On 2017/1/13 2:29, Sudeep Holla wrote:
> It is useful to have helper function just to get the number of cache
> levels for a given logical cpu. We can obtain the same by just checking
> the level at which the last cache is present. This patch adds support
> to find the level of the last cache for a given cpu.
>
> It will be used on ARM64 platform where the device tree provides the
> information for the additional non-architected/transparent/external
> last level caches that are not integrated with the processors.
>
> Suggested-by: Rob Herring <robh+dt@xxxxxxxxxx>
> Cc: Rob Herring <robh+dt@xxxxxxxxxx>
> Cc: Mark Rutland <mark.rutland@xxxxxxx>
> Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
Tested-by: Tan Xiaojun <tanxiaojun@xxxxxxxxxx>
> ---
> drivers/of/base.c | 27 +++++++++++++++++++++++++++
> include/linux/of.h | 1 +
> 2 files changed, 28 insertions(+)
>
> v1->v2:
> - Moved to using "cache-level" in the last level cache instead
> of counting through all the nodes as suggested by Rob
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index d4bea3c797d6..c1128a077aea 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -25,6 +25,7 @@
> #include <linux/cpu.h>
> #include <linux/module.h>
> #include <linux/of.h>
> +#include <linux/of_device.h>
> #include <linux/of_graph.h>
> #include <linux/spinlock.h>
> #include <linux/slab.h>
> @@ -2268,6 +2269,32 @@ struct device_node *of_find_next_cache_node(const struct device_node *np)
> }
>
> /**
> + * of_find_last_cache_level - Find the level at which the last cache is
> + * present for the given logical cpu
> + *
> + * @cpu: cpu number(logical index) for which the last cache level is needed
> + *
> + * Returns the the level at which the last cache is present. It is exactly
> + * same as the total number of cache levels for the given logical cpu.
> + */
> +int of_find_last_cache_level(unsigned int cpu)
> +{
> + int cache_level = 0;
> + struct device_node *prev = NULL, *np = of_cpu_device_node_get(cpu);
> +
> + while (np) {
> + prev = np;
> + of_node_put(np);
> + np = of_find_next_cache_node(np);
> + }
> +
> + if (prev)
> + of_property_read_u32(prev, "cache-level", &cache_level);
> +
> + return cache_level;
> +}
> +
> +/**
> * of_graph_parse_endpoint() - parse common endpoint node properties
> * @node: pointer to endpoint device_node
> * @endpoint: pointer to the OF endpoint data structure
> diff --git a/include/linux/of.h b/include/linux/of.h
> index d72f01009297..21e6323de0f3 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -280,6 +280,7 @@ extern struct device_node *of_get_child_by_name(const struct device_node *node,
>
> /* cache lookup */
> extern struct device_node *of_find_next_cache_node(const struct device_node *);
> +extern int of_find_last_cache_level(unsigned int cpu);
> extern struct device_node *of_find_node_with_property(
> struct device_node *from, const char *prop_name);
>
> --
> 2.7.4
>
>
> .
>
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