Message-Id: <20170908043919.6924-3-andrew@aj.id.au>
Date:   Fri,  8 Sep 2017 14:39:18 +1000
From:   Andrew Jeffery <andrew@...id.au>
To:     linux@...ck-us.net, linux-hwmon@...r.kernel.org
Cc:     Andrew Jeffery <andrew@...id.au>, robh+dt@...nel.org,
        mark.rutland@....com, jdelvare@...e.com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        joel@....id.au, mspinler@...ux.vnet.ibm.com,
        msbarth@...ux.vnet.ibm.com, openbmc@...ts.ozlabs.org
Subject: [PATCH v3 2/3] hwmon: pmbus: Add fan control support

Expose fanX_target, pwmX and pwmX_enable hwmon sysfs attributes.

Fans in a PMBus device are driven by the configuration of two registers:
FAN_CONFIG_x_y and FAN_COMMAND_x: FAN_CONFIG_x_y dictates how the fan
and the tacho operate (if installed), while FAN_COMMAND_x sets the
desired fan rate. The unit of FAN_COMMAND_x is dependent on the
operational fan mode, RPM or PWM percent duty, as determined by the
corresponding FAN_CONFIG_x_y.

The mapping of fanX_target, pwmX and pwmX_enable onto FAN_CONFIG_x_y and
FAN_COMMAND_x is implemented with the addition of virtual registers and
generic implementations in the core:

1. PMBUS_VIRT_FAN_TARGET_x
2. PMBUS_VIRT_PWM_x
3. PMBUS_VIRT_PWM_ENABLE_x

The virtual registers facilitate the necessary side-effects of each
access. Examples of the read case, assuming m = 1, b = 0, R = 0:

             Read     |              With              || Gives
         -------------------------------------------------------
           Attribute  | FAN_CONFIG_x_y | FAN_COMMAND_y || Value
         ----------------------------------------------++-------
          fanX_target | ~PB_FAN_z_RPM  | 0x0001        || 1
          pwm1        | ~PB_FAN_z_RPM  | 0x0064        || 255
          pwmX_enable | ~PB_FAN_z_RPM  | 0x0001        || 1
          fanX_target |  PB_FAN_z_RPM  | 0x0001        || 1
          pwm1        |  PB_FAN_z_RPM  | 0x0064        || 0
          pwmX_enable |  PB_FAN_z_RPM  | 0x0001        || 1

And the write case:

             Write    | With  ||               Sets
         -------------+-------++----------------+---------------
           Attribute  | Value || FAN_CONFIG_x_y | FAN_COMMAND_x
         -------------+-------++----------------+---------------
          fanX_target | 1     ||  PB_FAN_z_RPM  | 0x0001
          pwmX        | 255   || ~PB_FAN_z_RPM  | 0x0064
          pwmX_enable | 1     || ~PB_FAN_z_RPM  | 0x0064

Also, the DIRECT mode scaling of some controllers is different between
RPM and PWM percent duty control modes, so PSC_PWM is introduced to
capture the necessary coefficients.

Signed-off-by: Andrew Jeffery <andrew@...id.au>
---
 drivers/hwmon/pmbus/pmbus.h      |  29 +++++
 drivers/hwmon/pmbus/pmbus_core.c | 224 ++++++++++++++++++++++++++++++++++++---
 2 files changed, 238 insertions(+), 15 deletions(-)

diff --git a/drivers/hwmon/pmbus/pmbus.h b/drivers/hwmon/pmbus/pmbus.h
index bfcb13bae34b..a863b8fed16f 100644
--- a/drivers/hwmon/pmbus/pmbus.h
+++ b/drivers/hwmon/pmbus/pmbus.h
@@ -190,6 +190,28 @@ enum pmbus_regs {
 	PMBUS_VIRT_VMON_UV_FAULT_LIMIT,
 	PMBUS_VIRT_VMON_OV_FAULT_LIMIT,
 	PMBUS_VIRT_STATUS_VMON,
+
+	/*
+	 * RPM and PWM Fan control
+	 *
+	 * Drivers wanting to expose PWM control must define the behaviour of
+	 * PMBUS_VIRT_PWM_ENABLE_[1-4] in the {read,write}_word_data callback.
+	 *
+	 * pmbus core provides default implementations for
+	 * PMBUS_VIRT_FAN_TARGET_[1-4] and PMBUS_VIRT_PWM_[1-4].
+	 */
+	PMBUS_VIRT_FAN_TARGET_1,
+	PMBUS_VIRT_FAN_TARGET_2,
+	PMBUS_VIRT_FAN_TARGET_3,
+	PMBUS_VIRT_FAN_TARGET_4,
+	PMBUS_VIRT_PWM_1,
+	PMBUS_VIRT_PWM_2,
+	PMBUS_VIRT_PWM_3,
+	PMBUS_VIRT_PWM_4,
+	PMBUS_VIRT_PWM_ENABLE_1,
+	PMBUS_VIRT_PWM_ENABLE_2,
+	PMBUS_VIRT_PWM_ENABLE_3,
+	PMBUS_VIRT_PWM_ENABLE_4,
 };
 
 /*
@@ -223,6 +245,8 @@ enum pmbus_regs {
 #define PB_FAN_1_RPM			BIT(6)
 #define PB_FAN_1_INSTALLED		BIT(7)
 
+enum pmbus_fan_mode { percent = 0, rpm };
+
 /*
  * STATUS_BYTE, STATUS_WORD (lower)
  */
@@ -313,6 +337,7 @@ enum pmbus_sensor_classes {
 	PSC_POWER,
 	PSC_TEMPERATURE,
 	PSC_FAN,
+	PSC_PWM,
 	PSC_NUM_CLASSES		/* Number of power sensor classes */
 };
 
@@ -339,6 +364,8 @@ enum pmbus_sensor_classes {
 #define PMBUS_HAVE_STATUS_FAN34	BIT(17)
 #define PMBUS_HAVE_VMON		BIT(18)
 #define PMBUS_HAVE_STATUS_VMON	BIT(19)
+#define PMBUS_HAVE_PWM12	BIT(20)
+#define PMBUS_HAVE_PWM34	BIT(21)
 
 enum pmbus_data_format { linear = 0, direct, vid };
 enum vrm_version { vr11 = 0, vr12 };
@@ -413,6 +440,8 @@ int pmbus_write_byte_data(struct i2c_client *client, int page, u8 reg,
 			  u8 value);
 int pmbus_update_byte_data(struct i2c_client *client, int page, u8 reg,
 			   u8 mask, u8 value);
+int pmbus_update_fan(struct i2c_client *client, int page, int id,
+		     u8 config, u8 mask, u16 command);
 void pmbus_clear_faults(struct i2c_client *client);
 bool pmbus_check_byte_register(struct i2c_client *client, int page, int reg);
 bool pmbus_check_word_register(struct i2c_client *client, int page, int reg);
diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index f1eff6b6c798..5ed9cbf1daf9 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -63,6 +63,7 @@ struct pmbus_sensor {
 	u16 reg;		/* register */
 	enum pmbus_sensor_classes class;	/* sensor class */
 	bool update;		/* runtime sensor update needed */
+	bool convert;		/* Whether or not to apply linear/vid/direct */
 	int data;		/* Sensor data.
 				   Negative if there was a read error */
 };
@@ -118,6 +119,27 @@ struct pmbus_data {
 	u8 currpage;
 };
 
+static const int pmbus_fan_rpm_mask[] = {
+	PB_FAN_1_RPM,
+	PB_FAN_2_RPM,
+	PB_FAN_1_RPM,
+	PB_FAN_2_RPM,
+};
+
+static const int pmbus_fan_config_registers[] = {
+	PMBUS_FAN_CONFIG_12,
+	PMBUS_FAN_CONFIG_12,
+	PMBUS_FAN_CONFIG_34,
+	PMBUS_FAN_CONFIG_34
+};
+
+static const int pmbus_fan_command_registers[] = {
+	PMBUS_FAN_COMMAND_1,
+	PMBUS_FAN_COMMAND_2,
+	PMBUS_FAN_COMMAND_3,
+	PMBUS_FAN_COMMAND_4,
+};
+
 void pmbus_clear_cache(struct i2c_client *client)
 {
 	struct pmbus_data *data = i2c_get_clientdata(client);
@@ -188,6 +210,31 @@ int pmbus_write_word_data(struct i2c_client *client, u8 page, u8 reg, u16 word)
 }
 EXPORT_SYMBOL_GPL(pmbus_write_word_data);
 
+int pmbus_update_fan(struct i2c_client *client, int page, int id,
+			       u8 config, u8 mask, u16 command)
+{
+	int from, rv;
+	u8 to;
+
+	from = pmbus_read_byte_data(client, page,
+				    pmbus_fan_config_registers[id]);
+	if (from < 0)
+		return from;
+
+	to = (from & ~mask) | (config & mask);
+
+	if (to != from) {
+		rv = pmbus_write_byte_data(client, page,
+					   pmbus_fan_config_registers[id], to);
+		if (rv < 0)
+			return rv;
+	}
+
+	return pmbus_write_word_data(client, page,
+				     pmbus_fan_command_registers[id], command);
+}
+EXPORT_SYMBOL_GPL(pmbus_update_fan);
+
 /*
  * _pmbus_write_word_data() is similar to pmbus_write_word_data(), but checks if
  * a device specific mapping function exists and calls it if necessary.
@@ -204,8 +251,40 @@ static int _pmbus_write_word_data(struct i2c_client *client, int page, int reg,
 		if (status != -ENODATA)
 			return status;
 	}
-	if (reg >= PMBUS_VIRT_BASE)
-		return -ENXIO;
+	if (reg >= PMBUS_VIRT_BASE) {
+		int id, bit;
+
+		switch (reg) {
+		case PMBUS_VIRT_FAN_TARGET_1:
+		case PMBUS_VIRT_FAN_TARGET_2:
+		case PMBUS_VIRT_FAN_TARGET_3:
+		case PMBUS_VIRT_FAN_TARGET_4:
+			id = reg - PMBUS_VIRT_FAN_TARGET_1;
+			bit = pmbus_fan_rpm_mask[id];
+			status = pmbus_update_fan(client, page, id, bit, bit,
+						  word);
+			break;
+		case PMBUS_VIRT_PWM_1:
+		case PMBUS_VIRT_PWM_2:
+		case PMBUS_VIRT_PWM_3:
+		case PMBUS_VIRT_PWM_4:
+		{
+			u32 command = word;
+
+			id = reg - PMBUS_VIRT_PWM_1;
+			bit = pmbus_fan_rpm_mask[id];
+			command *= 100;
+			command /= 255;
+			status = pmbus_update_fan(client, page, id, 0, bit,
+						  command);
+			break;
+		}
+		default:
+			status = -ENXIO;
+			break;
+		}
+		return status;
+	}
 	return pmbus_write_word_data(client, page, reg, word);
 }
 
@@ -221,6 +300,9 @@ int pmbus_read_word_data(struct i2c_client *client, u8 page, u8 reg)
 }
 EXPORT_SYMBOL_GPL(pmbus_read_word_data);
 
+static int pmbus_get_fan_command(struct i2c_client *client, int page, int id,
+				 enum pmbus_fan_mode mode);
+
 /*
  * _pmbus_read_word_data() is similar to pmbus_read_word_data(), but checks if
  * a device specific mapping function exists and calls it if necessary.
@@ -236,8 +318,42 @@ static int _pmbus_read_word_data(struct i2c_client *client, int page, int reg)
 		if (status != -ENODATA)
 			return status;
 	}
-	if (reg >= PMBUS_VIRT_BASE)
-		return -ENXIO;
+	if (reg >= PMBUS_VIRT_BASE) {
+		int id;
+
+		switch (reg) {
+		case PMBUS_VIRT_FAN_TARGET_1:
+		case PMBUS_VIRT_FAN_TARGET_2:
+		case PMBUS_VIRT_FAN_TARGET_3:
+		case PMBUS_VIRT_FAN_TARGET_4:
+			id = reg - PMBUS_VIRT_FAN_TARGET_1;
+			status = pmbus_get_fan_command(client, page, id, rpm);
+			break;
+		case PMBUS_VIRT_PWM_1:
+		case PMBUS_VIRT_PWM_2:
+		case PMBUS_VIRT_PWM_3:
+		case PMBUS_VIRT_PWM_4:
+		{
+			int rv;
+
+			id = reg - PMBUS_VIRT_PWM_1;
+			rv = pmbus_get_fan_command(client, page, id, percent);
+			if (rv < 0)
+				return rv;
+
+			rv *= 255;
+			rv /= 100;
+
+			status = rv;
+			break;
+		}
+		default:
+			status = -ENXIO;
+			break;
+		}
+
+		return status;
+	}
 	return pmbus_read_word_data(client, page, reg);
 }
 
@@ -304,6 +420,28 @@ static int _pmbus_read_byte_data(struct i2c_client *client, int page, int reg)
 	return pmbus_read_byte_data(client, page, reg);
 }
 
+static int pmbus_get_fan_command(struct i2c_client *client, int page, int id,
+				 enum pmbus_fan_mode mode)
+{
+	int config;
+
+	config = _pmbus_read_byte_data(client, page,
+				       pmbus_fan_config_registers[id]);
+	if (config < 0)
+		return config;
+
+	/*
+	 * We can't meaningfully translate between PWM and RPM, so if the
+	 * attribute mode (fan[1-*]_target is RPM, pwm[1-*] and pwm[1-*]_enable
+	 * are PWM) doesn't match the hardware mode, then report 0 instead.
+	 */
+	if ((mode == rpm) != (!!(config & pmbus_fan_rpm_mask[id])))
+		return 0;
+
+	return _pmbus_read_word_data(client, page,
+				     pmbus_fan_command_registers[id]);
+}
+
 static void pmbus_clear_fault_page(struct i2c_client *client, int page)
 {
 	_pmbus_write_byte(client, page, PMBUS_CLEAR_FAULTS);
@@ -489,7 +627,7 @@ static long pmbus_reg2data_direct(struct pmbus_data *data,
 	/* X = 1/m * (Y * 10^-R - b) */
 	R = -R;
 	/* scale result to milli-units for everything but fans */
-	if (sensor->class != PSC_FAN) {
+	if (!(sensor->class == PSC_FAN || sensor->class == PSC_PWM)) {
 		R += 3;
 		b *= 1000;
 	}
@@ -539,6 +677,9 @@ static long pmbus_reg2data(struct pmbus_data *data, struct pmbus_sensor *sensor)
 {
 	long val;
 
+	if (!sensor->convert)
+		return sensor->data;
+
 	switch (data->info->format[sensor->class]) {
 	case direct:
 		val = pmbus_reg2data_direct(data, sensor);
@@ -642,7 +783,7 @@ static u16 pmbus_data2reg_direct(struct pmbus_data *data,
 	}
 
 	/* Calculate Y = (m * X + b) * 10^R */
-	if (sensor->class != PSC_FAN) {
+	if (!(sensor->class == PSC_FAN || sensor->class == PSC_PWM)) {
 		R -= 3;		/* Adjust R and b for data in milli-units */
 		b *= 1000;
 	}
@@ -673,6 +814,9 @@ static u16 pmbus_data2reg(struct pmbus_data *data,
 {
 	u16 regval;
 
+	if (!sensor->convert)
+		return val;
+
 	switch (data->info->format[sensor->class]) {
 	case direct:
 		regval = pmbus_data2reg_direct(data, sensor, val);
@@ -895,12 +1039,18 @@ static struct pmbus_sensor *pmbus_add_sensor(struct pmbus_data *data,
 		return NULL;
 	a = &sensor->attribute;
 
-	snprintf(sensor->name, sizeof(sensor->name), "%s%d_%s",
-		 name, seq, type);
+	if (type)
+		snprintf(sensor->name, sizeof(sensor->name), "%s%d_%s",
+			 name, seq, type);
+	else
+		snprintf(sensor->name, sizeof(sensor->name), "%s%d",
+			 name, seq);
+
 	sensor->page = page;
 	sensor->reg = reg;
 	sensor->class = class;
 	sensor->update = update;
+	sensor->convert = true;
 	pmbus_dev_attr_init(a, sensor->name,
 			    readonly ? S_IRUGO : S_IRUGO | S_IWUSR,
 			    pmbus_show_sensor, pmbus_set_sensor);
@@ -1558,13 +1708,6 @@ static const int pmbus_fan_registers[] = {
 	PMBUS_READ_FAN_SPEED_4
 };
 
-static const int pmbus_fan_config_registers[] = {
-	PMBUS_FAN_CONFIG_12,
-	PMBUS_FAN_CONFIG_12,
-	PMBUS_FAN_CONFIG_34,
-	PMBUS_FAN_CONFIG_34
-};
-
 static const int pmbus_fan_status_registers[] = {
 	PMBUS_STATUS_FAN_12,
 	PMBUS_STATUS_FAN_12,
@@ -1587,6 +1730,48 @@ static const u32 pmbus_fan_status_flags[] = {
 };
 
 /* Fans */
+static int pmbus_add_fan_ctrl(struct i2c_client *client,
+		struct pmbus_data *data, int index, int page, int id,
+		u8 config)
+{
+	struct pmbus_sensor *sensor;
+	int rv;
+
+	rv = _pmbus_read_word_data(client, page,
+				   pmbus_fan_command_registers[id]);
+	if (rv < 0)
+		return rv;
+
+	sensor = pmbus_add_sensor(data, "fan", "target", index, page,
+				  PMBUS_VIRT_FAN_TARGET_1 + id, PSC_FAN,
+				  true, false);
+
+	if (!sensor)
+		return -ENOMEM;
+
+	if (!((data->info->func[page] & PMBUS_HAVE_PWM12) ||
+			(data->info->func[page] & PMBUS_HAVE_PWM34)))
+		return 0;
+
+	sensor = pmbus_add_sensor(data, "pwm", NULL, index, page,
+				  PMBUS_VIRT_PWM_1 + id, PSC_PWM,
+				  true, false);
+
+	if (!sensor)
+		return -ENOMEM;
+
+	sensor = pmbus_add_sensor(data, "pwm", "enable", index, page,
+				  PMBUS_VIRT_PWM_ENABLE_1 + id, PSC_PWM,
+				  true, false);
+
+	if (!sensor)
+		return -ENOMEM;
+
+	sensor->convert = false;
+
+	return 0;
+}
+
 static int pmbus_add_fan_attributes(struct i2c_client *client,
 				    struct pmbus_data *data)
 {
@@ -1624,6 +1809,15 @@ static int pmbus_add_fan_attributes(struct i2c_client *client,
 					     PSC_FAN, true, true) == NULL)
 				return -ENOMEM;
 
+			/* Fan control */
+			if (pmbus_check_word_register(client, page,
+					pmbus_fan_command_registers[f])) {
+				ret = pmbus_add_fan_ctrl(client, data, index,
+							 page, f, regval);
+				if (ret < 0)
+					return ret;
+			}
+
 			/*
 			 * Each fan status register covers multiple fans,
 			 * so we have to do some magic.
-- 
2.11.0

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