linux-kernel - [PATCH 5/5] hwmon: (adt7475) Add support for inverting pwm output

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Message-Id: <20200217234657.9413-6-chris.packham@alliedtelesis.co.nz>
Date:   Tue, 18 Feb 2020 12:46:57 +1300
From:   Chris Packham <chris.packham@...iedtelesis.co.nz>
To:     jdelvare@...e.com, linux@...ck-us.net, robh+dt@...nel.org,
        mark.rutland@....com
Cc:     logan.shaw@...iedtelesis.co.nz, linux-hwmon@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Chris Packham <chris.packham@...iedtelesis.co.nz>
Subject: [PATCH 5/5] hwmon: (adt7475) Add support for inverting pwm output

Add a "invert-pwm" device-tree property to allow hardware designs to use
inverted logic on the PWM output. Preserve the invert PWM output bit if
the property is not found to allow for bootloaders/bios which may have
configured this earlier.

Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
---
 drivers/hwmon/adt7475.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/drivers/hwmon/adt7475.c b/drivers/hwmon/adt7475.c
index 4a62d633a2f5..dccb1c78a57d 100644
--- a/drivers/hwmon/adt7475.c
+++ b/drivers/hwmon/adt7475.c
@@ -1509,6 +1509,41 @@ static int load_attenuators(const struct i2c_client *client, int chip,
 	return 0;
 }
 
+static int adt7475_set_pwm_polarity(struct i2c_client *client)
+{
+	char *prop;
+	int ret, i;
+	u8 val;
+
+	for (i = 0; i < ADT7475_PWM_COUNT; i++) {
+		ret = adt7475_read(PWM_CONFIG_REG(i));
+		if (ret < 0)
+			return ret;
+		val = ret;
+		switch (i) {
+		case 0:
+			prop = "invert-pwm1";
+			break;
+		case 1:
+			prop = "invert-pwm2";
+			break;
+		case 2:
+			prop = "invert-pwm3";
+			break;
+		}
+
+		ret = set_property_bit(client, prop, &val, 4);
+		if (ret)
+			continue;
+
+		ret = i2c_smbus_write_byte_data(client, PWM_CONFIG_REG(i), val);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
 static int adt7475_probe(struct i2c_client *client,
 			 const struct i2c_device_id *id)
 {
@@ -1617,6 +1652,10 @@ static int adt7475_probe(struct i2c_client *client,
 	for (i = 0; i < ADT7475_PWM_COUNT; i++)
 		adt7475_read_pwm(client, i);
 
+	ret = adt7475_set_pwm_polarity(client);
+	if (ret)
+		dev_err(&client->dev, "Error configuring pwm polarity");
+
 	/* Start monitoring */
 	switch (chip) {
 	case adt7475:
-- 
2.25.0