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 .identity = "Renesas WDT Watchdog", 126 }; 127 128 static const struct watchdog_ops rwdt_ops = { 129 .owner = THIS_MODULE, 130 .start = rwdt_start, 131 .stop = rwdt_stop, 132 .ping = rwdt_init_timeout, 133 .get_timeleft = rwdt_get_timeleft, 134 .restart = rwdt_restart, 135 }; 136 137 #if defined(CONFIG_ARCH_RCAR_GEN2) && defined(CONFIG_SMP) 138 /* 139 * Watchdog-reset integration is broken on early revisions of R-Car Gen2 SoCs 140 */ 141 static const struct soc_device_attribute rwdt_quirks_match[] = { 142 { 143 .soc_id = "r8a7790", 144 .revision = "ES1.*", 145 .data = (void *)1, /* needs single CPU */ 146 }, { 147 .soc_id = "r8a7791", 148 .revision = "ES[12].*", 149 .data = (void *)1, /* needs single CPU */ 150 }, { 151 .soc_id = "r8a7792", 152 .revision = "*", 153 .data = (void *)0, /* needs SMP disabled */ 154 }, 155 { /* sentinel */ } 156 }; 157 158 static bool rwdt_blacklisted(struct device *dev) 159 { 160 const struct soc_device_attribute *attr; 161 162 attr = soc_device_match(rwdt_quirks_match); 163 if (attr && setup_max_cpus > (uintptr_t)attr->data) { 164 dev_info(dev, "Watchdog blacklisted on %s %s\n", attr->soc_id, 165 attr->revision); 166 return true; 167 } 168 169 return false; 170 } 171 #else /* !CONFIG_ARCH_RCAR_GEN2 || !CONFIG_SMP */ 172 static inline bool rwdt_blacklisted(struct device *dev) { return false; } 173 #endif /* !CONFIG_ARCH_RCAR_GEN2 || !CONFIG_SMP */ 174 175 static int rwdt_probe(struct platform_device *pdev) 176 { 177 struct rwdt_priv *priv; 178 struct resource *res; 179 struct clk *clk; 180 unsigned long clks_per_sec; 181 int ret, i; 182 183 if (rwdt_blacklisted(&pdev->dev)) 184 return -ENODEV; 185 186 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); 187 if (!priv) 188 return -ENOMEM; 189 190 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 191 priv->base = devm_ioremap_resource(&pdev->dev, res); 192 if (IS_ERR(priv->base)) 193 return PTR_ERR(priv->base); 194 195 clk = devm_clk_get(&pdev->dev, NULL); 196 if (IS_ERR(clk)) 197 return PTR_ERR(clk); 198 199 pm_runtime_enable(&pdev->dev); 200 201 pm_runtime_get_sync(&pdev->dev); 202 priv->clk_rate = clk_get_rate(clk); 203 pm_runtime_put(&pdev->dev); 204 205 if (!priv->clk_rate) { 206 ret = -ENOENT; 207 goto out_pm_disable; 208 } 209 210 for (i = ARRAY_SIZE(clk_divs) - 1; i >= 0; i--) { 211 clks_per_sec = priv->clk_rate / clk_divs[i]; 212 if (clks_per_sec && clks_per_sec < 65536) { 213 priv->cks = i; 214 break; 215 } 216 } 217 218 if (i < 0) { 219 dev_err(&pdev->dev, "Can't find suitable clock divider\n"); 220 ret = -ERANGE; 221 goto out_pm_disable; 222 } 223 224 priv->wdev.info = &rwdt_ident, 225 priv->wdev.ops = &rwdt_ops, 226 priv->wdev.parent = &pdev->dev; 227 priv->wdev.min_timeout = 1; 228 priv->wdev.max_timeout = DIV_BY_CLKS_PER_SEC(priv, 65536); 229 priv->wdev.timeout = min(priv->wdev.max_timeout, RWDT_DEFAULT_TIMEOUT); 230 231 platform_set_drvdata(pdev, priv); 232 watchdog_set_drvdata(&priv->wdev, priv); 233 watchdog_set_nowayout(&priv->wdev, nowayout); 234 watchdog_set_restart_priority(&priv->wdev, 0); 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