[PATCH v2 3/3] hwmon: max31785: Provide config of fault pin behavior

[Andrew Jeffery]

From: Christopher Bostic <cbostic at linux.vnet.ibm.com>

Provide interface to set behavior when FAULT pin is asserted.
When enabled force fan to 100% PWM duty cycle.

Signed-off-by: Christopher Bostic <cbostic at linux.vnet.ibm.com>
[Andrew Jeffery: Make it apply to reworked driver]
Signed-off-by: Andrew Jeffery <andrew at aj.id.au>
---
 drivers/hwmon/max31785.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)

diff --git a/drivers/hwmon/max31785.c b/drivers/hwmon/max31785.c
index ecece346be28..b4a350477ee5 100644
--- a/drivers/hwmon/max31785.c
+++ b/drivers/hwmon/max31785.c
@@ -38,6 +38,7 @@
 #define MAX31785_REG_MFR_ID			0x99
 #define MAX31785_REG_MFR_MODEL			0x9a
 #define MAX31785_REG_MFR_REVISION		0x9b
+#define MAX31785_REG_MFR_FAULT_RESP		0xd9
 #define MAX31785_REG_MFR_FAN_CONFIG		0xf1
 #define MAX31785_REG_READ_FAN_PWM		0xf3
 
@@ -51,6 +52,9 @@
 /* Fan Status register bits */
 #define MAX31785_FAN_STATUS_FAULT_MASK		0x80
 
+/* Fault response register bits */
+#define MAX31785_FAULT_RESP_PIN_MONITOR		0x01
+
 /* Fan Command constants */
 #define MAX31785_FAN_COMMAND_PWM_RATIO		40
 
@@ -755,6 +759,82 @@ static const struct hwmon_chip_info max31785_chip_info_0x3040 = {
 	.info = max31785_info_0x3040,
 };
 
+static ssize_t max31785_fault_resp_store(struct device *dev,
+				struct device_attribute *attr, const char *buf,
+				size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct max31785 *data = dev_get_drvdata(dev);
+	int rv;
+
+	mutex_lock(&data->lock);
+
+	rv = max31785_set_page(client, 0);
+	if (rv < 0)
+		goto done;
+
+	rv = i2c_smbus_read_byte_data(client, MAX31785_REG_MFR_FAULT_RESP);
+	if (rv < 0)
+		goto done;
+
+	if (!strncmp(buf, "on", strlen("on"))) {
+		if (!(rv & MAX31785_FAULT_RESP_PIN_MONITOR)) {
+			rv |= MAX31785_FAULT_RESP_PIN_MONITOR;
+			rv = i2c_smbus_write_byte_data(client,
+					MAX31785_REG_MFR_FAULT_RESP, rv);
+			if (rv < 0)
+				goto done;
+		}
+	} else if (!strncmp(buf, "off", strlen("off"))) {
+		if (rv & MAX31785_FAULT_RESP_PIN_MONITOR) {
+			rv &= ~MAX31785_FAULT_RESP_PIN_MONITOR;
+			rv = i2c_smbus_write_byte_data(client,
+					MAX31785_REG_MFR_FAULT_RESP, rv);
+			if (rv < 0)
+				goto done;
+		}
+	} else {
+		dev_warn(dev, "Unknown fault response type: [%s]\n", buf);
+		rv = -EINVAL;
+	}
+
+done:
+	mutex_unlock(&data->lock);
+
+	return rv;
+}
+
+static ssize_t max31785_fault_resp_show(struct device *dev,
+			       struct device_attribute *attr, char *buf)
+{
+	struct max31785 *data = max31785_update_device(dev);
+	struct i2c_client *client = to_i2c_client(dev);
+	int rv;
+
+	mutex_lock(&data->lock);
+
+	rv = max31785_set_page(client, 0);
+	if (rv < 0)
+		goto done;
+
+	rv = i2c_smbus_read_byte_data(client, MAX31785_REG_MFR_FAULT_RESP);
+	if (rv < 0)
+		goto done;
+
+	if (rv & MAX31785_FAULT_RESP_PIN_MONITOR)
+		rv = sprintf(buf, "on\n");
+	else
+		rv = sprintf(buf, "off\n");
+
+done:
+	mutex_unlock(&data->lock);
+
+	return rv;
+}
+
+static DEVICE_ATTR(fault_resp, 0644, max31785_fault_resp_show,
+		max31785_fault_resp_store);
+
 
 static int max31785_get_capabilities(struct max31785 *data)
 {
@@ -804,6 +884,10 @@ static int max31785_probe(struct i2c_client *client,
 	else
 		chip = &max31785_chip_info_0x3030;
 
+	rc = device_create_file(dev, &dev_attr_fault_resp);
+	if (rc)
+		return rc;
+
 	hwmon_dev = devm_hwmon_device_register_with_info(dev,
 			client->name, data, chip, NULL);
 
-- 
2.11.0