From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean Delvare Subject: [PATCH 3/4] i2c: Document reserved I2C addresses Date: Fri, 9 Apr 2010 16:54:24 +0200 Message-ID: <20100409165424.28d4b1df@hyperion.delvare> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Linux I2C Cc: Hans Verkuil List-Id: linux-i2c@vger.kernel.org Move strict I2C address validity check to a single function, and document the reserved I2C addresses there. Signed-off-by: Jean Delvare Cc: Hans Verkuil --- drivers/i2c/i2c-core.c | 28 +++++++++++++++++++++++++--- 1 file changed, 25 insertions(+), 3 deletions(-) --- linux-2.6.34-rc3.orig/drivers/i2c/i2c-core.c 2010-04-08 13:52:42.000000000 +0200 +++ linux-2.6.34-rc3/drivers/i2c/i2c-core.c 2010-04-08 14:20:32.000000000 +0200 @@ -388,6 +388,27 @@ static int i2c_check_client_addr_validit 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 @@ -1335,10 +1356,11 @@ static int i2c_detect_address(struct i2c 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 */ @@ -1452,7 +1474,7 @@ i2c_new_probed_device(struct i2c_adapter 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; -- Jean Delvare