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authorDave Martin <dave.martin@linaro.org>2012-08-10 12:53:24 +0100
committerSascha Hauer <s.hauer@pengutronix.de>2012-08-13 21:33:14 +0200
commit7095b95654302ceb8a011ee883d1500851061b0d (patch)
treed93d153741e33763191e1c3837cb981708e07456 /arch/arm/plat-mxc
parenta745f039b901b43937f61f149ad9cee2796ed299 (diff)
ARM: mxc: ssi-fiq: Make ssi-fiq.S Thumb-2 compatible
Because FIQ handlers get copied straight into the vectors page to the FIQ vector entry point, FIQ handlers in a Thumb-2 kernel must start in Thumb-2. A Thumb-2 kernel enters all exception vectors in Thumb-2. This patch adapts the mxc SSI FIQ code suitable for a Thumb-2 kernel. The code contained use of r13 (sp) which isn't allowed in Thumb-2. r11 and r13 have been swapped throughout the file to work around this. Currently, the way that the function to be copied is located using labels is a bit ugly: we cannot annotate the FIQ handler properly as a Thumb-2 function, because this would set bit 0 of the label address seen by the linker, causing off-by-one errors when copying the function. Ideally, the copy would be done with fncpy(), but this would require changes to the common set_fiq_handler() function. For now, we don't touch this. References to locally-defined global symbols with adr and ldr may not be accepted by the assembler in Thumb-2. Local shadow symbols are added to work around this. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Diffstat (limited to 'arch/arm/plat-mxc')
-rw-r--r--arch/arm/plat-mxc/ssi-fiq.S89
1 files changed, 50 insertions, 39 deletions
diff --git a/arch/arm/plat-mxc/ssi-fiq.S b/arch/arm/plat-mxc/ssi-fiq.S
index 8397a2dd19f..a8b93c5f29b 100644
--- a/arch/arm/plat-mxc/ssi-fiq.S
+++ b/arch/arm/plat-mxc/ssi-fiq.S
@@ -34,91 +34,98 @@
.global imx_ssi_fiq_rx_buffer
.global imx_ssi_fiq_tx_buffer
+/*
+ * imx_ssi_fiq_start is _intentionally_ not marked as a function symbol
+ * using ENDPROC(). imx_ssi_fiq_start and imx_ssi_fiq_end are used to
+ * mark the function body so that it can be copied to the FIQ vector in
+ * the vectors page. imx_ssi_fiq_start should only be called as the result
+ * of an FIQ: calling it directly will not work.
+ */
imx_ssi_fiq_start:
- ldr r12, imx_ssi_fiq_base
+ ldr r12, .L_imx_ssi_fiq_base
/* TX */
- ldr r11, imx_ssi_fiq_tx_buffer
+ ldr r13, .L_imx_ssi_fiq_tx_buffer
/* shall we send? */
- ldr r13, [r12, #SSI_SIER]
- tst r13, #SSI_SIER_TFE0_EN
+ ldr r11, [r12, #SSI_SIER]
+ tst r11, #SSI_SIER_TFE0_EN
beq 1f
/* TX FIFO empty? */
- ldr r13, [r12, #SSI_SISR]
- tst r13, #SSI_SISR_TFE0
+ ldr r11, [r12, #SSI_SISR]
+ tst r11, #SSI_SISR_TFE0
beq 1f
mov r10, #0x10000
sub r10, #1
and r10, r10, r8 /* r10: current buffer offset */
- add r11, r11, r10
+ add r13, r13, r10
- ldrh r13, [r11]
- strh r13, [r12, #SSI_STX0]
+ ldrh r11, [r13]
+ strh r11, [r12, #SSI_STX0]
- ldrh r13, [r11, #2]
- strh r13, [r12, #SSI_STX0]
+ ldrh r11, [r13, #2]
+ strh r11, [r12, #SSI_STX0]
- ldrh r13, [r11, #4]
- strh r13, [r12, #SSI_STX0]
+ ldrh r11, [r13, #4]
+ strh r11, [r12, #SSI_STX0]
- ldrh r13, [r11, #6]
- strh r13, [r12, #SSI_STX0]
+ ldrh r11, [r13, #6]
+ strh r11, [r12, #SSI_STX0]
add r10, #8
- lsr r13, r8, #16 /* r13: buffer size */
- cmp r10, r13
- lslgt r8, r13, #16
+ lsr r11, r8, #16 /* r11: buffer size */
+ cmp r10, r11
+ lslgt r8, r11, #16
addle r8, #8
1:
/* RX */
/* shall we receive? */
- ldr r13, [r12, #SSI_SIER]
- tst r13, #SSI_SIER_RFF0_EN
+ ldr r11, [r12, #SSI_SIER]
+ tst r11, #SSI_SIER_RFF0_EN
beq 1f
/* RX FIFO full? */
- ldr r13, [r12, #SSI_SISR]
- tst r13, #SSI_SISR_RFF0
+ ldr r11, [r12, #SSI_SISR]
+ tst r11, #SSI_SISR_RFF0
beq 1f
- ldr r11, imx_ssi_fiq_rx_buffer
+ ldr r13, .L_imx_ssi_fiq_rx_buffer
mov r10, #0x10000
sub r10, #1
and r10, r10, r9 /* r10: current buffer offset */
- add r11, r11, r10
+ add r13, r13, r10
- ldr r13, [r12, #SSI_SACNT]
- tst r13, #SSI_SACNT_AC97EN
+ ldr r11, [r12, #SSI_SACNT]
+ tst r11, #SSI_SACNT_AC97EN
- ldr r13, [r12, #SSI_SRX0]
- strh r13, [r11]
+ ldr r11, [r12, #SSI_SRX0]
+ strh r11, [r13]
- ldr r13, [r12, #SSI_SRX0]
- strh r13, [r11, #2]
+ ldr r11, [r12, #SSI_SRX0]
+ strh r11, [r13, #2]
/* dummy read to skip slot 12 */
- ldrne r13, [r12, #SSI_SRX0]
+ ldrne r11, [r12, #SSI_SRX0]
- ldr r13, [r12, #SSI_SRX0]
- strh r13, [r11, #4]
+ ldr r11, [r12, #SSI_SRX0]
+ strh r11, [r13, #4]
- ldr r13, [r12, #SSI_SRX0]
- strh r13, [r11, #6]
+ ldr r11, [r12, #SSI_SRX0]
+ strh r11, [r13, #6]
/* dummy read to skip slot 12 */
- ldrne r13, [r12, #SSI_SRX0]
+ ldrne r11, [r12, #SSI_SRX0]
add r10, #8
- lsr r13, r9, #16 /* r13: buffer size */
- cmp r10, r13
- lslgt r9, r13, #16
+ lsr r11, r9, #16 /* r11: buffer size */
+ cmp r10, r11
+ lslgt r9, r11, #16
addle r9, #8
1:
@@ -126,11 +133,15 @@ imx_ssi_fiq_start:
subs pc, lr, #4
.align
+.L_imx_ssi_fiq_base:
imx_ssi_fiq_base:
.word 0x0
+.L_imx_ssi_fiq_rx_buffer:
imx_ssi_fiq_rx_buffer:
.word 0x0
+.L_imx_ssi_fiq_tx_buffer:
imx_ssi_fiq_tx_buffer:
.word 0x0
+.L_imx_ssi_fiq_end:
imx_ssi_fiq_end: