linux-kernel - [PATCH v2] hwmon: (max31790) add fanN

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Message-ID: <20220829195930.2521755-1-justinledford@google.com>
Date:   Mon, 29 Aug 2022 19:59:30 +0000
From:   Justin Ledford <justinledford@...gle.com>
To:     Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Jonathan Corbet <corbet@....net>
Cc:     linux-hwmon@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Justin Ledford <justinledford@...gle.com>
Subject: [PATCH v2] hwmon: (max31790) add fanN_enable

The MAX31790 has a tach input enable bit in each fan's configuration
register. This is only enabled by the driver if RPM mode is selected,
but the driver doesn't provide a way to independently enable tachometer
input regardless of the regulator mode.

By adding the fanN_enable sysfs files, we can decouple the tach input
from the regulator mode. Also update the documentation.

Signed-off-by: Justin Ledford <justinledford@...gle.com>
---
Changes in v2:
- Removed updating fan_config during max31790_update_device
---
 Documentation/hwmon/max31790.rst |  1 +
 drivers/hwmon/max31790.c         | 38 ++++++++++++++++++++++++++------
 2 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/Documentation/hwmon/max31790.rst b/Documentation/hwmon/max31790.rst
index 7b097c3b9b90..33c5c7330efc 100644
--- a/Documentation/hwmon/max31790.rst
+++ b/Documentation/hwmon/max31790.rst
@@ -38,6 +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
+fan[1-6]_enable    RW  enable or disable the tachometer input
 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 7e9362f6dc29..20bf5ffadefe 100644
--- a/drivers/hwmon/max31790.c
+++ b/drivers/hwmon/max31790.c
@@ -202,6 +202,9 @@ static int max31790_read_fan(struct device *dev, u32 attr, int channel,
 		}
 		mutex_unlock(&data->update_lock);
 		return 0;
+	case hwmon_fan_enable:
+		*val = !!(data->fan_config[channel] & MAX31790_FAN_CFG_TACH_INPUT_EN);
+		return 0;
 	default:
 		return -EOPNOTSUPP;
 	}
@@ -214,7 +217,7 @@ static int max31790_write_fan(struct device *dev, u32 attr, int channel,
 	struct i2c_client *client = data->client;
 	int target_count;
 	int err = 0;
-	u8 bits;
+	u8 bits, fan_config;
 	int sr;
 
 	mutex_lock(&data->update_lock);
@@ -243,6 +246,23 @@ 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_enable:
+		fan_config = data->fan_config[channel];
+		if (val == 0) {
+			fan_config &= ~MAX31790_FAN_CFG_TACH_INPUT_EN;
+		} else if (val == 1) {
+			fan_config |= MAX31790_FAN_CFG_TACH_INPUT_EN;
+		} else {
+			err = -EINVAL;
+			break;
+		}
+		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;
 		break;
@@ -270,6 +290,10 @@ static umode_t max31790_fan_is_visible(const void *_data, u32 attr, int channel)
 		    !(fan_config & MAX31790_FAN_CFG_TACH_INPUT))
 			return 0644;
 		return 0;
+	case hwmon_fan_enable:
+		if (channel < NR_CHANNEL)
+			return 0644;
+		return 0;
 	default:
 		return 0;
 	}
@@ -423,12 +447,12 @@ static umode_t max31790_is_visible(const void *data,
 
 static const struct hwmon_channel_info *max31790_info[] = {
 	HWMON_CHANNEL_INFO(fan,
-			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
-			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
-			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
-			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
-			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
-			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
+			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
+			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
+			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
+			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
+			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
+			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
 			   HWMON_F_INPUT | HWMON_F_FAULT,
 			   HWMON_F_INPUT | HWMON_F_FAULT,
 			   HWMON_F_INPUT | HWMON_F_FAULT,
-- 
2.37.2.672.g94769d06f0-goog