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-rw-r--r--arch/arm/mach-imx/ssi-fiq.S147
1 files changed, 147 insertions, 0 deletions
diff --git a/arch/arm/mach-imx/ssi-fiq.S b/arch/arm/mach-imx/ssi-fiq.S
new file mode 100644
index 0000000..a8b93c5
--- /dev/null
+++ b/arch/arm/mach-imx/ssi-fiq.S
@@ -0,0 +1,147 @@
+/*
+ * Copyright (C) 2009 Sascha Hauer <s.hauer@pengutronix.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+
+/*
+ * r8 = bit 0-15: tx offset, bit 16-31: tx buffer size
+ * r9 = bit 0-15: rx offset, bit 16-31: rx buffer size
+ */
+
+#define SSI_STX0 0x00
+#define SSI_SRX0 0x08
+#define SSI_SISR 0x14
+#define SSI_SIER 0x18
+#define SSI_SACNT 0x38
+
+#define SSI_SACNT_AC97EN (1 << 0)
+
+#define SSI_SIER_TFE0_EN (1 << 0)
+#define SSI_SISR_TFE0 (1 << 0)
+#define SSI_SISR_RFF0 (1 << 2)
+#define SSI_SIER_RFF0_EN (1 << 2)
+
+ .text
+ .global imx_ssi_fiq_start
+ .global imx_ssi_fiq_end
+ .global imx_ssi_fiq_base
+ .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, .L_imx_ssi_fiq_base
+
+ /* TX */
+ ldr r13, .L_imx_ssi_fiq_tx_buffer
+
+ /* shall we send? */
+ ldr r11, [r12, #SSI_SIER]
+ tst r11, #SSI_SIER_TFE0_EN
+ beq 1f
+
+ /* TX FIFO empty? */
+ 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 r13, r13, r10
+
+ ldrh r11, [r13]
+ strh r11, [r12, #SSI_STX0]
+
+ ldrh r11, [r13, #2]
+ strh r11, [r12, #SSI_STX0]
+
+ ldrh r11, [r13, #4]
+ strh r11, [r12, #SSI_STX0]
+
+ ldrh r11, [r13, #6]
+ strh r11, [r12, #SSI_STX0]
+
+ add r10, #8
+ lsr r11, r8, #16 /* r11: buffer size */
+ cmp r10, r11
+ lslgt r8, r11, #16
+ addle r8, #8
+1:
+ /* RX */
+
+ /* shall we receive? */
+ ldr r11, [r12, #SSI_SIER]
+ tst r11, #SSI_SIER_RFF0_EN
+ beq 1f
+
+ /* RX FIFO full? */
+ ldr r11, [r12, #SSI_SISR]
+ tst r11, #SSI_SISR_RFF0
+ beq 1f
+
+ ldr r13, .L_imx_ssi_fiq_rx_buffer
+
+ mov r10, #0x10000
+ sub r10, #1
+ and r10, r10, r9 /* r10: current buffer offset */
+
+ add r13, r13, r10
+
+ ldr r11, [r12, #SSI_SACNT]
+ tst r11, #SSI_SACNT_AC97EN
+
+ ldr r11, [r12, #SSI_SRX0]
+ strh r11, [r13]
+
+ ldr r11, [r12, #SSI_SRX0]
+ strh r11, [r13, #2]
+
+ /* dummy read to skip slot 12 */
+ ldrne r11, [r12, #SSI_SRX0]
+
+ ldr r11, [r12, #SSI_SRX0]
+ strh r11, [r13, #4]
+
+ ldr r11, [r12, #SSI_SRX0]
+ strh r11, [r13, #6]
+
+ /* dummy read to skip slot 12 */
+ ldrne r11, [r12, #SSI_SRX0]
+
+ add r10, #8
+ lsr r11, r9, #16 /* r11: buffer size */
+ cmp r10, r11
+ lslgt r9, r11, #16
+ addle r9, #8
+
+1:
+ @ return from FIQ
+ 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:
+