4 files changed, 117 insertions, 0 deletions
diff --git a/include/hw/misc/led.h b/include/hw/misc/led.h
new file mode 100644
index 0000000000..aa359b87c2
--- /dev/null
+++ b/include/hw/misc/led.h
@@ -0,0 +1,97 @@
+/*
+ * 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"
+#include "hw/qdev-core.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;
+    qemu_irq irq;
+
+    /* Properties */
+    char *description;
+    char *color;
+    /*
+     * Determines whether a GPIO is using a positive (active-high)
+     * logic (when used with GPIO, the intensity at reset is related
+     * to the GPIO polarity).
+     */
+    bool gpio_active_high;
+};
+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
+ * @gpio_polarity: GPIO polarity
+ * @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,
+                            GpioPolarity gpio_polarity,
+                            LEDColor color,
+                            const char *description);
+
+#endif /* HW_MISC_LED_H */
diff --git a/include/hw/misc/mps2-fpgaio.h b/include/hw/misc/mps2-fpgaio.h
index 80f9227aa6..a010fdb2b6 100644
--- a/include/hw/misc/mps2-fpgaio.h
+++ b/include/hw/misc/mps2-fpgaio.h
@@ -22,6 +22,7 @@
 #define MPS2_FPGAIO_H
 
 #include "hw/sysbus.h"
+#include "hw/misc/led.h"
 #include "qom/object.h"
 
 #define TYPE_MPS2_FPGAIO "mps2-fpgaio"
@@ -33,6 +34,7 @@ struct MPS2FPGAIO {
 
     /*< public >*/
     MemoryRegion iomem;
+    LEDState *led[2];
 
     uint32_t led0;
     uint32_t prescale;
diff --git a/include/hw/misc/mps2-scc.h b/include/hw/misc/mps2-scc.h
index e922b3c8e0..f65d873203 100644
--- a/include/hw/misc/mps2-scc.h
+++ b/include/hw/misc/mps2-scc.h
@@ -13,6 +13,7 @@
 #define MPS2_SCC_H
 
 #include "hw/sysbus.h"
+#include "hw/misc/led.h"
 #include "qom/object.h"
 
 #define TYPE_MPS2_SCC "mps2-scc"
@@ -26,6 +27,7 @@ struct MPS2SCC {
 
     /*< public >*/
     MemoryRegion iomem;
+    LEDState *led[8];
 
     uint32_t cfg0;
     uint32_t cfg1;
diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index 868973319e..a653295d6f 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -444,6 +444,22 @@ void qdev_machine_creation_done(void);
 bool qdev_machine_modified(void);
 
 /**
+ * GpioPolarity: Polarity of a GPIO line
+ *
+ * GPIO lines use either positive (active-high) logic,
+ * or negative (active-low) logic.
+ *
+ * In active-high logic (%GPIO_POLARITY_ACTIVE_HIGH), a pin is
+ * active when the voltage on the pin is high (relative to ground);
+ * whereas in active-low logic (%GPIO_POLARITY_ACTIVE_LOW), a pin
+ * is active when the voltage on the pin is low (or grounded).
+ */
+typedef enum {
+    GPIO_POLARITY_ACTIVE_LOW,
+    GPIO_POLARITY_ACTIVE_HIGH
+} GpioPolarity;
+
+/**
  * qdev_get_gpio_in: Get one of a device's anonymous input GPIO lines
  * @dev: Device whose GPIO we want
  * @n: Number of the anonymous GPIO line (which must be in range)