hw/gpio: pca9552: expose GPIO pins as pin%d QOM properties
The PCA9552 exposes its LED channels as led%d QOM string properties, but the GPIO variants (PCA9535/PCA9555) inherited the same led%d interface, which drives the LED selector registers and is meaningless for a plain I/O expander. Add pin%d string properties ("low"/"high") for the GPIO variants, mirroring the standalone pca9555 model: - reading returns the raw pin logic level from the INPUT register; - writing drives the external input level, but only for pins the guest has configured as inputs (writes to output pins are ignored with a LOG_UNIMP message). The LED variant keeps its led%d properties. Signed-off-by: Emmanuel Blot <emmanuel.blot@free.fr> Reviewed-by: Glenn Miles <milesg@linux.ibm.com> Link: https://lore.kernel.org/qemu-devel/20260709-catalina-upgrade-v1-9-814575bc076b@free.fr Signed-off-by: Cédric Le Goater <clg@redhat.com>
Emmanuel Blot committed
Jul 9, 2026 at 17:23 UTC
a11babc63217a5e3e8a9a7350654e35755f6ad11
1 file changed
+86
-5
hw/gpio/pca9552.c
+86
-5
@@ -68,6 +68,7 @@ struct PCA955xClass {
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#define PCA9552_PIN_HIZ 0x1
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static const char *led_state[] = {"on", "off", "pwm0", "pwm1"};
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+static const char *pin_state[] = {"low", "high"};
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static uint8_t pca955x_pin_get_config(PCA955xState *s, int pin)
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{
@@ -428,6 +429,79 @@ static void pca955x_set_led(Object *obj, Visitor *v, const char *name,
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pca955x_write(s, reg, val);
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}
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+static void pca955x_set_ext_state(PCA955xState *s, int pin, int level);
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+
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+static void pca955x_get_pin(Object *obj, Visitor *v, const char *name,
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+ void *opaque, Error **errp)
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+{
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+ PCA955xClass *k = PCA955X_GET_CLASS(obj);
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+ PCA955xState *s = PCA955X(obj);
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+ int pin, rc;
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+ uint8_t input_reg, state;
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+
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+ rc = sscanf(name, "pin%2d", &pin);
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+ if (rc != 1) {
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+ error_setg(errp, "%s: error reading %s", __func__, name);
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+ return;
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+ }
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+ if (pin < 0 || pin >= k->pin_count) {
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+ error_setg(errp, "%s invalid pin %s", __func__, name);
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+ return;
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+ }
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+
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+ /*
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+ * Report the raw pin logic level; polarity inversion is a read-time
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+ * transform applied to the INPUT register, not to the pin state itself.
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+ */
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+ input_reg = PCA9535_INPUT0 + (pin / 8);
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+ state = (s->regs[input_reg] >> (pin % 8)) & 0x1;
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+ visit_type_str(v, name, (char **)&pin_state[state], errp);
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+}
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+
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+static void pca955x_set_pin(Object *obj, Visitor *v, const char *name,
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+ void *opaque, Error **errp)
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+{
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+ PCA955xClass *k = PCA955X_GET_CLASS(obj);
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+ PCA955xState *s = PCA955X(obj);
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+ int pin, rc;
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+ uint8_t state, config_reg;
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+ g_autofree char *state_str = NULL;
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+
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+ if (!visit_type_str(v, name, &state_str, errp)) {
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+ return;
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+ }
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+ rc = sscanf(name, "pin%2d", &pin);
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+ if (rc != 1) {
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+ error_setg(errp, "%s: error reading %s", __func__, name);
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+ return;
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+ }
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+ if (pin < 0 || pin >= k->pin_count) {
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+ error_setg(errp, "%s invalid pin %s", __func__, name);
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+ return;
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+ }
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+
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+ for (state = 0; state < ARRAY_SIZE(pin_state); state++) {
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+ if (!strcmp(state_str, pin_state[state])) {
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+ break;
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+ }
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+ }
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+ if (state >= ARRAY_SIZE(pin_state)) {
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+ error_setg(errp, "%s invalid pin state %s", __func__, state_str);
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+ return;
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+ }
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+
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+ /* Only input-configured pins can be driven by an external device. */
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+ config_reg = PCA9535_CONFIG0 + (pin / 8);
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+ if (!((s->regs[config_reg] >> (pin % 8)) & 0x1)) {
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+ qemu_log_mask(LOG_UNIMP,
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+ "%s: pin %d is configured as output, ignoring set\n",
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+ s->description, pin);
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+ return;
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+ }
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+
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+ pca955x_set_ext_state(s, pin, state != PCA9552_PIN_LOW);
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+}
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+
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static const VMStateDescription pca9552_vmstate = {
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.name = "PCA9552",
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.version_id = 0,
@@ -485,15 +559,22 @@ static void pca9535_reset_hold(Object *obj, ResetType type)
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static void pca955x_initfn(Object *obj)
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{
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PCA955xClass *k = PCA955X_GET_CLASS(obj);
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- int led;
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assert(k->pin_count <= PCA955X_PIN_COUNT_MAX);
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- for (led = 0; led < k->pin_count; led++) {
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+ for (int ix = 0; ix < k->pin_count; ix++) {
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char *name;
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- name = g_strdup_printf("led%d", led);
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- object_property_add(obj, name, "bool", pca955x_get_led, pca955x_set_led,
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- NULL, NULL);
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+ if (k->has_led_support) {
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+ /* LED variant: expose the LED selector state as led%d. */
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+ name = g_strdup_printf("led%d", ix);
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+ object_property_add(obj, name, "bool",
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+ pca955x_get_led, pca955x_set_led, NULL, NULL);
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+ } else {
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+ /* GPIO variant: expose the pin logic level as pin%d. */
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+ name = g_strdup_printf("pin%d", ix);
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+ object_property_add(obj, name, "str",
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+ pca955x_get_pin, pca955x_set_pin, NULL, NULL);
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+ }
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g_free(name);
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}
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}