drivers/watchdog/st_lpc_wdt.c

   1 /*
   2  * ST's LPC Watchdog
   3  *
   4  * Copyright (C) 2014 STMicroelectronics -- All Rights Reserved
   5  *
   6  * Author: David Paris <david.paris@st.com> for STMicroelectronics
   7  *         Lee Jones <lee.jones@linaro.org> for STMicroelectronics
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public Licence
  11  * as published by the Free Software Foundation; either version
  12  * 2 of the Licence, or (at your option) any later version.
  13  */
  14
  15 #include <linux/clk.h>
  16 #include <linux/init.h>
  17 #include <linux/io.h>
  18 #include <linux/kernel.h>
  19 #include <linux/mfd/syscon.h>
  20 #include <linux/module.h>
  21 #include <linux/of.h>
  22 #include <linux/of_platform.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/regmap.h>
  25 #include <linux/watchdog.h>
  26
  27 #include <dt-bindings/mfd/st-lpc.h>
  28
  29 /* Low Power Alarm */
  30 #define LPC_LPA_LSB_OFF                 0x410
  31 #define LPC_LPA_START_OFF               0x418
  32
  33 /* LPC as WDT */
  34 #define LPC_WDT_OFF                     0x510
  35
  36 static struct watchdog_device st_wdog_dev;
  37
  38 struct st_wdog_syscfg {
  39         unsigned int reset_type_reg;
  40         unsigned int reset_type_mask;
  41         unsigned int enable_reg;
  42         unsigned int enable_mask;
  43 };
  44
  45 struct st_wdog {
  46         void __iomem *base;
  47         struct device *dev;
  48         struct regmap *regmap;
  49         struct st_wdog_syscfg *syscfg;
  50         struct clk *clk;
  51         unsigned long clkrate;
  52         bool warm_reset;
  53 };
  54
  55 static struct st_wdog_syscfg stid127_syscfg = {
  56         .reset_type_reg         = 0x004,
  57         .reset_type_mask        = BIT(2),
  58         .enable_reg             = 0x000,
  59         .enable_mask            = BIT(2),
  60 };
  61
  62 static struct st_wdog_syscfg stih415_syscfg = {
  63         .reset_type_reg         = 0x0B8,
  64         .reset_type_mask        = BIT(6),
  65         .enable_reg             = 0x0B4,
  66         .enable_mask            = BIT(7),
  67 };
  68
  69 static struct st_wdog_syscfg stih416_syscfg = {
  70         .reset_type_reg         = 0x88C,
  71         .reset_type_mask        = BIT(6),
  72         .enable_reg             = 0x888,
  73         .enable_mask            = BIT(7),
  74 };
  75
  76 static struct st_wdog_syscfg stih407_syscfg = {
  77         .enable_reg             = 0x204,
  78         .enable_mask            = BIT(19),
  79 };
  80
  81 static const struct of_device_id st_wdog_match[] = {
  82         {
  83                 .compatible = "st,stih407-lpc",
  84                 .data = &stih407_syscfg,
  85         },
  86         {
  87                 .compatible = "st,stih416-lpc",
  88                 .data = &stih416_syscfg,
  89         },
  90         {
  91                 .compatible = "st,stih415-lpc",
  92                 .data = &stih415_syscfg,
  93         },
  94         {
  95                 .compatible = "st,stid127-lpc",
  96                 .data = &stid127_syscfg,
  97         },
  98         {},
  99 };
 100 MODULE_DEVICE_TABLE(of, st_wdog_match);
 101
 102 static void st_wdog_setup(struct st_wdog *st_wdog, bool enable)
 103 {
 104         /* Type of watchdog reset - 0: Cold 1: Warm */
 105         if (st_wdog->syscfg->reset_type_reg)
 106                 regmap_update_bits(st_wdog->regmap,
 107                                    st_wdog->syscfg->reset_type_reg,
 108                                    st_wdog->syscfg->reset_type_mask,
 109                                    st_wdog->warm_reset);
 110
 111         /* Mask/unmask watchdog reset */
 112         regmap_update_bits(st_wdog->regmap,
 113                            st_wdog->syscfg->enable_reg,
 114                            st_wdog->syscfg->enable_mask,
 115                            enable ? 0 : st_wdog->syscfg->enable_mask);
 116 }
 117
 118 static void st_wdog_load_timer(struct st_wdog *st_wdog, unsigned int timeout)
 119 {
 120         unsigned long clkrate = st_wdog->clkrate;
 121
 122         writel_relaxed(timeout * clkrate, st_wdog->base + LPC_LPA_LSB_OFF);
 123         writel_relaxed(1, st_wdog->base + LPC_LPA_START_OFF);
 124 }
 125
 126 static int st_wdog_start(struct watchdog_device *wdd)
 127 {
 128         struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
 129
 130         writel_relaxed(1, st_wdog->base + LPC_WDT_OFF);
 131
 132         return 0;
 133 }
 134
 135 static int st_wdog_stop(struct watchdog_device *wdd)
 136 {
 137         struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
 138
 139         writel_relaxed(0, st_wdog->base + LPC_WDT_OFF);
 140
 141         return 0;
 142 }
 143
 144 static int st_wdog_set_timeout(struct watchdog_device *wdd,
 145                                unsigned int timeout)
 146 {
 147         struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
 148
 149         wdd->timeout = timeout;
 150         st_wdog_load_timer(st_wdog, timeout);
 151
 152         return 0;
 153 }
 154
 155 static int st_wdog_keepalive(struct watchdog_device *wdd)
 156 {
 157         struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
 158
 159         st_wdog_load_timer(st_wdog, wdd->timeout);
 160
 161         return 0;
 162 }
 163
 164 static const struct watchdog_info st_wdog_info = {
 165         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 166         .identity = "ST LPC WDT",
 167 };
 168
 169 static const struct watchdog_ops st_wdog_ops = {
 170         .owner          = THIS_MODULE,
 171         .start          = st_wdog_start,
 172         .stop           = st_wdog_stop,
 173         .ping           = st_wdog_keepalive,
 174         .set_timeout    = st_wdog_set_timeout,
 175 };
 176
 177 static struct watchdog_device st_wdog_dev = {
 178         .info           = &st_wdog_info,
 179         .ops            = &st_wdog_ops,
 180 };
 181
 182 static int st_wdog_probe(struct platform_device *pdev)
 183 {
 184         const struct of_device_id *match;
 185         struct device_node *np = pdev->dev.of_node;
 186         struct st_wdog *st_wdog;
 187         struct regmap *regmap;
 188         struct resource *res;
 189         struct clk *clk;
 190         void __iomem *base;
 191         uint32_t mode;
 192         int ret;
 193
 194         ret = of_property_read_u32(np, "st,lpc-mode", &mode);
 195         if (ret) {
 196                 dev_err(&pdev->dev, "An LPC mode must be provided\n");
 197                 return -EINVAL;
 198         }
 199
 200         /* LPC can either run as a Clocksource or in RTC or WDT mode */
 201         if (mode != ST_LPC_MODE_WDT)
 202                 return -ENODEV;
 203
 204         st_wdog = devm_kzalloc(&pdev->dev, sizeof(*st_wdog), GFP_KERNEL);
 205         if (!st_wdog)
 206                 return -ENOMEM;
 207
 208         match = of_match_device(st_wdog_match, &pdev->dev);
 209         if (!match) {
 210                 dev_err(&pdev->dev, "Couldn't match device\n");
 211                 return -ENODEV;
 212         }
 213         st_wdog->syscfg = (struct st_wdog_syscfg *)match->data;
 214
 215         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 216         base = devm_ioremap_resource(&pdev->dev, res);
 217         if (IS_ERR(base))
 218                 return PTR_ERR(base);
 219
 220         regmap = syscon_regmap_lookup_by_phandle(np, "st,syscfg");
 221         if (IS_ERR(regmap)) {
 222                 dev_err(&pdev->dev, "No syscfg phandle specified\n");
 223                 return PTR_ERR(regmap);
 224         }
 225
 226         clk = devm_clk_get(&pdev->dev, NULL);
 227         if (IS_ERR(clk)) {
 228                 dev_err(&pdev->dev, "Unable to request clock\n");
 229                 return PTR_ERR(clk);
 230         }
 231
 232         st_wdog->dev            = &pdev->dev;
 233         st_wdog->base           = base;
 234         st_wdog->clk            = clk;
 235         st_wdog->regmap         = regmap;
 236         st_wdog->warm_reset     = of_property_read_bool(np, "st,warm_reset");
 237         st_wdog->clkrate        = clk_get_rate(st_wdog->clk);
 238
 239         if (!st_wdog->clkrate) {
 240                 dev_err(&pdev->dev, "Unable to fetch clock rate\n");
 241                 return -EINVAL;
 242         }
 243         st_wdog_dev.max_timeout = 0xFFFFFFFF / st_wdog->clkrate;
 244         st_wdog_dev.parent = &pdev->dev;
 245
 246         ret = clk_prepare_enable(clk);
 247         if (ret) {
 248                 dev_err(&pdev->dev, "Unable to enable clock\n");
 249                 return ret;
 250         }
 251
 252         watchdog_set_drvdata(&st_wdog_dev, st_wdog);
 253         watchdog_set_nowayout(&st_wdog_dev, WATCHDOG_NOWAYOUT);
 254
 255         /* Init Watchdog timeout with value in DT */
 256         ret = watchdog_init_timeout(&st_wdog_dev, 0, &pdev->dev);
 257         if (ret) {
 258                 dev_err(&pdev->dev, "Unable to initialise watchdog timeout\n");
 259                 clk_disable_unprepare(clk);
 260                 return ret;
 261         }
 262
 263         ret = watchdog_register_device(&st_wdog_dev);
 264         if (ret) {
 265                 dev_err(&pdev->dev, "Unable to register watchdog\n");
 266                 clk_disable_unprepare(clk);
 267                 return ret;
 268         }
 269
 270         st_wdog_setup(st_wdog, true);
 271
 272         dev_info(&pdev->dev, "LPC Watchdog driver registered, reset type is %s",
 273                  st_wdog->warm_reset ? "warm" : "cold");
 274
 275         return ret;
 276 }
 277
 278 static int st_wdog_remove(struct platform_device *pdev)
 279 {
 280         struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
 281
 282         st_wdog_setup(st_wdog, false);
 283         watchdog_unregister_device(&st_wdog_dev);
 284         clk_disable_unprepare(st_wdog->clk);
 285
 286         return 0;
 287 }
 288
 289 #ifdef CONFIG_PM_SLEEP
 290 static int st_wdog_suspend(struct device *dev)
 291 {
 292         struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
 293
 294         if (watchdog_active(&st_wdog_dev))
 295                 st_wdog_stop(&st_wdog_dev);
 296
 297         st_wdog_setup(st_wdog, false);
 298
 299         clk_disable(st_wdog->clk);
 300
 301         return 0;
 302 }
 303
 304 static int st_wdog_resume(struct device *dev)
 305 {
 306         struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
 307         int ret;
 308
 309         ret = clk_enable(st_wdog->clk);
 310         if (ret) {
 311                 dev_err(dev, "Unable to re-enable clock\n");
 312                 watchdog_unregister_device(&st_wdog_dev);
 313                 clk_unprepare(st_wdog->clk);
 314                 return ret;
 315         }
 316
 317         st_wdog_setup(st_wdog, true);
 318
 319         if (watchdog_active(&st_wdog_dev)) {
 320                 st_wdog_load_timer(st_wdog, st_wdog_dev.timeout);
 321                 st_wdog_start(&st_wdog_dev);
 322         }
 323
 324         return 0;
 325 }
 326 #endif
 327
 328 static SIMPLE_DEV_PM_OPS(st_wdog_pm_ops,
 329                          st_wdog_suspend,
 330                          st_wdog_resume);
 331
 332 static struct platform_driver st_wdog_driver = {
 333         .driver = {
 334                 .name = "st-lpc-wdt",
 335                 .pm = &st_wdog_pm_ops,
 336                 .of_match_table = st_wdog_match,
 337         },
 338         .probe = st_wdog_probe,
 339         .remove = st_wdog_remove,
 340 };
 341 module_platform_driver(st_wdog_driver);
 342
 343 MODULE_AUTHOR("David Paris <david.paris@st.com>");
 344 MODULE_DESCRIPTION("ST LPC Watchdog Driver");
 345 MODULE_LICENSE("GPL");