hw/misc/led: Add a LED device

Add a LED device which can be connected to a GPIO output.
They can also be dimmed with PWM devices. For now we do
not implement the dimmed mode, but in preparation of a
future implementation, we start using the LED intensity.

LEDs are limited to a fixed set of colors.

Reviewed-by: Luc Michel <luc.michel@greensocs.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20200912134041.946260-2-f4bug@amsat.org>

1 files changed, 142 insertions, 0 deletions

diff --git a/hw/misc/led.c b/hw/misc/led.c
new file mode 100644
index 0000000..1e2f49c
--- /dev/null
+++ b/hw/misc/led.c
@@ -0,0 +1,142 @@
+/*
+ * QEMU single LED device
+ *
+ * Copyright (C) 2020 Philippe Mathieu-Daudé <f4bug@amsat.org>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "migration/vmstate.h"
+#include "hw/qdev-properties.h"
+#include "hw/misc/led.h"
+#include "trace.h"
+
+#define LED_INTENSITY_PERCENT_MAX   100
+
+static const char * const led_color_name[] = {
+    [LED_COLOR_VIOLET]  = "violet",
+    [LED_COLOR_BLUE]    = "blue",
+    [LED_COLOR_CYAN]    = "cyan",
+    [LED_COLOR_GREEN]   = "green",
+    [LED_COLOR_AMBER]   = "amber",
+    [LED_COLOR_ORANGE]  = "orange",
+    [LED_COLOR_RED]     = "red",
+};
+
+static bool led_color_name_is_valid(const char *color_name)
+{
+    for (size_t i = 0; i < ARRAY_SIZE(led_color_name); i++) {
+        if (strcmp(color_name, led_color_name[i]) == 0) {
+            return true;
+        }
+    }
+    return false;
+}
+
+void led_set_intensity(LEDState *s, unsigned intensity_percent)
+{
+    if (intensity_percent > LED_INTENSITY_PERCENT_MAX) {
+        intensity_percent = LED_INTENSITY_PERCENT_MAX;
+    }
+    trace_led_set_intensity(s->description, s->color, intensity_percent);
+    s->intensity_percent = intensity_percent;
+}
+
+unsigned led_get_intensity(LEDState *s)
+{
+    return s->intensity_percent;
+}
+
+void led_set_state(LEDState *s, bool is_emitting)
+{
+    led_set_intensity(s, is_emitting ? LED_INTENSITY_PERCENT_MAX : 0);
+}
+
+static void led_reset(DeviceState *dev)
+{
+    LEDState *s = LED(dev);
+
+    led_set_state(s, false);
+}
+
+static const VMStateDescription vmstate_led = {
+    .name = TYPE_LED,
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT8(intensity_percent, LEDState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void led_realize(DeviceState *dev, Error **errp)
+{
+    LEDState *s = LED(dev);
+
+    if (s->color == NULL) {
+        error_setg(errp, "property 'color' not specified");
+        return;
+    } else if (!led_color_name_is_valid(s->color)) {
+        error_setg(errp, "property 'color' invalid or not supported");
+        return;
+    }
+    if (s->description == NULL) {
+        s->description = g_strdup("n/a");
+    }
+}
+
+static Property led_properties[] = {
+    DEFINE_PROP_STRING("color", LEDState, color),
+    DEFINE_PROP_STRING("description", LEDState, description),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void led_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->desc = "LED";
+    dc->vmsd = &vmstate_led;
+    dc->reset = led_reset;
+    dc->realize = led_realize;
+    set_bit(DEVICE_CATEGORY_DISPLAY, dc->categories);
+    device_class_set_props(dc, led_properties);
+}
+
+static const TypeInfo led_info = {
+    .name = TYPE_LED,
+    .parent = TYPE_DEVICE,
+    .instance_size = sizeof(LEDState),
+    .class_init = led_class_init
+};
+
+static void led_register_types(void)
+{
+    type_register_static(&led_info);
+}
+
+type_init(led_register_types)
+
+LEDState *led_create_simple(Object *parentobj,
+                            LEDColor color,
+                            const char *description)
+{
+    g_autofree char *name = NULL;
+    DeviceState *dev;
+
+    dev = qdev_new(TYPE_LED);
+    qdev_prop_set_string(dev, "color", led_color_name[color]);
+    if (!description) {
+        static unsigned undescribed_led_id;
+        name = g_strdup_printf("undescribed-led-#%u", undescribed_led_id++);
+    } else {
+        qdev_prop_set_string(dev, "description", description);
+        name = g_ascii_strdown(description, -1);
+        name = g_strdelimit(name, " #", '-');
+    }
+    object_property_add_child(parentobj, name, OBJECT(dev));
+    qdev_realize_and_unref(dev, NULL, &error_fatal);
+
+    return LED(dev);
+}