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spi: sh_qspi: Make use of the 32byte FIFO

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The QSPI controller on RCar Gen2 has 32byte FIFO. Instead of doing
the SPI transmission 1 byte at time, if there is a 32byte chunk of
data to be transferred, fill the FIFO completely and then transfer
the data to/from the FIFO. This increases the SPI NOR access speed
significantly.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
This commit is contained in:
Marek Vasut 2018-04-10 16:43:47 +02:00 committed by Marek Vasut
parent 9573db654d
commit ea5512eb09
1 changed files with 24 additions and 10 deletions
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34
drivers/spi/sh_qspi.c
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@ -36,6 +36,8 @@
SPCMD_BRDV0
#define SPBFCR_TXRST BIT(7)
#define SPBFCR_RXRST BIT(6)
#define SPBFCR_TXTRG 0x30
#define SPBFCR_RXTRG 0x07
/* SH QSPI register set */
struct sh_qspi_regs {
@ -201,8 +203,8 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
void *din, unsigned long flags)
{
struct sh_qspi_slave *ss = to_sh_qspi(slave);
u32 nbyte;
int ret = 0;
u32 nbyte, chunk;
int i, ret = 0;
u8 dtdata = 0, drdata;
u8 *tdata = &dtdata, *rdata = &drdata;
u32 *spbmul0 = &ss->regs->spbmul0;
@ -237,26 +239,38 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
rdata = din;
while (nbyte > 0) {
/*
* Check if there is 32 Byte chunk and if there is, transfer
* it in one burst, otherwise transfer on byte-by-byte basis.
*/
chunk = (nbyte >= 32) ? 32 : 1;
clrsetbits_8(&ss->regs->spbfcr, SPBFCR_TXTRG | SPBFCR_RXTRG,
chunk == 32 ? SPBFCR_TXTRG | SPBFCR_RXTRG : 0);
ret = wait_for_bit_8(&ss->regs->spsr, SPSR_SPTEF,
true, 1000, true);
if (ret)
return ret;
writeb(*tdata, (u8 *)(&ss->regs->spdr));
for (i = 0; i < chunk; i++) {
writeb(*tdata, &ss->regs->spdr);
if (dout != NULL)
tdata++;
}
ret = wait_for_bit_8(&ss->regs->spsr, SPSR_SPRFF,
true, 1000, true);
if (ret)
return ret;
*rdata = readb((u8 *)(&ss->regs->spdr));
for (i = 0; i < chunk; i++) {
*rdata = readb(&ss->regs->spdr);
if (din != NULL)
rdata++;
}
if (dout != NULL)
tdata++;
if (din != NULL)
rdata++;
nbyte--;
nbyte -= chunk;
}
if (flags & SPI_XFER_END)