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bq769x0: Refactor read functions and fix CRC calculation #55

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merged 1 commit into from
Feb 21, 2024
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bq769x0: Refactor read functions and fix CRC calculation #55

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99 changes: 36 additions & 63 deletions drivers/bms_ic/bq769x0/bq769x0.c
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Original file line number Diff line number Diff line change
Expand Up @@ -100,7 +100,7 @@ static void bq769x0_alert_isr(const struct device *port, struct gpio_callback *c
k_work_schedule(&data->alert_work, K_NO_WAIT);
}

int bq769x0_write_byte(const struct device *dev, uint8_t reg_addr, uint8_t data)
static int bq769x0_write_byte(const struct device *dev, uint8_t reg_addr, uint8_t data)
{
const struct bms_ic_bq769x0_config *dev_config = dev->config;
const struct bms_ic_bq769x0_data *dev_data = dev->data;
Expand All @@ -120,94 +120,67 @@ int bq769x0_write_byte(const struct device *dev, uint8_t reg_addr, uint8_t data)
}
}

int bq769x0_read_byte(const struct device *dev, uint8_t reg_addr, uint8_t *byte)
static int bq769x0_read_bytes(const struct device *dev, uint8_t reg_addr, uint8_t *data,
size_t num_bytes)
{
const struct bms_ic_bq769x0_config *dev_config = dev->config;
const struct bms_ic_bq769x0_data *dev_data = dev->data;
uint8_t buf[3];
uint8_t buf[5] = {
(dev_config->i2c.addr << 1) | 1U, /* target address for CRC calculation */
};
int err;

err = i2c_write_dt(&dev_config->i2c, &reg_addr, 1);
if (err != 0) {
return err;
if (num_bytes < 1 || num_bytes > 2) {
return -EINVAL;
}

if (dev_data->crc_enabled) {
/* CRC is calculated over the slave address (incl. R/W bit) and data */
buf[0] = (dev_config->i2c.addr << 1) | 1U;
int attempts = 1;
while (true) {
err = i2c_read_dt(&dev_config->i2c, buf + 1, 2);
for (int attempts = 1; attempts <= BQ769X0_READ_MAX_ATTEMPTS; attempts++) {
err = i2c_write_read_dt(&dev_config->i2c, &reg_addr, 1, buf + 1, num_bytes * 2);
if (err != 0) {
return err;
}
else if (crc8_ccitt(0, buf, 2) == buf[2]) {
break;
}
else if (attempts >= BQ769X0_READ_MAX_ATTEMPTS) {
LOG_ERR("Failed to read data at 0x%02X after %d attempts", reg_addr,
BQ769X0_READ_MAX_ATTEMPTS);
return -EIO;
}
else {
/* try again */
attempts++;

/*
* First CRC includes target address (incl. R/W bit) and data byte, subsequent CRCs
* only consider data.
*/
if (crc8_ccitt(0, buf, 2) == buf[2]) {
data[0] = buf[1];
if (num_bytes == 1) {
return 0;
}
else if (crc8_ccitt(0, buf + 3, 1) == buf[4]) {
data[1] = buf[3];
return 0;
}
}
}

*byte = buf[1];
LOG_ERR("Failed to read 0x%02X after %d attempts", reg_addr, BQ769X0_READ_MAX_ATTEMPTS);
return -EIO;
}
else {
err = i2c_read_dt(&dev_config->i2c, buf, 1);
if (err != 0) {
return err;
}

*byte = buf[0];
return i2c_write_read_dt(&dev_config->i2c, &reg_addr, 1, data, num_bytes);
}
}

return 0;
static inline int bq769x0_read_byte(const struct device *dev, uint8_t reg_addr, uint8_t *byte)
{
return bq769x0_read_bytes(dev, reg_addr, byte, sizeof(uint8_t));
}

int bq769x0_read_word(const struct device *dev, uint8_t reg_addr, uint16_t *word)
static inline int bq769x0_read_word(const struct device *dev, uint8_t reg_addr, uint16_t *word)
{
const struct bms_ic_bq769x0_config *dev_config = dev->config;
const struct bms_ic_bq769x0_data *dev_data = dev->data;
uint8_t buf[5];
uint8_t buf[2];
int err;

/* write starting register */
i2c_write_dt(&dev_config->i2c, &reg_addr, 1);

if (dev_data->crc_enabled) {
/* CRC is calculated over the slave address (incl. R/W bit) and data */
buf[0] = (dev_config->i2c.addr << 1) | 1U;
err = i2c_read_dt(&dev_config->i2c, buf + 1, 4);
if (err != 0) {
return err;
}

if (crc8_ccitt(0, buf, 2) != buf[2]) {
return -EIO;
}

/* CRC of subsequent bytes only considering data */
if (crc8_ccitt(0, buf + 3, 1) != buf[4]) {
return -EIO;
}

*word = buf[1] << 8 | buf[3];
}
else {
err = i2c_read_dt(&dev_config->i2c, buf, 2);
if (err != 0) {
return err;
}

err = bq769x0_read_bytes(dev, reg_addr, buf, sizeof(buf));
if (err == 0) {
*word = buf[0] << 8 | buf[1];
}

return 0;
return err;
}

static int bq769x0_detect_crc(const struct device *dev)
Expand Down
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