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