[Qemu-devel] [PATCH] Realview/Versatile: Export LED state

[Wolfgang Mauerer]

The configuration register for the onboard LEDs is
emulated, but the state is not exported, which makes
the feature not particularly useful. Create a character
device to make status changes accessible to the host.

For example, use the command line argument

-chardev socket,id=leds,host=localhost,port=12345,server,nowait

to observe status changes via a socket.

Signed-off-by: Wolfgang Mauerer <address@hidden>
---
 hw/arm_sysctl.c |   24 ++++++++++++++++++++++++
 1 files changed, 24 insertions(+), 0 deletions(-)

diff --git a/hw/arm_sysctl.c b/hw/arm_sysctl.c
index b733617..7cb8559 100644
--- a/hw/arm_sysctl.c
+++ b/hw/arm_sysctl.c
@@ -19,6 +19,7 @@ typedef struct {
     SysBusDevice busdev;
     MemoryRegion iomem;
     qemu_irq pl110_mux_ctrl;
+    CharDriverState *display;
 
     uint32_t sys_id;
     uint32_t leds;
@@ -92,6 +93,24 @@ static void arm_sysctl_reset(DeviceState *d)
     }
 }
 
+static void notify_led_change(CharDriverState *chr, uint32_t old, uint32_t new)
+{
+    uint32_t changed;
+    unsigned int i;
+
+    if (chr == NULL) {
+        return;
+    }
+
+    changed = old ^ new;
+    for (i = 0; i < 8; i++) {
+        if (changed & (1 << i)) {
+            qemu_chr_fe_printf(chr, "%u:%s\r\n", i,
+                               new & (1 << i) ? "on" : "off");
+        }
+    }
+}
+
 static uint64_t arm_sysctl_read(void *opaque, hwaddr offset,
                                 unsigned size)
 {
@@ -198,6 +217,7 @@ static void arm_sysctl_write(void *opaque, hwaddr offset,
 
     switch (offset) {
     case 0x08: /* LED */
+        notify_led_change(s->display, s->leds, (uint32_t)val);
         s->leds = val;
     case 0x0c: /* OSC0 */
     case 0x10: /* OSC1 */
@@ -386,6 +406,10 @@ static int arm_sysctl_init(SysBusDevice *dev)
 {
     arm_sysctl_state *s = FROM_SYSBUS(arm_sysctl_state, dev);
 
+    s->display = qemu_chr_new("leds0", "chardev:leds", NULL);
+    if (s->display) {
+        qemu_chr_fe_printf(s->display, "8 LEDs available\r\n");
+    }
     memory_region_init_io(&s->iomem, &arm_sysctl_ops, s, "arm-sysctl", 0x1000);
     sysbus_init_mmio(dev, &s->iomem);
     qdev_init_gpio_in(&s->busdev.qdev, arm_sysctl_gpio_set, 2);
-- 
1.7.1