misc/pca955*: Move models under hw/gpio

The PCA9552 and PCA9554 devices are both I2C GPIO controllers and the
PCA9552 also can drive LEDs. Do all the necessary adjustments to move
the models under hw/gpio.

Cc: Glenn Miles <milesg@linux.vnet.ibm.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Message-ID: <20240325134833.1484265-1-clg@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

4 files changed, 815 insertions, 0 deletions

diff --git a/hw/gpio/meson.build b/hw/gpio/meson.build
index 791e93a..a7495d1 100644
--- a/hw/gpio/meson.build
+++ b/hw/gpio/meson.build
@@ -2,6 +2,8 @@ system_ss.add(when: 'CONFIG_GPIO_KEY', if_true: files('gpio_key.c'))
 system_ss.add(when: 'CONFIG_GPIO_MPC8XXX', if_true: files('mpc8xxx.c'))
 system_ss.add(when: 'CONFIG_GPIO_PWR', if_true: files('gpio_pwr.c'))
 system_ss.add(when: 'CONFIG_MAX7310', if_true: files('max7310.c'))
+system_ss.add(when: 'CONFIG_PCA9552', if_true: files('pca9552.c'))
+system_ss.add(when: 'CONFIG_PCA9554', if_true: files('pca9554.c'))
 system_ss.add(when: 'CONFIG_PL061', if_true: files('pl061.c'))
 system_ss.add(when: 'CONFIG_ZAURUS', if_true: files('zaurus.c'))
 
diff --git a/hw/gpio/pca9552.c b/hw/gpio/pca9552.c
new file mode 100644
index 0000000..27d4db0
--- /dev/null
+++ b/hw/gpio/pca9552.c
@@ -0,0 +1,481 @@
+/*
+ * PCA9552 I2C LED blinker
+ *
+ *     https://www.nxp.com/docs/en/application-note/AN264.pdf
+ *
+ * Copyright (c) 2017-2018, IBM Corporation.
+ * Copyright (c) 2020 Philippe Mathieu-Daudé
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later. See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/log.h"
+#include "qemu/module.h"
+#include "qemu/bitops.h"
+#include "hw/qdev-properties.h"
+#include "hw/gpio/pca9552.h"
+#include "hw/gpio/pca9552_regs.h"
+#include "hw/irq.h"
+#include "migration/vmstate.h"
+#include "qapi/error.h"
+#include "qapi/visitor.h"
+#include "trace.h"
+#include "qom/object.h"
+
+struct PCA955xClass {
+    /*< private >*/
+    I2CSlaveClass parent_class;
+    /*< public >*/
+
+    uint8_t pin_count;
+    uint8_t max_reg;
+};
+typedef struct PCA955xClass PCA955xClass;
+
+DECLARE_CLASS_CHECKERS(PCA955xClass, PCA955X,
+                       TYPE_PCA955X)
+/*
+ * Note:  The LED_ON and LED_OFF configuration values for the PCA955X
+ *        chips are the reverse of the PCA953X family of chips.
+ */
+#define PCA9552_LED_ON   0x0
+#define PCA9552_LED_OFF  0x1
+#define PCA9552_LED_PWM0 0x2
+#define PCA9552_LED_PWM1 0x3
+#define PCA9552_PIN_LOW  0x0
+#define PCA9552_PIN_HIZ  0x1
+
+static const char *led_state[] = {"on", "off", "pwm0", "pwm1"};
+
+static uint8_t pca955x_pin_get_config(PCA955xState *s, int pin)
+{
+    uint8_t reg   = PCA9552_LS0 + (pin / 4);
+    uint8_t shift = (pin % 4) << 1;
+
+    return extract32(s->regs[reg], shift, 2);
+}
+
+/* Return INPUT status (bit #N belongs to GPIO #N) */
+static uint16_t pca955x_pins_get_status(PCA955xState *s)
+{
+    return (s->regs[PCA9552_INPUT1] << 8) | s->regs[PCA9552_INPUT0];
+}
+
+static void pca955x_display_pins_status(PCA955xState *s,
+                                        uint16_t previous_pins_status)
+{
+    PCA955xClass *k = PCA955X_GET_CLASS(s);
+    uint16_t pins_status, pins_changed;
+    int i;
+
+    pins_status = pca955x_pins_get_status(s);
+    pins_changed = previous_pins_status ^ pins_status;
+    if (!pins_changed) {
+        return;
+    }
+    if (trace_event_get_state_backends(TRACE_PCA955X_GPIO_STATUS)) {
+        char *buf = g_newa(char, k->pin_count + 1);
+
+        for (i = 0; i < k->pin_count; i++) {
+            if (extract32(pins_status, i, 1)) {
+                buf[i] = '*';
+            } else {
+                buf[i] = '.';
+            }
+        }
+        buf[i] = '\0';
+        trace_pca955x_gpio_status(s->description, buf);
+    }
+    if (trace_event_get_state_backends(TRACE_PCA955X_GPIO_CHANGE)) {
+        for (i = 0; i < k->pin_count; i++) {
+            if (extract32(pins_changed, i, 1)) {
+                unsigned new_state = extract32(pins_status, i, 1);
+
+                /*
+                 * We display the state using the PCA logic ("active-high").
+                 * This is not the state of the LED, which signal might be
+                 * wired "active-low" on the board.
+                 */
+                trace_pca955x_gpio_change(s->description, i,
+                                          !new_state, new_state);
+            }
+        }
+    }
+}
+
+static void pca955x_update_pin_input(PCA955xState *s)
+{
+    PCA955xClass *k = PCA955X_GET_CLASS(s);
+    int i;
+
+    for (i = 0; i < k->pin_count; i++) {
+        uint8_t input_reg = PCA9552_INPUT0 + (i / 8);
+        uint8_t bit_mask = 1 << (i % 8);
+        uint8_t config = pca955x_pin_get_config(s, i);
+        uint8_t old_value = s->regs[input_reg] & bit_mask;
+        uint8_t new_value;
+
+        switch (config) {
+        case PCA9552_LED_ON:
+            /* Pin is set to 0V to turn on LED */
+            s->regs[input_reg] &= ~bit_mask;
+            break;
+        case PCA9552_LED_OFF:
+            /*
+             * Pin is set to Hi-Z to turn off LED and
+             * pullup sets it to a logical 1 unless
+             * external device drives it low.
+             */
+            if (s->ext_state[i] == PCA9552_PIN_LOW) {
+                s->regs[input_reg] &= ~bit_mask;
+            } else {
+                s->regs[input_reg] |=  bit_mask;
+            }
+            break;
+        case PCA9552_LED_PWM0:
+        case PCA9552_LED_PWM1:
+            /* TODO */
+        default:
+            break;
+        }
+
+        /* update irq state only if pin state changed */
+        new_value = s->regs[input_reg] & bit_mask;
+        if (new_value != old_value) {
+            qemu_set_irq(s->gpio_out[i], !!new_value);
+        }
+    }
+}
+
+static uint8_t pca955x_read(PCA955xState *s, uint8_t reg)
+{
+    switch (reg) {
+    case PCA9552_INPUT0:
+    case PCA9552_INPUT1:
+    case PCA9552_PSC0:
+    case PCA9552_PWM0:
+    case PCA9552_PSC1:
+    case PCA9552_PWM1:
+    case PCA9552_LS0:
+    case PCA9552_LS1:
+    case PCA9552_LS2:
+    case PCA9552_LS3:
+        return s->regs[reg];
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: unexpected read to register %d\n",
+                      __func__, reg);
+        return 0xFF;
+    }
+}
+
+static void pca955x_write(PCA955xState *s, uint8_t reg, uint8_t data)
+{
+    uint16_t pins_status;
+
+    switch (reg) {
+    case PCA9552_PSC0:
+    case PCA9552_PWM0:
+    case PCA9552_PSC1:
+    case PCA9552_PWM1:
+        s->regs[reg] = data;
+        break;
+
+    case PCA9552_LS0:
+    case PCA9552_LS1:
+    case PCA9552_LS2:
+    case PCA9552_LS3:
+        pins_status = pca955x_pins_get_status(s);
+        s->regs[reg] = data;
+        pca955x_update_pin_input(s);
+        pca955x_display_pins_status(s, pins_status);
+        break;
+
+    case PCA9552_INPUT0:
+    case PCA9552_INPUT1:
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: unexpected write to register %d\n",
+                      __func__, reg);
+    }
+}
+
+/*
+ * When Auto-Increment is on, the register address is incremented
+ * after each byte is sent to or received by the device. The index
+ * rollovers to 0 when the maximum register address is reached.
+ */
+static void pca955x_autoinc(PCA955xState *s)
+{
+    PCA955xClass *k = PCA955X_GET_CLASS(s);
+
+    if (s->pointer != 0xFF && s->pointer & PCA9552_AUTOINC) {
+        uint8_t reg = s->pointer & 0xf;
+
+        reg = (reg + 1) % (k->max_reg + 1);
+        s->pointer = reg | PCA9552_AUTOINC;
+    }
+}
+
+static uint8_t pca955x_recv(I2CSlave *i2c)
+{
+    PCA955xState *s = PCA955X(i2c);
+    uint8_t ret;
+
+    ret = pca955x_read(s, s->pointer & 0xf);
+
+    /*
+     * From the Specs:
+     *
+     *     Important Note: When a Read sequence is initiated and the
+     *     AI bit is set to Logic Level 1, the Read Sequence MUST
+     *     start by a register different from 0.
+     *
+     * I don't know what should be done in this case, so throw an
+     * error.
+     */
+    if (s->pointer == PCA9552_AUTOINC) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: Autoincrement read starting with register 0\n",
+                      __func__);
+    }
+
+    pca955x_autoinc(s);
+
+    return ret;
+}
+
+static int pca955x_send(I2CSlave *i2c, uint8_t data)
+{
+    PCA955xState *s = PCA955X(i2c);
+
+    /* First byte sent by is the register address */
+    if (s->len == 0) {
+        s->pointer = data;
+        s->len++;
+    } else {
+        pca955x_write(s, s->pointer & 0xf, data);
+
+        pca955x_autoinc(s);
+    }
+
+    return 0;
+}
+
+static int pca955x_event(I2CSlave *i2c, enum i2c_event event)
+{
+    PCA955xState *s = PCA955X(i2c);
+
+    s->len = 0;
+    return 0;
+}
+
+static void pca955x_get_led(Object *obj, Visitor *v, const char *name,
+                            void *opaque, Error **errp)
+{
+    PCA955xClass *k = PCA955X_GET_CLASS(obj);
+    PCA955xState *s = PCA955X(obj);
+    int led, rc, reg;
+    uint8_t state;
+
+    rc = sscanf(name, "led%2d", &led);
+    if (rc != 1) {
+        error_setg(errp, "%s: error reading %s", __func__, name);
+        return;
+    }
+    if (led < 0 || led > k->pin_count) {
+        error_setg(errp, "%s invalid led %s", __func__, name);
+        return;
+    }
+    /*
+     * Get the LSx register as the qom interface should expose the device
+     * state, not the modeled 'input line' behaviour which would come from
+     * reading the INPUTx reg
+     */
+    reg = PCA9552_LS0 + led / 4;
+    state = (pca955x_read(s, reg) >> ((led % 4) * 2)) & 0x3;
+    visit_type_str(v, name, (char **)&led_state[state], errp);
+}
+
+/*
+ * Return an LED selector register value based on an existing one, with
+ * the appropriate 2-bit state value set for the given LED number (0-3).
+ */
+static inline uint8_t pca955x_ledsel(uint8_t oldval, int led_num, int state)
+{
+        return (oldval & (~(0x3 << (led_num << 1)))) |
+                ((state & 0x3) << (led_num << 1));
+}
+
+static void pca955x_set_led(Object *obj, Visitor *v, const char *name,
+                            void *opaque, Error **errp)
+{
+    PCA955xClass *k = PCA955X_GET_CLASS(obj);
+    PCA955xState *s = PCA955X(obj);
+    int led, rc, reg, val;
+    uint8_t state;
+    char *state_str;
+
+    if (!visit_type_str(v, name, &state_str, errp)) {
+        return;
+    }
+    rc = sscanf(name, "led%2d", &led);
+    if (rc != 1) {
+        error_setg(errp, "%s: error reading %s", __func__, name);
+        return;
+    }
+    if (led < 0 || led > k->pin_count) {
+        error_setg(errp, "%s invalid led %s", __func__, name);
+        return;
+    }
+
+    for (state = 0; state < ARRAY_SIZE(led_state); state++) {
+        if (!strcmp(state_str, led_state[state])) {
+            break;
+        }
+    }
+    if (state >= ARRAY_SIZE(led_state)) {
+        error_setg(errp, "%s invalid led state %s", __func__, state_str);
+        return;
+    }
+
+    reg = PCA9552_LS0 + led / 4;
+    val = pca955x_read(s, reg);
+    val = pca955x_ledsel(val, led % 4, state);
+    pca955x_write(s, reg, val);
+}
+
+static const VMStateDescription pca9552_vmstate = {
+    .name = "PCA9552",
+    .version_id = 0,
+    .minimum_version_id = 0,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT8(len, PCA955xState),
+        VMSTATE_UINT8(pointer, PCA955xState),
+        VMSTATE_UINT8_ARRAY(regs, PCA955xState, PCA955X_NR_REGS),
+        VMSTATE_UINT8_ARRAY(ext_state, PCA955xState, PCA955X_PIN_COUNT_MAX),
+        VMSTATE_I2C_SLAVE(i2c, PCA955xState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void pca9552_reset(DeviceState *dev)
+{
+    PCA955xState *s = PCA955X(dev);
+
+    s->regs[PCA9552_PSC0] = 0xFF;
+    s->regs[PCA9552_PWM0] = 0x80;
+    s->regs[PCA9552_PSC1] = 0xFF;
+    s->regs[PCA9552_PWM1] = 0x80;
+    s->regs[PCA9552_LS0] = 0x55; /* all OFF */
+    s->regs[PCA9552_LS1] = 0x55;
+    s->regs[PCA9552_LS2] = 0x55;
+    s->regs[PCA9552_LS3] = 0x55;
+
+    memset(s->ext_state, PCA9552_PIN_HIZ, PCA955X_PIN_COUNT_MAX);
+    pca955x_update_pin_input(s);
+
+    s->pointer = 0xFF;
+    s->len = 0;
+}
+
+static void pca955x_initfn(Object *obj)
+{
+    PCA955xClass *k = PCA955X_GET_CLASS(obj);
+    int led;
+
+    assert(k->pin_count <= PCA955X_PIN_COUNT_MAX);
+    for (led = 0; led < k->pin_count; led++) {
+        char *name;
+
+        name = g_strdup_printf("led%d", led);
+        object_property_add(obj, name, "bool", pca955x_get_led, pca955x_set_led,
+                            NULL, NULL);
+        g_free(name);
+    }
+}
+
+static void pca955x_set_ext_state(PCA955xState *s, int pin, int level)
+{
+    if (s->ext_state[pin] != level) {
+        uint16_t pins_status = pca955x_pins_get_status(s);
+        s->ext_state[pin] = level;
+        pca955x_update_pin_input(s);
+        pca955x_display_pins_status(s, pins_status);
+    }
+}
+
+static void pca955x_gpio_in_handler(void *opaque, int pin, int level)
+{
+
+    PCA955xState *s = PCA955X(opaque);
+    PCA955xClass *k = PCA955X_GET_CLASS(s);
+
+    assert((pin >= 0) && (pin < k->pin_count));
+    pca955x_set_ext_state(s, pin, level);
+}
+
+static void pca955x_realize(DeviceState *dev, Error **errp)
+{
+    PCA955xClass *k = PCA955X_GET_CLASS(dev);
+    PCA955xState *s = PCA955X(dev);
+
+    if (!s->description) {
+        s->description = g_strdup("pca-unspecified");
+    }
+
+    qdev_init_gpio_out(dev, s->gpio_out, k->pin_count);
+    qdev_init_gpio_in(dev, pca955x_gpio_in_handler, k->pin_count);
+}
+
+static Property pca955x_properties[] = {
+    DEFINE_PROP_STRING("description", PCA955xState, description),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void pca955x_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    I2CSlaveClass *k = I2C_SLAVE_CLASS(klass);
+
+    k->event = pca955x_event;
+    k->recv = pca955x_recv;
+    k->send = pca955x_send;
+    dc->realize = pca955x_realize;
+    device_class_set_props(dc, pca955x_properties);
+}
+
+static const TypeInfo pca955x_info = {
+    .name          = TYPE_PCA955X,
+    .parent        = TYPE_I2C_SLAVE,
+    .instance_init = pca955x_initfn,
+    .instance_size = sizeof(PCA955xState),
+    .class_init    = pca955x_class_init,
+    .class_size    = sizeof(PCA955xClass),
+    .abstract      = true,
+};
+
+static void pca9552_class_init(ObjectClass *oc, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(oc);
+    PCA955xClass *pc = PCA955X_CLASS(oc);
+
+    dc->reset = pca9552_reset;
+    dc->vmsd = &pca9552_vmstate;
+    pc->max_reg = PCA9552_LS3;
+    pc->pin_count = 16;
+}
+
+static const TypeInfo pca9552_info = {
+    .name          = TYPE_PCA9552,
+    .parent        = TYPE_PCA955X,
+    .class_init    = pca9552_class_init,
+};
+
+static void pca955x_register_types(void)
+{
+    type_register_static(&pca955x_info);
+    type_register_static(&pca9552_info);
+}
+
+type_init(pca955x_register_types)
diff --git a/hw/gpio/pca9554.c b/hw/gpio/pca9554.c
new file mode 100644
index 0000000..affc9b2
--- /dev/null
+++ b/hw/gpio/pca9554.c
@@ -0,0 +1,328 @@
+/*
+ * PCA9554 I/O port
+ *
+ * Copyright (c) 2023, IBM Corporation.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/log.h"
+#include "qemu/module.h"
+#include "qemu/bitops.h"
+#include "hw/qdev-properties.h"
+#include "hw/gpio/pca9554.h"
+#include "hw/gpio/pca9554_regs.h"
+#include "hw/irq.h"
+#include "migration/vmstate.h"
+#include "qapi/error.h"
+#include "qapi/visitor.h"
+#include "trace.h"
+#include "qom/object.h"
+
+struct PCA9554Class {
+    /*< private >*/
+    I2CSlaveClass parent_class;
+    /*< public >*/
+};
+typedef struct PCA9554Class PCA9554Class;
+
+DECLARE_CLASS_CHECKERS(PCA9554Class, PCA9554,
+                       TYPE_PCA9554)
+
+#define PCA9554_PIN_LOW  0x0
+#define PCA9554_PIN_HIZ  0x1
+
+static const char *pin_state[] = {"low", "high"};
+
+static void pca9554_update_pin_input(PCA9554State *s)
+{
+    int i;
+    uint8_t config = s->regs[PCA9554_CONFIG];
+    uint8_t output = s->regs[PCA9554_OUTPUT];
+    uint8_t internal_state = config | output;
+
+    for (i = 0; i < PCA9554_PIN_COUNT; i++) {
+        uint8_t bit_mask = 1 << i;
+        uint8_t internal_pin_state = (internal_state >> i) & 0x1;
+        uint8_t old_value = s->regs[PCA9554_INPUT] & bit_mask;
+        uint8_t new_value;
+
+        switch (internal_pin_state) {
+        case PCA9554_PIN_LOW:
+            s->regs[PCA9554_INPUT] &= ~bit_mask;
+            break;
+        case PCA9554_PIN_HIZ:
+            /*
+             * pullup sets it to a logical 1 unless
+             * external device drives it low.
+             */
+            if (s->ext_state[i] == PCA9554_PIN_LOW) {
+                s->regs[PCA9554_INPUT] &= ~bit_mask;
+            } else {
+                s->regs[PCA9554_INPUT] |=  bit_mask;
+            }
+            break;
+        default:
+            break;
+        }
+
+        /* update irq state only if pin state changed */
+        new_value = s->regs[PCA9554_INPUT] & bit_mask;
+        if (new_value != old_value) {
+            if (new_value) {
+                /* changed from 0 to 1 */
+                qemu_set_irq(s->gpio_out[i], 1);
+            } else {
+                /* changed from 1 to 0 */
+                qemu_set_irq(s->gpio_out[i], 0);
+            }
+        }
+    }
+}
+
+static uint8_t pca9554_read(PCA9554State *s, uint8_t reg)
+{
+    switch (reg) {
+    case PCA9554_INPUT:
+        return s->regs[PCA9554_INPUT] ^ s->regs[PCA9554_POLARITY];
+    case PCA9554_OUTPUT:
+    case PCA9554_POLARITY:
+    case PCA9554_CONFIG:
+        return s->regs[reg];
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: unexpected read to register %d\n",
+                      __func__, reg);
+        return 0xFF;
+    }
+}
+
+static void pca9554_write(PCA9554State *s, uint8_t reg, uint8_t data)
+{
+    switch (reg) {
+    case PCA9554_OUTPUT:
+    case PCA9554_CONFIG:
+        s->regs[reg] = data;
+        pca9554_update_pin_input(s);
+        break;
+    case PCA9554_POLARITY:
+        s->regs[reg] = data;
+        break;
+    case PCA9554_INPUT:
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: unexpected write to register %d\n",
+                      __func__, reg);
+    }
+}
+
+static uint8_t pca9554_recv(I2CSlave *i2c)
+{
+    PCA9554State *s = PCA9554(i2c);
+    uint8_t ret;
+
+    ret = pca9554_read(s, s->pointer & 0x3);
+
+    return ret;
+}
+
+static int pca9554_send(I2CSlave *i2c, uint8_t data)
+{
+    PCA9554State *s = PCA9554(i2c);
+
+    /* First byte sent by is the register address */
+    if (s->len == 0) {
+        s->pointer = data;
+        s->len++;
+    } else {
+        pca9554_write(s, s->pointer & 0x3, data);
+    }
+
+    return 0;
+}
+
+static int pca9554_event(I2CSlave *i2c, enum i2c_event event)
+{
+    PCA9554State *s = PCA9554(i2c);
+
+    s->len = 0;
+    return 0;
+}
+
+static void pca9554_get_pin(Object *obj, Visitor *v, const char *name,
+                            void *opaque, Error **errp)
+{
+    PCA9554State *s = PCA9554(obj);
+    int pin, rc;
+    uint8_t state;
+
+    rc = sscanf(name, "pin%2d", &pin);
+    if (rc != 1) {
+        error_setg(errp, "%s: error reading %s", __func__, name);
+        return;
+    }
+    if (pin < 0 || pin > PCA9554_PIN_COUNT) {
+        error_setg(errp, "%s invalid pin %s", __func__, name);
+        return;
+    }
+
+    state = pca9554_read(s, PCA9554_CONFIG);
+    state |= pca9554_read(s, PCA9554_OUTPUT);
+    state = (state >> pin) & 0x1;
+    visit_type_str(v, name, (char **)&pin_state[state], errp);
+}
+
+static void pca9554_set_pin(Object *obj, Visitor *v, const char *name,
+                            void *opaque, Error **errp)
+{
+    PCA9554State *s = PCA9554(obj);
+    int pin, rc, val;
+    uint8_t state, mask;
+    char *state_str;
+
+    if (!visit_type_str(v, name, &state_str, errp)) {
+        return;
+    }
+    rc = sscanf(name, "pin%2d", &pin);
+    if (rc != 1) {
+        error_setg(errp, "%s: error reading %s", __func__, name);
+        return;
+    }
+    if (pin < 0 || pin > PCA9554_PIN_COUNT) {
+        error_setg(errp, "%s invalid pin %s", __func__, name);
+        return;
+    }
+
+    for (state = 0; state < ARRAY_SIZE(pin_state); state++) {
+        if (!strcmp(state_str, pin_state[state])) {
+            break;
+        }
+    }
+    if (state >= ARRAY_SIZE(pin_state)) {
+        error_setg(errp, "%s invalid pin state %s", __func__, state_str);
+        return;
+    }
+
+    /* First, modify the output register bit */
+    val = pca9554_read(s, PCA9554_OUTPUT);
+    mask = 0x1 << pin;
+    if (state == PCA9554_PIN_LOW) {
+        val &= ~(mask);
+    } else {
+        val |= mask;
+    }
+    pca9554_write(s, PCA9554_OUTPUT, val);
+
+    /* Then, clear the config register bit for output mode */
+    val = pca9554_read(s, PCA9554_CONFIG);
+    val &= ~mask;
+    pca9554_write(s, PCA9554_CONFIG, val);
+}
+
+static const VMStateDescription pca9554_vmstate = {
+    .name = "PCA9554",
+    .version_id = 0,
+    .minimum_version_id = 0,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT8(len, PCA9554State),
+        VMSTATE_UINT8(pointer, PCA9554State),
+        VMSTATE_UINT8_ARRAY(regs, PCA9554State, PCA9554_NR_REGS),
+        VMSTATE_UINT8_ARRAY(ext_state, PCA9554State, PCA9554_PIN_COUNT),
+        VMSTATE_I2C_SLAVE(i2c, PCA9554State),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void pca9554_reset(DeviceState *dev)
+{
+    PCA9554State *s = PCA9554(dev);
+
+    s->regs[PCA9554_INPUT] = 0xFF;
+    s->regs[PCA9554_OUTPUT] = 0xFF;
+    s->regs[PCA9554_POLARITY] = 0x0; /* No pins are inverted */
+    s->regs[PCA9554_CONFIG] = 0xFF; /* All pins are inputs */
+
+    memset(s->ext_state, PCA9554_PIN_HIZ, PCA9554_PIN_COUNT);
+    pca9554_update_pin_input(s);
+
+    s->pointer = 0x0;
+    s->len = 0;
+}
+
+static void pca9554_initfn(Object *obj)
+{
+    int pin;
+
+    for (pin = 0; pin < PCA9554_PIN_COUNT; pin++) {
+        char *name;
+
+        name = g_strdup_printf("pin%d", pin);
+        object_property_add(obj, name, "bool", pca9554_get_pin, pca9554_set_pin,
+                            NULL, NULL);
+        g_free(name);
+    }
+}
+
+static void pca9554_set_ext_state(PCA9554State *s, int pin, int level)
+{
+    if (s->ext_state[pin] != level) {
+        s->ext_state[pin] = level;
+        pca9554_update_pin_input(s);
+    }
+}
+
+static void pca9554_gpio_in_handler(void *opaque, int pin, int level)
+{
+
+    PCA9554State *s = PCA9554(opaque);
+
+    assert((pin >= 0) && (pin < PCA9554_PIN_COUNT));
+    pca9554_set_ext_state(s, pin, level);
+}
+
+static void pca9554_realize(DeviceState *dev, Error **errp)
+{
+    PCA9554State *s = PCA9554(dev);
+
+    if (!s->description) {
+        s->description = g_strdup("pca9554");
+    }
+
+    qdev_init_gpio_out(dev, s->gpio_out, PCA9554_PIN_COUNT);
+    qdev_init_gpio_in(dev, pca9554_gpio_in_handler, PCA9554_PIN_COUNT);
+}
+
+static Property pca9554_properties[] = {
+    DEFINE_PROP_STRING("description", PCA9554State, description),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void pca9554_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    I2CSlaveClass *k = I2C_SLAVE_CLASS(klass);
+
+    k->event = pca9554_event;
+    k->recv = pca9554_recv;
+    k->send = pca9554_send;
+    dc->realize = pca9554_realize;
+    dc->reset = pca9554_reset;
+    dc->vmsd = &pca9554_vmstate;
+    device_class_set_props(dc, pca9554_properties);
+}
+
+static const TypeInfo pca9554_info = {
+    .name          = TYPE_PCA9554,
+    .parent        = TYPE_I2C_SLAVE,
+    .instance_init = pca9554_initfn,
+    .instance_size = sizeof(PCA9554State),
+    .class_init    = pca9554_class_init,
+    .class_size    = sizeof(PCA9554Class),
+    .abstract      = false,
+};
+
+static void pca9554_register_types(void)
+{
+    type_register_static(&pca9554_info);
+}
+
+type_init(pca9554_register_types)
diff --git a/hw/gpio/trace-events b/hw/gpio/trace-events
index 9331f42..b91cc7e 100644
--- a/hw/gpio/trace-events
+++ b/hw/gpio/trace-events
@@ -13,6 +13,10 @@ nrf51_gpio_write(uint64_t offset, uint64_t value) "offset 0x%" PRIx64 " value 0x
 nrf51_gpio_set(int64_t line, int64_t value) "line %" PRIi64 " value %" PRIi64
 nrf51_gpio_update_output_irq(int64_t line, int64_t value) "line %" PRIi64 " value %" PRIi64
 
+# pca9552.c
+pca955x_gpio_status(const char *description, const char *buf) "%s GPIOs 0-15 [%s]"
+pca955x_gpio_change(const char *description, unsigned id, unsigned prev_state, unsigned current_state) "%s GPIO id:%u status: %u -> %u"
+
 # pl061.c
 pl061_update(const char *id, uint32_t dir, uint32_t data, uint32_t pullups, uint32_t floating) "%s GPIODIR 0x%x GPIODATA 0x%x pullups 0x%x floating 0x%x"
 pl061_set_output(const char *id, int gpio, int level) "%s setting output %d to %d"