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i2c: add register access API

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Add API for reading, writing and updating internal registers of I2C
devices. This API is meant to be used as a simpler way of communicating
with I2C devices that have 8-bit internal registers.

Change-Id: I7280eb530039aa10ad9cc19c1c309c7a2f473eb4
Signed-off-by: Bogdan Davidoaia <bogdan.m.davidoaia@intel.com>
This commit is contained in:
Bogdan Davidoaia 2016-04-21 11:45:36 +03:00 • committed by Anas Nashif
commit ef26bf7848
1 changed files with 145 additions and 0 deletions
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145
include/i2c.h
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@ -238,6 +238,151 @@ static inline int i2c_transfer(struct device *dev,
return api->transfer(dev, msgs, num_msgs, addr);
}
/**
* @brief Read multiple bytes from an internal address of an I2C device.
*
* This routine reads multiple bytes from an internal address of an
* I2C device synchronously.
*
* @param dev Pointer to the device structure for the driver instance.
* @param dev_addr Address of the I2C device for reading.
* @param start_addr Internal address from which the data is being read.
* @param buf Memory pool that stores the retrieved data.
* @param num_bytes Number of bytes being read.
*
* @retval 0 If successful.
* @retval Negative errno code if failure.
*/
static inline int i2c_burst_read(struct device *dev, uint16_t dev_addr,
uint8_t start_addr, uint8_t *buf,
uint8_t num_bytes)
{
struct i2c_driver_api *api;
struct i2c_msg msg[2];
msg[0].buf = &start_addr;
msg[0].len = 1;
msg[0].flags = I2C_MSG_WRITE | I2C_MSG_RESTART;
msg[1].buf = buf;
msg[1].len = num_bytes;
msg[1].flags = I2C_MSG_READ | I2C_MSG_STOP;
api = (struct i2c_driver_api *)dev->driver_api;
return api->transfer(dev, msg, 2, dev_addr);
}
/**
* @brief Write multiple bytes to an internal address of an I2C device.
*
* This routine writes multiple bytes to an internal address of an
* I2C device synchronously.
*
* @param dev Pointer to the device structure for the driver instance.
* @param dev_addr Address of the I2C device for writing.
* @param start_addr Internal address to which the data is being written.
* @param buf Memory pool from which the data is transferred.
* @param num_bytes Number of bytes being written.
*
* @retval 0 If successful.
* @retval Negative errno code if failure.
*/
static inline int i2c_burst_write(struct device *dev, uint16_t dev_addr,
uint8_t start_addr, uint8_t *buf,
uint8_t num_bytes)
{
struct i2c_driver_api *api;
struct i2c_msg msg[2];
msg[0].buf = &start_addr;
msg[0].len = 1;
msg[0].flags = I2C_MSG_WRITE;
msg[1].buf = buf;
msg[1].len = num_bytes;
msg[1].flags = I2C_MSG_WRITE | I2C_MSG_STOP;
api = (struct i2c_driver_api *)dev->driver_api;
return api->transfer(dev, msg, 2, dev_addr);
}
/**
* @brief Read internal register of an I2C device.
*
* This routine reads the value of an 8-bit internal register of an I2C
* device synchronously.
*
* @param dev Pointer to the device structure for the driver instance.
* @param dev_addr Address of the I2C device for reading.
* @param reg_addr Address of the internal register being read.
* @param value Memory pool that stores the retrieved register value.
*
* @retval 0 If successful.
* @retval Negative errno code if failure.
*/
static inline int i2c_reg_read_byte(struct device *dev, uint16_t dev_addr,
uint8_t reg_addr, uint8_t *value)
{
return i2c_burst_read(dev, dev_addr, reg_addr, value, 1);
}
/**
* @brief Write internal register of an I2C device.
*
* This routine writes a value to an 8-bit internal register of an I2C
* device synchronously.
*
* @param dev Pointer to the device structure for the driver instance.
* @param dev_addr Address of the I2C device for writing.
* @param reg_addr Address of the internal register being written.
* @param value Value to be written to internal register.
*
* @retval 0 If successful.
* @retval Negative errno code if failure.
*/
static inline int i2c_reg_write_byte(struct device *dev, uint16_t dev_addr,
uint8_t reg_addr, uint8_t value)
{
uint8_t tx_buf[2] = {reg_addr, value};
return i2c_write(dev, tx_buf, 2, dev_addr);
}
/**
* @brief Update internal register of an I2C device.
*
* This routine updates the value of a set of bits from an 8-bit internal
* register of an I2C device synchronously.
*
* @param dev Pointer to the device structure for the driver instance.
* @param dev_addr Address of the I2C device for updating.
* @param reg_addr Address of the internal register being updated.
* @param value Value for updating internal register.
* @param mask Bitmask for updating internal register.
*
* @retval 0 If successful.
* @retval Negative errno code if failure.
*/
static inline int i2c_reg_update_byte(struct device *dev, uint8_t dev_addr,
uint8_t reg_addr, uint8_t value,
uint8_t mask)
{
uint8_t old_value, new_value;
int rc;
rc = i2c_reg_read_byte(dev, reg_addr, dev_addr, &old_value);
if (rc != 0) {
return rc;
}
new_value = (old_value & ~mask) | (value & mask);
if (new_value == old_value) {
return 0;
}
return i2c_reg_write_byte(dev, dev_addr, reg_addr, new_value);
}
/**
* @brief Suspend an I2C driver.
* @param dev Pointer to the device structure for the driver instance.