98 lines
3.1 KiB
ArmAsm
98 lines
3.1 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/***************************************************************************
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* Copyright (C) 2019 by Andreas Bolsch *
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* andreas.bolsch@mni.thm.de *
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***************************************************************************/
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.text
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.syntax unified
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.cpu cortex-m0
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.thumb
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.thumb_func
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/* Params:
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* r0 - total count (bytes), crc32 (out)
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* r1 - flash page size
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* r2 - address offset into flash
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* r3 - QSPI io_base
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* Clobbered:
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* r4 - rp
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* r5 - address of QSPI_DR
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* r7 - tmp
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*/
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#include "../../../../src/flash/nor/stmqspi.h"
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.macro qspi_abort
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movs r5, #(1<<SPI_ABORT) /* abort bit mask */
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ldr r7, [r3, #QSPI_CR] /* get QSPI_CR register */
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orrs r7, r7, r5 /* set abort bit */
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str r7, [r3, #QSPI_CR] /* store new CR register */
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.endm
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.macro wait_busy
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0:
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ldr r7, [r3, #QSPI_SR] /* load status */
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lsrs r7, r7, #(SPI_BUSY+1) /* shift BUSY into C */
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bcs 0b /* loop until BUSY cleared */
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movs r7, #(1<<SPI_TCF) /* TCF bitmask */
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str r7, [r3, #QSPI_FCR] /* clear TCF flag */
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.endm
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start:
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subs r0, r0, #1 /* decrement count for DLR */
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subs r1, r1, #1 /* page size mask and for DLR */
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movs r4, #0x00 /* initialize crc */
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mvns r4, r4 /* to 0xFFFFFFFF */
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start_read:
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qspi_abort /* start in clean state */
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movs r5, #QSPI_DR /* load QSPI_DR address offset */
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adds r5, r5, r3 /* address of QSPI_DR */
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wait_busy
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mov r7, r2 /* get current start address */
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orrs r7, r7, r1 /* end of current page */
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subs r7, r7, r2 /* count-1 to end of page */
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cmp r7, r0 /* if this count <= remaining */
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bls write_dlr /* then read to end of page */
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mov r7, r0 /* else read all remaining */
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write_dlr:
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str r7, [r3, #QSPI_DLR] /* size-1 in DLR register */
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ldr r7, ccr_page_read /* CCR for page read */
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str r7, [r3, #QSPI_CCR] /* initiate transfer */
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str r2, [r3, #QSPI_AR] /* store SPI start address */
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ldr r7, [r3, #QSPI_SR] /* wait for command startup */
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ldr r6, =0x04C11DB7 /* CRC32 polynomial */
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read_loop:
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ldrb r7, [r5] /* read next byte from DR */
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lsls r7, r7, #24 /* shift into msb */
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eors r4, r4, r7
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.rept 8 /* unrolled bit loop */
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asrs r7, r4, #31 /* copy bit 31 into bits 0 to 31 */
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ands r7, r7, r6 /* r7 neg. -> CRC32XOR, pos. -> 0x0 */
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lsls r4, r4, #1 /* shift result */
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eors r4, r4, r7 /* eor by CRC32XOR or 0x0 */
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.endr
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adds r2, r2, #1 /* increment address */
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subs r0, r0, #1 /* decrement (count-1) */
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bmi exit /* stop if no data left */
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tst r2, r1 /* page end ? */
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bne read_loop /* if not, then next byte */
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page_end:
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bal start_read /* then next page */
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.pool
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exit:
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mvns r0, r4 /* invert to get final result */
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qspi_abort /* to idle state */
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.align 2 /* align to word, bkpt is 4 words */
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bkpt #0 /* before code end for exit_point */
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.align 2 /* align to word */
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.space 4 /* not used */
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ccr_page_read:
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.space 4 /* QSPI_CCR value for read command */
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.space 4 /* not used */
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.space 4 /* not used */
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