[ 3.5.y.z extended stable ] Patch "hwmon: (adm1021) Strengthen chip detection for ADM1021, LM84" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    hwmon: (adm1021) Strengthen chip detection for ADM1021, LM84

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 6a167be97e64721ea9ea1d4f39fea2a79f91654b Mon Sep 17 00:00:00 2001
From: Guenter Roeck <linux at roeck-us.net>
Date: Wed, 5 Jun 2013 14:09:30 -0700
Subject: [PATCH] hwmon: (adm1021) Strengthen chip detection for ADM1021, LM84
 and MAX1617

commit 591bfcfc334a003ba31c0deff03b22e73349939b upstream.

On a system with both MAX1617 and JC42 sensors, JC42 sensors can be misdetected
as LM84. Strengthen detection sufficiently enough to avoid this misdetection.
Also improve detection for ADM1021.

Modeled after chip detection code in sensors-detect command.

Signed-off-by: Guenter Roeck <linux at roeck-us.net>
Tested-by: Jean Delvare <khali at linux-fr.org>
Acked-by: Jean Delvare <khali at linux-fr.org>
[ luis: backport to 3.5: adjust context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/hwmon/adm1021.c | 58 ++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 50 insertions(+), 8 deletions(-)

diff --git a/drivers/hwmon/adm1021.c b/drivers/hwmon/adm1021.c
index 4394e7e..5653461 100644
--- a/drivers/hwmon/adm1021.c
+++ b/drivers/hwmon/adm1021.c
@@ -332,26 +332,68 @@ static int adm1021_detect(struct i2c_client *client,
 	man_id = i2c_smbus_read_byte_data(client, ADM1021_REG_MAN_ID);
 	dev_id = i2c_smbus_read_byte_data(client, ADM1021_REG_DEV_ID);

+	if (man_id < 0 || dev_id < 0)
+		return -ENODEV;
+
 	if (man_id == 0x4d && dev_id == 0x01)
 		type_name = "max1617a";
 	else if (man_id == 0x41) {
 		if ((dev_id & 0xF0) == 0x30)
 			type_name = "adm1023";
-		else
+		else if ((dev_id & 0xF0) == 0x00)
 			type_name = "adm1021";
+		else
+			return -ENODEV;
 	} else if (man_id == 0x49)
 		type_name = "thmc10";
 	else if (man_id == 0x23)
 		type_name = "gl523sm";
 	else if (man_id == 0x54)
 		type_name = "mc1066";
-	/* LM84 Mfr ID in a different place, and it has more unused bits */
-	else if (conv_rate == 0x00
-		 && (config & 0x7F) == 0x00
-		 && (status & 0xAB) == 0x00)
-		type_name = "lm84";
-	else
-		type_name = "max1617";
+	else {
+		int lte, rte, lhi, rhi, llo, rlo;
+
+		/* extra checks for LM84 and MAX1617 to avoid misdetections */
+
+		llo = i2c_smbus_read_byte_data(client, ADM1021_REG_THYST_R(0));
+		rlo = i2c_smbus_read_byte_data(client, ADM1021_REG_THYST_R(1));
+
+		/* fail if any of the additional register reads failed */
+		if (llo < 0 || rlo < 0)
+			return -ENODEV;
+
+		lte = i2c_smbus_read_byte_data(client, ADM1021_REG_TEMP(0));
+		rte = i2c_smbus_read_byte_data(client, ADM1021_REG_TEMP(1));
+		lhi = i2c_smbus_read_byte_data(client, ADM1021_REG_TOS_R(0));
+		rhi = i2c_smbus_read_byte_data(client, ADM1021_REG_TOS_R(1));
+
+		/*
+		 * Fail for negative temperatures and negative high limits.
+		 * This check also catches read errors on the tested registers.
+		 */
+		if ((s8)lte < 0 || (s8)rte < 0 || (s8)lhi < 0 || (s8)rhi < 0)
+			return -ENODEV;
+
+		/* fail if all registers hold the same value */
+		if (lte == rte && lte == lhi && lte == rhi && lte == llo
+		    && lte == rlo)
+			return -ENODEV;
+
+		/*
+		 * LM84 Mfr ID is in a different place,
+		 * and it has more unused bits.
+		 */
+		if (conv_rate == 0x00
+		    && (config & 0x7F) == 0x00
+		    && (status & 0xAB) == 0x00) {
+			type_name = "lm84";
+		} else {
+			/* fail if low limits are larger than high limits */
+			if ((s8)llo > lhi || (s8)rlo > rhi)
+				return -ENODEV;
+			type_name = "max1617";
+		}
+	}

 	pr_debug("adm1021: Detected chip %s at adapter %d, address 0x%02x.\n",
 		 type_name, i2c_adapter_id(adapter), client->addr);
--
1.8.1.2