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
145