st_wdog->clkrate) {
 200                 dev_err(dev, "Unable to fetch clock rate\n");
 201                 return -EINVAL;
 202         }
 203         st_wdog_dev.max_timeout = 0xFFFFFFFF / st_wdog->clkrate;
 204         st_wdog_dev.parent = dev;
 205
 206         ret = clk_prepare_enable(clk);
 207         if (ret) {
 208                 dev_err(dev, "Unable to enable clock\n");
 209                 return ret;
 210         }
 211         ret = devm_add_action_or_reset(dev, st_clk_disable_unprepare, clk);
 212         if (ret)
 213                 return ret;
 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, dev);
 220         if (ret)
 221                 return ret;
 222
 223         ret = devm_watchdog_register_device(dev, &st_wdog_dev);
 224         if (ret)
 225                 return ret;
 226
 227         st_wdog_setup(st_wdog, true);
 228
 229         dev_info(dev, "LPC Watchdog driver registered, reset type is %s",
 230                  st_wdog->warm_reset ? "warm" : "cold");
 231
 232         return ret;
 233 }
 234
 235 static void st_wdog_remove(struct platform_device *pdev)
 236 {
 237         struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
 238
 239         st_wdog_setup(st_wdog, false);
 240 }
 241
 242 static int st_wdog_suspend(struct device *dev)
 243 {
 244         struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
 245
 246         if (watchdog_active(&st_wdog_dev))
 247                 st_wdog_stop(&st_wdog_dev);
 248
 249         st_wdog_setup(st_wdog, false);
 250
 251         clk_disable(st_wdog->clk);
 252
 253         return 0;
 254 }
 255
 256 static int st_wdog_resume(struct device *dev)
 257 {
 258         struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
 259         int ret;
 260
 261         ret = clk_enable(st_wdog->clk);
 262         if (ret) {
 263                 dev_err(dev, "Unable to re-enable clock\n");
 264                 watchdog_unregister_device(&st_wdog_dev);
 265                 clk_unprepare(st_wdog->clk);
 266                 return ret;
 267         }
 268
 269         st_wdog_setup(st_wdog, true);
 270
 271         if (watchdog_active(&st_wdog_dev)) {
 272                 st_wdog_load_timer(st_wdog, st_wdog_dev.timeout);
 273                 st_wdog_start(&st_wdog_dev);
 274         }
 275
 276         return 0;
 277 }
 278
 279 static DEFINE_SIMPLE_DEV_PM_OPS(st_wdog_pm_ops,
 280                                 st_wdog_suspend, st_wdog_resume);
 281
 282 static struct platform_driver st_wdog_driver = {
 283         .driver = {
 284                 .name = "st-lpc-wdt",
 285                 .pm = pm_sleep_ptr(&st_wdog_pm_ops),
 286                 .of_match_table = st_wdog_match,
 287         },
 288         .probe = st_wdog_probe,
 289         .remove_new = st_wdog_remove,
 290 };
 291 module_platform_driver(st_wdog_driver);
 292
 293 MODULE_AUTHOR("David Paris <david.paris@st.com>");
 294 MODULE_DESCRIPTION("ST LPC Watchdog Driver");
 295 MODULE_LICENSE("GPL");