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 stih407_syscfg = {
  56         .enable_reg             = 0x204,
  57         .enable_mask            = BIT(19),
  58 };
  59
  60 static const struct of_device_id st_wdog_match[] = {
  61         {
  62                 .compatible = "st,stih407-lpc",
  63                 .data = &stih407_syscfg,
  64         },
  65         {},
  66 };
  67 MODULE_DEVICE_TABLE(of, st_wdog_match);
  68
  69 static void st_wdog_setup(struct st_wdog *st_wdog, bool enable)
  70 {
  71         /* Type of watchdog reset - 0: Cold 1: Warm */
  72         if (st_wdog->syscfg->reset_type_reg)
  73                 regmap_update_bits(st_wdog->regmap,
  74                                    st_wdog->syscfg->reset_type_reg,
  75                                    st_wdog->syscfg->reset_type_mask,
  76                                    st_wdog->warm_reset);
  77
  78         /* Mask/unmask watchdog reset */
  79         regmap_update_bits(st_wdog->regmap,
  80                            st_wdog->syscfg->enable_reg,
  81                            st_wdog->syscfg->enable_mask,
  82                            enable ? 0 : st_wdog->syscfg->enable_mask);
  83 }
  84
  85 static void st_wdog_load_timer(struct st_wdog *st_wdog, unsigned int timeout)
  86 {
  87         unsigned long clkrate = st_wdog->clkrate;
  88
  89         writel_relaxed(timeout * clkrate, st_wdog->base + LPC_LPA_LSB_OFF);
  90         writel_relaxed(1, st_wdog->base + LPC_LPA_START_OFF);
  91 }
  92
  93 static int st_wdog_start(struct watchdog_device *wdd)
  94 {
  95         struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
  96
  97         writel_relaxed(1, st_wdog->base + LPC_WDT_OFF);
  98
  99         return 0;
 100 }
 101
 102 static int st_wdog_stop(struct watchdog_device *wdd)
 103 {
 104         struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
 105
 106         writel_relaxed(0, st_wdog->base + LPC_WDT_OFF);
 107
 108         return 0;
 109 }
 110
 111 static int st_wdog_set_timeout(struct watchdog_device *wdd,
 112                                unsigned int timeout)
 113 {
 114         struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
 115
 116         wdd->timeout = timeout;
 117         st_wdog_load_timer(st_wdog, timeout);
 118
 119         return 0;
 120 }
 121
 122 static int st_wdog_keepalive(struct watchdog_device *wdd)
 123 {
 124         struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
 125
 126         st_wdog_load_timer(st_wdog, wdd->timeout);
 127
 128         return 0;
 129 }
 130
 131 static const struct watchdog_info st_wdog_info = {
 132         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 133         .identity = "ST LPC WDT",
 134 };
 135
 136 static const struct watchdog_ops st_wdog_ops = {
 137         .owner          = THIS_MODULE,
 138         .start          = st_wdog_start,
 139         .stop           = st_wdog_stop,
 140         .ping           = st_wdog_keepalive,
 141         .set_timeout    = st_wdog_set_timeout,
 142 };
 143
 144 static struct watchdog_device st_wdog_dev = {
 145         .info           = &st_wdog_info,
 146         .ops            = &st_wdog_ops,
 147 };
 148
 149 static int st_wdog_probe(struct platform_device *pdev)
 150 {
 151         const struct of_device_id *match;
 152         struct device_node *np = pdev->dev.of_node;
 153         struct st_wdog *st_wdog;
 154         struct regmap *regmap;
 155         struct resource *res;
 156         struct clk *clk;
 157         void __iomem *base;
 158         uint32_t mode;
 159         int ret;
 160
 161         ret = of_property_read_u32(np, "st,lpc-mode", &mode);
 162         if (ret) {
 163                 dev_err(&pdev->dev, "An LPC mode must be provided\n");
 164                 return -EINVAL;
 165         }
 166
 167         /* LPC can either run as a Clocksource or in RTC or WDT mode */
 168         if (mode != ST_LPC_MODE_WDT)
 169                 return -ENODEV;
 170
 171         st_wdog = devm_kzalloc(&pdev->dev, sizeof(*st_wdog), GFP_KERNEL);
 172         if (!st_wdog)
 173                 return -ENOMEM;
 174
 175         match = of_match_device(st_wdog_match, &pdev->dev);
 176         if (!match) {
 177                 dev_err(&pdev->dev, "Couldn't match device\n");
 178                 return -ENODEV;
 179         }
 180         st_wdog->syscfg = (struct st_wdog_syscfg *)match->data;
 181
 182         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 183         base = devm_ioremap_resource(&pdev->dev, res);
 184         if (IS_ERR(base))
 185                 return PTR_ERR(base);
 186
 187         regmap = syscon_regmap_lookup_by_phandle(np, "st,syscfg");
 188         if (IS_ERR(regmap)) {
 189                 dev_err(&pdev->dev, "No syscfg phandle specified\n");
 190                 return PTR_ERR(regmap);
 191         }
 192
 193         clk = devm_clk_get(&pdev->dev, NULL);
 194         if (IS_ERR(clk)) {
 195                 dev_err(&pdev->dev, "Unable to request clock\n");
 196                 return PTR_ERR(clk);
 197         }
 198
 199         st_wdog->dev            = &pdev->dev;
 200         st_wdog->base           = base;
 201         st_wdog->clk            = clk;
 202         st_wdog->regmap         = regmap;
 203         st_wdog->warm_reset     = of_property_read_bool(np, "st,warm_reset");
 204         st_wdog->clkrate        = clk_get_rate(st_wdog->clk);
 205
 206         if (!st_wdog->clkrate) {
 207                 dev_err(&pdev->dev, "Unable to fetch clock rate\n");
 208                 return -EINVAL;
 209         }
 210         st_wdog_dev.max_timeout = 0xFFFFFFFF / st_wdog->clkrate;
 211         st_wdog_dev.parent = &pdev->dev;
 212
 213         ret = clk_prepare_enable(clk);
 214         if (ret) {
 215                 dev_err(&pdev->dev, "Unable to enable clock\n");
 216                 return ret;
 217         }
 218
 219         watchdog_set_drvdata(&st_wdog_dev, st_wdog);
 220         watchdog_set_nowayout(&st_wdog_dev, WATCHDOG_NOWAYOUT);
 221
 222         /* Init Watchdog timeout with value in DT */
 223         ret = watchdog_init_timeout(&st_wdog_dev, 0, &pdev->dev);
 224         if (ret) {
 225                 dev_err(&pdev->dev, "Unable to initialise watchdog timeout\n");
 226                 clk_disable_unprepare(clk);
 227                 return ret;
 228         }
 229
 230         ret = watchdog_register_device(&st_wdog_dev);
 231         if (ret) {
 232                 dev_err(&pdev->dev, "Unable to register watchdog\n");
 233                 clk_disable_unprepare(clk);
 234                 return ret;
 235         }
 236
 237         st_wdog_setup(st_wdog, true);
 238
 239         dev_info(&pdev->dev, "LPC Watchdog driver registered, reset type is %s",
 240                  st_wdog->warm_reset ? "warm" : "cold");
 241
 242         return ret;
 243 }
 244
 245 static int st_wdog_remove(struct platform_device *pdev)
 246 {
 247         struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
 248
 249         st_wdog_setup(st_wdog, false);
 250         watchdog_unregister_device(&st_wdog_dev);
 251         clk_disable_unprepare(st_wdog->clk);
 252
 253         return 0;
 254 }
 255
 256 #ifdef CONFIG_PM_SLEEP
 257 static int st_wdog_suspend(struct device *dev)
 258 {
 259         struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
 260
 261         if (watchdog_active(&st_wdog_dev))
 262                 st_wdog_stop(&st_wdog_dev);
 263
 264         st_wdog_setup(st_wdog, false);
 265
 266         clk_disable(st_wdog->clk);
 267
 268         return 0;
 269 }
 270
 271 static int st_wdog_resume(struct device *dev)
 272 {
 273         struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
 274         int ret;
 275
 276         ret = clk_enable(st_wdog->clk);
 277         if (ret) {
 278                 dev_err(dev, "Unable to re-enable clock\n");
 279                 watchdog_unregister_device(&st_wdog_dev);
 280                 clk_unprepare(st_wdog->clk);
 281                 return ret;
 282         }
 283
 284         st_wdog_setup(st_wdog, true);
 285
 286         if (watchdog_active(&st_wdog_dev)) {
 287                 st_wdog_load_timer(st_wdog, st_wdog_dev.timeout);
 288                 st_wdog_start(&st_wdog_dev);
 289         }
 290
 291         return 0;
 292 }
 293 #endif
 294
 295 static SIMPLE_DEV_PM_OPS(st_wdog_pm_ops,
 296                          st_wdog_suspend,
 297                          st_wdog_resume);
 298
 299 static struct platform_driver st_wdog_driver = {
 300         .driver = {
 301                 .name = "st-lpc-wdt",
 302                 .pm = &st_wdog_pm_ops,
 303                 .of_match_table = st_wdog_match,
 304         },
 305         .probe = st_wdog_probe,
 306         .remove = st_wdog_remove,
 307 };
 308 module_platform_driver(st_wdog_driver);
 309
 310 MODULE_AUTHOR("David Paris <david.paris@st.com>");
 311 MODULE_DESCRIPTION("ST LPC Watchdog Driver");
 312 MODULE_LICENSE("GPL");