[PATCH v5 05/14] ARM: mvebu: Split low level functions to manipulate HW coherency

Gregory CLEMENT
2014-03-25T22:48:16Z

Actually enabling coherency and adding a CPU on a SMP group are two
different operations which can be done separately. This patch splits
this in two functions.

Moreover as they use common pattern, this patch also creates local low
level functions (ll_get_coherency_base and ll_get_cpuid) to be used by
the exposed functions (ll_add_cpu_to_smp_group and
ll_enable_coherency)

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
---
arch/arm/mach-mvebu/coherency.c | 8 ++--
arch/arm/mach-mvebu/coherency_ll.S | 94 +++++++++++++++++++++++++-------------
arch/arm/mach-mvebu/headsmp.S | 6 ++-
3 files changed, 72 insertions(+), 36 deletions(-)

diff --git a/arch/arm/mach-mvebu/coherency.c b/arch/arm/mach-mvebu/coherency.c
index ad61251f7faf..6718193ebd3f 100644
--- a/arch/arm/mach-mvebu/coherency.c
+++ b/arch/arm/mach-mvebu/coherency.c
@@ -43,8 +43,9 @@ static struct of_device_id of_coherency_table[] = {
{ /* end of list */ },
};

-/* Function defined in coherency_ll.S */
-int ll_set_cpu_coherent(void);
+/* Functions defined in coherency_ll.S */
+int ll_enable_coherency(void);
+void ll_add_cpu_to_smp_group(void);

int set_cpu_coherent(void)
{
@@ -54,7 +55,8 @@ int set_cpu_coherent(void)
return 1;
}

- return ll_set_cpu_coherent();
+ ll_add_cpu_to_smp_group();
+ return ll_enable_coherency();
}

static inline void mvebu_hwcc_sync_io_barrier(void)
diff --git a/arch/arm/mach-mvebu/coherency_ll.S b/arch/arm/mach-mvebu/coherency_ll.S
index 6cb26b919787..c7179a03891d 100644
--- a/arch/arm/mach-mvebu/coherency_ll.S
+++ b/arch/arm/mach-mvebu/coherency_ll.S
@@ -24,52 +24,84 @@
#include <asm/cp15.h>

.text
-
-ENTRY(ll_set_cpu_coherent)
+/* Returns with the coherency address in r1 (r0 is untouched)*/
+ENTRY(ll_get_coherency_base)
mrc p15, 0, r1, c1, c0, 0
tst r1, #CR_M @ Check MMU bit enabled
bne 1f

- /* use physical address of the coherency register*/
- adr r0, 3f
- ldr r3, [r0]
- ldr r0, [r0, r3]
+ /* use physical address of the coherency register */
+ adr r1, 3f
+ ldr r3, [r1]
+ ldr r1, [r1, r3]
b 2f
1:
- /* use virtual address of the coherency register*/
- ldr r0, =coherency_base
- ldr r0, [r0]
+ /* use virtual address of the coherency register */
+ ldr r1, =coherency_base
+ ldr r1, [r1]
2:
- /* Create bit by cpu index */
- mrc 15, 0, r1, cr0, cr0, 5
- and r1, r1, #15
+ mov pc, lr
+ENDPROC(ll_get_coherency_base)
+
+/* Returns with the CPU ID in r3 (r0 is untouched)*/
+ENTRY(ll_get_cpuid)
+ mrc 15, 0, r3, cr0, cr0, 5
+ and r3, r3, #15
mov r2, #(1 << 24)
- lsl r1, r2, r1
- ARM_BE8(rev r1, r1)
+ lsl r3, r2, r3
+ ARM_BE8(rev r3, r3)
+ mov pc, lr
+ENDPROC(ll_get_cpuid)

- /* Add CPU to SMP group - Atomic */
- add r3, r0, #ARMADA_XP_CFB_CTL_REG_OFFSET
-1:
- ldrex r2, [r3]
- orr r2, r2, r1
- strex r0, r2, [r3]
- cmp r0, #0
- bne 1b
+/* ll_add_cpu_to_smp_group, ll_enable_coherency and
+ * ll_disable_coherency use strex/ldrex whereas MMU can be off. The
+ * Armada XP SoC has an exclusive monitor that can track transactions
+ * to Device and/or SO and as such also when MMU is disabled the
+ * exclusive transactions will be functional
+ */

- /* Enable coherency on CPU - Atomic */
- add r3, r3, #ARMADA_XP_CFB_CFG_REG_OFFSET
+ENTRY(ll_add_cpu_to_smp_group)
+ /*
+ * r0 being untouched in ll_get_coherency_base and
+ * ll_get_cpuid, we can use it to save lr modifing it with the
+ * following bl
+ */
+ mov r0, lr
+ bl ll_get_coherency_base
+ bl ll_get_cpuid
+ mov lr, r0
+ add r0, r1, #ARMADA_XP_CFB_CFG_REG_OFFSET
1:
- ldrex r2, [r3]
- orr r2, r2, r1
- strex r0, r2, [r3]
- cmp r0, #0
- bne 1b
+ ldrex r2, [r0]
+ orr r2, r2, r3
+ strex r1, r2, [r0]
+ cmp r1, #0
+ bne 1b
+ mov pc, lr
+ENDPROC(ll_add_cpu_to_smp_group)

+ENTRY(ll_enable_coherency)
+ /*
+ * r0 being untouched in ll_get_coherency_base and
+ * ll_get_cpuid, we can use it to save lr modifing it with the
+ * following bl
+ */
+ mov r0, lr
+ bl ll_get_coherency_base
+ bl ll_get_cpuid
+ mov lr, r0
+ add r0, r1, #ARMADA_XP_CFB_CTL_REG_OFFSET
+1:
+ ldrex r2, [r0]
+ orr r2, r2, r3
+ strex r1, r2, [r0]
+ cmp r1, #0
+ bne 1b
dsb
-
mov r0, #0
mov pc, lr
-ENDPROC(ll_set_cpu_coherent)
+ENDPROC(ll_enable_coherency)
+

.align 2
3:
diff --git a/arch/arm/mach-mvebu/headsmp.S b/arch/arm/mach-mvebu/headsmp.S
index cf7abe6554f7..2c4032e368ba 100644
--- a/arch/arm/mach-mvebu/headsmp.S
+++ b/arch/arm/mach-mvebu/headsmp.S
@@ -31,8 +31,10 @@
ENTRY(armada_xp_secondary_startup)
ARM_BE8(setend be ) @ go BE8 if entered LE

- /* Add CPU to coherency fabric */
- bl ll_set_cpu_coherent
+ bl ll_add_cpu_to_smp_group
+
+ bl ll_enable_coherency
+
b secondary_startup

ENDPROC(armada_xp_secondary_startup)
--
1.8.1.2