Re: [PATCH v3 3/7] drivers: base: cacheinfo: arm64: Add support for ACPI based firmware tables

From: Jeremy Linton
Date: Thu Oct 19 2017 - 11:52:41 EST

Hi,


On 10/19/2017 10:20 AM, Lorenzo Pieralisi wrote:
On Thu, Oct 12, 2017 at 02:48:52PM -0500, Jeremy Linton wrote:
The /sys cache entries should support ACPI/PPTT generated cache
topology information. Lets detect ACPI systems and call
an arch specific cache_setup_acpi() routine to update the hardware
probed cache topology.

For arm64, if ACPI is enabled, determine the max number of cache
levels and populate them using a PPTT table if one is available.

Signed-off-by: Jeremy Linton <jeremy.linton@xxxxxxx>
---
arch/arm64/kernel/cacheinfo.c | 23 ++++++++++++++++++-----
drivers/acpi/pptt.c | 1 +
drivers/base/cacheinfo.c | 17 +++++++++++------
include/linux/cacheinfo.h | 11 +++++++++--
4 files changed, 39 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/kernel/cacheinfo.c b/arch/arm64/kernel/cacheinfo.c
index 380f2e2fbed5..2e2cf0d312ba 100644
--- a/arch/arm64/kernel/cacheinfo.c
+++ b/arch/arm64/kernel/cacheinfo.c
@@ -17,6 +17,7 @@
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <linux/acpi.h>
#include <linux/cacheinfo.h>
#include <linux/of.h>
@@ -44,9 +45,17 @@ static void ci_leaf_init(struct cacheinfo *this_leaf,
this_leaf->type = type;
}
+#ifndef CONFIG_ACPI
+int acpi_find_last_cache_level(unsigned int cpu)
+{
+ /*ACPI kernels should be built with PPTT support*/
+ return 0;
+}
+#endif
+
static int __init_cache_level(unsigned int cpu)
{
- unsigned int ctype, level, leaves, of_level;
+ unsigned int ctype, level, leaves, fw_level;
struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
for (level = 1, leaves = 0; level <= MAX_CACHE_LEVEL; level++) {
@@ -59,15 +68,19 @@ static int __init_cache_level(unsigned int cpu)
leaves += (ctype == CACHE_TYPE_SEPARATE) ? 2 : 1;
}
- of_level = of_find_last_cache_level(cpu);
- if (level < of_level) {
+ if (acpi_disabled)
+ fw_level = of_find_last_cache_level(cpu);
+ else
+ fw_level = acpi_find_last_cache_level(cpu);
+
+ if (level < fw_level) {
/*
* some external caches not specified in CLIDR_EL1
* the information may be available in the device tree
* only unified external caches are considered here
*/
- leaves += (of_level - level);
- level = of_level;
+ leaves += (fw_level - level);
+ level = fw_level;
}
this_cpu_ci->num_levels = level;
diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
index c86715fed4a7..b5c6de37e328 100644
--- a/drivers/acpi/pptt.c
+++ b/drivers/acpi/pptt.c
@@ -355,6 +355,7 @@ static void update_cache_properties(struct cacheinfo *this_leaf,
struct acpi_pptt_cache *found_cache,
struct acpi_pptt_processor *cpu_node)
{
+ this_leaf->firmware_node = cpu_node;

This pointer comes from an ACPI static table mapping that happens
to be permanent so it should be safe given that the mapping is carried
out at device_initcall (ie cache_setup_acpi()) but it is not that
obvious. More to it below.

if (found_cache->flags & ACPI_PPTT_SIZE_PROPERTY_VALID)
this_leaf->size = found_cache->size;
if (found_cache->flags & ACPI_PPTT_LINE_SIZE_VALID)
diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index eb3af2739537..8eca279e50d1 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -86,7 +86,7 @@ static int cache_setup_of_node(unsigned int cpu)
static inline bool cache_leaves_are_shared(struct cacheinfo *this_leaf,
struct cacheinfo *sib_leaf)
{
- return sib_leaf->of_node == this_leaf->of_node;
+ return sib_leaf->firmware_node == this_leaf->firmware_node;
}
/* OF properties to query for a given cache type */
@@ -215,6 +215,11 @@ static inline bool cache_leaves_are_shared(struct cacheinfo *this_leaf,
}
#endif
+int __weak cache_setup_acpi(unsigned int cpu)
+{
+ return -ENOTSUPP;
+}
+
static int cache_shared_cpu_map_setup(unsigned int cpu)
{
struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
@@ -225,11 +230,11 @@ static int cache_shared_cpu_map_setup(unsigned int cpu)
if (this_cpu_ci->cpu_map_populated)
return 0;
- if (of_have_populated_dt())
+ if (!acpi_disabled)
+ ret = cache_setup_acpi(cpu);
+ else if (of_have_populated_dt())
ret = cache_setup_of_node(cpu);
- else if (!acpi_disabled)
- /* No cache property/hierarchy support yet in ACPI */
- ret = -ENOTSUPP;
+
if (ret)
return ret;
@@ -286,7 +291,7 @@ static void cache_shared_cpu_map_remove(unsigned int cpu)
static void cache_override_properties(unsigned int cpu)
{
- if (of_have_populated_dt())
+ if (acpi_disabled && of_have_populated_dt())
return cache_of_override_properties(cpu);
}
diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
index 6a524bf6a06d..d1e9b8e01981 100644
--- a/include/linux/cacheinfo.h
+++ b/include/linux/cacheinfo.h
@@ -36,6 +36,9 @@ enum cache_type {
* @of_node: if devicetree is used, this represents either the cpu node in
* case there's no explicit cache node or the cache node itself in the
* device tree
+ * @firmware_node: Shared with of_node. When not using DT, this may contain
+ * pointers to other firmware based values. Particularly ACPI/PPTT
+ * unique values.
* @disable_sysfs: indicates whether this node is visible to the user via
* sysfs or not
* @priv: pointer to any private data structure specific to particular
@@ -64,8 +67,10 @@ struct cacheinfo {
#define CACHE_ALLOCATE_POLICY_MASK \
(CACHE_READ_ALLOCATE | CACHE_WRITE_ALLOCATE)
#define CACHE_ID BIT(4)
-
- struct device_node *of_node;
+ union {
+ struct device_node *of_node;
+ void *firmware_node;
+ };

How about turning of_node into a struct fwnode_handle* (and allocate
one for each PPTT cache node - acpi_static_fwnode - to have the
ACPI counterpart) ?

As pointed out internally (with a patch), I converted this whole module into fwnode, but the ACPI side is still a mess because it doesn't map cleanly to what ends up being an relative acpi pointer, mostly because fwnode is really designed more for parsing DT and the ACPI DSDT/etc. So you end up with fwnode routines that simply don't have mappings to PPTT, with IMHO is going to just create far more confusion than any assumed cleanliness that might result.


It will make more churn given that that pointer is just used to
carry out a pointer comparison but it's also a bit more elegant.

Except for the huge api surface that takes a fwnode which won't work.


Lorenzo

bool disable_sysfs;
void *priv;
};
@@ -98,6 +103,8 @@ int func(unsigned int cpu) \
struct cpu_cacheinfo *get_cpu_cacheinfo(unsigned int cpu);
int init_cache_level(unsigned int cpu);
int populate_cache_leaves(unsigned int cpu);
+int cache_setup_acpi(unsigned int cpu);
+int acpi_find_last_cache_level(unsigned int cpu);
const struct attribute_group *cache_get_priv_group(struct cacheinfo *this_leaf);
--
2.13.5