versatilepb: Implement SYS_CLCD mux control register bits

On the Versatile PB, PL110 graphics adaptor only natively supports
5551 pixel format; an external mux swaps bits around to allow
RGB565 and BGR565, under the control of bits [1:0] in the SYS_CLCD
system register.

Implement these SYS_CLCD register bits, and use a gpio line to
feed them out of the system register model, across the versatilepb
board and into the pl110 so we can select the right format.

This is necessary as recent Linux versatile kernels default to
programming the CLCD and mux for 16 bit BGR rather than 16 bit RGB.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

3 files changed, 80 insertions, 11 deletions

diff --git a/hw/arm_sysctl.c b/hw/arm_sysctl.c
index fd0c8bc3d6..22c62dfebb 100644
--- a/hw/arm_sysctl.c
+++ b/hw/arm_sysctl.c
@@ -17,6 +17,8 @@
 
 typedef struct {
     SysBusDevice busdev;
+    qemu_irq pl110_mux_ctrl;
+
     uint32_t sys_id;
     uint32_t leds;
     uint16_t lockval;
@@ -30,11 +32,12 @@ typedef struct {
     uint32_t sys_cfgdata;
     uint32_t sys_cfgctrl;
     uint32_t sys_cfgstat;
+    uint32_t sys_clcd;
 } arm_sysctl_state;
 
 static const VMStateDescription vmstate_arm_sysctl = {
     .name = "realview_sysctl",
-    .version_id = 2,
+    .version_id = 3,
     .minimum_version_id = 1,
     .fields = (VMStateField[]) {
         VMSTATE_UINT32(leds, arm_sysctl_state),
@@ -48,6 +51,7 @@ static const VMStateDescription vmstate_arm_sysctl = {
         VMSTATE_UINT32_V(sys_cfgdata, arm_sysctl_state, 2),
         VMSTATE_UINT32_V(sys_cfgctrl, arm_sysctl_state, 2),
         VMSTATE_UINT32_V(sys_cfgstat, arm_sysctl_state, 2),
+        VMSTATE_UINT32_V(sys_clcd, arm_sysctl_state, 3),
         VMSTATE_END_OF_LIST()
     }
 };
@@ -78,6 +82,13 @@ static void arm_sysctl_reset(DeviceState *d)
     s->cfgdata2 = 0;
     s->flags = 0;
     s->resetlevel = 0;
+    if (board_id(s) == BOARD_ID_VEXPRESS) {
+        /* On VExpress this register will RAZ/WI */
+        s->sys_clcd = 0;
+    } else {
+        /* All others: CLCDID 0x1f, indicating VGA */
+        s->sys_clcd = 0x1f00;
+    }
 }
 
 static uint32_t arm_sysctl_read(void *opaque, target_phys_addr_t offset)
@@ -124,7 +135,7 @@ static uint32_t arm_sysctl_read(void *opaque, target_phys_addr_t offset)
     case 0x4c: /* FLASH */
         return 0;
     case 0x50: /* CLCD */
-        return 0x1000;
+        return s->sys_clcd;
     case 0x54: /* CLCDSER */
         return 0;
     case 0x58: /* BOOTCS */
@@ -232,7 +243,39 @@ static void arm_sysctl_write(void *opaque, target_phys_addr_t offset,
         /* nothing to do.  */
         break;
     case 0x4c: /* FLASH */
+        break;
     case 0x50: /* CLCD */
+        switch (board_id(s)) {
+        case BOARD_ID_PB926:
+            /* On 926 bits 13:8 are R/O, bits 1:0 control
+             * the mux that defines how to interpret the PL110
+             * graphics format, and other bits are r/w but we
+             * don't implement them to do anything.
+             */
+            s->sys_clcd &= 0x3f00;
+            s->sys_clcd |= val & ~0x3f00;
+            qemu_set_irq(s->pl110_mux_ctrl, val & 3);
+            break;
+        case BOARD_ID_EB:
+            /* The EB is the same except that there is no mux since
+             * the EB has a PL111.
+             */
+            s->sys_clcd &= 0x3f00;
+            s->sys_clcd |= val & ~0x3f00;
+            break;
+        case BOARD_ID_PBA8:
+        case BOARD_ID_PBX:
+            /* On PBA8 and PBX bit 7 is r/w and all other bits
+             * are either r/o or RAZ/WI.
+             */
+            s->sys_clcd &= (1 << 7);
+            s->sys_clcd |= val & ~(1 << 7);
+            break;
+        case BOARD_ID_VEXPRESS:
+        default:
+            /* On VExpress this register is unimplemented and will RAZ/WI */
+            break;
+        }
     case 0x54: /* CLCDSER */
     case 0x64: /* DMAPSR0 */
     case 0x68: /* DMAPSR1 */
@@ -334,7 +377,7 @@ static int arm_sysctl_init1(SysBusDevice *dev)
                                        DEVICE_NATIVE_ENDIAN);
     sysbus_init_mmio(dev, 0x1000, iomemtype);
     qdev_init_gpio_in(&s->busdev.qdev, arm_sysctl_gpio_set, 2);
-    /* ??? Save/restore.  */
+    qdev_init_gpio_out(&s->busdev.qdev, &s->pl110_mux_ctrl, 1);
     return 0;
 }
 
diff --git a/hw/pl110.c b/hw/pl110.c
index 384eba2198..4ac710a6ec 100644
--- a/hw/pl110.c
+++ b/hw/pl110.c
@@ -53,6 +53,7 @@ typedef struct {
     int rows;
     enum pl110_bppmode bpp;
     int invalidate;
+    uint32_t mux_ctrl;
     uint32_t pallette[256];
     uint32_t raw_pallette[128];
     qemu_irq irq;
@@ -60,7 +61,7 @@ typedef struct {
 
 static const VMStateDescription vmstate_pl110 = {
     .name = "pl110",
-    .version_id = 1,
+    .version_id = 2,
     .minimum_version_id = 1,
     .fields = (VMStateField[]) {
         VMSTATE_INT32(version, pl110_state),
@@ -76,6 +77,7 @@ static const VMStateDescription vmstate_pl110 = {
         VMSTATE_INT32(invalidate, pl110_state),
         VMSTATE_UINT32_ARRAY(pallette, pl110_state, 256),
         VMSTATE_UINT32_ARRAY(raw_pallette, pl110_state, 128),
+        VMSTATE_UINT32_V(mux_ctrl, pl110_state, 2),
         VMSTATE_END_OF_LIST()
     }
 };
@@ -173,16 +175,26 @@ static void pl110_update_display(void *opaque)
          * mux which allows bits to be reshuffled to give
          * 565 format. The mux is typically controlled by
          * an external system register.
-         * This should be controlled by a GPIO input pin
+         * This is controlled by a GPIO input pin
          * so boards can wire it up to their register.
-         * For now, force 16 bit to be 565, to match
-         * previous QEMU PL110 model behaviour.
          *
          * The PL111 straightforwardly implements both
          * 5551 and 565 under control of the bpp field
          * in the LCDControl register.
          */
-        bpp_offset += (BPP_16_565 - BPP_16);
+        switch (s->mux_ctrl) {
+        case 3: /* 565 BGR */
+            bpp_offset = (BPP_16_565 - BPP_16);
+            break;
+        case 1: /* 5551 */
+            break;
+        case 0: /* 888; also if we have loaded vmstate from an old version */
+        case 2: /* 565 RGB */
+        default:
+            /* treat as 565 but honour BGR bit */
+            bpp_offset += (BPP_16_565 - BPP_16);
+            break;
+        }
     }
 
     if (s->cr & PL110_CR_BEBO)
@@ -416,6 +428,12 @@ static CPUWriteMemoryFunc * const pl110_writefn[] = {
    pl110_write
 };
 
+static void pl110_mux_ctrl_set(void *opaque, int line, int level)
+{
+    pl110_state *s = (pl110_state *)opaque;
+    s->mux_ctrl = level;
+}
+
 static int pl110_init(SysBusDevice *dev)
 {
     pl110_state *s = FROM_SYSBUS(pl110_state, dev);
@@ -426,6 +444,7 @@ static int pl110_init(SysBusDevice *dev)
                                        DEVICE_NATIVE_ENDIAN);
     sysbus_init_mmio(dev, 0x1000, iomemtype);
     sysbus_init_irq(dev, &s->irq);
+    qdev_init_gpio_in(&s->busdev.qdev, pl110_mux_ctrl_set, 1);
     s->ds = graphic_console_init(pl110_update_display,
                                  pl110_invalidate_display,
                                  NULL, NULL, s);
diff --git a/hw/versatilepb.c b/hw/versatilepb.c
index 147fe29b61..49f8f5fc56 100644
--- a/hw/versatilepb.c
+++ b/hw/versatilepb.c
@@ -180,7 +180,7 @@ static void versatile_init(ram_addr_t ram_size,
     qemu_irq *cpu_pic;
     qemu_irq pic[32];
     qemu_irq sic[32];
-    DeviceState *dev;
+    DeviceState *dev, *sysctl;
     PCIBus *pci_bus;
     NICInfo *nd;
     int n;
@@ -198,7 +198,12 @@ static void versatile_init(ram_addr_t ram_size,
     /* SDRAM at address zero.  */
     cpu_register_physical_memory(0, ram_size, ram_offset | IO_MEM_RAM);
 
-    arm_sysctl_init(0x10000000, 0x41007004, 0x02000000);
+    sysctl = qdev_create(NULL, "realview_sysctl");
+    qdev_prop_set_uint32(sysctl, "sys_id", 0x41007004);
+    qdev_init_nofail(sysctl);
+    qdev_prop_set_uint32(sysctl, "proc_id", 0x02000000);
+    sysbus_mmio_map(sysbus_from_qdev(sysctl), 0, 0x10000000);
+
     cpu_pic = arm_pic_init_cpu(env);
     dev = sysbus_create_varargs("pl190", 0x10140000,
                                 cpu_pic[0], cpu_pic[1], NULL);
@@ -250,7 +255,9 @@ static void versatile_init(ram_addr_t ram_size,
 
     /* The versatile/PB actually has a modified Color LCD controller
        that includes hardware cursor support from the PL111.  */
-    sysbus_create_simple("pl110_versatile", 0x10120000, pic[16]);
+    dev = sysbus_create_simple("pl110_versatile", 0x10120000, pic[16]);
+    /* Wire up the mux control signals from the SYS_CLCD register */
+    qdev_connect_gpio_out(sysctl, 0, qdev_get_gpio_in(dev, 0));
 
     sysbus_create_varargs("pl181", 0x10005000, sic[22], sic[1], NULL);
     sysbus_create_varargs("pl181", 0x1000b000, sic[23], sic[2], NULL);