drivers/watchdog/bd9576_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2020 ROHM Semiconductors
   4  *
   5  * ROHM BD9576MUF and BD9573MUF Watchdog driver
   6  */
   7
   8 #include <linux/err.h>
   9 #include <linux/gpio/consumer.h>
  10 #include <linux/mfd/rohm-bd957x.h>
  11 #include <linux/module.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/property.h>
  14 #include <linux/regmap.h>
  15 #include <linux/watchdog.h>
  16
  17 static bool nowayout;
  18 module_param(nowayout, bool, 0);
  19 MODULE_PARM_DESC(nowayout,
  20                 "Watchdog cannot be stopped once started (default=\"false\")");
  21
  22 #define HW_MARGIN_MIN 2
  23 #define HW_MARGIN_MAX 4416
  24 #define BD957X_WDT_DEFAULT_MARGIN 4416
  25 #define WATCHDOG_TIMEOUT 30
  26
  27 struct bd9576_wdt_priv {
  28         struct gpio_desc        *gpiod_ping;
  29         struct gpio_desc        *gpiod_en;
  30         struct device           *dev;
  31         struct regmap           *regmap;
  32         struct watchdog_device  wdd;
  33 };
  34
  35 static void bd9576_wdt_disable(struct bd9576_wdt_priv *priv)
  36 {
  37         gpiod_set_value_cansleep(priv->gpiod_en, 0);
  38 }
  39
  40 static int bd9576_wdt_ping(struct watchdog_device *wdd)
  41 {
  42         struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
  43
  44         /* Pulse */
  45         gpiod_set_value_cansleep(priv->gpiod_ping, 1);
  46         gpiod_set_value_cansleep(priv->gpiod_ping, 0);
  47
  48         return 0;
  49 }
  50
  51 static int bd9576_wdt_start(struct watchdog_device *wdd)
  52 {
  53         struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
  54
  55         gpiod_set_value_cansleep(priv->gpiod_en, 1);
  56
  57         return bd9576_wdt_ping(wdd);
  58 }
  59
  60 static int bd9576_wdt_stop(struct watchdog_device *wdd)
  61 {
  62         struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
  63
  64         bd9576_wdt_disable(priv);
  65
  66         return 0;
  67 }
  68
  69 static const struct watchdog_info bd957x_wdt_ident = {
  70         .options        = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
  71                           WDIOF_SETTIMEOUT,
  72         .identity       = "BD957x Watchdog",
  73 };
  74
  75 static const struct watchdog_ops bd957x_wdt_ops = {
  76         .owner          = THIS_MODULE,
  77         .start          = bd9576_wdt_start,
  78         .stop           = bd9576_wdt_stop,
  79         .ping           = bd9576_wdt_ping,
  80 };
  81
  82 /* Unit is hundreds of uS */
  83 #define FASTNG_MIN 23
  84
  85 static int find_closest_fast(int target, int *sel, int *val)
  86 {
  87         int i;
  88         int window = FASTNG_MIN;
  89
  90         for (i = 0; i < 8 && window < target; i++)
  91                 window <<= 1;
  92
  93         *val = window;
  94         *sel = i;
  95
  96         if (i == 8)
  97                 return -EINVAL;
  98
  99         return 0;
 100
 101 }
 102
 103 static int find_closest_slow_by_fast(int fast_val, int target, int *slowsel)
 104 {
 105         int sel;
 106         static const int multipliers[] = {2, 3, 7, 15};
 107
 108         for (sel = 0; sel < ARRAY_SIZE(multipliers) &&
 109              multipliers[sel] * fast_val < target; sel++)
 110                 ;
 111
 112         if (sel == ARRAY_SIZE(multipliers))
 113                 return -EINVAL;
 114
 115         *slowsel = sel;
 116
 117         return 0;
 118 }
 119
 120 static int find_closest_slow(int target, int *slow_sel, int *fast_sel)
 121 {
 122         static const int multipliers[] = {2, 3, 7, 15};
 123         int i, j;
 124         int val = 0;
 125         int window = FASTNG_MIN;
 126
 127         for (i = 0; i < 8; i++) {
 128                 for (j = 0; j < ARRAY_SIZE(multipliers); j++) {
 129                         int slow;
 130
 131                         slow = window * multipliers[j];
 132                         if (slow >= target && (!val || slow < val)) {
 133                                 val = slow;
 134                                 *fast_sel = i;
 135                                 *slow_sel = j;
 136                         }
 137                 }
 138                 window <<= 1;
 139         }
 140         if (!val)
 141                 return -EINVAL;
 142
 143         return 0;
 144 }
 145
 146 #define BD957X_WDG_TYPE_WINDOW BIT(5)
 147 #define BD957X_WDG_TYPE_SLOW 0
 148 #define BD957X_WDG_TYPE_MASK BIT(5)
 149 #define BD957X_WDG_NG_RATIO_MASK 0x18
 150 #define BD957X_WDG_FASTNG_MASK 0x7
 151
 152 static int bd957x_set_wdt_mode(struct bd9576_wdt_priv *priv, int hw_margin,
 153                                int hw_margin_min)
 154 {
 155         int ret, fastng, slowng, type, reg, mask;
 156         struct device *dev = priv->dev;
 157
 158         /* convert to 100uS */
 159         hw_margin *= 10;
 160         hw_margin_min *= 10;
 161         if (hw_margin_min) {
 162                 int min;
 163
 164                 type = BD957X_WDG_TYPE_WINDOW;
 165                 dev_dbg(dev, "Setting type WINDOW 0x%x\n", type);
 166                 ret = find_closest_fast(hw_margin_min, &fastng, &min);
 167                 if (ret) {
 168                         dev_err(dev, "bad WDT window for fast timeout\n");
 169                         return ret;
 170                 }
 171
 172                 ret = find_closest_slow_by_fast(min, hw_margin, &slowng);
 173                 if (ret) {
 174                         dev_err(dev, "bad WDT window\n");
 175                         return ret;
 176                 }
 177
 178         } else {
 179                 type = BD957X_WDG_TYPE_SLOW;
 180                 dev_dbg(dev, "Setting type SLOW 0x%x\n", type);
 181                 ret = find_closest_slow(hw_margin, &slowng, &fastng);
 182                 if (ret) {
 183                         dev_err(dev, "bad WDT window\n");
 184                         return ret;
 185                 }
 186         }
 187
 188         slowng <<= ffs(BD957X_WDG_NG_RATIO_MASK) - 1;
 189         reg = type | slowng | fastng;
 190         mask = BD957X_WDG_TYPE_MASK | BD957X_WDG_NG_RATIO_MASK |
 191                BD957X_WDG_FASTNG_MASK;
 192         ret = regmap_update_bits(priv->regmap, BD957X_REG_WDT_CONF,
 193                                  mask, reg);
 194
 195         return ret;
 196 }
 197
 198 static int bd9576_wdt_probe(struct platform_device *pdev)
 199 {
 200         struct device *dev = &pdev->dev;
 201         struct bd9576_wdt_priv *priv;
 202         u32 hw_margin[2];
 203         u32 hw_margin_max = BD957X_WDT_DEFAULT_MARGIN, hw_margin_min = 0;
 204         int count;
 205         int ret;
 206
 207         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 208         if (!priv)
 209                 return -ENOMEM;
 210
 211         platform_set_drvdata(pdev, priv);
 212
 213         priv->dev = dev;
 214         priv->regmap = dev_get_regmap(dev->parent, NULL);
 215         if (!priv->regmap) {
 216                 dev_err(dev, "No regmap found\n");
 217                 return -ENODEV;
 218         }
 219
 220         priv->gpiod_en = devm_fwnode_gpiod_get(dev, dev_fwnode(dev->parent),
 221                                                "rohm,watchdog-enable",
 222                                                GPIOD_OUT_LOW,
 223                                                "watchdog-enable");
 224         if (IS_ERR(priv->gpiod_en))
 225                 return dev_err_probe(dev, PTR_ERR(priv->gpiod_en),
 226                               "getting watchdog-enable GPIO failed\n");
 227
 228         priv->gpiod_ping = devm_fwnode_gpiod_get(dev, dev_fwnode(dev->parent),
 229                                                  "rohm,watchdog-ping",
 230                                                  GPIOD_OUT_LOW,
 231                                                  "watchdog-ping");
 232         if (IS_ERR(priv->gpiod_ping))
 233                 return dev_err_probe(dev, PTR_ERR(priv->gpiod_ping),
 234                                      "getting watchdog-ping GPIO failed\n");
 235
 236         count = device_property_count_u32(dev->parent, "rohm,hw-timeout-ms");
 237         if (count < 0 && count != -EINVAL)
 238                 return count;
 239
 240         if (count > 0) {
 241                 if (count > ARRAY_SIZE(hw_margin))
 242                         return -EINVAL;
 243
 244                 ret = device_property_read_u32_array(dev->parent,
 245                                                      "rohm,hw-timeout-ms",
 246                                                      hw_margin, count);
 247                 if (ret < 0)
 248                         return ret;
 249
 250                 if (count == 1)
 251                         hw_margin_max = hw_margin[0];
 252
 253                 if (count == 2) {
 254                         hw_margin_max = hw_margin[1];
 255                         hw_margin_min = hw_margin[0];
 256                 }
 257         }
 258
 259         ret = bd957x_set_wdt_mode(priv, hw_margin_max, hw_margin_min);
 260         if (ret)
 261                 return ret;
 262
 263         watchdog_set_drvdata(&priv->wdd, priv);
 264
 265         priv->wdd.info                  = &bd957x_wdt_ident;
 266         priv->wdd.ops                   = &bd957x_wdt_ops;
 267         priv->wdd.min_hw_heartbeat_ms   = hw_margin_min;
 268         priv->wdd.max_hw_heartbeat_ms   = hw_margin_max;
 269         priv->wdd.parent                = dev;
 270         priv->wdd.timeout               = WATCHDOG_TIMEOUT;
 271
 272         watchdog_init_timeout(&priv->wdd, 0, dev);
 273         watchdog_set_nowayout(&priv->wdd, nowayout);
 274
 275         watchdog_stop_on_reboot(&priv->wdd);
 276
 277         return devm_watchdog_register_device(dev, &priv->wdd);
 278 }
 279
 280 static struct platform_driver bd9576_wdt_driver = {
 281         .driver = {
 282                 .name = "bd9576-wdt",
 283         },
 284         .probe  = bd9576_wdt_probe,
 285 };
 286
 287 module_platform_driver(bd9576_wdt_driver);
 288
 289 MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>");
 290 MODULE_DESCRIPTION("ROHM BD9576/BD9573 Watchdog driver");
 291 MODULE_LICENSE("GPL");
 292 MODULE_ALIAS("platform:bd9576-wdt");