Hardware
/
litex
mirror of https://github.com/enjoy-digital/litex.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

spisdcard: revert to 8-bit SPI, optimize spisdcardreceive_block and reduce clk to 12.5MHz for now.

This commit is contained in:
Florent Kermarrec 2020-07-17 11:58:26 +02:00
parent 8143f1a08b
commit 754f140a9d
2 changed files with 27 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
litex/soc/integration/soc.py
View File

@ -1263,7 +1263,7 @@ class LiteXSoC(SoC):
pads = self.platform.request(name)
if hasattr(pads, "rst"):
self.comb += pads.rst.eq(0)
spisdcard = SPIMaster(pads, 32, self.sys_clk_freq, spi_clk_freq, mode="aligned")
spisdcard = SPIMaster(pads, 8, self.sys_clk_freq, spi_clk_freq)
spisdcard.add_clk_divider()
setattr(self.submodules, name, spisdcard)
self.add_csr(name)

44
litex/soc/software/liblitesdcard/spisdcard.c
View File

@ -24,20 +24,25 @@
#define SPISDCARD_CLK_FREQ_INIT 400000
#endif
#ifndef SPISDCARD_CLK_FREQ
#define SPISDCARD_CLK_FREQ 16000000
#define SPISDCARD_CLK_FREQ 12500000
#endif
/*-----------------------------------------------------------------------*/
/* Helpers */
/*-----------------------------------------------------------------------*/
#define max(x, y) (((x) > (y)) ? (x) : (y))
#define min(x, y) (((x) < (y)) ? (x) : (y))
/*-----------------------------------------------------------------------*/
/* SPI Master low-level functions */
/*-----------------------------------------------------------------------*/
static void spi_set_clk_freq(uint32_t clk_freq) {
uint32_t divider;
divider = CONFIG_CLOCK_FREQUENCY/clk_freq + 1;
if (divider >= 65535) /* 16-bit hardware divider */
divider = 65535;
if (divider <= 2) /* At least half CPU speed */
divider = 2;
divider = CONFIG_CLOCK_FREQUENCY/clk_freq;
divider = max(divider, 2);
divider = min(divider, 256);
#ifdef SPISDCARD_DEBUG
printf("Setting SDCard clk freq to ");
if (clk_freq > 1000000)
@ -125,7 +130,8 @@ static void busy_wait_us(unsigned int us)
}
static uint8_t spisdcardreceive_block(uint8_t *buf) {
uint8_t i;
uint16_t i;
uint8_t done;
uint32_t timeout;
/* Wait 100ms for a start of block */
@ -140,17 +146,19 @@ static uint8_t spisdcardreceive_block(uint8_t *buf) {
return 0;
/* Receive block */
spisdcard_mosi_write(0xffffffff);
for (i=0; i<128; i++) {
uint32_t word;
spisdcard_control_write(32*SPI_LENGTH | SPI_START);
while(spisdcard_status_read() != SPI_DONE);
word = spisdcard_miso_read();
buf[0] = (word >> 24) & 0xff;
buf[1] = (word >> 16) & 0xff;
buf[2] = (word >> 8) & 0xff;
buf[3] = (word >> 0) & 0xff;
buf += 4;
spisdcard_mosi_write(0xff);
i = 0;
for (;;) {
done = spisdcard_status_read() & SPI_DONE;
if (done) {
spisdcard_control_write(8*SPI_LENGTH | SPI_START);
*buf = spisdcard_miso_read();
if (i == 512)
break;
if (i != 0)
buf++;
i++;
}
}
/* Discard CRC */