[RFC][PATCH 2/6] ACPI: processor: Introduce acpi_processor_evaluate_cst()

Rafael J. Wysocki
2019-12-06T09:49:51Z

In order to separate the ACPI _CST evaluation from checks
specific to the ACPI processor driver, move the majority of
the acpi_processor_get_power_info_cst() function body to a new
function, acpi_processor_evaluate_cst(), that will extract
the C-states information from _CST output, and redefine
acpi_processor_get_power_info_cst() as a wrapper around it.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/acpi/processor_idle.c | 52 +++++++++++++++++++++++++-----------------
1 file changed, 32 insertions(+), 20 deletions(-)

Index: linux-pm/drivers/acpi/processor_idle.c
===================================================================
--- linux-pm.orig/drivers/acpi/processor_idle.c
+++ linux-pm/drivers/acpi/processor_idle.c
@@ -297,21 +297,17 @@ static int acpi_processor_get_power_info
return 0;
}

-static int acpi_processor_get_power_info_cst(struct acpi_processor *pr)
+static int acpi_processor_evaluate_cst(acpi_handle handle, u32 cpu,
+ struct acpi_processor_power *info)
{
+ struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+ union acpi_object *cst;
acpi_status status;
u64 count;
- int current_count;
+ int current_count = 0;
int i, ret = 0;
- struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
- union acpi_object *cst;
-
- if (nocst)
- return -ENODEV;
-
- current_count = 0;

- status = acpi_evaluate_object(pr->handle, "_CST", NULL, &buffer);
+ status = acpi_evaluate_object(handle, "_CST", NULL, &buffer);
if (ACPI_FAILURE(status)) {
ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No _CST, giving up\n"));
return -ENODEV;
@@ -335,9 +331,6 @@ static int acpi_processor_get_power_info
goto end;
}

- /* Tell driver that at least _CST is supported. */
- pr->flags.has_cst = 1;
-
for (i = 1; i <= count; i++) {
union acpi_object *element;
union acpi_object *obj;
@@ -383,7 +376,7 @@ static int acpi_processor_get_power_info
cx.entry_method = ACPI_CSTATE_SYSTEMIO;
if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
if (acpi_processor_ffh_cstate_probe
- (pr->id, &cx, reg) == 0) {
+ (cpu, &cx, reg) == 0) {
cx.entry_method = ACPI_CSTATE_FFH;
} else if (cx.type == ACPI_STATE_C1) {
/*
@@ -432,7 +425,7 @@ static int acpi_processor_get_power_info
continue;

current_count++;
- memcpy(&(pr->power.states[current_count]), &cx, sizeof(cx));
+ memcpy(&info->states[current_count], &cx, sizeof(cx));

/*
* We support total ACPI_PROCESSOR_MAX_POWER - 1
@@ -446,12 +439,9 @@ static int acpi_processor_get_power_info
}
}

- ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d power states\n",
- current_count));
+ acpi_handle_info(handle, "Found %d idle states\n", current_count);

- /* Validate number of power states discovered */
- if (current_count < 2)
- ret = -EFAULT;
+ info->count = current_count;

end:
kfree(buffer.pointer);
@@ -459,6 +449,28 @@ static int acpi_processor_get_power_info
return ret;
}

+static int acpi_processor_get_power_info_cst(struct acpi_processor *pr)
+{
+ int ret;
+
+ if (nocst)
+ return -ENODEV;
+
+ ret = acpi_processor_evaluate_cst(pr->handle, pr->id, &pr->power);
+ if (ret)
+ return ret;
+
+ /*
+ * It is expected that there will be at least 2 states, C1 and
+ * something else (C2 or C3), so fail if that is not the case.
+ */
+ if (pr->power.count < 2)
+ return -EFAULT;
+
+ pr->flags.has_cst = 1;
+ return 0;
+}
+
static void acpi_processor_power_verify_c3(struct acpi_processor *pr,
struct acpi_processor_cx *cx)
{