Commit 656b8761 authored by Jean Delvare's avatar Jean Delvare
Browse files

i2c: Document reserved I2C addresses 



Move strict I2C address validity check to a single function, and
document the reserved I2C addresses there.

Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
Cc: Hans Verkuil <hverkuil@xs4all.nl>
parent 3a89db5f

drivers/i2c/i2c-core.c

+25 −3
Original line number Diff line number Diff line
@@ -387,6 +387,27 @@ static int i2c_check_client_addr_validity(const struct i2c_client *client) 
	return 0;

}



/* And this is a strict address validity check, used when probing. If a

 * device uses a reserved address, then it shouldn't be probed. 7-bit

 * addressing is assumed, 10-bit address devices are rare and should be

 * explicitly enumerated. */

static int i2c_check_addr_validity(unsigned short addr)

{

	/*

	 * Reserved addresses per I2C specification:

	 *  0x00       General call address / START byte

	 *  0x01       CBUS address

	 *  0x02       Reserved for different bus format

	 *  0x03       Reserved for future purposes

	 *  0x04-0x07  Hs-mode master code

	 *  0x78-0x7b  10-bit slave addressing

	 *  0x7c-0x7f  Reserved for future purposes

	 */

	if (addr < 0x08 || addr > 0x77)

		return -EINVAL;

	return 0;

}



/**

 * i2c_new_device - instantiate an i2c device

 * @adap: the adapter managing the device
@@ -1340,10 +1361,11 @@ static int i2c_detect_address(struct i2c_client *temp_client, 
	int err;



	/* Make sure the address is valid */

	if (addr < 0x03 || addr > 0x77) {

	err = i2c_check_addr_validity(addr);

	if (err) {

		dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",

			 addr);

		return -EINVAL;

		return err;

	}



	/* Skip if already in use */
@@ -1446,7 +1468,7 @@ i2c_new_probed_device(struct i2c_adapter *adap, 


	for (i = 0; addr_list[i] != I2C_CLIENT_END; i++) {

		/* Check address validity */

		if (addr_list[i] < 0x03 || addr_list[i] > 0x77) {

		if (i2c_check_addr_validity(addr_list[i]) < 0) {

			dev_warn(&adap->dev, "Invalid 7-bit address "

				 "0x%02x\n", addr_list[i]);

			continue;