x86: qemu: Turn on legacy segments decode

By default the legacy segments C/D/E/F do not decode to system RAM.
Turn on the decode via Programmable Attribute Map (PAM) registers
so that we can write configuration tables in the F segment.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>

diff --git a/arch/x86/cpu/qemu/pci.c b/arch/x86/cpu/qemu/pci.c
index ac9c056e2be5b9e6a941baaf3629d73ffa79bdf2..2f4ba1785db408ce8b06f77860fa695cb67ed6a2 100644 (file)
--- a/arch/x86/cpu/qemu/pci.c
+++ b/arch/x86/cpu/qemu/pci.c
@@ -7,6 +7,8 @@
 #include <common.h>
 #include <pci.h>
 #include <pci_rom.h>
+#include <asm/pci.h>
+#include <asm/arch/qemu.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -50,6 +52,8 @@ int board_pci_post_scan(struct pci_controller *hose)
        ulong start;
        pci_dev_t bdf;
        struct pci_device_id graphic_card[] = { { 0x1234, 0x1111 } };
+       u16 device;
+       int pam, i;
 
        /*
         * QEMU emulated graphic card shows in the PCI configuration space with
@@ -67,5 +71,21 @@ int board_pci_post_scan(struct pci_controller *hose)
                debug("BIOS ran in %lums\n", get_timer(start));
        }
 
+       /*
+        * i440FX and Q35 chipset have different PAM register offset, but with
+        * the same bitfield layout. Here we determine the offset based on its
+        * PCI device ID.
+        */
+       device = x86_pci_read_config16(PCI_BDF(0, 0, 0), PCI_DEVICE_ID);
+       pam = (device == PCI_DEVICE_ID_INTEL_82441) ? I440FX_PAM : Q35_PAM;
+
+       /*
+        * Initialize Programmable Attribute Map (PAM) Registers
+        *
+        * Configure legacy segments C/D/E/F to system RAM
+        */
+       for (i = 0; i < PAM_NUM; i++)
+               x86_pci_write_config8(PCI_BDF(0, 0, 0), pam + i, PAM_RW);
+
        return ret;
 }

diff --git a/arch/x86/include/asm/arch-qemu/qemu.h b/arch/x86/include/asm/arch-qemu/qemu.h
index 8d7e9861ca6eeb9aa622bf1a135a9fa0b844078c..7a9901d261be2b3b35723bb5509eb49d53ea7aa9 100644 (file)
--- a/arch/x86/include/asm/arch-qemu/qemu.h
+++ b/arch/x86/include/asm/arch-qemu/qemu.h
@@ -7,6 +7,12 @@
 #ifndef _ARCH_QEMU_H_
 #define _ARCH_QEMU_H_
 
+/* Programmable Attribute Map (PAM) Registers */
+#define I440FX_PAM             0x59
+#define Q35_PAM                        0x90
+#define PAM_NUM                        7
+#define PAM_RW                 0x33
+
 /* I/O Ports */
 #define CMOS_ADDR_PORT         0x70
 #define CMOS_DATA_PORT         0x71