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spi: altera: Simplify altera_spi_txrx implementation for noirq case 

This patch simplifies the code and makes it better in readability.
Now the logic in the while loop is simply
"write to ALTERA_SPI_TXDATA then read from ALTERA_SPI_TXDATA".

There is a slightly logic change because now we avoid a read-write cycle when
hw->len is 0. Since the code in bitbang library will call bitbang->txrx_bufs()
only when t->len is not 0, this is not a problem.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Thomas Chou <thomas@wytron.com.tw>
Signed-off-by: Mark Brown <broonie@linaro.org>
This commit is contained in:
Axel Lin 2013-08-15 14:18:46 +08:00 committed by Mark Brown
parent d8dfad3876
commit 72be0ee42e
1 changed files with 4 additions and 11 deletions
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15
drivers/spi/spi-altera.c
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@ -150,12 +150,12 @@ static int altera_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
hw->imr &= ~ALTERA_SPI_CONTROL_IRRDY_MSK; hw->imr &= ~ALTERA_SPI_CONTROL_IRRDY_MSK;
writel(hw->imr, hw->base + ALTERA_SPI_CONTROL); writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
} else { } else {
/* send the first byte */ while (hw->count < hw->len) {
writel(hw_txbyte(hw, 0), hw->base + ALTERA_SPI_TXDATA);
while (1) {
unsigned int rxd; unsigned int rxd;
writel(hw_txbyte(hw, hw->count),
hw->base + ALTERA_SPI_TXDATA);
while (!(readl(hw->base + ALTERA_SPI_STATUS) & while (!(readl(hw->base + ALTERA_SPI_STATUS) &
ALTERA_SPI_STATUS_RRDY_MSK)) ALTERA_SPI_STATUS_RRDY_MSK))
cpu_relax(); cpu_relax();
@ -174,14 +174,7 @@ static int altera_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
} }
hw->count++; hw->count++;
if (hw->count < hw->len)
writel(hw_txbyte(hw, hw->count),
hw->base + ALTERA_SPI_TXDATA);
else
break;
} }
} }
return hw->count * hw->bytes_per_word; return hw->count * hw->bytes_per_word;