Commit 12b5053a authored by Jean Delvare's avatar Jean Delvare Committed by Jean Delvare
Browse files

i2c: Add i2c_new_probed_device() 



Add a new helper function to instantiate an i2c device. It is meant as a
replacement for i2c_new_device() when you don't know for sure at which
address your I2C/SMBus device lives. This happens frequently on TV
adapters for example, you know there is a tuner chip on the bus, but
depending on the exact board model and revision, it can live at different
addresses. So, the new i2c_new_probed_device() function will probe the bus
according to a list of addresses, and as soon as one of these addresses
responds, it will call i2c_new_device() on that one address.

This function will make it possible to port the old i2c drivers to the
new model quickly.

Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
parent 0f3b4838

drivers/i2c/i2c-core.c

+63 −0
Original line number Diff line number Diff line
@@ -1092,6 +1092,69 @@ int i2c_probe(struct i2c_adapter *adapter, 
}

EXPORT_SYMBOL(i2c_probe);



struct i2c_client *

i2c_new_probed_device(struct i2c_adapter *adap,

		      struct i2c_board_info *info,

		      unsigned short const *addr_list)

{

	int i;



	/* Stop here if the bus doesn't support probing */

	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE)) {

		dev_err(&adap->dev, "Probing not supported\n");

		return NULL;

	}



	mutex_lock(&adap->clist_lock);

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

		/* Check address validity */

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

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

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

			continue;

		}



		/* Check address availability */

		if (__i2c_check_addr(adap, addr_list[i])) {

			dev_dbg(&adap->dev, "Address 0x%02x already in "

				"use, not probing\n", addr_list[i]);

			continue;

		}



		/* Test address responsiveness

		   The default probe method is a quick write, but it is known

		   to corrupt the 24RF08 EEPROMs due to a state machine bug,

		   and could also irreversibly write-protect some EEPROMs, so

		   for address ranges 0x30-0x37 and 0x50-0x5f, we use a byte

		   read instead. Also, some bus drivers don't implement

		   quick write, so we fallback to a byte read it that case

		   too. */

		if ((addr_list[i] & ~0x07) == 0x30

		 || (addr_list[i] & ~0x0f) == 0x50

		 || !i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK)) {

			if (i2c_smbus_xfer(adap, addr_list[i], 0,

					   I2C_SMBUS_READ, 0,

					   I2C_SMBUS_BYTE, NULL) >= 0)

				break;

		} else {

			if (i2c_smbus_xfer(adap, addr_list[i], 0,

					   I2C_SMBUS_WRITE, 0,

					   I2C_SMBUS_QUICK, NULL) >= 0)

				break;

		}

	}

	mutex_unlock(&adap->clist_lock);



	if (addr_list[i] == I2C_CLIENT_END) {

		dev_dbg(&adap->dev, "Probing failed, no device found\n");

		return NULL;

	}



	info->addr = addr_list[i];

	return i2c_new_device(adap, info);

}

EXPORT_SYMBOL_GPL(i2c_new_probed_device);



struct i2c_adapter* i2c_get_adapter(int id)

{

	struct i2c_adapter *adapter;

include/linux/i2c.h

+9 −0
Original line number Diff line number Diff line
@@ -245,6 +245,15 @@ struct i2c_board_info { 
extern struct i2c_client *

i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info);



/* If you don't know the exact address of an I2C device, use this variant

 * instead, which can probe for device presence in a list of possible

 * addresses.

 */

extern struct i2c_client *

i2c_new_probed_device(struct i2c_adapter *adap,

		      struct i2c_board_info *info,

		      unsigned short const *addr_list);



extern void i2c_unregister_device(struct i2c_client *);



/* Mainboard arch_initcall() code should register all its I2C devices.

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