[PATCH v6 02/33] hw/mips/malta: Set PIIX4 IRQ routes in embedded bootloader

[Bernhard Beschow <shentey@gmail.com>]

From: Philippe Mathieu-Daudé <philmd@linaro.org>

Linux kernel expects the northbridge & southbridge chipsets
configured by the BIOS firmware. We emulate that by writing
a tiny bootloader code in write_bootloader().

Upon introduction in commit 5c2b87e34d ("PIIX4 support"),
the PIIX4 configuration space included values specific to
the Malta board.

Set the Malta-specific IRQ routing values in the embedded
bootloader, so the next commit can remove the Malta specific
bits from the PIIX4 PCI-ISA bridge and make it generic
(matching the real hardware).

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20221027204720.33611-3-philmd@linaro.org>
---
 hw/mips/malta.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/hw/mips/malta.c b/hw/mips/malta.c
index 9bffa1b128..c3dcd43f37 100644
--- a/hw/mips/malta.c
+++ b/hw/mips/malta.c
@@ -803,6 +803,8 @@ static void write_bootloader_nanomips(uint8_t *base, uint64_t run_addr,
     stw_p(p++, 0x8422); stw_p(p++, 0x9088);
                                 /* sw t0, 0x88(t1)              */
 
+    /* TODO set PIIX IRQC[A:D] routing values! */
+
     stw_p(p++, 0xe320 | NM_HI1(kernel_entry));
 
     stw_p(p++, NM_HI2(kernel_entry));
@@ -840,6 +842,9 @@ static void write_bootloader_nanomips(uint8_t *base, uint64_t run_addr,
 static void write_bootloader(uint8_t *base, uint64_t run_addr,
                              uint64_t kernel_entry)
 {
+    const char pci_pins_cfg[PCI_NUM_PINS] = {
+        10, 10, 11, 11 /* PIIX IRQRC[A:D] */
+    };
     uint32_t *p;
 
     /* Small bootloader */
@@ -914,6 +919,20 @@ static void write_bootloader(uint8_t *base, uint64_t run_addr,
 
 #undef cpu_to_gt32
 
+    /*
+     * The PIIX ISA bridge is on PCI bus 0 dev 10 func 0.
+     * Load the PIIX IRQC[A:D] routing config address, then
+     * write routing configuration to the config data register.
+     */
+    bl_gen_write_u32(&p, /* GT_PCI0_CFGADDR */
+                     cpu_mips_phys_to_kseg1(NULL, 0x1be00000 + 0xcf8),
+                     tswap32((1 << 31) /* ConfigEn */
+                             | PCI_BUILD_BDF(0, PIIX4_PCI_DEVFN) << 8
+                             | PIIX_PIRQCA));
+    bl_gen_write_u32(&p, /* GT_PCI0_CFGDATA */
+                     cpu_mips_phys_to_kseg1(NULL, 0x1be00000 + 0xcfc),
+                     tswap32(ldl_be_p(pci_pins_cfg)));
+
     bl_gen_jump_kernel(&p,
                        true, ENVP_VADDR - 64,
                        /*
-- 
2.39.0