diff mbox

[v3,1/3] PSCI: Add initial support for PSCIv0.2 functions

Message ID 1395955430-26050-2-git-send-email-ashwin.chaugule@linaro.org (mailing list archive)
State New, archived
Headers show

Commit Message

Ashwin Chaugule March 27, 2014, 9:23 p.m. UTC
The PSCIv0.2 spec defines standard values of function IDs
and introduces a few new functions. Detect version of PSCI
and appropriately select the right PSCI functions.

Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
---
 arch/arm/include/asm/psci.h |   7 +-
 arch/arm/kernel/psci.c      | 151 +++++++++++++++++++++++++++++++++++++------
 arch/arm64/kernel/psci.c    | 154 +++++++++++++++++++++++++++++++++++++-------
 include/uapi/linux/psci.h   |  40 ++++++++++++
 4 files changed, 307 insertions(+), 45 deletions(-)
 create mode 100644 include/uapi/linux/psci.h

Comments

Rob Herring March 28, 2014, 1:54 p.m. UTC | #1
On Thu, Mar 27, 2014 at 4:23 PM, Ashwin Chaugule
<ashwin.chaugule@linaro.org> wrote:
> The PSCIv0.2 spec defines standard values of function IDs
> and introduces a few new functions. Detect version of PSCI
> and appropriately select the right PSCI functions.

Looks pretty good. A few minor things below.

[snip]

> @@ -110,6 +109,21 @@ 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
> +#define PSCI_VER_MAJOR(ver)            \
> +       ((ver & PSCI_VER_MAJOR_MASK) >> PSCI_VER_MAJOR_SHIFT)
> +#define PSCI_VER_MINOR(ver)            (ver & PSCI_VER_MINOR_MASK)

This can go in the header.

[snip]

> +       ver = psci_get_version();
> +
> +       pr_info("PSCIv%d.%d detected in firmware.\n", PSCI_VER_MAJOR(ver),
> +                       PSCI_VER_MINOR(ver));
> +
> +       if (PSCI_VER_MAJOR(ver) == 0 && PSCI_VER_MINOR(ver) < 2) {

So we want to allow 0.3, but not 1.x? I think we want to allow any
later version. Later versions either have to be backward's compatible
with 0.2 or have to not have "arm,psci-0.2" compatible string.

Does this work if ver is an error value? We may have implementations
that failed to implement this function (which should not be ignored
for now).

>                 err = -EINVAL;
> +               pr_err("Conflicting PSCI version detected.\n");
>                 goto out_put_node;
>         }

[snip]

> diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
> new file mode 100644
> index 0000000..c523051
> --- /dev/null
> +++ b/include/uapi/linux/psci.h
> @@ -0,0 +1,40 @@
> +/*
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License as published by
> + *  the Free Software Foundation; either version 2 of the License, or
> + *  (at your option) any later version.
> + *
> + *  This program is distributed in the hope that it will be useful,
> + *  but WITHOUT ANY WARRANTY; without even the implied warranty of
> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + *  GNU General Public License for more details.
> + *
> + *     Copyright (C) 2014, Ashwin Chaugule <ashwin.chaugule@linaro.org>

I believe this should be:

Copyright (C) 2014 Linaro Ltd.
Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>

And typically the copyright is placed above the license.

> + */
> +
> +#ifndef _UAPI_LINUX_PSCI_H
> +#define _UAPI_LINUX_PSCI_H
> +
> +/* PSCI Function IDs as per PSCI spec v0.2 */
> +#define PSCI_ID_VERSION                                        0x84000000
> +#define PSCI_ID_CPU_SUSPEND_32                 0x84000001
> +#define PSCI_ID_CPU_SUSPEND_64                 0xc4000001
> +#define PSCI_ID_CPU_OFF                                        0x84000002
> +#define PSCI_ID_CPU_ON_32                              0x84000003
> +#define PSCI_ID_CPU_ON_64                              0xC4000003
> +#define PSCI_ID_AFFINITY_INFO_32               0x84000004
> +#define PSCI_ID_AFFINITY_INFO_64               0xC4000004
> +#define PSCI_ID_CPU_MIGRATE_32                 0x84000005
> +#define PSCI_ID_CPU_MIGRATE_64                 0xc4000005
> +#define PSCI_ID_MIGRATE_INFO_TYPE              0x84000006
> +#define PSCI_ID_MIGRATE_INFO_UP_CPU_32 0x84000007
> +#define PSCI_ID_MIGRATE_INFO_UP_CPU_64 0xc4000007
> +#define PSCI_ID_SYSTEM_OFF                             0x84000008
> +#define PSCI_ID_SYSTEM_RESET                   0x84000009
> +
> +#define PSCI_RET_SUCCESS               0
> +#define PSCI_RET_EOPNOTSUPP            -1
> +#define PSCI_RET_EINVAL                        -2
> +#define PSCI_RET_EPERM                 -3

Please fill out all error codes.

> +
> +#endif /* _UAPI_LINUX_PSCI_H */
> --
> 1.8.3.2
>
Ashwin Chaugule March 28, 2014, 3 p.m. UTC | #2
Hi Rob,

On 28 March 2014 09:54, Rob Herring <rob.herring@linaro.org> wrote:

>> +#define PSCI_VER_MAJOR_MASK            0xffff0000
>> +#define PSCI_VER_MINOR_MASK            0x0000ffff
>> +#define PSCI_VER_MAJOR_SHIFT   16
>> +#define PSCI_VER_MAJOR(ver)            \
>> +       ((ver & PSCI_VER_MAJOR_MASK) >> PSCI_VER_MAJOR_SHIFT)
>> +#define PSCI_VER_MINOR(ver)            (ver & PSCI_VER_MINOR_MASK)
>
> This can go in the header.

Will do.

>
> [snip]
>
>> +       ver = psci_get_version();
>> +
>> +       pr_info("PSCIv%d.%d detected in firmware.\n", PSCI_VER_MAJOR(ver),
>> +                       PSCI_VER_MINOR(ver));
>> +
>> +       if (PSCI_VER_MAJOR(ver) == 0 && PSCI_VER_MINOR(ver) < 2) {
>
> So we want to allow 0.3, but not 1.x? I think we want to allow any
> later version. Later versions either have to be backward's compatible
> with 0.2 or have to not have "arm,psci-0.2" compatible string.

If its 1.x, it should still go through? Should only fail for 0.1 or 0.0.

>
> Does this work if ver is an error value? We may have implementations
> that failed to implement this function (which should not be ignored
> for now).

True. What is a good err value to check for? negative values?

One would hope implementations would return (-7) NOT_PRESENT, but it
could also be garbage?

>> + *
>> + *     Copyright (C) 2014, Ashwin Chaugule <ashwin.chaugule@linaro.org>
>
> I believe this should be:
>
> Copyright (C) 2014 Linaro Ltd.
> Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
>
> And typically the copyright is placed above the license.

Ok.

>> +
>> +#define PSCI_RET_SUCCESS               0
>> +#define PSCI_RET_EOPNOTSUPP            -1
>> +#define PSCI_RET_EINVAL                        -2
>> +#define PSCI_RET_EPERM                 -3
>
> Please fill out all error codes.
>

Ok, I see the return codes table. Will add all of it.

Cheers,
Ashwin
Charles Garcia-Tobin March 28, 2014, 3:40 p.m. UTC | #3
> -----Original Message-----
> From: linaro-acpi-bounces@lists.linaro.org [mailto:linaro-acpi-
> bounces@lists.linaro.org] On Behalf Of Ashwin Chaugule
> Sent: 28 March 2014 15:00
> To: rob.herring@linaro.org
> Cc: Anup Patel; Patch Tracking; Marc Zyngier; linaro-acpi;
linux-arm-kernel;
> Christoffer Dall
> Subject: Re: [Linaro-acpi] [PATCH v3 1/3] PSCI: Add initial support for
PSCIv0.2
> functions
> 
> Hi Rob,
> 
> On 28 March 2014 09:54, Rob Herring <rob.herring@linaro.org> wrote:
> 
> >> +#define PSCI_VER_MAJOR_MASK            0xffff0000
> >> +#define PSCI_VER_MINOR_MASK            0x0000ffff
> >> +#define PSCI_VER_MAJOR_SHIFT   16
> >> +#define PSCI_VER_MAJOR(ver)            \
> >> +       ((ver & PSCI_VER_MAJOR_MASK) >> PSCI_VER_MAJOR_SHIFT)
> >> +#define PSCI_VER_MINOR(ver)            (ver & PSCI_VER_MINOR_MASK)
> >
> > This can go in the header.
> 
> Will do.
> 
> >
> > [snip]
> >
> >> +       ver = psci_get_version();
> >> +
> >> +       pr_info("PSCIv%d.%d detected in firmware.\n",
PSCI_VER_MAJOR(ver),
> >> +                       PSCI_VER_MINOR(ver));
> >> +
> >> +       if (PSCI_VER_MAJOR(ver) == 0 && PSCI_VER_MINOR(ver) < 2) {
> >
> > So we want to allow 0.3, but not 1.x? I think we want to allow any
> > later version. Later versions either have to be backward's compatible
> > with 0.2 or have to not have "arm,psci-0.2" compatible string.
> 
> If its 1.x, it should still go through? Should only fail for 0.1 or 0.0.
> 
> >
> > Does this work if ver is an error value? We may have implementations
> > that failed to implement this function (which should not be ignored
> > for now).
> 
> True. What is a good err value to check for? negative values?
> 
> One would hope implementations would return (-7) NOT_PRESENT, but it
> could also be garbage?

So from v0.2 PSCI_VERSION is compulsory. It has to be implemented. If a
function is not implemented it must return NOT_SUPPORTED(-1)

Cheers

Charles

>
> >> + *
> >> + *     Copyright (C) 2014, Ashwin Chaugule
<ashwin.chaugule@linaro.org>
> >
> > I believe this should be:
> >
> > Copyright (C) 2014 Linaro Ltd.
> > Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
> >
> > And typically the copyright is placed above the license.
> 
> Ok.
> 
> >> +
> >> +#define PSCI_RET_SUCCESS               0
> >> +#define PSCI_RET_EOPNOTSUPP            -1
> >> +#define PSCI_RET_EINVAL                        -2
> >> +#define PSCI_RET_EPERM                 -3
> >
> > Please fill out all error codes.
> >
> 
> Ok, I see the return codes table. Will add all of it.
> 
> Cheers,
> Ashwin
> 
> _______________________________________________
> Linaro-acpi mailing list
> Linaro-acpi@lists.linaro.org
> http://lists.linaro.org/mailman/listinfo/linaro-acpi
diff mbox

Patch

diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h
index c4ae171..b93e34a 100644
--- a/arch/arm/include/asm/psci.h
+++ b/arch/arm/include/asm/psci.h
@@ -29,16 +29,19 @@  struct psci_operations {
 	int (*cpu_off)(struct psci_power_state state);
 	int (*cpu_on)(unsigned long cpuid, unsigned long entry_point);
 	int (*migrate)(unsigned long cpuid);
+	int (*affinity_info)(unsigned long target_affinity,
+			unsigned long lowest_affinity_level);
+	int (*migrate_info_type)(void);
 };
 
 extern struct psci_operations psci_ops;
 extern struct smp_operations psci_smp_ops;
 
 #ifdef CONFIG_ARM_PSCI
-void psci_init(void);
+int psci_init(void);
 bool psci_smp_available(void);
 #else
-static inline void psci_init(void) { }
+static inline int psci_init(void) { }
 static inline bool psci_smp_available(void) { return false; }
 #endif
 
diff --git a/arch/arm/kernel/psci.c b/arch/arm/kernel/psci.c
index 4693188..e7cc62e 100644
--- a/arch/arm/kernel/psci.c
+++ b/arch/arm/kernel/psci.c
@@ -17,6 +17,7 @@ 
 
 #include <linux/init.h>
 #include <linux/of.h>
+#include <uapi/linux/psci.h>
 
 #include <asm/compiler.h>
 #include <asm/errno.h>
@@ -27,22 +28,20 @@ 
 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,
 	PSCI_FN_CPU_ON,
 	PSCI_FN_CPU_OFF,
 	PSCI_FN_MIGRATE,
+	PSCI_FN_AFFINITY_INFO,
+	PSCI_FN_MIGRATE_INFO_TYPE,
 	PSCI_FN_MAX,
 };
 
 static u32 psci_function_id[PSCI_FN_MAX];
 
-#define PSCI_RET_SUCCESS		0
-#define PSCI_RET_EOPNOTSUPP		-1
-#define PSCI_RET_EINVAL			-2
-#define PSCI_RET_EPERM			-3
-
 static int psci_to_linux_errno(int errno)
 {
 	switch (errno) {
@@ -110,6 +109,21 @@  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
+#define PSCI_VER_MAJOR(ver)		\
+	((ver & PSCI_VER_MAJOR_MASK) >> PSCI_VER_MAJOR_SHIFT)
+#define PSCI_VER_MINOR(ver)		(ver & PSCI_VER_MINOR_MASK)
+
+static int psci_get_version(void)
+{
+	int err;
+
+	err = invoke_psci_fn(PSCI_ID_VERSION, 0, 0, 0);
+	return err;
+}
+
 static int psci_cpu_suspend(struct psci_power_state state,
 			    unsigned long entry_point)
 {
@@ -153,26 +167,36 @@  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",	},
-	{},
-};
+static int psci_affinity_info(unsigned long target_affinity,
+		unsigned long lowest_affinity_level)
+{
+	int err;
+	u32 fn;
 
-void __init psci_init(void)
+	fn = psci_function_id[PSCI_FN_AFFINITY_INFO];
+	err = invoke_psci_fn(fn, target_affinity, lowest_affinity_level, 0);
+	return err;
+}
+
+static int psci_migrate_info_type(void)
 {
-	struct device_node *np;
-	const char *method;
-	u32 id;
+	int err;
+	u32 fn;
 
-	np = of_find_matching_node(NULL, psci_of_match);
-	if (!np)
-		return;
+	fn = psci_function_id[PSCI_FN_MIGRATE_INFO_TYPE];
+	err = invoke_psci_fn(fn, 0, 0, 0);
+	return err;
+}
 
-	pr_info("probing function IDs from device-tree\n");
+static int get_set_conduit_method(struct device_node *np)
+{
+	const char *method;
+
+	pr_info("probing for conduit method from DT.\n");
 
 	if (of_property_read_string(np, "method", &method)) {
-		pr_warning("missing \"method\" property\n");
-		goto out_put_node;
+		pr_warn("missing \"method\" property\n");
+		return -ENXIO;
 	}
 
 	if (!strcmp("hvc", method)) {
@@ -180,10 +204,75 @@  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);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+/*
+ * PSCI Function IDs for v0.2+ are well defined so use
+ * standard values.
+ */
+static int psci_0_2_init(struct device_node *np)
+{
+	int err, ver;
+
+	err = get_set_conduit_method(np);
+
+	if (err)
+		goto out_put_node;
+
+	ver = psci_get_version();
+
+	pr_info("PSCIv%d.%d detected in firmware.\n", PSCI_VER_MAJOR(ver),
+			PSCI_VER_MINOR(ver));
+
+	if (PSCI_VER_MAJOR(ver) == 0 && PSCI_VER_MINOR(ver) < 2) {
+		err = -EINVAL;
+		pr_err("Conflicting PSCI version detected.\n");
 		goto out_put_node;
 	}
 
+	pr_info("Using standard PSCI v0.2 function IDs\n");
+	psci_function_id[PSCI_FN_CPU_SUSPEND] = PSCI_ID_CPU_SUSPEND_32;
+	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_32;
+	psci_ops.cpu_on = psci_cpu_on;
+
+	psci_function_id[PSCI_FN_MIGRATE] = PSCI_ID_CPU_MIGRATE_32;
+	psci_ops.migrate = psci_migrate;
+
+	psci_function_id[PSCI_FN_AFFINITY_INFO] = PSCI_ID_AFFINITY_INFO_32;
+	psci_ops.affinity_info = psci_affinity_info;
+
+	psci_function_id[PSCI_FN_MIGRATE_INFO_TYPE] = PSCI_ID_MIGRATE_INFO_TYPE;
+	psci_ops.migrate_info_type = psci_migrate_info_type;
+
+out_put_node:
+	of_node_put(np);
+	return err;
+}
+
+/*
+ * PSCI < v0.2 get PSCI Function IDs via DT.
+ */
+static int psci_0_1_init(struct device_node *np)
+{
+	u32 id;
+	int err;
+
+	err = get_set_conduit_method(np);
+
+	if (err)
+		goto out_put_node;
+
+	pr_info("Using PSCI v0.1 Function IDs from DT\n");
+
 	if (!of_property_read_u32(np, "cpu_suspend", &id)) {
 		psci_function_id[PSCI_FN_CPU_SUSPEND] = id;
 		psci_ops.cpu_suspend = psci_cpu_suspend;
@@ -206,5 +295,25 @@  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_0_1_init},
+	{ .compatible = "arm,psci-0.2", .data = psci_0_2_init},
+	{},
+};
+
+int __init psci_init(void)
+{
+	struct device_node *np;
+	const struct of_device_id *matched_np;
+	psci_initcall_t init_fn;
+
+	np = of_find_matching_node_and_match(NULL, psci_of_match, &matched_np);
+	if (!np)
+		return -ENODEV;
+
+	init_fn = (psci_initcall_t)matched_np->data;
+	return init_fn(np);
 }
diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
index 4f97db3..6b6590d 100644
--- a/arch/arm64/kernel/psci.c
+++ b/arch/arm64/kernel/psci.c
@@ -18,6 +18,7 @@ 
 #include <linux/init.h>
 #include <linux/of.h>
 #include <linux/smp.h>
+#include <uapi/linux/psci.h>
 
 #include <asm/compiler.h>
 #include <asm/cpu_ops.h>
@@ -40,27 +41,28 @@  struct psci_operations {
 	int (*cpu_off)(struct psci_power_state state);
 	int (*cpu_on)(unsigned long cpuid, unsigned long entry_point);
 	int (*migrate)(unsigned long cpuid);
+	int (*affinity_info)(unsigned long target_affinity,
+			unsigned long lowest_affinity_level);
+	int (*migrate_info_type)(void);
 };
 
 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_MIGRATE_INFO_TYPE,
 	PSCI_FN_MAX,
 };
 
 static u32 psci_function_id[PSCI_FN_MAX];
 
-#define PSCI_RET_SUCCESS		0
-#define PSCI_RET_EOPNOTSUPP		-1
-#define PSCI_RET_EINVAL			-2
-#define PSCI_RET_EPERM			-3
-
 static int psci_to_linux_errno(int errno)
 {
 	switch (errno) {
@@ -128,6 +130,21 @@  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
+#define PSCI_VER_MAJOR(ver)		\
+	((ver & PSCI_VER_MAJOR_MASK) >> PSCI_VER_MAJOR_SHIFT)
+#define PSCI_VER_MINOR(ver)		(ver & PSCI_VER_MINOR_MASK)
+
+static int psci_get_version(void)
+{
+	int err;
+
+	err = invoke_psci_fn(PSCI_ID_VERSION, 0, 0, 0);
+	return err;
+}
+
 static int psci_cpu_suspend(struct psci_power_state state,
 			    unsigned long entry_point)
 {
@@ -171,28 +188,36 @@  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",	},
-	{},
-};
+static int psci_affinity_info(unsigned long target_affinity,
+		unsigned long lowest_affinity_level)
+{
+	int err;
+	u32 fn;
 
-int __init psci_init(void)
+	fn = psci_function_id[PSCI_FN_AFFINITY_INFO];
+	err = invoke_psci_fn(fn, target_affinity, lowest_affinity_level, 0);
+	return err;
+}
+
+static int psci_migrate_info_type(void)
 {
-	struct device_node *np;
-	const char *method;
-	u32 id;
-	int err = 0;
+	int err;
+	u32 fn;
 
-	np = of_find_matching_node(NULL, psci_of_match);
-	if (!np)
-		return -ENODEV;
+	fn = psci_function_id[PSCI_FN_MIGRATE_INFO_TYPE];
+	err = invoke_psci_fn(fn, 0, 0, 0);
+	return err;
+}
 
-	pr_info("probing function IDs from device-tree\n");
+static int get_set_conduit_method(struct device_node *np)
+{
+	const char *method;
+
+	pr_info("probing for conduit method from DT.\n");
 
 	if (of_property_read_string(np, "method", &method)) {
-		pr_warning("missing \"method\" property\n");
-		err = -ENXIO;
-		goto out_put_node;
+		pr_warn("missing \"method\" property\n");
+		return -ENXIO;
 	}
 
 	if (!strcmp("hvc", method)) {
@@ -200,11 +225,75 @@  int __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);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+/*
+ * PSCI Function IDs for v0.2+ are well defined so use
+ * standard values.
+ */
+static int psci_0_2_init(struct device_node *np)
+{
+	int err, ver;
+
+	err = get_set_conduit_method(np);
+
+	if (err)
+		goto out_put_node;
+
+	ver = psci_get_version();
+
+	pr_info("PSCIv%d.%d detected in firmware.\n", PSCI_VER_MAJOR(ver),
+			PSCI_VER_MINOR(ver));
+
+	if (PSCI_VER_MAJOR(ver) == 0 && PSCI_VER_MINOR(ver) < 2) {
 		err = -EINVAL;
+		pr_err("Conflicting PSCI version detected.\n");
 		goto out_put_node;
 	}
 
+	pr_info("Using standard PSCI v0.2 function IDs\n");
+	psci_function_id[PSCI_FN_CPU_SUSPEND] = PSCI_ID_CPU_SUSPEND_64;
+	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_64;
+	psci_ops.cpu_on = psci_cpu_on;
+
+	psci_function_id[PSCI_FN_MIGRATE] = PSCI_ID_CPU_MIGRATE_64;
+	psci_ops.migrate = psci_migrate;
+
+	psci_function_id[PSCI_FN_AFFINITY_INFO] = PSCI_ID_AFFINITY_INFO_64;
+	psci_ops.affinity_info = psci_affinity_info;
+
+	psci_function_id[PSCI_FN_MIGRATE_INFO_TYPE] = PSCI_ID_MIGRATE_INFO_TYPE;
+	psci_ops.migrate_info_type = psci_migrate_info_type;
+
+out_put_node:
+	of_node_put(np);
+	return err;
+}
+
+/*
+ * PSCI < v0.2 get PSCI Function IDs via DT.
+ */
+static int psci_0_1_init(struct device_node *np)
+{
+	u32 id;
+	int err;
+
+	err = get_set_conduit_method(np);
+
+	if (err)
+		goto out_put_node;
+
+	pr_info("Using PSCI v0.1 Function IDs from DT\n");
+
 	if (!of_property_read_u32(np, "cpu_suspend", &id)) {
 		psci_function_id[PSCI_FN_CPU_SUSPEND] = id;
 		psci_ops.cpu_suspend = psci_cpu_suspend;
@@ -230,6 +319,27 @@  out_put_node:
 	return err;
 }
 
+static const struct of_device_id psci_of_match[] __initconst = {
+	{ .compatible = "arm,psci",	.data = psci_0_1_init},
+	{ .compatible = "arm,psci-0.2",	.data = psci_0_2_init},
+	{},
+};
+
+int __init psci_init(void)
+{
+	struct device_node *np;
+	const struct of_device_id *matched_np;
+	psci_initcall_t init_fn;
+
+	np = of_find_matching_node_and_match(NULL, psci_of_match, &matched_np);
+
+	if (!np)
+		return -ENODEV;
+
+	init_fn = (psci_initcall_t)matched_np->data;
+	return init_fn(np);
+}
+
 #ifdef CONFIG_SMP
 
 static int __init cpu_psci_cpu_init(struct device_node *dn, unsigned int cpu)
diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
new file mode 100644
index 0000000..c523051
--- /dev/null
+++ b/include/uapi/linux/psci.h
@@ -0,0 +1,40 @@ 
+/*
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *	Copyright (C) 2014, Ashwin Chaugule <ashwin.chaugule@linaro.org>
+ */
+
+#ifndef _UAPI_LINUX_PSCI_H
+#define _UAPI_LINUX_PSCI_H
+
+/* PSCI Function IDs as per PSCI spec v0.2 */
+#define PSCI_ID_VERSION					0x84000000
+#define PSCI_ID_CPU_SUSPEND_32			0x84000001
+#define PSCI_ID_CPU_SUSPEND_64			0xc4000001
+#define PSCI_ID_CPU_OFF					0x84000002
+#define PSCI_ID_CPU_ON_32				0x84000003
+#define PSCI_ID_CPU_ON_64				0xC4000003
+#define PSCI_ID_AFFINITY_INFO_32		0x84000004
+#define PSCI_ID_AFFINITY_INFO_64		0xC4000004
+#define PSCI_ID_CPU_MIGRATE_32			0x84000005
+#define PSCI_ID_CPU_MIGRATE_64			0xc4000005
+#define PSCI_ID_MIGRATE_INFO_TYPE		0x84000006
+#define PSCI_ID_MIGRATE_INFO_UP_CPU_32	0x84000007
+#define PSCI_ID_MIGRATE_INFO_UP_CPU_64	0xc4000007
+#define PSCI_ID_SYSTEM_OFF				0x84000008
+#define PSCI_ID_SYSTEM_RESET			0x84000009
+
+#define PSCI_RET_SUCCESS		0
+#define PSCI_RET_EOPNOTSUPP		-1
+#define PSCI_RET_EINVAL			-2
+#define PSCI_RET_EPERM			-3
+
+#endif /* _UAPI_LINUX_PSCI_H */