hw/i2c: add support for PMBus

QEMU has support for SMBus devices, and PMBus is a more specific
implementation of SMBus. The additions made in this commit makes it easier to
add new PMBus devices to QEMU.

https://pmbus.org/specification-archives/

Reviewed-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Hao Wu <wuhaotsh@google.com>
Signed-off-by: Titus Rwantare <titusr@google.com>
Message-Id: <20210708172556.1868139-2-titusr@google.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>

3 files changed, 1617 insertions, 0 deletions

diff --git a/hw/i2c/Kconfig b/hw/i2c/Kconfig
index 8d120a2..8217cb5 100644
--- a/hw/i2c/Kconfig
+++ b/hw/i2c/Kconfig
@@ -32,3 +32,7 @@ config MPC_I2C
 config PCA954X
     bool
     select I2C
+
+config PMBUS
+    bool
+    select SMBUS
diff --git a/hw/i2c/meson.build b/hw/i2c/meson.build
index dd3aef0..d3df273 100644
--- a/hw/i2c/meson.build
+++ b/hw/i2c/meson.build
@@ -15,4 +15,5 @@ i2c_ss.add(when: 'CONFIG_VERSATILE_I2C', if_true: files('versatile_i2c.c'))
 i2c_ss.add(when: 'CONFIG_OMAP', if_true: files('omap_i2c.c'))
 i2c_ss.add(when: 'CONFIG_PPC4XX', if_true: files('ppc4xx_i2c.c'))
 i2c_ss.add(when: 'CONFIG_PCA954X', if_true: files('i2c_mux_pca954x.c'))
+i2c_ss.add(when: 'CONFIG_PMBUS', if_true: files('pmbus_device.c'))
 softmmu_ss.add_all(when: 'CONFIG_I2C', if_true: i2c_ss)
diff --git a/hw/i2c/pmbus_device.c b/hw/i2c/pmbus_device.c
new file mode 100644
index 0000000..24f8f52
--- /dev/null
+++ b/hw/i2c/pmbus_device.c
@@ -0,0 +1,1612 @@
+/*
+ * PMBus wrapper over SMBus
+ *
+ * Copyright 2021 Google LLC
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include <math.h>
+#include <string.h>
+#include "hw/i2c/pmbus_device.h"
+#include "migration/vmstate.h"
+#include "qemu/module.h"
+#include "qemu/log.h"
+
+uint16_t pmbus_data2direct_mode(PMBusCoefficients c, uint32_t value)
+{
+    /* R is usually negative to fit large readings into 16 bits */
+    uint16_t y = (c.m * value + c.b) * pow(10, c.R);
+    return y;
+}
+
+uint32_t pmbus_direct_mode2data(PMBusCoefficients c, uint16_t value)
+{
+    /* X = (Y * 10^-R - b) / m */
+    uint32_t x = (value / pow(10, c.R) - c.b) / c.m;
+    return x;
+}
+
+void pmbus_send(PMBusDevice *pmdev, const uint8_t *data, uint16_t len)
+{
+    if (pmdev->out_buf_len + len > SMBUS_DATA_MAX_LEN) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "PMBus device tried to send too much data");
+        len = 0;
+    }
+
+    for (int i = len - 1; i >= 0; i--) {
+        pmdev->out_buf[i + pmdev->out_buf_len] = data[len - i - 1];
+    }
+    pmdev->out_buf_len += len;
+}
+
+/* Internal only, convert unsigned ints to the little endian bus */
+static void pmbus_send_uint(PMBusDevice *pmdev, uint64_t data, uint8_t size)
+{
+    uint8_t bytes[8];
+    g_assert(size <= 8);
+
+    for (int i = 0; i < size; i++) {
+        bytes[i] = data & 0xFF;
+        data = data >> 8;
+    }
+    pmbus_send(pmdev, bytes, size);
+}
+
+void pmbus_send8(PMBusDevice *pmdev, uint8_t data)
+{
+    pmbus_send_uint(pmdev, data, 1);
+}
+
+void pmbus_send16(PMBusDevice *pmdev, uint16_t data)
+{
+    pmbus_send_uint(pmdev, data, 2);
+}
+
+void pmbus_send32(PMBusDevice *pmdev, uint32_t data)
+{
+    pmbus_send_uint(pmdev, data, 4);
+}
+
+void pmbus_send64(PMBusDevice *pmdev, uint64_t data)
+{
+    pmbus_send_uint(pmdev, data, 8);
+}
+
+void pmbus_send_string(PMBusDevice *pmdev, const char *data)
+{
+    size_t len = strlen(data);
+    g_assert(len > 0);
+    g_assert(len + pmdev->out_buf_len < SMBUS_DATA_MAX_LEN);
+    pmdev->out_buf[len + pmdev->out_buf_len] = len;
+
+    for (int i = len - 1; i >= 0; i--) {
+        pmdev->out_buf[i + pmdev->out_buf_len] = data[len - 1 - i];
+    }
+    pmdev->out_buf_len += len + 1;
+}
+
+
+static uint64_t pmbus_receive_uint(const uint8_t *buf, uint8_t len)
+{
+    uint64_t ret = 0;
+
+    /* Exclude command code from return value */
+    buf++;
+    len--;
+
+    for (int i = len - 1; i >= 0; i--) {
+        ret = ret << 8 | buf[i];
+    }
+    return ret;
+}
+
+uint8_t pmbus_receive8(PMBusDevice *pmdev)
+{
+    if (pmdev->in_buf_len - 1 != 1) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: length mismatch. Expected 1 byte, got %d bytes\n",
+                      __func__, pmdev->in_buf_len - 1);
+    }
+    return pmbus_receive_uint(pmdev->in_buf, pmdev->in_buf_len);
+}
+
+uint16_t pmbus_receive16(PMBusDevice *pmdev)
+{
+    if (pmdev->in_buf_len - 1 != 2) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: length mismatch. Expected 2 bytes, got %d bytes\n",
+                      __func__, pmdev->in_buf_len - 1);
+    }
+    return pmbus_receive_uint(pmdev->in_buf, pmdev->in_buf_len);
+}
+
+uint32_t pmbus_receive32(PMBusDevice *pmdev)
+{
+    if (pmdev->in_buf_len - 1 != 4) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: length mismatch. Expected 4 bytes, got %d bytes\n",
+                      __func__, pmdev->in_buf_len - 1);
+    }
+    return pmbus_receive_uint(pmdev->in_buf, pmdev->in_buf_len);
+}
+
+uint64_t pmbus_receive64(PMBusDevice *pmdev)
+{
+    if (pmdev->in_buf_len - 1 != 8) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: length mismatch. Expected 8 bytes, got %d bytes\n",
+                      __func__, pmdev->in_buf_len - 1);
+    }
+    return pmbus_receive_uint(pmdev->in_buf, pmdev->in_buf_len);
+}
+
+static uint8_t pmbus_out_buf_pop(PMBusDevice *pmdev)
+{
+    if (pmdev->out_buf_len == 0) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: tried to read from empty buffer",
+                      __func__);
+        return 0xFF;
+    }
+    uint8_t data = pmdev->out_buf[pmdev->out_buf_len - 1];
+    pmdev->out_buf_len--;
+    return data;
+}
+
+static void pmbus_quick_cmd(SMBusDevice *smd, uint8_t read)
+{
+    PMBusDevice *pmdev = PMBUS_DEVICE(smd);
+    PMBusDeviceClass *pmdc = PMBUS_DEVICE_GET_CLASS(pmdev);
+
+    if (pmdc->quick_cmd) {
+        pmdc->quick_cmd(pmdev, read);
+    }
+}
+
+static void pmbus_pages_alloc(PMBusDevice *pmdev)
+{
+    /* some PMBus devices don't use the PAGE command, so they get 1 page */
+    PMBusDeviceClass *k = PMBUS_DEVICE_GET_CLASS(pmdev);
+    if (k->device_num_pages == 0) {
+        k->device_num_pages = 1;
+    }
+    pmdev->num_pages = k->device_num_pages;
+    pmdev->pages = g_new0(PMBusPage, k->device_num_pages);
+}
+
+void pmbus_check_limits(PMBusDevice *pmdev)
+{
+    for (int i = 0; i < pmdev->num_pages; i++) {
+        if ((pmdev->pages[i].operation & PB_OP_ON) == 0) {
+            continue;   /* don't check powered off devices */
+        }
+
+        if (pmdev->pages[i].read_vout > pmdev->pages[i].vout_ov_fault_limit) {
+            pmdev->pages[i].status_word |= PB_STATUS_VOUT;
+            pmdev->pages[i].status_vout |= PB_STATUS_VOUT_OV_FAULT;
+        }
+
+        if (pmdev->pages[i].read_vout > pmdev->pages[i].vout_ov_warn_limit) {
+            pmdev->pages[i].status_word |= PB_STATUS_VOUT;
+            pmdev->pages[i].status_vout |= PB_STATUS_VOUT_OV_WARN;
+        }
+
+        if (pmdev->pages[i].read_vout < pmdev->pages[i].vout_uv_warn_limit) {
+            pmdev->pages[i].status_word |= PB_STATUS_VOUT;
+            pmdev->pages[i].status_vout |= PB_STATUS_VOUT_UV_WARN;
+        }
+
+        if (pmdev->pages[i].read_vout < pmdev->pages[i].vout_uv_fault_limit) {
+            pmdev->pages[i].status_word |= PB_STATUS_VOUT;
+            pmdev->pages[i].status_vout |= PB_STATUS_VOUT_UV_FAULT;
+        }
+
+        if (pmdev->pages[i].read_vin > pmdev->pages[i].vin_ov_warn_limit) {
+            pmdev->pages[i].status_word |= PB_STATUS_INPUT;
+            pmdev->pages[i].status_input |= PB_STATUS_INPUT_VIN_OV_WARN;
+        }
+
+        if (pmdev->pages[i].read_vin < pmdev->pages[i].vin_uv_warn_limit) {
+            pmdev->pages[i].status_word |= PB_STATUS_INPUT;
+            pmdev->pages[i].status_input |= PB_STATUS_INPUT_VIN_UV_WARN;
+        }
+
+        if (pmdev->pages[i].read_iout > pmdev->pages[i].iout_oc_warn_limit) {
+            pmdev->pages[i].status_word |= PB_STATUS_IOUT_POUT;
+            pmdev->pages[i].status_iout |= PB_STATUS_IOUT_OC_WARN;
+        }
+
+        if (pmdev->pages[i].read_iout > pmdev->pages[i].iout_oc_fault_limit) {
+            pmdev->pages[i].status_word |= PB_STATUS_IOUT_POUT;
+            pmdev->pages[i].status_iout |= PB_STATUS_IOUT_OC_FAULT;
+        }
+
+        if (pmdev->pages[i].read_pin > pmdev->pages[i].pin_op_warn_limit) {
+            pmdev->pages[i].status_word |= PB_STATUS_INPUT;
+            pmdev->pages[i].status_input |= PB_STATUS_INPUT_PIN_OP_WARN;
+        }
+
+        if (pmdev->pages[i].read_temperature_1
+                > pmdev->pages[i].ot_fault_limit) {
+            pmdev->pages[i].status_word |= PB_STATUS_TEMPERATURE;
+            pmdev->pages[i].status_temperature |= PB_STATUS_OT_FAULT;
+        }
+
+        if (pmdev->pages[i].read_temperature_1
+                > pmdev->pages[i].ot_warn_limit) {
+            pmdev->pages[i].status_word |= PB_STATUS_TEMPERATURE;
+            pmdev->pages[i].status_temperature |= PB_STATUS_OT_WARN;
+        }
+    }
+}
+
+static uint8_t pmbus_receive_byte(SMBusDevice *smd)
+{
+    PMBusDevice *pmdev = PMBUS_DEVICE(smd);
+    PMBusDeviceClass *pmdc = PMBUS_DEVICE_GET_CLASS(pmdev);
+    uint8_t ret = 0xFF;
+    uint8_t index = pmdev->page;
+
+    if (pmdev->out_buf_len != 0) {
+        ret = pmbus_out_buf_pop(pmdev);
+        return ret;
+    }
+
+    switch (pmdev->code) {
+    case PMBUS_PAGE:
+        pmbus_send8(pmdev, pmdev->page);
+        break;
+
+    case PMBUS_OPERATION:                 /* R/W byte */
+        pmbus_send8(pmdev, pmdev->pages[index].operation);
+        break;
+
+    case PMBUS_ON_OFF_CONFIG:             /* R/W byte */
+        pmbus_send8(pmdev, pmdev->pages[index].on_off_config);
+        break;
+
+    case PMBUS_PHASE:                     /* R/W byte */
+        pmbus_send8(pmdev, pmdev->pages[index].phase);
+        break;
+
+    case PMBUS_WRITE_PROTECT:             /* R/W byte */
+        pmbus_send8(pmdev, pmdev->pages[index].write_protect);
+        break;
+
+    case PMBUS_CAPABILITY:
+        pmbus_send8(pmdev, pmdev->capability);
+        break;
+
+    case PMBUS_VOUT_MODE:                 /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT_MODE) {
+            pmbus_send8(pmdev, pmdev->pages[index].vout_mode);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VOUT_COMMAND:              /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].vout_command);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VOUT_TRIM:                 /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].vout_trim);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VOUT_CAL_OFFSET:           /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].vout_cal_offset);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VOUT_MAX:                  /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].vout_max);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VOUT_MARGIN_HIGH:          /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT_MARGIN) {
+            pmbus_send16(pmdev, pmdev->pages[index].vout_margin_high);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VOUT_MARGIN_LOW:           /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT_MARGIN) {
+            pmbus_send16(pmdev, pmdev->pages[index].vout_margin_low);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VOUT_TRANSITION_RATE:      /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].vout_transition_rate);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VOUT_DROOP:                /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].vout_droop);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VOUT_SCALE_LOOP:           /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].vout_scale_loop);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VOUT_SCALE_MONITOR:        /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].vout_scale_monitor);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    /* TODO: implement coefficients support */
+
+    case PMBUS_POUT_MAX:                  /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_POUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].pout_max);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VIN_ON:                    /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VIN) {
+            pmbus_send16(pmdev, pmdev->pages[index].vin_on);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VIN_OFF:                   /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VIN) {
+            pmbus_send16(pmdev, pmdev->pages[index].vin_off);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_IOUT_CAL_GAIN:             /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_IOUT_GAIN) {
+            pmbus_send16(pmdev, pmdev->pages[index].iout_cal_gain);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VOUT_OV_FAULT_LIMIT:       /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].vout_ov_fault_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VOUT_OV_FAULT_RESPONSE:    /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmbus_send8(pmdev, pmdev->pages[index].vout_ov_fault_response);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VOUT_OV_WARN_LIMIT:        /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].vout_ov_warn_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VOUT_UV_WARN_LIMIT:        /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].vout_uv_warn_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VOUT_UV_FAULT_LIMIT:       /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].vout_uv_fault_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VOUT_UV_FAULT_RESPONSE:    /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmbus_send8(pmdev, pmdev->pages[index].vout_uv_fault_response);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_IOUT_OC_FAULT_LIMIT:       /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_IOUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].iout_oc_fault_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_IOUT_OC_FAULT_RESPONSE:    /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_IOUT) {
+            pmbus_send8(pmdev, pmdev->pages[index].iout_oc_fault_response);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_IOUT_OC_LV_FAULT_LIMIT:    /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_IOUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].iout_oc_lv_fault_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_IOUT_OC_LV_FAULT_RESPONSE: /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_IOUT) {
+            pmbus_send8(pmdev, pmdev->pages[index].iout_oc_lv_fault_response);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_IOUT_OC_WARN_LIMIT:        /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_IOUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].iout_oc_warn_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_IOUT_UC_FAULT_LIMIT:       /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_IOUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].iout_uc_fault_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_IOUT_UC_FAULT_RESPONSE:    /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_IOUT) {
+            pmbus_send8(pmdev, pmdev->pages[index].iout_uc_fault_response);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_OT_FAULT_LIMIT:            /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_TEMPERATURE) {
+            pmbus_send16(pmdev, pmdev->pages[index].ot_fault_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_OT_FAULT_RESPONSE:         /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_TEMPERATURE) {
+            pmbus_send8(pmdev, pmdev->pages[index].ot_fault_response);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_OT_WARN_LIMIT:             /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_TEMPERATURE) {
+            pmbus_send16(pmdev, pmdev->pages[index].ot_warn_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_UT_WARN_LIMIT:             /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_TEMPERATURE) {
+            pmbus_send16(pmdev, pmdev->pages[index].ut_warn_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_UT_FAULT_LIMIT:            /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_TEMPERATURE) {
+            pmbus_send16(pmdev, pmdev->pages[index].ut_fault_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_UT_FAULT_RESPONSE:         /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_TEMPERATURE) {
+            pmbus_send8(pmdev, pmdev->pages[index].ut_fault_response);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VIN_OV_FAULT_LIMIT:        /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VIN) {
+            pmbus_send16(pmdev, pmdev->pages[index].vin_ov_fault_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VIN_OV_FAULT_RESPONSE:     /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_VIN) {
+            pmbus_send8(pmdev, pmdev->pages[index].vin_ov_fault_response);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VIN_OV_WARN_LIMIT:         /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VIN) {
+            pmbus_send16(pmdev, pmdev->pages[index].vin_ov_warn_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VIN_UV_WARN_LIMIT:         /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VIN) {
+            pmbus_send16(pmdev, pmdev->pages[index].vin_uv_warn_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VIN_UV_FAULT_LIMIT:        /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VIN) {
+            pmbus_send16(pmdev, pmdev->pages[index].vin_uv_fault_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_VIN_UV_FAULT_RESPONSE:     /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_VIN) {
+            pmbus_send8(pmdev, pmdev->pages[index].vin_uv_fault_response);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_IIN_OC_FAULT_LIMIT:        /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_IIN) {
+            pmbus_send16(pmdev, pmdev->pages[index].iin_oc_fault_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_IIN_OC_FAULT_RESPONSE:     /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_IIN) {
+            pmbus_send8(pmdev, pmdev->pages[index].iin_oc_fault_response);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_IIN_OC_WARN_LIMIT:         /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_IIN) {
+            pmbus_send16(pmdev, pmdev->pages[index].iin_oc_warn_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_POUT_OP_FAULT_LIMIT:       /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_POUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].pout_op_fault_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_POUT_OP_FAULT_RESPONSE:    /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_POUT) {
+            pmbus_send8(pmdev, pmdev->pages[index].pout_op_fault_response);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_POUT_OP_WARN_LIMIT:        /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_POUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].pout_op_warn_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_PIN_OP_WARN_LIMIT:         /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_PIN) {
+            pmbus_send16(pmdev, pmdev->pages[index].pin_op_warn_limit);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_STATUS_BYTE:               /* R/W byte */
+        pmbus_send8(pmdev, pmdev->pages[index].status_word & 0xFF);
+        break;
+
+    case PMBUS_STATUS_WORD:               /* R/W word */
+        pmbus_send16(pmdev, pmdev->pages[index].status_word);
+        break;
+
+    case PMBUS_STATUS_VOUT:               /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmbus_send8(pmdev, pmdev->pages[index].status_vout);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_STATUS_IOUT:               /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_IOUT) {
+            pmbus_send8(pmdev, pmdev->pages[index].status_iout);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_STATUS_INPUT:              /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_VIN ||
+            pmdev->pages[index].page_flags & PB_HAS_IIN ||
+            pmdev->pages[index].page_flags & PB_HAS_PIN) {
+            pmbus_send8(pmdev, pmdev->pages[index].status_input);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_STATUS_TEMPERATURE:        /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_TEMPERATURE) {
+            pmbus_send8(pmdev, pmdev->pages[index].status_temperature);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_STATUS_CML:                /* R/W byte */
+        pmbus_send8(pmdev, pmdev->pages[index].status_cml);
+        break;
+
+    case PMBUS_STATUS_OTHER:              /* R/W byte */
+        pmbus_send8(pmdev, pmdev->pages[index].status_other);
+        break;
+
+    case PMBUS_READ_EIN:                  /* Read-Only block 5 bytes */
+        if (pmdev->pages[index].page_flags & PB_HAS_EIN) {
+            pmbus_send(pmdev, pmdev->pages[index].read_ein, 5);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_READ_EOUT:                 /* Read-Only block 5 bytes */
+        if (pmdev->pages[index].page_flags & PB_HAS_EOUT) {
+            pmbus_send(pmdev, pmdev->pages[index].read_eout, 5);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_READ_VIN:                  /* Read-Only word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VIN) {
+            pmbus_send16(pmdev, pmdev->pages[index].read_vin);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_READ_IIN:                  /* Read-Only word */
+        if (pmdev->pages[index].page_flags & PB_HAS_IIN) {
+            pmbus_send16(pmdev, pmdev->pages[index].read_iin);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_READ_VOUT:                 /* Read-Only word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].read_vout);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_READ_IOUT:                 /* Read-Only word */
+        if (pmdev->pages[index].page_flags & PB_HAS_IOUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].read_iout);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_READ_TEMPERATURE_1:        /* Read-Only word */
+        if (pmdev->pages[index].page_flags & PB_HAS_TEMPERATURE) {
+            pmbus_send16(pmdev, pmdev->pages[index].read_temperature_1);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_READ_TEMPERATURE_2:        /* Read-Only word */
+        if (pmdev->pages[index].page_flags & PB_HAS_TEMP2) {
+            pmbus_send16(pmdev, pmdev->pages[index].read_temperature_2);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_READ_TEMPERATURE_3:        /* Read-Only word */
+        if (pmdev->pages[index].page_flags & PB_HAS_TEMP3) {
+            pmbus_send16(pmdev, pmdev->pages[index].read_temperature_3);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_READ_POUT:                 /* Read-Only word */
+        if (pmdev->pages[index].page_flags & PB_HAS_POUT) {
+            pmbus_send16(pmdev, pmdev->pages[index].read_pout);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_READ_PIN:                  /* Read-Only word */
+        if (pmdev->pages[index].page_flags & PB_HAS_PIN) {
+            pmbus_send16(pmdev, pmdev->pages[index].read_pin);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_REVISION:                  /* Read-Only byte */
+        pmbus_send8(pmdev, pmdev->pages[index].revision);
+        break;
+
+    case PMBUS_MFR_ID:                    /* R/W block */
+        if (pmdev->pages[index].page_flags & PB_HAS_MFR_INFO) {
+            pmbus_send_string(pmdev, pmdev->pages[index].mfr_id);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_MFR_MODEL:                 /* R/W block */
+        if (pmdev->pages[index].page_flags & PB_HAS_MFR_INFO) {
+            pmbus_send_string(pmdev, pmdev->pages[index].mfr_model);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_MFR_REVISION:              /* R/W block */
+        if (pmdev->pages[index].page_flags & PB_HAS_MFR_INFO) {
+            pmbus_send_string(pmdev, pmdev->pages[index].mfr_revision);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_MFR_LOCATION:              /* R/W block */
+        if (pmdev->pages[index].page_flags & PB_HAS_MFR_INFO) {
+            pmbus_send_string(pmdev, pmdev->pages[index].mfr_location);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_MFR_VIN_MIN:               /* Read-Only word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VIN_RATING) {
+            pmbus_send16(pmdev, pmdev->pages[index].mfr_vin_min);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_MFR_VIN_MAX:               /* Read-Only word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VIN_RATING) {
+            pmbus_send16(pmdev, pmdev->pages[index].mfr_vin_max);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_MFR_IIN_MAX:               /* Read-Only word */
+        if (pmdev->pages[index].page_flags & PB_HAS_IIN_RATING) {
+            pmbus_send16(pmdev, pmdev->pages[index].mfr_iin_max);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_MFR_PIN_MAX:               /* Read-Only word */
+        if (pmdev->pages[index].page_flags & PB_HAS_PIN_RATING) {
+            pmbus_send16(pmdev, pmdev->pages[index].mfr_pin_max);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_MFR_VOUT_MIN:              /* Read-Only word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT_RATING) {
+            pmbus_send16(pmdev, pmdev->pages[index].mfr_vout_min);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_MFR_VOUT_MAX:              /* Read-Only word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT_RATING) {
+            pmbus_send16(pmdev, pmdev->pages[index].mfr_vout_max);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_MFR_IOUT_MAX:              /* Read-Only word */
+        if (pmdev->pages[index].page_flags & PB_HAS_IOUT_RATING) {
+            pmbus_send16(pmdev, pmdev->pages[index].mfr_iout_max);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_MFR_POUT_MAX:              /* Read-Only word */
+        if (pmdev->pages[index].page_flags & PB_HAS_POUT_RATING) {
+            pmbus_send16(pmdev, pmdev->pages[index].mfr_pout_max);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_MFR_MAX_TEMP_1:            /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_TEMP_RATING) {
+            pmbus_send16(pmdev, pmdev->pages[index].mfr_max_temp_1);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_MFR_MAX_TEMP_2:            /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_TEMP_RATING) {
+            pmbus_send16(pmdev, pmdev->pages[index].mfr_max_temp_2);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_MFR_MAX_TEMP_3:            /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_TEMP_RATING) {
+            pmbus_send16(pmdev, pmdev->pages[index].mfr_max_temp_3);
+        } else {
+            goto passthough;
+        }
+        break;
+
+    case PMBUS_CLEAR_FAULTS:              /* Send Byte */
+    case PMBUS_PAGE_PLUS_WRITE:           /* Block Write-only */
+    case PMBUS_STORE_DEFAULT_ALL:         /* Send Byte */
+    case PMBUS_RESTORE_DEFAULT_ALL:       /* Send Byte */
+    case PMBUS_STORE_DEFAULT_CODE:        /* Write-only Byte */
+    case PMBUS_RESTORE_DEFAULT_CODE:      /* Write-only Byte */
+    case PMBUS_STORE_USER_ALL:            /* Send Byte */
+    case PMBUS_RESTORE_USER_ALL:          /* Send Byte */
+    case PMBUS_STORE_USER_CODE:           /* Write-only Byte */
+    case PMBUS_RESTORE_USER_CODE:         /* Write-only Byte */
+    case PMBUS_QUERY:                     /* Write-Only */
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: reading from write only register 0x%02x\n",
+                      __func__, pmdev->code);
+        break;
+
+passthough:
+    default:
+        /* Pass through read request if not handled */
+        if (pmdc->receive_byte) {
+            ret = pmdc->receive_byte(pmdev);
+        }
+        break;
+    }
+
+    if (pmdev->out_buf_len != 0) {
+        ret = pmbus_out_buf_pop(pmdev);
+        return ret;
+    }
+
+    return ret;
+}
+
+/*
+ * PMBus clear faults command applies to all status registers, existing faults
+ * should separately get re-asserted.
+ */
+static void pmbus_clear_faults(PMBusDevice *pmdev)
+{
+    for (uint8_t i = 0; i < pmdev->num_pages; i++) {
+        pmdev->pages[i].status_word = 0;
+        pmdev->pages[i].status_vout = 0;
+        pmdev->pages[i].status_iout = 0;
+        pmdev->pages[i].status_input = 0;
+        pmdev->pages[i].status_temperature = 0;
+        pmdev->pages[i].status_cml = 0;
+        pmdev->pages[i].status_other = 0;
+        pmdev->pages[i].status_mfr_specific = 0;
+        pmdev->pages[i].status_fans_1_2 = 0;
+        pmdev->pages[i].status_fans_3_4 = 0;
+    }
+
+}
+
+/*
+ * PMBus operation is used to turn On and Off PSUs
+ * Therefore, default value for the Operation should be PB_OP_ON or 0x80
+ */
+static void pmbus_operation(PMBusDevice *pmdev)
+{
+    uint8_t index = pmdev->page;
+    if ((pmdev->pages[index].operation & PB_OP_ON) == 0) {
+        pmdev->pages[index].read_vout = 0;
+        pmdev->pages[index].read_iout = 0;
+        pmdev->pages[index].read_pout = 0;
+        return;
+    }
+
+    if (pmdev->pages[index].operation & (PB_OP_ON | PB_OP_MARGIN_HIGH)) {
+        pmdev->pages[index].read_vout = pmdev->pages[index].vout_margin_high;
+    }
+
+    if (pmdev->pages[index].operation & (PB_OP_ON | PB_OP_MARGIN_LOW)) {
+        pmdev->pages[index].read_vout = pmdev->pages[index].vout_margin_low;
+    }
+    pmbus_check_limits(pmdev);
+}
+
+static int pmbus_write_data(SMBusDevice *smd, uint8_t *buf, uint8_t len)
+{
+    PMBusDevice *pmdev = PMBUS_DEVICE(smd);
+    PMBusDeviceClass *pmdc = PMBUS_DEVICE_GET_CLASS(pmdev);
+    int ret = 0;
+    uint8_t index;
+
+    if (len == 0) {
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: writing empty data\n", __func__);
+        return -1;
+    }
+
+    if (!pmdev->pages) { /* allocate memory for pages on first use */
+        pmbus_pages_alloc(pmdev);
+    }
+
+    pmdev->in_buf_len = len;
+    pmdev->in_buf = buf;
+
+    pmdev->code = buf[0]; /* PMBus command code */
+    if (len == 1) { /* Single length writes are command codes only */
+        return 0;
+    }
+
+    if (pmdev->code == PMBUS_PAGE) {
+        pmdev->page = pmbus_receive8(pmdev);
+        return 0;
+    }
+    /* loop through all the pages when 0xFF is received */
+    if (pmdev->page == PB_ALL_PAGES) {
+        for (int i = 0; i < pmdev->num_pages; i++) {
+            pmdev->page = i;
+            pmbus_write_data(smd, buf, len);
+        }
+        pmdev->page = PB_ALL_PAGES;
+        return 0;
+    }
+
+    index = pmdev->page;
+
+    switch (pmdev->code) {
+    case PMBUS_OPERATION:                 /* R/W byte */
+        pmdev->pages[index].operation = pmbus_receive8(pmdev);
+        pmbus_operation(pmdev);
+        break;
+
+    case PMBUS_ON_OFF_CONFIG:             /* R/W byte */
+        pmdev->pages[index].on_off_config = pmbus_receive8(pmdev);
+        break;
+
+    case PMBUS_CLEAR_FAULTS:              /* Send Byte */
+        pmbus_clear_faults(pmdev);
+        break;
+
+    case PMBUS_PHASE:                     /* R/W byte */
+        pmdev->pages[index].phase = pmbus_receive8(pmdev);
+        break;
+
+    case PMBUS_PAGE_PLUS_WRITE:           /* Block Write-only */
+    case PMBUS_WRITE_PROTECT:             /* R/W byte */
+        pmdev->pages[index].write_protect = pmbus_receive8(pmdev);
+        break;
+
+    case PMBUS_VOUT_MODE:                 /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT_MODE) {
+            pmdev->pages[index].vout_mode = pmbus_receive8(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VOUT_COMMAND:              /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmdev->pages[index].vout_command = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VOUT_TRIM:                 /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmdev->pages[index].vout_trim = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VOUT_CAL_OFFSET:           /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmdev->pages[index].vout_cal_offset = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VOUT_MAX:                  /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmdev->pages[index].vout_max = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VOUT_MARGIN_HIGH:          /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT_MARGIN) {
+            pmdev->pages[index].vout_margin_high = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VOUT_MARGIN_LOW:           /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT_MARGIN) {
+            pmdev->pages[index].vout_margin_low = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VOUT_TRANSITION_RATE:      /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmdev->pages[index].vout_transition_rate = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VOUT_DROOP:                /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmdev->pages[index].vout_droop = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VOUT_SCALE_LOOP:           /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmdev->pages[index].vout_scale_loop = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VOUT_SCALE_MONITOR:        /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmdev->pages[index].vout_scale_monitor = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_POUT_MAX:                  /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmdev->pages[index].pout_max = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VIN_ON:                    /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VIN) {
+            pmdev->pages[index].vin_on = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VIN_OFF:                   /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VIN) {
+            pmdev->pages[index].vin_off = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_IOUT_CAL_GAIN:             /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_IOUT_GAIN) {
+            pmdev->pages[index].iout_cal_gain = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VOUT_OV_FAULT_LIMIT:       /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmdev->pages[index].vout_ov_fault_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VOUT_OV_FAULT_RESPONSE:    /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmdev->pages[index].vout_ov_fault_response = pmbus_receive8(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VOUT_OV_WARN_LIMIT:        /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmdev->pages[index].vout_ov_warn_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VOUT_UV_WARN_LIMIT:        /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmdev->pages[index].vout_uv_warn_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VOUT_UV_FAULT_LIMIT:       /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmdev->pages[index].vout_uv_fault_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VOUT_UV_FAULT_RESPONSE:    /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmdev->pages[index].vout_uv_fault_response = pmbus_receive8(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_IOUT_OC_FAULT_LIMIT:       /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_IOUT) {
+            pmdev->pages[index].iout_oc_fault_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_IOUT_OC_FAULT_RESPONSE:    /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_IOUT) {
+            pmdev->pages[index].iout_oc_fault_response = pmbus_receive8(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_IOUT_OC_LV_FAULT_LIMIT:    /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_IOUT) {
+            pmdev->pages[index].iout_oc_lv_fault_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_IOUT_OC_LV_FAULT_RESPONSE: /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_IOUT) {
+            pmdev->pages[index].iout_oc_lv_fault_response
+                = pmbus_receive8(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_IOUT_OC_WARN_LIMIT:        /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_IOUT) {
+            pmdev->pages[index].iout_oc_warn_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_IOUT_UC_FAULT_LIMIT:       /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_IOUT) {
+            pmdev->pages[index].iout_uc_fault_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_IOUT_UC_FAULT_RESPONSE:    /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_IOUT) {
+            pmdev->pages[index].iout_uc_fault_response = pmbus_receive8(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_OT_FAULT_LIMIT:            /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_TEMPERATURE) {
+            pmdev->pages[index].ot_fault_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_OT_FAULT_RESPONSE:         /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_TEMPERATURE) {
+            pmdev->pages[index].ot_fault_response = pmbus_receive8(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_OT_WARN_LIMIT:             /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_TEMPERATURE) {
+            pmdev->pages[index].ot_warn_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_UT_WARN_LIMIT:             /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_TEMPERATURE) {
+            pmdev->pages[index].ut_warn_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_UT_FAULT_LIMIT:            /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_TEMPERATURE) {
+            pmdev->pages[index].ut_fault_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_UT_FAULT_RESPONSE:         /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_TEMPERATURE) {
+            pmdev->pages[index].ut_fault_response = pmbus_receive8(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VIN_OV_FAULT_LIMIT:        /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VIN) {
+            pmdev->pages[index].vin_ov_fault_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VIN_OV_FAULT_RESPONSE:     /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_VIN) {
+            pmdev->pages[index].vin_ov_fault_response = pmbus_receive8(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VIN_OV_WARN_LIMIT:         /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VIN) {
+            pmdev->pages[index].vin_ov_warn_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VIN_UV_WARN_LIMIT:         /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VIN) {
+            pmdev->pages[index].vin_uv_warn_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VIN_UV_FAULT_LIMIT:        /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VIN) {
+            pmdev->pages[index].vin_uv_fault_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_VIN_UV_FAULT_RESPONSE:     /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_VIN) {
+            pmdev->pages[index].vin_uv_fault_response = pmbus_receive8(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_IIN_OC_FAULT_LIMIT:        /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_IIN) {
+            pmdev->pages[index].iin_oc_fault_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_IIN_OC_FAULT_RESPONSE:     /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_IIN) {
+            pmdev->pages[index].iin_oc_fault_response = pmbus_receive8(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_IIN_OC_WARN_LIMIT:         /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_IIN) {
+            pmdev->pages[index].iin_oc_warn_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_POUT_OP_FAULT_LIMIT:       /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmdev->pages[index].pout_op_fault_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_POUT_OP_FAULT_RESPONSE:    /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmdev->pages[index].pout_op_fault_response = pmbus_receive8(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_POUT_OP_WARN_LIMIT:        /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmdev->pages[index].pout_op_warn_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_PIN_OP_WARN_LIMIT:         /* R/W word */
+        if (pmdev->pages[index].page_flags & PB_HAS_PIN) {
+            pmdev->pages[index].pin_op_warn_limit = pmbus_receive16(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_STATUS_BYTE:               /* R/W byte */
+        pmdev->pages[index].status_word = pmbus_receive8(pmdev);
+        break;
+
+    case PMBUS_STATUS_WORD:               /* R/W word */
+        pmdev->pages[index].status_word = pmbus_receive16(pmdev);
+        break;
+
+    case PMBUS_STATUS_VOUT:               /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_VOUT) {
+            pmdev->pages[index].status_vout = pmbus_receive8(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_STATUS_IOUT:               /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_IOUT) {
+            pmdev->pages[index].status_iout = pmbus_receive8(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_STATUS_INPUT:              /* R/W byte */
+        pmdev->pages[index].status_input = pmbus_receive8(pmdev);
+        break;
+
+    case PMBUS_STATUS_TEMPERATURE:        /* R/W byte */
+        if (pmdev->pages[index].page_flags & PB_HAS_TEMPERATURE) {
+            pmdev->pages[index].status_temperature = pmbus_receive8(pmdev);
+        } else {
+            goto passthrough;
+        }
+        break;
+
+    case PMBUS_STATUS_CML:                /* R/W byte */
+        pmdev->pages[index].status_cml = pmbus_receive8(pmdev);
+        break;
+
+    case PMBUS_STATUS_OTHER:              /* R/W byte */
+        pmdev->pages[index].status_other = pmbus_receive8(pmdev);
+        break;
+
+    case PMBUS_PAGE_PLUS_READ:            /* Block Read-only */
+    case PMBUS_CAPABILITY:                /* Read-Only byte */
+    case PMBUS_COEFFICIENTS:              /* Read-only block 5 bytes */
+    case PMBUS_READ_EIN:                  /* Read-Only block 5 bytes */
+    case PMBUS_READ_EOUT:                 /* Read-Only block 5 bytes */
+    case PMBUS_READ_VIN:                  /* Read-Only word */
+    case PMBUS_READ_IIN:                  /* Read-Only word */
+    case PMBUS_READ_VCAP:                 /* Read-Only word */
+    case PMBUS_READ_VOUT:                 /* Read-Only word */
+    case PMBUS_READ_IOUT:                 /* Read-Only word */
+    case PMBUS_READ_TEMPERATURE_1:        /* Read-Only word */
+    case PMBUS_READ_TEMPERATURE_2:        /* Read-Only word */
+    case PMBUS_READ_TEMPERATURE_3:        /* Read-Only word */
+    case PMBUS_READ_FAN_SPEED_1:          /* Read-Only word */
+    case PMBUS_READ_FAN_SPEED_2:          /* Read-Only word */
+    case PMBUS_READ_FAN_SPEED_3:          /* Read-Only word */
+    case PMBUS_READ_FAN_SPEED_4:          /* Read-Only word */
+    case PMBUS_READ_DUTY_CYCLE:           /* Read-Only word */
+    case PMBUS_READ_FREQUENCY:            /* Read-Only word */
+    case PMBUS_READ_POUT:                 /* Read-Only word */
+    case PMBUS_READ_PIN:                  /* Read-Only word */
+    case PMBUS_REVISION:                  /* Read-Only byte */
+    case PMBUS_APP_PROFILE_SUPPORT:       /* Read-Only block-read */
+    case PMBUS_MFR_VIN_MIN:               /* Read-Only word */
+    case PMBUS_MFR_VIN_MAX:               /* Read-Only word */
+    case PMBUS_MFR_IIN_MAX:               /* Read-Only word */
+    case PMBUS_MFR_PIN_MAX:               /* Read-Only word */
+    case PMBUS_MFR_VOUT_MIN:              /* Read-Only word */
+    case PMBUS_MFR_VOUT_MAX:              /* Read-Only word */
+    case PMBUS_MFR_IOUT_MAX:              /* Read-Only word */
+    case PMBUS_MFR_POUT_MAX:              /* Read-Only word */
+    case PMBUS_MFR_TAMBIENT_MAX:          /* Read-Only word */
+    case PMBUS_MFR_TAMBIENT_MIN:          /* Read-Only word */
+    case PMBUS_MFR_EFFICIENCY_LL:         /* Read-Only block 14 bytes */
+    case PMBUS_MFR_EFFICIENCY_HL:         /* Read-Only block 14 bytes */
+    case PMBUS_MFR_PIN_ACCURACY:          /* Read-Only byte */
+    case PMBUS_IC_DEVICE_ID:              /* Read-Only block-read */
+    case PMBUS_IC_DEVICE_REV:             /* Read-Only block-read */
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: writing to read-only register 0x%02x\n",
+                      __func__, pmdev->code);
+        break;
+
+passthrough:
+    /* Unimplimented registers get passed to the device */
+    default:
+        if (pmdc->write_data) {
+            ret = pmdc->write_data(pmdev, buf, len);
+        }
+        break;
+    }
+    pmbus_check_limits(pmdev);
+    pmdev->in_buf_len = 0;
+    return ret;
+}
+
+int pmbus_page_config(PMBusDevice *pmdev, uint8_t index, uint64_t flags)
+{
+    if (!pmdev->pages) { /* allocate memory for pages on first use */
+        pmbus_pages_alloc(pmdev);
+    }
+
+    /* The 0xFF page is special for commands applying to all pages */
+    if (index == PB_ALL_PAGES) {
+        for (int i = 0; i < pmdev->num_pages; i++) {
+            pmdev->pages[i].page_flags = flags;
+        }
+        return 0;
+    }
+
+    if (index > pmdev->num_pages - 1) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: index %u is out of range\n",
+                      __func__, index);
+        return -1;
+    }
+
+    pmdev->pages[index].page_flags = flags;
+
+    return 0;
+}
+
+/* TODO: include pmbus page info in vmstate */
+const VMStateDescription vmstate_pmbus_device = {
+    .name = TYPE_PMBUS_DEVICE,
+    .version_id = 0,
+    .minimum_version_id = 0,
+    .fields = (VMStateField[]) {
+        VMSTATE_SMBUS_DEVICE(smb, PMBusDevice),
+        VMSTATE_UINT8(num_pages, PMBusDevice),
+        VMSTATE_UINT8(code, PMBusDevice),
+        VMSTATE_UINT8(page, PMBusDevice),
+        VMSTATE_UINT8(capability, PMBusDevice),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void pmbus_device_finalize(Object *obj)
+{
+    PMBusDevice *pmdev = PMBUS_DEVICE(obj);
+    g_free(pmdev->pages);
+}
+
+static void pmbus_device_class_init(ObjectClass *klass, void *data)
+{
+    SMBusDeviceClass *k = SMBUS_DEVICE_CLASS(klass);
+
+    k->quick_cmd = pmbus_quick_cmd;
+    k->write_data = pmbus_write_data;
+    k->receive_byte = pmbus_receive_byte;
+}
+
+static const TypeInfo pmbus_device_type_info = {
+    .name = TYPE_PMBUS_DEVICE,
+    .parent = TYPE_SMBUS_DEVICE,
+    .instance_size = sizeof(PMBusDevice),
+    .instance_finalize = pmbus_device_finalize,
+    .abstract = true,
+    .class_size = sizeof(PMBusDeviceClass),
+    .class_init = pmbus_device_class_init,
+};
+
+static void pmbus_device_register_types(void)
+{
+    type_register_static(&pmbus_device_type_info);
+}
+
+type_init(pmbus_device_register_types)