linux-kernel - [PATCH v5 5/5] hwmon: (adt7475) Add support for inverting pwm output

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Date:   Thu, 27 Feb 2020 21:46:42 +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 v5 5/5] hwmon: (adt7475) Add support for inverting pwm output

Add a "adi,pwm-active-state" device-tree property to allow hardware
designs to use inverted logic on the PWM output.

Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
---

Notes:
    Changes in v5:
    - change to adi,pwm-active-state
    - uint32 array
    
    Changes in v4:
    - use vendor prefix for new property
    
    Changes in v3:
    - New

 drivers/hwmon/adt7475.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/drivers/hwmon/adt7475.c b/drivers/hwmon/adt7475.c
index 3649b18359dc..142a4fec688b 100644
--- a/drivers/hwmon/adt7475.c
+++ b/drivers/hwmon/adt7475.c
@@ -1509,6 +1509,36 @@ static int load_attenuators(const struct i2c_client *client, int chip,
 	return 0;
 }
 
+static int adt7475_set_pwm_polarity(struct i2c_client *client)
+{
+	u32 states[ADT7475_PWM_COUNT];
+	int ret, i;
+	u8 val;
+
+	ret = of_property_read_u32_array(client->dev.of_node,
+					 "adi,pwm-active-state", states,
+					 ARRAY_SIZE(states));
+	if (ret)
+		return ret;
+
+	for (i = 0; i < ADT7475_PWM_COUNT; i++) {
+		ret = adt7475_read(PWM_CONFIG_REG(i));
+		if (ret < 0)
+			return ret;
+		val = ret;
+		if (states[i])
+			val &= ~BIT(4);
+		else
+			val |= BIT(4);
+
+		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 +1647,10 @@ 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 && ret != -EINVAL)
+		dev_err(&client->dev, "Error configuring pwm polarity\n");
+
 	/* Start monitoring */
 	switch (chip) {
 	case adt7475:
-- 
2.25.1