[7/7] drivers: firmware: psci: Announce support for OS initiated suspend mode

Message ID 20190228135919.3747-8-ulf.hansson@linaro.org
State Superseded
Headers show
Series
  • drivers: firmware: psci: Some cleanup and refactoring
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Commit Message

Ulf Hansson Feb. 28, 2019, 1:59 p.m.
PSCI firmware v1.0+, supports two different modes for CPU_SUSPEND. The
Platform Coordinated mode, which is the default and mandatory mode, while
support for the OS initiated (OSI) mode is optional.

In some cases it's interesting for the user/developer to know if the OSI
mode is supported by the PSCI FW. Therefore, let's print a message to the
log, if that is the case.

Cc: Lina Iyer <ilina@codeaurora.org>
Co-developed-by: Lina Iyer <lina.iyer@linaro.org>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

---
 drivers/firmware/psci/psci.c | 21 ++++++++++++++++++++-
 include/uapi/linux/psci.h    |  5 +++++
 2 files changed, 25 insertions(+), 1 deletion(-)

-- 
2.17.1

Comments

Stephen Boyd March 1, 2019, 5:28 p.m. | #1
Quoting Ulf Hansson (2019-02-28 05:59:19)
> PSCI firmware v1.0+, supports two different modes for CPU_SUSPEND. The

> Platform Coordinated mode, which is the default and mandatory mode, while

> support for the OS initiated (OSI) mode is optional.

> 

> In some cases it's interesting for the user/developer to know if the OSI

> mode is supported by the PSCI FW. Therefore, let's print a message to the

> log, if that is the case.


I don't see anything wrong with the patch besides the potential for the
logs to wrap and the informational message to be lost, but would it be
possible to express the PSCI features that are supported in sysfs at
/sys/firmware/psci/ somehow? It may be useful for a user to know that
their firmware has PSCI support and that it has a certain set of
features available, like OSI vs. PC, or both. I don't know of any use
that userspace would have though, besides maybe the CPU state residency
counters being used by some sort of statistics collecting program or
just plain knowing that certain PSCI features are present, so perhaps it
could just be done in debugfs for now until a real user exists.

Patch

diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
index 14d25b54b9f2..417d43886948 100644
--- a/drivers/firmware/psci/psci.c
+++ b/drivers/firmware/psci/psci.c
@@ -95,6 +95,11 @@  static inline bool psci_has_ext_power_state(void)
 				PSCI_1_0_FEATURES_CPU_SUSPEND_PF_MASK;
 }
 
+static inline bool psci_has_osi_support(void)
+{
+	return psci_cpu_suspend_feature & PSCI_1_0_OS_INITIATED;
+}
+
 static inline bool psci_power_state_loses_context(u32 state)
 {
 	const u32 mask = psci_has_ext_power_state() ?
@@ -659,10 +664,24 @@  static int __init psci_0_1_init(struct device_node *np)
 	return 0;
 }
 
+static int __init psci_1_0_init(struct device_node *np)
+{
+	int err;
+
+	err = psci_0_2_init(np);
+	if (err)
+		return err;
+
+	if (psci_has_osi_support())
+		pr_info("OSI mode supported.\n");
+
+	return 0;
+}
+
 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},
-	{ .compatible = "arm,psci-1.0",	.data = psci_0_2_init},
+	{ .compatible = "arm,psci-1.0",	.data = psci_1_0_init},
 	{},
 };
 
diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
index b3bcabe380da..581f72085c33 100644
--- a/include/uapi/linux/psci.h
+++ b/include/uapi/linux/psci.h
@@ -49,6 +49,7 @@ 
 
 #define PSCI_1_0_FN_PSCI_FEATURES		PSCI_0_2_FN(10)
 #define PSCI_1_0_FN_SYSTEM_SUSPEND		PSCI_0_2_FN(14)
+#define PSCI_1_0_FN_SET_SUSPEND_MODE		PSCI_0_2_FN(15)
 
 #define PSCI_1_0_FN64_SYSTEM_SUSPEND		PSCI_0_2_FN64(14)
 
@@ -97,6 +98,10 @@ 
 #define PSCI_1_0_FEATURES_CPU_SUSPEND_PF_MASK	\
 			(0x1 << PSCI_1_0_FEATURES_CPU_SUSPEND_PF_SHIFT)
 
+#define PSCI_1_0_OS_INITIATED			BIT(0)
+#define PSCI_1_0_SUSPEND_MODE_PC		0
+#define PSCI_1_0_SUSPEND_MODE_OSI		1
+
 /* PSCI return values (inclusive of all PSCI versions) */
 #define PSCI_RET_SUCCESS			0
 #define PSCI_RET_NOT_SUPPORTED			-1