linux-imx

// SPDX-License-Identifier: GPL-2.0+

/*

 * Raspberry Pi voltage sensor driver

 *

 * Based on firmware/raspberrypi.c by Noralf Trønnes

 *

 * Copyright (C) 2018 Stefan Wahren <stefan.wahren@i2se.com>

 */

#include <linux/device.h>

#include <linux/err.h>

#include <linux/hwmon.h>

#include <linux/module.h>

#include <linux/platform_device.h>

#include <linux/slab.h>

#include <linux/workqueue.h>

#include <soc/bcm2835/raspberrypi-firmware.h>

​

#define UNDERVOLTAGE_STICKY_BIT BIT(16)

​

struct rpi_hwmon_data {

    struct device *hwmon_dev;

    struct rpi_firmware *fw;

    u32 last_throttled;

    struct delayed_work get_values_poll_work;

};

​

static void rpi_firmware_get_throttled(struct rpi_hwmon_data *data)

{

    u32 new_uv, old_uv, value;

    int ret;

​

    /* Request firmware to clear sticky bits */

    value = 0xffff;

​

    ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_THROTTLED,

                    &value, sizeof(value));

    if (ret) {

        dev_err_once(data->hwmon_dev, "Failed to get throttled (%d)\n",

                 ret);

        return;

    }

​

    new_uv = value & UNDERVOLTAGE_STICKY_BIT;

    old_uv = data->last_throttled & UNDERVOLTAGE_STICKY_BIT;

    data->last_throttled = value;

​

    if (new_uv == old_uv)

        return;

​

    if (new_uv)

        dev_crit(data->hwmon_dev, "Undervoltage detected!\n");

    else

        dev_info(data->hwmon_dev, "Voltage normalised\n");

​

    sysfs_notify(&data->hwmon_dev->kobj, NULL, "in0_lcrit_alarm");

}

​

static void get_values_poll(struct work_struct *work)

{

    struct rpi_hwmon_data *data;

​

    data = container_of(work, struct rpi_hwmon_data,

                get_values_poll_work.work);