On 02/03/2011 02:37 AM, Thomas Chou wrote:
> This patch adds support of OpenCores tiny SPI driver.
>
> http://opencores.org/project,tiny_spi
>
> +static int tiny_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
> +{
> + struct tiny_spi *hw = tiny_spi_to_hw(spi);
> + const u8 *txp = t->tx_buf;
> + u8 *rxp = t->rx_buf;
> + unsigned int i;
> +
> + if (hw->irq>= 0) {
> + /* use intrrupt driven data transfer */
> + hw->len = t->len;
> + hw->txp = t->tx_buf;
> + hw->rxp = t->rx_buf;
> + hw->txc = 0;
> + hw->rxc = 0;
> +
> + /* send the first byte */
> + if (t->len> 1) {
> + writeb(hw->txp ? *hw->txp++ : 0,
> + hw->base + TINY_SPI_TXDATA);
> + hw->txc++;
> + writeb(hw->txp ? *hw->txp++ : 0,
> + hw->base + TINY_SPI_TXDATA);
> + hw->txc++;
> + writeb(TINY_SPI_STATUS_TXR, hw->base + TINY_SPI_STATUS);
> + } else {
> + writeb(hw->txp ? *hw->txp++ : 0,
> + hw->base + TINY_SPI_TXDATA);
> + hw->txc++;
> + writeb(TINY_SPI_STATUS_TXE, hw->base + TINY_SPI_STATUS);
> + }
> +
> + wait_for_completion(&hw->done);
> + } else if (txp&& rxp) {
> + /* we need to tighten the transfer loop */
> + writeb(*txp++, hw->base + TINY_SPI_TXDATA);
> + if (t->len> 1) {
> + writeb(*txp++, hw->base + TINY_SPI_TXDATA);
> + for (i = 2; i< t->len; i++) {
> + u8 rx, tx = *txp++;
> + while (!(readb(hw->base + TINY_SPI_STATUS)&
> + TINY_SPI_STATUS_TXR))
> + cpu_relax();
Putting the read status, cpu releax in an inline function would make this
function a lot easier to read.
> + rx = readb(hw->base + TINY_SPI_TXDATA);
> + writeb(tx, hw->base + TINY_SPI_TXDATA);
> + *rxp++ = rx;
> + }
> + while (!(readb(hw->base + TINY_SPI_STATUS)&
> + TINY_SPI_STATUS_TXR))
> + cpu_relax();
> + *rxp++ = readb(hw->base + TINY_SPI_TXDATA);
> + }
> + while (!(readb(hw->base + TINY_SPI_STATUS)&
> + TINY_SPI_STATUS_TXE))
> + cpu_relax();
> + *rxp++ = readb(hw->base + TINY_SPI_RXDATA);
> + } else if (rxp) {
> + writeb(0, hw->base + TINY_SPI_TXDATA);
> + if (t->len> 1) {
> + writeb(0,
> + hw->base + TINY_SPI_TXDATA);
> + for (i = 2; i< t->len; i++) {
> + u8 rx;
> + while (!(readb(hw->base + TINY_SPI_STATUS)&
> + TINY_SPI_STATUS_TXR))
> + cpu_relax();
> + rx = readb(hw->base + TINY_SPI_TXDATA);
> + writeb(0,
> + hw->base + TINY_SPI_TXDATA);
> + *rxp++ = rx;
> + }
> + while (!(readb(hw->base + TINY_SPI_STATUS)&
> + TINY_SPI_STATUS_TXR))
> + cpu_relax();
> + *rxp++ = readb(hw->base + TINY_SPI_TXDATA);
> + }
> + while (!(readb(hw->base + TINY_SPI_STATUS)&
> + TINY_SPI_STATUS_TXE))
> + cpu_relax();
> + *rxp++ = readb(hw->base + TINY_SPI_RXDATA);
> + } else if (txp) {
> + writeb(*txp++, hw->base + TINY_SPI_TXDATA);
> + if (t->len> 1) {
> + writeb(*txp++, hw->base + TINY_SPI_TXDATA);
> + for (i = 2; i< t->len; i++) {
> + u8 tx = *txp++;
> + while (!(readb(hw->base + TINY_SPI_STATUS)&
> + TINY_SPI_STATUS_TXR))
> + cpu_relax();
> + writeb(tx, hw->base + TINY_SPI_TXDATA);
> + }
> + }
> + while (!(readb(hw->base + TINY_SPI_STATUS)&
> + TINY_SPI_STATUS_TXE))
> + cpu_relax();
> + } else {
> + writeb(0, hw->base + TINY_SPI_TXDATA);
> + if (t->len> 1) {
> + writeb(0,
> + hw->base + TINY_SPI_TXDATA);
> + for (i = 2; i< t->len; i++) {
> + while (!(readb(hw->base + TINY_SPI_STATUS)&
> + TINY_SPI_STATUS_TXR))
> + cpu_relax();
> + writeb(0,
> + hw->base + TINY_SPI_TXDATA);
> + }
> + }
> + while (!(readb(hw->base + TINY_SPI_STATUS)&
> + TINY_SPI_STATUS_TXE))
> + cpu_relax();
> + }
> + return t->len;
> +}
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