hw/misc/led: Allow connecting from GPIO output

Some devices expose GPIO lines.

Add a GPIO qdev input to our LED device, so we can
connect a GPIO output using qdev_connect_gpio_out().

When used with GPIOs, the intensity can only be either
minium or maximum. This depends of the polarity of the
GPIO (which can be inverted).
Declare the GpioPolarity type to model the polarity.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Luc Michel <luc.michel@greensocs.com>
Message-Id: <20200912134041.946260-3-f4bug@amsat.org>

1 files changed, 16 insertions, 1 deletions

diff --git a/hw/misc/led.c b/hw/misc/led.c
index 1e2f49c571..c5fa09a613 100644
--- a/hw/misc/led.c
+++ b/hw/misc/led.c
@@ -10,6 +10,7 @@
 #include "migration/vmstate.h"
 #include "hw/qdev-properties.h"
 #include "hw/misc/led.h"
+#include "hw/irq.h"
 #include "trace.h"
 
 #define LED_INTENSITY_PERCENT_MAX   100
@@ -53,11 +54,19 @@ void led_set_state(LEDState *s, bool is_emitting)
     led_set_intensity(s, is_emitting ? LED_INTENSITY_PERCENT_MAX : 0);
 }
 
+static void led_set_state_gpio_handler(void *opaque, int line, int new_state)
+{
+    LEDState *s = LED(opaque);
+
+    assert(line == 0);
+    led_set_state(s, !!new_state != s->gpio_active_high);
+}
+
 static void led_reset(DeviceState *dev)
 {
     LEDState *s = LED(dev);
 
-    led_set_state(s, false);
+    led_set_state(s, s->gpio_active_high);
 }
 
 static const VMStateDescription vmstate_led = {
@@ -84,11 +93,14 @@ static void led_realize(DeviceState *dev, Error **errp)
     if (s->description == NULL) {
         s->description = g_strdup("n/a");
     }
+
+    qdev_init_gpio_in(DEVICE(s), led_set_state_gpio_handler, 1);
 }
 
 static Property led_properties[] = {
     DEFINE_PROP_STRING("color", LEDState, color),
     DEFINE_PROP_STRING("description", LEDState, description),
+    DEFINE_PROP_BOOL("gpio-active-high", LEDState, gpio_active_high, true),
     DEFINE_PROP_END_OF_LIST(),
 };
 
@@ -119,6 +131,7 @@ static void led_register_types(void)
 type_init(led_register_types)
 
 LEDState *led_create_simple(Object *parentobj,
+                            GpioPolarity gpio_polarity,
                             LEDColor color,
                             const char *description)
 {
@@ -126,6 +139,8 @@ LEDState *led_create_simple(Object *parentobj,
     DeviceState *dev;
 
     dev = qdev_new(TYPE_LED);
+    qdev_prop_set_bit(dev, "gpio-active-high",
+                      gpio_polarity == GPIO_POLARITY_ACTIVE_HIGH);
     qdev_prop_set_string(dev, "color", led_color_name[color]);
     if (!description) {
         static unsigned undescribed_led_id;