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>

6 files changed, 242 insertions, 0 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index ef6f5c7399..7e442b5247 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1967,6 +1967,12 @@ F: docs/specs/vmgenid.txt
 F: tests/qtest/vmgenid-test.c
 F: stubs/vmgenid.c
 
+LED
+M: Philippe Mathieu-Daudé <f4bug@amsat.org>
+S: Maintained
+F: include/hw/misc/led.h
+F: hw/misc/led.c
+
 Unimplemented device
 M: Peter Maydell <peter.maydell@linaro.org>
 R: Philippe Mathieu-Daudé <f4bug@amsat.org>
diff --git a/hw/misc/Kconfig b/hw/misc/Kconfig
index 3185456110..e4d059591a 100644
--- a/hw/misc/Kconfig
+++ b/hw/misc/Kconfig
@@ -126,6 +126,9 @@ config AUX
 config UNIMP
     bool
 
+config LED
+    bool
+
 config MAC_VIA
     bool
     select MOS6522
diff --git a/hw/misc/led.c b/hw/misc/led.c
new file mode 100644
index 0000000000..1e2f49c571
--- /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);
+}
diff --git a/hw/misc/meson.build b/hw/misc/meson.build
index 793d45b1dc..aa8ec3bca9 100644
--- a/hw/misc/meson.build
+++ b/hw/misc/meson.build
@@ -11,6 +11,7 @@ softmmu_ss.add(when: 'CONFIG_TMP105', if_true: files('tmp105.c'))
 softmmu_ss.add(when: 'CONFIG_TMP421', if_true: files('tmp421.c'))
 softmmu_ss.add(when: 'CONFIG_UNIMP', if_true: files('unimp.c'))
 softmmu_ss.add(when: 'CONFIG_EMPTY_SLOT', if_true: files('empty_slot.c'))
+softmmu_ss.add(when: 'CONFIG_LED', if_true: files('led.c'))
 
 # ARM devices
 softmmu_ss.add(when: 'CONFIG_PL310', if_true: files('arm_l2x0.c'))
diff --git a/hw/misc/trace-events b/hw/misc/trace-events
index 6054f9adf3..2b6310dbe4 100644
--- a/hw/misc/trace-events
+++ b/hw/misc/trace-events
@@ -223,6 +223,9 @@ via1_adb_poll(uint8_t data, const char *vadbint, int status, int index, int size
 grlib_ahb_pnp_read(uint64_t addr, uint32_t value) "AHB PnP read addr:0x%03"PRIx64" data:0x%08x"
 grlib_apb_pnp_read(uint64_t addr, uint32_t value) "APB PnP read addr:0x%03"PRIx64" data:0x%08x"
 
+# led.c
+led_set_intensity(const char *color, const char *desc, uint8_t intensity_percent) "LED desc:'%s' color:%s intensity: %u%%"
+
 # pca9552.c
 pca955x_gpio_status(const char *description, const char *buf) "%s GPIOs 0-15 [%s]"
 pca955x_gpio_change(const char *description, unsigned id, unsigned prev_state, unsigned current_state) "%s GPIO id:%u status: %u -> %u"
diff --git a/include/hw/misc/led.h b/include/hw/misc/led.h
new file mode 100644
index 0000000000..286d37c75c
--- /dev/null
+++ b/include/hw/misc/led.h
@@ -0,0 +1,87 @@
+/*
+ * QEMU single LED device
+ *
+ * Copyright (C) 2020 Philippe Mathieu-Daudé <f4bug@amsat.org>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#ifndef HW_MISC_LED_H
+#define HW_MISC_LED_H
+
+#include "qom/object.h"
+
+#define TYPE_LED "led"
+
+/**
+ * LEDColor: Color of a LED
+ *
+ * This set is restricted to physically available LED colors.
+ *
+ * LED colors from 'Table 1. Product performance of LUXEON Rebel Color
+ * Line' of the 'DS68 LUXEON Rebel Color Line' datasheet available at:
+ * https://www.lumileds.com/products/color-leds/luxeon-rebel-color/
+ */
+typedef enum {          /* Coarse wavelength range */
+    LED_COLOR_VIOLET,   /* 425 nm */
+    LED_COLOR_BLUE,     /* 475 nm */
+    LED_COLOR_CYAN,     /* 500 nm */
+    LED_COLOR_GREEN,    /* 535 nm */
+    LED_COLOR_AMBER,    /* 590 nm */
+    LED_COLOR_ORANGE,   /* 615 nm */
+    LED_COLOR_RED,      /* 630 nm */
+} LEDColor;
+
+struct LEDState {
+    /* Private */
+    DeviceState parent_obj;
+    /* Public */
+
+    uint8_t intensity_percent;
+
+    /* Properties */
+    char *description;
+    char *color;
+};
+typedef struct LEDState LEDState;
+DECLARE_INSTANCE_CHECKER(LEDState, LED, TYPE_LED)
+
+/**
+ * led_set_intensity: Set the intensity of a LED device
+ * @s: the LED object
+ * @intensity_percent: intensity as percentage in range 0 to 100.
+ */
+void led_set_intensity(LEDState *s, unsigned intensity_percent);
+
+/**
+ * led_get_intensity:
+ * @s: the LED object
+ *
+ * Returns: The LED intensity as percentage in range 0 to 100.
+ */
+unsigned led_get_intensity(LEDState *s);
+
+/**
+ * led_set_state: Set the state of a LED device
+ * @s: the LED object
+ * @is_emitting: boolean indicating whether the LED is emitting
+ *
+ * This utility is meant for LED connected to GPIO.
+ */
+void led_set_state(LEDState *s, bool is_emitting);
+
+/**
+ * led_create_simple: Create and realize a LED device
+ * @parentobj: the parent object
+ * @color: color of the LED
+ * @description: description of the LED (optional)
+ *
+ * Create the device state structure, initialize it, and
+ * drop the reference to it (the device is realized).
+ *
+ * Returns: The newly allocated and instantiated LED object.
+ */
+LEDState *led_create_simple(Object *parentobj,
+                            LEDColor color,
+                            const char *description);
+
+#endif /* HW_MISC_LED_H */