Re: [PATCH v5 1/9] RISC-V: Add riscv_fw_parent_hartid() function

Andrew Jones
2023-07-11T13:26:26Z

On Mon, Jul 10, 2023 at 03:13:13PM +0530, Anup Patel wrote:
> We add common riscv_fw_parent_hartid() which help device drivers
> to get parent hartid of the INTC (i.e. local interrupt controller)
> fwnode. This should work for both DT and ACPI.
>
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> ---
> arch/riscv/include/asm/processor.h | 3 +++
> arch/riscv/kernel/cpu.c | 16 ++++++++++++++++
> 2 files changed, 19 insertions(+)
>
> diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
> index c950a8d9edef..39dc23a18f88 100644
> --- a/arch/riscv/include/asm/processor.h
> +++ b/arch/riscv/include/asm/processor.h
> @@ -81,6 +81,9 @@ int riscv_of_processor_hartid(struct device_node *node, unsigned long *hartid);
> int riscv_early_of_processor_hartid(struct device_node *node, unsigned long *hartid);
> int riscv_of_parent_hartid(struct device_node *node, unsigned long *hartid);
>
> +struct fwnode_handle;
> +int riscv_fw_parent_hartid(struct fwnode_handle *node, unsigned long *hartid);
> +
> extern void riscv_fill_hwcap(void);
> extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
>
> diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
> index a2fc952318e9..9be9b3b1f333 100644
> --- a/arch/riscv/kernel/cpu.c
> +++ b/arch/riscv/kernel/cpu.c
> @@ -96,6 +96,22 @@ int riscv_of_parent_hartid(struct device_node *node, unsigned long *hartid)
> return -1;
> }
>
> +/* Find hart ID of the CPU fwnode under which given fwnode falls. */

This comment matches the comment for riscv_of_parent_hartid(), but I don't
think it will be correct for the !is_of_node(node) case since
fwnode_property_read_u64_array() isn't obliged to walk up its tree.
Looking ahead it appears riscv_fw_parent_hartid() is only called with the
parent node, so we could just drop this function and use
fwnode_property_read_u64_array() directly at the two call sites.

Thanks,
drew

> +int riscv_fw_parent_hartid(struct fwnode_handle *node, unsigned long *hartid)
> +{
> + int rc;
> + u64 temp;
> +
> + if (!is_of_node(node)) {
> + rc = fwnode_property_read_u64_array(node, "hartid", &temp, 1);
> + if (!rc)
> + *hartid = temp;
> + } else
> + rc = riscv_of_parent_hartid(to_of_node(node), hartid);
> +
> + return rc;
> +}
> +
> DEFINE_PER_CPU(struct riscv_cpuinfo, riscv_cpuinfo);
>
> unsigned long riscv_cached_mvendorid(unsigned int cpu_id)
> --
> 2.34.1