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/of.h>
  13 #include <linux/platform_device.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         bool                    always_running;
  33         struct watchdog_device  wdd;
  34 };
  35
  36 static void bd9576_wdt_disable(struct bd9576_wdt_priv *priv)
  37 {
  38         gpiod_set_value_cansleep(priv->gpiod_en, 0);
  39 }
  40
  41 static int bd9576_wdt_ping(struct watchdog_device *wdd)
  42 {
  43         struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
  44
  45         /* Pulse */
  46         gpiod_set_value_cansleep(priv->gpiod_ping, 1);
  47         gpiod_set_value_cansleep(priv->gpiod_ping, 0);
  48
  49         return 0;
  50 }
  51
  52 static int bd9576_wdt_start(struct watchdog_device *wdd)
  53 {
  54         struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
  55
  56         gpiod_set_value_cansleep(priv->gpiod_en, 1);
  57
  58         return bd9576_wdt_ping(wdd);
  59 }
  60
  61 static int bd9576_wdt_stop(struct watchdog_device *wdd)
  62 {
  63         struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
  64
  65         if (!priv->always_running)
  66                 bd9576_wdt_disable(priv);
  67         else
  68                 set_bit(WDOG_HW_RUNNING, &wdd->status);
  69
  70         return 0;
  71 }
  72
  73 static const struct watchdog_info bd957x_wdt_ident = {
  74         .options        = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
  75                           WDIOF_SETTIMEOUT,
  76         .identity       = "BD957x Watchdog",
  77 };
  78
  79 static const struct watchdog_ops bd957x_wdt_ops = {
  80         .owner          = THIS_MODULE,
  81         .start          = bd9576_wdt_start,
  82         .stop           = bd9576_wdt_stop,
  83         .ping           = bd9576_wdt_ping,
  84 };
  85
  86 /* Unit is hundreds of uS */
  87 #define FASTNG_MIN 23
  88
  89 static int find_closest_fast(int target, int *sel, int *val)
  90 {
  91         int i;
  92         int window = FASTNG_MIN;
  93
  94         for (i = 0; i < 8 && window < target; i++)
  95                 window <<= 1;
  96
  97         *val = window;
  98         *sel = i;
  99
 100         if (i == 8)
 101                 return -EINVAL;
 102
 103         return 0;
 104
 105 }
 106
 107 static int find_closest_slow_by_fast(int fast_val, int target, int *slowsel)
 108 {
 109         int sel;
 110         static const int multipliers[] = {2, 3, 7, 15};
 111
 112         for (sel = 0; sel < ARRAY_SIZE(multipliers) &&
 113              multipliers[sel] * fast_val < target; sel++)
 114                 ;
 115
 116         if (sel == ARRAY_SIZE(multipliers))
 117                 return -EINVAL;
 118
 119         *slowsel = sel;
 120
 121         return 0;
 122 }
 123
 124 static int find_closest_slow(int target, int *slow_sel, int *fast_sel)
 125 {
 126         static const int multipliers[] = {2, 3, 7, 15};
 127         int i, j;
 128         int val = 0;
 129         int window = FASTNG_MIN;
 130
 131         for (i = 0; i < 8; i++) {
 132                 for (j = 0; j < ARRAY_SIZE(multipliers); j++) {
 133                         int slow;
 134
 135                         slow = window * multipliers[j];
 136                         if (slow >= target && (!val || slow < val)) {
 137                                 val = slow;
 138                                 *fast_sel = i;
 139                                 *slow_sel = j;
 140                         }
 141                 }
 142                 window <<= 1;
 143         }
 144         if (!val)
 145                 return -EINVAL;
 146
 147         return 0;
 148 }
 149
 150 #define BD957X_WDG_TYPE_WINDOW BIT(5)
 151 #define BD957X_WDG_TYPE_SLOW 0
 152 #define BD957X_WDG_TYPE_MASK BIT(5)
 153 #define BD957X_WDG_NG_RATIO_MASK 0x18
 154 #define BD957X_WDG_FASTNG_MASK 0x7
 155
 156 static int bd957x_set_wdt_mode(struct bd9576_wdt_priv *priv, int hw_margin,
 157                                int hw_margin_min)
 158 {
 159         int ret, fastng, slowng, type, reg, mask;
 160         struct device *dev = priv->dev;
 161
 162         /* convert to 100uS */
 163         hw_margin *= 10;
 164         hw_margin_min *= 10;
 165         if (hw_margin_min) {
 166                 int min;
 167
 168                 type = BD957X_WDG_TYPE_WINDOW;
 169                 dev_dbg(dev, "Setting type WINDOW 0x%x\n", type);
 170                 ret = find_closest_fast(hw_margin_min, &fastng, &min);
 171                 if (ret) {
 172                         dev_err(dev, "bad WDT window for fast timeout\n");
 173                         return ret;
 174                 }
 175
 176                 ret = find_closest_slow_by_fast(min, hw_margin, &slowng);
 177                 if (ret) {
 178                         dev_err(dev, "bad WDT window\n");
 179                         return ret;
 180                 }
 181
 182         } else {
 183                 type = BD957X_WDG_TYPE_SLOW;
 184                 dev_dbg(dev, "Setting type SLOW 0x%x\n", type);
 185                 ret = find_closest_slow(hw_margin, &slowng, &fastng);
 186                 if (ret) {
 187                         dev_err(dev, "bad WDT window\n");
 188                         return ret;
 189                 }
 190         }
 191
 192         slowng <<= ffs(BD957X_WDG_NG_RATIO_MASK) - 1;
 193         reg = type | slowng | fastng;
 194         mask = BD957X_WDG_TYPE_MASK | BD957X_WDG_NG_RATIO_MASK |
 195                BD957X_WDG_FASTNG_MASK;
 196         ret = regmap_update_bits(priv->regmap, BD957X_REG_WDT_CONF,
 197                                  mask, reg);
 198
 199         return ret;
 200 }
 201
 202 static int bd9576_wdt_probe(struct platform_device *pdev)
 203 {
 204         struct device *dev = &pdev->dev;
 205         struct device_node *np = dev->parent->of_node;
 206         struct bd9576_wdt_priv *priv;
 207         u32 hw_margin[2];
 208         u32 hw_margin_max = BD957X_WDT_DEFAULT_MARGIN, hw_margin_min = 0;
 209         int ret;
 210
 211         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 212         if (!priv)
 213                 return -ENOMEM;
 214
 215         platform_set_drvdata(pdev, priv);
 216
 217         priv->dev = dev;
 218         priv->regmap = dev_get_regmap(dev->parent, NULL);
 219         if (!priv->regmap) {
 220                 dev_err(dev, "No regmap found\n");
 221                 return -ENODEV;
 222         }
 223
 224         priv->gpiod_en = devm_gpiod_get_from_of_node(dev, dev->parent->of_node,
 225                                                      "rohm,watchdog-enable-gpios",
 226                                                      0, GPIOD_OUT_LOW,
 227                                                      "watchdog-enable");
 228         if (IS_ERR(priv->gpiod_en))
 229                 return dev_err_probe(dev, PTR_ERR(priv->gpiod_en),
 230                               "getting watchdog-enable GPIO failed\n");
 231
 232         priv->gpiod_ping = devm_gpiod_get_from_of_node(dev, dev->parent->of_node,
 233                                                      "rohm,watchdog-ping-gpios",
 234                                                      0, GPIOD_OUT_LOW,
 235                                                      "watchdog-ping");
 236         if (IS_ERR(priv->gpiod_ping))
 237                 return dev_err_probe(dev, PTR_ERR(priv->gpiod_ping),
 238                                      "getting watchdog-ping GPIO failed\n");
 239
 240         ret = of_property_read_variable_u32_array(np, "rohm,hw-timeout-ms",
 241                                                   &hw_margin[0], 1, 2);
 242         if (ret < 0 && ret != -EINVAL)
 243                 return ret;
 244
 245         if (ret == 1)
 246                 hw_margin_max = hw_margin[0];
 247
 248         if (ret == 2) {
 249                 hw_margin_max = hw_margin[1];
 250                 hw_margin_min = hw_margin[0];
 251         }
 252
 253         ret = bd957x_set_wdt_mode(priv, hw_margin_max, hw_margin_min);
 254         if (ret)
 255                 return ret;
 256
 257         priv->always_running = of_property_read_bool(np, "always-running");
 258
 259         watchdog_set_drvdata(&priv->wdd, priv);
 260
 261         priv->wdd.info                  = &bd957x_wdt_ident;
 262         priv->wdd.ops                   = &bd957x_wdt_ops;
 263         priv->wdd.min_hw_heartbeat_ms   = hw_margin_min;
 264         priv->wdd.max_hw_heartbeat_ms   = hw_margin_max;
 265         priv->wdd.parent                = dev;
 266         priv->wdd.timeout               = WATCHDOG_TIMEOUT;
 267
 268         watchdog_init_timeout(&priv->wdd, 0, dev);
 269         watchdog_set_nowayout(&priv->wdd, nowayout);
 270
 271         watchdog_stop_on_reboot(&priv->wdd);
 272
 273         if (priv->always_running)
 274                 bd9576_wdt_start(&priv->wdd);
 275
 276         return devm_watchdog_register_device(dev, &priv->wdd);
 277 }
 278
 279 static struct platform_driver bd9576_wdt_driver = {
 280         .driver = {
 281                 .name = "bd9576-wdt",
 282         },
 283         .probe  = bd9576_wdt_probe,
 284 };
 285
 286 module_platform_driver(bd9576_wdt_driver);
 287
 288 MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>");
 289 MODULE_DESCRIPTION("ROHM BD9576/BD9573 Watchdog driver");
 290 MODULE_LICENSE("GPL");
 291 MODULE_ALIAS("platform:bd9576-wdt");