ARMv8: Allow SiP service extensions on top of PSCI code

Allow PSCI layer to handle any SiP service functions added by
platform vendors. PSCI layer will look for SiP service function
in the SiP function table located in '._secure_svc_tbl_entries'
section if the SMC function identifier is not found in the PSCI
standard functions table. Use DECLARE_SECURE_SVC macro to declare
and add platform specific SiP service function.
This new section '._secure_svc_tbl_entries' is located next to
'._secure.text' section. Refer to arch/arm/cpu/armv8/u-boot.lds.

Signed-off-by: Chee Hong Ang <chee.hong.ang@intel.com>

3 files changed, 62 insertions, 6 deletions

diff --git a/arch/arm/cpu/armv8/psci.S b/arch/arm/cpu/armv8/psci.S
index 358df8fee9..fc42d807b5 100644
--- a/arch/arm/cpu/armv8/psci.S
+++ b/arch/arm/cpu/armv8/psci.S
@@ -8,6 +8,7 @@
 #include <config.h>
 #include <linux/linkage.h>
 #include <asm/psci.h>
+#include <asm/secure.h>
 
 /* Default PSCI function, return -1, Not Implemented */
 #define PSCI_DEFAULT(__fn) \
@@ -147,18 +148,38 @@ handle_psci:
 3:	mov	x0, #ARM_PSCI_RET_NI
 	psci_return
 
-unknown_smc_id:
-	ldr	x0, =0xFFFFFFFF
+/*
+ * Handle SiP service functions defined in SiP service function table.
+ * Use DECLARE_SECURE_SVC(_name, _id, _fn) to add platform specific SiP
+ * service function into the SiP service function table.
+ * SiP service function table is located in '._secure_svc_tbl_entries' section,
+ * which is next to '._secure.text' section.
+ */
+handle_svc:
+	adr	x9, __secure_svc_tbl_start
+	adr	x10, __secure_svc_tbl_end
+	subs	x12, x10, x9	/* Get number of entries in table */
+	b.eq	2f		/* Make sure SiP function table is not empty */
+	psci_enter
+1:	ldr x10, [x9]		/* Load SiP function table */
+	ldr x11, [x9, #8]
+	cmp	w10, w0
+	b.eq	2b		/* SiP service function found */
+	add x9, x9, #SECURE_SVC_TBL_OFFSET	/* Move to next entry */
+	subs	x12, x12, #SECURE_SVC_TBL_OFFSET
+	b.eq	3b		/* If reach the end, bail out */
+	b	1b
+2:	ldr	x0, =0xFFFFFFFF
 	eret
 
 handle_smc32:
 	/* SMC function ID  0x84000000-0x8400001F: 32 bits PSCI */
 	ldr	w9, =0x8400001F
 	cmp	w0, w9
-	b.gt	unknown_smc_id
+	b.gt	handle_svc
 	ldr	w9, =0x84000000
 	cmp	w0, w9
-	b.lt	unknown_smc_id
+	b.lt	handle_svc
 
 	adr	x9, _psci_32_table
 	b	handle_psci
@@ -171,10 +192,10 @@ handle_smc64:
 	/* SMC function ID 0xC4000000-0xC400001F: 64 bits PSCI */
 	ldr	x9, =0xC400001F
 	cmp	x0, x9
-	b.gt	unknown_smc_id
+	b.gt	handle_svc
 	ldr	x9, =0xC4000000
 	cmp	x0, x9
-	b.lt	unknown_smc_id
+	b.lt	handle_svc
 
 	adr	x9, _psci_64_table
 	b	handle_psci
diff --git a/arch/arm/cpu/armv8/u-boot.lds b/arch/arm/cpu/armv8/u-boot.lds
index 53de80f745..2554980595 100644
--- a/arch/arm/cpu/armv8/u-boot.lds
+++ b/arch/arm/cpu/armv8/u-boot.lds
@@ -58,6 +58,10 @@ SECTIONS
 		AT(ADDR(.__secure_start) + SIZEOF(.__secure_start))
 	{
 		*(._secure.text)
+		. = ALIGN(8);
+		__secure_svc_tbl_start = .;
+		KEEP(*(._secure_svc_tbl_entries))
+		__secure_svc_tbl_end = .;
 	}
 
 	.secure_data : AT(LOADADDR(.secure_text) + SIZEOF(.secure_text))
diff --git a/arch/arm/include/asm/secure.h b/arch/arm/include/asm/secure.h
index d23044a1c3..50582c972b 100644
--- a/arch/arm/include/asm/secure.h
+++ b/arch/arm/include/asm/secure.h
@@ -6,6 +6,37 @@
 #define __secure __attribute__ ((section ("._secure.text")))
 #define __secure_data __attribute__ ((section ("._secure.data")))
 
+#ifndef __ASSEMBLY__
+
+typedef struct secure_svc_tbl {
+	u32	id;
+#ifdef CONFIG_ARMV8_PSCI
+	u8	pad[4];
+#endif
+	void	*func;
+} secure_svc_tbl_t;
+
+/*
+ * Macro to declare a SiP function service in '_secure_svc_tbl_entries' section
+ */
+#define DECLARE_SECURE_SVC(_name, _id, _fn) \
+	static const secure_svc_tbl_t __secure_svc_ ## _name \
+		__attribute__((used, section("._secure_svc_tbl_entries"))) \
+			 = { \
+				.id = _id, \
+				.func = _fn }
+
+#else
+
+#ifdef CONFIG_ARMV8_PSCI
+#define SECURE_SVC_TBL_OFFSET		16
+#else
+#define SECURE_SVC_TBL_OFFSET		8
+
+#endif
+
+#endif /* __ASSEMBLY__ */
+
 #if defined(CONFIG_ARMV7_SECURE_BASE) || defined(CONFIG_ARMV8_SECURE_BASE)
 /*
  * Warning, horror ahead.