linux-imx

// SPDX-License-Identifier: GPL-2.0

/*

 * sht15.c - support for the SHT15 Temperature and Humidity Sensor

 *

 * Portions Copyright (c) 2010-2012 Savoir-faire Linux Inc.

 *          Jerome Oufella <jerome.oufella@savoirfairelinux.com>

 *          Vivien Didelot <vivien.didelot@savoirfairelinux.com>

 *

 * Copyright (c) 2009 Jonathan Cameron

 *

 * Copyright (c) 2007 Wouter Horre

 *

 * For further information, see the Documentation/hwmon/sht15 file.

 */

​

#include <linux/interrupt.h>

#include <linux/irq.h>

#include <linux/module.h>

#include <linux/init.h>

#include <linux/hwmon.h>

#include <linux/hwmon-sysfs.h>

#include <linux/mutex.h>

#include <linux/platform_device.h>

#include <linux/sched.h>

#include <linux/delay.h>

#include <linux/jiffies.h>

#include <linux/err.h>

#include <linux/regulator/consumer.h>

#include <linux/slab.h>

#include <linux/atomic.h>

#include <linux/bitrev.h>

#include <linux/gpio/consumer.h>

#include <linux/of.h>

​

/* Commands */

#define SHT15_MEASURE_TEMP      0x03

#define SHT15_MEASURE_RH        0x05

#define SHT15_WRITE_STATUS      0x06

#define SHT15_READ_STATUS       0x07

#define SHT15_SOFT_RESET        0x1E

​

/* Min timings */

#define SHT15_TSCKL         100 /* (nsecs) clock low */

#define SHT15_TSCKH         100 /* (nsecs) clock high */

#define SHT15_TSU           150 /* (nsecs) data setup time */

#define SHT15_TSRST         11  /* (msecs) soft reset time */

​

/* Status Register Bits */

#define SHT15_STATUS_LOW_RESOLUTION 0x01

#define SHT15_STATUS_NO_OTP_RELOAD  0x02

#define SHT15_STATUS_HEATER     0x04

#define SHT15_STATUS_LOW_BATTERY    0x40

​

/* List of supported chips */

enum sht15_chips { sht10, sht11, sht15, sht71, sht75 };

​

/* Actions the driver may be doing */

enum sht15_state {

    SHT15_READING_NOTHING,

    SHT15_READING_TEMP,

    SHT15_READING_HUMID

};

​

/**

 * struct sht15_temppair - elements of voltage dependent temp calc

 * @vdd:    supply voltage in microvolts

 * @d1:     see data sheet

 */

struct sht15_temppair {

    int vdd; /* microvolts */

    int d1;

};

​

/* Table 9 from datasheet - relates temperature calculation to supply voltage */

static const struct sht15_temppair temppoints[] = {

    { 2500000, -39400 },

    { 3000000, -39600 },

    { 3500000, -39700 },

    { 4000000, -39800 },

    { 5000000, -40100 },

};

​

/* Table from CRC datasheet, section 2.4 */

static const u8 sht15_crc8_table[] = {

    0,  49, 98, 83, 196,    245,    166,    151,

    185,    136,    219,    234,    125,    76, 31, 46,

    67, 114,    33, 16, 135,    182,    229,    212,

    250,    203,    152,    169,    62, 15, 92, 109,

    134,    183,    228,    213,    66, 115,    32, 17,

    63, 14, 93, 108,    251,    202,    153,    168,

    197,    244,    167,    150,    1,  48, 99, 82,

    124,    77, 30, 47, 184,    137,    218,    235,