[PATCH] hwmon: (max31790) Add support for fanX_div

[Václav Kubernát]

Right now, the divisor (which determines the speed range) can be only
set by setting fanX_min or fanX_target. This is fine for RPM mode, but
in other cases, it might not be enough. This patch makes it possible to
set the divisor independently.

Signed-off-by: Václav Kubernát <kubernat@xxxxxxxxx>
---
 Documentation/hwmon/max31790.rst |  4 ++
 drivers/hwmon/max31790.c         | 68 ++++++++++++++++++++++++++------
 2 files changed, 60 insertions(+), 12 deletions(-)

diff --git a/Documentation/hwmon/max31790.rst b/Documentation/hwmon/max31790.rst
index 9225c2a78b68..818e4fe8c797 100644
--- a/Documentation/hwmon/max31790.rst
+++ b/Documentation/hwmon/max31790.rst
@@ -50,6 +50,10 @@ fan[1-12]_min      RW  minimum fan speed in RPM. Equivalent to target fan speed
                        and the chip will report a fault condition if the fan
                        speed is below the target fan speed.
 fan[1-6]_target    RW  desired fan speed in RPM
+fan[1-12]_div      RW  fan speed range
+		       The value is RO for companion channels (7-12). For those
+		       channels, the value matches the value of the primary channel.
+		       Setting fanX_target or fanX_min also sets this value.
 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 39a4ece4276a..f6c38094c19c 100644
--- a/drivers/hwmon/max31790.c
+++ b/drivers/hwmon/max31790.c
@@ -160,6 +160,26 @@ static u8 bits_for_tach_period(int rpm)
 	return bits;
 }
 
+static int bits_for_speed_range(long speed_range)
+{
+	switch (speed_range) {
+	case 1:
+		return 0x0;
+	case 2:
+		return 0x1;
+	case 4:
+		return 0x2;
+	case 8:
+		return 0x3;
+	case 16:
+		return 0x4;
+	case 32:
+		return 0x5;
+	default:
+		return -1;
+	}
+}
+
 static int max31790_read_fan(struct device *dev, u32 attr, int channel,
 			     long *val)
 {
@@ -173,6 +193,9 @@ static int max31790_read_fan(struct device *dev, u32 attr, int channel,
 	case hwmon_fan_enable:
 		*val = !!(data->fan_config[channel % NR_CHANNEL] & MAX31790_FAN_CFG_TACH_INPUT_EN);
 		return 0;
+	case hwmon_fan_div:
+		*val = get_tach_period(data->fan_dynamics[channel % NR_CHANNEL]);
+		return 0;
 	case hwmon_fan_input:
 		sr = get_tach_period(data->fan_dynamics[channel % NR_CHANNEL]);
 		if (data->tach[channel] == FAN_COUNT_REG_MAX)
@@ -293,6 +316,20 @@ static int max31790_write_fan(struct device *dev, u32 attr, int channel,
 					MAX31790_REG_TARGET_COUNT(channel),
 					data->target_count[channel]);
 		break;
+	case hwmon_fan_div:
+		sr = bits_for_speed_range(val);
+		if (sr < 0) {
+			err = -EINVAL;
+			break;
+		}
+
+		data->fan_dynamics[channel] = ((data->fan_dynamics[channel] &
+						~MAX31790_FAN_DYN_SR_MASK) |
+					       (sr << MAX31790_FAN_DYN_SR_SHIFT));
+		err = i2c_smbus_write_byte_data(client,
+						MAX31790_REG_FAN_DYNAMICS(channel),
+						data->fan_dynamics[channel]);
+		break;
 	default:
 		err = -EOPNOTSUPP;
 		break;
@@ -311,6 +348,7 @@ static umode_t max31790_fan_is_visible(const void *_data, u32 attr, int channel)
 	switch (attr) {
 	case hwmon_fan_min:
 	case hwmon_fan_enable:
+	case hwmon_fan_div:
 		if (channel < NR_CHANNEL)
 			return 0644;
 		if (fan_config & MAX31790_FAN_CFG_TACH_INPUT)
@@ -481,23 +519,29 @@ static umode_t max31790_is_visible(const void *data,
 static const struct hwmon_channel_info *max31790_info[] = {
 	HWMON_CHANNEL_INFO(fan,
 			   HWMON_F_ENABLE | HWMON_F_INPUT | HWMON_F_MIN | HWMON_F_TARGET |
-				HWMON_F_FAULT,
+				HWMON_F_FAULT | HWMON_F_DIV,
 			   HWMON_F_ENABLE | HWMON_F_INPUT | HWMON_F_MIN | HWMON_F_TARGET |
-				HWMON_F_FAULT,
+				HWMON_F_FAULT | HWMON_F_DIV,
 			   HWMON_F_ENABLE | HWMON_F_INPUT | HWMON_F_MIN | HWMON_F_TARGET |
-				HWMON_F_FAULT,
+				HWMON_F_FAULT | HWMON_F_DIV,
 			   HWMON_F_ENABLE | HWMON_F_INPUT | HWMON_F_MIN | HWMON_F_TARGET |
-				HWMON_F_FAULT,
+				HWMON_F_FAULT | HWMON_F_DIV,
 			   HWMON_F_ENABLE | HWMON_F_INPUT | HWMON_F_MIN | HWMON_F_TARGET |
-				HWMON_F_FAULT,
+				HWMON_F_FAULT | HWMON_F_DIV,
 			   HWMON_F_ENABLE | HWMON_F_INPUT | HWMON_F_MIN | HWMON_F_TARGET |
-				HWMON_F_FAULT,
-			   HWMON_F_ENABLE | HWMON_F_INPUT | HWMON_F_MIN | HWMON_F_FAULT,
-			   HWMON_F_ENABLE | HWMON_F_INPUT | HWMON_F_MIN | HWMON_F_FAULT,
-			   HWMON_F_ENABLE | HWMON_F_INPUT | HWMON_F_MIN | HWMON_F_FAULT,
-			   HWMON_F_ENABLE | HWMON_F_INPUT | HWMON_F_MIN | HWMON_F_FAULT,
-			   HWMON_F_ENABLE | HWMON_F_INPUT | HWMON_F_MIN | HWMON_F_FAULT,
-			   HWMON_F_ENABLE | HWMON_F_INPUT | HWMON_F_MIN | HWMON_F_FAULT),
+				HWMON_F_FAULT | HWMON_F_DIV,
+			   HWMON_F_ENABLE | HWMON_F_INPUT | HWMON_F_MIN | HWMON_F_FAULT |
+				HWMON_F_DIV,
+			   HWMON_F_ENABLE | HWMON_F_INPUT | HWMON_F_MIN | HWMON_F_FAULT |
+				HWMON_F_DIV,
+			   HWMON_F_ENABLE | HWMON_F_INPUT | HWMON_F_MIN | HWMON_F_FAULT |
+				 HWMON_F_DIV,
+			   HWMON_F_ENABLE | HWMON_F_INPUT | HWMON_F_MIN | HWMON_F_FAULT |
+				 HWMON_F_DIV,
+			   HWMON_F_ENABLE | HWMON_F_INPUT | HWMON_F_MIN | HWMON_F_FAULT |
+				   HWMON_F_DIV,
+			   HWMON_F_ENABLE | HWMON_F_INPUT | HWMON_F_MIN | HWMON_F_FAULT |
+				   HWMON_F_DIV),
 	HWMON_CHANNEL_INFO(pwm,
 			   HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
 			   HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
-- 
2.31.1