ssi-fiq.S

  1/* SPDX-License-Identifier: GPL-2.0-only */
  2/*
  3 *  Copyright (C) 2009 Sascha Hauer <s.hauer@pengutronix.de>
  4 */
  5
  6#include <linux/linkage.h>
  7#include <asm/assembler.h>
  8
  9/*
 10 * r8  = bit 0-15: tx offset, bit 16-31: tx buffer size
 11 * r9  = bit 0-15: rx offset, bit 16-31: rx buffer size
 12 */
 13
 14#define SSI_STX0	0x00
 15#define SSI_SRX0	0x08
 16#define SSI_SISR	0x14
 17#define SSI_SIER	0x18
 18#define SSI_SACNT	0x38
 19
 20#define SSI_SACNT_AC97EN	(1 << 0)
 21
 22#define SSI_SIER_TFE0_EN	(1 << 0)
 23#define SSI_SISR_TFE0		(1 << 0)
 24#define SSI_SISR_RFF0		(1 << 2)
 25#define SSI_SIER_RFF0_EN	(1 << 2)
 26
 27		.text
 28		.global	imx_ssi_fiq_start
 29		.global	imx_ssi_fiq_end
 30		.global imx_ssi_fiq_base
 31		.global imx_ssi_fiq_rx_buffer
 32		.global imx_ssi_fiq_tx_buffer
 33
 34/*
 35 * imx_ssi_fiq_start is _intentionally_ not marked as a function symbol
 36 * using ENDPROC().  imx_ssi_fiq_start and imx_ssi_fiq_end are used to
 37 * mark the function body so that it can be copied to the FIQ vector in
 38 * the vectors page.  imx_ssi_fiq_start should only be called as the result
 39 * of an FIQ: calling it directly will not work.
 40 */
 41imx_ssi_fiq_start:
 42		ldr r12, .L_imx_ssi_fiq_base
 43
 44		/* TX */
 45		ldr r13, .L_imx_ssi_fiq_tx_buffer
 46
 47		/* shall we send? */
 48		ldr r11, [r12, #SSI_SIER]
 49		tst r11, #SSI_SIER_TFE0_EN
 50		beq 1f
 51
 52		/* TX FIFO empty? */
 53		ldr r11, [r12, #SSI_SISR]
 54		tst r11, #SSI_SISR_TFE0
 55		beq 1f
 56
 57		mov r10, #0x10000
 58		sub r10, #1
 59		and r10, r10, r8	/* r10: current buffer offset */
 60
 61		add r13, r13, r10
 62
 63		ldrh r11, [r13]
 64		strh r11, [r12, #SSI_STX0]
 65
 66		ldrh r11, [r13, #2]
 67		strh r11, [r12, #SSI_STX0]
 68
 69		ldrh r11, [r13, #4]
 70		strh r11, [r12, #SSI_STX0]
 71
 72		ldrh r11, [r13, #6]
 73		strh r11, [r12, #SSI_STX0]
 74
 75		add r10, #8
 76		lsr r11, r8, #16	/* r11: buffer size */
 77		cmp r10, r11
 78		lslgt r8, r11, #16
 79		addle r8, #8
 801:
 81		/* RX */
 82
 83		/* shall we receive? */
 84		ldr r11, [r12, #SSI_SIER]
 85		tst r11, #SSI_SIER_RFF0_EN
 86		beq 1f
 87
 88		/* RX FIFO full? */
 89		ldr r11, [r12, #SSI_SISR]
 90		tst r11, #SSI_SISR_RFF0
 91		beq 1f
 92
 93		ldr r13, .L_imx_ssi_fiq_rx_buffer
 94
 95		mov r10, #0x10000
 96		sub r10, #1
 97		and r10, r10, r9	/* r10: current buffer offset */
 98
 99		add r13, r13, r10
100
101		ldr r11, [r12, #SSI_SACNT]
102		tst r11, #SSI_SACNT_AC97EN
103
104		ldr r11, [r12, #SSI_SRX0]
105		strh r11, [r13]
106
107		ldr r11, [r12, #SSI_SRX0]
108		strh r11, [r13, #2]
109
110		/* dummy read to skip slot 12 */
111		ldrne r11, [r12, #SSI_SRX0]
112
113		ldr r11, [r12, #SSI_SRX0]
114		strh r11, [r13, #4]
115
116		ldr r11, [r12, #SSI_SRX0]
117		strh r11, [r13, #6]
118
119		/* dummy read to skip slot 12 */
120		ldrne r11, [r12, #SSI_SRX0]
121
122		add r10, #8
123		lsr r11, r9, #16	/* r11: buffer size */
124		cmp r10, r11
125		lslgt r9, r11, #16
126		addle r9, #8
127
1281:
129		@ return from FIQ
130		subs	pc, lr, #4
131
132		.align
133.L_imx_ssi_fiq_base:
134imx_ssi_fiq_base:
135		.word 0x0
136.L_imx_ssi_fiq_rx_buffer:
137imx_ssi_fiq_rx_buffer:
138		.word 0x0
139.L_imx_ssi_fiq_tx_buffer:
140imx_ssi_fiq_tx_buffer:
141		.word 0x0
142.L_imx_ssi_fiq_end:
143imx_ssi_fiq_end:
144