🔌 I2C Device Driver Tutorial: Part 5 - Implementing Data Transfer Operations 🔌

In the fifth part of our I2C device driver tutorial series, we'll focus on implementing data transfer operations in our driver. Data transfer operations allow communication between the Linux kernel and the I2C device, enabling the exchange of information such as sensor readings, configuration settings, or control commands. By understanding how to perform data transfers efficiently and reliably, we can develop robust I2C device drivers capable of interacting with a wide range of I2C devices.

Implementing Data Transfer Operations:

Below is an example of how to implement read and write operations in our I2C device driver:

static ssize_t my_i2c_read(struct file file, char buffer, size_t count, loff_t *offset)

{

 struct i2c_msg msgs[2];

 char data[2] = {0}; // Read data buffer

 // Setup I2C read transaction

 msgs[0].addr = my_i2c_client->addr;

 msgs[0].flags = 0; // Write

 msgs[0].len = 1; // Register address size

 msgs[0].buf = data; 

 msgs[1].addr = my_i2c_client->addr;

 msgs[1].flags = I2C_M_RD; // Read

 msgs[1].len = count; // Data length

 msgs[1].buf = buffer; // Read data buffer

 // Perform I2C read transaction

 return i2c_transfer(my_i2c_client->adapter, msgs, 2);

}

static ssize_t my_i2c_write(struct file file, const char buffer, size_t count, loff_t *offset)

{

 struct i2c_msg msg;

 char data[count + 1]; // Write data buffer

 // Copy data to write buffer

 memcpy(data, buffer, count);

 // Setup I2C write transaction

 msg.addr = my_i2c_client->addr;

 msg.flags = 0; // Write

 msg.len = count + 1; // Data length + register address size

 msg.buf = data; 

 // Perform I2C write transaction

 return i2c_transfer(my_i2c_client->adapter, &msg, 1);

}

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Explanation:

- The `my_i2c_read` function performs a read transaction from the I2C device, reading `count` bytes of data into the `buffer`.

- The `my_i2c_write` function performs a write transaction to the I2C device, writing `count` bytes of data from the `buffer`.

- Both functions use the `i2c_transfer` function to perform the actual data transfer operation.

In the next part of the tutorial, we'll further enhance our I2C device driver by adding support for additional features and error handling.

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