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software/libsdcard/spisdcard: add and use busy_wait_us to optimize speed.

This commit is contained in:
Florent Kermarrec 2020-06-10 09:15:12 +02:00
parent dae15511a4
commit 5beba178f2
1 changed files with 13 additions and 3 deletions
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16
litex/soc/software/liblitesdcard/spisdcard.c
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@ -114,15 +114,25 @@ static void spisdcardread_bytes(uint8_t* buf, uint16_t n) {
/* SPI SDCard blocks Xfer functions */
/*-----------------------------------------------------------------------*/
static void busy_wait_us(unsigned int us)
{
timer0_en_write(0);
timer0_reload_write(0);
timer0_load_write(CONFIG_CLOCK_FREQUENCY/1000000*us);
timer0_en_write(1);
timer0_update_value_write(1);
while(timer0_value_read()) timer0_update_value_write(1);
}
static uint8_t spisdcardreceive_block(uint8_t *buf) {
uint16_t timeout;
uint32_t timeout;
/* Wait 100ms for a start of block */
timeout = 100;
timeout = 100000;
while(timeout > 0) {
if (spi_xfer(0xff) == 0xfe)
break;
busy_wait(1);
busy_wait_us(1);
timeout--;
}
if (timeout == 0)