LXR linux/arch/arm/mach-imx/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
 145