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i2c: Document reserved I2C addresses

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

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Hans Verkuil <hverkuil@xs4all.nl>
This commit is contained in:
Jean Delvare 2010-06-03 11:33:53 +02:00
parent 3a89db5f30
commit 656b8761ab
1 changed files with 25 additions and 3 deletions
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28
drivers/i2c/i2c-core.c
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@ -387,6 +387,27 @@ static int i2c_check_client_addr_validity(const struct i2c_client *client)
return 0; 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 * i2c_new_device - instantiate an i2c device
* @adap: the adapter managing the device * @adap: the adapter managing the device
@ -1340,10 +1361,11 @@ static int i2c_detect_address(struct i2c_client *temp_client,
int err; int err;
/* Make sure the address is valid */ /* 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", dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",
addr); addr);
return -EINVAL; return err;
} }
/* Skip if already in use */ /* 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++) { for (i = 0; addr_list[i] != I2C_CLIENT_END; i++) {
/* Check address validity */ /* 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 " dev_warn(&adap->dev, "Invalid 7-bit address "
"0x%02x\n", addr_list[i]); "0x%02x\n", addr_list[i]);
continue; continue;