Quelle  arm_smc_wdt.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-only
/*
 * ARM Secure Monitor Call watchdog driver
 *
 * Copyright 2020 Google LLC.
 * Julius Werner <jwerner@chromium.org>
 * Based on mtk_wdt.c
 */

#include <linux/arm-smccc.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/types.h>
#include <linux/watchdog.h>
#include <uapi/linux/psci.h>

#define DRV_NAME  "arm_smc_wdt"
#define DRV_VERSION  "1.0"

enum smcwd_call {
 SMCWD_INIT  = 0,
 SMCWD_SET_TIMEOUT = 1,
 SMCWD_ENABLE  = 2,
 SMCWD_PET  = 3,
 SMCWD_GET_TIMELEFT = 4,
};

static bool nowayout = WATCHDOG_NOWAYOUT;
static unsigned int timeout;

static int smcwd_call(struct watchdog_device *wdd, enum smcwd_call call,
        unsigned long arg, struct arm_smccc_res *res)
{
 struct arm_smccc_res local_res;

 if (!res)
  res = &local_res;

 arm_smccc_smc((u32)(uintptr_t)watchdog_get_drvdata(wdd), call, arg, 0,
        0, 0, 0, 0, res);

 if (res->a0 == PSCI_RET_NOT_SUPPORTED)
  return -ENODEV;
 if (res->a0 == PSCI_RET_INVALID_PARAMS)
  return -EINVAL;
 if (res->a0 == PSCI_RET_DISABLED)
  return -ENODATA;
 if (res->a0 != PSCI_RET_SUCCESS)
  return -EIO;
 return 0;
}

static int smcwd_ping(struct watchdog_device *wdd)
{
 return smcwd_call(wdd, SMCWD_PET, 0, NULL);
}

static unsigned int smcwd_get_timeleft(struct watchdog_device *wdd)
{
 struct arm_smccc_res res;

 smcwd_call(wdd, SMCWD_GET_TIMELEFT, 0, &res);
 if (res.a0)
  return 0;
 return res.a1;
}

static int smcwd_set_timeout(struct watchdog_device *wdd, unsigned int timeout)
{
 int res;

 res = smcwd_call(wdd, SMCWD_SET_TIMEOUT, timeout, NULL);
 if (!res)
  wdd->timeout = timeout;
 return res;
}

static int smcwd_stop(struct watchdog_device *wdd)
{
 return smcwd_call(wdd, SMCWD_ENABLE, 0, NULL);
}

static int smcwd_start(struct watchdog_device *wdd)
{
 return smcwd_call(wdd, SMCWD_ENABLE, 1, NULL);
}

static const struct watchdog_info smcwd_info = {
 .identity = DRV_NAME,
 .options = WDIOF_SETTIMEOUT |
     WDIOF_KEEPALIVEPING |
     WDIOF_MAGICCLOSE,
};

static const struct watchdog_ops smcwd_ops = {
 .start  = smcwd_start,
 .stop  = smcwd_stop,
 .ping  = smcwd_ping,
 .set_timeout = smcwd_set_timeout,
};

static const struct watchdog_ops smcwd_timeleft_ops = {
 .start  = smcwd_start,
 .stop  = smcwd_stop,
 .ping  = smcwd_ping,
 .set_timeout = smcwd_set_timeout,
 .get_timeleft = smcwd_get_timeleft,
};

static int smcwd_probe(struct platform_device *pdev)
{
 struct watchdog_device *wdd;
 int err;
 struct arm_smccc_res res;
 u32 smc_func_id;

 wdd = devm_kzalloc(&pdev->dev, sizeof(*wdd), GFP_KERNEL);
 if (!wdd)
  return -ENOMEM;
 platform_set_drvdata(pdev, wdd);

 if (of_property_read_u32(pdev->dev.of_node, "arm,smc-id",
     &smc_func_id))
  smc_func_id = 0x82003D06;
 watchdog_set_drvdata(wdd, (void *)(uintptr_t)smc_func_id);

 err = smcwd_call(wdd, SMCWD_INIT, 0, &res);
 if (err < 0)
  return err;

 wdd->info = &smcwd_info;
 /* get_timeleft is optional */
 err = smcwd_call(wdd, SMCWD_GET_TIMELEFT, 0, NULL);
 switch (err) {
 case 0:
  set_bit(WDOG_HW_RUNNING, &wdd->status);
  fallthrough;
 case -ENODATA:
  wdd->ops = &smcwd_timeleft_ops;
  break;
 default:
  wdd->ops = &smcwd_ops;
  break;
 }

 wdd->timeout = res.a2;
 wdd->max_timeout = res.a2;
 wdd->min_timeout = res.a1;
 wdd->parent = &pdev->dev;

 watchdog_stop_on_reboot(wdd);
 watchdog_stop_on_unregister(wdd);
 watchdog_set_nowayout(wdd, nowayout);
 watchdog_init_timeout(wdd, timeout, &pdev->dev);
 err = smcwd_set_timeout(wdd, wdd->timeout);
 if (err)
  return err;

 err = devm_watchdog_register_device(&pdev->dev, wdd);
 if (err)
  return err;

 dev_info(&pdev->dev,
   "Watchdog registered (timeout=%d sec, nowayout=%d)\n",
   wdd->timeout, nowayout);

 return 0;
}

static const struct of_device_id smcwd_dt_ids[] = {
 { .compatible = "arm,smc-wdt" },
 {}
};
MODULE_DEVICE_TABLE(of, smcwd_dt_ids);

static struct platform_driver smcwd_driver = {
 .probe  = smcwd_probe,
 .driver  = {
  .name  = DRV_NAME,
  .of_match_table = smcwd_dt_ids,
 },
};

module_platform_driver(smcwd_driver);

module_param(timeout, uint, 0);
MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");

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

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Julius Werner ");
MODULE_DESCRIPTION("ARM Secure Monitor Call Watchdog Driver");
MODULE_VERSION(DRV_VERSION);