[Patch v4 1/2] arm: kernel: Add SMC structure parameter

From: Andy Gross
Date: Thu Jan 19 2017 - 12:30:25 EST


This patch adds a quirk parameter to the arm_smccc_smc call. The quirk
structure allows for specialized SMC operations due to SoC specific
requirements. The current arm_smccc_smc is renamed and macros are used
instead to specify the standard arm_smccc_smc or the arm_smccc_smc_quirk
function.

This patch and partial implementation was suggested by Will Deacon.

Signed-off-by: Andy Gross <andy.gross@xxxxxxxxxx>
Reviewed-by: Will Deacon <will.deacon@xxxxxxx>
---
arch/arm/kernel/armksyms.c | 2 +-
arch/arm/kernel/smccc-call.S | 7 ++++---
arch/arm64/kernel/arm64ksyms.c | 2 +-
arch/arm64/kernel/asm-offsets.c | 7 +++++--
arch/arm64/kernel/smccc-call.S | 7 ++++---
include/linux/arm-smccc.h | 27 +++++++++++++++++++++++----
6 files changed, 38 insertions(+), 14 deletions(-)

diff --git a/arch/arm/kernel/armksyms.c b/arch/arm/kernel/armksyms.c
index 7e45f69..c2a8e79 100644
--- a/arch/arm/kernel/armksyms.c
+++ b/arch/arm/kernel/armksyms.c
@@ -178,6 +178,6 @@
#endif

#ifdef CONFIG_HAVE_ARM_SMCCC
-EXPORT_SYMBOL(arm_smccc_smc);
+EXPORT_SYMBOL(__arm_smccc_smc);
EXPORT_SYMBOL(arm_smccc_hvc);
#endif
diff --git a/arch/arm/kernel/smccc-call.S b/arch/arm/kernel/smccc-call.S
index 2e48b67..eb666d7 100644
--- a/arch/arm/kernel/smccc-call.S
+++ b/arch/arm/kernel/smccc-call.S
@@ -46,11 +46,12 @@ UNWIND( .fnend)
/*
* void smccc_smc(unsigned long a0, unsigned long a1, unsigned long a2,
* unsigned long a3, unsigned long a4, unsigned long a5,
- * unsigned long a6, unsigned long a7, struct arm_smccc_res *res)
+ * unsigned long a6, unsigned long a7, struct arm_smccc_res *res,
+ * struct arm_smccc_quirk *quirk)
*/
-ENTRY(arm_smccc_smc)
+ENTRY(__arm_smccc_smc)
SMCCC SMCCC_SMC
-ENDPROC(arm_smccc_smc)
+ENDPROC(__arm_smccc_smc)

/*
* void smccc_hvc(unsigned long a0, unsigned long a1, unsigned long a2,
diff --git a/arch/arm64/kernel/arm64ksyms.c b/arch/arm64/kernel/arm64ksyms.c
index 78f3680..43370a0 100644
--- a/arch/arm64/kernel/arm64ksyms.c
+++ b/arch/arm64/kernel/arm64ksyms.c
@@ -73,5 +73,5 @@
#endif

/* arm-smccc */
-EXPORT_SYMBOL(arm_smccc_smc);
+EXPORT_SYMBOL(__arm_smccc_smc);
EXPORT_SYMBOL(arm_smccc_hvc);
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index bc049af..b3bb7ef 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -143,8 +143,11 @@ int main(void)
DEFINE(SLEEP_STACK_DATA_SYSTEM_REGS, offsetof(struct sleep_stack_data, system_regs));
DEFINE(SLEEP_STACK_DATA_CALLEE_REGS, offsetof(struct sleep_stack_data, callee_saved_regs));
#endif
- DEFINE(ARM_SMCCC_RES_X0_OFFS, offsetof(struct arm_smccc_res, a0));
- DEFINE(ARM_SMCCC_RES_X2_OFFS, offsetof(struct arm_smccc_res, a2));
+ DEFINE(ARM_SMCCC_RES_X0_OFFS, offsetof(struct arm_smccc_res, a0));
+ DEFINE(ARM_SMCCC_RES_X2_OFFS, offsetof(struct arm_smccc_res, a2));
+ DEFINE(ARM_SMCCC_QUIRK_ID_OFFS, offsetof(struct arm_smccc_quirk, id));
+ DEFINE(ARM_SMCCC_QUIRK_STATE_OFFS, offsetof(struct arm_smccc_quirk, state));
+
BLANK();
DEFINE(HIBERN_PBE_ORIG, offsetof(struct pbe, orig_address));
DEFINE(HIBERN_PBE_ADDR, offsetof(struct pbe, address));
diff --git a/arch/arm64/kernel/smccc-call.S b/arch/arm64/kernel/smccc-call.S
index ae0496f..6290696 100644
--- a/arch/arm64/kernel/smccc-call.S
+++ b/arch/arm64/kernel/smccc-call.S
@@ -27,11 +27,12 @@
/*
* void arm_smccc_smc(unsigned long a0, unsigned long a1, unsigned long a2,
* unsigned long a3, unsigned long a4, unsigned long a5,
- * unsigned long a6, unsigned long a7, struct arm_smccc_res *res)
+ * unsigned long a6, unsigned long a7, struct arm_smccc_res *res,
+ * struct arm_smccc_quirk *quirk)
*/
-ENTRY(arm_smccc_smc)
+ENTRY(__arm_smccc_smc)
SMCCC smc
-ENDPROC(arm_smccc_smc)
+ENDPROC(__arm_smccc_smc)

/*
* void arm_smccc_hvc(unsigned long a0, unsigned long a1, unsigned long a2,
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index b5abfda..ab937db 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -72,19 +72,34 @@ struct arm_smccc_res {
};

/**
- * arm_smccc_smc() - make SMC calls
+ * struct arm_smccc_quirk - Contains quirk information
+ * @id: quirk identification
+ * @state: quirk specific information
+ * @a6: Qualcomm quirk entry for returning post-smc call contents of a6
+ */
+struct arm_smccc_quirk {
+ int id;
+ union {
+ unsigned long a6;
+ } state;
+};
+
+/**
+ * __arm_smccc_smc() - make SMC calls
* @a0-a7: arguments passed in registers 0 to 7
* @res: result values from registers 0 to 3
+ * @quirk: points to an arm_smccc_quirk, or NULL when no quirks are required.
*
* This function is used to make SMC calls following SMC Calling Convention.
* The content of the supplied param are copied to registers 0 to 7 prior
* to the SMC instruction. The return values are updated with the content
- * from register 0 to 3 on return from the SMC instruction.
+ * from register 0 to 3 on return from the SMC instruction. An optional
+ * quirk structure provides vendor specific behavior.
*/
-asmlinkage void arm_smccc_smc(unsigned long a0, unsigned long a1,
+asmlinkage void __arm_smccc_smc(unsigned long a0, unsigned long a1,
unsigned long a2, unsigned long a3, unsigned long a4,
unsigned long a5, unsigned long a6, unsigned long a7,
- struct arm_smccc_res *res);
+ struct arm_smccc_res *res, struct arm_smccc_quirk *quirk);

/**
* arm_smccc_hvc() - make HVC calls
@@ -101,4 +116,8 @@ asmlinkage void arm_smccc_hvc(unsigned long a0, unsigned long a1,
unsigned long a5, unsigned long a6, unsigned long a7,
struct arm_smccc_res *res);

+#define arm_smccc_smc(...) __arm_smccc_smc(__VA_ARGS__, NULL)
+
+#define arm_smccc_smc_quirk(...) __arm_smccc_smc(__VA_ARGS__)
+
#endif /*__LINUX_ARM_SMCCC_H*/
--
1.9.1