Extend the 16-bit PCA9552 model to support non-LED devices such as
the PCA9535[1].
[1]: https://www.ti.com/lit/ds/symlink/pca9535.pdf
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
---
hw/gpio/pca9552.c | 176 ++++++++++++++++++++++++++++-------------
include/hw/gpio/pca9552.h | 1 +
include/hw/gpio/pca9552_regs.h | 10 +++
3 files changed, 133 insertions(+), 54 deletions(-)
diff --git a/hw/gpio/pca9552.c b/hw/gpio/pca9552.c
index dd3c795e49..dd3f1536b6 100644
--- a/hw/gpio/pca9552.c
+++ b/hw/gpio/pca9552.c
@@ -31,6 +31,7 @@ struct PCA955xClass {
uint8_t pin_count;
uint8_t max_reg;
+ bool has_led_support;
};
typedef struct PCA955xClass PCA955xClass;
@@ -113,32 +114,59 @@ static void pca955x_update_pin_input(PCA955xState *s)
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) {
+ if (k->has_led_support) {
+ /* PCA9552: LED control behavior */
+ uint8_t config = pca955x_pin_get_config(s, i);
+
+ 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;
+ }
+ } else {
+ /* PCA9535: Simple GPIO behavior */
+ uint8_t config_reg = PCA9535_CONFIG0 + (i / 8);
+ uint8_t output_reg = PCA9535_OUTPUT0 + (i / 8);
+ uint8_t polarity_reg = PCA9535_POLARITY0 + (i / 8);
+
+ /* Check if pin is configured as input */
+ if (s->regs[config_reg] & bit_mask) {
+ /* Input mode - reflect external state */
+ if (s->ext_state[i] == PCA9552_PIN_LOW) {
+ s->regs[input_reg] &= ~bit_mask;
+ } else {
+ s->regs[input_reg] |= bit_mask;
+ }
} else {
- s->regs[input_reg] |= bit_mask;
+ /* Output mode - reflect output register value */
+ uint8_t output_bit = s->regs[output_reg] & bit_mask;
+ uint8_t polarity_bit = s->regs[polarity_reg] & bit_mask;
+
+ /* Apply polarity inversion if set */
+ s->regs[input_reg] = (s->regs[input_reg] & ~bit_mask) |
+ ((output_bit ^ polarity_bit) & bit_mask);
}
- break;
- case PCA9552_LED_PWM0:
- case PCA9552_LED_PWM1:
- /* TODO */
- default:
- break;
}
/* update irq state only if pin state changed */
@@ -151,52 +179,52 @@ static void pca955x_update_pin_input(PCA955xState *s)
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:
+ PCA955xClass *k = PCA955X_GET_CLASS(s);
+
+ if (reg > k->max_reg) {
qemu_log_mask(LOG_GUEST_ERROR, "%s: unexpected read to register %d\n",
__func__, reg);
return 0xFF;
}
+
+ return s->regs[reg];
}
static void pca955x_write(PCA955xState *s, uint8_t reg, uint8_t data)
{
+ PCA955xClass *k = PCA955X_GET_CLASS(s);
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:
+ if (reg > k->max_reg) {
qemu_log_mask(LOG_GUEST_ERROR, "%s: unexpected write to register %d\n",
__func__, reg);
+ return;
+ }
+
+ /* Handle read-only registers */
+ if (reg == PCA9552_INPUT0 || reg == PCA9552_INPUT1) {
+ qemu_log_mask(LOG_GUEST_ERROR,
+ "%s: unexpected write to read-only register %d\n",
+ __func__, reg);
+ return;
+ }
+
+ pins_status = pca955x_pins_get_status(s);
+ s->regs[reg] = data;
+
+ /* Update GPIO state if this register affects outputs */
+ if (k->has_led_support) {
+ /* PCA9552: Update on LED selector register writes */
+ if (reg >= PCA9552_LS0 && reg <= PCA9552_LS3) {
+ pca955x_update_pin_input(s);
+ pca955x_display_pins_status(s, pins_status);
+ }
+ } else {
+ /* PCA9535: Update on OUTPUT, POLARITY, or CONFIG register writes */
+ if (reg >= PCA9535_OUTPUT0 && reg <= PCA9535_CONFIG1) {
+ pca955x_update_pin_input(s);
+ pca955x_display_pins_status(s, pins_status);
+ }
}
}
@@ -379,6 +407,26 @@ static void pca9552_reset(DeviceState *dev)
s->len = 0;
}
+static void pca9535_reset(DeviceState *dev)
+{
+ PCA955xState *s = PCA955X(dev);
+
+ s->regs[PCA9535_INPUT0] = 0xFF; /* All inputs high (pull-ups) */
+ s->regs[PCA9535_INPUT1] = 0xFF; /* All inputs high (pull-ups) */
+ s->regs[PCA9535_OUTPUT0] = 0xFF; /* All outputs high */
+ s->regs[PCA9535_OUTPUT1] = 0xFF; /* All outputs high */
+ s->regs[PCA9535_POLARITY0] = 0x00; /* No polarity inversion */
+ s->regs[PCA9535_POLARITY1] = 0x00; /* No polarity inversion */
+ s->regs[PCA9535_CONFIG0] = 0xFF; /* All pins as inputs */
+ s->regs[PCA9535_CONFIG1] = 0xFF; /* All pins as inputs */
+
+ 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);
@@ -463,6 +511,19 @@ static void pca9552_class_init(ObjectClass *oc, const void *data)
dc->vmsd = &pca9552_vmstate;
pc->max_reg = PCA9552_LS3;
pc->pin_count = 16;
+ pc->has_led_support = true;
+}
+
+static void pca9535_class_init(ObjectClass *oc, const void *data)
+{
+ DeviceClass *dc = DEVICE_CLASS(oc);
+ PCA955xClass *pc = PCA955X_CLASS(oc);
+
+ device_class_set_legacy_reset(dc, pca9535_reset);
+ dc->vmsd = &pca9552_vmstate;
+ pc->max_reg = PCA9535_CONFIG1;
+ pc->pin_count = 16;
+ pc->has_led_support = false;
}
static const TypeInfo pca9552_info = {
@@ -471,10 +532,17 @@ static const TypeInfo pca9552_info = {
.class_init = pca9552_class_init,
};
+static const TypeInfo pca9535_info = {
+ .name = TYPE_PCA9535,
+ .parent = TYPE_PCA955X,
+ .class_init = pca9535_class_init,
+};
+
static void pca955x_register_types(void)
{
type_register_static(&pca955x_info);
type_register_static(&pca9552_info);
+ type_register_static(&pca9535_info);
}
type_init(pca955x_register_types)
diff --git a/include/hw/gpio/pca9552.h b/include/hw/gpio/pca9552.h
index c36525f0c3..43b175235d 100644
--- a/include/hw/gpio/pca9552.h
+++ b/include/hw/gpio/pca9552.h
@@ -14,6 +14,7 @@
#define TYPE_PCA9552 "pca9552"
#define TYPE_PCA955X "pca955x"
+#define TYPE_PCA9535 "pca9535"
typedef struct PCA955xState PCA955xState;
DECLARE_INSTANCE_CHECKER(PCA955xState, PCA955X,
TYPE_PCA955X)
diff --git a/include/hw/gpio/pca9552_regs.h b/include/hw/gpio/pca9552_regs.h
index d8051cfbd6..5a6bb03396 100644
--- a/include/hw/gpio/pca9552_regs.h
+++ b/include/hw/gpio/pca9552_regs.h
@@ -29,4 +29,14 @@
*/
#define PCA9552_AUTOINC (1 << 4)
+/* PCA9535 Registers (same addresses, different semantics) */
+#define PCA9535_INPUT0 0 /* read only input register 0 */
+#define PCA9535_INPUT1 1 /* read only input register 1 */
+#define PCA9535_OUTPUT0 2 /* read/write output register 0 */
+#define PCA9535_OUTPUT1 3 /* read/write output register 1 */
+#define PCA9535_POLARITY0 4 /* read/write polarity inversion register 0 */
+#define PCA9535_POLARITY1 5 /* read/write polarity inversion register 1 */
+#define PCA9535_CONFIG0 6 /* read/write configuration register 0 */
+#define PCA9535_CONFIG1 7 /* read/write configuration register 1 */
+
#endif
--
2.51.2Looks good.
Reviewed-by: Glenn Miles <milesg@linux.ibm.com>
Thanks,
Glenn
On Wed, 2026-01-21 at 13:17 -0500, Patrick Williams wrote:
> Extend the 16-bit PCA9552 model to support non-LED devices such as
> the PCA9535[1].
>
> [1]: https://www.ti.com/lit/ds/symlink/pca9535.pdf
>
> Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
> ---
> hw/gpio/pca9552.c | 176 ++++++++++++++++++++++++++++-------------
> include/hw/gpio/pca9552.h | 1 +
> include/hw/gpio/pca9552_regs.h | 10 +++
> 3 files changed, 133 insertions(+), 54 deletions(-)
>
> diff --git a/hw/gpio/pca9552.c b/hw/gpio/pca9552.c
> index dd3c795e49..dd3f1536b6 100644
> --- a/hw/gpio/pca9552.c
> +++ b/hw/gpio/pca9552.c
> @@ -31,6 +31,7 @@ struct PCA955xClass {
>
> uint8_t pin_count;
> uint8_t max_reg;
> + bool has_led_support;
> };
> typedef struct PCA955xClass PCA955xClass;
>
> @@ -113,32 +114,59 @@ static void pca955x_update_pin_input(PCA955xState *s)
> 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) {
> + if (k->has_led_support) {
> + /* PCA9552: LED control behavior */
> + uint8_t config = pca955x_pin_get_config(s, i);
> +
> + 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;
> + }
> + } else {
> + /* PCA9535: Simple GPIO behavior */
> + uint8_t config_reg = PCA9535_CONFIG0 + (i / 8);
> + uint8_t output_reg = PCA9535_OUTPUT0 + (i / 8);
> + uint8_t polarity_reg = PCA9535_POLARITY0 + (i / 8);
> +
> + /* Check if pin is configured as input */
> + if (s->regs[config_reg] & bit_mask) {
> + /* Input mode - reflect external state */
> + if (s->ext_state[i] == PCA9552_PIN_LOW) {
> + s->regs[input_reg] &= ~bit_mask;
> + } else {
> + s->regs[input_reg] |= bit_mask;
> + }
> } else {
> - s->regs[input_reg] |= bit_mask;
> + /* Output mode - reflect output register value */
> + uint8_t output_bit = s->regs[output_reg] & bit_mask;
> + uint8_t polarity_bit = s->regs[polarity_reg] & bit_mask;
> +
> + /* Apply polarity inversion if set */
> + s->regs[input_reg] = (s->regs[input_reg] & ~bit_mask) |
> + ((output_bit ^ polarity_bit) & bit_mask);
> }
> - break;
> - case PCA9552_LED_PWM0:
> - case PCA9552_LED_PWM1:
> - /* TODO */
> - default:
> - break;
> }
>
> /* update irq state only if pin state changed */
> @@ -151,52 +179,52 @@ static void pca955x_update_pin_input(PCA955xState *s)
>
> 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:
> + PCA955xClass *k = PCA955X_GET_CLASS(s);
> +
> + if (reg > k->max_reg) {
> qemu_log_mask(LOG_GUEST_ERROR, "%s: unexpected read to register %d\n",
> __func__, reg);
> return 0xFF;
> }
> +
> + return s->regs[reg];
> }
>
> static void pca955x_write(PCA955xState *s, uint8_t reg, uint8_t data)
> {
> + PCA955xClass *k = PCA955X_GET_CLASS(s);
> 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:
> + if (reg > k->max_reg) {
> qemu_log_mask(LOG_GUEST_ERROR, "%s: unexpected write to register %d\n",
> __func__, reg);
> + return;
> + }
> +
> + /* Handle read-only registers */
> + if (reg == PCA9552_INPUT0 || reg == PCA9552_INPUT1) {
> + qemu_log_mask(LOG_GUEST_ERROR,
> + "%s: unexpected write to read-only register %d\n",
> + __func__, reg);
> + return;
> + }
> +
> + pins_status = pca955x_pins_get_status(s);
> + s->regs[reg] = data;
> +
> + /* Update GPIO state if this register affects outputs */
> + if (k->has_led_support) {
> + /* PCA9552: Update on LED selector register writes */
> + if (reg >= PCA9552_LS0 && reg <= PCA9552_LS3) {
> + pca955x_update_pin_input(s);
> + pca955x_display_pins_status(s, pins_status);
> + }
> + } else {
> + /* PCA9535: Update on OUTPUT, POLARITY, or CONFIG register writes */
> + if (reg >= PCA9535_OUTPUT0 && reg <= PCA9535_CONFIG1) {
> + pca955x_update_pin_input(s);
> + pca955x_display_pins_status(s, pins_status);
> + }
> }
> }
>
> @@ -379,6 +407,26 @@ static void pca9552_reset(DeviceState *dev)
> s->len = 0;
> }
>
> +static void pca9535_reset(DeviceState *dev)
> +{
> + PCA955xState *s = PCA955X(dev);
> +
> + s->regs[PCA9535_INPUT0] = 0xFF; /* All inputs high (pull-ups) */
> + s->regs[PCA9535_INPUT1] = 0xFF; /* All inputs high (pull-ups) */
> + s->regs[PCA9535_OUTPUT0] = 0xFF; /* All outputs high */
> + s->regs[PCA9535_OUTPUT1] = 0xFF; /* All outputs high */
> + s->regs[PCA9535_POLARITY0] = 0x00; /* No polarity inversion */
> + s->regs[PCA9535_POLARITY1] = 0x00; /* No polarity inversion */
> + s->regs[PCA9535_CONFIG0] = 0xFF; /* All pins as inputs */
> + s->regs[PCA9535_CONFIG1] = 0xFF; /* All pins as inputs */
> +
> + 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);
> @@ -463,6 +511,19 @@ static void pca9552_class_init(ObjectClass *oc, const void *data)
> dc->vmsd = &pca9552_vmstate;
> pc->max_reg = PCA9552_LS3;
> pc->pin_count = 16;
> + pc->has_led_support = true;
> +}
> +
> +static void pca9535_class_init(ObjectClass *oc, const void *data)
> +{
> + DeviceClass *dc = DEVICE_CLASS(oc);
> + PCA955xClass *pc = PCA955X_CLASS(oc);
> +
> + device_class_set_legacy_reset(dc, pca9535_reset);
> + dc->vmsd = &pca9552_vmstate;
> + pc->max_reg = PCA9535_CONFIG1;
> + pc->pin_count = 16;
> + pc->has_led_support = false;
> }
>
> static const TypeInfo pca9552_info = {
> @@ -471,10 +532,17 @@ static const TypeInfo pca9552_info = {
> .class_init = pca9552_class_init,
> };
>
> +static const TypeInfo pca9535_info = {
> + .name = TYPE_PCA9535,
> + .parent = TYPE_PCA955X,
> + .class_init = pca9535_class_init,
> +};
> +
> static void pca955x_register_types(void)
> {
> type_register_static(&pca955x_info);
> type_register_static(&pca9552_info);
> + type_register_static(&pca9535_info);
> }
>
> type_init(pca955x_register_types)
> diff --git a/include/hw/gpio/pca9552.h b/include/hw/gpio/pca9552.h
> index c36525f0c3..43b175235d 100644
> --- a/include/hw/gpio/pca9552.h
> +++ b/include/hw/gpio/pca9552.h
> @@ -14,6 +14,7 @@
>
> #define TYPE_PCA9552 "pca9552"
> #define TYPE_PCA955X "pca955x"
> +#define TYPE_PCA9535 "pca9535"
> typedef struct PCA955xState PCA955xState;
> DECLARE_INSTANCE_CHECKER(PCA955xState, PCA955X,
> TYPE_PCA955X)
> diff --git a/include/hw/gpio/pca9552_regs.h b/include/hw/gpio/pca9552_regs.h
> index d8051cfbd6..5a6bb03396 100644
> --- a/include/hw/gpio/pca9552_regs.h
> +++ b/include/hw/gpio/pca9552_regs.h
> @@ -29,4 +29,14 @@
> */
> #define PCA9552_AUTOINC (1 << 4)
>
> +/* PCA9535 Registers (same addresses, different semantics) */
> +#define PCA9535_INPUT0 0 /* read only input register 0 */
> +#define PCA9535_INPUT1 1 /* read only input register 1 */
> +#define PCA9535_OUTPUT0 2 /* read/write output register 0 */
> +#define PCA9535_OUTPUT1 3 /* read/write output register 1 */
> +#define PCA9535_POLARITY0 4 /* read/write polarity inversion register 0 */
> +#define PCA9535_POLARITY1 5 /* read/write polarity inversion register 1 */
> +#define PCA9535_CONFIG0 6 /* read/write configuration register 0 */
> +#define PCA9535_CONFIG1 7 /* read/write configuration register 1 */
> +
> #endif
>
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