1/*
2 *  Copyright (C) 2009 Sascha Hauer <s.hauer@pengutronix.de>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 */
8
9#include <linux/linkage.h>
10#include <asm/assembler.h>
11
12/*
13 * r8  = bit 0-15: tx offset, bit 16-31: tx buffer size
14 * r9  = bit 0-15: rx offset, bit 16-31: rx buffer size
15 */
16
17#define SSI_STX0	0x00
18#define SSI_SRX0	0x08
19#define SSI_SISR	0x14
20#define SSI_SIER	0x18
21#define SSI_SACNT	0x38
22
23#define SSI_SACNT_AC97EN	(1 << 0)
24
25#define SSI_SIER_TFE0_EN	(1 << 0)
26#define SSI_SISR_TFE0		(1 << 0)
27#define SSI_SISR_RFF0		(1 << 2)
28#define SSI_SIER_RFF0_EN	(1 << 2)
29
30		.text
31		.global	imx_ssi_fiq_start
32		.global	imx_ssi_fiq_end
33		.global imx_ssi_fiq_base
34		.global imx_ssi_fiq_rx_buffer
35		.global imx_ssi_fiq_tx_buffer
36
37/*
38 * imx_ssi_fiq_start is _intentionally_ not marked as a function symbol
39 * using ENDPROC().  imx_ssi_fiq_start and imx_ssi_fiq_end are used to
40 * mark the function body so that it can be copied to the FIQ vector in
41 * the vectors page.  imx_ssi_fiq_start should only be called as the result
42 * of an FIQ: calling it directly will not work.
43 */
44imx_ssi_fiq_start:
45		ldr r12, .L_imx_ssi_fiq_base
46
47		/* TX */
48		ldr r13, .L_imx_ssi_fiq_tx_buffer
49
50		/* shall we send? */
51		ldr r11, [r12, #SSI_SIER]
52		tst r11, #SSI_SIER_TFE0_EN
53		beq 1f
54
55		/* TX FIFO empty? */
56		ldr r11, [r12, #SSI_SISR]
57		tst r11, #SSI_SISR_TFE0
58		beq 1f
59
60		mov r10, #0x10000
61		sub r10, #1
62		and r10, r10, r8	/* r10: current buffer offset */
63
64		add r13, r13, r10
65
66		ldrh r11, [r13]
67		strh r11, [r12, #SSI_STX0]
68
69		ldrh r11, [r13, #2]
70		strh r11, [r12, #SSI_STX0]
71
72		ldrh r11, [r13, #4]
73		strh r11, [r12, #SSI_STX0]
74
75		ldrh r11, [r13, #6]
76		strh r11, [r12, #SSI_STX0]
77
78		add r10, #8
79		lsr r11, r8, #16	/* r11: buffer size */
80		cmp r10, r11
81		lslgt r8, r11, #16
82		addle r8, #8
831:
84		/* RX */
85
86		/* shall we receive? */
87		ldr r11, [r12, #SSI_SIER]
88		tst r11, #SSI_SIER_RFF0_EN
89		beq 1f
90
91		/* RX FIFO full? */
92		ldr r11, [r12, #SSI_SISR]
93		tst r11, #SSI_SISR_RFF0
94		beq 1f
95
96		ldr r13, .L_imx_ssi_fiq_rx_buffer
97
98		mov r10, #0x10000
99		sub r10, #1
100		and r10, r10, r9	/* r10: current buffer offset */
101
102		add r13, r13, r10
103
104		ldr r11, [r12, #SSI_SACNT]
105		tst r11, #SSI_SACNT_AC97EN
106
107		ldr r11, [r12, #SSI_SRX0]
108		strh r11, [r13]
109
110		ldr r11, [r12, #SSI_SRX0]
111		strh r11, [r13, #2]
112
113		/* dummy read to skip slot 12 */
114		ldrne r11, [r12, #SSI_SRX0]
115
116		ldr r11, [r12, #SSI_SRX0]
117		strh r11, [r13, #4]
118
119		ldr r11, [r12, #SSI_SRX0]
120		strh r11, [r13, #6]
121
122		/* dummy read to skip slot 12 */
123		ldrne r11, [r12, #SSI_SRX0]
124
125		add r10, #8
126		lsr r11, r9, #16	/* r11: buffer size */
127		cmp r10, r11
128		lslgt r9, r11, #16
129		addle r9, #8
130
1311:
132		@ return from FIQ
133		subs	pc, lr, #4
134
135		.align
136.L_imx_ssi_fiq_base:
137imx_ssi_fiq_base:
138		.word 0x0
139.L_imx_ssi_fiq_rx_buffer:
140imx_ssi_fiq_rx_buffer:
141		.word 0x0
142.L_imx_ssi_fiq_tx_buffer:
143imx_ssi_fiq_tx_buffer:
144		.word 0x0
145.L_imx_ssi_fiq_end:
146imx_ssi_fiq_end:
147
148