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hwmon: (pmbus) Add support for MPS Multi-phase mp2975 controller
authorVadim Pasternak <vadimp@nvidia.com>
Sat, 26 Sep 2020 20:49:56 +0000 (23:49 +0300)
committerGuenter Roeck <linux@roeck-us.net>
Sun, 4 Oct 2020 15:40:10 +0000 (08:40 -0700)
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 <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/20200926204957.10268-2-vadimp@nvidia.com
[groeck: Cleaned up a couple of error returns; fixed up API changes]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Documentation/hwmon/mp2975.rst [new file with mode: 0644]
drivers/hwmon/pmbus/Kconfig
drivers/hwmon/pmbus/Makefile
drivers/hwmon/pmbus/mp2975.c [new file with mode: 0644]

diff --git a/Documentation/hwmon/mp2975.rst b/Documentation/hwmon/mp2975.rst
new file mode 100644 (file)
index 0000000..5b0609c
--- /dev/null
@@ -0,0 +1,116 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver mp2975
+====================
+
+Supported chips:
+
+  * MPS MP12254
+
+    Prefix: 'mp2975'
+
+Author:
+
+       Vadim Pasternak <vadimp@nvidia.com>
+
+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**
index db90e00..a25faf6 100644 (file)
@@ -211,6 +211,15 @@ 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
index da41d22..4c97ad0 100644 (file)
@@ -24,6 +24,7 @@ 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
diff --git a/drivers/hwmon/pmbus/mp2975.c b/drivers/hwmon/pmbus/mp2975.c
new file mode 100644 (file)
index 0000000..1c3e2a9
--- /dev/null
@@ -0,0 +1,769 @@
+// 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)
+               return ret;
+       thres_dev = ret & MP2975_PRT_THRES_DIV_OV_EN ? MP2975_PROT_DEV_OV_ON :
+                                                      MP2975_PROT_DEV_OV_OFF;
+
+       /* Select the gain of remote sense amplifier. */
+       ret = i2c_smbus_read_word_data(client, PMBUS_VOUT_SCALE_LOOP);
+       if (ret < 0)
+               return ret;
+       sense_ampl = ret & MP2975_SENSE_AMPL ? MP2975_SENSE_AMPL_HALF :
+                                              MP2975_SENSE_AMPL_UNIT;
+
+       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)
+{
+       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, 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_new = mp2975_probe,
+       .remove = pmbus_do_remove,
+       .id_table = mp2975_id,
+};
+
+module_i2c_driver(mp2975_driver);
+
+MODULE_AUTHOR("Vadim Pasternak <vadimp@nvidia.com>");
+MODULE_DESCRIPTION("PMBus driver for MPS MP2975 device");
+MODULE_LICENSE("GPL");