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/**
* @file sdcard.c
* Provides a basic library for accessing an SD card
*
* Copyright (C) 2018 Clyne Sullivan
*
* 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 3 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, see <https://www.gnu.org/licenses/>.
*/
#include <clock.h>
#include <gpio.h>
#include <heap.h>
#include <sdcard.h>
#include <string.h>
#define SCK GPIO_PORT(A, 5)
#define SO GPIO_PORT(A, 6)
#define SI GPIO_PORT(A, 7)
#define CS GPIO_PORT(B, 6)
typedef struct {
uint8_t cmd;
uint32_t arg;
uint8_t crc;
} __attribute__ ((packed)) sdcmd_t;
typedef struct {
uint8_t zero :1;
uint8_t param :1;
uint8_t address :1;
uint8_t erase :1;
uint8_t crc :1;
uint8_t badcmd :1;
uint8_t ereset :1;
uint8_t idle :1;
} __attribute__ ((packed)) r1_t;
void flash_out(uint8_t byte)
{
for (int i = 0; i < 8; i++) {
gpio_dout(SI, byte & (1 << (7 - i)));
gpio_dout(SCK, 1);
gpio_dout(SCK, 0);
}
}
uint8_t flash_in(void)
{
uint8_t byte = 0;
for (int i = 0; i < 8; i++) {
if (gpio_din(SO))
byte |= 1 << (7 - i);
gpio_dout(SCK, 1);
gpio_dout(SCK, 0);
}
return byte;
}
void sd_delay(void)
{
gpio_dout(SI, 1);
uint8_t so;
int i = 0;
do {
so = flash_in();
if (i < 8)
i++;
} while (i < 8 || so != 0xFF);
}
uint8_t sd_send_cmd(uint8_t cmd, uint32_t arg)
{
sdcmd_t cmdp;
cmdp.cmd = (cmd & 0x3F) | 0x40;
cmdp.arg = arg;
sd_delay();
flash_out(cmdp.cmd);
flash_out(cmdp.arg >> 24);
flash_out(cmdp.arg >> 16);
flash_out(cmdp.arg >> 8);
flash_out(cmdp.arg);
flash_out(cmd == 8 ? 0x87 : 0x95);
// wait for a zero
gpio_dout(SI, 1);
uint8_t r1;
do {
r1 = flash_in();
} while (r1 & 0x80);
return r1;
}
void sd_init(void)
{
gpio_mode(SCK, OUTPUT);
gpio_mode(SI, OUTPUT);
gpio_mode(CS, OUTPUT);
gpio_mode(SO, OUTPUT);
gpio_speed(SCK, VERYHIGH);
gpio_speed(SI, VERYHIGH);
gpio_speed(SO, VERYHIGH);
gpio_speed(CS, VERYHIGH);
gpio_pupd(SCK, PULLUP);
gpio_pupd(SI, PULLUP);
gpio_pupd(SO, PULLUP);
gpio_pupd(CS, PULLUP);
gpio_dout(SO, 0);
gpio_mode(SO, INPUT);
gpio_dout(CS, 1);
gpio_dout(SCK, 0);
gpio_dout(SI, 1);
// init? cs and si are high
delay(10);
sd_delay();
// pull cs low, send cmd0
gpio_dout(CS, 0);
uint8_t resp = sd_send_cmd(0, 0);
sd_delay();
gpio_dout(CS, 1);
if (resp != 0x01)
while (1);
// do cmd8
delay(10);
gpio_dout(CS, 0);
resp = sd_send_cmd(8, 0x1AA);
uint8_t ocr[4];
for (int i = 0; i < 4; i++)
ocr[i] = flash_in();
sd_delay();
gpio_dout(CS, 1);
(void)ocr;
// initialize
do {
// cmd55
gpio_dout(CS, 0);
resp = sd_send_cmd(55, 0);
sd_delay();
gpio_dout(CS, 1);
delay(10);
// acmd41
gpio_dout(CS, 0);
resp = sd_send_cmd(41, 0x40000000);
sd_delay();
gpio_dout(CS, 1);
} while (resp != 0x00);
// set block length
gpio_dout(CS, 0);
resp = sd_send_cmd(16, 512);
sd_delay();
gpio_dout(CS, 1);
}
uint8_t *sd_read_block(uint8_t *buf, uint32_t lba)
{
if (buf == 0)
return 0;
// send command
gpio_dout(CS, 0);
if (sd_send_cmd(17, lba) != 0)
return 0;
// wait for block
gpio_dout(SI, 1);
uint8_t byte;
do byte = flash_in();
while (byte == 0xFF);
if (byte != 0xFE)
return 0;
// get block
uint32_t i = 0;
for (i = 0; i < 512; i++)
buf[i] = flash_in();
sd_delay();
gpio_dout(CS, 1);
return buf;
}
uint8_t *sd_read(uint8_t *buf, uint32_t lba, uint32_t count)
{
if (buf == 0)
return 0;
uint8_t *block_buf = malloc(512);
uint32_t i = 0;
while (count > 0) {
sd_read_block(block_buf, lba);
memcpy(buf + i, block_buf, (count < 512) ? count : 512);
if (count < 512)
count = 0;
else
count -= 512;
i += 512;
lba++;
}
free(block_buf);
return buf;
}
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