Quelle  cgbc_wdt.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Congatec Board Controller watchdog driver
 *
 * Copyright (C) 2024 Bootlin
 * Author: Thomas Richard <thomas.richard@bootlin.com>
 */

#include <linux/build_bug.h>
#include <linux/device.h>
#include <linux/limits.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>

#include <linux/mfd/cgbc.h>

#define CGBC_WDT_CMD_TRIGGER 0x27
#define CGBC_WDT_CMD_INIT 0x28
#define CGBC_WDT_DISABLE 0x00

#define CGBC_WDT_MODE_SINGLE_EVENT 0x02

#define CGBC_WDT_MIN_TIMEOUT 1
#define CGBC_WDT_MAX_TIMEOUT ((U32_MAX >> 8) / 1000)

#define CGBC_WDT_DEFAULT_TIMEOUT 30
#define CGBC_WDT_DEFAULT_PRETIMEOUT 0

enum action {
 ACTION_INT = 0,
 ACTION_SMI,
 ACTION_RESET,
 ACTION_BUTTON,
};

static unsigned int timeout;
module_param(timeout, uint, 0);
MODULE_PARM_DESC(timeout,
   "Watchdog timeout in seconds. (>=0, default="
   __MODULE_STRING(CGBC_WDT_DEFAULT_TIMEOUT) ")");

static unsigned int pretimeout = CGBC_WDT_DEFAULT_PRETIMEOUT;
module_param(pretimeout, uint, 0);
MODULE_PARM_DESC(pretimeout,
   "Watchdog pretimeout in seconds. (>=0, default="
   __MODULE_STRING(CGBC_WDT_DEFAULT_PRETIMEOUT) ")");

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
   "Watchdog cannot be stopped once started (default="
   __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

struct cgbc_wdt_data {
 struct cgbc_device_data *cgbc;
 struct watchdog_device wdd;
};

struct cgbc_wdt_cmd_cfg {
 u8 cmd;
 u8 mode;
 u8 action;
 u8 timeout1[3];
 u8 timeout2[3];
 u8 reserved[3];
 u8 delay[3];
} __packed;

static_assert(sizeof(struct cgbc_wdt_cmd_cfg) == 15);

static int cgbc_wdt_start(struct watchdog_device *wdd)
{
 struct cgbc_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 struct cgbc_device_data *cgbc = wdt_data->cgbc;
 unsigned int timeout1 = (wdd->timeout - wdd->pretimeout) * 1000;
 unsigned int timeout2 = wdd->pretimeout * 1000;
 u8 action;

 struct cgbc_wdt_cmd_cfg cmd_start = {
  .cmd = CGBC_WDT_CMD_INIT,
  .mode = CGBC_WDT_MODE_SINGLE_EVENT,
  .timeout1[0] = (u8)timeout1,
  .timeout1[1] = (u8)(timeout1 >> 8),
  .timeout1[2] = (u8)(timeout1 >> 16),
  .timeout2[0] = (u8)timeout2,
  .timeout2[1] = (u8)(timeout2 >> 8),
  .timeout2[2] = (u8)(timeout2 >> 16),
 };

 if (wdd->pretimeout) {
  action = 2;
  action |= ACTION_SMI << 2;
  action |= ACTION_RESET << 4;
 } else {
  action = 1;
  action |= ACTION_RESET << 2;
 }

 cmd_start.action = action;

 return cgbc_command(cgbc, &cmd_start, sizeof(cmd_start), NULL, 0, NULL);
}

static int cgbc_wdt_stop(struct watchdog_device *wdd)
{
 struct cgbc_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 struct cgbc_device_data *cgbc = wdt_data->cgbc;
 struct cgbc_wdt_cmd_cfg cmd_stop = {
  .cmd = CGBC_WDT_CMD_INIT,
  .mode = CGBC_WDT_DISABLE,
 };

 return cgbc_command(cgbc, &cmd_stop, sizeof(cmd_stop), NULL, 0, NULL);
}

static int cgbc_wdt_keepalive(struct watchdog_device *wdd)
{
 struct cgbc_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 struct cgbc_device_data *cgbc = wdt_data->cgbc;
 u8 cmd_ping = CGBC_WDT_CMD_TRIGGER;

 return cgbc_command(cgbc, &cmd_ping, sizeof(cmd_ping), NULL, 0, NULL);
}

static int cgbc_wdt_set_pretimeout(struct watchdog_device *wdd,
       unsigned int pretimeout)
{
 wdd->pretimeout = pretimeout;

 if (watchdog_active(wdd))
  return cgbc_wdt_start(wdd);

 return 0;
}

static int cgbc_wdt_set_timeout(struct watchdog_device *wdd,
    unsigned int timeout)
{
 if (timeout < wdd->pretimeout)
  wdd->pretimeout = 0;

 wdd->timeout = timeout;

 if (watchdog_active(wdd))
  return cgbc_wdt_start(wdd);

 return 0;
}

static const struct watchdog_info cgbc_wdt_info = {
 .identity = "CGBC Watchdog",
 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
  WDIOF_MAGICCLOSE | WDIOF_PRETIMEOUT
};

static const struct watchdog_ops cgbc_wdt_ops = {
 .owner  = THIS_MODULE,
 .start  = cgbc_wdt_start,
 .stop  = cgbc_wdt_stop,
 .ping  = cgbc_wdt_keepalive,
 .set_timeout = cgbc_wdt_set_timeout,
 .set_pretimeout = cgbc_wdt_set_pretimeout,
};

static int cgbc_wdt_probe(struct platform_device *pdev)
{
 struct cgbc_device_data *cgbc = dev_get_drvdata(pdev->dev.parent);
 struct device *dev = &pdev->dev;
 struct cgbc_wdt_data *wdt_data;
 struct watchdog_device *wdd;

 wdt_data = devm_kzalloc(dev, sizeof(*wdt_data), GFP_KERNEL);
 if (!wdt_data)
  return -ENOMEM;

 wdt_data->cgbc = cgbc;
 wdd = &wdt_data->wdd;
 wdd->parent = dev;

 wdd->info = &cgbc_wdt_info;
 wdd->ops = &cgbc_wdt_ops;
 wdd->max_timeout = CGBC_WDT_MAX_TIMEOUT;
 wdd->min_timeout = CGBC_WDT_MIN_TIMEOUT;

 watchdog_set_drvdata(wdd, wdt_data);
 watchdog_set_nowayout(wdd, nowayout);

 wdd->timeout = CGBC_WDT_DEFAULT_TIMEOUT;
 watchdog_init_timeout(wdd, timeout, dev);
 cgbc_wdt_set_pretimeout(wdd, pretimeout);

 platform_set_drvdata(pdev, wdt_data);
 watchdog_stop_on_reboot(wdd);
 watchdog_stop_on_unregister(wdd);

 return devm_watchdog_register_device(dev, wdd);
}

static struct platform_driver cgbc_wdt_driver = {
 .driver  = {
  .name = "cgbc-wdt",
 },
 .probe  = cgbc_wdt_probe,
};

module_platform_driver(cgbc_wdt_driver);

MODULE_DESCRIPTION("Congatec Board Controller Watchdog Driver");
MODULE_AUTHOR("Thomas Richard ");
MODULE_LICENSE("GPL");