Thread (49 messages) 49 messages, 6 authors, 2020-12-02

Re: [PATCH v3 02/23] psci: Accessor for configured PSCI function IDs

From: Mark Rutland <mark.rutland@arm.com>
Date: 2020-11-26 17:25:13
Also in: kvmarm, linux-doc, lkml

On Thu, Nov 26, 2020 at 03:54:00PM +0000, David Brazdil wrote:
quoted hunk ↗ jump to hunk
Function IDs used by PSCI are configurable for v0.1 via DT/APCI. If the
host is using PSCI v0.1, KVM's host PSCI proxy needs to use the same IDs.
Expose the array holding the information with a read-only accessor.

Signed-off-by: David Brazdil <redacted>
---
 drivers/firmware/psci/psci.c | 16 ++++++++--------
 include/linux/psci.h         | 10 ++++++++++
 2 files changed, 18 insertions(+), 8 deletions(-)
diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
index 213c68418a65..40609564595e 100644
--- a/drivers/firmware/psci/psci.c
+++ b/drivers/firmware/psci/psci.c
@@ -58,16 +58,16 @@ typedef unsigned long (psci_fn)(unsigned long, unsigned long,
 				unsigned long, unsigned long);
 static psci_fn *invoke_psci_fn;
 
-enum psci_function {
-	PSCI_FN_CPU_SUSPEND,
-	PSCI_FN_CPU_ON,
-	PSCI_FN_CPU_OFF,
-	PSCI_FN_MIGRATE,
-	PSCI_FN_MAX,
-};
-
 static u32 psci_function_id[PSCI_FN_MAX];
 
+u32 psci_get_function_id(enum psci_function fn)
+{
+	if (WARN_ON_ONCE(fn < 0 || fn >= PSCI_FN_MAX))
+		return 0;
+
+	return psci_function_id[fn];
+}
I'd really like if we could namespace this with a psci_0_1_* prefix
before we expose it outside of the PSCI code. I appreciate that's a
larger change, but I reckon we only need a couple of new patches:

1) Split the ops which consume the FN ids into separate psci_0_1_*() and
   psci_0_2_*() variants, with a common __psci_*() helper that takes the
   function ID as an argument. The 0_1 variants would read the function
   ID from a variable, and the 0_2 variants would hard-code the id.

2) Replace the psci_function_id array with:

   struct psci_0_1_function_ids {
   	u32 suspend;
   	u32 cpu_on;
   	u32 cpu_off;
   	u32 migrate;
   };

   ... and remove enum psci_function entirely.

3) Add a helper which returns the entire psci_0_1_function_ids struct in
   one go. No warnings necessary.

Does that sound OK to you?

Thanks,
Mark.
quoted hunk ↗ jump to hunk
+
 #define PSCI_0_2_POWER_STATE_MASK		\
 				(PSCI_0_2_POWER_STATE_ID_MASK | \
 				PSCI_0_2_POWER_STATE_TYPE_MASK | \
diff --git a/include/linux/psci.h b/include/linux/psci.h
index 2a1bfb890e58..5b49a5c82d6f 100644
--- a/include/linux/psci.h
+++ b/include/linux/psci.h
@@ -21,6 +21,16 @@ bool psci_power_state_is_valid(u32 state);
 int psci_set_osi_mode(bool enable);
 bool psci_has_osi_support(void);
 
+enum psci_function {
+	PSCI_FN_CPU_SUSPEND,
+	PSCI_FN_CPU_ON,
+	PSCI_FN_CPU_OFF,
+	PSCI_FN_MIGRATE,
+	PSCI_FN_MAX,
+};
+
+u32 psci_get_function_id(enum psci_function fn);
+
 struct psci_operations {
 	u32 (*get_version)(void);
 	int (*cpu_suspend)(u32 state, unsigned long entry_point);
-- 
2.29.2.454.gaff20da3a2-goog
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