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/***************************************************************************
* Copyright (C) 2012 by George Harris *
* george@luminairecoffee.com *
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
* This program is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU General Public License for more details. *
* *
* You should have received a copy of the GNU General Public License *
* along with this program; if not, write to the *
* Free Software Foundation, Inc., *
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. *
***************************************************************************/
.text
.syntax unified
.cpu cortex-m3
.thumb
.thumb_func
/*
* Params :
* r0 = start address, status (out)
* r1 = count
* r2 = erase command
* r3 = block size
*/
#define SSP_BASE_HIGH 0x4008
#define SSP_BASE_LOW 0x3000
#define SSP_CR0_OFFSET 0x00
#define SSP_CR1_OFFSET 0x04
#define SSP_DATA_OFFSET 0x08
#define SSP_CPSR_OFFSET 0x10
#define SSP_SR_OFFSET 0x0c
#define SSP_CLOCK_BASE_HIGH 0x4005
#define SSP_CLOCK_BASE_LOW 0x0000
#define SSP_BRANCH_CLOCK_BASE_HIGH 0x4005
#define SSP_BRANCH_CLOCK_BASE_LOW 0x2000
#define SSP_BASE_CLOCK_OFFSET 0x94
#define SSP_BRANCH_CLOCK_OFFSET 0x700
#define IOCONFIG_BASE_HIGH 0x4008
#define IOCONFIG_BASE_LOW 0x6000
#define IOCONFIG_SCK_OFFSET 0x18c
#define IOCONFIG_HOLD_OFFSET 0x190
#define IOCONFIG_WP_OFFSET 0x194
#define IOCONFIG_MISO_OFFSET 0x198
#define IOCONFIG_MOSI_OFFSET 0x19c
#define IOCONFIG_CS_OFFSET 0x1a0
#define IO_BASE_HIGH 0x400f
#define IO_BASE_LOW 0x4000
#define IO_CS_OFFSET 0xab
#define IODIR_BASE_HIGH 0x400f
#define IODIR_BASE_LOW 0x6000
#define IO_CS_DIR_OFFSET 0x14
setup: /* Initialize SSP pins and module */
mov.w r10, #IOCONFIG_BASE_LOW
movt r10, #IOCONFIG_BASE_HIGH
mov.w r8, #0xea
str.w r8, [r10, #IOCONFIG_SCK_OFFSET] /* Configure SCK pin function */
mov.w r8, #0x40
str.w r8, [r10, #IOCONFIG_HOLD_OFFSET] /* Configure /HOLD pin function */
mov.w r8, #0x40
str.w r8, [r10, #IOCONFIG_WP_OFFSET] /* Configure /WP pin function */
mov.w r8, #0xed
str.w r8, [r10, #IOCONFIG_MISO_OFFSET] /* Configure MISO pin function */
mov.w r8, #0xed
str.w r8, [r10, #IOCONFIG_MOSI_OFFSET] /* Configure MOSI pin function */
mov.w r8, #0x44
str.w r8, [r10, #IOCONFIG_CS_OFFSET] /* Configure CS pin function */
mov.w r10, #IODIR_BASE_LOW
movt r10, #IODIR_BASE_HIGH
mov.w r8, #0x800
str r8, [r10, #IO_CS_DIR_OFFSET] /* Set CS as output */
mov.w r10, #IO_BASE_LOW
movt r10, #IO_BASE_HIGH
mov.w r8, #0xff
str.w r8, [r10, #IO_CS_OFFSET] /* Set CS high */
mov.w r10, #SSP_CLOCK_BASE_LOW
movt r10, #SSP_CLOCK_BASE_HIGH
mov.w r8, #0x0000
movt r8, #0x0100
str.w r8, [r10, #SSP_BASE_CLOCK_OFFSET] /* Configure SSP0 base clock (use 12 MHz IRC) */
mov.w r10, #SSP_BRANCH_CLOCK_BASE_LOW
movt r10, #SSP_BRANCH_CLOCK_BASE_HIGH
mov.w r8, #0x01
str.w r8, [r10, #SSP_BRANCH_CLOCK_OFFSET] /* Configure (enable) SSP0 branch clock */
mov.w r10, #SSP_BASE_LOW
movt r10, #SSP_BASE_HIGH
mov.w r8, #0x07
str.w r8, [r10, #SSP_CR0_OFFSET] /* Set clock postscale */
mov.w r8, #0x02
str.w r8, [r10, #SSP_CPSR_OFFSET] /* Set clock prescale */
str.w r8, [r10, #SSP_CR1_OFFSET] /* Enable SSP in SPI mode */
write_enable:
bl cs_down
mov.w r9, #0x06 /* Send the write enable command */
bl write_data
bl cs_up
bl cs_down
mov.w r9, #0x05 /* Get status register */
bl write_data
mov.w r9, #0x00 /* Dummy data to clock in status */
bl write_data
bl cs_up
tst r9, #0x02 /* If the WE bit isn't set, we have a problem. */
beq error
erase:
bl cs_down
mov.w r9, r2 /* Send the erase command */
bl write_data
write_address:
lsr r9, r0, #16 /* Send the current 24-bit write address, MSB first */
bl write_data
lsr r9, r0, #8
bl write_data
mov.w r9, r0
bl write_data
bl cs_up
wait_flash_busy: /* Wait for the flash to finish the previous erase */
bl cs_down
mov.w r9, #0x05 /* Get status register */
bl write_data
mov.w r9, #0x00 /* Dummy data to clock in status */
bl write_data
bl cs_up
tst r9, #0x01 /* If it isn't done, keep waiting */
bne wait_flash_busy
subs r1, r1, #1 /* decrement count */
cbz r1, exit /* Exit if we have written everything */
add r0, r3 /* Move the address up by the block size */
b write_enable /* Start a new block erase */
write_data: /* Send/receive 1 byte of data over SSP */
mov.w r10, #SSP_BASE_LOW
movt r10, #SSP_BASE_HIGH
str.w r9, [r10, #SSP_DATA_OFFSET] /* Write supplied data to the SSP data reg */
wait_transmit:
ldr r9, [r10, #SSP_SR_OFFSET] /* Check SSP status */
tst r9, #0x0010 /* Check if BSY bit is set */
bne wait_transmit /* If still transmitting, keep waiting */
ldr r9, [r10, #SSP_DATA_OFFSET] /* Load received data */
bx lr /* Exit subroutine */
cs_up:
mov.w r8, #0xff
b cs_write
cs_down:
mov.w r8, #0x0000
cs_write:
mov.w r10, #IO_BASE_LOW
movt r10, #IO_BASE_HIGH
str.w r8, [r10, #IO_CS_OFFSET]
bx lr
error:
movs r0, #0
exit:
bkpt #0x00
.end
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