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 void st_clk_disable_unprepare(void *data)
 146 {
 147         clk_disable_unprepare(data);
 148 }
 149
 150 static int st_wdog_probe(struct platform_device *pdev)
 151 {
 152         struct device *dev = &pdev->dev;
 153         const struct of_device_id *match;
 154         struct device_node *np = dev->of_node;
 155         struct st_wdog *st_wdog;
 156         struct regmap *regmap;
 157         struct clk *clk;
 158         void __iomem *base;
 159         uint32_t mode;
 160         int ret;
 161
 162         ret = of_property_read_u32(np, "st,lpc-mode", &mode);
 163         if (ret) {
 164                 dev_err(dev, "An LPC mode must be provided\n");
 165                 return -EINVAL;
 166         }
 167
 168         /* LPC can either run as a Clocksource or in RTC or WDT mode */
 169         if (mode != ST_LPC_MODE_WDT)
 170                 return -ENODEV;
 171
 172         st_wdog = devm_kzalloc(dev, sizeof(*st_wdog), GFP_KERNEL);
 173         if (!st_wdog)
 174                 return -ENOMEM;
 175
 176         match = of_match_device(st_wdog_match, dev);
 177         if (!match) {
 178                 dev_err(dev, "Couldn't match device\n");
 179                 return -ENODEV;
 180         }
 181         st_wdog->syscfg = (struct st_wdog_syscfg *)match->data;
 182
 183         base = devm_platform_ioremap_resource(pdev, 0);
 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(dev, "No syscfg phandle specified\n");
 190                 return PTR_ERR(regmap);
 191         }
 192
 193         clk = devm_clk_get(dev, NULL);
 194         if (IS_ERR(clk)) {
 195                 dev_err(dev, "Unable to request clock\n");
 196                 return PTR_ERR(clk);
 197         }
 198
 199         st_wdog->dev            = 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(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 = dev;
 212
 213         ret = clk_prepare_enable(clk);
 214         if (ret) {
 215                 dev_err(dev, "Unable to enable clock\n");
 216                 return ret;
 217         }
 218         ret = devm_add_action_or_reset(dev, st_clk_disable_unprepare, clk);
 219         if (ret)
 220                 return ret;
 221
 222         watchdog_set_drvdata(&st_wdog_dev, st_wdog);
 223         watchdog_set_nowayout(&st_wdog_dev, WATCHDOG_NOWAYOUT);
 224
 225         /* Init Watchdog timeout with value in DT */
 226         ret = watchdog_init_timeout(&st_wdog_dev, 0, dev);
 227         if (ret)
 228                 return ret;
 229
 230         ret = devm_watchdog_register_device(dev, &st_wdog_dev);
 231         if (ret)
 232                 return ret;
 233
 234         st_wdog_setup(st_wdog, true);
 235
 236         dev_info(dev, "LPC Watchdog driver registered, reset type is %s",
 237                  st_wdog->warm_reset ? "warm" : "cold");
 238
 239         return ret;
 240 }
 241
 242 static void st_wdog_remove(struct platform_device *pdev)
 243 {
 244         struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
 245
 246         st_wdog_setup(st_wdog, false);
 247 }
 248
 249 static int st_wdog_suspend(struct device *dev)
 250 {
 251         struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
 252
 253         if (watchdog_active(&st_wdog_dev))
 254                 st_wdog_stop(&st_wdog_dev);
 255
 256         st_wdog_setup(st_wdog, false);
 257
 258         clk_disable(st_wdog->clk);
 259
 260         return 0;
 261 }
 262
 263 static int st_wdog_resume(struct device *dev)
 264 {
 265         struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
 266         int ret;
 267
 268         ret = clk_enable(st_wdog->clk);
 269         if (ret) {
 270                 dev_err(dev, "Unable to re-enable clock\n");
 271                 watchdog_unregister_device(&st_wdog_dev);
 272                 clk_unprepare(st_wdog->clk);
 273                 return ret;
 274         }
 275
 276         st_wdog_setup(st_wdog, true);
 277
 278         if (watchdog_active(&st_wdog_dev)) {
 279                 st_wdog_load_timer(st_wdog, st_wdog_dev.timeout);
 280                 st_wdog_start(&st_wdog_dev);
 281         }
 282
 283         return 0;
 284 }
 285
 286 static DEFINE_SIMPLE_DEV_PM_OPS(st_wdog_pm_ops,
 287                                 st_wdog_suspend, st_wdog_resume);
 288
 289 static struct platform_driver st_wdog_driver = {
 290         .driver = {
 291                 .name = "st-lpc-wdt",
 292                 .pm = pm_sleep_ptr(&st_wdog_pm_ops),
 293                 .of_match_table = st_wdog_match,
 294         },
 295         .probe = st_wdog_probe,
 296         .remove_new = st_wdog_remove,
 297 };
 298 module_platform_driver(st_wdog_driver);
 299
 300 MODULE_AUTHOR("David Paris <david.paris@st.com>");
 301 MODULE_DESCRIPTION("ST LPC Watchdog Driver");
 302 MODULE_LICENSE("GPL");