7095b95654
Because FIQ handlers get copied straight into the vectors page to the FIQ vector entry point, FIQ handlers in a Thumb-2 kernel must start in Thumb-2. A Thumb-2 kernel enters all exception vectors in Thumb-2. This patch adapts the mxc SSI FIQ code suitable for a Thumb-2 kernel. The code contained use of r13 (sp) which isn't allowed in Thumb-2. r11 and r13 have been swapped throughout the file to work around this. Currently, the way that the function to be copied is located using labels is a bit ugly: we cannot annotate the FIQ handler properly as a Thumb-2 function, because this would set bit 0 of the label address seen by the linker, causing off-by-one errors when copying the function. Ideally, the copy would be done with fncpy(), but this would require changes to the common set_fiq_handler() function. For now, we don't touch this. References to locally-defined global symbols with adr and ldr may not be accepted by the assembler in Thumb-2. Local shadow symbols are added to work around this. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
148 lines
2.9 KiB
ArmAsm
148 lines
2.9 KiB
ArmAsm
/*
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* Copyright (C) 2009 Sascha Hauer <s.hauer@pengutronix.de>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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/*
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* r8 = bit 0-15: tx offset, bit 16-31: tx buffer size
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* r9 = bit 0-15: rx offset, bit 16-31: rx buffer size
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*/
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#define SSI_STX0 0x00
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#define SSI_SRX0 0x08
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#define SSI_SISR 0x14
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#define SSI_SIER 0x18
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#define SSI_SACNT 0x38
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#define SSI_SACNT_AC97EN (1 << 0)
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#define SSI_SIER_TFE0_EN (1 << 0)
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#define SSI_SISR_TFE0 (1 << 0)
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#define SSI_SISR_RFF0 (1 << 2)
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#define SSI_SIER_RFF0_EN (1 << 2)
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.text
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.global imx_ssi_fiq_start
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.global imx_ssi_fiq_end
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.global imx_ssi_fiq_base
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.global imx_ssi_fiq_rx_buffer
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.global imx_ssi_fiq_tx_buffer
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/*
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* imx_ssi_fiq_start is _intentionally_ not marked as a function symbol
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* using ENDPROC(). imx_ssi_fiq_start and imx_ssi_fiq_end are used to
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* mark the function body so that it can be copied to the FIQ vector in
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* the vectors page. imx_ssi_fiq_start should only be called as the result
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* of an FIQ: calling it directly will not work.
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*/
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imx_ssi_fiq_start:
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ldr r12, .L_imx_ssi_fiq_base
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/* TX */
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ldr r13, .L_imx_ssi_fiq_tx_buffer
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/* shall we send? */
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ldr r11, [r12, #SSI_SIER]
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tst r11, #SSI_SIER_TFE0_EN
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beq 1f
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/* TX FIFO empty? */
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ldr r11, [r12, #SSI_SISR]
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tst r11, #SSI_SISR_TFE0
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beq 1f
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mov r10, #0x10000
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sub r10, #1
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and r10, r10, r8 /* r10: current buffer offset */
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add r13, r13, r10
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ldrh r11, [r13]
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strh r11, [r12, #SSI_STX0]
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ldrh r11, [r13, #2]
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strh r11, [r12, #SSI_STX0]
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ldrh r11, [r13, #4]
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strh r11, [r12, #SSI_STX0]
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ldrh r11, [r13, #6]
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strh r11, [r12, #SSI_STX0]
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add r10, #8
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lsr r11, r8, #16 /* r11: buffer size */
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cmp r10, r11
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lslgt r8, r11, #16
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addle r8, #8
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1:
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/* RX */
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/* shall we receive? */
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ldr r11, [r12, #SSI_SIER]
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tst r11, #SSI_SIER_RFF0_EN
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beq 1f
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/* RX FIFO full? */
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ldr r11, [r12, #SSI_SISR]
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tst r11, #SSI_SISR_RFF0
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beq 1f
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ldr r13, .L_imx_ssi_fiq_rx_buffer
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mov r10, #0x10000
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sub r10, #1
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and r10, r10, r9 /* r10: current buffer offset */
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add r13, r13, r10
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ldr r11, [r12, #SSI_SACNT]
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tst r11, #SSI_SACNT_AC97EN
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ldr r11, [r12, #SSI_SRX0]
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strh r11, [r13]
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ldr r11, [r12, #SSI_SRX0]
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strh r11, [r13, #2]
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/* dummy read to skip slot 12 */
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ldrne r11, [r12, #SSI_SRX0]
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ldr r11, [r12, #SSI_SRX0]
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strh r11, [r13, #4]
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ldr r11, [r12, #SSI_SRX0]
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strh r11, [r13, #6]
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/* dummy read to skip slot 12 */
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ldrne r11, [r12, #SSI_SRX0]
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add r10, #8
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lsr r11, r9, #16 /* r11: buffer size */
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cmp r10, r11
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lslgt r9, r11, #16
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addle r9, #8
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1:
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@ return from FIQ
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subs pc, lr, #4
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.align
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.L_imx_ssi_fiq_base:
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imx_ssi_fiq_base:
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.word 0x0
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.L_imx_ssi_fiq_rx_buffer:
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imx_ssi_fiq_rx_buffer:
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.word 0x0
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.L_imx_ssi_fiq_tx_buffer:
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imx_ssi_fiq_tx_buffer:
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.word 0x0
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.L_imx_ssi_fiq_end:
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imx_ssi_fiq_end:
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