PSCI: Use DT Function ID values only for old versions of spec

The PSCI v0.2+ spec defines static values for PSCI function IDs. Add a new binding entry so that pre v0.2 implementations can use DT entries for function IDs and v0.2+ implementations use static entries as defined by the PSCIv0.2 specification.

Signed-off-by Ashwin Chaugule <[email protected]>

---
 Documentation/devicetree/bindings/arm/psci.txt | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Documentation/devicetree/bindings/arm/psci.txt +0 -0

index 433afe9..a808284 100644

Quoted 16 lines · Ashwin Chaugule

The PSCI v0.2+ spec defines static values for PSCI function IDs. Add a new binding entry so that pre v0.2 implementations can use DT entries for function IDs and v0.2+ implementations use static entries as defined by the PSCIv0.2 specification.

Signed-off-by Ashwin Chaugule <[email protected]>

---
 Documentation/devicetree/bindings/arm/psci.txt | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Documentation/devicetree/bindings/arm/psci.txt +0 -0

index 433afe9..a808284 100644
@@ -21,7 +21,11 @@ to #0.
 

Documentation/devicetree/bindings/arm/psci.txt to #0. · line 28

Quoted 8 lines

Documentation/devicetree/bindings/arm/psci.txt +5 -1

 Main node required properties:
 
- - compatible    : Must be "arm,psci"
+ - compatible    : "arm,psci" : pre PSCIv0.2 spec implementations use this
+                   to get the function IDs from DT entries.
+
+                   "arm,psci-0.2": PSCIv0.2+ spec implementations use static
+                   values for function IDs as defined in the spec.

Maybe specify that in this case no function IDs are passed in the device tree?

Quoted 17 lines · Christoffer Dall

Quoted 16 lines · Ashwin Chaugule

The PSCI v0.2+ spec defines static values for PSCI function IDs. Add a new binding entry so that pre v0.2 implementations can use DT entries for function IDs and v0.2+ implementations use static entries as defined by the PSCIv0.2 specification.

Signed-off-by Ashwin Chaugule <[email protected]>

---
 Documentation/devicetree/bindings/arm/psci.txt | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Documentation/devicetree/bindings/arm/psci.txt +0 -0

index 433afe9..a808284 100644
@@ -21,7 +21,11 @@ to #0.
 

Quoted 8 lines

Documentation/devicetree/bindings/arm/psci.txt to #0. · line 28

Quoted 8 lines

Documentation/devicetree/bindings/arm/psci.txt +5 -1

 Main node required properties:
 
- - compatible    : Must be "arm,psci"
+ - compatible    : "arm,psci" : pre PSCIv0.2 spec implementations use this
+                   to get the function IDs from DT entries.
+
+                   "arm,psci-0.2": PSCIv0.2+ spec implementations use static
+                   values for function IDs as defined in the spec.

How about:

- compatible: should contain at least one of:

* "arm,psci" : for implementations complying to PSCI versions prior to 0.2. For these cases function IDs must be provided.

* "arm,psci-0.2" : for implementations complying to PSCI 0.2. Function IDs are not required and should be ignored by an OS with PSCI 0.2 support, but are permitted to be present for compatibility with existing software when "arm,psci" is later in the compatible list.

Quoted 2 lines

Maybe specify that in this case no function IDs are passed in the device tree?

As described above, for compatibility with existing kernels, the hypervisor will likely want to provide IDs, e.g.

psci {
        compatible = "arm,psci-0.2", "arm,psci";
        method = "hvc";

        cpu_on = < arbitrary value >;
        cpu_off = < arbitrary value >;

        ...
};

In this case I'd expect an OS with PSCI 0.2 support to use the PSCI 0.2 IDs, but an older OS would use the IDs from the DT (which may or may not match the PSCI 0.2 IDs).

So while we should say is any function IDs should be ignored for "arm,psci-0.2", we shouldn't say that they are disallowed in the node.

The document should have examples of "arm,psci" only, "arm,psci-0.2" only, and the compatibility case.

The PSCI v0.2+ spec mandates specific values of Function IDs for ARM32 and ARM64. Use DT bindings of Function IDs only when using older versions. Use static values otherwise. This patch also prepares the code to easily use the ACPI API which is based off of PSCI v0.2+.

Signed-off-by Ashwin Chaugule <[email protected]>

---
 arch/arm/include/asm/psci.h   |  15 ++++++
 arch/arm/kernel/psci.c        | 110 +++++++++++++++++++++++++++++++++++++-----
 arch/arm64/include/asm/psci.h |  12 +++++
 arch/arm64/kernel/psci.c      | 106 +++++++++++++++++++++++++++++++++++-----
 4 files changed, 218 insertions(+), 25 deletions(-)

arch/arm/include/asm/psci.h +2 -0

index c4ae171..3f8ebf9 100644
@@ -17,6 +17,19 @@
 #define PSCI_POWER_STATE_TYPE_STANDBY          0
 #define PSCI_POWER_STATE_TYPE_POWER_DOWN       1
 
+/* PSCI Function ID's for ARM32 as per PSCI spec v0.2 */
+

Quoted 31 lines · Ashwin Chaugule

The PSCI v0.2+ spec mandates specific values of Function IDs for ARM32 and ARM64. Use DT bindings of Function IDs only when using older versions. Use static values otherwise. This patch also prepares the code to easily use the ACPI API which is based off of PSCI v0.2+.

Signed-off-by Ashwin Chaugule <[email protected]>

---
 arch/arm/include/asm/psci.h   |  15 ++++++
 arch/arm/kernel/psci.c        | 110 +++++++++++++++++++++++++++++++++++++-----
 arch/arm64/include/asm/psci.h |  12 +++++
 arch/arm64/kernel/psci.c      | 106 +++++++++++++++++++++++++++++++++++-----
 4 files changed, 218 insertions(+), 25 deletions(-)

arch/arm/include/asm/psci.h +9 -0

index c4ae171..3f8ebf9 100644
@@ -17,6 +17,19 @@
 #define PSCI_POWER_STATE_TYPE_STANDBY          0
 #define PSCI_POWER_STATE_TYPE_POWER_DOWN       1
 
+/* PSCI Function ID's for ARM32 as per PSCI spec v0.2 */
+
+#define PSCI_ID_VERSION                                0x84000000
+#define PSCI_ID_CPU_SUSPEND                    0x84000001
+#define PSCI_ID_CPU_OFF                                0x84000002
+#define PSCI_ID_CPU_ON                         0x84000003
+#define PSCI_ID_AFFINITY_INFO          0x84000004
+#define PSCI_ID_CPU_MIGRATE                    0x84000005
+#define PSCI_ID_MIGRATE_INFO_TYPE      0x84000006

arch/arm/include/asm/psci.h line 31

Quoted 3 lines

arch/arm/include/asm/psci.h +3 -0

+#define PSCI_ID_MIGRATE_INFO_UP_CPU    0x84000007
+#define PSCI_ID_SYSTEM_OFF                     0x84000008
+#define PSCI_ID_SYSTEM_RESET           0x84000009

With the KVM patches[1], this makes 4 copies of these defines in the kernel (and then QEMU has more). This needs to go into a common header under include/linux. Probably under uapi so QEMU can use. There is some sync of headers between the kernel and QEMU I think.

Quoted 31 lines · Ashwin Chaugule

The PSCI v0.2+ spec mandates specific values of Function IDs for ARM32 and ARM64. Use DT bindings of Function IDs only when using older versions. Use static values otherwise. This patch also prepares the code to easily use the ACPI API which is based off of PSCI v0.2+.

Signed-off-by Ashwin Chaugule <[email protected]>

---
 arch/arm/include/asm/psci.h   |  15 ++++++
 arch/arm/kernel/psci.c        | 110 +++++++++++++++++++++++++++++++++++++-----
 arch/arm64/include/asm/psci.h |  12 +++++
 arch/arm64/kernel/psci.c      | 106 +++++++++++++++++++++++++++++++++++-----
 4 files changed, 218 insertions(+), 25 deletions(-)

arch/arm/include/asm/psci.h +9 -0

index c4ae171..3f8ebf9 100644
@@ -17,6 +17,19 @@
 #define PSCI_POWER_STATE_TYPE_STANDBY          0
 #define PSCI_POWER_STATE_TYPE_POWER_DOWN       1
 
+/* PSCI Function ID's for ARM32 as per PSCI spec v0.2 */
+
+#define PSCI_ID_VERSION                                0x84000000
+#define PSCI_ID_CPU_SUSPEND                    0x84000001
+#define PSCI_ID_CPU_OFF                                0x84000002
+#define PSCI_ID_CPU_ON                         0x84000003
+#define PSCI_ID_AFFINITY_INFO          0x84000004
+#define PSCI_ID_CPU_MIGRATE                    0x84000005
+#define PSCI_ID_MIGRATE_INFO_TYPE      0x84000006

arch/arm/include/asm/psci.h line 31

Quoted 3 lines

arch/arm/include/asm/psci.h +3 -0

+#define PSCI_ID_MIGRATE_INFO_UP_CPU    0x84000007
+#define PSCI_ID_SYSTEM_OFF                     0x84000008
+#define PSCI_ID_SYSTEM_RESET           0x84000009

With the KVM patches[1], this makes 4 copies of these defines in the kernel (and then QEMU has more). This needs to go into a common header under include/linux. Probably under uapi so QEMU can use. There is some sync of headers between the kernel and QEMU I think.

Rob

[1] https://patches.linaro.org/23918/

Quoted 33 lines · Rob Herring

Quoted 31 lines · Ashwin Chaugule

The PSCI v0.2+ spec mandates specific values of Function IDs for ARM32 and ARM64. Use DT bindings of Function IDs only when using older versions. Use static values otherwise. This patch also prepares the code to easily use the ACPI API which is based off of PSCI v0.2+.

Signed-off-by Ashwin Chaugule <[email protected]>

---
 arch/arm/include/asm/psci.h   |  15 ++++++
 arch/arm/kernel/psci.c        | 110 +++++++++++++++++++++++++++++++++++++-----
 arch/arm64/include/asm/psci.h |  12 +++++
 arch/arm64/kernel/psci.c      | 106 +++++++++++++++++++++++++++++++++++-----
 4 files changed, 218 insertions(+), 25 deletions(-)

arch/arm/include/asm/psci.h +9 -0

index c4ae171..3f8ebf9 100644
@@ -17,6 +17,19 @@
 #define PSCI_POWER_STATE_TYPE_STANDBY          0
 #define PSCI_POWER_STATE_TYPE_POWER_DOWN       1
 
+/* PSCI Function ID's for ARM32 as per PSCI spec v0.2 */
+
+#define PSCI_ID_VERSION                                0x84000000
+#define PSCI_ID_CPU_SUSPEND                    0x84000001
+#define PSCI_ID_CPU_OFF                                0x84000002
+#define PSCI_ID_CPU_ON                         0x84000003
+#define PSCI_ID_AFFINITY_INFO          0x84000004
+#define PSCI_ID_CPU_MIGRATE                    0x84000005
+#define PSCI_ID_MIGRATE_INFO_TYPE      0x84000006

Quoted 8 lines

arch/arm/include/asm/psci.h line 31

Quoted 3 lines

arch/arm/include/asm/psci.h +3 -0

+#define PSCI_ID_MIGRATE_INFO_UP_CPU    0x84000007
+#define PSCI_ID_SYSTEM_OFF                     0x84000008
+#define PSCI_ID_SYSTEM_RESET           0x84000009

With the KVM patches[1], this makes 4 copies of these defines in the kernel (and then QEMU has more). This needs to go into a common header under include/linux. Probably under uapi so QEMU can use. There is some sync of headers between the kernel and QEMU I think.

I agree we should have a common header, but I don't think this is uapi material. This is most definitely _not_ part of the user API, and it's from an external spec that we're not in control of -- I don't see why we should have to export a set of numbers forever because it happens to be marginally useful at this point in time.

Having the IDs handled by the kernel and those used by hypervisors also encourages people to validate the use of the correct IDs rather than everyone making the same mistake.

Quoted 11 lines

Quoted 5 lines

With the KVM patches[1], this makes 4 copies of these defines in the kernel (and then QEMU has more). This needs to go into a common header under include/linux. Probably under uapi so QEMU can use. There is some sync of headers between the kernel and QEMU I think.

I agree we should have a common header, but I don't think this is uapi material. This is most definitely _not_ part of the user API, and it's from an external spec that we're not in control of -- I don't see why we should have to export a set of numbers forever because it happens to be marginally useful at this point in time.

I mention uapi only in that it is expected to be stable (in an ABI sense) from kernel release to release, and I would assume that QEMU would only sync ABI stable headers. Someone familiar with the QEMU import process should comment on where this stuff should live.

The PSCI v0.2+ spec mandates specific values of Function IDs for ARM32 and ARM64. Use DT bindings of Function IDs only when using older versions. Use static values otherwise. This patch also prepares the code to easily use the ACPI API which is based off of PSCI v0.2+.

Signed-off-by Ashwin Chaugule <[email protected]>

---
 arch/arm/include/asm/psci.h   |  15 ++++++
 arch/arm/kernel/psci.c        | 110 +++++++++++++++++++++++++++++++++++++-----
 arch/arm64/include/asm/psci.h |  12 +++++
 arch/arm64/kernel/psci.c      | 106 +++++++++++++++++++++++++++++++++++-----
 4 files changed, 218 insertions(+), 25 deletions(-)

arch/arm/include/asm/psci.h +15 -0

index c4ae171..3f8ebf9 100644
@@ -17,6 +17,19 @@
 #define PSCI_POWER_STATE_TYPE_STANDBY		0
 #define PSCI_POWER_STATE_TYPE_POWER_DOWN	1
 
+/* PSCI Function ID's for ARM32 as per PSCI spec v0.2 */
+
+#define PSCI_ID_VERSION				0x84000000
+#define PSCI_ID_CPU_SUSPEND			0x84000001
+#define PSCI_ID_CPU_OFF				0x84000002
+#define PSCI_ID_CPU_ON				0x84000003
+#define PSCI_ID_AFFINITY_INFO		0x84000004
+#define PSCI_ID_CPU_MIGRATE			0x84000005
+#define PSCI_ID_MIGRATE_INFO_TYPE	0x84000006
+#define PSCI_ID_MIGRATE_INFO_UP_CPU	0x84000007
+#define PSCI_ID_SYSTEM_OFF			0x84000008
+#define PSCI_ID_SYSTEM_RESET		0x84000009
+
 struct psci_power_state {
 	u16	id;
 	u8	type;

@@ -36,9 +49,11 @@ extern struct smp_operations psci_smp_ops;
 
 #ifdef CONFIG_ARM_PSCI
 void psci_init(void);
+int psci_get_version(void);
 bool psci_smp_available(void);
 #else
 static inline void psci_init(void) { }
+static inline int psci_get_version(void) { }
 static inline bool psci_smp_available(void) { return false; }
 #endif
 

arch/arm/kernel/psci.c +97 -13

index 4693188..48e0b0a 100644
@@ -27,6 +27,7 @@
 struct psci_operations psci_ops;
 
 static int (*invoke_psci_fn)(u32, u32, u32, u32);
+typedef int (*psci_initcall_t)(const struct device_node *);
 
 enum psci_function {
 	PSCI_FN_CPU_SUSPEND,

@@ -110,6 +111,20 @@ static noinline int __invoke_psci_fn_smc(u32 function_id, u32 arg0, u32 arg1,
 	return function_id;
 }
 
+#define PSCI_VER_MAJOR_MASK		0xffff0000
+#define PSCI_VER_MINOR_MASK		0x0000ffff
+#define PSCI_VER_MAJOR_SHIFT	16
+
+static int psci_get_version(void)
+{
+	int err;
+	u32 fn;
+
+	fn = PSCI_ID_VERSION;
+	err = invoke_psci_fn(fn, 0, 0, 0);
+	return err;
+}
+
 static int psci_cpu_suspend(struct psci_power_state state,
 			    unsigned long entry_point)
 {

@@ -153,25 +168,65 @@ static int psci_migrate(unsigned long cpuid)
 	return psci_to_linux_errno(err);
 }
 
-static const struct of_device_id psci_of_match[] __initconst = {
-	{ .compatible = "arm,psci",	},
-	{},
-};
+/*
+ * PSCI Function ID's for v0.2+ are well defined so use
+ * static values.
+ */
+static int psci_static_init(struct device_node *np)
+{
+	const char *method;
+	int err = 0;
+
+	pr_info("probing for conduit method from DT.\n");
+
+	if (of_property_read_string(np, "method", &method)) {
+		pr_warn("missing \"method\" property\n");
+		err = -ENXIO;
+		goto out_put_node;
+	}
+
+	if (!strcmp("hvc", method)) {
+		invoke_psci_fn = __invoke_psci_fn_hvc;
+	} else if (!strcmp("smc", method)) {
+		invoke_psci_fn = __invoke_psci_fn_smc;
+	} else {
+		pr_warn("invalid \"method\" property: %s\n", method);
+		err = -EINVAL;
+		goto out_put_node;
+	}
 
-void __init psci_init(void)
+	pr_info("Using static PSCIv0.2+ function IDs\n");
+	psci_function_id[PSCI_FN_CPU_SUSPEND] = PSCI_ID_CPU_SUSPEND;
+	psci_ops.cpu_suspend = psci_cpu_suspend;
+
+	psci_function_id[PSCI_FN_CPU_OFF] = PSCI_ID_CPU_OFF;
+	psci_ops.cpu_off = psci_cpu_off;
+
+	psci_function_id[PSCI_FN_CPU_ON] = PSCI_ID_CPU_ON;
+	psci_ops.cpu_on = psci_cpu_on;
+
+	psci_function_id[PSCI_FN_MIGRATE] = PSCI_ID_CPU_MIGRATE;
+	psci_ops.migrate = psci_migrate;
+
+out_put_node:
+	of_node_put(np);
+	return err;
+}
+
+/*
+ * PSCI < v0.2 can override PSCI function ID's via DT.
+ */
+static int psci_of_init(struct device_node *np)
 {
-	struct device_node *np;
 	const char *method;
 	u32 id;
-
-	np = of_find_matching_node(NULL, psci_of_match);
-	if (!np)
-		return;
+	int err = 0;
 
 	pr_info("probing function IDs from device-tree\n");
 
 	if (of_property_read_string(np, "method", &method)) {
-		pr_warning("missing \"method\" property\n");
+		pr_warn("missing \"method\" property\n");
+		err = -EINVAL;
 		goto out_put_node;
 	}
 

@@ -180,7 +235,8 @@ void __init psci_init(void)
 	} else if (!strcmp("smc", method)) {
 		invoke_psci_fn = __invoke_psci_fn_smc;
 	} else {
-		pr_warning("invalid \"method\" property: %s\n", method);
+		pr_warn("invalid \"method\" property: %s\n", method);
+		err = -ENXIO;
 		goto out_put_node;
 	}
 

@@ -206,5 +262,33 @@ void __init psci_init(void)
 
 out_put_node:
 	of_node_put(np);
-	return;
+	return err;
+}
+
+static const struct of_device_id psci_of_match[] __initconst = {
+	{ .compatible = "arm,psci", .data = psci_of_init},
+	{ .compatible = "arm,psci-0.2", .data = psci_static_init},
+	{},
+};
+
+int __init psci_init(void)
+{
+	struct device_node *np;
+	const struct of_device_id *matched_np;
+	psci_initcall_t init_fn;
+	int ver = 0;
+
+	np = of_find_matching_node_and_match(NULL, psci_of_match, &matched_np);
+	if (!np)
+		return -ENODEV;
+
+	ver = psci_get_version();
+
+	pr_info("using static PSCIv%d.%d Function IDs\n",
+			(ver & PSCI_VER_MAJOR_MASK) >> PSCI_VER_MAJOR_SHIFT,
+			(ver & PSCI_VER_MINOR_MASK));
+
+
+	init_fn = (psci_initcall_t)matched_np->data;
+	return init_fn(np);
 }

arch/arm64/include/asm/psci.h +12 -0

index e5312ea..b72678f 100644
@@ -16,4 +16,16 @@
 
 int psci_init(void);
 
+/* PSCI Function ID's for ARM64 as per PSCI spec v0.2 */
+#define PSCI_ID_VERSION				0x84000000
+#define PSCI_ID_CPU_SUSPEND			0xc4000001
+#define PSCI_ID_CPU_OFF				0x84000002
+#define PSCI_ID_CPU_ON				0xc4000003
+#define PSCI_ID_AFFINITY_INFO		0xc4000004
+#define PSCI_ID_CPU_MIGRATE			0xc4000005
+#define PSCI_ID_MIGRATE_INFO_TYPE	0x84000006
+#define PSCI_ID_MIGRATE_INFO_UP_CPU	0xc4000007
+#define PSCI_ID_SYSTEM_OFF			0x84000008
+#define PSCI_ID_SYSTEM_RESET		0x84000009
+
 #endif /* __ASM_PSCI_H */

arch/arm64/kernel/psci.c +48 -5

index 4f97db3..d4cff4e 100644
@@ -45,12 +45,14 @@ struct psci_operations {
 static struct psci_operations psci_ops;
 
 static int (*invoke_psci_fn)(u64, u64, u64, u64);
+typedef int (*psci_initcall_t)(const struct device_node *);
 
 enum psci_function {
 	PSCI_FN_CPU_SUSPEND,
 	PSCI_FN_CPU_ON,
 	PSCI_FN_CPU_OFF,
 	PSCI_FN_MIGRATE,
+	PSCI_FN_AFFINITY_INFO,
 	PSCI_FN_MAX,
 };
 

@@ -128,6 +130,20 @@ static noinline int __invoke_psci_fn_smc(u64 function_id, u64 arg0, u64 arg1,
 	return function_id;
 }
 
+#define PSCI_VER_MAJOR_MASK		0xffff0000
+#define PSCI_VER_MINOR_MASK		0x0000ffff
+#define PSCI_VER_MAJOR_SHIFT	16
+
+static int psci_get_version(void)
+{
+	int err;
+	u32 fn;
+
+	fn = PSCI_ID_VERSION;
+	err = invoke_psci_fn(fn, 0, 0, 0);
+	return err;
+}
+
 static int psci_cpu_suspend(struct psci_power_state state,
 			    unsigned long entry_point)
 {

@@ -171,26 +187,64 @@ static int psci_migrate(unsigned long cpuid)
 	return psci_to_linux_errno(err);
 }
 
-static const struct of_device_id psci_of_match[] __initconst = {
-	{ .compatible = "arm,psci",	},
-	{},
-};
+/*
+ * PSCI Function ID's for v0.2+ are well defined so use
+ * static values.
+ */
+static int psci_static_init(struct device_node *np)
+{
+	const char *method;
+	int err = 0;
 
-int __init psci_init(void)
+	pr_info("probing for conduit method from DT.\n");
+
+	if (of_property_read_string(np, "method", &method)) {
+		pr_warn("missing \"method\" property\n");
+		err = -ENXIO;
+		goto out_put_node;
+	}
+
+	if (!strcmp("hvc", method)) {
+		invoke_psci_fn = __invoke_psci_fn_hvc;
+	} else if (!strcmp("smc", method)) {
+		invoke_psci_fn = __invoke_psci_fn_smc;
+	} else {
+		pr_warn("invalid \"method\" property: %s\n", method);
+		err = -EINVAL;
+		goto out_put_node;
+	}
+
+	pr_info("Using static PSCIv0.2+ function IDs\n");
+	psci_function_id[PSCI_FN_CPU_SUSPEND] = PSCI_ID_CPU_SUSPEND;
+	psci_ops.cpu_suspend = psci_cpu_suspend;
+
+	psci_function_id[PSCI_FN_CPU_OFF] = PSCI_ID_CPU_OFF;
+	psci_ops.cpu_off = psci_cpu_off;

The PSCI v0.2+ spec mandates specific values of Function IDs for ARM32 and ARM64. Use DT bindings of Function IDs only when using older versions. Use static values otherwise. This patch also prepares the code to easily use the ACPI API which is based off of PSCI v0.2+.

Signed-off-by Ashwin Chaugule <[email protected]>

---
 arch/arm/include/asm/psci.h   |  15 ++++++
 arch/arm/kernel/psci.c        | 110 +++++++++++++++++++++++++++++++++++++-----
 arch/arm64/include/asm/psci.h |  12 +++++
 arch/arm64/kernel/psci.c      | 106 +++++++++++++++++++++++++++++++++++-----
 4 files changed, 218 insertions(+), 25 deletions(-)

arch/arm/include/asm/psci.h +0 -0

index c4ae171..3f8ebf9 100644

arch/arm/include/asm/psci.h +14 -0

+
+#define PSCI_ID_VERSION				0x84000000
+#define PSCI_ID_CPU_SUSPEND			0x84000001
+#define PSCI_ID_CPU_OFF				0x84000002
+#define PSCI_ID_CPU_ON				0x84000003
+#define PSCI_ID_AFFINITY_INFO		0x84000004
+#define PSCI_ID_CPU_MIGRATE			0x84000005
+#define PSCI_ID_MIGRATE_INFO_TYPE	0x84000006
+#define PSCI_ID_MIGRATE_INFO_UP_CPU	0x84000007
+#define PSCI_ID_SYSTEM_OFF			0x84000008
+#define PSCI_ID_SYSTEM_RESET		0x84000009
+
 struct psci_power_state {
 	u16	id;
 	u8	type;

@@ -36,9 +49,11 @@ extern struct smp_operations psci_smp_ops;
 
 #ifdef CONFIG_ARM_PSCI
 void psci_init(void);
+int psci_get_version(void);
 bool psci_smp_available(void);
 #else
 static inline void psci_init(void) { }
+static inline int psci_get_version(void) { }
 static inline bool psci_smp_available(void) { return false; }
 #endif
 

arch/arm/kernel/psci.c +2 -0

index 4693188..48e0b0a 100644
@@ -27,6 +27,7 @@
 struct psci_operations psci_ops;
 
 static int (*invoke_psci_fn)(u32, u32, u32, u32);
+typedef int (*psci_initcall_t)(const struct device_node *);
 
 enum psci_function {
 	PSCI_FN_CPU_SUSPEND,

@@ -110,6 +111,20 @@ static noinline int __invoke_psci_fn_smc(u32 function_id, u32 arg0, u32 arg1,
 	return function_id;
 }
 
+#define PSCI_VER_MAJOR_MASK		0xffff0000

arch/arm/kernel/psci.c +22 -4

+	return err;
+}
+
 static int psci_cpu_suspend(struct psci_power_state state,
 			    unsigned long entry_point)
 {

@@ -153,25 +168,65 @@ static int psci_migrate(unsigned long cpuid)
 	return psci_to_linux_errno(err);
 }
 
-static const struct of_device_id psci_of_match[] __initconst = {
-	{ .compatible = "arm,psci",	},
-	{},
-};
+/*
+ * PSCI Function ID's for v0.2+ are well defined so use
+ * static values.
+ */
+static int psci_static_init(struct device_node *np)
+{
+	const char *method;
+	int err = 0;
+
+	pr_info("probing for conduit method from DT.\n");
+
+	if (of_property_read_string(np, "method", &method)) {
+		pr_warn("missing \"method\" property\n");
+		err = -ENXIO;
+		goto out_put_node;
+	}
+
+	if (!strcmp("hvc", method)) {
+		invoke_psci_fn = __invoke_psci_fn_hvc;

arch/arm/kernel/psci.c +6 -0

+	psci_function_id[PSCI_FN_CPU_SUSPEND] = PSCI_ID_CPU_SUSPEND;
+	psci_ops.cpu_suspend = psci_cpu_suspend;
+
+	psci_function_id[PSCI_FN_CPU_OFF] = PSCI_ID_CPU_OFF;
+	psci_ops.cpu_off = psci_cpu_off;
+

arch/arm/kernel/psci.c +8 -6

+
+/*
+ * PSCI < v0.2 can override PSCI function ID's via DT.
+ */
+static int psci_of_init(struct device_node *np)
 {
-	struct device_node *np;
 	const char *method;
 	u32 id;
-
-	np = of_find_matching_node(NULL, psci_of_match);
-	if (!np)
-		return;
+	int err = 0;
 
 	pr_info("probing function IDs from device-tree\n");
 
 	if (of_property_read_string(np, "method", &method)) {
-		pr_warning("missing \"method\" property\n");
+		pr_warn("missing \"method\" property\n");
+		err = -EINVAL;
 		goto out_put_node;
 	}
 

arch/arm/kernel/psci.c +15 -1

@@ -206,5 +262,33 @@ void __init psci_init(void)
 
 out_put_node:
 	of_node_put(np);
-	return;
+	return err;
+}
+
+static const struct of_device_id psci_of_match[] __initconst = {
+	{ .compatible = "arm,psci", .data = psci_of_init},
+	{ .compatible = "arm,psci-0.2", .data = psci_static_init},
+	{},
+};
+
+int __init psci_init(void)
+{
+	struct device_node *np;
+	const struct of_device_id *matched_np;
+	psci_initcall_t init_fn;
+	int ver = 0;

Quoted 2 lines

+/* PSCI Function ID's for ARM32 as per PSCI spec v0.2 */

Please drop the superfluous apostrophes, we aren't greengrocers [1].

%s/ID's/IDs/

Review

Quoted 2 lines

(quoted diff) +2 -0

+     fn = PSCI_ID_VERSION;
+     err = invoke_psci_fn(fn, 0, 0, 0);

Do we need fn here? Can't we pass PSCI_ID_VERSION directly?

arch/arm/kernel/psci.c static int psci_migrate(unsigned long cpuid) · line 198

Quoted 2 lines

arch/arm/kernel/psci.c +1 -1

-void __init psci_init(void)
+     pr_info("Using static PSCIv0.2+ function IDs\n");

How about "Using standard PSCI 0.2 function IDs"?

We're not using anything beyond PSCI 0.2 (yet), and "static" implies that there are dynamic IDs also.

Quoted 7 lines

arch/arm/kernel/psci.c +6 -0

+     psci_function_id[PSCI_FN_CPU_SUSPEND] = PSCI_ID_CPU_SUSPEND;
+     psci_ops.cpu_suspend = psci_cpu_suspend;
+
+     psci_function_id[PSCI_FN_CPU_OFF] = PSCI_ID_CPU_OFF;
+     psci_ops.cpu_off = psci_cpu_off;
+

arch/arm/kernel/psci.c static int psci_migrate(unsigned long cpuid) · line 214

Quoted 10 lines

arch/arm/kernel/psci.c +10 -0

+     psci_function_id[PSCI_FN_CPU_ON] = PSCI_ID_CPU_ON;
+     psci_ops.cpu_on = psci_cpu_on;
+
+     psci_function_id[PSCI_FN_MIGRATE] = PSCI_ID_CPU_MIGRATE;
+     psci_ops.migrate = psci_migrate;
+
+out_put_node:
+     of_node_put(np);
+     return err;
+}

I'd very much like to see us use AFFINITY_INFO from the start, or we've got a racy down path (as we have for all PSCI implementations prior to 0.2), and implementors are likely to skip implementing it if Linux seems to work, so we'll never be able to rely on it.

Additionally it'd be nice to check what MIGRATE_INFO_TYPE returns. If it returns a value other than 2 (MP or not present), then there's some additional work that we need to perform around a down path or we might not be able to shut down some CPUs.

Quoted 25 lines

arch/arm/kernel/psci.c +8 -6

+
+/*
+ * PSCI < v0.2 can override PSCI function ID's via DT.
+ */
+static int psci_of_init(struct device_node *np)
 {
-     struct device_node *np;
      const char *method;
      u32 id;
-
-     np = of_find_matching_node(NULL, psci_of_match);
-     if (!np)
-             return;
+     int err = 0;
 
      pr_info("probing function IDs from device-tree\n");
 
      if (of_property_read_string(np, "method", &method)) {
-             pr_warning("missing \"method\" property\n");
+             pr_warn("missing \"method\" property\n");
+             err = -EINVAL;
              goto out_put_node;
      }

arch/arm/kernel/psci.c void __init psci_init(void) · line 241

Quoted 9 lines

arch/arm/kernel/psci.c +2 -1

@@ -180,7 +235,8 @@ void __init psci_init(void)
      } else if (!strcmp("smc", method)) {
              invoke_psci_fn = __invoke_psci_fn_smc;
      } else {
-             pr_warning("invalid \"method\" property: %s\n", method);
+             pr_warn("invalid \"method\" property: %s\n", method);
+             err = -ENXIO;
              goto out_put_node;
      }

We should definitely factor this into a helper rather than duplicating it.

Hi Mark,

Quoted 1 line · Mark Rutland

Quoted 1 line

Quoted 5 lines

Quoted 1 line

+/* PSCI Function ID's for ARM32 as per PSCI spec v0.2 */

Please drop the superfluous apostrophes, we aren't greengrocers [1].

%s/ID's/IDs/

Ok. Will fix all the uncouth bacilli. ;)

Quoted 22 lines

Quoted 6 lines

arch/arm/kernel/psci.c +6 -0

+     psci_function_id[PSCI_FN_CPU_SUSPEND] = PSCI_ID_CPU_SUSPEND;
+     psci_ops.cpu_suspend = psci_cpu_suspend;
+
+     psci_function_id[PSCI_FN_CPU_OFF] = PSCI_ID_CPU_OFF;
+     psci_ops.cpu_off = psci_cpu_off;
+

arch/arm/kernel/psci.c static int psci_migrate(unsigned long cpuid) · line 214

Quoted 10 lines

arch/arm/kernel/psci.c +10 -0

+     psci_function_id[PSCI_FN_CPU_ON] = PSCI_ID_CPU_ON;
+     psci_ops.cpu_on = psci_cpu_on;
+
+     psci_function_id[PSCI_FN_MIGRATE] = PSCI_ID_CPU_MIGRATE;
+     psci_ops.migrate = psci_migrate;
+
+out_put_node:
+     of_node_put(np);
+     return err;
+}

I'd very much like to see us use AFFINITY_INFO from the start, or we've got a racy down path (as we have for all PSCI implementations prior to 0.2), and implementors are likely to skip implementing it if Linux seems to work, so we'll never be able to rely on it.

Quoted 4 lines

Additionally it'd be nice to check what MIGRATE_INFO_TYPE returns. If it returns a value other than 2 (MP or not present), then there's some additional work that we need to perform around a down path or we might not be able to shut down some CPUs.

The main intention of this patch is to separate function ID detection depending on PSCI versions.
So, I think the additional functionality of AFFINITY_INFO and MIGRATE_INFO_TYPE should go in as separate patches. Do you agree?

Quoted 4 lines

The main intention of this patch is to separate function ID detection depending on PSCI versions.
So, I think the additional functionality of AFFINITY_INFO and MIGRATE_INFO_TYPE should go in as separate patches. Do you agree?

Unfortunately this has the side effect of seemingly adding support for PSCI 0.2 while not actually doing so. I fear that people will begin using the "arm,psci-0.2" string before we end up implementing code using the other required functionality, and it will turn out we can't make use of any of it, because it will cause someone's firmware to blow up.