[PATCH v8 4/4] hwmon: (max6639) Add pwm support

[Naresh Solanki]

Add pwm support for max6639. Also configure pwm fan speed based on pwm
provided in DT.

Signed-off-by: Naresh Solanki <Naresh.Solanki@xxxxxxxxxxxxx>
---
 drivers/hwmon/Kconfig   |   1 +
 drivers/hwmon/max6639.c | 243 +++++++++++++++++++++++++++++++++++++---
 2 files changed, 230 insertions(+), 14 deletions(-)

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 3176c33af6c6..56d9004b7a38 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1115,6 +1115,7 @@ config SENSORS_MAX6621
 config SENSORS_MAX6639
 	tristate "Maxim MAX6639 sensor chip"
 	depends on I2C
+	depends on PWM
 	help
 	  If you say yes here you get support for the MAX6639
 	  sensor chips.
diff --git a/drivers/hwmon/max6639.c b/drivers/hwmon/max6639.c
index e09358713bef..302186532e0f 100644
--- a/drivers/hwmon/max6639.c
+++ b/drivers/hwmon/max6639.c
@@ -19,6 +19,7 @@
 #include <linux/hwmon-sysfs.h>
 #include <linux/err.h>
 #include <linux/mutex.h>
+#include <linux/pwm.h>
 
 /* Addresses to scan */
 static const unsigned short normal_i2c[] = { 0x2c, 0x2e, 0x2f, I2C_CLIENT_END };
@@ -53,11 +54,17 @@ static const unsigned short normal_i2c[] = { 0x2c, 0x2e, 0x2f, I2C_CLIENT_END };
 #define MAX6639_GCONFIG_PWM_FREQ_HI		0x08
 
 #define MAX6639_FAN_CONFIG1_PWM			0x80
-
+#define MAX6639_REG_FAN_CONFIG2a_PWM_POL	0x02
 #define MAX6639_FAN_CONFIG3_THERM_FULL_SPEED	0x40
+#define MAX6639_FAN_CONFIG3_FREQ_MASK		0x03
+#define MAX6639_REG_TARGTDUTY_SLOT		120
 
 static const int rpm_ranges[] = { 2000, 4000, 8000, 16000 };
 
+/* Supported PWM frequency */
+static const unsigned int freq_table[] = { 20, 33, 50, 100, 5000, 8333, 12500,
+					   25000 };
+
 #define FAN_FROM_REG(val, rpm_range)	((val) == 0 || (val) == 255 ? \
 				0 : (rpm_ranges[rpm_range] * 30) / (val))
 #define TEMP_LIMIT_TO_REG(val)	clamp_val((val) / 1000, 0, 255)
@@ -75,6 +82,9 @@ struct max6639_data {
 	u16 temp[2];		/* Temperature, in 1/8 C, 0..255 C */
 	bool temp_fault[2];	/* Detected temperature diode failure */
 	u8 fan[2];		/* Register value: TACH count for fans >=30 */
+	struct pwm_device *pwmd[2]; /* max6639 has two pwm device */
+	u32 target_rpm[2];
+	u32 max_rpm[2];
 	u8 status;		/* Detected channel alarms and fan failures */
 
 	/* Register values only written to */
@@ -89,6 +99,8 @@ struct max6639_data {
 
 	/* Optional regulator for FAN supply */
 	struct regulator *reg;
+	/* max6639 pwm chip */
+	struct pwm_chip chip;
 };
 
 static struct max6639_data *max6639_update_device(struct device *dev)
@@ -279,8 +291,11 @@ static ssize_t pwm_show(struct device *dev, struct device_attribute *dev_attr,
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
 	struct max6639_data *data = dev_get_drvdata(dev);
+	struct pwm_state state;
+
+	pwm_get_state(data->pwmd[attr->index], &state);
 
-	return sprintf(buf, "%d\n", data->pwm[attr->index] * 255 / 120);
+	return sprintf(buf, "%d\n", pwm_get_relative_duty_cycle(&state, 255));
 }
 
 static ssize_t pwm_store(struct device *dev,
@@ -289,9 +304,9 @@ static ssize_t pwm_store(struct device *dev,
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
 	struct max6639_data *data = dev_get_drvdata(dev);
-	struct i2c_client *client = data->client;
 	unsigned long val;
 	int res;
+	struct pwm_state state;
 
 	res = kstrtoul(buf, 10, &val);
 	if (res)
@@ -299,12 +314,12 @@ static ssize_t pwm_store(struct device *dev,
 
 	val = clamp_val(val, 0, 255);
 
-	mutex_lock(&data->update_lock);
-	data->pwm[attr->index] = (u8)(val * 120 / 255);
-	i2c_smbus_write_byte_data(client,
-				  MAX6639_REG_TARGTDUTY(attr->index),
-				  data->pwm[attr->index]);
-	mutex_unlock(&data->update_lock);
+	pwm_get_state(data->pwmd[attr->index], &state);
+	pwm_set_relative_duty_cycle(&state, val, 255);
+	res = pwm_apply_state(data->pwmd[attr->index], &state);
+	if (res)
+		return res;
+
 	return count;
 }
 
@@ -404,6 +419,7 @@ static int max6639_init_client(struct i2c_client *client,
 			       struct max6639_data *data)
 {
 	int i, err;
+	struct pwm_state state;
 
 	/* Reset chip to default values, see below for GCONFIG setup */
 	err = i2c_smbus_write_byte_data(client, MAX6639_REG_GCONFIG,
@@ -457,10 +473,11 @@ static int max6639_init_client(struct i2c_client *client,
 		if (err)
 			goto exit;
 
-		/* PWM 120/120 (i.e. 100%) */
-		data->pwm[i] = 120;
-		err = i2c_smbus_write_byte_data(client,
-				MAX6639_REG_TARGTDUTY(i), data->pwm[i]);
+		/* Configure PWM controller */
+		pwm_get_state(data->pwmd[i], &state);
+		pwm_set_relative_duty_cycle(&state, data->target_rpm[i],
+					   data->max_rpm[i]);
+		err = pwm_apply_state(data->pwmd[i], &state);
 		if (err)
 			goto exit;
 	}
@@ -539,8 +556,31 @@ static int max6639_probe_child_from_dt(struct i2c_client *client,
 	}
 
 	data->rpm_range[i] = rpm_range_to_reg(maxrpm);
+	data->max_rpm[i] = maxrpm;
 
-	return 0;
+	err = of_property_read_u32(child, "target-rpm", &val);
+	/* Use provided target RPM else default to maxrpm */
+	if (!err)
+		data->target_rpm[i] = val;
+	else
+		data->target_rpm[i] = maxrpm;
+
+	/* Get pwms property for PWM control */
+	data->pwmd[i] = devm_fwnode_pwm_get(dev, &child->fwnode, NULL);
+
+	if (!IS_ERR(data->pwmd[i]))
+		return 0;
+
+	if (PTR_ERR(data->pwmd[i]) == -EPROBE_DEFER)
+		return PTR_ERR(data->pwmd[i]);
+
+	dev_dbg(dev, "Using chip default PWM");
+	data->pwmd[i] = pwm_request_from_chip(&data->chip, i, NULL);
+	if (!IS_ERR(data->pwmd[i]))
+		return 0;
+
+	dev_dbg(dev, "Failed to configure pwm for fan %d", i);
+	return PTR_ERR_OR_ZERO(data->pwmd[i]);
 }
 static int max6639_probe_from_dt(struct i2c_client *client,
 				struct max6639_data *data)
@@ -568,6 +608,172 @@ static int max6639_probe_from_dt(struct i2c_client *client,
 	return 0;
 }
 
+static struct max6639_data *to_max6639_pwm(struct pwm_chip *chip)
+{
+	return container_of(chip, struct max6639_data, chip);
+}
+
+static void max6639_pwm_get_state(struct pwm_chip *chip,
+				  struct pwm_device *pwm,
+				  struct pwm_state *state)
+{
+
+	struct max6639_data *data = to_max6639_pwm(chip);
+	struct i2c_client *client = data->client;
+	int value, i = pwm->hwpwm, x;
+	unsigned int freq;
+
+	mutex_lock(&data->update_lock);
+
+	value = i2c_smbus_read_byte_data(client, MAX6639_REG_FAN_CONFIG1(i));
+	if (value < 0)
+		goto abort;
+
+	if (value & MAX6639_FAN_CONFIG1_PWM) {
+		state->enabled = true;
+
+		/* Determine frequency from respective registers */
+		value = i2c_smbus_read_byte_data(client,
+						 MAX6639_REG_FAN_CONFIG3(i));
+		if (value < 0)
+			goto abort;
+		x = value & MAX6639_FAN_CONFIG3_FREQ_MASK;
+
+		value = i2c_smbus_read_byte_data(client, MAX6639_REG_GCONFIG);
+		if (value < 0)
+			goto abort;
+		if (value & MAX6639_GCONFIG_PWM_FREQ_HI)
+			x |= 0x4;
+		x &= 0x7;
+		freq = freq_table[x];
+
+		state->period = DIV_ROUND_UP(NSEC_PER_SEC, freq);
+
+		value = i2c_smbus_read_byte_data(client,
+						 MAX6639_REG_TARGTDUTY(i));
+		if (value < 0)
+			goto abort;
+		/* max6639 supports 120 slots only */
+		state->duty_cycle = mul_u64_u32_div(state->period, value, 120);
+
+		value = i2c_smbus_read_byte_data(client,
+						 MAX6639_REG_FAN_CONFIG2a(i));
+		if (value < 0)
+			goto abort;
+		value &= MAX6639_REG_FAN_CONFIG2a_PWM_POL;
+		state->polarity = (value != 0);
+	} else
+		state->enabled = false;
+
+abort:
+	mutex_unlock(&data->update_lock);
+
+}
+
+static int max6639_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			     const struct pwm_state *state)
+{
+	struct max6639_data *data = to_max6639_pwm(chip);
+	struct i2c_client *client = data->client;
+	int value = 0, i = pwm->hwpwm, x;
+	unsigned int freq;
+	struct pwm_state cstate;
+
+	cstate = pwm->state;
+
+	mutex_lock(&data->update_lock);
+
+	if (state->period != cstate.period) {
+		/* Configure frequency */
+		freq = DIV_ROUND_UP_ULL(NSEC_PER_SEC, state->period);
+		/* Chip supports limited number of frequency */
+		for (x = 0; x < sizeof(freq_table); x++)
+			if (freq <= freq_table[x])
+				break;
+
+		value = i2c_smbus_read_byte_data(client,
+						 MAX6639_REG_FAN_CONFIG3(i));
+		if (value < 0)
+			goto abort;
+		value &= ~MAX6639_FAN_CONFIG3_FREQ_MASK;
+		value |= (x & MAX6639_FAN_CONFIG3_FREQ_MASK);
+		value = i2c_smbus_write_byte_data(client,
+						  MAX6639_REG_FAN_CONFIG3(i),
+						  value);
+
+		value = i2c_smbus_read_byte_data(client, MAX6639_REG_GCONFIG);
+		if (value < 0)
+			goto abort;
+
+		if (x >> 2)
+			value &= ~MAX6639_GCONFIG_PWM_FREQ_HI;
+		else
+			value |= MAX6639_GCONFIG_PWM_FREQ_HI;
+		value = i2c_smbus_write_byte_data(client, MAX6639_REG_GCONFIG,
+						  value);
+		if (value < 0)
+			goto abort;
+	}
+
+	/* Configure dutycycle */
+	if (state->duty_cycle != cstate.duty_cycle ||
+	    state->period != cstate.period) {
+		value = DIV_ROUND_DOWN_ULL(
+				state->duty_cycle * MAX6639_REG_TARGTDUTY_SLOT,
+				state->period);
+		value = i2c_smbus_write_byte_data(client,
+						  MAX6639_REG_TARGTDUTY(i),
+						  value);
+		if (value < 0)
+			goto abort;
+	}
+
+	/* Configure polarity */
+	if (state->polarity != cstate.polarity) {
+		value = i2c_smbus_read_byte_data(client,
+						 MAX6639_REG_FAN_CONFIG2a(i));
+		if (value < 0)
+			goto abort;
+		if (state->polarity == PWM_POLARITY_NORMAL)
+			value |= MAX6639_REG_FAN_CONFIG2a_PWM_POL;
+		else
+			value &= ~MAX6639_REG_FAN_CONFIG2a_PWM_POL;
+		value = i2c_smbus_write_byte_data(client,
+						  MAX6639_REG_FAN_CONFIG2a(i),
+						  value);
+		if (value < 0)
+			goto abort;
+	}
+
+	if (state->enabled == cstate.enabled)
+		goto abort;
+
+	value = i2c_smbus_read_byte_data(client, MAX6639_REG_FAN_CONFIG1(i));
+	if (value < 0)
+		goto abort;
+	if (state->enabled)
+		value |= MAX6639_FAN_CONFIG1_PWM;
+	else
+		value &= ~MAX6639_FAN_CONFIG1_PWM;
+
+	value = i2c_smbus_write_byte_data(client, MAX6639_REG_FAN_CONFIG1(i),
+					  value);
+	if (value < 0)
+		goto abort;
+	value = 0;
+
+abort:
+	mutex_unlock(&data->update_lock);
+
+	return value;
+}
+
+static const struct pwm_ops max6639_pwm_ops = {
+	.apply = max6639_pwm_apply,
+	.get_state = max6639_pwm_get_state,
+	.owner = THIS_MODULE,
+};
+
 static int max6639_probe(struct i2c_client *client)
 {
 	struct device *dev = &client->dev;
@@ -581,6 +787,15 @@ static int max6639_probe(struct i2c_client *client)
 
 	data->client = client;
 
+	/* Add PWM controller of max6639 */
+	data->chip.dev = dev;
+	data->chip.ops = &max6639_pwm_ops;
+	data->chip.npwm = 2;
+
+	err = devm_pwmchip_add(dev, &data->chip);
+	if (err < 0)
+		return dev_err_probe(dev, err, "failed to add PWM chip\n");
+
 	data->reg = devm_regulator_get_optional(dev, "fan");
 	if (IS_ERR(data->reg)) {
 		if (PTR_ERR(data->reg) != -ENODEV)
-- 
2.37.3