lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Thu, 23 Jun 2016 17:28:27 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Jean Delvare <jdelvare@...e.com>
Cc:	Nishanth Menon <nm@...com>, linux-hwmon@...r.kernel.org,
	linux-kernel@...r.kernel.org, Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH 4/5] hwmon: (tmp102) Rework chip configuration

So far the chip was forced into polarity 0, even if it was preconfigured
differently. Do not touch the polarity when configuring the chip.

Also, the configuration register was read beack to check if the
configuration 'sticks'. Ultimately, that is similar to checking if the
chip is a tmp102 in the first place. Checking if a write into the
configuration register was successful is really not the way to do it,
and quite risky if the chip is not a tmp102, so drop that check.
Instead, verify if the configuration register has unexpected bits set
before writing into it.

Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
 drivers/hwmon/tmp102.c | 37 ++++++++++++++++++++++---------------
 1 file changed, 22 insertions(+), 15 deletions(-)

diff --git a/drivers/hwmon/tmp102.c b/drivers/hwmon/tmp102.c
index 615f9c176aaf..487b4ef5992c 100644
--- a/drivers/hwmon/tmp102.c
+++ b/drivers/hwmon/tmp102.c
@@ -47,6 +47,17 @@
 #define	TMP102_TLOW_REG			0x02
 #define	TMP102_THIGH_REG		0x03
 
+#define TMP102_CONFREG_MASK	(TMP102_CONF_SD | TMP102_CONF_TM | \
+				 TMP102_CONF_POL | TMP102_CONF_F0 | \
+				 TMP102_CONF_F1 | TMP102_CONF_OS | \
+				 TMP102_CONF_EM | TMP102_CONF_AL | \
+				 TMP102_CONF_CR0 | TMP102_CONF_CR1)
+
+#define TMP102_CONFIG_CLEAR	(TMP102_CONF_SD | TMP102_CONF_OS | \
+				 TMP102_CONF_CR0)
+#define TMP102_CONFIG_SET	(TMP102_CONF_TM | TMP102_CONF_EM | \
+				 TMP102_CONF_CR1)
+
 #define CONVERSION_TIME_MS		35	/* in milli-seconds */
 
 struct tmp102 {
@@ -163,9 +174,6 @@ static struct attribute *tmp102_attrs[] = {
 };
 ATTRIBUTE_GROUPS(tmp102);
 
-#define TMP102_CONFIG  (TMP102_CONF_TM | TMP102_CONF_EM | TMP102_CONF_CR1)
-#define TMP102_CONFIG_RD_ONLY (TMP102_CONF_R0 | TMP102_CONF_R1 | TMP102_CONF_AL)
-
 static const struct thermal_zone_of_device_ops tmp102_of_thermal_ops = {
 	.get_temp = tmp102_read_temp,
 };
@@ -206,26 +214,25 @@ static int tmp102_probe(struct i2c_client *client,
 		dev_err(dev, "error reading config register\n");
 		return status;
 	}
+
+	if ((status & ~TMP102_CONFREG_MASK) !=
+	    (TMP102_CONF_R0 | TMP102_CONF_R1)) {
+		dev_err(dev, "unexpected config register value\n");
+		return -ENODEV;
+	}
+
 	tmp102->config_orig = status;
 
 	devm_add_action(dev, tmp102_restore_config, tmp102);
 
-	status = i2c_smbus_write_word_swapped(client, TMP102_CONF_REG,
-					      TMP102_CONFIG);
+	status &= ~TMP102_CONFIG_CLEAR;
+	status |= TMP102_CONFIG_SET;
+
+	status = i2c_smbus_write_word_swapped(client, TMP102_CONF_REG, status);
 	if (status < 0) {
 		dev_err(dev, "error writing config register\n");
 		return status;
 	}
-	status = i2c_smbus_read_word_swapped(client, TMP102_CONF_REG);
-	if (status < 0) {
-		dev_err(dev, "error reading config register\n");
-		return status;
-	}
-	status &= ~TMP102_CONFIG_RD_ONLY;
-	if (status != TMP102_CONFIG) {
-		dev_err(dev, "config settings did not stick\n");
-		return -ENODEV;
-	}
 
 	mutex_init(&tmp102->lock);
 
-- 
2.5.0

Powered by blists - more mailing lists