[Qemu-devel] [RFC PATCH] ati-vga: Implement DDC and EDID info from monitor

[BALATON Zoltan]

I was thinking about something like this for adding DDC/EDID support that 
several clients seem to expect to get modes other than default 640x480 but 
it's not working yet correctly. Problems:

1. Compilation fails during linking if I don't have CONFIG_BITBANG_I2C and 
CONFIG_DDC in top level default-configs/*.mak even if I add these to 
pci.mak that's included by these and is where CONFIG_ATI_VGA is defined. 
So probably only compiles for ppc-softmmu at the moment.

2. Something is read from EDID but probably not correct as guests don't 
like it. Need to debug and check if bits are wired up correctly

3. Want to use bitbang_i2c from outside hw/i2c but that's currently 
private to that dir. We had to move the struct definition to the public 
header before to avoid a warning (in commit 2b4c1125ac), maybe we need to 
move all of bitbanh_i2c.h to include/hw/i2c.h now or make this header 
public reverting the previous patch. Which one you prefer?

I may not have time to finish this before the freeze so if anyone can fix 
it feel free to take it and continue (drop me a note if you're taking it 
so we avoid duplicate work).

Signed-off-by: BALATON Zoltan <address@hidden>
---
 hw/display/ati.c     | 24 ++++++++++++++++++++++--
 hw/display/ati_int.h |  4 ++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/hw/display/ati.c b/hw/display/ati.c
index 8322f52aff..6ea845d550 100644
--- a/hw/display/ati.c
+++ b/hw/display/ati.c
@@ -24,6 +24,8 @@
 #include "qapi/error.h"
 #include "hw/hw.h"
 #include "ui/console.h"
+#include "hw/i2c/i2c-ddc.h"
+#include "../i2c/bitbang_i2c.h"
 #include "trace.h"

 #define ATI_DEBUG_HW_CURSOR 0
@@ -267,7 +269,9 @@ static uint64_t ati_mm_read(void *opaque, hwaddr addr, 
unsigned int size)
     case DAC_CNTL:
         val = s->regs.dac_cntl;
         break;
-/*    case GPIO_MONID: FIXME hook up DDC I2C here */
+    case GPIO_MONID:
+        val = s->regs.gpio_monid;
+        break;
     case PALETTE_INDEX:
         /* FIXME unaligned access */
         val = vga_ioport_read(&s->vga, VGA_PEL_IR) << 16;
@@ -501,7 +505,17 @@ static void ati_mm_write(void *opaque, hwaddr addr,
         s->regs.dac_cntl = data & 0xffffe3ff;
         s->vga.dac_8bit = !!(data & DAC_8BIT_EN);
         break;
-/*    case GPIO_MONID: FIXME hook up DDC I2C here */
+    case GPIO_MONID:
+        s->regs.gpio_monid = data & 0x000f000f;
+        if (data & BIT(2) << 16) {
+            s->regs.gpio_monid |= bitbang_i2c_set(s->bbi2c, BITBANG_I2C_SCL,
+                                                  (data & BIT(2)) != 0) << 10;
+        }
+        if (data & BIT(1) << 16) {
+            s->regs.gpio_monid |= bitbang_i2c_set(s->bbi2c, BITBANG_I2C_SDA,
+                                                  (data & BIT(1)) != 0) << 9;
+        }
+        break;
     case PALETTE_INDEX ... PALETTE_INDEX + 3:
         if (size == 4) {
             vga_ioport_write(&s->vga, VGA_PEL_IR, (data >> 16) & 0xff);
@@ -792,6 +806,12 @@ static void ati_vga_realize(PCIDevice *dev, Error **errp)
         vga->cursor_draw_line = ati_cursor_draw_line;
     }

+    /* ddc, edid */
+    s->ddc = i2c_init_bus(DEVICE(s), "ati-vga.ddc");
+    s->bbi2c = bitbang_i2c_init(s->ddc);
+    I2CDDCState *i2cddc = I2CDDC(qdev_create(BUS(s->ddc), TYPE_I2CDDC));
+    i2c_set_slave_address(I2C_SLAVE(i2cddc), 0x50);
+
     /* mmio register space */
     memory_region_init_io(&s->mm, OBJECT(s), &ati_mm_ops, s,
                           "ati.mmregs", 0x4000);
diff --git a/hw/display/ati_int.h b/hw/display/ati_int.h
index a6f3e20e63..1636f4d710 100644
--- a/hw/display/ati_int.h
+++ b/hw/display/ati_int.h
@@ -11,6 +11,7 @@

 #include "qemu/osdep.h"
 #include "hw/pci/pci.h"
+#include "hw/i2c/i2c.h"
 #include "vga_int.h"

 /*#define DEBUG_ATI*/
@@ -36,6 +37,7 @@ typedef struct ATIVGARegs {
     uint32_t crtc_gen_cntl;
     uint32_t crtc_ext_cntl;
     uint32_t dac_cntl;
+    uint32_t gpio_monid;
     uint32_t crtc_h_total_disp;
     uint32_t crtc_h_sync_strt_wid;
     uint32_t crtc_v_total_disp;
@@ -84,6 +86,8 @@ typedef struct ATIVGAState {
     uint16_t cursor_size;
     uint32_t cursor_offset;
     QEMUCursor *cursor;
+    I2CBus *ddc;
+    bitbang_i2c_interface *bbi2c;
     MemoryRegion io;
     MemoryRegion mm;
     ATIVGARegs regs;
-- 
2.13.7