[Qemu-riscv] [PULL 25/32] riscv: virt: Add cpu-topology DT node.

[Palmer Dabbelt]

From: Atish Patra <address@hidden>

Currently, there is no cpu topology defined in RISC-V.
Define a device tree node that clearly describes the
entire topology. This saves the trouble of scanning individual
cache to figure out the topology.

Here is the linux kernel patch series that enables topology
for RISC-V.

http://lists.infradead.org/pipermail/linux-riscv/2019-June/005072.html

CPU topology after applying this patch in QEMU & above series in kernel

/ # cat /sys/devices/system/cpu/cpu2/topology/thread_siblings_list
2
/ # cat /sys/devices/system/cpu/cpu2/topology/physical_package_id
0
/ # cat /sys/devices/system/cpu/cpu2/topology/core_siblings_list
0-7

Signed-off-by: Atish Patra <address@hidden>
Reviewed-by: Alistair Francis <address@hidden>
Signed-off-by: Palmer Dabbelt <address@hidden>
---
 hw/riscv/virt.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
index 487f61404b21..28d96daf8c5b 100644
--- a/hw/riscv/virt.c
+++ b/hw/riscv/virt.c
@@ -191,6 +191,7 @@ static void *create_fdt(RISCVVirtState *s, const struct 
MemmapEntry *memmap,
 
     for (cpu = s->soc.num_harts - 1; cpu >= 0; cpu--) {
         int cpu_phandle = phandle++;
+        int intc_phandle;
         nodename = g_strdup_printf("/cpus/cpu@%d", cpu);
         char *intc = g_strdup_printf("/cpus/cpu@%d/interrupt-controller", cpu);
         char *isa = riscv_isa_string(&s->soc.harts[cpu]);
@@ -203,9 +204,12 @@ static void *create_fdt(RISCVVirtState *s, const struct 
MemmapEntry *memmap,
         qemu_fdt_setprop_string(fdt, nodename, "status", "okay");
         qemu_fdt_setprop_cell(fdt, nodename, "reg", cpu);
         qemu_fdt_setprop_string(fdt, nodename, "device_type", "cpu");
+        qemu_fdt_setprop_cell(fdt, nodename, "phandle", cpu_phandle);
+        qemu_fdt_setprop_cell(fdt, nodename, "linux,phandle", cpu_phandle);
+        intc_phandle = phandle++;
         qemu_fdt_add_subnode(fdt, intc);
-        qemu_fdt_setprop_cell(fdt, intc, "phandle", cpu_phandle);
-        qemu_fdt_setprop_cell(fdt, intc, "linux,phandle", cpu_phandle);
+        qemu_fdt_setprop_cell(fdt, intc, "phandle", intc_phandle);
+        qemu_fdt_setprop_cell(fdt, intc, "linux,phandle", intc_phandle);
         qemu_fdt_setprop_string(fdt, intc, "compatible", "riscv,cpu-intc");
         qemu_fdt_setprop(fdt, intc, "interrupt-controller", NULL, 0);
         qemu_fdt_setprop_cell(fdt, intc, "#interrupt-cells", 1);
@@ -214,6 +218,20 @@ static void *create_fdt(RISCVVirtState *s, const struct 
MemmapEntry *memmap,
         g_free(nodename);
     }
 
+    /* Add cpu-topology node */
+    qemu_fdt_add_subnode(fdt, "/cpus/cpu-map");
+    qemu_fdt_add_subnode(fdt, "/cpus/cpu-map/cluster0");
+    for (cpu = s->soc.num_harts - 1; cpu >= 0; cpu--) {
+        char *core_nodename = g_strdup_printf("/cpus/cpu-map/cluster0/core%d",
+                                              cpu);
+        char *cpu_nodename = g_strdup_printf("/cpus/cpu@%d", cpu);
+        uint32_t intc_phandle = qemu_fdt_get_phandle(fdt, cpu_nodename);
+        qemu_fdt_add_subnode(fdt, core_nodename);
+        qemu_fdt_setprop_cell(fdt, core_nodename, "cpu", intc_phandle);
+        g_free(core_nodename);
+        g_free(cpu_nodename);
+    }
+
     cells =  g_new0(uint32_t, s->soc.num_harts * 4);
     for (cpu = 0; cpu < s->soc.num_harts; cpu++) {
         nodename =
-- 
2.21.0