diff --git a/Makefile.objs b/Makefile.objs
index 391e524..4546477 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -195,6 +195,7 @@ hw-obj-$(CONFIG_VIRTIO_PCI) += virtio-pci.o
 hw-obj-y += fw_cfg.o
 hw-obj-$(CONFIG_PCI) += pci.o pci_bridge.o
 hw-obj-$(CONFIG_PCI) += msix.o msi.o
+hw-obj-$(CONFIG_PCI) += shpc.o
 hw-obj-$(CONFIG_PCI) += pci_host.o pcie_host.o
 hw-obj-$(CONFIG_PCI) += ioh3420.o xio3130_upstream.o xio3130_downstream.o
 hw-obj-y += watchdog.o
diff --git a/hw/pci.h b/hw/pci.h
index 2a29654..05a7ebb 100644
--- a/hw/pci.h
+++ b/hw/pci.h
@@ -125,6 +125,9 @@ enum {
     /* command register SERR bit enabled */
 #define QEMU_PCI_CAP_SERR_BITNR 4
     QEMU_PCI_CAP_SERR = (1 << QEMU_PCI_CAP_SERR_BITNR),
+    /* Standard hot plug controller. */
+#define QEMU_PCI_SHPC_BITNR 5
+    QEMU_PCI_CAP_SHPC = (1 << QEMU_PCI_SHPC_BITNR),
 };
 
 #define TYPE_PCI_DEVICE "pci-device"
@@ -229,6 +232,9 @@ struct PCIDevice {
     /* PCI Express */
     PCIExpressDevice exp;
 
+    /* SHPC */
+    SHPCDevice *shpc;
+
     /* Location of option rom */
     char *romfile;
     bool has_rom;
diff --git a/hw/shpc.c b/hw/shpc.c
new file mode 100644
index 0000000..d731096
--- /dev/null
+++ b/hw/shpc.c
@@ -0,0 +1,673 @@
+#include <strings.h>
+#include <stdint.h>
+#include "range.h"
+#include "shpc.h"
+#include "pci.h"
+#include "pci_internals.h"
+
+/* TODO: model power only and disabled slot states. */
+/* TODO: handle SERR and wakeups */
+/* TODO: consider enabling 66MHz support */
+
+/* TODO: remove fully only on state DISABLED and LED off.
+ * track state to properly record this. */
+
+/* SHPC Working Register Set */
+#define SHPC_BASE_OFFSET  0x00 /* 4 bytes */
+#define SHPC_SLOTS_33     0x04 /* 4 bytes. Also encodes PCI-X slots. */
+#define SHPC_SLOTS_66     0x08 /* 4 bytes. */
+#define SHPC_NSLOTS       0x0C /* 1 byte */
+#define SHPC_FIRST_DEV    0x0D /* 1 byte */
+#define SHPC_PHYS_SLOT    0x0E /* 2 byte */
+#define SHPC_PHYS_NUM_MAX 0x7ff
+#define SHPC_PHYS_NUM_UP  0x2000
+#define SHPC_PHYS_MRL     0x4000
+#define SHPC_PHYS_BUTTON  0x8000
+#define SHPC_SEC_BUS      0x10 /* 2 bytes */
+#define SHPC_SEC_BUS_33   0x0
+#define SHPC_SEC_BUS_66   0x1 /* Unused */
+#define SHPC_SEC_BUS_MASK 0x7
+#define SHPC_MSI_CTL      0x12 /* 1 byte */
+#define SHPC_PROG_IFC     0x13 /* 1 byte */
+#define SHPC_PROG_IFC_1_0 0x1
+#define SHPC_CMD_CODE     0x14 /* 1 byte */
+#define SHPC_CMD_TRGT     0x15 /* 1 byte */
+#define SHPC_CMD_TRGT_MIN 0x1
+#define SHPC_CMD_TRGT_MAX 0x1f
+#define SHPC_CMD_STATUS   0x16 /* 2 bytes */
+#define SHPC_CMD_STATUS_BUSY          0x1
+#define SHPC_CMD_STATUS_MRL_OPEN      0x2
+#define SHPC_CMD_STATUS_INVALID_CMD   0x4
+#define SHPC_CMD_STATUS_INVALID_MODE  0x8
+#define SHPC_INT_LOCATOR  0x18 /* 4 bytes */
+#define SHPC_INT_COMMAND  0x1
+#define SHPC_SERR_LOCATOR 0x1C /* 4 bytes */
+#define SHPC_SERR_INT     0x20 /* 4 bytes */
+#define SHPC_INT_DIS      0x1
+#define SHPC_SERR_DIS     0x2
+#define SHPC_CMD_INT_DIS  0x4
+#define SHPC_ARB_SERR_DIS 0x8
+#define SHPC_CMD_DETECTED 0x10000
+#define SHPC_ARB_DETECTED 0x20000
+ /* 4 bytes * slot # (start from 0) */
+#define SHPC_SLOT_REG(s)         (0x24 + (s) * 4)
+ /* 2 bytes */
+#define SHPC_SLOT_STATUS(s)       (0x0 + SHPC_SLOT_REG(s))
+
+/* Same slot state masks are used for command and status registers */
+#define SHPC_SLOT_STATE_MASK     0x03
+#define SHPC_SLOT_STATE_SHIFT \
+    (ffs(SHPC_SLOT_STATE_MASK) - 1)
+
+#define SHPC_STATE_NO       0x0
+#define SHPC_STATE_PWRONLY  0x1
+#define SHPC_STATE_ENABLED  0x2
+#define SHPC_STATE_DISABLED 0x3
+
+#define SHPC_SLOT_PWR_LED_MASK   0xC
+#define SHPC_SLOT_PWR_LED_SHIFT \
+    (ffs(SHPC_SLOT_PWR_LED_MASK) - 1)
+#define SHPC_SLOT_ATTN_LED_MASK  0x30
+#define SHPC_SLOT_ATTN_LED_SHIFT \
+    (ffs(SHPC_SLOT_ATTN_LED_MASK) - 1)
+
+#define SHPC_LED_NO     0x0
+#define SHPC_LED_ON     0x1
+#define SHPC_LED_BLINK  0x2
+#define SHPC_LED_OFF    0x3
+
+#define SHPC_SLOT_STATUS_PWR_FAULT      0x40
+#define SHPC_SLOT_STATUS_BUTTON         0x80
+#define SHPC_SLOT_STATUS_MRL_OPEN       0x100
+#define SHPC_SLOT_STATUS_66             0x200
+#define SHPC_SLOT_STATUS_PRSNT_MASK     0xC00
+#define SHPC_SLOT_STATUS_PRSNT_EMPTY    0x3
+#define SHPC_SLOT_STATUS_PRSNT_25W      0x1
+#define SHPC_SLOT_STATUS_PRSNT_15W      0x2
+#define SHPC_SLOT_STATUS_PRSNT_7_5W     0x0
+
+#define SHPC_SLOT_STATUS_PRSNT_PCIX     0x3000
+
+
+ /* 1 byte */
+#define SHPC_SLOT_EVENT_LATCH(s)        (0x2 + SHPC_SLOT_REG(s))
+ /* 1 byte */
+#define SHPC_SLOT_EVENT_SERR_INT_DIS(d, s) (0x3 + SHPC_SLOT_REG(s))
+#define SHPC_SLOT_EVENT_PRESENCE        0x01
+#define SHPC_SLOT_EVENT_ISOLATED_FAULT  0x02
+#define SHPC_SLOT_EVENT_BUTTON          0x04
+#define SHPC_SLOT_EVENT_MRL             0x08
+#define SHPC_SLOT_EVENT_CONNECTED_FAULT 0x10
+/* Bits below are used for Serr/Int disable only */
+#define SHPC_SLOT_EVENT_MRL_SERR_DIS    0x20
+#define SHPC_SLOT_EVENT_CONNECTED_FAULT_SERR_DIS 0x40
+
+#define SHPC_MIN_SLOTS        1
+#define SHPC_MAX_SLOTS        31
+#define SHPC_SIZEOF(d)    SHPC_SLOT_REG((d)->shpc->nslots)
+
+/* SHPC Slot identifiers */
+
+/* Hotplug supported at 31 slots out of the total 32.  We reserve slot 0,
+   and give the rest of them physical *and* pci numbers starting from 1, so
+   they match logical numbers.  Note: this means that multiple slots must have
+   different chassis number values, to make chassis+physical slot unique.
+   TODO: make this configurable? */
+#define SHPC_IDX_TO_LOGICAL(slot) ((slot) + 1)
+#define SHPC_LOGICAL_TO_IDX(target) ((target) - 1)
+#define SHPC_IDX_TO_PCI(slot) ((slot) + 1)
+#define SHPC_PCI_TO_IDX(pci_slot) ((pci_slot) - 1)
+#define SHPC_IDX_TO_PHYSICAL(slot) ((slot) + 1)
+
+static int roundup_pow_of_two(int x)
+{
+    x |= (x >> 1);
+    x |= (x >> 2);
+    x |= (x >> 4);
+    x |= (x >> 8);
+    x |= (x >> 16);
+    return x + 1;
+}
+
+static uint16_t shpc_get_status(SHPCDevice *shpc, int slot, uint16_t msk)
+{
+    uint8_t *status = shpc->config + SHPC_SLOT_STATUS(slot);
+    return (pci_get_word(status) & msk) >> (ffs(msk) - 1);
+}
+
+static void shpc_set_status(SHPCDevice *shpc,
+                            int slot, uint8_t value, uint16_t msk)
+{
+    uint8_t *status = shpc->config + SHPC_SLOT_STATUS(slot);
+    pci_word_test_and_clear_mask(status, msk);
+    pci_word_test_and_set_mask(status, value << (ffs(msk) - 1));
+}
+
+static void shpc_interrupt_update(PCIDevice *d)
+{
+    SHPCDevice *shpc = d->shpc;
+    int slot;
+    int level = 0;
+    uint32_t serr_int;
+    uint32_t int_locator = 0;
+
+    /* Update interrupt locator register */
+    for (slot = 0; slot < shpc->nslots; ++slot) {
+        uint8_t event = shpc->config[SHPC_SLOT_EVENT_LATCH(slot)];
+        uint8_t disable = shpc->config[SHPC_SLOT_EVENT_SERR_INT_DIS(d, slot)];
+        uint32_t mask = 1 << SHPC_IDX_TO_LOGICAL(slot);
+        if (event & ~disable) {
+            int_locator |= mask;
+        }
+    }
+    serr_int = pci_get_long(shpc->config + SHPC_SERR_INT);
+    if ((serr_int & SHPC_CMD_DETECTED) && !(serr_int & SHPC_CMD_INT_DIS)) {
+        int_locator |= SHPC_INT_COMMAND;
+    }
+    pci_set_long(shpc->config + SHPC_INT_LOCATOR, int_locator);
+    level = (!(serr_int & SHPC_INT_DIS) && int_locator) ? 1 : 0;
+    qemu_set_irq(d->irq[0], level);
+}
+
+static void shpc_set_sec_bus_speed(SHPCDevice *shpc, uint8_t speed)
+{
+    switch (speed) {
+    case SHPC_SEC_BUS_33:
+        shpc->config[SHPC_SEC_BUS] &= ~SHPC_SEC_BUS_MASK;
+        shpc->config[SHPC_SEC_BUS] |= speed;
+        break;
+    default:
+        pci_word_test_and_set_mask(shpc->config + SHPC_CMD_STATUS,
+                                   SHPC_CMD_STATUS_INVALID_MODE);
+    }
+}
+
+void shpc_reset(PCIDevice *d)
+{
+    SHPCDevice *shpc = d->shpc;
+    int nslots = shpc->nslots;
+    int i;
+    memset(shpc->config, 0, SHPC_SIZEOF(d));
+    pci_set_byte(shpc->config + SHPC_NSLOTS, nslots);
+    pci_set_long(shpc->config + SHPC_SLOTS_33, nslots);
+    pci_set_long(shpc->config + SHPC_SLOTS_66, 0);
+    pci_set_byte(shpc->config + SHPC_FIRST_DEV, SHPC_IDX_TO_PCI(0));
+    pci_set_word(shpc->config + SHPC_PHYS_SLOT,
+                 SHPC_IDX_TO_PHYSICAL(0) |
+                 SHPC_PHYS_NUM_UP |
+                 SHPC_PHYS_MRL |
+                 SHPC_PHYS_BUTTON);
+    pci_set_long(shpc->config + SHPC_SERR_INT, SHPC_INT_DIS |
+                 SHPC_SERR_DIS |
+                 SHPC_CMD_INT_DIS |
+                 SHPC_ARB_SERR_DIS);
+    pci_set_byte(shpc->config + SHPC_PROG_IFC, SHPC_PROG_IFC_1_0);
+    pci_set_word(shpc->config + SHPC_SEC_BUS, SHPC_SEC_BUS_33);
+    for (i = 0; i < shpc->nslots; ++i) {
+        pci_set_word(shpc->config + SHPC_SLOT_EVENT_SERR_INT_DIS(d, i),
+                     SHPC_SLOT_EVENT_PRESENCE |
+                     SHPC_SLOT_EVENT_ISOLATED_FAULT |
+                     SHPC_SLOT_EVENT_BUTTON |
+                     SHPC_SLOT_EVENT_MRL |
+                     SHPC_SLOT_EVENT_CONNECTED_FAULT |
+                     SHPC_SLOT_EVENT_MRL_SERR_DIS |
+                     SHPC_SLOT_EVENT_CONNECTED_FAULT_SERR_DIS);
+        if (shpc->sec_bus->devices[PCI_DEVFN(SHPC_IDX_TO_PCI(i), 0)]) {
+            shpc_set_status(shpc, i, SHPC_STATE_ENABLED, SHPC_SLOT_STATE_MASK);
+            shpc_set_status(shpc, i, 0, SHPC_SLOT_STATUS_MRL_OPEN);
+            shpc_set_status(shpc, i, SHPC_SLOT_STATUS_PRSNT_7_5W,
+                            SHPC_SLOT_STATUS_PRSNT_MASK);
+            shpc_set_status(shpc, i, SHPC_LED_ON, SHPC_SLOT_PWR_LED_MASK);
+        } else {
+            shpc_set_status(shpc, i, SHPC_STATE_DISABLED, SHPC_SLOT_STATE_MASK);
+            shpc_set_status(shpc, i, 1, SHPC_SLOT_STATUS_MRL_OPEN);
+            shpc_set_status(shpc, i, SHPC_SLOT_STATUS_PRSNT_EMPTY,
+                            SHPC_SLOT_STATUS_PRSNT_MASK);
+            shpc_set_status(shpc, i, SHPC_LED_OFF, SHPC_SLOT_PWR_LED_MASK);
+        }
+        shpc_set_status(shpc, i, 0, SHPC_SLOT_STATUS_66);
+    }
+    shpc_set_sec_bus_speed(shpc, SHPC_SEC_BUS_33);
+    shpc_interrupt_update(d);
+}
+
+static void shpc_invalid_command(SHPCDevice *shpc)
+{
+    pci_word_test_and_set_mask(shpc->config + SHPC_CMD_STATUS,
+                               SHPC_CMD_STATUS_INVALID_CMD);
+}
+
+static void shpc_free_devices_in_slot(SHPCDevice *shpc, int slot)
+{
+    int devfn;
+    int pci_slot = SHPC_IDX_TO_PCI(slot);
+    for (devfn = PCI_DEVFN(pci_slot, 0);
+         devfn <= PCI_DEVFN(pci_slot, PCI_FUNC_MAX - 1);
+         ++devfn) {
+        PCIDevice *affected_dev = shpc->sec_bus->devices[devfn];
+        if (affected_dev) {
+            qdev_free(&affected_dev->qdev);
+        }
+    }
+}
+
+static void shpc_slot_command(SHPCDevice *shpc, uint8_t target,
+                              uint8_t state, uint8_t power, uint8_t attn)
+{
+    uint8_t current_state;
+    int slot = SHPC_LOGICAL_TO_IDX(target);
+    if (target < SHPC_CMD_TRGT_MIN || slot >= shpc->nslots) {
+        shpc_invalid_command(shpc);
+        return;
+    }
+    current_state = shpc_get_status(shpc, slot, SHPC_SLOT_STATE_MASK);
+    if (current_state == SHPC_STATE_ENABLED && state == SHPC_STATE_PWRONLY) {
+        shpc_invalid_command(shpc);
+        return;
+    }
+
+    switch (power) {
+    case SHPC_LED_NO:
+        break;
+    default:
+        /* TODO: send event to monitor */
+        shpc_set_status(shpc, slot, power, SHPC_SLOT_PWR_LED_MASK);
+    }
+    switch (attn) {
+    case SHPC_LED_NO:
+        break;
+    default:
+        /* TODO: send event to monitor */
+        shpc_set_status(shpc, slot, attn, SHPC_SLOT_ATTN_LED_MASK);
+    }
+
+    if ((current_state == SHPC_STATE_DISABLED && state == SHPC_STATE_PWRONLY) ||
+        (current_state == SHPC_STATE_DISABLED && state == SHPC_STATE_ENABLED)) {
+        shpc_set_status(shpc, slot, state, SHPC_SLOT_STATE_MASK);
+    } else if ((current_state == SHPC_STATE_ENABLED ||
+                current_state == SHPC_STATE_PWRONLY) &&
+               state == SHPC_STATE_DISABLED) {
+        shpc_set_status(shpc, slot, state, SHPC_SLOT_STATE_MASK);
+        power = shpc_get_status(shpc, slot, SHPC_SLOT_PWR_LED_MASK);
+        /* TODO: track what monitor requested. */
+        /* Look at LED to figure out whether it's ok to remove the device. */
+        if (power == SHPC_LED_OFF) {
+            shpc_free_devices_in_slot(shpc, slot);
+            shpc_set_status(shpc, slot, 1, SHPC_SLOT_STATUS_MRL_OPEN);
+            shpc_set_status(shpc, slot, SHPC_SLOT_STATUS_PRSNT_EMPTY,
+                            SHPC_SLOT_STATUS_PRSNT_MASK);
+            shpc->config[SHPC_SLOT_EVENT_LATCH(slot)] |=
+                SHPC_SLOT_EVENT_BUTTON |
+                SHPC_SLOT_EVENT_MRL |
+                SHPC_SLOT_EVENT_PRESENCE;
+        }
+    }
+}
+
+static void shpc_command(SHPCDevice *shpc)
+{
+    uint8_t code = pci_get_byte(shpc->config + SHPC_CMD_CODE);
+    uint8_t speed;
+    uint8_t target;
+    uint8_t attn;
+    uint8_t power;
+    uint8_t state;
+    int i;
+
+    /* Clear status from the previous command. */
+    pci_word_test_and_clear_mask(shpc->config + SHPC_CMD_STATUS,
+                                 SHPC_CMD_STATUS_BUSY |
+                                 SHPC_CMD_STATUS_MRL_OPEN |
+                                 SHPC_CMD_STATUS_INVALID_CMD |
+                                 SHPC_CMD_STATUS_INVALID_MODE);
+    switch (code) {
+    case 0x00 ... 0x3f:
+        target = shpc->config[SHPC_CMD_TRGT] & SHPC_CMD_TRGT_MAX;
+        state = (code & SHPC_SLOT_STATE_MASK) >> SHPC_SLOT_STATE_SHIFT;
+        power = (code & SHPC_SLOT_PWR_LED_MASK) >> SHPC_SLOT_PWR_LED_SHIFT;
+        attn = (code & SHPC_SLOT_ATTN_LED_MASK) >> SHPC_SLOT_ATTN_LED_SHIFT;
+        shpc_slot_command(shpc, target, state, power, attn);
+        break;
+    case 0x40 ... 0x47:
+        speed = code & SHPC_SEC_BUS_MASK;
+        shpc_set_sec_bus_speed(shpc, speed);
+        break;
+    case 0x48:
+        /* Power only all slots */
+        /* first verify no slots are enabled */
+        for (i = 0; i < shpc->nslots; ++i) {
+            state = shpc_get_status(shpc, i, SHPC_SLOT_STATE_MASK);
+            if (state == SHPC_STATE_ENABLED) {
+                shpc_invalid_command(shpc);
+                goto done;
+            }
+        }
+        for (i = 0; i < shpc->nslots; ++i) {
+            if (!(shpc_get_status(shpc, i, SHPC_SLOT_STATUS_MRL_OPEN))) {
+                shpc_slot_command(shpc, i + SHPC_CMD_TRGT_MIN,
+                                  SHPC_STATE_PWRONLY, SHPC_LED_ON, SHPC_LED_NO);
+            } else {
+                shpc_slot_command(shpc, i + SHPC_CMD_TRGT_MIN,
+                                  SHPC_STATE_NO, SHPC_LED_OFF, SHPC_LED_NO);
+            }
+        }
+        break;
+    case 0x49:
+        /* Enable all slots */
+        /* TODO: Spec says this shall fail if some are already enabled.
+         * This doesn't make sense - why not? a spec bug? */
+        for (i = 0; i < shpc->nslots; ++i) {
+            state = shpc_get_status(shpc, i, SHPC_SLOT_STATE_MASK);
+            if (state == SHPC_STATE_ENABLED) {
+                shpc_invalid_command(shpc);
+                goto done;
+            }
+        }
+        for (i = 0; i < shpc->nslots; ++i) {
+            if (!(shpc_get_status(shpc, i, SHPC_SLOT_STATUS_MRL_OPEN))) {
+                shpc_slot_command(shpc, i + SHPC_CMD_TRGT_MIN,
+                                  SHPC_STATE_ENABLED, SHPC_LED_ON, SHPC_LED_NO);
+            } else {
+                shpc_slot_command(shpc, i + SHPC_CMD_TRGT_MIN,
+                                  SHPC_STATE_NO, SHPC_LED_OFF, SHPC_LED_NO);
+            }
+        }
+        break;
+    default:
+        shpc_invalid_command(shpc);
+        break;
+    }
+done:
+    pci_long_test_and_set_mask(shpc->config + SHPC_SERR_INT, SHPC_CMD_DETECTED);
+}
+
+static void shpc_write(PCIDevice *d, unsigned addr, uint64_t val, int l)
+{
+    SHPCDevice *shpc = d->shpc;
+    int i;
+    if (addr >= SHPC_SIZEOF(d)) {
+        return;
+    }
+    l = MIN(l, SHPC_SIZEOF(d) - addr);
+
+    /* TODO: code duplicated from pci.c */
+    for (i = 0; i < l; val >>= 8, ++i) {
+        unsigned a = addr + i;
+        uint8_t wmask = shpc->wmask[a];
+        uint8_t w1cmask = shpc->w1cmask[a];
+        assert(!(wmask & w1cmask));
+        shpc->config[a] = (shpc->config[a] & ~wmask) | (val & wmask);
+        shpc->config[a] &= ~(val & w1cmask); /* W1C: Write 1 to Clear */
+    }
+    if (ranges_overlap(addr, l, SHPC_CMD_CODE, 2)) {
+        shpc_command(shpc);
+    }
+    shpc_interrupt_update(d);
+}
+
+static uint64_t shpc_read(PCIDevice *d, unsigned addr, int l)
+{
+    uint64_t val = 0x0;
+    if (addr >= SHPC_SIZEOF(d)) {
+        return val;
+    }
+    l = MIN(l, SHPC_SIZEOF(d) - addr);
+    memcpy(&val, d->shpc->config + addr, l);
+    return val;
+}
+
+/* SHPC Bridge Capability */
+#define SHPC_CAP_LENGTH 0x08
+#define SHPC_CAP_DWORD_SELECT 0x2 /* 1 byte */
+#define SHPC_CAP_CxP 0x3 /* 1 byte: CSP, CIP */
+#define SHPC_CAP_DWORD_DATA 0x4 /* 4 bytes */
+#define SHPC_CAP_CSP_MASK 0x4
+#define SHPC_CAP_CIP_MASK 0x8
+
+static uint8_t shpc_cap_dword(PCIDevice *d)
+{
+    return pci_get_byte(d->config + d->shpc->cap + SHPC_CAP_DWORD_SELECT);
+}
+
+/* Update dword data capability register */
+static void shpc_cap_update_dword(PCIDevice *d)
+{
+    unsigned data;
+    data = shpc_read(d, shpc_cap_dword(d) * 4, 4);
+    pci_set_long(d->config  + d->shpc->cap + SHPC_CAP_DWORD_DATA, data);
+}
+
+/* Add SHPC capability to the config space for the device. */
+static int shpc_cap_add_config(PCIDevice *d)
+{
+    uint8_t *config;
+    int config_offset;
+    config_offset = pci_add_capability(d, PCI_CAP_ID_SHPC,
+                                       0, SHPC_CAP_LENGTH);
+    if (config_offset < 0) {
+        return config_offset;
+    }
+    config = d->config + config_offset;
+
+    pci_set_byte(config + SHPC_CAP_DWORD_SELECT, 0);
+    pci_set_byte(config + SHPC_CAP_CxP, 0);
+    pci_set_long(config + SHPC_CAP_DWORD_DATA, 0);
+    d->shpc->cap = config_offset;
+    /* Make dword select and data writeable. */
+    pci_set_byte(d->wmask + config_offset + SHPC_CAP_DWORD_SELECT, 0xff);
+    pci_set_long(d->wmask + config_offset + SHPC_CAP_DWORD_DATA, 0xffffffff);
+    return 0;
+}
+
+static uint64_t shpc_mmio_read(void *opaque, target_phys_addr_t addr,
+                               unsigned size)
+{
+    return shpc_read(opaque, addr, size);
+}
+
+static void shpc_mmio_write(void *opaque, target_phys_addr_t addr,
+                            uint64_t val, unsigned size)
+{
+    shpc_write(opaque, addr, val, size);
+}
+
+static const MemoryRegionOps shpc_mmio_ops = {
+    .read = shpc_mmio_read,
+    .write = shpc_mmio_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+    .valid = {
+        /* SHPC ECN requires dword accesses, but the original 1.0 spec doesn't.
+         * It's easier to suppport all sizes than worry about it. */
+        .min_access_size = 1,
+        .max_access_size = 4,
+    },
+};
+
+static int shpc_device_hotplug(DeviceState *qdev, PCIDevice *affected_dev,
+                               PCIHotplugState hotplug_state)
+{
+    int pci_slot = PCI_SLOT(affected_dev->devfn);
+    uint8_t state;
+    uint8_t led;
+    PCIDevice *d = DO_UPCAST(PCIDevice, qdev, qdev);
+    SHPCDevice *shpc = d->shpc;
+    int slot = SHPC_PCI_TO_IDX(pci_slot);
+    if (pci_slot < SHPC_IDX_TO_PCI(0) || slot >= shpc->nslots) {
+        error_report("Unsupported PCI slot %d for standard hotplug "
+                     "controller. Valid slots are between %d and %d.",
+                     pci_slot, SHPC_IDX_TO_PCI(0),
+                     SHPC_IDX_TO_PCI(shpc->nslots) - 1);
+        return -1;
+    }
+    /* Don't send event when device is enabled during qemu machine creation:
+     * it is present on boot, no hotplug event is necessary. We do send an
+     * event when the device is disabled later. */
+    if (hotplug_state == PCI_COLDPLUG_ENABLED) {
+        shpc_set_status(shpc, slot, 0, SHPC_SLOT_STATUS_MRL_OPEN);
+        shpc_set_status(shpc, slot, SHPC_SLOT_STATUS_PRSNT_7_5W,
+                        SHPC_SLOT_STATUS_PRSNT_MASK);
+        return 0;
+    }
+    if (hotplug_state == PCI_HOTPLUG_DISABLED) {
+        shpc->config[SHPC_SLOT_EVENT_LATCH(slot)] |= SHPC_SLOT_EVENT_BUTTON;
+        state = shpc_get_status(shpc, slot, SHPC_SLOT_STATE_MASK);
+        led = shpc_get_status(shpc, slot, SHPC_SLOT_PWR_LED_MASK);
+        if (state == SHPC_STATE_DISABLED && led == SHPC_LED_OFF) {
+            shpc_free_devices_in_slot(shpc, slot);
+            shpc_set_status(shpc, slot, 1, SHPC_SLOT_STATUS_MRL_OPEN);
+            shpc_set_status(shpc, slot, SHPC_SLOT_STATUS_PRSNT_EMPTY,
+                            SHPC_SLOT_STATUS_PRSNT_MASK);
+            shpc->config[SHPC_SLOT_EVENT_LATCH(slot)] |=
+                SHPC_SLOT_EVENT_MRL |
+                SHPC_SLOT_EVENT_PRESENCE;
+        }
+    } else {
+        /* This could be a cancellation of the previous removal.
+         * We check MRL state to figure out. */
+        if (shpc_get_status(shpc, slot, SHPC_SLOT_STATUS_MRL_OPEN)) {
+            shpc_set_status(shpc, slot, 0, SHPC_SLOT_STATUS_MRL_OPEN);
+            shpc_set_status(shpc, slot, SHPC_SLOT_STATUS_PRSNT_7_5W,
+                            SHPC_SLOT_STATUS_PRSNT_MASK);
+            shpc->config[SHPC_SLOT_EVENT_LATCH(slot)] |=
+                SHPC_SLOT_EVENT_BUTTON |
+                SHPC_SLOT_EVENT_MRL |
+                SHPC_SLOT_EVENT_PRESENCE;
+        } else {
+            /* Press attention button to cancel removal */
+            shpc->config[SHPC_SLOT_EVENT_LATCH(slot)] |=
+                SHPC_SLOT_EVENT_BUTTON;
+        }
+    }
+    shpc_set_status(shpc, slot, 0, SHPC_SLOT_STATUS_66);
+    shpc_interrupt_update(d);
+    return 0;
+}
+
+/* Initialize the SHPC structure in bridge's BAR. */
+int shpc_init(PCIDevice *d, PCIBus *sec_bus, MemoryRegion *bar, unsigned offset)
+{
+    int i, ret;
+    int nslots = SHPC_MAX_SLOTS; /* TODO: qdev property? */
+    SHPCDevice *shpc = d->shpc = g_malloc0(sizeof(*d->shpc));
+    shpc->sec_bus = sec_bus;
+    ret = shpc_cap_add_config(d);
+    if (ret) {
+        g_free(d->shpc);
+        return ret;
+    }
+    if (nslots < SHPC_MIN_SLOTS) {
+        return 0;
+    }
+    if (nslots > SHPC_MAX_SLOTS ||
+        SHPC_IDX_TO_PCI(nslots) > PCI_SLOT_MAX) {
+        /* TODO: report an error mesage that makes sense. */
+        return -EINVAL;
+    }
+    shpc->nslots = nslots;
+    shpc->config = g_malloc0(SHPC_SIZEOF(d));
+    shpc->cmask = g_malloc0(SHPC_SIZEOF(d));
+    shpc->wmask = g_malloc0(SHPC_SIZEOF(d));
+    shpc->w1cmask = g_malloc0(SHPC_SIZEOF(d));
+
+    shpc_reset(d);
+
+    pci_set_long(shpc->config + SHPC_BASE_OFFSET, offset);
+
+    pci_set_byte(shpc->wmask + SHPC_CMD_CODE, 0xff);
+    pci_set_byte(shpc->wmask + SHPC_CMD_TRGT, SHPC_CMD_TRGT_MAX);
+    pci_set_byte(shpc->wmask + SHPC_CMD_TRGT, SHPC_CMD_TRGT_MAX);
+    pci_set_long(shpc->wmask + SHPC_SERR_INT,
+                 SHPC_INT_DIS |
+                 SHPC_SERR_DIS |
+                 SHPC_CMD_INT_DIS |
+                 SHPC_ARB_SERR_DIS);
+    pci_set_long(shpc->w1cmask + SHPC_SERR_INT,
+                 SHPC_CMD_DETECTED |
+                 SHPC_ARB_DETECTED);
+    for (i = 0; i < nslots; ++i) {
+        pci_set_byte(shpc->wmask +
+                     SHPC_SLOT_EVENT_SERR_INT_DIS(d, i),
+                     SHPC_SLOT_EVENT_PRESENCE |
+                     SHPC_SLOT_EVENT_ISOLATED_FAULT |
+                     SHPC_SLOT_EVENT_BUTTON |
+                     SHPC_SLOT_EVENT_MRL |
+                     SHPC_SLOT_EVENT_CONNECTED_FAULT |
+                     SHPC_SLOT_EVENT_MRL_SERR_DIS |
+                     SHPC_SLOT_EVENT_CONNECTED_FAULT_SERR_DIS);
+        pci_set_byte(shpc->w1cmask +
+                     SHPC_SLOT_EVENT_LATCH(i),
+                     SHPC_SLOT_EVENT_PRESENCE |
+                     SHPC_SLOT_EVENT_ISOLATED_FAULT |
+                     SHPC_SLOT_EVENT_BUTTON |
+                     SHPC_SLOT_EVENT_MRL |
+                     SHPC_SLOT_EVENT_CONNECTED_FAULT);
+    }
+
+    /* TODO: init cmask */
+    memory_region_init_io(&shpc->mmio, &shpc_mmio_ops, d, "shpc-mmio",
+                          SHPC_SIZEOF(d));
+    shpc_cap_update_dword(d);
+    memory_region_add_subregion(bar, offset, &shpc->mmio);
+    pci_bus_hotplug(sec_bus, shpc_device_hotplug, &d->qdev);
+
+    d->cap_present |= QEMU_PCI_CAP_SHPC;
+    return 0;
+}
+
+int shpc_bar_size(PCIDevice *d)
+{
+    return roundup_pow_of_two(SHPC_SLOT_REG(SHPC_MAX_SLOTS));
+}
+
+void shpc_cleanup(PCIDevice *d, MemoryRegion *bar)
+{
+    SHPCDevice *shpc = d->shpc;
+    d->cap_present &= ~QEMU_PCI_CAP_SHPC;
+    memory_region_del_subregion(bar, &shpc->mmio);
+    /* TODO: cleanup config space changes? */
+    g_free(shpc->config);
+    g_free(shpc->cmask);
+    g_free(shpc->wmask);
+    g_free(shpc->w1cmask);
+    memory_region_destroy(&shpc->mmio);
+    g_free(shpc);
+}
+
+void shpc_cap_write_config(PCIDevice *d, uint32_t addr, uint32_t val, int l)
+{
+    if (!ranges_overlap(addr, l, d->shpc->cap, SHPC_CAP_LENGTH)) {
+        return;
+    }
+    fprintf(stderr, "%s: 0x%x 0x%x %d\n", __func__, addr, val, l);
+    if (ranges_overlap(addr, l, d->shpc->cap + SHPC_CAP_DWORD_DATA, 4)) {
+        unsigned dword_data;
+        dword_data = pci_get_long(d->shpc->config + d->shpc->cap
+                                  + SHPC_CAP_DWORD_DATA);
+        shpc_write(d, shpc_cap_dword(d) * 4, dword_data, 4);
+    }
+    /* Update cap dword data in case guest is going to read it. */
+    shpc_cap_update_dword(d);
+}
+
+static void shpc_save(QEMUFile *f, void *pv, size_t size)
+{
+    PCIDevice *d = container_of(pv, PCIDevice, shpc);
+    qemu_put_buffer(f, d->shpc->config, SHPC_SIZEOF(d));
+}
+
+static int shpc_load(QEMUFile *f, void *pv, size_t size)
+{
+    PCIDevice *d = container_of(pv, PCIDevice, shpc);
+    int ret = qemu_get_buffer(f, d->shpc->config, SHPC_SIZEOF(d));
+    if (ret != SHPC_SIZEOF(d)) {
+        return -EINVAL;
+    }
+    shpc_interrupt_update(d);
+    return 0;
+}
+
+VMStateInfo shpc_vmstate_info = {
+    .name = "shpc",
+    .get  = shpc_load,
+    .put  = shpc_save,
+};
diff --git a/hw/shpc.h b/hw/shpc.h
new file mode 100644
index 0000000..681eb85
--- /dev/null
+++ b/hw/shpc.h
@@ -0,0 +1,45 @@
+#ifndef SHPC_H
+#define SHPC_H
+
+#include "qemu-common.h"
+#include "memory.h"
+#include "vmstate.h"
+
+struct SHPCDevice {
+    /* Capability offset in device's config space */
+    int cap;
+
+    /* # of hot-pluggable slots */
+    int nslots;
+
+    /* SHPC WRS: working register set */
+    uint8_t *config;
+
+    /* Used to enable checks on load. Note that writable bits are
+     * never checked even if set in cmask. */
+    uint8_t *cmask;
+
+    /* Used to implement R/W bytes */
+    uint8_t *wmask;
+
+    /* Used to implement RW1C(Write 1 to Clear) bytes */
+    uint8_t *w1cmask;
+
+    /* MMIO for the SHPC BAR */
+    MemoryRegion mmio;
+
+    /* Bus controlled by this SHPC */
+    PCIBus *sec_bus;
+};
+
+void shpc_reset(PCIDevice *d);
+int shpc_bar_size(PCIDevice *dev);
+int shpc_init(PCIDevice *dev, PCIBus *sec_bus, MemoryRegion *bar, unsigned off);
+void shpc_cleanup(PCIDevice *dev, MemoryRegion *bar);
+void shpc_cap_write_config(PCIDevice *d, uint32_t addr, uint32_t val, int len);
+
+extern VMStateInfo shpc_vmstate_info;
+#define SHPC_VMSTATE(_field, _type) \
+    VMSTATE_BUFFER_UNSAFE_INFO(_field, _type, 0, shpc_vmstate_info, 0)
+
+#endif
diff --git a/qemu-common.h b/qemu-common.h
index c5e9cad..dee4db3 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -247,6 +247,7 @@ typedef struct SSIBus SSIBus;
 typedef struct EventNotifier EventNotifier;
 typedef struct VirtIODevice VirtIODevice;
 typedef struct QEMUSGList QEMUSGList;
+typedef struct SHPCDevice SHPCDevice;
 
 typedef uint64_t pcibus_t;
 
