mirror of
https://github.com/hsoft/collapseos.git
synced 2024-09-07 20:28:45 +10:00
208 lines
5.1 KiB
C
208 lines
5.1 KiB
C
#include <stdio.h>
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#include "sdc.h"
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// Add data to crc with polynomial 0x1021
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// https://stackoverflow.com/a/23726131
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static uint16_t crc16(uint16_t crc, uint8_t data)
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{
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uint8_t x = crc >> 8 ^ data;
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x ^= x>>4;
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crc = (crc << 8) ^ ((uint16_t)(x << 12)) ^ ((uint16_t)(x <<5)) ^ ((uint16_t)x);
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return crc;
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}
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void sdc_init(SDC *sdc)
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{
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sdc->selected = false;
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sdc->initstat = 0;
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sdc->recvidx = 0;
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sdc->sendidx = -1;
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sdc->resp = 0xff;
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sdc->fp = NULL;
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sdc->cmd17bytes = -1;
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sdc->cmd24bytes = -2;
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}
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void sdc_cslow(SDC *sdc)
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{
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sdc->selected = true;
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}
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void sdc_cshigh(SDC *sdc)
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{
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sdc->selected = false;
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}
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void sdc_spi_wr(SDC *sdc, uint8_t val)
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{
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if (!sdc->selected) {
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return;
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}
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sdc->resp = 0xff;
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if (sdc->initstat < 8) {
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// not woken yet.
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sdc->initstat++;
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return;
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}
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if (sdc->sendidx >= 0) {
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sdc->resp = sdc->sendbuf[sdc->sendidx++];
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if (sdc->sendidx == 5) {
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sdc->sendidx = -1;
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}
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return;
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}
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if (sdc->cmd17bytes >= 0) {
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if (sdc->fp) {
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sdc->resp = getc(sdc->fp);
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}
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sdc->crc16 = crc16(sdc->crc16, sdc->resp);
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sdc->cmd17bytes++;
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if (sdc->cmd17bytes == 512) {
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sdc->sendbuf[3] = sdc->crc16 >> 8;
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sdc->sendbuf[4] = sdc->crc16 & 0xff;
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sdc->sendidx = 3;
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sdc->cmd17bytes = -1;
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}
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return;
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}
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if (sdc->cmd24bytes == -1) {
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if (val == 0xff) {
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// it's ok to receive idle bytes before the data token.
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return;
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}
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if (val == 0xfe) {
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// data token, good
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sdc->cmd24bytes = 0;
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} else {
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// something is wrong, cancel cmd24
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sdc->cmd24bytes = -2;
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}
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return;
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}
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if (sdc->cmd24bytes >= 0) {
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if (sdc->cmd24bytes < 512) {
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if (sdc->fp) {
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putc(val, sdc->fp);
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}
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sdc->crc16 = crc16(sdc->crc16, val);
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} else if (sdc->cmd24bytes == 512) {
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// CRC MSB
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if (val == (sdc->crc16>>8)) {
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fprintf(stderr, "Good CRC16 MSB\n");
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} else {
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fprintf(stderr, "Bad CRC16 MSB\n");
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}
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} else {
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if (val == (sdc->crc16&0xff)) {
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fprintf(stderr, "Good CRC16 LSB\n");
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} else {
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fprintf(stderr, "Bad CRC16 LSB\n");
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}
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// valid response for CMD24
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sdc->sendbuf[4] = 0x05;
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sdc->sendidx = 4;
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sdc->cmd24bytes = -3;
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}
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sdc->cmd24bytes++;
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return;
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}
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if ((sdc->recvidx == 0) && ((val > 0x7f) || (val < 0x40))) {
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// not a command
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return;
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}
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sdc->recvbuf[sdc->recvidx++] = val;
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if (sdc->recvidx < 6) {
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// incomplete command
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return;
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}
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// Command complete
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val &= 0x3f;
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sdc->recvidx = 0;
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uint8_t *b = sdc->recvbuf;
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uint8_t cmd = b[0] & 0x3f;
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uint16_t arg1 = (b[1] << 8) | b[2];
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uint16_t arg2 = (b[3] << 8) | b[4];
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// printf("cmd %02x %04x %04x\n", cmd, arg1, arg2);
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if (sdc->initstat == 8) {
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// At this stage, we're expecting CMD0
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if (cmd == 0) {
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sdc->initstat++;
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sdc->sendbuf[4] = 0x01;
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sdc->sendidx = 4;
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}
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return;
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}
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if (sdc->initstat == 9) {
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// At this stage, we're expecting CMD8 with 0x1aa arg2
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if ((cmd == 8) && (arg2 == 0x01aa)) {
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sdc->initstat++;
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sdc->sendbuf[0] = 0x01;
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sdc->sendbuf[1] = 0;
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sdc->sendbuf[2] = 0;
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sdc->sendbuf[3] = 0x01;
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sdc->sendbuf[4] = 0xaa;
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sdc->sendidx = 0;
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} else {
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sdc-> initstat = 8;
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}
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return;
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}
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if (sdc->initstat == 10) {
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// At this stage, we're expecting CMD55
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if (cmd == 55) {
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sdc->initstat++;
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sdc->sendbuf[4] = 0x01;
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sdc->sendidx = 4;
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} else {
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sdc->initstat = 8;
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}
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return;
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}
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if (sdc->initstat == 11) {
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// At this stage, we're expecting CMD41
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if ((cmd == 41) && (arg1 == 0x4000)) {
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sdc->initstat++;
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sdc->sendbuf[4] = 0x00;
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sdc->sendidx = 4;
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} else {
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sdc->initstat = 8;
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}
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return;
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}
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// We have a fully initialized card.
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if (cmd == 17) {
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if (sdc->fp) {
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fseek(sdc->fp, arg2*512, SEEK_SET);
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}
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sdc->sendbuf[3] = 0x00;
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// data token
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sdc->sendbuf[4] = 0xfe;
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sdc->sendidx = 3;
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sdc->cmd17bytes = 0;
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sdc->crc16 = 0;
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return;
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}
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if (cmd == 24) {
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fprintf(stderr, "cmd24\n");
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if (sdc->fp) {
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fseek(sdc->fp, arg2*512, SEEK_SET);
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}
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sdc->sendbuf[4] = 0x00;
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sdc->sendidx = 4;
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sdc->cmd24bytes = -1;
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sdc->crc16 = 0;
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return;
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}
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// Simulate success for any unknown command.
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sdc->sendbuf[4] = 0x00;
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sdc->sendidx = 4;
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}
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uint8_t sdc_spi_rd(SDC *sdc)
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{
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if (!sdc->selected) {
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return 0xff;
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}
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return sdc->resp;
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}
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