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i2c: Add i2c_new_probed_device()

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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: Jean Delvare <khali@linux-fr.org>
This commit is contained in:
Jean Delvare 2007-05-01 23:26:31 +02:00 committed by Jean Delvare
parent 0f3b483852
commit 12b5053ac5
2 changed files with 72 additions and 0 deletions
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63
drivers/i2c/i2c-core.c
View File

@ -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;

9
include/linux/i2c.h
View File

@ -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.