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authorQipan Li <Qipan.Li@csr.com>2014-03-01 12:38:17 +0800
committerMark Brown <broonie@linaro.org>2014-03-03 11:22:20 +0800
commiteeb7139524d1851c29b5c02b3dcd6679299a104e (patch)
tree330b91bd194e8024559ad597b0a1c905f53168db /drivers/spi/spi-sirf.c
parent71aa2e3207ad3249b4a7ceff7ca775a08341fdcb (diff)
downloadlinux-eeb7139524d1851c29b5c02b3dcd6679299a104e.tar.bz2
spi: sirf: provide a shortcut for spi command-data mode
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 <Qipan.Li@csr.com> Signed-off-by: Barry Song <Baohua.Song@csr.com> Signed-off-by: Mark Brown <broonie@linaro.org>
Diffstat (limited to 'drivers/spi/spi-sirf.c')
-rw-r--r--drivers/spi/spi-sirf.c50
1 files changed, 50 insertions, 0 deletions
diff --git a/drivers/spi/spi-sirf.c b/drivers/spi/spi-sirf.c
index dc962a17f373..a72b8f87a156 100644
--- a/drivers/spi/spi-sirf.c
+++ b/drivers/spi/spi-sirf.c
@@ -131,6 +131,8 @@
#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;
@@ -161,6 +163,12 @@ struct sirfsoc_spi {
void *dummypage;
int word_width; /* in bytes */
+ /*
+ * if tx size is not more than 4 and rx size is NULL, use
+ * command model
+ */
+ bool tx_by_cmd;
+
int chipselect[0];
};
@@ -259,6 +267,12 @@ 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) {
@@ -309,6 +323,34 @@ 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);
+ /*
+ * fill tx_buf into command register and wait for its completion
+ */
+ if (sspi->tx_by_cmd) {
+ u32 cmd;
+ memcpy(&cmd, sspi->tx, t->len);
+
+ 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;
+ }
+
if (sspi->left_tx_word == 1) {
writel(readl(sspi->base + SIRFSOC_SPI_CTRL) |
SIRFSOC_SPI_ENA_AUTO_CLR,
@@ -509,6 +551,14 @@ 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);
+ sspi->tx_by_cmd = true;
+ } else {
+ regval &= ~SIRFSOC_SPI_CMD_MODE;
+ sspi->tx_by_cmd = false;
+ }
writel(regval, sspi->base + SIRFSOC_SPI_CTRL);
if (IS_DMA_VALID(t)) {