[PATCH AUTOSEL 5.4 36/50] hwmon: (max31790) Report correct current pwm duty cycles

[PATCH AUTOSEL 5.4 36/50] hwmon: (max31790) Report correct current pwm duty cycles

[Sasha Levin]

From: Guenter Roeck <linux@roeck-us.net>

[ Upstream commit 897f6339893b741a5d68ae8e2475df65946041c2 ]

The MAX31790 has two sets of registers for pwm duty cycles, one to request
a duty cycle and one to read the actual current duty cycle. Both do not
have to be the same.

When reporting the pwm duty cycle to the user, the actual pwm duty cycle
from pwm duty cycle registers needs to be reported. When setting it, the
pwm target duty cycle needs to be written. Since we don't know the actual
pwm duty cycle after a target pwm duty cycle has been written, set the
valid flag to false to indicate that actual pwm duty cycle should be read
from the chip instead of using cached values.

Cc: Jan Kundrát <jan.kundrat@cesnet.cz>
Cc: Václav Kubernát <kubernat@cesnet.cz>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Václav Kubernát <kubernat@ceesnet.cz>
Reviewed-by: Jan Kundrát <jan.kundrat@cesnet.cz>
Link: https://lore.kernel.org/r/20210526154022.3223012-3-linux@roeck-us.net
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 Documentation/hwmon/max31790.rst | 3 ++-
 drivers/hwmon/max31790.c         | 6 +++---
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/Documentation/hwmon/max31790.rst b/Documentation/hwmon/max31790.rst
index 84c62a12ef3a..9f12aac4fab5 100644
--- a/Documentation/hwmon/max31790.rst
+++ b/Documentation/hwmon/max31790.rst
@@ -39,5 +39,6 @@ fan[1-12]_input    RO  fan tachometer speed in RPM
 fan[1-12]_fault    RO  fan experienced fault
 fan[1-6]_target    RW  desired fan speed in RPM
 pwm[1-6]_enable    RW  regulator mode, 0=disabled, 1=manual mode, 2=rpm mode
-pwm[1-6]           RW  fan target duty cycle (0-255)
+pwm[1-6]           RW  read: current pwm duty cycle,
+                       write: target pwm duty cycle (0-255)
 ================== === =======================================================
diff --git a/drivers/hwmon/max31790.c b/drivers/hwmon/max31790.c
index 117fb79ef294..344be7829d58 100644
--- a/drivers/hwmon/max31790.c
+++ b/drivers/hwmon/max31790.c
@@ -104,7 +104,7 @@ static struct max31790_data *max31790_update_device(struct device *dev)
 				data->tach[NR_CHANNEL + i] = rv;
 			} else {
 				rv = i2c_smbus_read_word_swapped(client,
-						MAX31790_REG_PWMOUT(i));
+						MAX31790_REG_PWM_DUTY_CYCLE(i));
 				if (rv < 0)
 					goto abort;
 				data->pwm[i] = rv;
@@ -299,10 +299,10 @@ static int max31790_write_pwm(struct device *dev, u32 attr, int channel,
 			err = -EINVAL;
 			break;
 		}
-		data->pwm[channel] = val << 8;
+		data->valid = false;
 		err = i2c_smbus_write_word_swapped(client,
 						   MAX31790_REG_PWMOUT(channel),
-						   data->pwm[channel]);
+						   val << 8);
 		break;
 	case hwmon_pwm_enable:
 		fan_config = data->fan_config[channel];
-- 
2.30.2

[PATCH AUTOSEL 5.4 37/50] hwmon: (max31790) Fix pwmX_enable attributes

[Sasha Levin]

From: Guenter Roeck <linux@roeck-us.net>

[ Upstream commit 148c847c9e5a54b99850617bf9c143af9a344f92 ]

pwmX_enable supports three possible values:

0: Fan control disabled. Duty cycle is fixed to 0%
1: Fan control enabled, pwm mode. Duty cycle is determined by
   values written into Target Duty Cycle registers.
2: Fan control enabled, rpm mode
   Duty cycle is adjusted such that fan speed matches
   the values in Target Count registers

The current code does not do this; instead, it mixes pwm control
configuration with fan speed monitoring configuration. Worse, it
reports that pwm control would be disabled (pwmX_enable==0) when
it is in fact enabled in pwm mode. Part of the problem may be that
the chip sets the "TACH input enable" bit on its own whenever the
mode bit is set to RPM mode, but that doesn't mean that "TACH input
enable" accurately reflects the pwm mode.

Fix it up and only handle pwm control with the pwmX_enable attributes.
In the documentation, clarify that disabling pwm control (pwmX_enable=0)
sets the pwm duty cycle to 0%. In the code, explain why TACH_INPUT_EN
is set together with RPM_MODE.

While at it, only update the configuration register if the configuration
has changed, and only update the cached configuration if updating the
chip configuration was successful.

Cc: Jan Kundrát <jan.kundrat@cesnet.cz>
Cc: Václav Kubernát <kubernat@cesnet.cz>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Václav Kubernát <kubernat@cesnet.cz>
Reviewed-by: Jan Kundrát <jan.kundrat@cesnet.cz>
Link: https://lore.kernel.org/r/20210526154022.3223012-4-linux@roeck-us.net
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 Documentation/hwmon/max31790.rst |  2 +-
 drivers/hwmon/max31790.c         | 41 ++++++++++++++++++++------------
 2 files changed, 27 insertions(+), 16 deletions(-)

diff --git a/Documentation/hwmon/max31790.rst b/Documentation/hwmon/max31790.rst
index 9f12aac4fab5..f4749c44cfb8 100644
--- a/Documentation/hwmon/max31790.rst
+++ b/Documentation/hwmon/max31790.rst
@@ -38,7 +38,7 @@ Sysfs entries
 fan[1-12]_input    RO  fan tachometer speed in RPM
 fan[1-12]_fault    RO  fan experienced fault
 fan[1-6]_target    RW  desired fan speed in RPM
-pwm[1-6]_enable    RW  regulator mode, 0=disabled, 1=manual mode, 2=rpm mode
+pwm[1-6]_enable    RW  regulator mode, 0=disabled (duty cycle=0%), 1=manual mode, 2=rpm mode
 pwm[1-6]           RW  read: current pwm duty cycle,
                        write: target pwm duty cycle (0-255)
 ================== === =======================================================
diff --git a/drivers/hwmon/max31790.c b/drivers/hwmon/max31790.c
index 344be7829d58..21b6b63b1c07 100644
--- a/drivers/hwmon/max31790.c
+++ b/drivers/hwmon/max31790.c
@@ -27,6 +27,7 @@
 
 /* Fan Config register bits */
 #define MAX31790_FAN_CFG_RPM_MODE	0x80
+#define MAX31790_FAN_CFG_CTRL_MON	0x10
 #define MAX31790_FAN_CFG_TACH_INPUT_EN	0x08
 #define MAX31790_FAN_CFG_TACH_INPUT	0x01
 
@@ -271,12 +272,12 @@ static int max31790_read_pwm(struct device *dev, u32 attr, int channel,
 		*val = data->pwm[channel] >> 8;
 		return 0;
 	case hwmon_pwm_enable:
-		if (fan_config & MAX31790_FAN_CFG_RPM_MODE)
+		if (fan_config & MAX31790_FAN_CFG_CTRL_MON)
+			*val = 0;
+		else if (fan_config & MAX31790_FAN_CFG_RPM_MODE)
 			*val = 2;
-		else if (fan_config & MAX31790_FAN_CFG_TACH_INPUT_EN)
-			*val = 1;
 		else
-			*val = 0;
+			*val = 1;
 		return 0;
 	default:
 		return -EOPNOTSUPP;
@@ -307,23 +308,33 @@ static int max31790_write_pwm(struct device *dev, u32 attr, int channel,
 	case hwmon_pwm_enable:
 		fan_config = data->fan_config[channel];
 		if (val == 0) {
-			fan_config &= ~(MAX31790_FAN_CFG_TACH_INPUT_EN |
-					MAX31790_FAN_CFG_RPM_MODE);
+			fan_config |= MAX31790_FAN_CFG_CTRL_MON;
+			/*
+			 * Disable RPM mode; otherwise disabling fan speed
+			 * monitoring is not possible.
+			 */
+			fan_config &= ~MAX31790_FAN_CFG_RPM_MODE;
 		} else if (val == 1) {
-			fan_config = (fan_config |
-				      MAX31790_FAN_CFG_TACH_INPUT_EN) &
-				     ~MAX31790_FAN_CFG_RPM_MODE;
+			fan_config &= ~(MAX31790_FAN_CFG_CTRL_MON | MAX31790_FAN_CFG_RPM_MODE);
 		} else if (val == 2) {
-			fan_config |= MAX31790_FAN_CFG_TACH_INPUT_EN |
-				      MAX31790_FAN_CFG_RPM_MODE;
+			fan_config &= ~MAX31790_FAN_CFG_CTRL_MON;
+			/*
+			 * The chip sets MAX31790_FAN_CFG_TACH_INPUT_EN on its
+			 * own if MAX31790_FAN_CFG_RPM_MODE is set.
+			 * Do it here as well to reflect the actual register
+			 * value in the cache.
+			 */
+			fan_config |= (MAX31790_FAN_CFG_RPM_MODE | MAX31790_FAN_CFG_TACH_INPUT_EN);
 		} else {
 			err = -EINVAL;
 			break;
 		}
-		data->fan_config[channel] = fan_config;
-		err = i2c_smbus_write_byte_data(client,
-					MAX31790_REG_FAN_CONFIG(channel),
-					fan_config);
+		if (fan_config != data->fan_config[channel]) {
+			err = i2c_smbus_write_byte_data(client, MAX31790_REG_FAN_CONFIG(channel),
+							fan_config);
+			if (!err)
+				data->fan_config[channel] = fan_config;
+		}
 		break;
 	default:
 		err = -EOPNOTSUPP;
-- 
2.30.2