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authorSantosh Shilimkar <santosh.shilimkar@ti.com>2013-09-27 21:56:31 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2013-10-03 10:39:44 +0100
commitbc41b8724f24b9a27d1dcc6c974b8f686b38d554 (patch)
tree3572fd34c6dd22e6b72c0a855ac8943921d419ad /arch/arm
parent856337283a215b9f92189f22862e4415f4d6bd85 (diff)
ARM: 7846/1: Update SMP_ON_UP code to detect A9MPCore with 1 CPU devices
The generic code is well equipped to differentiate between SMP and UP configurations.However, there are some devices which use Cortex-A9 MP core IP with 1 CPU as configuration. To let these SOCs to co-exist in a CONFIG_SMP=y build by leveraging the SMP_ON_UP support, we need to additionally check the number the cores in Cortex-A9 MPCore configuration. Without such a check in place, the startup code tries to execute ALT_SMP() set of instructions which lead to CPU faults. The issue was spotted on TI's Aegis device and this patch makes now the device work with omap2plus_defconfig which enables SMP by default. The change is kept limited to only Cortex-A9 MPCore detection code. Note that if any future SoC *does* use 0x0 as the PERIPH_BASE, then the SCU address check code needs to be #ifdef'd for for the Aegis platform. Acked-by: Sricharan R <r.sricharan@ti.com> Signed-off-by: Vaibhav Bedia <vaibhav.bedia@ti.com> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm')
-rw-r--r--arch/arm/kernel/head.S21
1 files changed, 20 insertions, 1 deletions
diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index 2c7cc1e03473..476de57dcef2 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -487,7 +487,26 @@ __fixup_smp:
mrc p15, 0, r0, c0, c0, 5 @ read MPIDR
and r0, r0, #0xc0000000 @ multiprocessing extensions and
teq r0, #0x80000000 @ not part of a uniprocessor system?
- moveq pc, lr @ yes, assume SMP
+ bne __fixup_smp_on_up @ no, assume UP
+
+ @ Core indicates it is SMP. Check for Aegis SOC where a single
+ @ Cortex-A9 CPU is present but SMP operations fault.
+ mov r4, #0x41000000
+ orr r4, r4, #0x0000c000
+ orr r4, r4, #0x00000090
+ teq r3, r4 @ Check for ARM Cortex-A9
+ movne pc, lr @ Not ARM Cortex-A9,
+
+ @ If a future SoC *does* use 0x0 as the PERIPH_BASE, then the
+ @ below address check will need to be #ifdef'd or equivalent
+ @ for the Aegis platform.
+ mrc p15, 4, r0, c15, c0 @ get SCU base address
+ teq r0, #0x0 @ '0' on actual UP A9 hardware
+ beq __fixup_smp_on_up @ So its an A9 UP
+ ldr r0, [r0, #4] @ read SCU Config
+ and r0, r0, #0x3 @ number of CPUs
+ teq r0, #0x0 @ is 1?
+ movne pc, lr
__fixup_smp_on_up:
adr r0, 1f