This implements rudimentary support for interrupt generation on the
PL110. I am working on a new DRI/KMS driver for Linux and since that
uses the blanking interrupt, we need something to fire here. Without
any interrupt support Linux waits for a while and then gives ugly
messages about the vblank not working in the console (it does not
hang perpetually or anything though, DRI is pretty forgiving).

I solved it for now by setting up a timer to fire at 60Hz and pull
the interrupts for "vertical compare" and "next memory base"
at this interval. This works fine and fires roughly the same number
of IRQs on QEMU as on the hardware and leaves the console clean
and nice.

People who want to create more accurate emulation can probably work
on top of this if need be. It is certainly closer to the hardware
behaviour than what we have today anyway.

Cc: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
 hw/display/pl110.c | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/hw/display/pl110.c b/hw/display/pl110.c
index 8c7dcc6f0a69..777bb3f44503 100644
--- a/hw/display/pl110.c
+++ b/hw/display/pl110.c
@@ -12,6 +12,7 @@
 #include "ui/console.h"
 #include "framebuffer.h"
 #include "ui/pixel_ops.h"
+#include "qemu/timer.h"
 #include "qemu/log.h"
 
 #define PL110_CR_EN   0x001
@@ -19,6 +20,8 @@
 #define PL110_CR_BEBO 0x200
 #define PL110_CR_BEPO 0x400
 #define PL110_CR_PWR  0x800
+#define PL110_IE_NB   0x004
+#define PL110_IE_VC   0x008
 
 enum pl110_bppmode
 {
@@ -50,6 +53,7 @@ typedef struct PL110State {
     MemoryRegion iomem;
     MemoryRegionSection fbsection;
     QemuConsole *con;
+    QEMUTimer *vblank_timer;
 
     int version;
     uint32_t timing[4];
@@ -320,7 +324,23 @@ static void pl110_resize(PL110State *s, int width, int height)
 /* Update interrupts.  */
 static void pl110_update(PL110State *s)
 {
-  /* TODO: Implement interrupts.  */
+    /* Raise IRQ if enabled and any status bit is 1 */
+    if (s->int_status & s->int_mask) {
+        qemu_irq_raise(s->irq);
+    } else {
+        qemu_irq_lower(s->irq);
+    }
+}
+
+static void pl110_vblank_interrupt(void *opaque)
+{
+    PL110State *s = opaque;
+
+    /* Fire the vertical compare and next base IRQs and re-arm */
+    s->int_status |= (PL110_IE_NB | PL110_IE_VC);
+    timer_mod(s->vblank_timer,
+              qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + NANOSECONDS_PER_SECOND / 60);
+    pl110_update(s);
 }
 
 static uint64_t pl110_read(void *opaque, hwaddr offset,
@@ -429,6 +449,10 @@ static void pl110_write(void *opaque, hwaddr offset,
         s->bpp = (val >> 1) & 7;
         if (pl110_enabled(s)) {
             qemu_console_resize(s->con, s->cols, s->rows);
+            timer_mod(s->vblank_timer,
+                      qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + NANOSECONDS_PER_SECOND / 60);
+        } else {
+            timer_del(s->vblank_timer);
         }
         break;
     case 10: /* LCDICR */
@@ -474,6 +498,7 @@ static void pl110_realize(DeviceState *dev, Error **errp)
     memory_region_init_io(&s->iomem, OBJECT(s), &pl110_ops, s, "pl110", 0x1000);
     sysbus_init_mmio(sbd, &s->iomem);
     sysbus_init_irq(sbd, &s->irq);
+    s->vblank_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, pl110_vblank_interrupt, s);
     qdev_init_gpio_in(dev, pl110_mux_ctrl_set, 1);
     s->con = graphic_console_init(dev, 0, &pl110_gfx_ops, s);
 }
-- 
2.14.3

Hi,

This series seems to have some coding style problems. See output below for
more information:

Type: series
Message-id: 20180123225654.5764-1-linus.walleij@linaro.org
Subject: [Qemu-devel] [PATCH] pl110: Implement vertical compare/next base interrupts

=== TEST SCRIPT BEGIN ===
#!/bin/bash

BASE=base
n=1
total=$(git log --oneline $BASE.. | wc -l)
failed=0

git config --local diff.renamelimit 0
git config --local diff.renames True

commits="$(git log --format=%H --reverse $BASE..)"
for c in $commits; do
    echo "Checking PATCH $n/$total: $(git log -n 1 --format=%s $c)..."
    if ! git show $c --format=email | ./scripts/checkpatch.pl --mailback -; then
        failed=1
        echo
    fi
    n=$((n+1))
done

exit $failed
=== TEST SCRIPT END ===

Updating 3c8cf5a9c21ff8782164d1def7f44bd888713384
From https://github.com/patchew-project/qemu
 * [new tag]               patchew/20180123225654.5764-1-linus.walleij@linaro.org -> patchew/20180123225654.5764-1-linus.walleij@linaro.org
Switched to a new branch 'test'
2512b151b6 pl110: Implement vertical compare/next base interrupts

=== OUTPUT BEGIN ===
Checking PATCH 1/1: pl110: Implement vertical compare/next base interrupts...
WARNING: line over 80 characters
#76: FILE: hw/display/pl110.c:342:
+              qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + NANOSECONDS_PER_SECOND / 60);

ERROR: line over 90 characters
#86: FILE: hw/display/pl110.c:453:
+                      qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + NANOSECONDS_PER_SECOND / 60);

WARNING: line over 80 characters
#96: FILE: hw/display/pl110.c:501:
+    s->vblank_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, pl110_vblank_interrupt, s);

total: 1 errors, 2 warnings, 63 lines checked

Your patch has style problems, please review.  If any of these errors
are false positives report them to the maintainer, see
CHECKPATCH in MAINTAINERS.

=== OUTPUT END ===

Test command exited with code: 1


---
Email generated automatically by Patchew [http://patchew.org/].
Please send your feedback to patchew-devel@freelists.org

On 23 January 2018 at 22:56, Linus Walleij <linus.walleij@linaro.org> wrote:
> This implements rudimentary support for interrupt generation on the
> PL110. I am working on a new DRI/KMS driver for Linux and since that
> uses the blanking interrupt, we need something to fire here. Without
> any interrupt support Linux waits for a while and then gives ugly
> messages about the vblank not working in the console (it does not
> hang perpetually or anything though, DRI is pretty forgiving).
>
> I solved it for now by setting up a timer to fire at 60Hz and pull
> the interrupts for "vertical compare" and "next memory base"
> at this interval. This works fine and fires roughly the same number
> of IRQs on QEMU as on the hardware and leaves the console clean
> and nice.
>
> People who want to create more accurate emulation can probably work
> on top of this if need be. It is certainly closer to the hardware
> behaviour than what we have today anyway.

Yeah, I think that "fire every 60Hz" is good enough for now.

Applied to target-arm.next (with the long lines checkpatch
complains about folded).

thanks
-- PMM