[v2,2/2] firmware: qcom: scm: Fix interrupted SCM calls

Message ID 1483054046-3327-3-git-send-email-andy.gross@linaro.org
State Superseded
Headers show

Commit Message

Andy Gross Dec. 29, 2016, 11:27 p.m.
This patch adds a Qualcomm specific quirk to the arm_smccc_smc call.

On Qualcomm ARM64 platforms, the SMC call can return before it has
completed.  If this occurs, the call can be restarted, but it requires
using the returned session ID value from the interrupted SMC call.

The quirk stores off the session ID from the interrupted call in the
quirk structure so that it can be used by the caller.

This patch folds in a fix given by Sricharan R:
https://lkml.org/lkml/2016/9/28/272

Signed-off-by: Andy Gross <andy.gross@linaro.org>

---
 arch/arm64/kernel/smccc-call.S |  9 ++++++++-
 drivers/firmware/qcom_scm-64.c | 13 ++++++++++---
 include/linux/arm-smccc.h      | 11 ++++++++---
 3 files changed, 26 insertions(+), 7 deletions(-)

-- 
1.9.1

Comments

Will Deacon Jan. 4, 2017, 5:33 p.m. | #1
On Thu, Dec 29, 2016 at 05:27:26PM -0600, Andy Gross wrote:
> This patch adds a Qualcomm specific quirk to the arm_smccc_smc call.

> 

> On Qualcomm ARM64 platforms, the SMC call can return before it has

> completed.  If this occurs, the call can be restarted, but it requires

> using the returned session ID value from the interrupted SMC call.

> 

> The quirk stores off the session ID from the interrupted call in the

> quirk structure so that it can be used by the caller.

> 

> This patch folds in a fix given by Sricharan R:

> https://lkml.org/lkml/2016/9/28/272

> 

> Signed-off-by: Andy Gross <andy.gross@linaro.org>

> ---

>  arch/arm64/kernel/smccc-call.S |  9 ++++++++-

>  drivers/firmware/qcom_scm-64.c | 13 ++++++++++---

>  include/linux/arm-smccc.h      | 11 ++++++++---

>  3 files changed, 26 insertions(+), 7 deletions(-)


Reviewed-by: Will Deacon <will.deacon@arm.com>


Thanks for sticking with this, it looks good to me now.

Will

Patch

diff --git a/arch/arm64/kernel/smccc-call.S b/arch/arm64/kernel/smccc-call.S
index 6290696..72ecdca 100644
--- a/arch/arm64/kernel/smccc-call.S
+++ b/arch/arm64/kernel/smccc-call.S
@@ -12,6 +12,7 @@ 
  *
  */
 #include <linux/linkage.h>
+#include <linux/arm-smccc.h>
 #include <asm/asm-offsets.h>
 
 	.macro SMCCC instr
@@ -20,7 +21,13 @@ 
 	ldr	x4, [sp]
 	stp	x0, x1, [x4, #ARM_SMCCC_RES_X0_OFFS]
 	stp	x2, x3, [x4, #ARM_SMCCC_RES_X2_OFFS]
-	ret
+	ldr	x4, [sp, #8]
+	cbz	x4, 1f /* no quirk structure */
+	ldr	x9, [x4, #ARM_SMCCC_QUIRK_ID_OFFS]
+	cmp	x9, #ARM_SMCCC_QUIRK_QCOM_A6
+	b.ne	1f
+	str	x6, [x4, ARM_SMCCC_QUIRK_STATE_OFFS]
+1:	ret
 	.cfi_endproc
 	.endm
 
diff --git a/drivers/firmware/qcom_scm-64.c b/drivers/firmware/qcom_scm-64.c
index 4a0f5ea..1e2e519 100644
--- a/drivers/firmware/qcom_scm-64.c
+++ b/drivers/firmware/qcom_scm-64.c
@@ -91,6 +91,7 @@  static int qcom_scm_call(struct device *dev, u32 svc_id, u32 cmd_id,
 	dma_addr_t args_phys = 0;
 	void *args_virt = NULL;
 	size_t alloc_len;
+	struct arm_smccc_quirk quirk = {.id = ARM_SMCCC_QUIRK_QCOM_A6};
 
 	if (unlikely(arglen > N_REGISTER_ARGS)) {
 		alloc_len = N_EXT_QCOM_SCM_ARGS * sizeof(u64);
@@ -131,10 +132,16 @@  static int qcom_scm_call(struct device *dev, u32 svc_id, u32 cmd_id,
 					 qcom_smccc_convention,
 					 ARM_SMCCC_OWNER_SIP, fn_id);
 
+		quirk.state.a6 = 0;
+
 		do {
-			arm_smccc_smc(cmd, desc->arginfo, desc->args[0],
-				      desc->args[1], desc->args[2], x5, 0, 0,
-				      res);
+			arm_smccc_smc_quirk(cmd, desc->arginfo, desc->args[0],
+				      desc->args[1], desc->args[2], x5,
+				      quirk.state.a6, 0, res, &quirk);
+
+			if (res->a0 == QCOM_SCM_INTERRUPTED)
+				cmd = res->a0;
+
 		} while (res->a0 == QCOM_SCM_INTERRUPTED);
 
 		mutex_unlock(&qcom_scm_lock);
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index cde4f1f..64d0454 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -14,9 +14,6 @@ 
 #ifndef __LINUX_ARM_SMCCC_H
 #define __LINUX_ARM_SMCCC_H
 
-#include <linux/linkage.h>
-#include <linux/types.h>
-
 /*
  * This file provides common defines for ARM SMC Calling Convention as
  * specified in
@@ -60,6 +57,13 @@ 
 #define ARM_SMCCC_OWNER_TRUSTED_OS	50
 #define ARM_SMCCC_OWNER_TRUSTED_OS_END	63
 
+#define ARM_SMCCC_QUIRK_NONE		0
+#define ARM_SMCCC_QUIRK_QCOM_A6		1 /* Save/restore register a6 */
+
+#ifndef __ASSEMBLY__
+
+#include <linux/linkage.h>
+#include <linux/types.h>
 /**
  * struct arm_smccc_res - Result from SMC/HVC call
  * @a0-a3 result values from registers 0 to 3
@@ -121,4 +125,5 @@  asmlinkage void arm_smccc_hvc(unsigned long a0, unsigned long a1,
 #define arm_smccc_smc_quirk(a0, a1, a2, a3, a4, a5, a6, a7, res, quirk) \
 	__arm_smccc_smc(a0, a1, a2, a3, a4, a5, a6, a7, res, quirk)
 
+#endif /*__ASSEMBLY__*/
 #endif /*__LINUX_ARM_SMCCC_H*/