From: Qipan Li <[email protected]> there are many SPI clients which use the following protocal: step 1: send command bytes to clients(rx buffer is empty) step 2: send data bytes to clients or receive data bytes from clients. SiRFprimaII provides a shortcut for this kind of SPI transfer. when tx buf is less or equal than 4 bytes and rx buf is null in a transfer, we think it as 'command' data and use hardware command register for the transfer. here we can save some CPU loading than doing both tx and rx for a normal transfer.
Signed-off-by: Qipan Li <[email protected]> Signed-off-by: Barry Song <[email protected]> --- drivers/spi/spi-sirf.c | 39 ++++++++++++++++++++++++++++++++++++++- 1 file changed, 38 insertions(+), 1 deletion(-) diff --git a/drivers/spi/spi-sirf.c b/drivers/spi/spi-sirf.c index e430689..c400ab7 100644 --- a/drivers/spi/spi-sirf.c +++ b/drivers/spi/spi-sirf.c @@ -132,6 +132,7 @@ #define IS_DMA_VALID(x) (x && ALIGNED(x->tx_buf) && ALIGNED(x->rx_buf) && \ ALIGNED(x->len) && (x->len < 2 * PAGE_SIZE)) +#define SIRFSOC_MAX_CMD_BYTES 4 struct sirfsoc_spi { struct spi_bitbang bitbang; struct completion rx_done; @@ -161,7 +162,7 @@ struct sirfsoc_spi { dma_addr_t dst_start; void *dummypage; int word_width; /* in bytes */ - + bool tx_by_cmd; int chipselect[0]; }; @@ -260,6 +261,11 @@ static irqreturn_t spi_sirfsoc_irq(int irq, void *dev_id) writel(spi_stat, sspi->base + SIRFSOC_SPI_INT_STATUS); + if (sspi->tx_by_cmd && (spi_stat & SIRFSOC_SPI_FRM_END)) { + complete(&sspi->tx_done); + writel(0x0, sspi->base + SIRFSOC_SPI_INT_EN); + return IRQ_HANDLED; + } /* Error Conditions */ if (spi_stat & SIRFSOC_SPI_RX_OFLOW || spi_stat & SIRFSOC_SPI_TX_UFLOW) { @@ -310,6 +316,32 @@ static int spi_sirfsoc_transfer(struct spi_device *spi, struct spi_transfer *t) writel(SIRFSOC_SPI_INT_MASK_ALL, sspi->base + SIRFSOC_SPI_INT_STATUS); + if (t && t->tx_buf && !t->rx_buf && (t->len <= SIRFSOC_MAX_CMD_BYTES)) { + const u32 *cmd_ptr; + u32 cmd; + sspi->tx_by_cmd = true; + cmd_ptr = sspi->tx; + cmd = *cmd_ptr; + if (sspi->word_width == 1 && !(spi->mode & SPI_LSB_FIRST)) + cmd = cpu_to_be32(cmd) >> + ((SIRFSOC_MAX_CMD_BYTES - t->len) * 8); + if (sspi->word_width == 2 && t->len == 4 && + (!(spi->mode & SPI_LSB_FIRST))) + cmd = ((cmd & 0xffff) << 16) | (cmd >> 16); + writel(cmd, sspi->base + SIRFSOC_SPI_CMD); + + writel(SIRFSOC_SPI_FRM_END_INT_EN, + sspi->base + SIRFSOC_SPI_INT_EN); + writel(SIRFSOC_SPI_CMD_TX_EN, + sspi->base + SIRFSOC_SPI_TX_RX_EN); + + if (wait_for_completion_timeout(&sspi->tx_done, timeout) == 0) { + dev_err(&spi->dev, "transfer timeout\n"); + return 0; + } + return t->len; + } else + sspi->tx_by_cmd = false; if (sspi->left_tx_word == 1) { writel(readl(sspi->base + SIRFSOC_SPI_CTRL) | SIRFSOC_SPI_ENA_AUTO_CLR, @@ -519,6 +551,11 @@ spi_sirfsoc_setup_transfer(struct spi_device *spi, struct spi_transfer *t) writel(txfifo_ctrl, sspi->base + SIRFSOC_SPI_TXFIFO_CTRL); writel(rxfifo_ctrl, sspi->base + SIRFSOC_SPI_RXFIFO_CTRL); + if (t && t->tx_buf && !t->rx_buf && (t->len <= SIRFSOC_MAX_CMD_BYTES)) + regval |= (SIRFSOC_SPI_CMD_BYTE_NUM((t->len - 1)) | + SIRFSOC_SPI_CMD_MODE); + else + regval &= ~SIRFSOC_SPI_CMD_MODE; writel(regval, sspi->base + SIRFSOC_SPI_CTRL); if (IS_DMA_VALID(t)) { -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
