This device has the same register layout as the pca9538, but 4 fewer
gpio pins. This commit lowers the number of pins initialised, and reuses
the pca9538 logic.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Hao Wu <wuhaotsh@google.com>
Signed-off-by: Titus Rwantare <titusr@google.com>
---
 hw/gpio/pca_i2c_gpio.c         | 18 ++++++++++++++++++
 include/hw/gpio/pca_i2c_gpio.h |  2 ++
 2 files changed, 20 insertions(+)

diff --git a/hw/gpio/pca_i2c_gpio.c b/hw/gpio/pca_i2c_gpio.c
index 2486c620e3..b911187e34 100644
--- a/hw/gpio/pca_i2c_gpio.c
+++ b/hw/gpio/pca_i2c_gpio.c
@@ -336,6 +336,19 @@ static void pca9538_gpio_class_init(ObjectClass *klass, void *data)
     k->send = pca953x_send;
 }
 
+static void pca9536_gpio_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    I2CSlaveClass *k = I2C_SLAVE_CLASS(klass);
+    PCAGPIOClass *pc = PCA_I2C_GPIO_CLASS(klass);
+
+    dc->desc = "PCA9536 4-bit I/O expander";
+    pc->num_pins = PCA9536_NUM_PINS;
+
+    k->recv = pca953x_recv;
+    k->send = pca953x_send;
+}
+
 static void pca_i2c_gpio_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
@@ -386,6 +399,11 @@ static const TypeInfo pca_gpio_types[] = {
     .parent = TYPE_PCA_I2C_GPIO,
     .class_init = pca9538_gpio_class_init,
     },
+    {
+        .name = TYPE_PCA9536_GPIO,
+        .parent = TYPE_PCA_I2C_GPIO,
+        .class_init = pca9536_gpio_class_init,
+    },
 };
 
 DEFINE_TYPES(pca_gpio_types);
diff --git a/include/hw/gpio/pca_i2c_gpio.h b/include/hw/gpio/pca_i2c_gpio.h
index 61e5853c24..f325563dc7 100644
--- a/include/hw/gpio/pca_i2c_gpio.h
+++ b/include/hw/gpio/pca_i2c_gpio.h
@@ -21,6 +21,7 @@
 #define PCA_I2C_MAX_PINS                     16
 #define PCA6416_NUM_PINS                     16
 #define PCA9538_NUM_PINS                     8
+#define PCA9536_NUM_PINS                     4
 
 typedef struct PCAGPIOClass {
     I2CSlaveClass parent;
@@ -64,5 +65,6 @@ OBJECT_DECLARE_TYPE(PCAGPIOState, PCAGPIOClass, PCA_I2C_GPIO)
 
 #define TYPE_PCA6416_GPIO "pca6416"
 #define TYPE_PCA9538_GPIO "pca9538"
+#define TYPE_PCA9536_GPIO "pca9536"
 
 #endif
-- 
2.47.0.277.g8800431eea-goog