drivers/watchdog/cgbc_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Congatec Board Controller watchdog driver
   4  *
   5  * Copyright (C) 2024 Bootlin
   6  * Author: Thomas Richard <thomas.richard@bootlin.com>
   7  */
   8
   9 #include <linux/build_bug.h>
  10 #include <linux/device.h>
  11 #include <linux/limits.h>
  12 #include <linux/module.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/watchdog.h>
  15
  16 #include <linux/mfd/cgbc.h>
  17
  18 #define CGBC_WDT_CMD_TRIGGER    0x27
  19 #define CGBC_WDT_CMD_INIT       0x28
  20 #define CGBC_WDT_DISABLE        0x00
  21
  22 #define CGBC_WDT_MODE_SINGLE_EVENT 0x02
  23
  24 #define CGBC_WDT_MIN_TIMEOUT    1
  25 #define CGBC_WDT_MAX_TIMEOUT    ((U32_MAX >> 8) / 1000)
  26
  27 #define CGBC_WDT_DEFAULT_TIMEOUT        30
  28 #define CGBC_WDT_DEFAULT_PRETIMEOUT     0
  29
  30 enum action {
  31         ACTION_INT = 0,
  32         ACTION_SMI,
  33         ACTION_RESET,
  34         ACTION_BUTTON,
  35 };
  36
  37 static unsigned int timeout;
  38 module_param(timeout, uint, 0);
  39 MODULE_PARM_DESC(timeout,
  40                  "Watchdog timeout in seconds. (>=0, default="
  41                  __MODULE_STRING(CGBC_WDT_DEFAULT_TIMEOUT) ")");
  42
  43 static unsigned int pretimeout = CGBC_WDT_DEFAULT_PRETIMEOUT;
  44 module_param(pretimeout, uint, 0);
  45 MODULE_PARM_DESC(pretimeout,
  46                  "Watchdog pretimeout in seconds. (>=0, default="
  47                  __MODULE_STRING(CGBC_WDT_DEFAULT_PRETIMEOUT) ")");
  48
  49 static bool nowayout = WATCHDOG_NOWAYOUT;
  50 module_param(nowayout, bool, 0);
  51 MODULE_PARM_DESC(nowayout,
  52                  "Watchdog cannot be stopped once started (default="
  53                  __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  54
  55 struct cgbc_wdt_data {
  56         struct cgbc_device_data *cgbc;
  57         struct watchdog_device  wdd;
  58 };
  59
  60 struct cgbc_wdt_cmd_cfg {
  61         u8 cmd;
  62         u8 mode;
  63         u8 action;
  64         u8 timeout1[3];
  65         u8 timeout2[3];
  66         u8 reserved[3];
  67         u8 delay[3];
  68 } __packed;
  69
  70 static_assert(sizeof(struct cgbc_wdt_cmd_cfg) == 15);
  71
  72 static int cgbc_wdt_start(struct watchdog_device *wdd)
  73 {
  74         struct cgbc_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
  75         struct cgbc_device_data *cgbc = wdt_data->cgbc;
  76         unsigned int timeout1 = (wdd->timeout - wdd->pretimeout) * 1000;
  77         unsigned int timeout2 = wdd->pretimeout * 1000;
  78         u8 action;
  79
  80         struct cgbc_wdt_cmd_cfg cmd_start = {
  81                 .cmd = CGBC_WDT_CMD_INIT,
  82                 .mode = CGBC_WDT_MODE_SINGLE_EVENT,
  83                 .timeout1[0] = (u8)timeout1,
  84                 .timeout1[1] = (u8)(timeout1 >> 8),
  85                 .timeout1[2] = (u8)(timeout1 >> 16),
  86                 .timeout2[0] = (u8)timeout2,
  87                 .timeout2[1] = (u8)(timeout2 >> 8),
  88                 .timeout2[2] = (u8)(timeout2 >> 16),
  89         };
  90
  91         if (wdd->pretimeout) {
  92                 action = 2;
  93                 action |= ACTION_SMI << 2;
  94                 action |= ACTION_RESET << 4;
  95         } else {
  96                 action = 1;
  97                 action |= ACTION_RESET << 2;
  98         }
  99
 100         cmd_start.action = action;
 101
 102         return cgbc_command(cgbc, &cmd_start, sizeof(cmd_start), NULL, 0, NULL);
 103 }
 104
 105 static int cgbc_wdt_stop(struct watchdog_device *wdd)
 106 {
 107         struct cgbc_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 108         struct cgbc_device_data *cgbc = wdt_data->cgbc;
 109         struct cgbc_wdt_cmd_cfg cmd_stop = {
 110                 .cmd = CGBC_WDT_CMD_INIT,
 111                 .mode = CGBC_WDT_DISABLE,
 112         };
 113
 114         return cgbc_command(cgbc, &cmd_stop, sizeof(cmd_stop), NULL, 0, NULL);
 115 }
 116
 117 static int cgbc_wdt_keepalive(struct watchdog_device *wdd)
 118 {
 119         struct cgbc_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 120         struct cgbc_device_data *cgbc = wdt_data->cgbc;
 121         u8 cmd_ping = CGBC_WDT_CMD_TRIGGER;
 122
 123         return cgbc_command(cgbc, &cmd_ping, sizeof(cmd_ping), NULL, 0, NULL);
 124 }
 125
 126 static int cgbc_wdt_set_pretimeout(struct watchdog_device *wdd,
 127                                    unsigned int pretimeout)
 128 {
 129         wdd->pretimeout = pretimeout;
 130
 131         if (watchdog_active(wdd))
 132                 return cgbc_wdt_start(wdd);
 133
 134         return 0;
 135 }
 136
 137 static int cgbc_wdt_set_timeout(struct watchdog_device *wdd,
 138                                 unsigned int timeout)
 139 {
 140         if (timeout < wdd->pretimeout)
 141                 wdd->pretimeout = 0;
 142
 143         wdd->timeout = timeout;
 144
 145         if (watchdog_active(wdd))
 146                 return cgbc_wdt_start(wdd);
 147
 148         return 0;
 149 }
 150
 151 static const struct watchdog_info cgbc_wdt_info = {
 152         .identity       = "CGBC Watchdog",
 153         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 154                 WDIOF_MAGICCLOSE | WDIOF_PRETIMEOUT
 155 };
 156
 157 static const struct watchdog_ops cgbc_wdt_ops = {
 158         .owner          = THIS_MODULE,
 159         .start          = cgbc_wdt_start,
 160         .stop           = cgbc_wdt_stop,
 161         .ping           = cgbc_wdt_keepalive,
 162         .set_timeout    = cgbc_wdt_set_timeout,
 163         .set_pretimeout = cgbc_wdt_set_pretimeout,
 164 };
 165
 166 static int cgbc_wdt_probe(struct platform_device *pdev)
 167 {
 168         struct cgbc_device_data *cgbc = dev_get_drvdata(pdev->dev.parent);
 169         struct device *dev = &pdev->dev;
 170         struct cgbc_wdt_data *wdt_data;
 171         struct watchdog_device *wdd;
 172
 173         wdt_data = devm_kzalloc(dev, sizeof(*wdt_data), GFP_KERNEL);
 174         if (!wdt_data)
 175                 return -ENOMEM;
 176
 177         wdt_data->cgbc = cgbc;
 178         wdd = &wdt_data->wdd;
 179         wdd->parent = dev;
 180
 181         wdd->info = &cgbc_wdt_info;
 182         wdd->ops = &cgbc_wdt_ops;
 183         wdd->max_timeout = CGBC_WDT_MAX_TIMEOUT;
 184         wdd->min_timeout = CGBC_WDT_MIN_TIMEOUT;
 185
 186         watchdog_set_drvdata(wdd, wdt_data);
 187         watchdog_set_nowayout(wdd, nowayout);
 188
 189         wdd->timeout = CGBC_WDT_DEFAULT_TIMEOUT;
 190         watchdog_init_timeout(wdd, timeout, dev);
 191         cgbc_wdt_set_pretimeout(wdd, pretimeout);
 192
 193         platform_set_drvdata(pdev, wdt_data);
 194         watchdog_stop_on_reboot(wdd);
 195         watchdog_stop_on_unregister(wdd);
 196
 197         return devm_watchdog_register_device(dev, wdd);
 198 }
 199
 200 static struct platform_driver cgbc_wdt_driver = {
 201         .driver         = {
 202                 .name   = "cgbc-wdt",
 203         },
 204         .probe          = cgbc_wdt_probe,
 205 };
 206
 207 module_platform_driver(cgbc_wdt_driver);
 208
 209 MODULE_DESCRIPTION("Congatec Board Controller Watchdog Driver");
 210 MODULE_AUTHOR("Thomas Richard <thomas.richard@bootlin.com>");
 211 MODULE_LICENSE("GPL");