From 656b8761ab21715eb1a35bb078dfd05e901be4ec Mon Sep 17 00:00:00 2001
From: Jean Delvare <khali@linux-fr.org>
Date: Thu, 3 Jun 2010 11:33:53 +0200
Subject: [PATCH] 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: Jean Delvare <khali@linux-fr.org>
Cc: Hans Verkuil <hverkuil@xs4all.nl>
---
drivers/i2c/i2c-core.c | 28 +++++++++++++++++++++++++---
1 file changed, 25 insertions(+), 3 deletions(-)
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 96f01331544d..af5172486fab 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -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;
--
2.20.1