hwmon: (pmbus/max16601) Determine and use number of populated phases

The MAX16601 can report the number of populated phases. Use this
information to only create sysfs attributes for populated phases.

Cc: Alex Qiu <xqiu@google.com>
Cc: Ugur Usug <Ugur.Usug@maximintegrated.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20210125185327.93282-1-linux@roeck-us.netReviewed-by: Alex Qiu <xqiu@google.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/max16601.rst

@@ -45,7 +45,7 @@ Sysfs entries
 
 The following attributes are supported.
 
-======================= =======================================================
+=============================== ===============================================
 in1_label			"vin1"
 in1_input			VCORE input voltage.
 in1_alarm			Input voltage alarm.
@@ -55,83 +55,44 @@ in2_input		VCORE output voltage.
 in2_alarm			Output voltage alarm.
 
 curr1_label			"iin1"
-curr1_input		VCORE input current, derived from duty cycle and output
-			current.
+curr1_input			VCORE input current, derived from duty cycle
+				and output current.
 curr1_max			Maximum input current.
 curr1_max_alarm			Current high alarm.
 
-curr2_label		"iin1.0"
-curr2_input		VCORE phase 0 input current.
-
-curr3_label		"iin1.1"
-curr3_input		VCORE phase 1 input current.
-
-curr4_label		"iin1.2"
-curr4_input		VCORE phase 2 input current.
-
-curr5_label		"iin1.3"
-curr5_input		VCORE phase 3 input current.
-
-curr6_label		"iin1.4"
-curr6_input		VCORE phase 4 input current.
-
-curr7_label		"iin1.5"
-curr7_input		VCORE phase 5 input current.
-
-curr8_label		"iin1.6"
-curr8_input		VCORE phase 6 input current.
-
-curr9_label		"iin1.7"
-curr9_input		VCORE phase 7 input current.
+curr[P+2]_label			"iin1.P"
+curr[P+2]_input			VCORE phase P input current.
 
-curr10_label		"iin2"
-curr10_input		VCORE input current, derived from sensor element.
+curr[N+2]_label			"iin2"
+curr[N+2]_input			VCORE input current, derived from sensor
+				element.
+				'N' is the number of enabled/populated phases.
 
-curr11_label		"iin3"
-curr11_input		VSA input current.
+curr[N+3]_label			"iin3"
+curr[N+3]_input			VSA input current.
 
-curr12_label		"iout1"
-curr12_input		VCORE output current.
-curr12_crit		Critical output current.
-curr12_crit_alarm	Output current critical alarm.
-curr12_max		Maximum output current.
-curr12_max_alarm	Output current high alarm.
+curr[N+4]_label			"iout1"
+curr[N+4]_input			VCORE output current.
+curr[N+4]_crit			Critical output current.
+curr[N+4]_crit_alarm		Output current critical alarm.
+curr[N+4]_max			Maximum output current.
+curr[N+4]_max_alarm		Output current high alarm.
 
-curr13_label		"iout1.0"
-curr13_input		VCORE phase 0 output current.
+curr[N+P+5]_label		"iout1.P"
+curr[N+P+5]_input		VCORE phase P output current.
 
-curr14_label		"iout1.1"
-curr14_input		VCORE phase 1 output current.
-
-curr15_label		"iout1.2"
-curr15_input		VCORE phase 2 output current.
-
-curr16_label		"iout1.3"
-curr16_input		VCORE phase 3 output current.
-
-curr17_label		"iout1.4"
-curr17_input		VCORE phase 4 output current.
-
-curr18_label		"iout1.5"
-curr18_input		VCORE phase 5 output current.
-
-curr19_label		"iout1.6"
-curr19_input		VCORE phase 6 output current.
-
-curr20_label		"iout1.7"
-curr20_input		VCORE phase 7 output current.
-
-curr21_label		"iout3"
-curr21_input		VSA output current.
-curr21_highest		Historical maximum VSA output current.
-curr21_reset_history	Write any value to reset curr21_highest.
-curr21_crit		Critical output current.
-curr21_crit_alarm	Output current critical alarm.
-curr21_max		Maximum output current.
-curr21_max_alarm	Output current high alarm.
+curr[2*N+5]_label		"iout3"
+curr[2*N+5]_input		VSA output current.
+curr[2*N+5]_highest		Historical maximum VSA output current.
+curr[2*N+5]_reset_history	Write any value to reset curr21_highest.
+curr[2*N+5]_crit		Critical output current.
+curr[2*N+5]_crit_alarm		Output current critical alarm.
+curr[2*N+5]_max			Maximum output current.
+curr[2*N+5]_max_alarm		Output current high alarm.
 
 power1_label			"pin1"
-power1_input		Input power, derived from duty cycle and output current.
+power1_input			Input power, derived from duty cycle and output
+				current.
 power1_alarm			Input power alarm.
 
 power2_label			"pin2"
@@ -156,4 +117,4 @@ temp6_crit		Critical high temperature.
 temp6_crit_alarm		Chip temperature critical high alarm.
 temp6_max			Maximum temperature.
 temp6_max_alarm			Chip temperature high alarm.
-======================= =======================================================
+=============================== ===============================================

drivers/hwmon/pmbus/max16601.c

@@ -31,6 +31,7 @@
 
 #include "pmbus.h"
 
+#define REG_DEFAULT_NUM_POP	0xc4
 #define REG_SETPT_DVID		0xd1
 #define  DAC_10MV_MODE		BIT(4)
 #define REG_IOUT_AVG_PK		0xee
@@ -40,6 +41,8 @@
 #define  CORE_RAIL_INDICATOR	BIT(7)
 #define REG_PHASE_REPORTING	0xf4
 
+#define MAX16601_NUM_PHASES	8
+
 struct max16601_data {
 	struct pmbus_driver_info info;
 	struct i2c_client *vsa;
@@ -195,6 +198,18 @@ static int max16601_identify(struct i2c_client *client,
 	else
 		info->vrm_version[0] = vr12;
 
+	reg = i2c_smbus_read_byte_data(client, REG_DEFAULT_NUM_POP);
+	if (reg < 0)
+		return reg;
+
+	/*
+	 * If REG_DEFAULT_NUM_POP returns 0, we don't know how many phases
+	 * are populated. Stick with the default in that case.
+	 */
+	reg &= 0x0f;
+	if (reg && reg <= MAX16601_NUM_PHASES)
+		info->phases[0] = reg;
+
 	return 0;
 }
 
@@ -216,7 +231,7 @@ static struct pmbus_driver_info max16601_info = {
 	.func[2] = PMBUS_HAVE_IIN | PMBUS_HAVE_STATUS_INPUT |
 		PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
 		PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP | PMBUS_PAGE_VIRTUAL,
-	.phases[0] = 8,
+	.phases[0] = MAX16601_NUM_PHASES,
 	.pfunc[0] = PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT | PMBUS_HAVE_TEMP,
 	.pfunc[1] = PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT,
 	.pfunc[2] = PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT | PMBUS_HAVE_TEMP,