drivers/platform/cznic/turris-omnia-mcu-watchdog.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * CZ.NIC's Turris Omnia MCU watchdog driver
   4  *
   5  * 2024 by Marek Behún <kabel@kernel.org>
   6  */
   7
   8 #include <linux/bitops.h>
   9 #include <linux/device.h>
  10 #include <linux/i2c.h>
  11 #include <linux/moduleparam.h>
  12 #include <linux/types.h>
  13 #include <linux/units.h>
  14 #include <linux/watchdog.h>
  15
  16 #include <linux/turris-omnia-mcu-interface.h>
  17 #include "turris-omnia-mcu.h"
  18
  19 #define WATCHDOG_TIMEOUT                120
  20
  21 static unsigned int timeout;
  22 module_param(timeout, int, 0);
  23 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
  24
  25 static bool nowayout = WATCHDOG_NOWAYOUT;
  26 module_param(nowayout, bool, 0);
  27 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  28                            __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  29
  30 static int omnia_wdt_start(struct watchdog_device *wdt)
  31 {
  32         struct omnia_mcu *mcu = watchdog_get_drvdata(wdt);
  33
  34         return omnia_cmd_write_u8(mcu->client, OMNIA_CMD_SET_WATCHDOG_STATE, 1);
  35 }
  36
  37 static int omnia_wdt_stop(struct watchdog_device *wdt)
  38 {
  39         struct omnia_mcu *mcu = watchdog_get_drvdata(wdt);
  40
  41         return omnia_cmd_write_u8(mcu->client, OMNIA_CMD_SET_WATCHDOG_STATE, 0);
  42 }
  43
  44 static int omnia_wdt_ping(struct watchdog_device *wdt)
  45 {
  46         struct omnia_mcu *mcu = watchdog_get_drvdata(wdt);
  47
  48         return omnia_cmd_write_u8(mcu->client, OMNIA_CMD_SET_WATCHDOG_STATE, 1);
  49 }
  50
  51 static int omnia_wdt_set_timeout(struct watchdog_device *wdt,
  52                                  unsigned int timeout)
  53 {
  54         struct omnia_mcu *mcu = watchdog_get_drvdata(wdt);
  55
  56         return omnia_cmd_write_u16(mcu->client, OMNIA_CMD_SET_WDT_TIMEOUT,
  57                                    timeout * DECI);
  58 }
  59
  60 static unsigned int omnia_wdt_get_timeleft(struct watchdog_device *wdt)
  61 {
  62         struct omnia_mcu *mcu = watchdog_get_drvdata(wdt);
  63         u16 timeleft;
  64         int err;
  65
  66         err = omnia_cmd_read_u16(mcu->client, OMNIA_CMD_GET_WDT_TIMELEFT,
  67                                  &timeleft);
  68         if (err) {
  69                 dev_err(&mcu->client->dev, "Cannot get watchdog timeleft: %d\n",
  70                         err);
  71                 return 0;
  72         }
  73
  74         return timeleft / DECI;
  75 }
  76
  77 static const struct watchdog_info omnia_wdt_info = {
  78         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
  79         .identity = "Turris Omnia MCU Watchdog",
  80 };
  81
  82 static const struct watchdog_ops omnia_wdt_ops = {
  83         .owner          = THIS_MODULE,
  84         .start          = omnia_wdt_start,
  85         .stop           = omnia_wdt_stop,
  86         .ping           = omnia_wdt_ping,
  87         .set_timeout    = omnia_wdt_set_timeout,
  88         .get_timeleft   = omnia_wdt_get_timeleft,
  89 };
  90
  91 int omnia_mcu_register_watchdog(struct omnia_mcu *mcu)
  92 {
  93         struct device *dev = &mcu->client->dev;
  94         u8 state;
  95         int err;
  96
  97         if (!(mcu->features & OMNIA_FEAT_WDT_PING))
  98                 return 0;
  99
 100         mcu->wdt.info = &omnia_wdt_info;
 101         mcu->wdt.ops = &omnia_wdt_ops;
 102         mcu->wdt.parent = dev;
 103         mcu->wdt.min_timeout = 1;
 104         mcu->wdt.max_timeout = 65535 / DECI;
 105
 106         mcu->wdt.timeout = WATCHDOG_TIMEOUT;
 107         watchdog_init_timeout(&mcu->wdt, timeout, dev);
 108
 109         watchdog_set_drvdata(&mcu->wdt, mcu);
 110
 111         omnia_wdt_set_timeout(&mcu->wdt, mcu->wdt.timeout);
 112
 113         err = omnia_cmd_read_u8(mcu->client, OMNIA_CMD_GET_WATCHDOG_STATE,
 114                                 &state);
 115         if (err)
 116                 return dev_err_probe(dev, err,
 117                                      "Cannot get MCU watchdog state\n");
 118
 119         if (state)
 120                 set_bit(WDOG_HW_RUNNING, &mcu->wdt.status);
 121
 122         watchdog_set_nowayout(&mcu->wdt, nowayout);
 123         watchdog_stop_on_reboot(&mcu->wdt);
 124         err = devm_watchdog_register_device(dev, &mcu->wdt);
 125         if (err)
 126                 return dev_err_probe(dev, err,
 127                                      "Cannot register MCU watchdog\n");
 128
 129         return 0;
 130 }