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MX28: SPI: Refactor spi_xfer a bit

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This makes it easier to adapt for addition of DMA support.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: Otavio Salvador <otavio@ossystems.com.br>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Wolfgang Denk <wd@denx.de>
This commit is contained in:
Marek Vasut 2012-07-09 00:48:31 +00:00 • committed by Albert ARIBAUD
parent e972d72bd7
commit c7065fa824
1 changed files with 22 additions and 10 deletions
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32
drivers/spi/mxs_spi.c
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@ -146,21 +146,33 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
struct mxs_spi_slave *mxs_slave = to_mxs_slave(slave); struct mxs_spi_slave *mxs_slave = to_mxs_slave(slave);
struct mx28_ssp_regs *ssp_regs = mxs_slave->regs; struct mx28_ssp_regs *ssp_regs = mxs_slave->regs;
int len = bitlen / 8; int len = bitlen / 8;
const char *tx = dout;
char *rx = din;
char dummy; char dummy;
int write = 0;
char *data = NULL;
if (bitlen == 0) { if (bitlen == 0) {
if (flags & SPI_XFER_END) { if (flags & SPI_XFER_END) {
rx = &dummy; din = (void *)&dummy;
len = 1; len = 1;
} else } else
return 0; return 0;
} }
if (!rx && !tx) /* Half-duplex only */
if (din && dout)
return -EINVAL;
/* No data */
if (!din && !dout)
return 0; return 0;
if (dout) {
data = (char *)dout;
write = 1;
} else if (din) {
data = (char *)din;
write = 0;
}
if (flags & SPI_XFER_BEGIN) if (flags & SPI_XFER_BEGIN)
mxs_spi_start_xfer(ssp_regs); mxs_spi_start_xfer(ssp_regs);
@ -171,7 +183,7 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
if ((flags & SPI_XFER_END) && !len) if ((flags & SPI_XFER_END) && !len)
mxs_spi_end_xfer(ssp_regs); mxs_spi_end_xfer(ssp_regs);
if (tx) if (write)
writel(SSP_CTRL0_READ, &ssp_regs->hw_ssp_ctrl0_clr); writel(SSP_CTRL0_READ, &ssp_regs->hw_ssp_ctrl0_clr);
else else
writel(SSP_CTRL0_READ, &ssp_regs->hw_ssp_ctrl0_set); writel(SSP_CTRL0_READ, &ssp_regs->hw_ssp_ctrl0_set);
@ -184,20 +196,20 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
return -ETIMEDOUT; return -ETIMEDOUT;
} }
if (tx) if (write)
writel(*tx++, &ssp_regs->hw_ssp_data); writel(*data++, &ssp_regs->hw_ssp_data);
writel(SSP_CTRL0_DATA_XFER, &ssp_regs->hw_ssp_ctrl0_set); writel(SSP_CTRL0_DATA_XFER, &ssp_regs->hw_ssp_ctrl0_set);
if (rx) { if (!write) {
if (mx28_wait_mask_clr(&ssp_regs->hw_ssp_status_reg, if (mx28_wait_mask_clr(&ssp_regs->hw_ssp_status_reg,
SSP_STATUS_FIFO_EMPTY, MXS_SPI_MAX_TIMEOUT)) { SSP_STATUS_FIFO_EMPTY, MXS_SPI_MAX_TIMEOUT)) {
printf("MXS SPI: Timeout waiting for data\n"); printf("MXS SPI: Timeout waiting for data\n");
return -ETIMEDOUT; return -ETIMEDOUT;
} }
*rx = readl(&ssp_regs->hw_ssp_data); *data = readl(&ssp_regs->hw_ssp_data);
rx++; data++;
} }
if (mx28_wait_mask_clr(&ssp_regs->hw_ssp_ctrl0_reg, if (mx28_wait_mask_clr(&ssp_regs->hw_ssp_ctrl0_reg,