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SubjectRe: [PATCH 1/2] arch_topology: support for describing cache topology from DT
On Thu, Apr 21, 2022 at 07:55:57AM -0700, Qing Wang wrote:
> From: Wang Qing <wangqing@vivo.com>
>
> When ACPI is not enabled, we can get cache topolopy from DT like:
> * cpu0: cpu@000 {
> * next-level-cache = <&L2_1>;
> * L2_1: l2-cache {
> * compatible = "cache";
> * next-level-cache = <&L3_1>;
> * };
> * L3_1: l3-cache {
> * compatible = "cache";
> * };
> * };
> *
> * cpu1: cpu@001 {
> * next-level-cache = <&L2_1>;
> * };
> * ...
> * };
> cache_topology hold the pointer describing "next-level-cache",
> it can describe the cache topology of every level.
>
> Signed-off-by: Wang Qing <wangqing@vivo.com>
> ---
> drivers/base/arch_topology.c | 47 ++++++++++++++++++++++++++++++++++-
> include/linux/arch_topology.h | 3 +++
> 2 files changed, 49 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
> index 1d6636ebaac5..46e84ce2ec0c 100644
> --- a/drivers/base/arch_topology.c
> +++ b/drivers/base/arch_topology.c
> @@ -480,8 +480,10 @@ static int __init get_cpu_for_node(struct device_node *node)
> return -1;
>
> cpu = of_cpu_node_to_id(cpu_node);
> - if (cpu >= 0)
> + if (cpu >= 0) {
> topology_parse_cpu_capacity(cpu_node, cpu);
> + topology_parse_cpu_caches(cpu_node, cpu);
> + }
> else
> pr_info("CPU node for %pOF exist but the possible cpu range is :%*pbl\n",
> cpu_node, cpumask_pr_args(cpu_possible_mask));
> @@ -647,6 +649,49 @@ static int __init parse_dt_topology(void)
> }
> #endif
>
> +/*
> + * cpu cache topology table
> + */
> +#define MAX_CACHE_LEVEL 7
> +staic struct device_node *cache_topology[NR_CPUS][MAX_CACHE_LEVEL];
> +
> +void topology_parse_cpu_caches(struct device_node *cpu_node, int cpu)
> +{
> + struct device_node *node_cache = cpu_node;
> + int level = 0;
> +
> + while (level < MAX_CACHE_LEVEL) {
> + node_cache = of_parse_phandle(node_cache, "next-level-cache", 0);
> + if (!node_cache)
> + break;
> +
> + cache_topology[cpu][level++] = node_cache;
> + }
> +}
> +
> +/*
> + * find the maximum level shared cache under giving mask
> + */
> +void find_max_sub_sc(const struct cpumask *giving_mask, int cpu,
> + struct cpumask *sc_mask)

This is not a good global function name. No one will know what this
means when they read it. Please make it make more sense.

thanks,

greg k-h

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