drivers/watchdog/renesas_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Watchdog driver for Renesas WDT watchdog
   4  *
   5  * Copyright (C) 2015-17 Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
   6  * Copyright (C) 2015-17 Renesas Electronics Corporation
   7  */
   8 #include <linux/bitops.h>
   9 #include <linux/clk.h>
  10 #include <linux/delay.h>
  11 #include <linux/io.h>
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/of.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/pm_runtime.h>
  17 #include <linux/smp.h>
  18 #include <linux/sys_soc.h>
  19 #include <linux/watchdog.h>
  20
  21 #define RWTCNT          0
  22 #define RWTCSRA         4
  23 #define RWTCSRA_WOVF    BIT(4)
  24 #define RWTCSRA_WRFLG   BIT(5)
  25 #define RWTCSRA_TME     BIT(7)
  26 #define RWTCSRB         8
  27
  28 #define RWDT_DEFAULT_TIMEOUT 60U
  29
  30 /*
  31  * In probe, clk_rate is checked to be not more than 16 bit * biggest clock
  32  * divider (12 bits). d is only a factor to fully utilize the WDT counter and
  33  * will not exceed its 16 bits. Thus, no overflow, we stay below 32 bits.
  34  */
  35 #define MUL_BY_CLKS_PER_SEC(p, d) \
  36         DIV_ROUND_UP((d) * (p)->clk_rate, clk_divs[(p)->cks])
  37
  38 /* d is 16 bit, clk_divs 12 bit -> no 32 bit overflow */
  39 #define DIV_BY_CLKS_PER_SEC(p, d) ((d) * clk_divs[(p)->cks] / (p)->clk_rate)
  40
  41 static const unsigned int clk_divs[] = { 1, 4, 16, 32, 64, 128, 1024, 4096 };
  42
  43 static bool nowayout = WATCHDOG_NOWAYOUT;
  44 module_param(nowayout, bool, 0);
  45 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  46                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  47
  48 struct rwdt_priv {
  49         void __iomem *base;
  50         struct watchdog_device wdev;
  51         unsigned long clk_rate;
  52         u8 cks;
  53 };
  54
  55 static void rwdt_write(struct rwdt_priv *priv, u32 val, unsigned int reg)
  56 {
  57         if (reg == RWTCNT)
  58                 val |= 0x5a5a0000;
  59         else
  60                 val |= 0xa5a5a500;
  61
  62         writel_relaxed(val, priv->base + reg);
  63 }
  64
  65 static int rwdt_init_timeout(struct watchdog_device *wdev)
  66 {
  67         struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
  68
  69         rwdt_write(priv, 65536 - MUL_BY_CLKS_PER_SEC(priv, wdev->timeout), RWTCNT);
  70
  71         return 0;
  72 }
  73
  74 static void rwdt_wait_cycles(struct rwdt_priv *priv, unsigned int cycles)
  75 {
  76         unsigned int delay;
  77
  78         delay = DIV_ROUND_UP(cycles * 1000000, priv->clk_rate);
  79
  80         usleep_range(delay, 2 * delay);
  81 }
  82
  83 static int rwdt_start(struct watchdog_device *wdev)
  84 {
  85         struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
  86         u8 val;
  87
  88         pm_runtime_get_sync(wdev->parent);
  89
  90         /* Stop the timer before we modify any register */
  91         val = readb_relaxed(priv->base + RWTCSRA) & ~RWTCSRA_TME;
  92         rwdt_write(priv, val, RWTCSRA);
  93         /* Delay 2 cycles before setting watchdog counter */
  94         rwdt_wait_cycles(priv, 2);
  95
  96         rwdt_init_timeout(wdev);
  97         rwdt_write(priv, priv->cks, RWTCSRA);
  98         rwdt_write(priv, 0, RWTCSRB);
  99
 100         while (readb_relaxed(priv->base + RWTCSRA) & RWTCSRA_WRFLG)
 101                 cpu_relax();
 102
 103         rwdt_write(priv, priv->cks | RWTCSRA_TME, RWTCSRA);
 104
 105         return 0;
 106 }
 107
 108 static int rwdt_stop(struct watchdog_device *wdev)
 109 {
 110         struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
 111
 112         rwdt_write(priv, priv->cks, RWTCSRA);
 113         /* Delay 3 cycles before disabling module clock */
 114         rwdt_wait_cycles(priv, 3);
 115         pm_runtime_put(wdev->parent);
 116
 117         return 0;
 118 }
 119
 120 static unsigned int rwdt_get_timeleft(struct watchdog_device *wdev)
 121 {
 122         struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
 123         u16 val = readw_relaxed(priv->base + RWTCNT);
 124
 125         return DIV_BY_CLKS_PER_SEC(priv, 65536 - val);
 126 }
 127
 128 static int rwdt_restart(struct watchdog_device *wdev, unsigned long action,
 129                         void *data)
 130 {
 131         struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
 132
 133         rwdt_start(wdev);
 134         rwdt_write(priv, 0xffff, RWTCNT);
 135         return 0;
 136 }
 137
 138 static const struct watchdog_info rwdt_ident = {
 139         .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
 140                 WDIOF_CARDRESET,
 141         .identity = "Renesas WDT Watchdog",
 142 };
 143
 144 static const struct watchdog_ops rwdt_ops = {
 145         .owner = THIS_MODULE,
 146         .start = rwdt_start,
 147         .stop = rwdt_stop,
 148         .ping = rwdt_init_timeout,
 149         .get_timeleft = rwdt_get_timeleft,
 150         .restart = rwdt_restart,
 151 };
 152
 153 #if defined(CONFIG_ARCH_RCAR_GEN2) && defined(CONFIG_SMP)
 154 /*
 155  * Watchdog-reset integration is broken on early revisions of R-Car Gen2 SoCs
 156  */
 157 static const struct soc_device_attribute rwdt_quirks_match[] = {
 158         {
 159                 .soc_id = "r8a7790",
 160                 .revision = "ES1.*",
 161                 .data = (void *)1,      /* needs single CPU */
 162         }, {
 163                 .soc_id = "r8a7791",
 164                 .revision = "ES1.*",
 165                 .data = (void *)1,      /* needs single CPU */
 166         }, {
 167                 .soc_id = "r8a7792",
 168                 .data = (void *)0,      /* needs SMP disabled */
 169         },
 170         { /* sentinel */ }
 171 };
 172
 173 static bool rwdt_blacklisted(struct device *dev)
 174 {
 175         const struct soc_device_attribute *attr;
 176
 177         attr = soc_device_match(rwdt_quirks_match);
 178         if (attr && setup_max_cpus > (uintptr_t)attr->data) {
 179                 dev_info(dev, "Watchdog blacklisted on %s %s\n", attr->soc_id,
 180                          attr->revision);
 181                 return true;
 182         }
 183
 184         return false;
 185 }
 186 #else /* !CONFIG_ARCH_RCAR_GEN2 || !CONFIG_SMP */
 187 static inline bool rwdt_blacklisted(struct device *dev) { return false; }
 188 #endif /* !CONFIG_ARCH_RCAR_GEN2 || !CONFIG_SMP */
 189
 190 static int rwdt_probe(struct platform_device *pdev)
 191 {
 192         struct device *dev = &pdev->dev;
 193         struct rwdt_priv *priv;
 194         struct clk *clk;
 195         unsigned long clks_per_sec;
 196         int ret, i;
 197         u8 csra;
 198
 199         if (rwdt_blacklisted(dev))
 200                 return -ENODEV;
 201
 202         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 203         if (!priv)
 204                 return -ENOMEM;
 205
 206         priv->base = devm_platform_ioremap_resource(pdev, 0);
 207         if (IS_ERR(priv->base))
 208                 return PTR_ERR(priv->base);
 209
 210         clk = devm_clk_get(dev, NULL);
 211         if (IS_ERR(clk))
 212                 return PTR_ERR(clk);
 213
 214         pm_runtime_enable(dev);
 215         pm_runtime_get_sync(dev);
 216         priv->clk_rate = clk_get_rate(clk);
 217         csra = readb_relaxed(priv->base + RWTCSRA);
 218         priv->wdev.bootstatus = csra & RWTCSRA_WOVF ? WDIOF_CARDRESET : 0;
 219         pm_runtime_put(dev);
 220
 221         if (!priv->clk_rate) {
 222                 ret = -ENOENT;
 223                 goto out_pm_disable;
 224         }
 225
 226         for (i = ARRAY_SIZE(clk_divs) - 1; i >= 0; i--) {
 227                 clks_per_sec = priv->clk_rate / clk_divs[i];
 228                 if (clks_per_sec && clks_per_sec < 65536) {
 229                         priv->cks = i;
 230                         break;
 231                 }
 232         }
 233
 234         if (i < 0) {
 235                 dev_err(dev, "Can't find suitable clock divider\n");
 236                 ret = -ERANGE;
 237                 goto out_pm_disable;
 238         }
 239
 240         priv->wdev.info = &rwdt_ident;
 241         priv->wdev.ops = &rwdt_ops;
 242         priv->wdev.parent = dev;
 243         priv->wdev.min_timeout = 1;
 244         priv->wdev.max_timeout = DIV_BY_CLKS_PER_SEC(priv, 65536);
 245         priv->wdev.timeout = min(priv->wdev.max_timeout, RWDT_DEFAULT_TIMEOUT);
 246
 247         platform_set_drvdata(pdev, priv);
 248         watchdog_set_drvdata(&priv->wdev, priv);
 249         watchdog_set_nowayout(&priv->wdev, nowayout);
 250         watchdog_set_restart_priority(&priv->wdev, 0);
 251         watchdog_stop_on_unregister(&priv->wdev);
 252
 253         /* This overrides the default timeout only if DT configuration was found */
 254         watchdog_init_timeout(&priv->wdev, 0, dev);
 255
 256         /* Check if FW enabled the watchdog */
 257         if (csra & RWTCSRA_TME) {
 258                 /* Ensure properly initialized dividers */
 259                 rwdt_start(&priv->wdev);
 260                 set_bit(WDOG_HW_RUNNING, &priv->wdev.status);
 261         }
 262
 263         ret = watchdog_register_device(&priv->wdev);
 264         if (ret < 0)
 265                 goto out_pm_disable;
 266
 267         return 0;
 268
 269  out_pm_disable:
 270         pm_runtime_disable(dev);
 271         return ret;
 272 }
 273
 274 static int rwdt_remove(struct platform_device *pdev)
 275 {
 276         struct rwdt_priv *priv = platform_get_drvdata(pdev);
 277
 278         watchdog_unregister_device(&priv->wdev);
 279         pm_runtime_disable(&pdev->dev);
 280
 281         return 0;
 282 }
 283
 284 static int __maybe_unused rwdt_suspend(struct device *dev)
 285 {
 286         struct rwdt_priv *priv = dev_get_drvdata(dev);
 287
 288         if (watchdog_active(&priv->wdev))
 289                 rwdt_stop(&priv->wdev);
 290
 291         return 0;
 292 }
 293
 294 static int __maybe_unused rwdt_resume(struct device *dev)
 295 {
 296         struct rwdt_priv *priv = dev_get_drvdata(dev);
 297
 298         if (watchdog_active(&priv->wdev))
 299                 rwdt_start(&priv->wdev);
 300
 301         return 0;
 302 }
 303
 304 static SIMPLE_DEV_PM_OPS(rwdt_pm_ops, rwdt_suspend, rwdt_resume);
 305
 306 static const struct of_device_id rwdt_ids[] = {
 307         { .compatible = "renesas,rcar-gen2-wdt", },
 308         { .compatible = "renesas,rcar-gen3-wdt", },
 309         { /* sentinel */ }
 310 };
 311 MODULE_DEVICE_TABLE(of, rwdt_ids);
 312
 313 static struct platform_driver rwdt_driver = {
 314         .driver = {
 315                 .name = "renesas_wdt",
 316                 .of_match_table = rwdt_ids,
 317                 .pm = &rwdt_pm_ops,
 318         },
 319         .probe = rwdt_probe,
 320         .remove = rwdt_remove,
 321 };
 322 module_platform_driver(rwdt_driver);
 323
 324 MODULE_DESCRIPTION("Renesas WDT Watchdog Driver");
 325 MODULE_LICENSE("GPL v2");
 326 MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");