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linux/drivers/w1/slaves/w1_ds2438.c
Luiz Sampaio c999fbbdcf w1: ds2438: support for writing to offset register 
Added a sysfs entry to support writing to the offset register on page1.
This register is used to calibrate the chip canceling offset errors in the
current ADC. This means that, over time, reading the IAD register will not
return the correct current measurement, it will have an offset. Writing to
the offset register if the two's complement of the current register while
passing zero current to the load will calibrate the measurements. This
change was tested on real hardware and it was able to calibrate the chip
correctly.

Signed-off-by: Luiz Sampaio <sampaio.ime@gmail.com>
Link: https://lore.kernel.org/r/20210519223046.13798-7-sampaio.ime@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-05-21 14:51:33 +02:00

519 lines
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// SPDX-License-Identifier: GPL-2.0-only
/*
* 1-Wire implementation for the ds2438 chip
*
* Copyright (c) 2017 Mariusz Bialonczyk <manio@skyboo.net>
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/types.h>
#include <linux/delay.h>
#include <linux/w1.h>
#define W1_FAMILY_DS2438 0x26
#define W1_DS2438_RETRIES 3
/* Memory commands */
#define W1_DS2438_READ_SCRATCH 0xBE
#define W1_DS2438_WRITE_SCRATCH 0x4E
#define W1_DS2438_COPY_SCRATCH 0x48
#define W1_DS2438_RECALL_MEMORY 0xB8
/* Register commands */
#define W1_DS2438_CONVERT_TEMP 0x44
#define W1_DS2438_CONVERT_VOLTAGE 0xB4
#define DS2438_PAGE_SIZE 8
#define DS2438_ADC_INPUT_VAD 0
#define DS2438_ADC_INPUT_VDD 1
#define DS2438_MAX_CONVERSION_TIME 10 /* ms */
/* Page #0 definitions */
#define DS2438_STATUS_REG 0x00 /* Status/Configuration Register */
#define DS2438_STATUS_IAD (1 << 0) /* Current A/D Control Bit */
#define DS2438_STATUS_CA (1 << 1) /* Current Accumulator Configuration */
#define DS2438_STATUS_EE (1 << 2) /* Current Accumulator Shadow Selector bit */
#define DS2438_STATUS_AD (1 << 3) /* Voltage A/D Input Select Bit */
#define DS2438_STATUS_TB (1 << 4) /* Temperature Busy Flag */
#define DS2438_STATUS_NVB (1 << 5) /* Nonvolatile Memory Busy Flag */
#define DS2438_STATUS_ADB (1 << 6) /* A/D Converter Busy Flag */
#define DS2438_TEMP_LSB 0x01
#define DS2438_TEMP_MSB 0x02
#define DS2438_VOLTAGE_LSB 0x03
#define DS2438_VOLTAGE_MSB 0x04
#define DS2438_CURRENT_LSB 0x05
#define DS2438_CURRENT_MSB 0x06
#define DS2438_THRESHOLD 0x07
/* Page #1 definitions */
#define DS2438_ETM_0 0x00
#define DS2438_ETM_1 0x01
#define DS2438_ETM_2 0x02
#define DS2438_ETM_3 0x03
#define DS2438_ICA 0x04
#define DS2438_OFFSET_LSB 0x05
#define DS2438_OFFSET_MSB 0x06
static int w1_ds2438_get_page(struct w1_slave *sl, int pageno, u8 *buf)
{
unsigned int retries = W1_DS2438_RETRIES;
u8 w1_buf[2];
u8 crc;
size_t count;
while (retries--) {
crc = 0;
if (w1_reset_select_slave(sl))
continue;
w1_buf[0] = W1_DS2438_RECALL_MEMORY;
w1_buf[1] = (u8)pageno;
w1_write_block(sl->master, w1_buf, 2);
if (w1_reset_select_slave(sl))
continue;
w1_buf[0] = W1_DS2438_READ_SCRATCH;
w1_buf[1] = (u8)pageno;
w1_write_block(sl->master, w1_buf, 2);
count = w1_read_block(sl->master, buf, DS2438_PAGE_SIZE + 1);
if (count == DS2438_PAGE_SIZE + 1) {
crc = w1_calc_crc8(buf, DS2438_PAGE_SIZE);
/* check for correct CRC */
if ((u8)buf[DS2438_PAGE_SIZE] == crc)
return 0;
}
}
return -1;
}
static int w1_ds2438_get_temperature(struct w1_slave *sl, int16_t *temperature)
{
unsigned int retries = W1_DS2438_RETRIES;
u8 w1_buf[DS2438_PAGE_SIZE + 1 /*for CRC*/];
unsigned int tm = DS2438_MAX_CONVERSION_TIME;
unsigned long sleep_rem;
int ret;
mutex_lock(&sl->master->bus_mutex);
while (retries--) {
if (w1_reset_select_slave(sl))
continue;
w1_write_8(sl->master, W1_DS2438_CONVERT_TEMP);
mutex_unlock(&sl->master->bus_mutex);
sleep_rem = msleep_interruptible(tm);
if (sleep_rem != 0) {
ret = -1;
goto post_unlock;
}
if (mutex_lock_interruptible(&sl->master->bus_mutex) != 0) {
ret = -1;
goto post_unlock;
}
break;
}
if (w1_ds2438_get_page(sl, 0, w1_buf) == 0) {
*temperature = (((int16_t) w1_buf[DS2438_TEMP_MSB]) << 8) | ((uint16_t) w1_buf[DS2438_TEMP_LSB]);
ret = 0;
} else
ret = -1;
mutex_unlock(&sl->master->bus_mutex);
post_unlock:
return ret;
}
static int w1_ds2438_change_config_bit(struct w1_slave *sl, u8 mask, u8 value)
{
unsigned int retries = W1_DS2438_RETRIES;
u8 w1_buf[3];
u8 status;
int perform_write = 0;
while (retries--) {
if (w1_reset_select_slave(sl))
continue;
w1_buf[0] = W1_DS2438_RECALL_MEMORY;
w1_buf[1] = 0x00;
w1_write_block(sl->master, w1_buf, 2);
if (w1_reset_select_slave(sl))
continue;
w1_buf[0] = W1_DS2438_READ_SCRATCH;
w1_buf[1] = 0x00;
w1_write_block(sl->master, w1_buf, 2);
/* reading one byte of result */
status = w1_read_8(sl->master);
/* if bit0=1, set a value to a mask for easy compare */
if (value)
value = mask;
if ((status & mask) == value)
return 0; /* already set as requested */
/* changing bit */
status ^= mask;
perform_write = 1;
break;
}
if (perform_write) {
retries = W1_DS2438_RETRIES;
while (retries--) {
if (w1_reset_select_slave(sl))
continue;
w1_buf[0] = W1_DS2438_WRITE_SCRATCH;
w1_buf[1] = 0x00;
w1_buf[2] = status;
w1_write_block(sl->master, w1_buf, 3);
if (w1_reset_select_slave(sl))
continue;
w1_buf[0] = W1_DS2438_COPY_SCRATCH;
w1_buf[1] = 0x00;
w1_write_block(sl->master, w1_buf, 2);
return 0;
}
}
return -1;
}
static int w1_ds2438_change_offset_register(struct w1_slave *sl, u8 *value)
{
unsigned int retries = W1_DS2438_RETRIES;
u8 w1_buf[9];
u8 w1_page1_buf[DS2438_PAGE_SIZE + 1 /*for CRC*/];
if (w1_ds2438_get_page(sl, 1, w1_page1_buf) == 0) {
memcpy(&w1_buf[2], w1_page1_buf, DS2438_PAGE_SIZE - 1); /* last register reserved */
w1_buf[7] = value[0]; /* change only offset register */
w1_buf[8] = value[1];
while (retries--) {
if (w1_reset_select_slave(sl))
continue;
w1_buf[0] = W1_DS2438_WRITE_SCRATCH;
w1_buf[1] = 0x01; /* write to page 1 */
w1_write_block(sl->master, w1_buf, 9);
if (w1_reset_select_slave(sl))
continue;
w1_buf[0] = W1_DS2438_COPY_SCRATCH;
w1_buf[1] = 0x01;
w1_write_block(sl->master, w1_buf, 2);
return 0;
}
}
return -1;
}
static int w1_ds2438_get_voltage(struct w1_slave *sl,
int adc_input, uint16_t *voltage)
{
unsigned int retries = W1_DS2438_RETRIES;
u8 w1_buf[DS2438_PAGE_SIZE + 1 /*for CRC*/];
unsigned int tm = DS2438_MAX_CONVERSION_TIME;
unsigned long sleep_rem;
int ret;
mutex_lock(&sl->master->bus_mutex);
if (w1_ds2438_change_config_bit(sl, DS2438_STATUS_AD, adc_input)) {
ret = -1;
goto pre_unlock;
}
while (retries--) {
if (w1_reset_select_slave(sl))
continue;
w1_write_8(sl->master, W1_DS2438_CONVERT_VOLTAGE);
mutex_unlock(&sl->master->bus_mutex);
sleep_rem = msleep_interruptible(tm);
if (sleep_rem != 0) {
ret = -1;
goto post_unlock;
}
if (mutex_lock_interruptible(&sl->master->bus_mutex) != 0) {
ret = -1;
goto post_unlock;
}
break;
}
if (w1_ds2438_get_page(sl, 0, w1_buf) == 0) {
*voltage = (((uint16_t) w1_buf[DS2438_VOLTAGE_MSB]) << 8) | ((uint16_t) w1_buf[DS2438_VOLTAGE_LSB]);
ret = 0;
} else
ret = -1;
pre_unlock:
mutex_unlock(&sl->master->bus_mutex);
post_unlock:
return ret;
}
static int w1_ds2438_get_current(struct w1_slave *sl, int16_t *voltage)
{
u8 w1_buf[DS2438_PAGE_SIZE + 1 /*for CRC*/];
int ret;
mutex_lock(&sl->master->bus_mutex);
if (w1_ds2438_get_page(sl, 0, w1_buf) == 0) {
/* The voltage measured across current sense resistor RSENS. */
*voltage = (((int16_t) w1_buf[DS2438_CURRENT_MSB]) << 8) | ((int16_t) w1_buf[DS2438_CURRENT_LSB]);
ret = 0;
} else
ret = -1;
mutex_unlock(&sl->master->bus_mutex);
return ret;
}
static ssize_t iad_write(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr, char *buf,
loff_t off, size_t count)
{
struct w1_slave *sl = kobj_to_w1_slave(kobj);
int ret;
if (count != 1 || off != 0)
return -EFAULT;
mutex_lock(&sl->master->bus_mutex);
if (w1_ds2438_change_config_bit(sl, DS2438_STATUS_IAD, *buf & 0x01) == 0)
ret = 1;
else
ret = -EIO;
mutex_unlock(&sl->master->bus_mutex);
return ret;
}
static ssize_t iad_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr, char *buf,
loff_t off, size_t count)
{
struct w1_slave *sl = kobj_to_w1_slave(kobj);
int ret;
int16_t voltage;
if (off != 0)
return 0;
if (!buf)
return -EINVAL;
if (w1_ds2438_get_current(sl, &voltage) == 0)
ret = snprintf(buf, count, "%i\n", voltage);
else
ret = -EIO;
return ret;
}
static ssize_t page0_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr, char *buf,
loff_t off, size_t count)
{
struct w1_slave *sl = kobj_to_w1_slave(kobj);
int ret;
u8 w1_buf[DS2438_PAGE_SIZE + 1 /*for CRC*/];
if (off != 0)
return 0;
if (!buf)
return -EINVAL;
mutex_lock(&sl->master->bus_mutex);
/* Read no more than page0 size */
if (count > DS2438_PAGE_SIZE)
count = DS2438_PAGE_SIZE;
if (w1_ds2438_get_page(sl, 0, w1_buf) == 0) {
memcpy(buf, &w1_buf, count);
ret = count;
} else
ret = -EIO;
mutex_unlock(&sl->master->bus_mutex);
return ret;
}
static ssize_t page1_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr, char *buf,
loff_t off, size_t count)
{
struct w1_slave *sl = kobj_to_w1_slave(kobj);
int ret;
u8 w1_buf[DS2438_PAGE_SIZE + 1 /*for CRC*/];
if (off != 0)
return 0;
if (!buf)
return -EINVAL;
mutex_lock(&sl->master->bus_mutex);
/* Read no more than page1 size */
if (count > DS2438_PAGE_SIZE)
count = DS2438_PAGE_SIZE;
if (w1_ds2438_get_page(sl, 1, w1_buf) == 0) {
memcpy(buf, &w1_buf, count);
ret = count;
} else
ret = -EIO;
mutex_unlock(&sl->master->bus_mutex);
return ret;
}
static ssize_t offset_write(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr, char *buf,
loff_t off, size_t count)
{
struct w1_slave *sl = kobj_to_w1_slave(kobj);
int ret;
mutex_lock(&sl->master->bus_mutex);
if (w1_ds2438_change_offset_register(sl, buf) == 0)
ret = count;
else
ret = -EIO;
mutex_unlock(&sl->master->bus_mutex);
return ret;
}
static ssize_t temperature_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr, char *buf,
loff_t off, size_t count)
{
struct w1_slave *sl = kobj_to_w1_slave(kobj);
int ret;
int16_t temp;
if (off != 0)
return 0;
if (!buf)
return -EINVAL;
if (w1_ds2438_get_temperature(sl, &temp) == 0)
ret = snprintf(buf, count, "%i\n", temp);
else
ret = -EIO;
return ret;
}
static ssize_t vad_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr, char *buf,
loff_t off, size_t count)
{
struct w1_slave *sl = kobj_to_w1_slave(kobj);
int ret;
uint16_t voltage;
if (off != 0)
return 0;
if (!buf)
return -EINVAL;
if (w1_ds2438_get_voltage(sl, DS2438_ADC_INPUT_VAD, &voltage) == 0)
ret = snprintf(buf, count, "%u\n", voltage);
else
ret = -EIO;
return ret;
}
static ssize_t vdd_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr, char *buf,
loff_t off, size_t count)
{
struct w1_slave *sl = kobj_to_w1_slave(kobj);
int ret;
uint16_t voltage;
if (off != 0)
return 0;
if (!buf)
return -EINVAL;
if (w1_ds2438_get_voltage(sl, DS2438_ADC_INPUT_VDD, &voltage) == 0)
ret = snprintf(buf, count, "%u\n", voltage);
else
ret = -EIO;
return ret;
}
static BIN_ATTR_RW(iad, 0);
static BIN_ATTR_RO(page0, DS2438_PAGE_SIZE);
static BIN_ATTR_RO(page1, DS2438_PAGE_SIZE);
static BIN_ATTR_WO(offset, 2);
static BIN_ATTR_RO(temperature, 0/* real length varies */);
static BIN_ATTR_RO(vad, 0/* real length varies */);
static BIN_ATTR_RO(vdd, 0/* real length varies */);
static struct bin_attribute *w1_ds2438_bin_attrs[] = {
&bin_attr_iad,
&bin_attr_page0,
&bin_attr_page1,
&bin_attr_offset,
&bin_attr_temperature,
&bin_attr_vad,
&bin_attr_vdd,
NULL,
};
static const struct attribute_group w1_ds2438_group = {
.bin_attrs = w1_ds2438_bin_attrs,
};
static const struct attribute_group *w1_ds2438_groups[] = {
&w1_ds2438_group,
NULL,
};
static const struct w1_family_ops w1_ds2438_fops = {
.groups = w1_ds2438_groups,
};
static struct w1_family w1_ds2438_family = {
.fid = W1_FAMILY_DS2438,
.fops = &w1_ds2438_fops,
};
module_w1_family(w1_ds2438_family);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Mariusz Bialonczyk <manio@skyboo.net>");
MODULE_DESCRIPTION("1-wire driver for Maxim/Dallas DS2438 Smart Battery Monitor");
MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS2438));
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