hwmon: (pmbus) Add support for MPS mp2975 controller

Add support for mp295 device from Monolithic Power Systems, Inc. (MPS) vendor. This is a dual-loop, digital, multi-phase controller. This device:
- Supports two power rail.
- Provides 8 pulse-width modulations (PWMs), and can be configured up to 8-phase operation for rail 1 and up to 4-phase operation for rail 2.
- Supports two pages 0 and 1 for telemetry and also pages 2 and 3 for configuration.
- Can configured VOUT readout in direct or VID format and allows setting of different formats on rails 1 and 2. For VID the following protocols are available: VR13 mode with 5-mV DAC; VR13 mode with 10-mV DAC, IMVP9 mode with 5-mV DAC.

Signed-off-by Vadim Pasternak <[email protected]>

---
v3->v4
Comments pointed out by Guenter:
- Drop redundant 'return' from mp2975_identify_multiphase_rail2().
- Fix phases assignment in mp2975_set_phase_rail2().
- Fix range for the number of phases in mp2975_set_multiphase_rail2().
- Drop mp2975_set_multiphase_rail2, call instead directly mp2975_set_phase_rail2(), since the phases range is already validated for rail 2.
- Fix handling for the case of zero number of phases for rail 1 in mp2975_identify_multiphase(), which is valid case.
- Simplify logic for rail1 and rail2 setting handling in mp2975_identify_multiphase().
- Line length limit is now 100, but 'checkpatch' scripts is still consider it as error.

- Modify 'switch' statement in mp2975_current_sense_gain_get().
- Fix misspelled comment in mp2975_probe().
v1->v2
Comments pointed out by Guenter:
- Add doc fail to the patch#1 (it was sent as separate patch).
- Use standard define for VOUT mode format.
- Simplify logic in mp2975_read_phase().
- Simplify calculation of phase current in mp2975_read_phase().
- Modify return code handling in mp2975_read_word_data().
- Add missed error handling in mp2975_read_word_data().
- Drop 'fallthrough;' in mp2975_read_word_data().
- Handle error code in mp2975_identify_multiphase_rail2().
- Handle error code in mp2975_identify_multiphase().
- Drop 'goto' in mp2975_vout_per_rail_config_get() and mp2975_probe().

---
 Documentation/hwmon/mp2975.rst | 116 +++++++
 drivers/hwmon/pmbus/Kconfig    |   9 +
 drivers/hwmon/pmbus/Makefile   |   1 +
 drivers/hwmon/pmbus/mp2975.c   | 772 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 898 insertions(+)
 create mode 100644 Documentation/hwmon/mp2975.rst
 create mode 100644 drivers/hwmon/pmbus/mp2975.c

Documentation/hwmon/mp2975.rst new file +116 -0

new file mode 100644
index 000000000000..5b0609c62f48
@@ -0,0 +1,116 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver mp2975
+====================
+
+Supported chips:
+
+  * MPS MP12254
+
+    Prefix: 'mp2975'
+
+Author:
+
+	Vadim Pasternak <[email protected]>
+
+Description
+-----------
+
+This driver implements support for Monolithic Power Systems, Inc. (MPS)
+vendor dual-loop, digital, multi-phase controller MP2975.
+
+This device:
+- Supports up to two power rail.
+- Provides 8 pulse-width modulations (PWMs), and can be configured up
+  to 8-phase operation for rail 1 and up to 4-phase operation for rail
+  2.
+- Supports two pages 0 and 1 for telemetry and also pages 2 and 3 for
+  configuration.
+- Can configured VOUT readout in direct or VID format and allows
+  setting of different formats on rails 1 and 2. For VID the following
+  protocols are available: VR13 mode with 5-mV DAC; VR13 mode with
+  10-mV DAC, IMVP9 mode with 5-mV DAC.
+
+Device supports:
+- SVID interface.
+- AVSBus interface.
+
+Device complaint with:
+- PMBus rev 1.3 interface.
+
+Device supports direct format for reading output current, output voltage,
+input and output power and temperature.
+Device supports linear format for reading input voltage and input power.
+Device supports VID and direct formats for reading output voltage.
+The below VID modes are supported: VR12, VR13, IMVP9.
+
+The driver provides the next attributes for the current:
+- for current in: input, maximum alarm;
+- for current out input, maximum alarm and highest values;
+- for phase current: input and label.
+attributes.
+The driver exports the following attributes via the 'sysfs' files, where
+- 'n' is number of telemetry pages (from 1 to 2);
+- 'k' is number of configured phases (from 1 to 8);
+- indexes 1, 1*n for "iin";
+- indexes n+1, n+2 for "iout";
+- indexes 2*n+1 ... 2*n + k for phases.
+
+**curr[1-{2n}]_alarm**
+
+**curr[{n+1}-{n+2}]_highest**
+
+**curr[1-{2n+k}]_input**
+
+**curr[1-{2n+k}]_label**
+
+The driver provides the next attributes for the voltage:
+- for voltage in: input, high critical threshold, high critical alarm, all only
+  from page 0;
+- for voltage out: input, low and high critical thresholds, low and high
+  critical alarms, from pages 0 and 1;
+The driver exports the following attributes via the 'sysfs' files, where
+- 'n' is number of telemetry pages (from 1 to 2);
+- indexes 1 for "iin";
+- indexes n+1, n+2 for "vout";
+
+**in[1-{2n+1}]_crit**
+
+**in[1-{2n+1}]_crit_alarm**
+
+**in[1-{2n+1}]_input**
+
+**in[1-{2n+1}]_label**
+
+**in[2-{n+1}]_lcrit**
+
+**in[2-{n+1}1_lcrit_alarm**
+
+The driver provides the next attributes for the power:
+- for power in alarm and input.
+- for power out: highest and input.
+The driver exports the following attributes via the 'sysfs' files, where
+- 'n' is number of telemetry pages (from 1 to 2);
+- indexes 1 for "pin";
+- indexes n+1, n+2 for "pout";
+
+**power1_alarm**
+
+**power[2-{n+1}]_highest**
+
+**power[1-{2n+1}]_input**
+
+**power[1-{2n+1}]_label**
+
+The driver provides the next attributes for the temperature (only from page 0):
+
+
+**temp1_crit**
+
+**temp1_crit_alarm**
+
+**temp1_input**
+
+**temp1_max**
+
+**temp1_max_alarm**

drivers/hwmon/pmbus/Kconfig +9 -0

index e35db489b76f..1e6157e85437 100644
@@ -200,6 +200,15 @@ config SENSORS_MAX8688
 	  This driver can also be built as a module. If so, the module will
 	  be called max8688.
 
+config SENSORS_MP2975
+	tristate "MPS MP2975"
+	help
+	  If you say yes here you get hardware monitoring support for MPS
+	  MP2975 Dual Loop Digital Multi-Phase Controller.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called mp2975.
+
 config SENSORS_PXE1610
 	tristate "Infineon PXE1610"
 	help

drivers/hwmon/pmbus/Makefile +1 -0

index c4b15db996ad..0e2832e73cfc 100644
@@ -23,6 +23,7 @@ obj-$(CONFIG_SENSORS_MAX20751)	+= max20751.o
 obj-$(CONFIG_SENSORS_MAX31785)	+= max31785.o
 obj-$(CONFIG_SENSORS_MAX34440)	+= max34440.o
 obj-$(CONFIG_SENSORS_MAX8688)	+= max8688.o
+obj-$(CONFIG_SENSORS_MP2975)	+= mp2975.o
 obj-$(CONFIG_SENSORS_PXE1610)	+= pxe1610.o
 obj-$(CONFIG_SENSORS_TPS40422)	+= tps40422.o
 obj-$(CONFIG_SENSORS_TPS53679)	+= tps53679.o

drivers/hwmon/pmbus/mp2975.c new file +594 -0

new file mode 100644
index 000000000000..f2f3e74c4953
@@ -0,0 +1,772 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Hardware monitoring driver for MPS Multi-phase Digital VR Controllers
+ *
+ * Copyright (C) 2020 Nvidia Technologies Ltd.
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include "pmbus.h"
+
+/* Vendor specific registers. */
+#define MP2975_MFR_APS_HYS_R2		0x0d
+#define MP2975_MFR_SLOPE_TRIM3		0x1d
+#define MP2975_MFR_VR_MULTI_CONFIG_R1	0x0d
+#define MP2975_MFR_VR_MULTI_CONFIG_R2	0x1d
+#define MP2975_MFR_APS_DECAY_ADV	0x56
+#define MP2975_MFR_DC_LOOP_CTRL		0x59
+#define MP2975_MFR_OCP_UCP_PHASE_SET	0x65
+#define MP2975_MFR_VR_CONFIG1		0x68
+#define MP2975_MFR_READ_CS1_2		0x82
+#define MP2975_MFR_READ_CS3_4		0x83
+#define MP2975_MFR_READ_CS5_6		0x84
+#define MP2975_MFR_READ_CS7_8		0x85
+#define MP2975_MFR_READ_CS9_10		0x86
+#define MP2975_MFR_READ_CS11_12		0x87
+#define MP2975_MFR_READ_IOUT_PK		0x90
+#define MP2975_MFR_READ_POUT_PK		0x91
+#define MP2975_MFR_READ_VREF_R1		0xa1
+#define MP2975_MFR_READ_VREF_R2		0xa3
+#define MP2975_MFR_OVP_TH_SET		0xe5
+#define MP2975_MFR_UVP_SET		0xe6
+
+#define MP2975_VOUT_FORMAT		BIT(15)
+#define MP2975_VID_STEP_SEL_R1		BIT(4)
+#define MP2975_IMVP9_EN_R1		BIT(13)
+#define MP2975_VID_STEP_SEL_R2		BIT(3)
+#define MP2975_IMVP9_EN_R2		BIT(12)
+#define MP2975_PRT_THRES_DIV_OV_EN	BIT(14)
+#define MP2975_DRMOS_KCS		GENMASK(13, 12)
+#define MP2975_PROT_DEV_OV_OFF		10
+#define MP2975_PROT_DEV_OV_ON		5
+#define MP2975_SENSE_AMPL		BIT(11)
+#define MP2975_SENSE_AMPL_UNIT		1
+#define MP2975_SENSE_AMPL_HALF		2
+#define MP2975_VIN_UV_LIMIT_UNIT	8
+
+#define MP2975_MAX_PHASE_RAIL1	8
+#define MP2975_MAX_PHASE_RAIL2	4
+#define MP2975_PAGE_NUM		2
+
+#define MP2975_RAIL2_FUNC	(PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT | \
+				 PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT | \
+				 PMBUS_PHASE_VIRTUAL)
+
+struct mp2975_data {
+	struct pmbus_driver_info info;
+	int vout_scale;
+	int vid_step[MP2975_PAGE_NUM];
+	int vref[MP2975_PAGE_NUM];
+	int vref_off[MP2975_PAGE_NUM];
+	int vout_max[MP2975_PAGE_NUM];
+	int vout_ov_fixed[MP2975_PAGE_NUM];
+	int vout_format[MP2975_PAGE_NUM];
+	int curr_sense_gain[MP2975_PAGE_NUM];
+};
+
+#define to_mp2975_data(x)  container_of(x, struct mp2975_data, info)
+
+static int mp2975_read_byte_data(struct i2c_client *client, int page, int reg)
+{
+	switch (reg) {
+	case PMBUS_VOUT_MODE:
+		/*
+		 * Enforce VOUT direct format, since device allows to set the
+		 * different formats for the different rails. Conversion from
+		 * VID to direct provided by driver internally, in case it is
+		 * necessary.
+		 */
+		return PB_VOUT_MODE_DIRECT;
+	default:
+		return -ENODATA;
+	}
+}
+
+static int
+mp2975_read_word_helper(struct i2c_client *client, int page, int phase, u8 reg,
+			u16 mask)
+{
+	int ret = pmbus_read_word_data(client, page, phase, reg);
+
+	return (ret > 0) ? ret & mask : ret;
+}
+
+static int
+mp2975_vid2direct(int vrf, int val)
+{
+	switch (vrf) {
+	case vr12:
+		if (val >= 0x01)
+			return 250 + (val - 1) * 5;
+		break;
+	case vr13:
+		if (val >= 0x01)
+			return 500 + (val - 1) * 10;
+		break;
+	case imvp9:
+		if (val >= 0x01)
+			return 200 + (val - 1) * 10;
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int
+mp2975_read_phase(struct i2c_client *client, struct mp2975_data *data,
+		  int page, int phase, u8 reg)
+{
+	int ph_curr, ret;
+
+	ret = pmbus_read_word_data(client, page, phase, reg);
+	if (ret < 0)
+		return ret;
+
+	if (!((phase + 1) % MP2975_PAGE_NUM))
+		ret >>= 8;
+	ret &= 0xff;
+
+	/*
+	 * Output value is calculated as: (READ_CSx / 80 – 1.23) / (Kcs * Rcs)
+	 * where:
+	 * - Kcs is the DrMOS current sense gain of power stage, which is
+	 *   obtained from the register MP2975_MFR_VR_CONFIG1, bits 13-12 with
+	 *   the following selection of DrMOS (data->curr_sense_gain[page]):
+	 *   00b - 5µA/A, 01b - 8.5µA/A, 10b - 9.7µA/A, 11b - 10µA/A.
+	 * - Rcs is the internal phase current sense resistor which is constant
+	 *   value 1kΩ.
+	 */
+	ph_curr = ret * 100 - 9800;
+
+	/*
+	 * Current phase sensing, providing by the device is not accurate
+	 * for the light load. This because sampling of current occurrence of
+	 * bit weight has a big deviation for light load. For handling such
+	 * case phase current is represented as the maximum between the value
+	 * calculated  above and total rail current divided by number phases.
+	 */
+	ret = pmbus_read_word_data(client, page, phase, PMBUS_READ_IOUT);
+	if (ret < 0)
+		return ret;
+
+	return max_t(int, DIV_ROUND_CLOSEST(ret, data->info.phases[page]),
+		     DIV_ROUND_CLOSEST(ph_curr, data->curr_sense_gain[page]));
+}
+
+static int
+mp2975_read_phases(struct i2c_client *client, struct mp2975_data *data,
+		   int page, int phase)
+{
+	int ret;
+
+	if (page) {
+		switch (phase) {
+		case 0 ... 1:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS7_8);
+			break;
+		case 2 ... 3:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS9_10);
+			break;
+		case 4 ... 5:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS11_12);
+			break;
+		default:
+			return -ENODATA;
+		}
+	} else {
+		switch (phase) {
+		case 0 ... 1:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS1_2);
+			break;
+		case 2 ... 3:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS3_4);
+			break;
+		case 4 ... 5:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS5_6);
+			break;
+		case 6 ... 7:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS7_8);
+			break;
+		case 8 ... 9:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS9_10);
+			break;
+		case 10 ... 11:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS11_12);
+			break;
+		default:
+			return -ENODATA;
+		}
+	}
+	return ret;
+}
+
+static int mp2975_read_word_data(struct i2c_client *client, int page,
+				 int phase, int reg)
+{
+	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+	struct mp2975_data *data = to_mp2975_data(info);
+	int ret;
+
+	switch (reg) {
+	case PMBUS_OT_FAULT_LIMIT:
+		ret = mp2975_read_word_helper(client, page, phase, reg,
+					      GENMASK(7, 0));
+		break;
+	case PMBUS_VIN_OV_FAULT_LIMIT:
+		ret = mp2975_read_word_helper(client, page, phase, reg,
+					      GENMASK(7, 0));
+		if (ret < 0)
+			return ret;
+
+		ret = DIV_ROUND_CLOSEST(ret, MP2975_VIN_UV_LIMIT_UNIT);
+		break;
+	case PMBUS_VOUT_OV_FAULT_LIMIT:
+		/*
+		 * Register provides two values for over-voltage protection
+		 * threshold for fixed (ovp2) and tracking (ovp1) modes. The
+		 * minimum of these two values is provided as over-voltage
+		 * fault alarm.
+		 */
+		ret = mp2975_read_word_helper(client, page, phase,
+					      MP2975_MFR_OVP_TH_SET,
+					      GENMASK(2, 0));
+		if (ret < 0)
+			return ret;
+
+		ret = min_t(int, data->vout_max[page] + 50 * (ret + 1),
+			    data->vout_ov_fixed[page]);
+		break;
+	case PMBUS_VOUT_UV_FAULT_LIMIT:
+		ret = mp2975_read_word_helper(client, page, phase,
+					      MP2975_MFR_UVP_SET,
+					      GENMASK(2, 0));
+		if (ret < 0)
+			return ret;
+
+		ret = DIV_ROUND_CLOSEST(data->vref[page] * 10 - 50 *
+					(ret + 1) * data->vout_scale, 10);
+		break;
+	case PMBUS_READ_VOUT:
+		ret = mp2975_read_word_helper(client, page, phase, reg,
+					      GENMASK(11, 0));
+		if (ret < 0)
+			return ret;
+
+		/*
+		 * READ_VOUT can be provided in VID or direct format. The
+		 * format type is specified by bit 15 of the register
+		 * MP2975_MFR_DC_LOOP_CTRL. The driver enforces VOUT direct
+		 * format, since device allows to set the different formats for
+		 * the different rails and also all VOUT limits registers are
+		 * provided in a direct format. In case format is VID - convert
+		 * to direct.
+		 */
+		if (data->vout_format[page] == vid)
+			ret = mp2975_vid2direct(info->vrm_version[page], ret);
+		break;
+	case PMBUS_VIRT_READ_POUT_MAX:
+		ret = mp2975_read_word_helper(client, page, phase,
+					      MP2975_MFR_READ_POUT_PK,
+					      GENMASK(12, 0));
+		if (ret < 0)
+			return ret;
+
+		ret = DIV_ROUND_CLOSEST(ret, 4);
+		break;
+	case PMBUS_VIRT_READ_IOUT_MAX:
+		ret = mp2975_read_word_helper(client, page, phase,
+					      MP2975_MFR_READ_IOUT_PK,
+					      GENMASK(12, 0));
+		if (ret < 0)
+			return ret;
+
+		ret = DIV_ROUND_CLOSEST(ret, 4);
+		break;
+	case PMBUS_READ_IOUT:
+		ret = mp2975_read_phases(client, data, page, phase);
+		if (ret < 0)
+			return ret;
+
+		break;
+	case PMBUS_UT_WARN_LIMIT:
+	case PMBUS_UT_FAULT_LIMIT:
+	case PMBUS_VIN_UV_WARN_LIMIT:
+	case PMBUS_VIN_UV_FAULT_LIMIT:
+	case PMBUS_VOUT_UV_WARN_LIMIT:
+	case PMBUS_VOUT_OV_WARN_LIMIT:
+	case PMBUS_VIN_OV_WARN_LIMIT:
+	case PMBUS_IIN_OC_FAULT_LIMIT:
+	case PMBUS_IOUT_OC_LV_FAULT_LIMIT:
+	case PMBUS_IIN_OC_WARN_LIMIT:
+	case PMBUS_IOUT_OC_WARN_LIMIT:
+	case PMBUS_IOUT_OC_FAULT_LIMIT:
+	case PMBUS_IOUT_UC_FAULT_LIMIT:
+	case PMBUS_POUT_OP_FAULT_LIMIT:
+	case PMBUS_POUT_OP_WARN_LIMIT:
+	case PMBUS_PIN_OP_WARN_LIMIT:
+		return -ENXIO;
+	default:
+		return -ENODATA;
+	}
+
+	return ret;
+}
+
+static int mp2975_identify_multiphase_rail2(struct i2c_client *client)
+{
+	int ret;
+
+	/*
+	 * Identify multiphase for rail 2 - could be from 0 to 4.
+	 * In case phase number is zero – only page zero is supported
+	 */
+	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
+	if (ret < 0)
+		return ret;
+
+	/* Identify multiphase for rail 2 - could be from 0 to 4. */
+	ret = i2c_smbus_read_word_data(client, MP2975_MFR_VR_MULTI_CONFIG_R2);
+	if (ret < 0)
+		return ret;
+
+	ret &= GENMASK(2, 0);
+	return (ret >= 4) ? 4 : ret;
+}
+
+static void mp2975_set_phase_rail1(struct pmbus_driver_info *info)
+{
+	int i;
+
+	for (i = 0 ; i < info->phases[0]; i++)
+		info->pfunc[i] = PMBUS_HAVE_IOUT;
+}
+
+static void
+mp2975_set_phase_rail2(struct pmbus_driver_info *info, int num_phases)
+{
+	int i;
+
+	/* Set phases for rail 2 from upper to lower. */
+	for (i = 1; i <= num_phases; i++)
+		info->pfunc[MP2975_MAX_PHASE_RAIL1 - i] = PMBUS_HAVE_IOUT;
+}
+
+static int
+mp2975_identify_multiphase(struct i2c_client *client, struct mp2975_data *data,
+			   struct pmbus_driver_info *info)
+{
+	int num_phases2, ret;
+
+	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
+	if (ret < 0)
+		return ret;
+
+	/* Identify multiphase for rail 1 - could be from 1 to 8. */
+	ret = i2c_smbus_read_word_data(client, MP2975_MFR_VR_MULTI_CONFIG_R1);
+	if (ret <= 0)
+		return ret;
+
+	info->phases[0] = ret & GENMASK(3, 0);
+
+	/*
+	 * The device provides a total of 8 PWM pins, and can be configured
+	 * to different phase count applications for rail 1 and rail 2.
+	 * Rail 1 can be set to 8 phases, while rail 2 can only be set to 4
+	 * phases at most. When rail 1’s phase count is configured as 0, rail
+	 * 1 operates with 1-phase DCM. When rail 2 phase count is configured
+	 * as 0, rail 2 is disabled.
+	 */
+	if (info->phases[0] > MP2975_MAX_PHASE_RAIL1)
+		return -EINVAL;
+
+	mp2975_set_phase_rail1(info);
+	num_phases2 = min(MP2975_MAX_PHASE_RAIL1 - info->phases[0],
+			  MP2975_MAX_PHASE_RAIL2);
+	if (info->phases[1] && info->phases[1] <= num_phases2)
+		mp2975_set_phase_rail2(info, num_phases2);
+
+	return 0;
+}
+
+static int
+mp2975_identify_vid(struct i2c_client *client, struct mp2975_data *data,
+		    struct pmbus_driver_info *info, u32 reg, int page,
+		    u32 imvp_bit, u32 vr_bit)
+{
+	int ret;
+
+	/* Identify VID mode and step selection. */
+	ret = i2c_smbus_read_word_data(client, reg);
+	if (ret < 0)
+		return ret;
+
+	if (ret & imvp_bit) {
+		info->vrm_version[page] = imvp9;
+		data->vid_step[page] = MP2975_PROT_DEV_OV_OFF;
+	} else if (ret & vr_bit) {
+		info->vrm_version[page] = vr12;
+		data->vid_step[page] = MP2975_PROT_DEV_OV_ON;
+	} else {
+		info->vrm_version[page] = vr13;
+		data->vid_step[page] = MP2975_PROT_DEV_OV_OFF;
+	}
+
+	return 0;
+}
+
+static int
+mp2975_identify_rails_vid(struct i2c_client *client, struct mp2975_data *data,
+			  struct pmbus_driver_info *info)
+{
+	int ret;
+
+	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
+	if (ret < 0)
+		return ret;
+
+	/* Identify VID mode for rail 1. */
+	ret = mp2975_identify_vid(client, data, info,
+				  MP2975_MFR_VR_MULTI_CONFIG_R1, 0,
+				  MP2975_IMVP9_EN_R1, MP2975_VID_STEP_SEL_R1);
+	if (ret < 0)
+		return ret;
+
+	/* Identify VID mode for rail 2, if connected. */
+	if (info->phases[1])
+		ret = mp2975_identify_vid(client, data, info,
+					  MP2975_MFR_VR_MULTI_CONFIG_R2, 1,
+					  MP2975_IMVP9_EN_R2,
+					  MP2975_VID_STEP_SEL_R2);
+	return ret;
+}
+
+static int
+mp2975_current_sense_gain_get(struct i2c_client *client,
+			      struct mp2975_data *data)
+{
+	int i, ret;
+
+	/*
+	 * Obtain DrMOS current sense gain of power stage from the register
+	 * MP2975_MFR_VR_CONFIG1, bits 13-12. The value is selected as below:
+	 * 00b - 5µA/A, 01b - 8.5µA/A, 10b - 9.7µA/A, 11b - 10µA/A. Other
+	 * values are invalid.
+	 */
+	for (i = 0 ; i < data->info.pages; i++) {
+		ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, i);
+		if (ret < 0)
+			return ret;
+		ret = i2c_smbus_read_word_data(client,
+					       MP2975_MFR_VR_CONFIG1);
+		if (ret < 0)
+			return ret;
+
+		switch ((ret & MP2975_DRMOS_KCS) >> 12) {
+		case 0:
+			data->curr_sense_gain[i] = 50;
+			break;
+		case 1:
+			data->curr_sense_gain[i] = 85;
+			break;
+		case 2:
+			data->curr_sense_gain[i] = 97;
+			break;
+		default:
+			data->curr_sense_gain[i] = 100;
+			break;
+		}
+	}
+
+	return 0;
+}
+
+static int
+mp2975_vref_get(struct i2c_client *client, struct mp2975_data *data,
+		struct pmbus_driver_info *info)
+{
+	int ret;
+
+	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 3);
+	if (ret < 0)
+		return ret;
+
+	/* Get voltage reference value for rail 1. */
+	ret = i2c_smbus_read_word_data(client, MP2975_MFR_READ_VREF_R1);
+	if (ret < 0)
+		return ret;
+
+	data->vref[0] = ret * data->vid_step[0];
+
+	/* Get voltage reference value for rail 2, if connected. */
+	if (data->info.pages == MP2975_PAGE_NUM) {
+		ret = i2c_smbus_read_word_data(client, MP2975_MFR_READ_VREF_R2);
+		if (ret < 0)
+			return ret;
+
+		data->vref[1] = ret * data->vid_step[1];
+	}
+	return 0;
+}
+
+static int
+mp2975_vref_offset_get(struct i2c_client *client, struct mp2975_data *data,
+		       int page)
+{
+	int ret;
+
+	ret = i2c_smbus_read_word_data(client, MP2975_MFR_OVP_TH_SET);
+	if (ret < 0)
+		return ret;
+
+	switch ((ret & GENMASK(5, 3)) >> 3) {
+	case 1:
+		data->vref_off[page] = 140;
+		break;
+	case 2:
+		data->vref_off[page] = 220;
+		break;
+	case 4:
+		data->vref_off[page] = 400;
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int
+mp2975_vout_max_get(struct i2c_client *client, struct mp2975_data *data,
+		    struct pmbus_driver_info *info, int page)
+{
+	int ret;
+
+	/* Get maximum reference voltage of VID-DAC in VID format. */
+	ret = i2c_smbus_read_word_data(client, PMBUS_VOUT_MAX);
+	if (ret < 0)
+		return ret;
+
+	data->vout_max[page] = mp2975_vid2direct(info->vrm_version[page], ret &
+						 GENMASK(8, 0));
+	return 0;
+}
+
+static int
+mp2975_identify_vout_format(struct i2c_client *client,
+			    struct mp2975_data *data, int page)
+{
+	int ret;
+
+	ret = i2c_smbus_read_word_data(client, MP2975_MFR_DC_LOOP_CTRL);
+	if (ret < 0)
+		return ret;
+
+	if (ret & MP2975_VOUT_FORMAT)
+		data->vout_format[page] = vid;
+	else
+		data->vout_format[page] = direct;
+	return 0;
+}
+
+static int
+mp2975_vout_ov_scale_get(struct i2c_client *client, struct mp2975_data *data,
+			 struct pmbus_driver_info *info)
+{
+	int thres_dev, sense_ampl, ret;
+
+	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 0);
+	if (ret < 0)
+		return ret;
+
+	/*

drivers/hwmon/pmbus/mp2975.c new file +160 -0

+
+	data->vout_scale = sense_ampl * thres_dev;
+
+	return 0;
+}
+
+static int
+mp2975_vout_per_rail_config_get(struct i2c_client *client,
+				struct mp2975_data *data,
+				struct pmbus_driver_info *info)
+{
+	int i, ret;
+
+	for (i = 0; i < data->info.pages; i++) {
+		ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, i);
+		if (ret < 0)
+			return ret;
+
+		/* Obtain voltage reference offsets. */
+		ret = mp2975_vref_offset_get(client, data, i);
+		if (ret < 0)
+			return ret;
+
+		/* Obtain maximum voltage values. */
+		ret = mp2975_vout_max_get(client, data, info, i);
+		if (ret < 0)
+			return ret;
+
+		/*
+		 * Get VOUT format for READ_VOUT command : VID or direct.
+		 * Pages on same device can be configured with different
+		 * formats.
+		 */
+		ret = mp2975_identify_vout_format(client, data, i);
+		if (ret < 0)
+			return ret;
+
+		/*
+		 * Set over-voltage fixed value. Thresholds are provided as
+		 * fixed value, and tracking value. The minimum of them are
+		 * exposed as over-voltage critical threshold.
+		 */
+		data->vout_ov_fixed[i] = data->vref[i] +
+					 DIV_ROUND_CLOSEST(data->vref_off[i] *
+							   data->vout_scale,
+							   10);
+	}
+
+	return 0;
+}
+
+static struct pmbus_driver_info mp2975_info = {
+	.pages = 1,
+	.format[PSC_VOLTAGE_IN] = linear,
+	.format[PSC_VOLTAGE_OUT] = direct,
+	.format[PSC_TEMPERATURE] = direct,
+	.format[PSC_CURRENT_IN] = linear,
+	.format[PSC_CURRENT_OUT] = direct,
+	.format[PSC_POWER] = direct,
+	.m[PSC_TEMPERATURE] = 1,
+	.m[PSC_VOLTAGE_OUT] = 1,
+	.R[PSC_VOLTAGE_OUT] = 3,
+	.m[PSC_CURRENT_OUT] = 1,
+	.m[PSC_POWER] = 1,
+	.func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT |
+		PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
+		PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP | PMBUS_HAVE_POUT |
+		PMBUS_HAVE_PIN | PMBUS_HAVE_STATUS_INPUT | PMBUS_PHASE_VIRTUAL,
+	.read_byte_data = mp2975_read_byte_data,
+	.read_word_data = mp2975_read_word_data,
+};
+
+static int mp2975_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	struct pmbus_driver_info *info;
+	struct mp2975_data *data;
+	int ret;
+
+	data = devm_kzalloc(&client->dev, sizeof(struct mp2975_data),
+			    GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	memcpy(&data->info, &mp2975_info, sizeof(*info));
+	info = &data->info;
+
+	/* Identify multiphase configuration for rail 2. */
+	ret = mp2975_identify_multiphase_rail2(client);
+	if (ret < 0)
+		return ret;
+
+	if (ret) {
+		/* Two rails are connected. */
+		data->info.pages = MP2975_PAGE_NUM;
+		data->info.phases[1] = ret;
+		data->info.func[1] = MP2975_RAIL2_FUNC;
+	}
+
+	/* Identify multiphase configuration. */
+	ret = mp2975_identify_multiphase(client, data, info);
+	if (ret)
+		return ret;
+
+	/* Identify VID setting per rail. */
+	ret = mp2975_identify_rails_vid(client, data, info);
+	if (ret < 0)
+		return ret;
+
+	/* Obtain current sense gain of power stage. */
+	ret = mp2975_current_sense_gain_get(client, data);
+	if (ret)
+		return ret;
+
+	/* Obtain voltage reference values. */
+	ret = mp2975_vref_get(client, data, info);
+	if (ret)
+		return ret;
+
+	/* Obtain vout over-voltage scales. */
+	ret = mp2975_vout_ov_scale_get(client, data, info);
+	if (ret < 0)
+		return ret;
+
+	/* Obtain offsets, maximum and format for vout. */
+	ret = mp2975_vout_per_rail_config_get(client, data, info);
+	if (ret)
+		return ret;
+
+	return pmbus_do_probe(client, id, info);
+}
+
+static const struct i2c_device_id mp2975_id[] = {
+	{"mp2975", 0},
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, mp2975_id);
+
+static const struct of_device_id __maybe_unused mp2975_of_match[] = {
+	{.compatible = "mps,mp2975"},
+	{}
+};
+MODULE_DEVICE_TABLE(of, mp2975_of_match);
+
+static struct i2c_driver mp2975_driver = {
+	.driver = {
+		.name = "mp2975",
+		.of_match_table = of_match_ptr(mp2975_of_match),
+	},
+	.probe = mp2975_probe,
+	.remove = pmbus_do_remove,
+	.id_table = mp2975_id,
+};
+
+module_i2c_driver(mp2975_driver);
+
+MODULE_AUTHOR("Vadim Pasternak <[email protected]>");
+MODULE_DESCRIPTION("PMBus driver for MPS MP2975 device");
+MODULE_LICENSE("GPL");

-----Original Message-----
From: Guenter Roeck <[email protected]> On Behalf Of Guenter Roeck
Sent: Wednesday, September 30, 2020 8:17 AM
To: Vadim Pasternak <[email protected]>
Cc: [email protected]; [email protected]; [email protected]
Subject: Re: [PATCH hwmon-next v4 1/2] hwmon: (pmbus) Add support for MPS Multi-phase mp2975 controller

Quoted 15 lines · Vadim Pasternak

Add support for mp295 device from Monolithic Power Systems, Inc. (MPS) vendor. This is a dual-loop, digital, multi-phase controller. This device:
- Supports two power rail.
- Provides 8 pulse-width modulations (PWMs), and can be configured up to 8-phase operation for rail 1 and up to 4-phase operation for rail 2.
- Supports two pages 0 and 1 for telemetry and also pages 2 and 3 for configuration.
- Can configured VOUT readout in direct or VID format and allows setting of different formats on rails 1 and 2. For VID the following protocols are available: VR13 mode with 5-mV DAC; VR13 mode with 10-mV DAC, IMVP9 mode with 5-mV DAC.

Signed-off-by Vadim Pasternak <[email protected]>

Quoted 15 lines

---
v3->v4
Comments pointed out by Guenter:
- Drop redundant 'return' from mp2975_identify_multiphase_rail2().
- Fix phases assignment in mp2975_set_phase_rail2().
- Fix range for the number of phases in mp2975_set_multiphase_rail2().
- Drop mp2975_set_multiphase_rail2, call instead directly mp2975_set_phase_rail2(), since the phases range is already validated for rail 2.
- Fix handling for the case of zero number of phases for rail 1 in mp2975_identify_multiphase(), which is valid case.
- Simplify logic for rail1 and rail2 setting handling in mp2975_identify_multiphase().
- Line length limit is now 100, but 'checkpatch' scripts is still consider it as error.

Not really. That only happens if your baseline kernel version is too old. ee upstream commit bdc48fa11e46 ("checkpatch/coding-style: deprecate 80- column warning").

Quoted 15 lines

- Modify 'switch' statement in mp2975_current_sense_gain_get().
- Fix misspelled comment in mp2975_probe().
v1->v2
Comments pointed out by Guenter:
- Add doc fail to the patch#1 (it was sent as separate patch).
- Use standard define for VOUT mode format.
- Simplify logic in mp2975_read_phase().
- Simplify calculation of phase current in mp2975_read_phase().
- Modify return code handling in mp2975_read_word_data().
- Add missed error handling in mp2975_read_word_data().
- Drop 'fallthrough;' in mp2975_read_word_data().
- Handle error code in mp2975_identify_multiphase_rail2().
- Handle error code in mp2975_identify_multiphase().
- Drop 'goto' in mp2975_vout_per_rail_config_get() and mp2975_probe().

Quoted 5 lines

---
 Documentation/hwmon/mp2975.rst | 116 +++++++
 drivers/hwmon/pmbus/Kconfig    |   9 +
 drivers/hwmon/pmbus/Makefile   |   1 +
 drivers/hwmon/pmbus/mp2975.c   | 772

+++++++++++++++++++++++++++++++++++++++++

Quoted 2 lines

 4 files changed, 898 insertions(+)
 create mode 100644 Documentation/hwmon/mp2975.rst  create mode

100644

Quoted 109 lines

drivers/hwmon/pmbus/mp2975.c

(quoted diff) +0 -0

b/Documentation/hwmon/mp2975.rst new file mode 100644 index 000000000000..5b0609c62f48

Documentation/hwmon/mp2975.rst new file +101 -0

@@ -0,0 +1,116 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver mp2975
+====================
+
+Supported chips:
+
+  * MPS MP12254
+
+    Prefix: 'mp2975'
+
+Author:
+
+	Vadim Pasternak <[email protected]>
+
+Description
+-----------
+
+This driver implements support for Monolithic Power Systems, Inc.
+(MPS) vendor dual-loop, digital, multi-phase controller MP2975.
+
+This device:
+- Supports up to two power rail.
+- Provides 8 pulse-width modulations (PWMs), and can be configured up
+  to 8-phase operation for rail 1 and up to 4-phase operation for
+rail
+  2.
+- Supports two pages 0 and 1 for telemetry and also pages 2 and 3 for
+  configuration.
+- Can configured VOUT readout in direct or VID format and allows
+  setting of different formats on rails 1 and 2. For VID the
+following
+  protocols are available: VR13 mode with 5-mV DAC; VR13 mode with
+  10-mV DAC, IMVP9 mode with 5-mV DAC.
+
+Device supports:
+- SVID interface.
+- AVSBus interface.
+
+Device complaint with:
+- PMBus rev 1.3 interface.
+
+Device supports direct format for reading output current, output
+voltage, input and output power and temperature.
+Device supports linear format for reading input voltage and input power.
+Device supports VID and direct formats for reading output voltage.
+The below VID modes are supported: VR12, VR13, IMVP9.
+
+The driver provides the next attributes for the current:
+- for current in: input, maximum alarm;
+- for current out input, maximum alarm and highest values;
+- for phase current: input and label.
+attributes.
+The driver exports the following attributes via the 'sysfs' files,
+where
+- 'n' is number of telemetry pages (from 1 to 2);
+- 'k' is number of configured phases (from 1 to 8);
+- indexes 1, 1*n for "iin";
+- indexes n+1, n+2 for "iout";
+- indexes 2*n+1 ... 2*n + k for phases.
+
+**curr[1-{2n}]_alarm**
+
+**curr[{n+1}-{n+2}]_highest**
+
+**curr[1-{2n+k}]_input**
+
+**curr[1-{2n+k}]_label**
+
+The driver provides the next attributes for the voltage:
+- for voltage in: input, high critical threshold, high critical
+alarm, all only
+  from page 0;
+- for voltage out: input, low and high critical thresholds, low and
+high
+  critical alarms, from pages 0 and 1; The driver exports the
+following attributes via the 'sysfs' files, where
+- 'n' is number of telemetry pages (from 1 to 2);
+- indexes 1 for "iin";
+- indexes n+1, n+2 for "vout";
+
+**in[1-{2n+1}]_crit**
+
+**in[1-{2n+1}]_crit_alarm**
+
+**in[1-{2n+1}]_input**
+
+**in[1-{2n+1}]_label**
+
+**in[2-{n+1}]_lcrit**
+
+**in[2-{n+1}1_lcrit_alarm**
+
+The driver provides the next attributes for the power:
+- for power in alarm and input.
+- for power out: highest and input.
+The driver exports the following attributes via the 'sysfs' files,
+where
+- 'n' is number of telemetry pages (from 1 to 2);
+- indexes 1 for "pin";
+- indexes n+1, n+2 for "pout";

Documentation/hwmon/mp2975.rst line 111

Quoted 10 lines

Documentation/hwmon/mp2975.rst new file +10 -0

+
+**power1_alarm**
+
+**power[2-{n+1}]_highest**
+
+**power[1-{2n+1}]_input**
+
+**power[1-{2n+1}]_label**
+
+The driver provides the next attributes for the temperature (only from page

0):

Quoted 32 lines

Documentation/hwmon/mp2975.rst new file +11 -0

+
+
+**temp1_crit**
+
+**temp1_crit_alarm**
+
+**temp1_input**
+
+**temp1_max**
+
+**temp1_max_alarm**

drivers/hwmon/pmbus/Kconfig +9 -0

index e35db489b76f..1e6157e85437 100644
@@ -200,6 +200,15 @@ config SENSORS_MAX8688
 	  This driver can also be built as a module. If so, the module will
 	  be called max8688.
 
+config SENSORS_MP2975
+	tristate "MPS MP2975"
+	help
+	  If you say yes here you get hardware monitoring support for MPS
+	  MP2975 Dual Loop Digital Multi-Phase Controller.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called mp2975.
+
 config SENSORS_PXE1610
 	tristate "Infineon PXE1610"
 	help

(quoted diff) +0 -0

Quoted 1 line

b/drivers/hwmon/pmbus/Makefile index c4b15db996ad..0e2832e73cfc

100644

drivers/hwmon/pmbus/Makefile obj-$(CONFIG_SENSORS_MAX20751) +=

Quoted 3 lines

drivers/hwmon/pmbus/Makefile +0 -0

@@ -23,6 +23,7 @@ obj-$(CONFIG_SENSORS_MAX20751)	+=

max20751.o

Quoted 59 lines

drivers/hwmon/pmbus/Makefile +1 -0

 obj-$(CONFIG_SENSORS_MAX31785)	+= max31785.o
 obj-$(CONFIG_SENSORS_MAX34440)	+= max34440.o
 obj-$(CONFIG_SENSORS_MAX8688)	+= max8688.o
+obj-$(CONFIG_SENSORS_MP2975)	+= mp2975.o
 obj-$(CONFIG_SENSORS_PXE1610)	+= pxe1610.o
 obj-$(CONFIG_SENSORS_TPS40422)	+= tps40422.o
 obj-$(CONFIG_SENSORS_TPS53679)	+= tps53679.o

(quoted diff) +0 -0

b/drivers/hwmon/pmbus/mp2975.c new file mode 100644 index 000000000000..f2f3e74c4953

drivers/hwmon/pmbus/mp2975.c new file +46 -0

@@ -0,0 +1,772 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Hardware monitoring driver for MPS Multi-phase Digital VR
+Controllers
+ *
+ * Copyright (C) 2020 Nvidia Technologies Ltd.
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include "pmbus.h"
+
+/* Vendor specific registers. */
+#define MP2975_MFR_APS_HYS_R2		0x0d
+#define MP2975_MFR_SLOPE_TRIM3		0x1d
+#define MP2975_MFR_VR_MULTI_CONFIG_R1	0x0d
+#define MP2975_MFR_VR_MULTI_CONFIG_R2	0x1d
+#define MP2975_MFR_APS_DECAY_ADV	0x56
+#define MP2975_MFR_DC_LOOP_CTRL		0x59
+#define MP2975_MFR_OCP_UCP_PHASE_SET	0x65
+#define MP2975_MFR_VR_CONFIG1		0x68
+#define MP2975_MFR_READ_CS1_2		0x82
+#define MP2975_MFR_READ_CS3_4		0x83
+#define MP2975_MFR_READ_CS5_6		0x84
+#define MP2975_MFR_READ_CS7_8		0x85
+#define MP2975_MFR_READ_CS9_10		0x86
+#define MP2975_MFR_READ_CS11_12		0x87
+#define MP2975_MFR_READ_IOUT_PK		0x90
+#define MP2975_MFR_READ_POUT_PK		0x91
+#define MP2975_MFR_READ_VREF_R1		0xa1
+#define MP2975_MFR_READ_VREF_R2		0xa3
+#define MP2975_MFR_OVP_TH_SET		0xe5
+#define MP2975_MFR_UVP_SET		0xe6
+
+#define MP2975_VOUT_FORMAT		BIT(15)
+#define MP2975_VID_STEP_SEL_R1		BIT(4)
+#define MP2975_IMVP9_EN_R1		BIT(13)
+#define MP2975_VID_STEP_SEL_R2		BIT(3)
+#define MP2975_IMVP9_EN_R2		BIT(12)
+#define MP2975_PRT_THRES_DIV_OV_EN	BIT(14)
+#define MP2975_DRMOS_KCS		GENMASK(13, 12)
+#define MP2975_PROT_DEV_OV_OFF		10
+#define MP2975_PROT_DEV_OV_ON		5

drivers/hwmon/pmbus/mp2975.c line 56

Quoted 10 lines

drivers/hwmon/pmbus/mp2975.c new file +10 -0

+#define MP2975_SENSE_AMPL		BIT(11)
+#define MP2975_SENSE_AMPL_UNIT		1
+#define MP2975_SENSE_AMPL_HALF		2
+#define MP2975_VIN_UV_LIMIT_UNIT	8
+
+#define MP2975_MAX_PHASE_RAIL1	8
+#define MP2975_MAX_PHASE_RAIL2	4
+#define MP2975_PAGE_NUM		2
+
+#define MP2975_RAIL2_FUNC	(PMBUS_HAVE_VOUT |

PMBUS_HAVE_STATUS_VOUT | \

drivers/hwmon/pmbus/mp2975.c line 57

Quoted 1 line

drivers/hwmon/pmbus/mp2975.c new file +1 -0

+				 PMBUS_HAVE_IOUT |

PMBUS_HAVE_STATUS_IOUT | \

Quoted 23 lines

drivers/hwmon/pmbus/mp2975.c new file +23 -0

+				 PMBUS_PHASE_VIRTUAL)
+
+struct mp2975_data {
+	struct pmbus_driver_info info;
+	int vout_scale;
+	int vid_step[MP2975_PAGE_NUM];
+	int vref[MP2975_PAGE_NUM];
+	int vref_off[MP2975_PAGE_NUM];
+	int vout_max[MP2975_PAGE_NUM];
+	int vout_ov_fixed[MP2975_PAGE_NUM];
+	int vout_format[MP2975_PAGE_NUM];
+	int curr_sense_gain[MP2975_PAGE_NUM]; };
+
+#define to_mp2975_data(x)  container_of(x, struct mp2975_data, info)
+
+static int mp2975_read_byte_data(struct i2c_client *client, int page,
+int reg) {
+	switch (reg) {
+	case PMBUS_VOUT_MODE:
+		/*
+		 * Enforce VOUT direct format, since device allows to set the
+		 * different formats for the different rails. Conversion from
+		 * VID to direct provided by driver internally, in case it is

drivers/hwmon/pmbus/mp2975.c

Quoted 10 lines

drivers/hwmon/pmbus/mp2975.c new file +10 -0

+		 * necessary.
+		 */
+		return PB_VOUT_MODE_DIRECT;
+	default:
+		return -ENODATA;
+	}
+}
+
+static int
+mp2975_read_word_helper(struct i2c_client *client, int page, int phase, u8

reg,

Quoted 37 lines

drivers/hwmon/pmbus/mp2975.c new file +37 -0

+			u16 mask)
+{
+	int ret = pmbus_read_word_data(client, page, phase, reg);
+
+	return (ret > 0) ? ret & mask : ret; }
+
+static int
+mp2975_vid2direct(int vrf, int val)
+{
+	switch (vrf) {
+	case vr12:
+		if (val >= 0x01)
+			return 250 + (val - 1) * 5;
+		break;
+	case vr13:
+		if (val >= 0x01)
+			return 500 + (val - 1) * 10;
+		break;
+	case imvp9:
+		if (val >= 0x01)
+			return 200 + (val - 1) * 10;
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int
+mp2975_read_phase(struct i2c_client *client, struct mp2975_data *data,
+		  int page, int phase, u8 reg)
+{
+	int ph_curr, ret;
+
+	ret = pmbus_read_word_data(client, page, phase, reg);
+	if (ret < 0)
+		return ret;

drivers/hwmon/pmbus/mp2975.c

Quoted 10 lines

drivers/hwmon/pmbus/mp2975.c new file +10 -0

+
+	if (!((phase + 1) % MP2975_PAGE_NUM))
+		ret >>= 8;
+	ret &= 0xff;
+
+	/*
+	 * Output value is calculated as: (READ_CSx / 80 – 1.23) / (Kcs * Rcs)
+	 * where:
+	 * - Kcs is the DrMOS current sense gain of power stage, which is
+	 *   obtained from the register MP2975_MFR_VR_CONFIG1, bits 13-12

with

drivers/hwmon/pmbus/mp2975.c

Quoted 12 lines

drivers/hwmon/pmbus/mp2975.c new file +12 -0

+	 *   the following selection of DrMOS (data->curr_sense_gain[page]):
+	 *   00b - 5µA/A, 01b - 8.5µA/A, 10b - 9.7µA/A, 11b - 10µA/A.
+	 * - Rcs is the internal phase current sense resistor which is constant
+	 *   value 1kΩ.
+	 */
+	ph_curr = ret * 100 - 9800;
+
+	/*
+	 * Current phase sensing, providing by the device is not accurate
+	 * for the light load. This because sampling of current occurrence of
+	 * bit weight has a big deviation for light load. For handling such
+	 * case phase current is represented as the maximum between the

value

drivers/hwmon/pmbus/mp2975.c

Quoted 3 lines

drivers/hwmon/pmbus/mp2975.c new file +3 -0

+	 * calculated  above and total rail current divided by number phases.
+	 */
+	ret = pmbus_read_word_data(client, page, phase,

PMBUS_READ_IOUT);

Quoted 12 lines

drivers/hwmon/pmbus/mp2975.c new file +5 -0

+	if (ret < 0)
+		return ret;
+
+	return max_t(int, DIV_ROUND_CLOSEST(ret, data->info.phases[page]),
+		     DIV_ROUND_CLOSEST(ph_curr, data-

curr_sense_gain[page])); }

drivers/hwmon/pmbus/mp2975.c new file +6 -0

+
+static int
+mp2975_read_phases(struct i2c_client *client, struct mp2975_data *data,
+		   int page, int phase)
+{
+	int ret;

drivers/hwmon/pmbus/mp2975.c line 216

Quoted 10 lines

drivers/hwmon/pmbus/mp2975.c new file +10 -0

+
+	if (page) {
+		switch (phase) {
+		case 0 ... 1:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS7_8);
+			break;
+		case 2 ... 3:
+			ret = mp2975_read_phase(client, data, page, phase,
+

	MP2975_MFR_READ_CS9_10);

drivers/hwmon/pmbus/mp2975.c line 216

Quoted 4 lines

drivers/hwmon/pmbus/mp2975.c new file +4 -0

+			break;
+		case 4 ... 5:
+			ret = mp2975_read_phase(client, data, page, phase,
+

	MP2975_MFR_READ_CS11_12);

Quoted 15 lines

drivers/hwmon/pmbus/mp2975.c new file +15 -0

+			break;
+		default:
+			return -ENODATA;
+		}
+	} else {
+		switch (phase) {
+		case 0 ... 1:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS1_2);
+			break;
+		case 2 ... 3:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS3_4);
+			break;
+		case 4 ... 5:

drivers/hwmon/pmbus/mp2975.c line 216

Quoted 10 lines

drivers/hwmon/pmbus/mp2975.c new file +10 -0

+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS5_6);
+			break;
+		case 6 ... 7:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS7_8);
+			break;
+		case 8 ... 9:
+			ret = mp2975_read_phase(client, data, page, phase,
+

	MP2975_MFR_READ_CS9_10);

drivers/hwmon/pmbus/mp2975.c line 216

Quoted 4 lines

drivers/hwmon/pmbus/mp2975.c new file +4 -0

+			break;
+		case 10 ... 11:
+			ret = mp2975_read_phase(client, data, page, phase,
+

	MP2975_MFR_READ_CS11_12);

Quoted 17 lines

drivers/hwmon/pmbus/mp2975.c new file +17 -0

+			break;
+		default:
+			return -ENODATA;
+		}
+	}
+	return ret;
+}
+
+static int mp2975_read_word_data(struct i2c_client *client, int page,
+				 int phase, int reg)
+{
+	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+	struct mp2975_data *data = to_mp2975_data(info);
+	int ret;
+
+	switch (reg) {
+	case PMBUS_OT_FAULT_LIMIT:

drivers/hwmon/pmbus/mp2975.c

Quoted 10 lines

drivers/hwmon/pmbus/mp2975.c new file +10 -0

+		ret = mp2975_read_word_helper(client, page, phase, reg,
+					      GENMASK(7, 0));
+		break;
+	case PMBUS_VIN_OV_FAULT_LIMIT:
+		ret = mp2975_read_word_helper(client, page, phase, reg,
+					      GENMASK(7, 0));
+		if (ret < 0)
+			return ret;
+
+		ret = DIV_ROUND_CLOSEST(ret,

MP2975_VIN_UV_LIMIT_UNIT);

Quoted 27 lines

drivers/hwmon/pmbus/mp2975.c new file +27 -0

+		break;
+	case PMBUS_VOUT_OV_FAULT_LIMIT:
+		/*
+		 * Register provides two values for over-voltage protection
+		 * threshold for fixed (ovp2) and tracking (ovp1) modes. The
+		 * minimum of these two values is provided as over-voltage
+		 * fault alarm.
+		 */
+		ret = mp2975_read_word_helper(client, page, phase,
+					      MP2975_MFR_OVP_TH_SET,
+					      GENMASK(2, 0));
+		if (ret < 0)
+			return ret;
+
+		ret = min_t(int, data->vout_max[page] + 50 * (ret + 1),
+			    data->vout_ov_fixed[page]);
+		break;
+	case PMBUS_VOUT_UV_FAULT_LIMIT:
+		ret = mp2975_read_word_helper(client, page, phase,
+					      MP2975_MFR_UVP_SET,
+					      GENMASK(2, 0));
+		if (ret < 0)
+			return ret;
+
+		ret = DIV_ROUND_CLOSEST(data->vref[page] * 10 - 50 *
+					(ret + 1) * data->vout_scale, 10);
+		break;

drivers/hwmon/pmbus/mp2975.c

Quoted 10 lines

drivers/hwmon/pmbus/mp2975.c new file +10 -0

+	case PMBUS_READ_VOUT:
+		ret = mp2975_read_word_helper(client, page, phase, reg,
+					      GENMASK(11, 0));
+		if (ret < 0)
+			return ret;
+
+		/*
+		 * READ_VOUT can be provided in VID or direct format. The
+		 * format type is specified by bit 15 of the register
+		 * MP2975_MFR_DC_LOOP_CTRL. The driver enforces VOUT

direct

drivers/hwmon/pmbus/mp2975.c

Quoted 7 lines

drivers/hwmon/pmbus/mp2975.c new file +7 -0

+		 * format, since device allows to set the different formats for
+		 * the different rails and also all VOUT limits registers are
+		 * provided in a direct format. In case format is VID - convert
+		 * to direct.
+		 */
+		if (data->vout_format[page] == vid)
+			ret = mp2975_vid2direct(info->vrm_version[page],

ret);

Quoted 53 lines

drivers/hwmon/pmbus/mp2975.c new file +53 -0

+		break;
+	case PMBUS_VIRT_READ_POUT_MAX:
+		ret = mp2975_read_word_helper(client, page, phase,
+					      MP2975_MFR_READ_POUT_PK,
+					      GENMASK(12, 0));
+		if (ret < 0)
+			return ret;
+
+		ret = DIV_ROUND_CLOSEST(ret, 4);
+		break;
+	case PMBUS_VIRT_READ_IOUT_MAX:
+		ret = mp2975_read_word_helper(client, page, phase,
+					      MP2975_MFR_READ_IOUT_PK,
+					      GENMASK(12, 0));
+		if (ret < 0)
+			return ret;
+
+		ret = DIV_ROUND_CLOSEST(ret, 4);
+		break;
+	case PMBUS_READ_IOUT:
+		ret = mp2975_read_phases(client, data, page, phase);
+		if (ret < 0)
+			return ret;
+
+		break;
+	case PMBUS_UT_WARN_LIMIT:
+	case PMBUS_UT_FAULT_LIMIT:
+	case PMBUS_VIN_UV_WARN_LIMIT:
+	case PMBUS_VIN_UV_FAULT_LIMIT:
+	case PMBUS_VOUT_UV_WARN_LIMIT:
+	case PMBUS_VOUT_OV_WARN_LIMIT:
+	case PMBUS_VIN_OV_WARN_LIMIT:
+	case PMBUS_IIN_OC_FAULT_LIMIT:
+	case PMBUS_IOUT_OC_LV_FAULT_LIMIT:
+	case PMBUS_IIN_OC_WARN_LIMIT:
+	case PMBUS_IOUT_OC_WARN_LIMIT:
+	case PMBUS_IOUT_OC_FAULT_LIMIT:
+	case PMBUS_IOUT_UC_FAULT_LIMIT:
+	case PMBUS_POUT_OP_FAULT_LIMIT:
+	case PMBUS_POUT_OP_WARN_LIMIT:
+	case PMBUS_PIN_OP_WARN_LIMIT:
+		return -ENXIO;
+	default:
+		return -ENODATA;
+	}
+
+	return ret;
+}
+
+static int mp2975_identify_multiphase_rail2(struct i2c_client
+*client) {
+	int ret;
+

drivers/hwmon/pmbus/mp2975.c

Quoted 10 lines

drivers/hwmon/pmbus/mp2975.c new file +10 -0

+	/*
+	 * Identify multiphase for rail 2 - could be from 0 to 4.
+	 * In case phase number is zero – only page zero is supported
+	 */
+	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
+	if (ret < 0)
+		return ret;
+
+	/* Identify multiphase for rail 2 - could be from 0 to 4. */
+	ret = i2c_smbus_read_word_data(client,

MP2975_MFR_VR_MULTI_CONFIG_R2);

Quoted 12 lines

drivers/hwmon/pmbus/mp2975.c new file +12 -0

+	if (ret < 0)
+		return ret;
+
+	ret &= GENMASK(2, 0);
+	return (ret >= 4) ? 4 : ret;
+}
+
+static void mp2975_set_phase_rail1(struct pmbus_driver_info *info) {
+	int i;
+
+	for (i = 0 ; i < info->phases[0]; i++)
+		info->pfunc[i] = PMBUS_HAVE_IOUT;

drivers/hwmon/pmbus/mp2975.c

Quoted 10 lines

drivers/hwmon/pmbus/mp2975.c new file +10 -0

+}
+
+static void
+mp2975_set_phase_rail2(struct pmbus_driver_info *info, int
+num_phases) {
+	int i;
+
+	/* Set phases for rail 2 from upper to lower. */
+	for (i = 1; i <= num_phases; i++)
+		info->pfunc[MP2975_MAX_PHASE_RAIL1 - i] =

PMBUS_HAVE_IOUT; }

drivers/hwmon/pmbus/mp2975.c

Quoted 3 lines

drivers/hwmon/pmbus/mp2975.c new file +3 -0

+
+static int
+mp2975_identify_multiphase(struct i2c_client *client, struct mp2975_data

*data,

drivers/hwmon/pmbus/mp2975.c

Quoted 9 lines

drivers/hwmon/pmbus/mp2975.c new file +9 -0

+			   struct pmbus_driver_info *info) {
+	int num_phases2, ret;
+
+	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
+	if (ret < 0)
+		return ret;
+
+	/* Identify multiphase for rail 1 - could be from 1 to 8. */
+	ret = i2c_smbus_read_word_data(client,

MP2975_MFR_VR_MULTI_CONFIG_R1);

Quoted 43 lines

drivers/hwmon/pmbus/mp2975.c new file +43 -0

+	if (ret <= 0)
+		return ret;
+
+	info->phases[0] = ret & GENMASK(3, 0);
+
+	/*
+	 * The device provides a total of 8 PWM pins, and can be configured
+	 * to different phase count applications for rail 1 and rail 2.
+	 * Rail 1 can be set to 8 phases, while rail 2 can only be set to 4
+	 * phases at most. When rail 1’s phase count is configured as 0, rail
+	 * 1 operates with 1-phase DCM. When rail 2 phase count is configured
+	 * as 0, rail 2 is disabled.
+	 */
+	if (info->phases[0] > MP2975_MAX_PHASE_RAIL1)
+		return -EINVAL;
+
+	mp2975_set_phase_rail1(info);
+	num_phases2 = min(MP2975_MAX_PHASE_RAIL1 - info->phases[0],
+			  MP2975_MAX_PHASE_RAIL2);
+	if (info->phases[1] && info->phases[1] <= num_phases2)
+		mp2975_set_phase_rail2(info, num_phases2);
+
+	return 0;
+}
+
+static int
+mp2975_identify_vid(struct i2c_client *client, struct mp2975_data *data,
+		    struct pmbus_driver_info *info, u32 reg, int page,
+		    u32 imvp_bit, u32 vr_bit)
+{
+	int ret;
+
+	/* Identify VID mode and step selection. */
+	ret = i2c_smbus_read_word_data(client, reg);
+	if (ret < 0)
+		return ret;
+
+	if (ret & imvp_bit) {
+		info->vrm_version[page] = imvp9;
+		data->vid_step[page] = MP2975_PROT_DEV_OV_OFF;
+	} else if (ret & vr_bit) {
+		info->vrm_version[page] = vr12;
+		data->vid_step[page] = MP2975_PROT_DEV_OV_ON;

drivers/hwmon/pmbus/mp2975.c

Quoted 10 lines

drivers/hwmon/pmbus/mp2975.c new file +10 -0

+	} else {
+		info->vrm_version[page] = vr13;
+		data->vid_step[page] = MP2975_PROT_DEV_OV_OFF;
+	}
+
+	return 0;
+}
+
+static int
+mp2975_identify_rails_vid(struct i2c_client *client, struct mp2975_data

*data,

drivers/hwmon/pmbus/mp2975.c

Quoted 12 lines

drivers/hwmon/pmbus/mp2975.c new file +12 -0

+			  struct pmbus_driver_info *info)
+{
+	int ret;
+
+	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
+	if (ret < 0)
+		return ret;
+
+	/* Identify VID mode for rail 1. */
+	ret = mp2975_identify_vid(client, data, info,
+				  MP2975_MFR_VR_MULTI_CONFIG_R1, 0,
+				  MP2975_IMVP9_EN_R1,

MP2975_VID_STEP_SEL_R1);

drivers/hwmon/pmbus/mp2975.c line 456

Quoted 7 lines

drivers/hwmon/pmbus/mp2975.c new file +7 -0

+	if (ret < 0)
+		return ret;
+
+	/* Identify VID mode for rail 2, if connected. */
+	if (info->phases[1])
+		ret = mp2975_identify_vid(client, data, info,
+

MP2975_MFR_VR_MULTI_CONFIG_R2, 1,

Quoted 4 lines

drivers/hwmon/pmbus/mp2975.c new file +4 -0

+					  MP2975_IMVP9_EN_R2,
+					  MP2975_VID_STEP_SEL_R2);
+	return ret;
+}

drivers/hwmon/pmbus/mp2975.c

Quoted 10 lines

drivers/hwmon/pmbus/mp2975.c new file +10 -0

+
+static int
+mp2975_current_sense_gain_get(struct i2c_client *client,
+			      struct mp2975_data *data)
+{
+	int i, ret;
+
+	/*
+	 * Obtain DrMOS current sense gain of power stage from the register
+	 * MP2975_MFR_VR_CONFIG1, bits 13-12. The value is selected as

below:

Quoted 33 lines

drivers/hwmon/pmbus/mp2975.c new file +33 -0

+	 * 00b - 5µA/A, 01b - 8.5µA/A, 10b - 9.7µA/A, 11b - 10µA/A. Other
+	 * values are invalid.
+	 */
+	for (i = 0 ; i < data->info.pages; i++) {
+		ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, i);
+		if (ret < 0)
+			return ret;
+		ret = i2c_smbus_read_word_data(client,
+					       MP2975_MFR_VR_CONFIG1);
+		if (ret < 0)
+			return ret;
+
+		switch ((ret & MP2975_DRMOS_KCS) >> 12) {
+		case 0:
+			data->curr_sense_gain[i] = 50;
+			break;
+		case 1:
+			data->curr_sense_gain[i] = 85;
+			break;
+		case 2:
+			data->curr_sense_gain[i] = 97;
+			break;
+		default:
+			data->curr_sense_gain[i] = 100;
+			break;
+		}
+	}
+
+	return 0;
+}
+
+static int
+mp2975_vref_get(struct i2c_client *client, struct mp2975_data *data,

drivers/hwmon/pmbus/mp2975.c

Quoted 10 lines

drivers/hwmon/pmbus/mp2975.c new file +10 -0

+		struct pmbus_driver_info *info)
+{
+	int ret;
+
+	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 3);
+	if (ret < 0)
+		return ret;
+
+	/* Get voltage reference value for rail 1. */
+	ret = i2c_smbus_read_word_data(client,

MP2975_MFR_READ_VREF_R1);

drivers/hwmon/pmbus/mp2975.c

Quoted 8 lines

drivers/hwmon/pmbus/mp2975.c new file +8 -0

+	if (ret < 0)
+		return ret;
+
+	data->vref[0] = ret * data->vid_step[0];
+
+	/* Get voltage reference value for rail 2, if connected. */
+	if (data->info.pages == MP2975_PAGE_NUM) {
+		ret = i2c_smbus_read_word_data(client,

MP2975_MFR_READ_VREF_R2);

drivers/hwmon/pmbus/mp2975.c

Quoted 10 lines

drivers/hwmon/pmbus/mp2975.c new file +10 -0

+		if (ret < 0)
+			return ret;
+
+		data->vref[1] = ret * data->vid_step[1];
+	}
+	return 0;
+}
+
+static int
+mp2975_vref_offset_get(struct i2c_client *client, struct mp2975_data

*data,

Quoted 25 lines

drivers/hwmon/pmbus/mp2975.c new file +25 -0

+		       int page)
+{
+	int ret;
+
+	ret = i2c_smbus_read_word_data(client, MP2975_MFR_OVP_TH_SET);
+	if (ret < 0)
+		return ret;
+
+	switch ((ret & GENMASK(5, 3)) >> 3) {
+	case 1:
+		data->vref_off[page] = 140;
+		break;
+	case 2:
+		data->vref_off[page] = 220;
+		break;
+	case 4:
+		data->vref_off[page] = 400;
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int

drivers/hwmon/pmbus/mp2975.c

Quoted 10 lines

drivers/hwmon/pmbus/mp2975.c new file +10 -0

+mp2975_vout_max_get(struct i2c_client *client, struct mp2975_data *data,
+		    struct pmbus_driver_info *info, int page) {
+	int ret;
+
+	/* Get maximum reference voltage of VID-DAC in VID format. */
+	ret = i2c_smbus_read_word_data(client, PMBUS_VOUT_MAX);
+	if (ret < 0)
+		return ret;
+
+	data->vout_max[page] = mp2975_vid2direct(info->vrm_version[page],

ret &

drivers/hwmon/pmbus/mp2975.c

Quoted 10 lines

drivers/hwmon/pmbus/mp2975.c new file +10 -0

+						 GENMASK(8, 0));
+	return 0;
+}
+
+static int
+mp2975_identify_vout_format(struct i2c_client *client,
+			    struct mp2975_data *data, int page) {
+	int ret;
+
+	ret = i2c_smbus_read_word_data(client,

MP2975_MFR_DC_LOOP_CTRL);

drivers/hwmon/pmbus/mp2975.c

Quoted 12 lines

drivers/hwmon/pmbus/mp2975.c new file +12 -0

+	if (ret < 0)
+		return ret;
+
+	if (ret & MP2975_VOUT_FORMAT)
+		data->vout_format[page] = vid;
+	else
+		data->vout_format[page] = direct;
+	return 0;
+}
+
+static int
+mp2975_vout_ov_scale_get(struct i2c_client *client, struct mp2975_data

*data,

drivers/hwmon/pmbus/mp2975.c

Quoted 11 lines

drivers/hwmon/pmbus/mp2975.c new file +11 -0

+			 struct pmbus_driver_info *info)
+{
+	int thres_dev, sense_ampl, ret;
+
+	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 0);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * Get divider for over- and under-voltage protection thresholds
+	 * configuration from the Advanced Options of Auto Phase Shedding

and

drivers/hwmon/pmbus/mp2975.c

Quoted 3 lines

drivers/hwmon/pmbus/mp2975.c new file +3 -0

+	 * decay register.
+	 */
+	ret = i2c_smbus_read_word_data(client,

MP2975_MFR_APS_DECAY_ADV);

drivers/hwmon/pmbus/mp2975.c

Quoted 3 lines

drivers/hwmon/pmbus/mp2975.c new file +3 -0

+	if (ret >= 0)
+		thres_dev = ret & MP2975_PRT_THRES_DIV_OV_EN ?
+			    MP2975_PROT_DEV_OV_ON :

MP2975_PROT_DEV_OV_OFF;

drivers/hwmon/pmbus/mp2975.c

Quoted 2 lines

drivers/hwmon/pmbus/mp2975.c new file +2 -0

+	else
+		return ret;

Why not the usual

	if (ret < 0)
		return ret;
	thres_dev = ret & MP2975_PRT_THRES_DIV_OV_EN ?
		    MP2975_PROT_DEV_OV_ON :

MP2975_PROT_DEV_OV_OFF;

drivers/hwmon/pmbus/mp2975.c

Quoted 5 lines

drivers/hwmon/pmbus/mp2975.c new file +5 -0

+
+	/* Select the gain of remote sense amplifier. */
+	ret = i2c_smbus_read_word_data(client, PMBUS_VOUT_SCALE_LOOP);
+	if (ret >= 0)
+		sense_ampl = ret & MP2975_SENSE_AMPL ?

MP2975_SENSE_AMPL_HALF :

drivers/hwmon/pmbus/mp2975.c line 612

Quoted 3 lines

drivers/hwmon/pmbus/mp2975.c new file +3 -0

+			     MP2975_SENSE_AMPL_UNIT;
+	else
+		return ret;

Same here. The reversed logic just makes the code difficult to read.

If you want, I can make that change and apply the patch. Let me know.

Guenter

Quoted 56 lines

drivers/hwmon/pmbus/mp2975.c new file +44 -0

+
+	data->vout_scale = sense_ampl * thres_dev;
+
+	return 0;
+}
+
+static int
+mp2975_vout_per_rail_config_get(struct i2c_client *client,
+				struct mp2975_data *data,
+				struct pmbus_driver_info *info)
+{
+	int i, ret;
+
+	for (i = 0; i < data->info.pages; i++) {
+		ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, i);
+		if (ret < 0)
+			return ret;
+
+		/* Obtain voltage reference offsets. */
+		ret = mp2975_vref_offset_get(client, data, i);
+		if (ret < 0)
+			return ret;
+
+		/* Obtain maximum voltage values. */
+		ret = mp2975_vout_max_get(client, data, info, i);
+		if (ret < 0)
+			return ret;
+
+		/*
+		 * Get VOUT format for READ_VOUT command : VID or direct.
+		 * Pages on same device can be configured with different
+		 * formats.
+		 */
+		ret = mp2975_identify_vout_format(client, data, i);
+		if (ret < 0)
+			return ret;
+
+		/*
+		 * Set over-voltage fixed value. Thresholds are provided as
+		 * fixed value, and tracking value. The minimum of them are
+		 * exposed as over-voltage critical threshold.
+		 */
+		data->vout_ov_fixed[i] = data->vref[i] +
+					 DIV_ROUND_CLOSEST(data-

vref_off[i] *

drivers/hwmon/pmbus/mp2975.c new file +11 -0

+							   data->vout_scale,
+							   10);
+	}
+
+	return 0;
+}
+
+static struct pmbus_driver_info mp2975_info = {
+	.pages = 1,
+	.format[PSC_VOLTAGE_IN] = linear,
+	.format[PSC_VOLTAGE_OUT] = direct,

drivers/hwmon/pmbus/mp2975.c

Quoted 10 lines

drivers/hwmon/pmbus/mp2975.c new file +10 -0

+	.format[PSC_TEMPERATURE] = direct,
+	.format[PSC_CURRENT_IN] = linear,
+	.format[PSC_CURRENT_OUT] = direct,
+	.format[PSC_POWER] = direct,
+	.m[PSC_TEMPERATURE] = 1,
+	.m[PSC_VOLTAGE_OUT] = 1,
+	.R[PSC_VOLTAGE_OUT] = 3,
+	.m[PSC_CURRENT_OUT] = 1,
+	.m[PSC_POWER] = 1,
+	.func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT |

PMBUS_HAVE_STATUS_VOUT |

drivers/hwmon/pmbus/mp2975.c

Quoted 1 line

drivers/hwmon/pmbus/mp2975.c new file +1 -0

+		PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT |

PMBUS_HAVE_STATUS_IOUT |

drivers/hwmon/pmbus/mp2975.c

Quoted 1 line

drivers/hwmon/pmbus/mp2975.c new file +1 -0

+		PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP |

PMBUS_HAVE_POUT |

drivers/hwmon/pmbus/mp2975.c

Quoted 1 line

drivers/hwmon/pmbus/mp2975.c new file +1 -0

+		PMBUS_HAVE_PIN | PMBUS_HAVE_STATUS_INPUT |

PMBUS_PHASE_VIRTUAL,

Quoted 90 lines

drivers/hwmon/pmbus/mp2975.c new file +90 -0

+	.read_byte_data = mp2975_read_byte_data,
+	.read_word_data = mp2975_read_word_data, };
+
+static int mp2975_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	struct pmbus_driver_info *info;
+	struct mp2975_data *data;
+	int ret;
+
+	data = devm_kzalloc(&client->dev, sizeof(struct mp2975_data),
+			    GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	memcpy(&data->info, &mp2975_info, sizeof(*info));
+	info = &data->info;
+
+	/* Identify multiphase configuration for rail 2. */
+	ret = mp2975_identify_multiphase_rail2(client);
+	if (ret < 0)
+		return ret;
+
+	if (ret) {
+		/* Two rails are connected. */
+		data->info.pages = MP2975_PAGE_NUM;
+		data->info.phases[1] = ret;
+		data->info.func[1] = MP2975_RAIL2_FUNC;
+	}
+
+	/* Identify multiphase configuration. */
+	ret = mp2975_identify_multiphase(client, data, info);
+	if (ret)
+		return ret;
+
+	/* Identify VID setting per rail. */
+	ret = mp2975_identify_rails_vid(client, data, info);
+	if (ret < 0)
+		return ret;
+
+	/* Obtain current sense gain of power stage. */
+	ret = mp2975_current_sense_gain_get(client, data);
+	if (ret)
+		return ret;
+
+	/* Obtain voltage reference values. */
+	ret = mp2975_vref_get(client, data, info);
+	if (ret)
+		return ret;
+
+	/* Obtain vout over-voltage scales. */
+	ret = mp2975_vout_ov_scale_get(client, data, info);
+	if (ret < 0)
+		return ret;
+
+	/* Obtain offsets, maximum and format for vout. */
+	ret = mp2975_vout_per_rail_config_get(client, data, info);
+	if (ret)
+		return ret;
+
+	return pmbus_do_probe(client, id, info); }
+
+static const struct i2c_device_id mp2975_id[] = {
+	{"mp2975", 0},
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, mp2975_id);
+
+static const struct of_device_id __maybe_unused mp2975_of_match[] = {
+	{.compatible = "mps,mp2975"},
+	{}
+};
+MODULE_DEVICE_TABLE(of, mp2975_of_match);
+
+static struct i2c_driver mp2975_driver = {
+	.driver = {
+		.name = "mp2975",
+		.of_match_table = of_match_ptr(mp2975_of_match),
+	},
+	.probe = mp2975_probe,
+	.remove = pmbus_do_remove,
+	.id_table = mp2975_id,
+};
+
+module_i2c_driver(mp2975_driver);
+
+MODULE_AUTHOR("Vadim Pasternak <[email protected]>");
+MODULE_DESCRIPTION("PMBus driver for MPS MP2975 device");
+MODULE_LICENSE("GPL");

Add support for mp295 device from Monolithic Power Systems, Inc. (MPS) vendor. This is a dual-loop, digital, multi-phase controller. This device:
- Supports two power rail.
- Provides 8 pulse-width modulations (PWMs), and can be configured up to 8-phase operation for rail 1 and up to 4-phase operation for rail 2.
- Supports two pages 0 and 1 for telemetry and also pages 2 and 3 for configuration.
- Can configured VOUT readout in direct or VID format and allows setting of different formats on rails 1 and 2. For VID the following protocols are available: VR13 mode with 5-mV DAC; VR13 mode with 10-mV DAC, IMVP9 mode with 5-mV DAC.

Signed-off-by Vadim Pasternak <[email protected]>

---
v3->v4
Comments pointed out by Guenter:
- Drop redundant 'return' from mp2975_identify_multiphase_rail2().
- Fix phases assignment in mp2975_set_phase_rail2().
- Fix range for the number of phases in mp2975_set_multiphase_rail2().
- Drop mp2975_set_multiphase_rail2, call instead directly mp2975_set_phase_rail2(), since the phases range is already validated for rail 2.
- Fix handling for the case of zero number of phases for rail 1 in mp2975_identify_multiphase(), which is valid case.
- Simplify logic for rail1 and rail2 setting handling in mp2975_identify_multiphase().
- Line length limit is now 100, but 'checkpatch' scripts is still consider it as error.
- Modify 'switch' statement in mp2975_current_sense_gain_get().
- Fix misspelled comment in mp2975_probe().
v1->v2
Comments pointed out by Guenter:
- Add doc fail to the patch#1 (it was sent as separate patch).
- Use standard define for VOUT mode format.
- Simplify logic in mp2975_read_phase().
- Simplify calculation of phase current in mp2975_read_phase().
- Modify return code handling in mp2975_read_word_data().
- Add missed error handling in mp2975_read_word_data().
- Drop 'fallthrough;' in mp2975_read_word_data().
- Handle error code in mp2975_identify_multiphase_rail2().
- Handle error code in mp2975_identify_multiphase().
- Drop 'goto' in mp2975_vout_per_rail_config_get() and mp2975_probe().

---
 Documentation/hwmon/mp2975.rst | 116 +++++++
 drivers/hwmon/pmbus/Kconfig    |   9 +
 drivers/hwmon/pmbus/Makefile   |   1 +
 drivers/hwmon/pmbus/mp2975.c   | 772 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 898 insertions(+)
 create mode 100644 Documentation/hwmon/mp2975.rst
 create mode 100644 drivers/hwmon/pmbus/mp2975.c

Documentation/hwmon/mp2975.rst new file +116 -0

new file mode 100644
index 000000000000..5b0609c62f48
@@ -0,0 +1,116 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver mp2975
+====================
+
+Supported chips:
+
+  * MPS MP12254
+
+    Prefix: 'mp2975'
+
+Author:
+
+	Vadim Pasternak <[email protected]>
+
+Description
+-----------
+
+This driver implements support for Monolithic Power Systems, Inc. (MPS)
+vendor dual-loop, digital, multi-phase controller MP2975.
+
+This device:
+- Supports up to two power rail.
+- Provides 8 pulse-width modulations (PWMs), and can be configured up
+  to 8-phase operation for rail 1 and up to 4-phase operation for rail
+  2.
+- Supports two pages 0 and 1 for telemetry and also pages 2 and 3 for
+  configuration.
+- Can configured VOUT readout in direct or VID format and allows
+  setting of different formats on rails 1 and 2. For VID the following
+  protocols are available: VR13 mode with 5-mV DAC; VR13 mode with
+  10-mV DAC, IMVP9 mode with 5-mV DAC.
+
+Device supports:
+- SVID interface.
+- AVSBus interface.
+
+Device complaint with:
+- PMBus rev 1.3 interface.
+
+Device supports direct format for reading output current, output voltage,
+input and output power and temperature.
+Device supports linear format for reading input voltage and input power.
+Device supports VID and direct formats for reading output voltage.
+The below VID modes are supported: VR12, VR13, IMVP9.
+
+The driver provides the next attributes for the current:
+- for current in: input, maximum alarm;
+- for current out input, maximum alarm and highest values;
+- for phase current: input and label.
+attributes.
+The driver exports the following attributes via the 'sysfs' files, where
+- 'n' is number of telemetry pages (from 1 to 2);
+- 'k' is number of configured phases (from 1 to 8);
+- indexes 1, 1*n for "iin";
+- indexes n+1, n+2 for "iout";
+- indexes 2*n+1 ... 2*n + k for phases.
+
+**curr[1-{2n}]_alarm**
+
+**curr[{n+1}-{n+2}]_highest**
+
+**curr[1-{2n+k}]_input**
+
+**curr[1-{2n+k}]_label**
+
+The driver provides the next attributes for the voltage:
+- for voltage in: input, high critical threshold, high critical alarm, all only
+  from page 0;
+- for voltage out: input, low and high critical thresholds, low and high
+  critical alarms, from pages 0 and 1;
+The driver exports the following attributes via the 'sysfs' files, where
+- 'n' is number of telemetry pages (from 1 to 2);
+- indexes 1 for "iin";
+- indexes n+1, n+2 for "vout";
+
+**in[1-{2n+1}]_crit**
+
+**in[1-{2n+1}]_crit_alarm**
+
+**in[1-{2n+1}]_input**
+
+**in[1-{2n+1}]_label**
+
+**in[2-{n+1}]_lcrit**
+
+**in[2-{n+1}1_lcrit_alarm**
+
+The driver provides the next attributes for the power:
+- for power in alarm and input.
+- for power out: highest and input.
+The driver exports the following attributes via the 'sysfs' files, where
+- 'n' is number of telemetry pages (from 1 to 2);
+- indexes 1 for "pin";
+- indexes n+1, n+2 for "pout";
+
+**power1_alarm**
+
+**power[2-{n+1}]_highest**
+
+**power[1-{2n+1}]_input**
+
+**power[1-{2n+1}]_label**
+
+The driver provides the next attributes for the temperature (only from page 0):
+
+
+**temp1_crit**
+
+**temp1_crit_alarm**
+
+**temp1_input**
+
+**temp1_max**
+
+**temp1_max_alarm**

drivers/hwmon/pmbus/Kconfig +9 -0

index e35db489b76f..1e6157e85437 100644
@@ -200,6 +200,15 @@ config SENSORS_MAX8688
 	  This driver can also be built as a module. If so, the module will
 	  be called max8688.
 
+config SENSORS_MP2975
+	tristate "MPS MP2975"
+	help
+	  If you say yes here you get hardware monitoring support for MPS
+	  MP2975 Dual Loop Digital Multi-Phase Controller.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called mp2975.
+
 config SENSORS_PXE1610
 	tristate "Infineon PXE1610"
 	help

drivers/hwmon/pmbus/Makefile +1 -0

index c4b15db996ad..0e2832e73cfc 100644
@@ -23,6 +23,7 @@ obj-$(CONFIG_SENSORS_MAX20751)	+= max20751.o
 obj-$(CONFIG_SENSORS_MAX31785)	+= max31785.o
 obj-$(CONFIG_SENSORS_MAX34440)	+= max34440.o
 obj-$(CONFIG_SENSORS_MAX8688)	+= max8688.o
+obj-$(CONFIG_SENSORS_MP2975)	+= mp2975.o
 obj-$(CONFIG_SENSORS_PXE1610)	+= pxe1610.o
 obj-$(CONFIG_SENSORS_TPS40422)	+= tps40422.o
 obj-$(CONFIG_SENSORS_TPS53679)	+= tps53679.o

drivers/hwmon/pmbus/mp2975.c new file +772 -0

new file mode 100644
index 000000000000..f2f3e74c4953
@@ -0,0 +1,772 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Hardware monitoring driver for MPS Multi-phase Digital VR Controllers
+ *
+ * Copyright (C) 2020 Nvidia Technologies Ltd.
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include "pmbus.h"
+
+/* Vendor specific registers. */
+#define MP2975_MFR_APS_HYS_R2		0x0d
+#define MP2975_MFR_SLOPE_TRIM3		0x1d
+#define MP2975_MFR_VR_MULTI_CONFIG_R1	0x0d
+#define MP2975_MFR_VR_MULTI_CONFIG_R2	0x1d
+#define MP2975_MFR_APS_DECAY_ADV	0x56
+#define MP2975_MFR_DC_LOOP_CTRL		0x59
+#define MP2975_MFR_OCP_UCP_PHASE_SET	0x65
+#define MP2975_MFR_VR_CONFIG1		0x68
+#define MP2975_MFR_READ_CS1_2		0x82
+#define MP2975_MFR_READ_CS3_4		0x83
+#define MP2975_MFR_READ_CS5_6		0x84
+#define MP2975_MFR_READ_CS7_8		0x85
+#define MP2975_MFR_READ_CS9_10		0x86
+#define MP2975_MFR_READ_CS11_12		0x87
+#define MP2975_MFR_READ_IOUT_PK		0x90
+#define MP2975_MFR_READ_POUT_PK		0x91
+#define MP2975_MFR_READ_VREF_R1		0xa1
+#define MP2975_MFR_READ_VREF_R2		0xa3
+#define MP2975_MFR_OVP_TH_SET		0xe5
+#define MP2975_MFR_UVP_SET		0xe6
+
+#define MP2975_VOUT_FORMAT		BIT(15)
+#define MP2975_VID_STEP_SEL_R1		BIT(4)
+#define MP2975_IMVP9_EN_R1		BIT(13)
+#define MP2975_VID_STEP_SEL_R2		BIT(3)
+#define MP2975_IMVP9_EN_R2		BIT(12)
+#define MP2975_PRT_THRES_DIV_OV_EN	BIT(14)
+#define MP2975_DRMOS_KCS		GENMASK(13, 12)
+#define MP2975_PROT_DEV_OV_OFF		10
+#define MP2975_PROT_DEV_OV_ON		5
+#define MP2975_SENSE_AMPL		BIT(11)
+#define MP2975_SENSE_AMPL_UNIT		1
+#define MP2975_SENSE_AMPL_HALF		2
+#define MP2975_VIN_UV_LIMIT_UNIT	8
+
+#define MP2975_MAX_PHASE_RAIL1	8
+#define MP2975_MAX_PHASE_RAIL2	4
+#define MP2975_PAGE_NUM		2
+
+#define MP2975_RAIL2_FUNC	(PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT | \
+				 PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT | \
+				 PMBUS_PHASE_VIRTUAL)
+
+struct mp2975_data {
+	struct pmbus_driver_info info;
+	int vout_scale;
+	int vid_step[MP2975_PAGE_NUM];
+	int vref[MP2975_PAGE_NUM];
+	int vref_off[MP2975_PAGE_NUM];
+	int vout_max[MP2975_PAGE_NUM];
+	int vout_ov_fixed[MP2975_PAGE_NUM];
+	int vout_format[MP2975_PAGE_NUM];
+	int curr_sense_gain[MP2975_PAGE_NUM];
+};
+
+#define to_mp2975_data(x)  container_of(x, struct mp2975_data, info)
+
+static int mp2975_read_byte_data(struct i2c_client *client, int page, int reg)
+{
+	switch (reg) {
+	case PMBUS_VOUT_MODE:
+		/*
+		 * Enforce VOUT direct format, since device allows to set the
+		 * different formats for the different rails. Conversion from
+		 * VID to direct provided by driver internally, in case it is
+		 * necessary.
+		 */
+		return PB_VOUT_MODE_DIRECT;
+	default:
+		return -ENODATA;
+	}
+}
+
+static int
+mp2975_read_word_helper(struct i2c_client *client, int page, int phase, u8 reg,
+			u16 mask)
+{
+	int ret = pmbus_read_word_data(client, page, phase, reg);
+
+	return (ret > 0) ? ret & mask : ret;
+}
+
+static int
+mp2975_vid2direct(int vrf, int val)
+{
+	switch (vrf) {
+	case vr12:
+		if (val >= 0x01)
+			return 250 + (val - 1) * 5;
+		break;
+	case vr13:
+		if (val >= 0x01)
+			return 500 + (val - 1) * 10;
+		break;
+	case imvp9:
+		if (val >= 0x01)
+			return 200 + (val - 1) * 10;
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int
+mp2975_read_phase(struct i2c_client *client, struct mp2975_data *data,
+		  int page, int phase, u8 reg)
+{
+	int ph_curr, ret;
+
+	ret = pmbus_read_word_data(client, page, phase, reg);
+	if (ret < 0)
+		return ret;
+
+	if (!((phase + 1) % MP2975_PAGE_NUM))
+		ret >>= 8;
+	ret &= 0xff;
+
+	/*
+	 * Output value is calculated as: (READ_CSx / 80 – 1.23) / (Kcs * Rcs)
+	 * where:
+	 * - Kcs is the DrMOS current sense gain of power stage, which is
+	 *   obtained from the register MP2975_MFR_VR_CONFIG1, bits 13-12 with
+	 *   the following selection of DrMOS (data->curr_sense_gain[page]):
+	 *   00b - 5µA/A, 01b - 8.5µA/A, 10b - 9.7µA/A, 11b - 10µA/A.
+	 * - Rcs is the internal phase current sense resistor which is constant
+	 *   value 1kΩ.
+	 */
+	ph_curr = ret * 100 - 9800;
+
+	/*
+	 * Current phase sensing, providing by the device is not accurate
+	 * for the light load. This because sampling of current occurrence of
+	 * bit weight has a big deviation for light load. For handling such
+	 * case phase current is represented as the maximum between the value
+	 * calculated  above and total rail current divided by number phases.
+	 */
+	ret = pmbus_read_word_data(client, page, phase, PMBUS_READ_IOUT);
+	if (ret < 0)
+		return ret;
+
+	return max_t(int, DIV_ROUND_CLOSEST(ret, data->info.phases[page]),
+		     DIV_ROUND_CLOSEST(ph_curr, data->curr_sense_gain[page]));
+}
+
+static int
+mp2975_read_phases(struct i2c_client *client, struct mp2975_data *data,
+		   int page, int phase)
+{
+	int ret;
+
+	if (page) {
+		switch (phase) {
+		case 0 ... 1:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS7_8);
+			break;
+		case 2 ... 3:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS9_10);
+			break;
+		case 4 ... 5:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS11_12);
+			break;
+		default:
+			return -ENODATA;
+		}
+	} else {
+		switch (phase) {
+		case 0 ... 1:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS1_2);
+			break;
+		case 2 ... 3:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS3_4);
+			break;
+		case 4 ... 5:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS5_6);
+			break;
+		case 6 ... 7:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS7_8);
+			break;
+		case 8 ... 9:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS9_10);
+			break;
+		case 10 ... 11:
+			ret = mp2975_read_phase(client, data, page, phase,
+						MP2975_MFR_READ_CS11_12);
+			break;
+		default:
+			return -ENODATA;
+		}
+	}
+	return ret;
+}
+
+static int mp2975_read_word_data(struct i2c_client *client, int page,
+				 int phase, int reg)
+{
+	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+	struct mp2975_data *data = to_mp2975_data(info);
+	int ret;
+
+	switch (reg) {
+	case PMBUS_OT_FAULT_LIMIT:
+		ret = mp2975_read_word_helper(client, page, phase, reg,
+					      GENMASK(7, 0));
+		break;
+	case PMBUS_VIN_OV_FAULT_LIMIT:
+		ret = mp2975_read_word_helper(client, page, phase, reg,
+					      GENMASK(7, 0));
+		if (ret < 0)
+			return ret;
+
+		ret = DIV_ROUND_CLOSEST(ret, MP2975_VIN_UV_LIMIT_UNIT);
+		break;
+	case PMBUS_VOUT_OV_FAULT_LIMIT:
+		/*
+		 * Register provides two values for over-voltage protection
+		 * threshold for fixed (ovp2) and tracking (ovp1) modes. The
+		 * minimum of these two values is provided as over-voltage
+		 * fault alarm.
+		 */
+		ret = mp2975_read_word_helper(client, page, phase,
+					      MP2975_MFR_OVP_TH_SET,
+					      GENMASK(2, 0));
+		if (ret < 0)
+			return ret;
+
+		ret = min_t(int, data->vout_max[page] + 50 * (ret + 1),
+			    data->vout_ov_fixed[page]);
+		break;
+	case PMBUS_VOUT_UV_FAULT_LIMIT:
+		ret = mp2975_read_word_helper(client, page, phase,
+					      MP2975_MFR_UVP_SET,
+					      GENMASK(2, 0));
+		if (ret < 0)
+			return ret;
+
+		ret = DIV_ROUND_CLOSEST(data->vref[page] * 10 - 50 *
+					(ret + 1) * data->vout_scale, 10);
+		break;
+	case PMBUS_READ_VOUT:
+		ret = mp2975_read_word_helper(client, page, phase, reg,
+					      GENMASK(11, 0));
+		if (ret < 0)
+			return ret;
+
+		/*
+		 * READ_VOUT can be provided in VID or direct format. The
+		 * format type is specified by bit 15 of the register
+		 * MP2975_MFR_DC_LOOP_CTRL. The driver enforces VOUT direct
+		 * format, since device allows to set the different formats for
+		 * the different rails and also all VOUT limits registers are
+		 * provided in a direct format. In case format is VID - convert
+		 * to direct.
+		 */
+		if (data->vout_format[page] == vid)
+			ret = mp2975_vid2direct(info->vrm_version[page], ret);
+		break;
+	case PMBUS_VIRT_READ_POUT_MAX:
+		ret = mp2975_read_word_helper(client, page, phase,
+					      MP2975_MFR_READ_POUT_PK,
+					      GENMASK(12, 0));
+		if (ret < 0)
+			return ret;
+
+		ret = DIV_ROUND_CLOSEST(ret, 4);
+		break;
+	case PMBUS_VIRT_READ_IOUT_MAX:
+		ret = mp2975_read_word_helper(client, page, phase,
+					      MP2975_MFR_READ_IOUT_PK,
+					      GENMASK(12, 0));
+		if (ret < 0)
+			return ret;
+
+		ret = DIV_ROUND_CLOSEST(ret, 4);
+		break;
+	case PMBUS_READ_IOUT:
+		ret = mp2975_read_phases(client, data, page, phase);
+		if (ret < 0)
+			return ret;
+
+		break;
+	case PMBUS_UT_WARN_LIMIT:
+	case PMBUS_UT_FAULT_LIMIT:
+	case PMBUS_VIN_UV_WARN_LIMIT:
+	case PMBUS_VIN_UV_FAULT_LIMIT:
+	case PMBUS_VOUT_UV_WARN_LIMIT:
+	case PMBUS_VOUT_OV_WARN_LIMIT:
+	case PMBUS_VIN_OV_WARN_LIMIT:
+	case PMBUS_IIN_OC_FAULT_LIMIT:
+	case PMBUS_IOUT_OC_LV_FAULT_LIMIT:
+	case PMBUS_IIN_OC_WARN_LIMIT:
+	case PMBUS_IOUT_OC_WARN_LIMIT:
+	case PMBUS_IOUT_OC_FAULT_LIMIT:
+	case PMBUS_IOUT_UC_FAULT_LIMIT:
+	case PMBUS_POUT_OP_FAULT_LIMIT:
+	case PMBUS_POUT_OP_WARN_LIMIT:
+	case PMBUS_PIN_OP_WARN_LIMIT:
+		return -ENXIO;
+	default:
+		return -ENODATA;
+	}
+
+	return ret;
+}
+
+static int mp2975_identify_multiphase_rail2(struct i2c_client *client)
+{
+	int ret;
+
+	/*
+	 * Identify multiphase for rail 2 - could be from 0 to 4.
+	 * In case phase number is zero – only page zero is supported
+	 */
+	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
+	if (ret < 0)
+		return ret;
+
+	/* Identify multiphase for rail 2 - could be from 0 to 4. */
+	ret = i2c_smbus_read_word_data(client, MP2975_MFR_VR_MULTI_CONFIG_R2);
+	if (ret < 0)
+		return ret;
+
+	ret &= GENMASK(2, 0);
+	return (ret >= 4) ? 4 : ret;
+}
+
+static void mp2975_set_phase_rail1(struct pmbus_driver_info *info)
+{
+	int i;
+
+	for (i = 0 ; i < info->phases[0]; i++)
+		info->pfunc[i] = PMBUS_HAVE_IOUT;
+}
+
+static void
+mp2975_set_phase_rail2(struct pmbus_driver_info *info, int num_phases)
+{
+	int i;
+
+	/* Set phases for rail 2 from upper to lower. */
+	for (i = 1; i <= num_phases; i++)
+		info->pfunc[MP2975_MAX_PHASE_RAIL1 - i] = PMBUS_HAVE_IOUT;
+}
+
+static int
+mp2975_identify_multiphase(struct i2c_client *client, struct mp2975_data *data,
+			   struct pmbus_driver_info *info)
+{
+	int num_phases2, ret;
+
+	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
+	if (ret < 0)
+		return ret;
+
+	/* Identify multiphase for rail 1 - could be from 1 to 8. */
+	ret = i2c_smbus_read_word_data(client, MP2975_MFR_VR_MULTI_CONFIG_R1);
+	if (ret <= 0)
+		return ret;
+
+	info->phases[0] = ret & GENMASK(3, 0);
+
+	/*
+	 * The device provides a total of 8 PWM pins, and can be configured
+	 * to different phase count applications for rail 1 and rail 2.
+	 * Rail 1 can be set to 8 phases, while rail 2 can only be set to 4
+	 * phases at most. When rail 1’s phase count is configured as 0, rail
+	 * 1 operates with 1-phase DCM. When rail 2 phase count is configured
+	 * as 0, rail 2 is disabled.
+	 */
+	if (info->phases[0] > MP2975_MAX_PHASE_RAIL1)
+		return -EINVAL;
+
+	mp2975_set_phase_rail1(info);
+	num_phases2 = min(MP2975_MAX_PHASE_RAIL1 - info->phases[0],
+			  MP2975_MAX_PHASE_RAIL2);
+	if (info->phases[1] && info->phases[1] <= num_phases2)
+		mp2975_set_phase_rail2(info, num_phases2);
+
+	return 0;
+}
+
+static int
+mp2975_identify_vid(struct i2c_client *client, struct mp2975_data *data,
+		    struct pmbus_driver_info *info, u32 reg, int page,
+		    u32 imvp_bit, u32 vr_bit)
+{
+	int ret;
+
+	/* Identify VID mode and step selection. */
+	ret = i2c_smbus_read_word_data(client, reg);
+	if (ret < 0)
+		return ret;
+
+	if (ret & imvp_bit) {
+		info->vrm_version[page] = imvp9;
+		data->vid_step[page] = MP2975_PROT_DEV_OV_OFF;
+	} else if (ret & vr_bit) {
+		info->vrm_version[page] = vr12;
+		data->vid_step[page] = MP2975_PROT_DEV_OV_ON;
+	} else {
+		info->vrm_version[page] = vr13;
+		data->vid_step[page] = MP2975_PROT_DEV_OV_OFF;
+	}
+
+	return 0;
+}
+
+static int
+mp2975_identify_rails_vid(struct i2c_client *client, struct mp2975_data *data,
+			  struct pmbus_driver_info *info)
+{
+	int ret;
+
+	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
+	if (ret < 0)
+		return ret;
+
+	/* Identify VID mode for rail 1. */
+	ret = mp2975_identify_vid(client, data, info,
+				  MP2975_MFR_VR_MULTI_CONFIG_R1, 0,
+				  MP2975_IMVP9_EN_R1, MP2975_VID_STEP_SEL_R1);
+	if (ret < 0)
+		return ret;
+
+	/* Identify VID mode for rail 2, if connected. */
+	if (info->phases[1])
+		ret = mp2975_identify_vid(client, data, info,
+					  MP2975_MFR_VR_MULTI_CONFIG_R2, 1,
+					  MP2975_IMVP9_EN_R2,
+					  MP2975_VID_STEP_SEL_R2);
+	return ret;
+}
+
+static int
+mp2975_current_sense_gain_get(struct i2c_client *client,
+			      struct mp2975_data *data)
+{
+	int i, ret;
+
+	/*
+	 * Obtain DrMOS current sense gain of power stage from the register
+	 * MP2975_MFR_VR_CONFIG1, bits 13-12. The value is selected as below:
+	 * 00b - 5µA/A, 01b - 8.5µA/A, 10b - 9.7µA/A, 11b - 10µA/A. Other
+	 * values are invalid.
+	 */
+	for (i = 0 ; i < data->info.pages; i++) {
+		ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, i);
+		if (ret < 0)
+			return ret;
+		ret = i2c_smbus_read_word_data(client,
+					       MP2975_MFR_VR_CONFIG1);
+		if (ret < 0)
+			return ret;
+
+		switch ((ret & MP2975_DRMOS_KCS) >> 12) {
+		case 0:
+			data->curr_sense_gain[i] = 50;
+			break;
+		case 1:
+			data->curr_sense_gain[i] = 85;
+			break;
+		case 2:
+			data->curr_sense_gain[i] = 97;
+			break;
+		default:
+			data->curr_sense_gain[i] = 100;
+			break;
+		}
+	}
+
+	return 0;
+}
+
+static int
+mp2975_vref_get(struct i2c_client *client, struct mp2975_data *data,
+		struct pmbus_driver_info *info)
+{
+	int ret;
+
+	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 3);
+	if (ret < 0)
+		return ret;
+
+	/* Get voltage reference value for rail 1. */
+	ret = i2c_smbus_read_word_data(client, MP2975_MFR_READ_VREF_R1);
+	if (ret < 0)
+		return ret;
+
+	data->vref[0] = ret * data->vid_step[0];
+
+	/* Get voltage reference value for rail 2, if connected. */
+	if (data->info.pages == MP2975_PAGE_NUM) {
+		ret = i2c_smbus_read_word_data(client, MP2975_MFR_READ_VREF_R2);
+		if (ret < 0)
+			return ret;
+
+		data->vref[1] = ret * data->vid_step[1];
+	}
+	return 0;
+}
+
+static int
+mp2975_vref_offset_get(struct i2c_client *client, struct mp2975_data *data,
+		       int page)
+{
+	int ret;
+
+	ret = i2c_smbus_read_word_data(client, MP2975_MFR_OVP_TH_SET);
+	if (ret < 0)
+		return ret;
+
+	switch ((ret & GENMASK(5, 3)) >> 3) {
+	case 1:
+		data->vref_off[page] = 140;
+		break;
+	case 2:
+		data->vref_off[page] = 220;
+		break;
+	case 4:
+		data->vref_off[page] = 400;
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int
+mp2975_vout_max_get(struct i2c_client *client, struct mp2975_data *data,
+		    struct pmbus_driver_info *info, int page)
+{
+	int ret;
+
+	/* Get maximum reference voltage of VID-DAC in VID format. */
+	ret = i2c_smbus_read_word_data(client, PMBUS_VOUT_MAX);
+	if (ret < 0)
+		return ret;
+
+	data->vout_max[page] = mp2975_vid2direct(info->vrm_version[page], ret &
+						 GENMASK(8, 0));
+	return 0;
+}
+
+static int
+mp2975_identify_vout_format(struct i2c_client *client,
+			    struct mp2975_data *data, int page)
+{
+	int ret;
+
+	ret = i2c_smbus_read_word_data(client, MP2975_MFR_DC_LOOP_CTRL);
+	if (ret < 0)
+		return ret;
+
+	if (ret & MP2975_VOUT_FORMAT)
+		data->vout_format[page] = vid;
+	else
+		data->vout_format[page] = direct;
+	return 0;
+}
+
+static int
+mp2975_vout_ov_scale_get(struct i2c_client *client, struct mp2975_data *data,
+			 struct pmbus_driver_info *info)
+{
+	int thres_dev, sense_ampl, ret;
+
+	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 0);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * Get divider for over- and under-voltage protection thresholds
+	 * configuration from the Advanced Options of Auto Phase Shedding and
+	 * decay register.
+	 */
+	ret = i2c_smbus_read_word_data(client, MP2975_MFR_APS_DECAY_ADV);
+	if (ret >= 0)
+		thres_dev = ret & MP2975_PRT_THRES_DIV_OV_EN ?
+			    MP2975_PROT_DEV_OV_ON : MP2975_PROT_DEV_OV_OFF;
+	else
+		return ret;
+
+	/* Select the gain of remote sense amplifier. */
+	ret = i2c_smbus_read_word_data(client, PMBUS_VOUT_SCALE_LOOP);
+	if (ret >= 0)
+		sense_ampl = ret & MP2975_SENSE_AMPL ? MP2975_SENSE_AMPL_HALF :
+			     MP2975_SENSE_AMPL_UNIT;
+	else
+		return ret;
+
+	data->vout_scale = sense_ampl * thres_dev;
+
+	return 0;
+}
+
+static int
+mp2975_vout_per_rail_config_get(struct i2c_client *client,
+				struct mp2975_data *data,
+				struct pmbus_driver_info *info)
+{
+	int i, ret;
+
+	for (i = 0; i < data->info.pages; i++) {
+		ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, i);
+		if (ret < 0)
+			return ret;
+
+		/* Obtain voltage reference offsets. */
+		ret = mp2975_vref_offset_get(client, data, i);
+		if (ret < 0)
+			return ret;
+
+		/* Obtain maximum voltage values. */
+		ret = mp2975_vout_max_get(client, data, info, i);
+		if (ret < 0)
+			return ret;
+
+		/*
+		 * Get VOUT format for READ_VOUT command : VID or direct.
+		 * Pages on same device can be configured with different
+		 * formats.
+		 */
+		ret = mp2975_identify_vout_format(client, data, i);
+		if (ret < 0)
+			return ret;
+
+		/*
+		 * Set over-voltage fixed value. Thresholds are provided as
+		 * fixed value, and tracking value. The minimum of them are
+		 * exposed as over-voltage critical threshold.
+		 */
+		data->vout_ov_fixed[i] = data->vref[i] +
+					 DIV_ROUND_CLOSEST(data->vref_off[i] *
+							   data->vout_scale,
+							   10);
+	}
+
+	return 0;
+}
+
+static struct pmbus_driver_info mp2975_info = {
+	.pages = 1,
+	.format[PSC_VOLTAGE_IN] = linear,
+	.format[PSC_VOLTAGE_OUT] = direct,
+	.format[PSC_TEMPERATURE] = direct,
+	.format[PSC_CURRENT_IN] = linear,
+	.format[PSC_CURRENT_OUT] = direct,
+	.format[PSC_POWER] = direct,
+	.m[PSC_TEMPERATURE] = 1,
+	.m[PSC_VOLTAGE_OUT] = 1,
+	.R[PSC_VOLTAGE_OUT] = 3,
+	.m[PSC_CURRENT_OUT] = 1,
+	.m[PSC_POWER] = 1,
+	.func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT |
+		PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
+		PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP | PMBUS_HAVE_POUT |
+		PMBUS_HAVE_PIN | PMBUS_HAVE_STATUS_INPUT | PMBUS_PHASE_VIRTUAL,
+	.read_byte_data = mp2975_read_byte_data,
+	.read_word_data = mp2975_read_word_data,
+};
+
+static int mp2975_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	struct pmbus_driver_info *info;
+	struct mp2975_data *data;
+	int ret;
+
+	data = devm_kzalloc(&client->dev, sizeof(struct mp2975_data),
+			    GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	memcpy(&data->info, &mp2975_info, sizeof(*info));
+	info = &data->info;
+
+	/* Identify multiphase configuration for rail 2. */
+	ret = mp2975_identify_multiphase_rail2(client);
+	if (ret < 0)
+		return ret;
+
+	if (ret) {
+		/* Two rails are connected. */
+		data->info.pages = MP2975_PAGE_NUM;
+		data->info.phases[1] = ret;
+		data->info.func[1] = MP2975_RAIL2_FUNC;
+	}
+
+	/* Identify multiphase configuration. */
+	ret = mp2975_identify_multiphase(client, data, info);
+	if (ret)
+		return ret;
+
+	/* Identify VID setting per rail. */
+	ret = mp2975_identify_rails_vid(client, data, info);
+	if (ret < 0)
+		return ret;
+
+	/* Obtain current sense gain of power stage. */
+	ret = mp2975_current_sense_gain_get(client, data);
+	if (ret)
+		return ret;
+
+	/* Obtain voltage reference values. */
+	ret = mp2975_vref_get(client, data, info);
+	if (ret)
+		return ret;
+
+	/* Obtain vout over-voltage scales. */
+	ret = mp2975_vout_ov_scale_get(client, data, info);
+	if (ret < 0)
+		return ret;
+
+	/* Obtain offsets, maximum and format for vout. */
+	ret = mp2975_vout_per_rail_config_get(client, data, info);
+	if (ret)
+		return ret;
+
+	return pmbus_do_probe(client, id, info);
+}
+
+static const struct i2c_device_id mp2975_id[] = {
+	{"mp2975", 0},
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, mp2975_id);
+
+static const struct of_device_id __maybe_unused mp2975_of_match[] = {
+	{.compatible = "mps,mp2975"},
+	{}
+};
+MODULE_DEVICE_TABLE(of, mp2975_of_match);
+
+static struct i2c_driver mp2975_driver = {
+	.driver = {
+		.name = "mp2975",
+		.of_match_table = of_match_ptr(mp2975_of_match),
+	},
+	.probe = mp2975_probe,
+	.remove = pmbus_do_remove,
+	.id_table = mp2975_id,
+};
+
+module_i2c_driver(mp2975_driver);
+
+MODULE_AUTHOR("Vadim Pasternak <[email protected]>");
+MODULE_DESCRIPTION("PMBus driver for MPS MP2975 device");
+MODULE_LICENSE("GPL");

Monolithic Power Systems, Inc. (MPS) dual-loop, digital, multi-phase controller.

Signed-off-by Vadim Pasternak <[email protected]>

---
v2->v3
- Fix after 'make dt_binding_check'.

---
 Documentation/devicetree/bindings/trivial-devices.yaml | 2 ++
 1 file changed, 2 insertions(+)

Monolithic Power Systems, Inc. (MPS) dual-loop, digital, multi-phase controller.

Signed-off-by Vadim Pasternak <[email protected]>

Acked-by Rob Herring <[email protected]>

---
v2->v3
- Fix after 'make dt_binding_check'.

---
 Documentation/devicetree/bindings/trivial-devices.yaml | 2 ++
 1 file changed, 2 insertions(+)

Documentation/devicetree/bindings/trivial-devices.yaml +2 -0

index 4ace8039840a..b2e994bc00af 100644
@@ -80,6 +80,8 @@ properties:
           - fsl,mpl3115
             # MPR121: Proximity Capacitive Touch Sensor Controller
           - fsl,mpr121
+            # Monolithic Power Systems Inc. multi-phase controller mp2975
+          - mps,mp2975
             # G751: Digital Temperature Sensor and Thermal Watchdog with Two-Wire Interface
           - gmt,g751
             # Infineon IR38064 Voltage Regulator