[PATCH 0/5] hwmon: (lm90) Various fixes

[PATCH 0/5] hwmon: (lm90) Various fixes

[Guenter Roeck]

This series of patches fixes various issues found while
experimenting with and improving the lm90 driver. 

----------------------------------------------------------------
Guenter Roeck (5):
      hwmon: (lm90) Fix usage of CONFIG2 register in detect function
      hwmon: (lm90) Prevent integer overflow/underflow in hysteresis calculations
      hwmon: (lm90) Drop critical attribute support for MAX6654
      hwmom: (lm90) Fix citical alarm status for MAX6680/MAX6681
      hwmon: (lm90) Do not report 'busy' status bit as alarm

 drivers/hwmon/lm90.c | 106 ++++++++++++++++++++++++++++++---------------------
 1 file changed, 62 insertions(+), 44 deletions(-)

[PATCH 1/5] hwmon: (lm90) Fix usage of CONFIG2 register in detect function

[Guenter Roeck]

The detect function had a comment "Make compiler happy" when id did not
read the second configuration register. As it turns out, the code was
checking the contents of this register for manufacturer ID 0xA1 (NXP
Semiconductor/Philips), but never actually read the register. So it
wasn't surprising that the compiler complained, and it indeed had a point.
Fix the code to read the register contents for manufacturer ID 0xa1.

At the same time, the code was reading the register for manufacturer ID
0x41 (Analog Devices), but it was not using the results. In effect it was
just checking if reading the register returned an error. That doesn't
really add much if any value, so stop doing that.

Fixes: f90be42fb383 ("hwmon: (lm90) Refactor reading of config2 register")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/hwmon/lm90.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
index 618052c6cdb6..b05d73c4fbe2 100644
--- a/drivers/hwmon/lm90.c
+++ b/drivers/hwmon/lm90.c
@@ -1465,12 +1465,11 @@ static int lm90_detect(struct i2c_client *client,
 	if (man_id < 0 || chip_id < 0 || config1 < 0 || convrate < 0)
 		return -ENODEV;
 
-	if (man_id == 0x01 || man_id == 0x5C || man_id == 0x41) {
+	if (man_id == 0x01 || man_id == 0x5C || man_id == 0xA1) {
 		config2 = i2c_smbus_read_byte_data(client, LM90_REG_R_CONFIG2);
 		if (config2 < 0)
 			return -ENODEV;
-	} else
-		config2 = 0;		/* Make compiler happy */
+	}
 
 	if ((address == 0x4C || address == 0x4D)
 	 && man_id == 0x01) { /* National Semiconductor */
-- 
2.33.0

[PATCH 2/5] hwmon: (lm90) Prevent integer overflow/underflow in hysteresis calculations

[Guenter Roeck]

Commit b50aa49638c7 ("hwmon: (lm90) Prevent integer underflows of
temperature calculations") addressed a number of underflow situations
when writing temperature limits. However, it missed one situation, seen
when an attempt is made to set the hysteresis value to MAX_LONG and the
critical temperature limit is negative.

Use clamp_val() when setting the hysteresis temperature to ensure that
the provided value can never overflow or underflow.

Fixes: b50aa49638c7 ("hwmon: (lm90) Prevent integer underflows of temperature calculations")
Cc: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/hwmon/lm90.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
index b05d73c4fbe2..72969ea83d82 100644
--- a/drivers/hwmon/lm90.c
+++ b/drivers/hwmon/lm90.c
@@ -1160,8 +1160,8 @@ static int lm90_set_temphyst(struct lm90_data *data, long val)
 	else
 		temp = temp_from_s8(data->temp8[LOCAL_CRIT]);
 
-	/* prevent integer underflow */
-	val = max(val, -128000l);
+	/* prevent integer overflow/underflow */
+	val = clamp_val(val, -128000l, 255000l);
 
 	data->temp_hyst = hyst_to_reg(temp - val);
 	err = i2c_smbus_write_byte_data(client, LM90_REG_W_TCRIT_HYST,
-- 
2.33.0

Re: [PATCH 2/5] hwmon: (lm90) Prevent integer overflow/underflow in hysteresis calculations

[Dmitry Osipenko]

10.12.2021 23:01, Guenter Roeck пишет:
> Commit b50aa49638c7 ("hwmon: (lm90) Prevent integer underflows of
> temperature calculations") addressed a number of underflow situations
> when writing temperature limits. However, it missed one situation, seen
> when an attempt is made to set the hysteresis value to MAX_LONG and the
> critical temperature limit is negative.
> 
> Use clamp_val() when setting the hysteresis temperature to ensure that
> the provided value can never overflow or underflow.
> 
> Fixes: b50aa49638c7 ("hwmon: (lm90) Prevent integer underflows of temperature calculations")
> Cc: Dmitry Osipenko <digetx@gmail.com>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> ---
>  drivers/hwmon/lm90.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
> index b05d73c4fbe2..72969ea83d82 100644
> --- a/drivers/hwmon/lm90.c
> +++ b/drivers/hwmon/lm90.c
> @@ -1160,8 +1160,8 @@ static int lm90_set_temphyst(struct lm90_data *data, long val)
>  	else
>  		temp = temp_from_s8(data->temp8[LOCAL_CRIT]);
>  
> -	/* prevent integer underflow */
> -	val = max(val, -128000l);
> +	/* prevent integer overflow/underflow */
> +	val = clamp_val(val, -128000l, 255000l);
>  
>  	data->temp_hyst = hyst_to_reg(temp - val);
>  	err = i2c_smbus_write_byte_data(client, LM90_REG_W_TCRIT_HYST,
> 

Reviewed-by: Dmitry Osipenko <digetx@gmail.com>

[PATCH 3/5] hwmon: (lm90) Drop critical attribute support for MAX6654

[Guenter Roeck]

Tests with a real chip and a closer look into the datasheet show that
MAX6654 does not support CRIT/THERM/OVERTEMP limits, so drop support
of the respective attributes for this chip.

Introduce LM90_HAVE_CRIT flag and use it to instantiate critical limit
attributes to solve the problem.

Cc: Josh Lehan <krellan@google.com>
Fixes: 229d495d8189 ("hwmon: (lm90) Add max6654 support to lm90 driver")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/hwmon/lm90.c | 86 +++++++++++++++++++++++++-------------------
 1 file changed, 49 insertions(+), 37 deletions(-)

diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
index 72969ea83d82..6597d055e09d 100644
--- a/drivers/hwmon/lm90.c
+++ b/drivers/hwmon/lm90.c
@@ -35,13 +35,14 @@
  * explicitly as max6659, or if its address is not 0x4c.
  * These chips lack the remote temperature offset feature.
  *
- * This driver also supports the MAX6654 chip made by Maxim. This chip can
- * be at 9 different addresses, similar to MAX6680/MAX6681. The MAX6654 is
- * otherwise similar to MAX6657/MAX6658/MAX6659. Extended range is available
- * by setting the configuration register accordingly, and is done during
- * initialization. Extended precision is only available at conversion rates
- * of 1 Hz and slower. Note that extended precision is not enabled by
- * default, as this driver initializes all chips to 2 Hz by design.
+ * This driver also supports the MAX6654 chip made by Maxim. This chip can be
+ * at 9 different addresses, similar to MAX6680/MAX6681. The MAX6654 is similar
+ * to MAX6657/MAX6658/MAX6659, but does not support critical temperature
+ * limits. Extended range is available by setting the configuration register
+ * accordingly, and is done during initialization. Extended precision is only
+ * available at conversion rates of 1 Hz and slower. Note that extended
+ * precision is not enabled by default, as this driver initializes all chips
+ * to 2 Hz by design.
  *
  * This driver also supports the MAX6646, MAX6647, MAX6648, MAX6649 and
  * MAX6692 chips made by Maxim.  These are again similar to the LM86,
@@ -188,6 +189,7 @@ enum chips { lm90, adm1032, lm99, lm86, max6657, max6659, adt7461, max6680,
 #define LM90_HAVE_BROKEN_ALERT	(1 << 7) /* Broken alert		*/
 #define LM90_HAVE_EXTENDED_TEMP	(1 << 8) /* extended temperature support*/
 #define LM90_PAUSE_FOR_CONFIG	(1 << 9) /* Pause conversion for config	*/
+#define LM90_HAVE_CRIT		(1 << 10)/* Chip supports CRIT/OVERT register	*/
 
 /* LM90 status */
 #define LM90_STATUS_LTHRM	(1 << 0) /* local THERM limit tripped */
@@ -354,38 +356,43 @@ struct lm90_params {
 static const struct lm90_params lm90_params[] = {
 	[adm1032] = {
 		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT
-		  | LM90_HAVE_BROKEN_ALERT,
+		  | LM90_HAVE_BROKEN_ALERT | LM90_HAVE_CRIT,
 		.alert_alarms = 0x7c,
 		.max_convrate = 10,
 	},
 	[adt7461] = {
 		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT
-		  | LM90_HAVE_BROKEN_ALERT | LM90_HAVE_EXTENDED_TEMP,
+		  | LM90_HAVE_BROKEN_ALERT | LM90_HAVE_EXTENDED_TEMP
+		  | LM90_HAVE_CRIT,
 		.alert_alarms = 0x7c,
 		.max_convrate = 10,
 	},
 	[g781] = {
 		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT
-		  | LM90_HAVE_BROKEN_ALERT,
+		  | LM90_HAVE_BROKEN_ALERT | LM90_HAVE_CRIT,
 		.alert_alarms = 0x7c,
 		.max_convrate = 8,
 	},
 	[lm86] = {
-		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT,
+		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT
+		  | LM90_HAVE_CRIT,
 		.alert_alarms = 0x7b,
 		.max_convrate = 9,
 	},
 	[lm90] = {
-		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT,
+		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT
+		  | LM90_HAVE_CRIT,
 		.alert_alarms = 0x7b,
 		.max_convrate = 9,
 	},
 	[lm99] = {
-		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT,
+		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT
+		  | LM90_HAVE_CRIT,
 		.alert_alarms = 0x7b,
 		.max_convrate = 9,
 	},
 	[max6646] = {
+		.flags = LM90_HAVE_CRIT,
 		.alert_alarms = 0x7c,
 		.max_convrate = 6,
 		.reg_local_ext = MAX6657_REG_R_LOCAL_TEMPL,
@@ -396,50 +403,50 @@ static const struct lm90_params lm90_params[] = {
 		.reg_local_ext = MAX6657_REG_R_LOCAL_TEMPL,
 	},
 	[max6657] = {
-		.flags = LM90_PAUSE_FOR_CONFIG,
+		.flags = LM90_PAUSE_FOR_CONFIG | LM90_HAVE_CRIT,
 		.alert_alarms = 0x7c,
 		.max_convrate = 8,
 		.reg_local_ext = MAX6657_REG_R_LOCAL_TEMPL,
 	},
 	[max6659] = {
-		.flags = LM90_HAVE_EMERGENCY,
+		.flags = LM90_HAVE_EMERGENCY | LM90_HAVE_CRIT,
 		.alert_alarms = 0x7c,
 		.max_convrate = 8,
 		.reg_local_ext = MAX6657_REG_R_LOCAL_TEMPL,
 	},
 	[max6680] = {
-		.flags = LM90_HAVE_OFFSET,
+		.flags = LM90_HAVE_OFFSET | LM90_HAVE_CRIT,
 		.alert_alarms = 0x7c,
 		.max_convrate = 7,
 	},
 	[max6696] = {
 		.flags = LM90_HAVE_EMERGENCY
-		  | LM90_HAVE_EMERGENCY_ALARM | LM90_HAVE_TEMP3,
+		  | LM90_HAVE_EMERGENCY_ALARM | LM90_HAVE_TEMP3 | LM90_HAVE_CRIT,
 		.alert_alarms = 0x1c7c,
 		.max_convrate = 6,
 		.reg_local_ext = MAX6657_REG_R_LOCAL_TEMPL,
 	},
 	[w83l771] = {
-		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT,
+		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT | LM90_HAVE_CRIT,
 		.alert_alarms = 0x7c,
 		.max_convrate = 8,
 	},
 	[sa56004] = {
-		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT,
+		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT | LM90_HAVE_CRIT,
 		.alert_alarms = 0x7b,
 		.max_convrate = 9,
 		.reg_local_ext = SA56004_REG_R_LOCAL_TEMPL,
 	},
 	[tmp451] = {
 		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT
-		  | LM90_HAVE_BROKEN_ALERT | LM90_HAVE_EXTENDED_TEMP,
+		  | LM90_HAVE_BROKEN_ALERT | LM90_HAVE_EXTENDED_TEMP | LM90_HAVE_CRIT,
 		.alert_alarms = 0x7c,
 		.max_convrate = 9,
 		.reg_local_ext = TMP451_REG_R_LOCAL_TEMPL,
 	},
 	[tmp461] = {
 		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT
-		  | LM90_HAVE_BROKEN_ALERT | LM90_HAVE_EXTENDED_TEMP,
+		  | LM90_HAVE_BROKEN_ALERT | LM90_HAVE_EXTENDED_TEMP | LM90_HAVE_CRIT,
 		.alert_alarms = 0x7c,
 		.max_convrate = 9,
 		.reg_local_ext = TMP451_REG_R_LOCAL_TEMPL,
@@ -668,20 +675,22 @@ static int lm90_update_limits(struct device *dev)
 	struct i2c_client *client = data->client;
 	int val;
 
-	val = lm90_read_reg(client, LM90_REG_R_LOCAL_CRIT);
-	if (val < 0)
-		return val;
-	data->temp8[LOCAL_CRIT] = val;
+	if (data->flags & LM90_HAVE_CRIT) {
+		val = lm90_read_reg(client, LM90_REG_R_LOCAL_CRIT);
+		if (val < 0)
+			return val;
+		data->temp8[LOCAL_CRIT] = val;
 
-	val = lm90_read_reg(client, LM90_REG_R_REMOTE_CRIT);
-	if (val < 0)
-		return val;
-	data->temp8[REMOTE_CRIT] = val;
+		val = lm90_read_reg(client, LM90_REG_R_REMOTE_CRIT);
+		if (val < 0)
+			return val;
+		data->temp8[REMOTE_CRIT] = val;
 
-	val = lm90_read_reg(client, LM90_REG_R_TCRIT_HYST);
-	if (val < 0)
-		return val;
-	data->temp_hyst = val;
+		val = lm90_read_reg(client, LM90_REG_R_TCRIT_HYST);
+		if (val < 0)
+			return val;
+		data->temp_hyst = val;
+	}
 
 	val = lm90_read_reg(client, LM90_REG_R_REMOTE_LOWH);
 	if (val < 0)
@@ -1902,11 +1911,14 @@ static int lm90_probe(struct i2c_client *client)
 	info->config = data->channel_config;
 
 	data->channel_config[0] = HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
-		HWMON_T_CRIT | HWMON_T_CRIT_HYST | HWMON_T_MIN_ALARM |
-		HWMON_T_MAX_ALARM | HWMON_T_CRIT_ALARM;
+		HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM;
 	data->channel_config[1] = HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
-		HWMON_T_CRIT | HWMON_T_CRIT_HYST | HWMON_T_MIN_ALARM |
-		HWMON_T_MAX_ALARM | HWMON_T_CRIT_ALARM | HWMON_T_FAULT;
+		HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM | HWMON_T_FAULT;
+
+	if (data->flags & LM90_HAVE_CRIT) {
+		data->channel_config[0] |= HWMON_T_CRIT | HWMON_T_CRIT_ALARM | HWMON_T_CRIT_HYST;
+		data->channel_config[1] |= HWMON_T_CRIT | HWMON_T_CRIT_ALARM | HWMON_T_CRIT_HYST;
+	}
 
 	if (data->flags & LM90_HAVE_OFFSET)
 		data->channel_config[1] |= HWMON_T_OFFSET;
-- 
2.33.0

[PATCH 4/5] hwmom: (lm90) Fix citical alarm status for MAX6680/MAX6681

[Guenter Roeck]

Tests with a real chip and a closer look into the datasheet reveals
that the local and remote critical alarm status bits are swapped for
MAX6680/MAX6681.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/hwmon/lm90.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
index 6597d055e09d..dd8612a9d536 100644
--- a/drivers/hwmon/lm90.c
+++ b/drivers/hwmon/lm90.c
@@ -190,6 +190,7 @@ enum chips { lm90, adm1032, lm99, lm86, max6657, max6659, adt7461, max6680,
 #define LM90_HAVE_EXTENDED_TEMP	(1 << 8) /* extended temperature support*/
 #define LM90_PAUSE_FOR_CONFIG	(1 << 9) /* Pause conversion for config	*/
 #define LM90_HAVE_CRIT		(1 << 10)/* Chip supports CRIT/OVERT register	*/
+#define LM90_HAVE_CRIT_ALRM_SWP	(1 << 11)/* critical alarm bits swapped	*/
 
 /* LM90 status */
 #define LM90_STATUS_LTHRM	(1 << 0) /* local THERM limit tripped */
@@ -415,7 +416,8 @@ static const struct lm90_params lm90_params[] = {
 		.reg_local_ext = MAX6657_REG_R_LOCAL_TEMPL,
 	},
 	[max6680] = {
-		.flags = LM90_HAVE_OFFSET | LM90_HAVE_CRIT,
+		.flags = LM90_HAVE_OFFSET | LM90_HAVE_CRIT
+		  | LM90_HAVE_CRIT_ALRM_SWP,
 		.alert_alarms = 0x7c,
 		.max_convrate = 7,
 	},
@@ -1201,6 +1203,7 @@ static const u8 lm90_temp_emerg_index[3] = {
 static const u8 lm90_min_alarm_bits[3] = { 5, 3, 11 };
 static const u8 lm90_max_alarm_bits[3] = { 6, 4, 12 };
 static const u8 lm90_crit_alarm_bits[3] = { 0, 1, 9 };
+static const u8 lm90_crit_alarm_bits_swapped[3] = { 1, 0, 9 };
 static const u8 lm90_emergency_alarm_bits[3] = { 15, 13, 14 };
 static const u8 lm90_fault_bits[3] = { 0, 2, 10 };
 
@@ -1226,7 +1229,10 @@ static int lm90_temp_read(struct device *dev, u32 attr, int channel, long *val)
 		*val = (data->alarms >> lm90_max_alarm_bits[channel]) & 1;
 		break;
 	case hwmon_temp_crit_alarm:
-		*val = (data->alarms >> lm90_crit_alarm_bits[channel]) & 1;
+		if (data->flags & LM90_HAVE_CRIT_ALRM_SWP)
+			*val = (data->alarms >> lm90_crit_alarm_bits_swapped[channel]) & 1;
+		else
+			*val = (data->alarms >> lm90_crit_alarm_bits[channel]) & 1;
 		break;
 	case hwmon_temp_emergency_alarm:
 		*val = (data->alarms >> lm90_emergency_alarm_bits[channel]) & 1;
-- 
2.33.0

[PATCH 5/5] hwmon: (lm90) Do not report 'busy' status bit as alarm

[Guenter Roeck]

Bit 7 of the status register indicates that the chip is busy
doing a conversion. It does not indicate an alarm status.
Stop reporting it as alarm status bit.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/hwmon/lm90.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
index dd8612a9d536..74019dff2550 100644
--- a/drivers/hwmon/lm90.c
+++ b/drivers/hwmon/lm90.c
@@ -200,6 +200,7 @@ enum chips { lm90, adm1032, lm99, lm86, max6657, max6659, adt7461, max6680,
 #define LM90_STATUS_RHIGH	(1 << 4) /* remote high temp limit tripped */
 #define LM90_STATUS_LLOW	(1 << 5) /* local low temp limit tripped */
 #define LM90_STATUS_LHIGH	(1 << 6) /* local high temp limit tripped */
+#define LM90_STATUS_BUSY	(1 << 7) /* conversion is ongoing */
 
 #define MAX6696_STATUS2_R2THRM	(1 << 1) /* remote2 THERM limit tripped */
 #define MAX6696_STATUS2_R2OPEN	(1 << 2) /* remote2 is an open circuit */
@@ -820,7 +821,7 @@ static int lm90_update_device(struct device *dev)
 		val = lm90_read_reg(client, LM90_REG_R_STATUS);
 		if (val < 0)
 			return val;
-		data->alarms = val;	/* lower 8 bit of alarms */
+		data->alarms = val & ~LM90_STATUS_BUSY;
 
 		if (data->kind == max6696) {
 			val = lm90_select_remote_channel(data, 1);
-- 
2.33.0