@@ -7,6 +7,7 @@
#include <linux/bitfield.h>
#include <linux/bitops.h>
#include <linux/clk.h>
+#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/module.h>
@@ -16,6 +17,7 @@
#include <asm/unaligned.h>
#define SSI_TIMEOUT_MS 2000
+#define SSI_POLL_TIMEOUT_US 200
#define SSI_MAX_CLK_DIVIDER 254
#define SSI_MIN_CLK_DIVIDER 4
@@ -290,21 +292,23 @@ static void uniphier_spi_recv(struct uniphier_spi_priv *priv)
static void uniphier_spi_fill_tx_fifo(struct uniphier_spi_priv *priv)
{
- unsigned int tx_count;
+ unsigned int fifo_threshold, fill_bytes;
u32 val;
- tx_count = DIV_ROUND_UP(priv->tx_bytes,
+ fifo_threshold = DIV_ROUND_UP(priv->rx_bytes,
bytes_per_word(priv->bits_per_word));
- tx_count = min(tx_count, SSI_FIFO_DEPTH);
+ fifo_threshold = min(fifo_threshold, SSI_FIFO_DEPTH);
+
+ fill_bytes = fifo_threshold - (priv->rx_bytes - priv->tx_bytes);
/* set fifo threshold */
val = readl(priv->base + SSI_FC);
val &= ~(SSI_FC_TXFTH_MASK | SSI_FC_RXFTH_MASK);
- val |= FIELD_PREP(SSI_FC_TXFTH_MASK, tx_count);
- val |= FIELD_PREP(SSI_FC_RXFTH_MASK, tx_count);
+ val |= FIELD_PREP(SSI_FC_TXFTH_MASK, fifo_threshold);
+ val |= FIELD_PREP(SSI_FC_RXFTH_MASK, fifo_threshold);
writel(val, priv->base + SSI_FC);
- while (tx_count--)
+ while (fill_bytes--)
uniphier_spi_send(priv);
}
@@ -323,20 +327,14 @@ static void uniphier_spi_set_cs(struct spi_device *spi, bool enable)
writel(val, priv->base + SSI_FPS);
}
-static int uniphier_spi_transfer_one(struct spi_master *master,
- struct spi_device *spi,
- struct spi_transfer *t)
+static int uniphier_spi_transfer_one_irq(struct spi_master *master,
+ struct spi_device *spi,
+ struct spi_transfer *t)
{
struct uniphier_spi_priv *priv = spi_master_get_devdata(master);
struct device *dev = master->dev.parent;
unsigned long time_left;
- /* Terminate and return success for 0 byte length transfer */
- if (!t->len)
- return 0;
-
- uniphier_spi_setup_transfer(spi, t);
-
reinit_completion(&priv->xfer_done);
uniphier_spi_fill_tx_fifo(priv);
@@ -356,6 +354,59 @@ static int uniphier_spi_transfer_one(struct spi_master *master,
return priv->error;
}
+static int uniphier_spi_transfer_one_poll(struct spi_master *master,
+ struct spi_device *spi,
+ struct spi_transfer *t)
+{
+ struct uniphier_spi_priv *priv = spi_master_get_devdata(master);
+ int loop = SSI_POLL_TIMEOUT_US * 10;
+
+ while (priv->tx_bytes) {
+ uniphier_spi_fill_tx_fifo(priv);
+
+ while ((priv->rx_bytes - priv->tx_bytes) > 0) {
+ while (!(readl(priv->base + SSI_SR) & SSI_SR_RNE)
+ && loop--)
+ ndelay(100);
+
+ if (loop == -1)
+ goto irq_transfer;
+
+ uniphier_spi_recv(priv);
+ }
+ }
+
+ return 0;
+
+irq_transfer:
+ return uniphier_spi_transfer_one_irq(master, spi, t);
+}
+
+static int uniphier_spi_transfer_one(struct spi_master *master,
+ struct spi_device *spi,
+ struct spi_transfer *t)
+{
+ struct uniphier_spi_priv *priv = spi_master_get_devdata(master);
+ unsigned long threshold;
+
+ /* Terminate and return success for 0 byte length transfer */
+ if (!t->len)
+ return 0;
+
+ uniphier_spi_setup_transfer(spi, t);
+
+ /*
+ * If the transfer operation will take longer than
+ * SSI_POLL_TIMEOUT_US, it should use irq.
+ */
+ threshold = DIV_ROUND_UP(SSI_POLL_TIMEOUT_US * priv->speed_hz,
+ USEC_PER_SEC * BITS_PER_BYTE);
+ if (t->len > threshold)
+ return uniphier_spi_transfer_one_irq(master, spi, t);
+ else
+ return uniphier_spi_transfer_one_poll(master, spi, t);
+}
+
static int uniphier_spi_prepare_transfer_hardware(struct spi_master *master)
{
struct uniphier_spi_priv *priv = spi_master_get_devdata(master);
Introduce new polling mode for short size transfer. Either the estimated transfer time is estimated to exceed 200us, or polling loop actually exceeds 200us, it switches to irq mode. Signed-off-by: Keiji Hayashibara <hayashibara.keiji@socionext.com> --- drivers/spi/spi-uniphier.c | 81 +++++++++++++++++++++++++++++++++++++--------- 1 file changed, 66 insertions(+), 15 deletions(-)