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riscv: virt: Add cpu-topology DT node.

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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 <atish.patra@wdc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
This commit is contained in:
Atish Patra 2019-06-24 16:41:44 -07:00 • committed by Palmer Dabbelt
parent ab433cccad
commit 28a4df979a
No known key found for this signature in database
GPG key ID: EF4CA1502CCBAB41
1 changed files with 20 additions and 2 deletions
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22
hw/riscv/virt.c
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@ -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 =