linux-imx

/* Lantiq cpu temperature sensor driver

 *

 * Copyright (C) 2017 Florian Eckert <fe@dev.tdt.de>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version

 *

 * This program is distributed in the hope that it will be useful

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, see <http://www.gnu.org/licenses/>

 */

​

#include <linux/bitops.h>

#include <linux/delay.h>

#include <linux/hwmon.h>

#include <linux/hwmon-sysfs.h>

#include <linux/init.h>

#include <linux/module.h>

#include <linux/of_device.h>

​

#include <lantiq_soc.h>

​

/* gphy1 configuration register contains cpu temperature */

#define CGU_GPHY1_CR   0x0040

#define CGU_TEMP_PD    BIT(19)

​

static void ltq_cputemp_enable(void)

{

    ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) | CGU_TEMP_PD, CGU_GPHY1_CR);

}

​

static void ltq_cputemp_disable(void *data)

{

    ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) & ~CGU_TEMP_PD, CGU_GPHY1_CR);

}

​

static int ltq_read(struct device *dev, enum hwmon_sensor_types type,

            u32 attr, int channel, long *temp)

{

    int value;

​

    switch (attr) {

    case hwmon_temp_input:

        /* get the temperature including one decimal place */

        value = (ltq_cgu_r32(CGU_GPHY1_CR) >> 9) & 0x01FF;

        value = value * 5;

        /* range -38 to +154 °C, register value zero is -38.0 °C */

        value -= 380;

        /* scale temp to millidegree */

        value = value * 100;

        break;

    default:

        return -EOPNOTSUPP;

    }

​

    *temp = value;

    return 0;