hw/gpio: Add GPIO model for Nuvoton NPCM7xx

The NPCM7xx chips have multiple GPIO controllers that are mostly
identical except for some minor differences like the reset values of
some registers. Each controller controls up to 32 pins.

Each individual pin is modeled as a pair of unnamed GPIOs -- one for
emitting the actual pin state, and one for driving the pin externally.
Like the nRF51 GPIO controller, a gpio level may be negative, which
means the pin is not driven, or floating.

Reviewed-by: Tyrone Ting <kfting@nuvoton.com>
Signed-off-by: Havard Skinnemoen <hskinnemoen@google.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

4 files changed, 512 insertions, 0 deletions

diff --git a/hw/arm/npcm7xx.c b/hw/arm/npcm7xx.c
index c1d1225..47e2b6f 100644
--- a/hw/arm/npcm7xx.c
+++ b/hw/arm/npcm7xx.c
@@ -96,6 +96,14 @@ enum NPCM7xxInterrupt {
     NPCM7XX_WDG2_IRQ,                   /* Timer Module 2 Watchdog */
     NPCM7XX_EHCI_IRQ            = 61,
     NPCM7XX_OHCI_IRQ            = 62,
+    NPCM7XX_GPIO0_IRQ           = 116,
+    NPCM7XX_GPIO1_IRQ,
+    NPCM7XX_GPIO2_IRQ,
+    NPCM7XX_GPIO3_IRQ,
+    NPCM7XX_GPIO4_IRQ,
+    NPCM7XX_GPIO5_IRQ,
+    NPCM7XX_GPIO6_IRQ,
+    NPCM7XX_GPIO7_IRQ,
 };
 
 /* Total number of GIC interrupts, including internal Cortex-A9 interrupts. */
@@ -131,6 +139,55 @@ static const hwaddr npcm7xx_fiu3_flash_addr[] = {
 };
 
 static const struct {
+    hwaddr regs_addr;
+    uint32_t unconnected_pins;
+    uint32_t reset_pu;
+    uint32_t reset_pd;
+    uint32_t reset_osrc;
+    uint32_t reset_odsc;
+} npcm7xx_gpio[] = {
+    {
+        .regs_addr = 0xf0010000,
+        .reset_pu = 0xff03ffff,
+        .reset_pd = 0x00fc0000,
+    }, {
+        .regs_addr = 0xf0011000,
+        .unconnected_pins = 0x0000001e,
+        .reset_pu = 0xfefffe07,
+        .reset_pd = 0x010001e0,
+    }, {
+        .regs_addr = 0xf0012000,
+        .reset_pu = 0x780fffff,
+        .reset_pd = 0x07f00000,
+        .reset_odsc = 0x00700000,
+    }, {
+        .regs_addr = 0xf0013000,
+        .reset_pu = 0x00fc0000,
+        .reset_pd = 0xff000000,
+    }, {
+        .regs_addr = 0xf0014000,
+        .reset_pu = 0xffffffff,
+    }, {
+        .regs_addr = 0xf0015000,
+        .reset_pu = 0xbf83f801,
+        .reset_pd = 0x007c0000,
+        .reset_osrc = 0x000000f1,
+        .reset_odsc = 0x3f9f80f1,
+    }, {
+        .regs_addr = 0xf0016000,
+        .reset_pu = 0xfc00f801,
+        .reset_pd = 0x000007fe,
+        .reset_odsc = 0x00000800,
+    }, {
+        .regs_addr = 0xf0017000,
+        .unconnected_pins = 0xffffff00,
+        .reset_pu = 0x0000007f,
+        .reset_osrc = 0x0000007f,
+        .reset_odsc = 0x0000007f,
+    },
+};
+
+static const struct {
     const char *name;
     hwaddr regs_addr;
     int cs_count;
@@ -269,6 +326,10 @@ static void npcm7xx_init(Object *obj)
         object_initialize_child(obj, "tim[*]", &s->tim[i], TYPE_NPCM7XX_TIMER);
     }
 
+    for (i = 0; i < ARRAY_SIZE(s->gpio); i++) {
+        object_initialize_child(obj, "gpio[*]", &s->gpio[i], TYPE_NPCM7XX_GPIO);
+    }
+
     object_initialize_child(obj, "ehci", &s->ehci, TYPE_NPCM7XX_EHCI);
     object_initialize_child(obj, "ohci", &s->ohci, TYPE_SYSBUS_OHCI);
 
@@ -389,6 +450,25 @@ static void npcm7xx_realize(DeviceState *dev, Error **errp)
     sysbus_realize(SYS_BUS_DEVICE(&s->rng), &error_abort);
     sysbus_mmio_map(SYS_BUS_DEVICE(&s->rng), 0, NPCM7XX_RNG_BA);
 
+    /* GPIO modules. Cannot fail. */
+    QEMU_BUILD_BUG_ON(ARRAY_SIZE(npcm7xx_gpio) != ARRAY_SIZE(s->gpio));
+    for (i = 0; i < ARRAY_SIZE(s->gpio); i++) {
+        Object *obj = OBJECT(&s->gpio[i]);
+
+        object_property_set_uint(obj, "reset-pullup",
+                                 npcm7xx_gpio[i].reset_pu, &error_abort);
+        object_property_set_uint(obj, "reset-pulldown",
+                                 npcm7xx_gpio[i].reset_pd, &error_abort);
+        object_property_set_uint(obj, "reset-osrc",
+                                 npcm7xx_gpio[i].reset_osrc, &error_abort);
+        object_property_set_uint(obj, "reset-odsc",
+                                 npcm7xx_gpio[i].reset_odsc, &error_abort);
+        sysbus_realize(SYS_BUS_DEVICE(obj), &error_abort);
+        sysbus_mmio_map(SYS_BUS_DEVICE(obj), 0, npcm7xx_gpio[i].regs_addr);
+        sysbus_connect_irq(SYS_BUS_DEVICE(obj), 0,
+                           npcm7xx_irq(s, NPCM7XX_GPIO0_IRQ + i));
+    }
+
     /* USB Host */
     object_property_set_bool(OBJECT(&s->ehci), "companion-enable", true,
                              &error_abort);
diff --git a/hw/gpio/meson.build b/hw/gpio/meson.build
index 86cae9a..5c0a7d7 100644
--- a/hw/gpio/meson.build
+++ b/hw/gpio/meson.build
@@ -6,6 +6,7 @@ softmmu_ss.add(when: 'CONFIG_PUV3', if_true: files('puv3_gpio.c'))
 softmmu_ss.add(when: 'CONFIG_ZAURUS', if_true: files('zaurus.c'))
 
 softmmu_ss.add(when: 'CONFIG_IMX', if_true: files('imx_gpio.c'))
+softmmu_ss.add(when: 'CONFIG_NPCM7XX', if_true: files('npcm7xx_gpio.c'))
 softmmu_ss.add(when: 'CONFIG_NRF51_SOC', if_true: files('nrf51_gpio.c'))
 softmmu_ss.add(when: 'CONFIG_OMAP', if_true: files('omap_gpio.c'))
 softmmu_ss.add(when: 'CONFIG_RASPI', if_true: files('bcm2835_gpio.c'))
diff --git a/hw/gpio/npcm7xx_gpio.c b/hw/gpio/npcm7xx_gpio.c
new file mode 100644
index 0000000..3376901a
--- /dev/null
+++ b/hw/gpio/npcm7xx_gpio.c
@@ -0,0 +1,424 @@
+/*
+ * Nuvoton NPCM7xx General Purpose Input / Output (GPIO)
+ *
+ * Copyright 2020 Google LLC
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include "qemu/osdep.h"
+
+#include "hw/gpio/npcm7xx_gpio.h"
+#include "hw/irq.h"
+#include "hw/qdev-properties.h"
+#include "migration/vmstate.h"
+#include "qapi/error.h"
+#include "qemu/log.h"
+#include "qemu/module.h"
+#include "qemu/units.h"
+#include "trace.h"
+
+/* 32-bit register indices. */
+enum NPCM7xxGPIORegister {
+    NPCM7XX_GPIO_TLOCK1,
+    NPCM7XX_GPIO_DIN,
+    NPCM7XX_GPIO_POL,
+    NPCM7XX_GPIO_DOUT,
+    NPCM7XX_GPIO_OE,
+    NPCM7XX_GPIO_OTYP,
+    NPCM7XX_GPIO_MP,
+    NPCM7XX_GPIO_PU,
+    NPCM7XX_GPIO_PD,
+    NPCM7XX_GPIO_DBNC,
+    NPCM7XX_GPIO_EVTYP,
+    NPCM7XX_GPIO_EVBE,
+    NPCM7XX_GPIO_OBL0,
+    NPCM7XX_GPIO_OBL1,
+    NPCM7XX_GPIO_OBL2,
+    NPCM7XX_GPIO_OBL3,
+    NPCM7XX_GPIO_EVEN,
+    NPCM7XX_GPIO_EVENS,
+    NPCM7XX_GPIO_EVENC,
+    NPCM7XX_GPIO_EVST,
+    NPCM7XX_GPIO_SPLCK,
+    NPCM7XX_GPIO_MPLCK,
+    NPCM7XX_GPIO_IEM,
+    NPCM7XX_GPIO_OSRC,
+    NPCM7XX_GPIO_ODSC,
+    NPCM7XX_GPIO_DOS = 0x68 / sizeof(uint32_t),
+    NPCM7XX_GPIO_DOC,
+    NPCM7XX_GPIO_OES,
+    NPCM7XX_GPIO_OEC,
+    NPCM7XX_GPIO_TLOCK2 = 0x7c / sizeof(uint32_t),
+    NPCM7XX_GPIO_REGS_END,
+};
+
+#define NPCM7XX_GPIO_REGS_SIZE (4 * KiB)
+
+#define NPCM7XX_GPIO_LOCK_MAGIC1 (0xc0defa73)
+#define NPCM7XX_GPIO_LOCK_MAGIC2 (0xc0de1248)
+
+static void npcm7xx_gpio_update_events(NPCM7xxGPIOState *s, uint32_t din_diff)
+{
+    uint32_t din_new = s->regs[NPCM7XX_GPIO_DIN];
+
+    /* Trigger on high level */
+    s->regs[NPCM7XX_GPIO_EVST] |= din_new & ~s->regs[NPCM7XX_GPIO_EVTYP];
+    /* Trigger on both edges */
+    s->regs[NPCM7XX_GPIO_EVST] |= (din_diff & s->regs[NPCM7XX_GPIO_EVTYP]
+                                   & s->regs[NPCM7XX_GPIO_EVBE]);
+    /* Trigger on rising edge */
+    s->regs[NPCM7XX_GPIO_EVST] |= (din_diff & din_new
+                                   & s->regs[NPCM7XX_GPIO_EVTYP]);
+
+    trace_npcm7xx_gpio_update_events(DEVICE(s)->canonical_path,
+                                     s->regs[NPCM7XX_GPIO_EVST],
+                                     s->regs[NPCM7XX_GPIO_EVEN]);
+    qemu_set_irq(s->irq, !!(s->regs[NPCM7XX_GPIO_EVST]
+                            & s->regs[NPCM7XX_GPIO_EVEN]));
+}
+
+static void npcm7xx_gpio_update_pins(NPCM7xxGPIOState *s, uint32_t diff)
+{
+    uint32_t drive_en;
+    uint32_t drive_lvl;
+    uint32_t not_driven;
+    uint32_t undefined;
+    uint32_t pin_diff;
+    uint32_t din_old;
+
+    /* Calculate level of each pin driven by GPIO controller. */
+    drive_lvl = s->regs[NPCM7XX_GPIO_DOUT] ^ s->regs[NPCM7XX_GPIO_POL];
+    /* If OTYP=1, only drive low (open drain) */
+    drive_en = s->regs[NPCM7XX_GPIO_OE] & ~(s->regs[NPCM7XX_GPIO_OTYP]
+                                            & drive_lvl);
+    /*
+     * If a pin is driven to opposite levels by the GPIO controller and the
+     * external driver, the result is undefined.
+     */
+    undefined = drive_en & s->ext_driven & (drive_lvl ^ s->ext_level);
+    if (undefined) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: pins have multiple drivers: 0x%" PRIx32 "\n",
+                      DEVICE(s)->canonical_path, undefined);
+    }
+
+    not_driven = ~(drive_en | s->ext_driven);
+    pin_diff = s->pin_level;
+
+    /* Set pins to externally driven level. */
+    s->pin_level = s->ext_level & s->ext_driven;
+    /* Set internally driven pins, ignoring any conflicts. */
+    s->pin_level |= drive_lvl & drive_en;
+    /* Pull up undriven pins with internal pull-up enabled. */
+    s->pin_level |= not_driven & s->regs[NPCM7XX_GPIO_PU];
+    /* Pins not driven, pulled up or pulled down are undefined */
+    undefined |= not_driven & ~(s->regs[NPCM7XX_GPIO_PU]
+                                | s->regs[NPCM7XX_GPIO_PD]);
+
+    /* If any pins changed state, update the outgoing GPIOs. */
+    pin_diff ^= s->pin_level;
+    pin_diff |= undefined & diff;
+    if (pin_diff) {
+        int i;
+
+        for (i = 0; i < NPCM7XX_GPIO_NR_PINS; i++) {
+            uint32_t mask = BIT(i);
+            if (pin_diff & mask) {
+                int level = (undefined & mask) ? -1 : !!(s->pin_level & mask);
+                trace_npcm7xx_gpio_set_output(DEVICE(s)->canonical_path,
+                                              i, level);
+                qemu_set_irq(s->output[i], level);
+            }
+        }
+    }
+
+    /* Calculate new value of DIN after masking and polarity setting. */
+    din_old = s->regs[NPCM7XX_GPIO_DIN];
+    s->regs[NPCM7XX_GPIO_DIN] = ((s->pin_level & s->regs[NPCM7XX_GPIO_IEM])
+                                 ^ s->regs[NPCM7XX_GPIO_POL]);
+
+    /* See if any new events triggered because of all this. */
+    npcm7xx_gpio_update_events(s, din_old ^ s->regs[NPCM7XX_GPIO_DIN]);
+}
+
+static bool npcm7xx_gpio_is_locked(NPCM7xxGPIOState *s)
+{
+    return s->regs[NPCM7XX_GPIO_TLOCK1] == 1;
+}
+
+static uint64_t npcm7xx_gpio_regs_read(void *opaque, hwaddr addr,
+                                       unsigned int size)
+{
+    hwaddr reg = addr / sizeof(uint32_t);
+    NPCM7xxGPIOState *s = opaque;
+    uint64_t value = 0;
+
+    switch (reg) {
+    case NPCM7XX_GPIO_TLOCK1 ... NPCM7XX_GPIO_EVEN:
+    case NPCM7XX_GPIO_EVST ... NPCM7XX_GPIO_ODSC:
+        value = s->regs[reg];
+        break;
+
+    case NPCM7XX_GPIO_EVENS ... NPCM7XX_GPIO_EVENC:
+    case NPCM7XX_GPIO_DOS ... NPCM7XX_GPIO_TLOCK2:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: read from write-only register 0x%" HWADDR_PRIx "\n",
+                      DEVICE(s)->canonical_path, addr);
+        break;
+
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: read from invalid offset 0x%" HWADDR_PRIx "\n",
+                      DEVICE(s)->canonical_path, addr);
+        break;
+    }
+
+    trace_npcm7xx_gpio_read(DEVICE(s)->canonical_path, addr, value);
+
+    return value;
+}
+
+static void npcm7xx_gpio_regs_write(void *opaque, hwaddr addr, uint64_t v,
+                                    unsigned int size)
+{
+    hwaddr reg = addr / sizeof(uint32_t);
+    NPCM7xxGPIOState *s = opaque;
+    uint32_t value = v;
+    uint32_t diff;
+
+    trace_npcm7xx_gpio_write(DEVICE(s)->canonical_path, addr, v);
+
+    if (npcm7xx_gpio_is_locked(s)) {
+        switch (reg) {
+        case NPCM7XX_GPIO_TLOCK1:
+            if (s->regs[NPCM7XX_GPIO_TLOCK2] == NPCM7XX_GPIO_LOCK_MAGIC2 &&
+                value == NPCM7XX_GPIO_LOCK_MAGIC1) {
+                s->regs[NPCM7XX_GPIO_TLOCK1] = 0;
+                s->regs[NPCM7XX_GPIO_TLOCK2] = 0;
+            }
+            break;
+
+        case NPCM7XX_GPIO_TLOCK2:
+            s->regs[reg] = value;
+            break;
+
+        default:
+            qemu_log_mask(LOG_GUEST_ERROR,
+                          "%s: write to locked register @ 0x%" HWADDR_PRIx "\n",
+                          DEVICE(s)->canonical_path, addr);
+            break;
+        }
+
+        return;
+    }
+
+    diff = s->regs[reg] ^ value;
+
+    switch (reg) {
+    case NPCM7XX_GPIO_TLOCK1:
+    case NPCM7XX_GPIO_TLOCK2:
+        s->regs[NPCM7XX_GPIO_TLOCK1] = 1;
+        s->regs[NPCM7XX_GPIO_TLOCK2] = 0;
+        break;
+
+    case NPCM7XX_GPIO_DIN:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: write to read-only register @ 0x%" HWADDR_PRIx "\n",
+                      DEVICE(s)->canonical_path, addr);
+        break;
+
+    case NPCM7XX_GPIO_POL:
+    case NPCM7XX_GPIO_DOUT:
+    case NPCM7XX_GPIO_OE:
+    case NPCM7XX_GPIO_OTYP:
+    case NPCM7XX_GPIO_PU:
+    case NPCM7XX_GPIO_PD:
+    case NPCM7XX_GPIO_IEM:
+        s->regs[reg] = value;
+        npcm7xx_gpio_update_pins(s, diff);
+        break;
+
+    case NPCM7XX_GPIO_DOS:
+        s->regs[NPCM7XX_GPIO_DOUT] |= value;
+        npcm7xx_gpio_update_pins(s, value);
+        break;
+    case NPCM7XX_GPIO_DOC:
+        s->regs[NPCM7XX_GPIO_DOUT] &= ~value;
+        npcm7xx_gpio_update_pins(s, value);
+        break;
+    case NPCM7XX_GPIO_OES:
+        s->regs[NPCM7XX_GPIO_OE] |= value;
+        npcm7xx_gpio_update_pins(s, value);
+        break;
+    case NPCM7XX_GPIO_OEC:
+        s->regs[NPCM7XX_GPIO_OE] &= ~value;
+        npcm7xx_gpio_update_pins(s, value);
+        break;
+
+    case NPCM7XX_GPIO_EVTYP:
+    case NPCM7XX_GPIO_EVBE:
+    case NPCM7XX_GPIO_EVEN:
+        s->regs[reg] = value;
+        npcm7xx_gpio_update_events(s, 0);
+        break;
+
+    case NPCM7XX_GPIO_EVENS:
+        s->regs[NPCM7XX_GPIO_EVEN] |= value;
+        npcm7xx_gpio_update_events(s, 0);
+        break;
+    case NPCM7XX_GPIO_EVENC:
+        s->regs[NPCM7XX_GPIO_EVEN] &= ~value;
+        npcm7xx_gpio_update_events(s, 0);
+        break;
+
+    case NPCM7XX_GPIO_EVST:
+        s->regs[reg] &= ~value;
+        npcm7xx_gpio_update_events(s, 0);
+        break;
+
+    case NPCM7XX_GPIO_MP:
+    case NPCM7XX_GPIO_DBNC:
+    case NPCM7XX_GPIO_OSRC:
+    case NPCM7XX_GPIO_ODSC:
+        /* Nothing to do; just store the value. */
+        s->regs[reg] = value;
+        break;
+
+    case NPCM7XX_GPIO_OBL0:
+    case NPCM7XX_GPIO_OBL1:
+    case NPCM7XX_GPIO_OBL2:
+    case NPCM7XX_GPIO_OBL3:
+        s->regs[reg] = value;
+        qemu_log_mask(LOG_UNIMP, "%s: Blinking is not implemented\n",
+                      __func__);
+        break;
+
+    case NPCM7XX_GPIO_SPLCK:
+    case NPCM7XX_GPIO_MPLCK:
+        qemu_log_mask(LOG_UNIMP, "%s: Per-pin lock is not implemented\n",
+                      __func__);
+        break;
+
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: write to invalid offset 0x%" HWADDR_PRIx "\n",
+                      DEVICE(s)->canonical_path, addr);
+        break;
+    }
+}
+
+static const MemoryRegionOps npcm7xx_gpio_regs_ops = {
+    .read = npcm7xx_gpio_regs_read,
+    .write = npcm7xx_gpio_regs_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .valid = {
+        .min_access_size = 4,
+        .max_access_size = 4,
+        .unaligned = false,
+    },
+};
+
+static void npcm7xx_gpio_set_input(void *opaque, int line, int level)
+{
+    NPCM7xxGPIOState *s = opaque;
+
+    trace_npcm7xx_gpio_set_input(DEVICE(s)->canonical_path, line, level);
+
+    g_assert(line >= 0 && line < NPCM7XX_GPIO_NR_PINS);
+
+    s->ext_driven = deposit32(s->ext_driven, line, 1, level >= 0);
+    s->ext_level = deposit32(s->ext_level, line, 1, level > 0);
+
+    npcm7xx_gpio_update_pins(s, BIT(line));
+}
+
+static void npcm7xx_gpio_enter_reset(Object *obj, ResetType type)
+{
+    NPCM7xxGPIOState *s = NPCM7XX_GPIO(obj);
+
+    memset(s->regs, 0, sizeof(s->regs));
+
+    s->regs[NPCM7XX_GPIO_PU] = s->reset_pu;
+    s->regs[NPCM7XX_GPIO_PD] = s->reset_pd;
+    s->regs[NPCM7XX_GPIO_OSRC] = s->reset_osrc;
+    s->regs[NPCM7XX_GPIO_ODSC] = s->reset_odsc;
+}
+
+static void npcm7xx_gpio_hold_reset(Object *obj)
+{
+    NPCM7xxGPIOState *s = NPCM7XX_GPIO(obj);
+
+    npcm7xx_gpio_update_pins(s, -1);
+}
+
+static void npcm7xx_gpio_init(Object *obj)
+{
+    NPCM7xxGPIOState *s = NPCM7XX_GPIO(obj);
+    DeviceState *dev = DEVICE(obj);
+
+    memory_region_init_io(&s->mmio, obj, &npcm7xx_gpio_regs_ops, s,
+                          "regs", NPCM7XX_GPIO_REGS_SIZE);
+    sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->mmio);
+    sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->irq);
+
+    qdev_init_gpio_in(dev, npcm7xx_gpio_set_input, NPCM7XX_GPIO_NR_PINS);
+    qdev_init_gpio_out(dev, s->output, NPCM7XX_GPIO_NR_PINS);
+}
+
+static const VMStateDescription vmstate_npcm7xx_gpio = {
+    .name = "npcm7xx-gpio",
+    .version_id = 0,
+    .minimum_version_id = 0,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(pin_level, NPCM7xxGPIOState),
+        VMSTATE_UINT32(ext_level, NPCM7xxGPIOState),
+        VMSTATE_UINT32(ext_driven, NPCM7xxGPIOState),
+        VMSTATE_UINT32_ARRAY(regs, NPCM7xxGPIOState, NPCM7XX_GPIO_NR_REGS),
+        VMSTATE_END_OF_LIST(),
+    },
+};
+
+static Property npcm7xx_gpio_properties[] = {
+    /* Bit n set => pin n has pullup enabled by default. */
+    DEFINE_PROP_UINT32("reset-pullup", NPCM7xxGPIOState, reset_pu, 0),
+    /* Bit n set => pin n has pulldown enabled by default. */
+    DEFINE_PROP_UINT32("reset-pulldown", NPCM7xxGPIOState, reset_pd, 0),
+    /* Bit n set => pin n has high slew rate by default. */
+    DEFINE_PROP_UINT32("reset-osrc", NPCM7xxGPIOState, reset_osrc, 0),
+    /* Bit n set => pin n has high drive strength by default. */
+    DEFINE_PROP_UINT32("reset-odsc", NPCM7xxGPIOState, reset_odsc, 0),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void npcm7xx_gpio_class_init(ObjectClass *klass, void *data)
+{
+    ResettableClass *reset = RESETTABLE_CLASS(klass);
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    QEMU_BUILD_BUG_ON(NPCM7XX_GPIO_REGS_END > NPCM7XX_GPIO_NR_REGS);
+
+    dc->desc = "NPCM7xx GPIO Controller";
+    dc->vmsd = &vmstate_npcm7xx_gpio;
+    reset->phases.enter = npcm7xx_gpio_enter_reset;
+    reset->phases.hold = npcm7xx_gpio_hold_reset;
+    device_class_set_props(dc, npcm7xx_gpio_properties);
+}
+
+static const TypeInfo npcm7xx_gpio_types[] = {
+    {
+        .name = TYPE_NPCM7XX_GPIO,
+        .parent = TYPE_SYS_BUS_DEVICE,
+        .instance_size = sizeof(NPCM7xxGPIOState),
+        .class_init = npcm7xx_gpio_class_init,
+        .instance_init = npcm7xx_gpio_init,
+    },
+};
+DEFINE_TYPES(npcm7xx_gpio_types);
diff --git a/hw/gpio/trace-events b/hw/gpio/trace-events
index 6e3f048..46ab932 100644
--- a/hw/gpio/trace-events
+++ b/hw/gpio/trace-events
@@ -1,5 +1,12 @@
 # See docs/devel/tracing.txt for syntax documentation.
 
+# npcm7xx_gpio.c
+npcm7xx_gpio_read(const char *id, uint64_t offset, uint64_t value) " %s offset: 0x%04" PRIx64 " value 0x%08" PRIx64
+npcm7xx_gpio_write(const char *id, uint64_t offset, uint64_t value) "%s offset: 0x%04" PRIx64 " value 0x%08" PRIx64
+npcm7xx_gpio_set_input(const char *id, int32_t line, int32_t level) "%s line: %" PRIi32 " level: %" PRIi32
+npcm7xx_gpio_set_output(const char *id, int32_t line, int32_t level) "%s line: %" PRIi32 " level: %" PRIi32
+npcm7xx_gpio_update_events(const char *id, uint32_t evst, uint32_t even) "%s evst: 0x%08" PRIx32 " even: 0x%08" PRIx32
+
 # nrf51_gpio.c
 nrf51_gpio_read(uint64_t offset, uint64_t r) "offset 0x%" PRIx64 " value 0x%" PRIx64
 nrf51_gpio_write(uint64_t offset, uint64_t value) "offset 0x%" PRIx64 " value 0x%" PRIx64