1 files changed, 144 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 000000000..68d7fdea9
--- /dev/null
+++ b/arch/arm/mach-imx/ssi-fiq.S
@@ -0,0 +1,144 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ *  Copyright (C) 2009 Sascha Hauer <s.hauer@pengutronix.de>
+ */
+
+#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:
+