[linux-yocto] [PATCH 21/25] driver, misc: enhance service layer for u-boot w/o SMC support

[Meng.Li at windriver.com]

From: Richard Gong <richard.gong at intel.com>

commit  ecc5919628b706ecc57300c7dbea38e59f2bede1 from
https://github.com/altera-opensource/linux-socfpga.git

Service layer makes a SMC call to u-boot for the shared memory. If SMC is
not supported at u-boot, u-boot will return service layer a invalid value
and cause service layer probe failure. Kernel crashes as a result.

This patch is used to enhance service layer driver. So that if u-boot
doesn't support SMC yet, the service layer driver probe will fail without
crashing the kernel.

FPGA configuration will not work in the case which u-boot doesn't support
SMC.

Signed-off-by: Richard Gong <richard.gong at intel.com>
Signed-off-by: Meng Li <Meng.Li at windriver.com>
---
 drivers/misc/intel-service.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/misc/intel-service.c b/drivers/misc/intel-service.c
index 18690b8..c87d9aa 100644
--- a/drivers/misc/intel-service.c
+++ b/drivers/misc/intel-service.c
@@ -194,6 +194,9 @@ struct intel_svc_chan *request_svc_channel_byname(
 	int i;
 
 	chan = ERR_PTR(-EPROBE_DEFER);
+	if (list_empty(&svc_ctrl))
+		return ERR_PTR(-ENODEV);
+
 	controller = list_first_entry(&svc_ctrl,
 				      struct intel_svc_controller, node);
 	for (i = 0; i < SVC_NUM_CHANNEL; i++) {
-- 
1.7.9.5