fdt adds pch msi controller, we use 'loongson,pch-msi-1.0'.

See:
https://github.com/torvalds/linux/blob/v6.7/drivers/irqchip/irq-loongson-pch-msi.c
https://lore.kernel.org/r/20200528152757.1028711-6-jiaxun.yang@flygoat.com

Signed-off-by: Song Gao <gaosong@loongson.cn>
---
 include/hw/pci-host/ls7a.h |  1 +
 hw/loongarch/virt.c        | 33 ++++++++++++++++++++++++++++++++-
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/include/hw/pci-host/ls7a.h b/include/hw/pci-host/ls7a.h
index fe260f0183..cd7c9ec7bc 100644
--- a/include/hw/pci-host/ls7a.h
+++ b/include/hw/pci-host/ls7a.h
@@ -25,6 +25,7 @@
 #define VIRT_IOAPIC_REG_BASE     (VIRT_PCH_REG_BASE)
 #define VIRT_PCH_MSI_ADDR_LOW    0x2FF00000UL
 #define VIRT_PCH_REG_SIZE        0x400
+#define VIRT_PCH_MSI_SIZE        0x8
 
 /*
  * GSI_BASE is hard-coded with 64 in linux kernel, else kernel fails to boot
diff --git a/hw/loongarch/virt.c b/hw/loongarch/virt.c
index 87908d1f79..e1fe1ea97f 100644
--- a/hw/loongarch/virt.c
+++ b/hw/loongarch/virt.c
@@ -150,6 +150,34 @@ static void fdt_add_pch_pic_node(LoongArchMachineState *lams,
     g_free(nodename);
 }
 
+static void fdt_add_pch_msi_node(LoongArchMachineState *lams,
+                                 uint32_t *eiointc_phandle,
+                                 uint32_t *pch_msi_phandle)
+{
+    MachineState *ms = MACHINE(lams);
+    char *nodename;
+    hwaddr pch_msi_base = VIRT_PCH_MSI_ADDR_LOW;
+    hwaddr pch_msi_size = VIRT_PCH_MSI_SIZE;
+
+    *pch_msi_phandle = qemu_fdt_alloc_phandle(ms->fdt);
+    nodename = g_strdup_printf("/msi@%" PRIx64, pch_msi_base);
+    qemu_fdt_add_subnode(ms->fdt, nodename);
+    qemu_fdt_setprop_cell(ms->fdt, nodename, "phandle", *pch_msi_phandle);
+    qemu_fdt_setprop_string(ms->fdt, nodename, "compatible",
+                            "loongson,pch-msi-1.0");
+    qemu_fdt_setprop_cells(ms->fdt, nodename, "reg",
+                           0, pch_msi_base,
+                           0, pch_msi_size);
+    qemu_fdt_setprop(ms->fdt, nodename, "interrupt-controller", NULL, 0);
+    qemu_fdt_setprop_cell(ms->fdt, nodename, "interrupt-parent",
+                          *eiointc_phandle);
+    qemu_fdt_setprop_cell(ms->fdt, nodename, "loongson,msi-base-vec",
+                          VIRT_PCH_PIC_IRQ_NUM);
+    qemu_fdt_setprop_cell(ms->fdt, nodename, "loongson,msi-num-vecs",
+                          EXTIOI_IRQS - VIRT_PCH_PIC_IRQ_NUM);
+    g_free(nodename);
+}
+
 static void fdt_add_flash_node(LoongArchMachineState *lams)
 {
     MachineState *ms = MACHINE(lams);
@@ -558,7 +586,7 @@ static void loongarch_irq_init(LoongArchMachineState *lams)
     CPULoongArchState *env;
     CPUState *cpu_state;
     int cpu, pin, i, start, num;
-    uint32_t cpuintc_phandle, eiointc_phandle, pch_pic_phandle;
+    uint32_t cpuintc_phandle, eiointc_phandle, pch_pic_phandle, pch_msi_phandle;
 
     /*
      * The connection of interrupts:
@@ -666,6 +694,9 @@ static void loongarch_irq_init(LoongArchMachineState *lams)
                               qdev_get_gpio_in(extioi, i + start));
     }
 
+    /* Add PCH MSI node */
+    fdt_add_pch_msi_node(lams, &eiointc_phandle, &pch_msi_phandle);
+
     loongarch_devices_init(pch_pic, lams);
 }
 
-- 
2.25.1