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