If we're sending bytes over SPI, we know the FIFO is empty at the
start of the transfer. There's no reason to wait for the interrupt
telling us to start--we can just start right away. Then if we
transmit everything in one swell foop we don't even need to bother
listening for TX interrupts.
In a test of "flashrom -p ec -r /tmp/foo.bin" interrupts were reduced
from ~30560 to ~29730, about a 3% savings.
This patch looks bigger than it is because I moved a few functions
rather than adding a forward declaration. The only actual change to
geni_spi_handle_tx() was to make it return a bool indicating if there
is more to tx.
Signed-off-by: Douglas Anderson <diand...@chromium.org>
---
drivers/spi/spi-geni-qcom.c | 167 +++++++++++++++++++-----------------
1 file changed, 86 insertions(+), 81 deletions(-)
diff --git a/drivers/spi/spi-geni-qcom.c b/drivers/spi/spi-geni-qcom.c
index 0dc3f4c55b0b..49c9eb870755 100644
--- a/drivers/spi/spi-geni-qcom.c
+++ b/drivers/spi/spi-geni-qcom.c
@@ -326,6 +326,88 @@ static int spi_geni_init(struct spi_geni_master *mas)
return 0;
}
+static unsigned int geni_byte_per_fifo_word(struct spi_geni_master *mas)
+{
+ /*
+ * Calculate how many bytes we'll put in each FIFO word. If the
+ * transfer words don't pack cleanly into a FIFO word we'll just put
+ * one transfer word in each FIFO word. If they do pack we'll pack 'em.
+ */
+ if (mas->fifo_width_bits % mas->cur_bits_per_word)
+ return roundup_pow_of_two(DIV_ROUND_UP(mas->cur_bits_per_word,
+ BITS_PER_BYTE));
+
+ return mas->fifo_width_bits / BITS_PER_BYTE;
+}
+
+static bool geni_spi_handle_tx(struct spi_geni_master *mas)
+{
+ struct geni_se *se = &mas->se;
+ unsigned int max_bytes;
+ const u8 *tx_buf;
+ unsigned int bytes_per_fifo_word = geni_byte_per_fifo_word(mas);
+ unsigned int i = 0;
+
+ max_bytes = (mas->tx_fifo_depth - mas->tx_wm) * bytes_per_fifo_word;
+ if (mas->tx_rem_bytes < max_bytes)
+ max_bytes = mas->tx_rem_bytes;
+
+ tx_buf = mas->cur_xfer->tx_buf + mas->cur_xfer->len - mas->tx_rem_bytes;
+ while (i < max_bytes) {
+ unsigned int j;
+ unsigned int bytes_to_write;
+ u32 fifo_word = 0;
+ u8 *fifo_byte = (u8 *)&fifo_word;
+
+ bytes_to_write = min(bytes_per_fifo_word, max_bytes - i);
+ for (j = 0; j < bytes_to_write; j++)
+ fifo_byte[j] = tx_buf[i++];
+ iowrite32_rep(se->base + SE_GENI_TX_FIFOn, &fifo_word, 1);
+ }
+ mas->tx_rem_bytes -= max_bytes;
+ if (!mas->tx_rem_bytes) {
+ writel(0, se->base + SE_GENI_TX_WATERMARK_REG);
+ return false;
+ }
+ return true;
+}
+
+static void geni_spi_handle_rx(struct spi_geni_master *mas)
+{
+ struct geni_se *se = &mas->se;
+ u32 rx_fifo_status;
+ unsigned int rx_bytes;
+ unsigned int rx_last_byte_valid;
+ u8 *rx_buf;
+ unsigned int bytes_per_fifo_word = geni_byte_per_fifo_word(mas);
+ unsigned int i = 0;
+
+ rx_fifo_status = readl(se->base + SE_GENI_RX_FIFO_STATUS);
+ rx_bytes = (rx_fifo_status & RX_FIFO_WC_MSK) * bytes_per_fifo_word;
+ if (rx_fifo_status & RX_LAST) {
+ rx_last_byte_valid = rx_fifo_status & RX_LAST_BYTE_VALID_MSK;
+ rx_last_byte_valid >>= RX_LAST_BYTE_VALID_SHFT;
+ if (rx_last_byte_valid && rx_last_byte_valid < 4)
+ rx_bytes -= bytes_per_fifo_word - rx_last_byte_valid;
+ }
+ if (mas->rx_rem_bytes < rx_bytes)
+ rx_bytes = mas->rx_rem_bytes;
+
+ rx_buf = mas->cur_xfer->rx_buf + mas->cur_xfer->len - mas->rx_rem_bytes;
+ while (i < rx_bytes) {
+ u32 fifo_word = 0;
+ u8 *fifo_byte = (u8 *)&fifo_word;
+ unsigned int bytes_to_read;
+ unsigned int j;
+
+ bytes_to_read = min(bytes_per_fifo_word, rx_bytes - i);
+ ioread32_rep(se->base + SE_GENI_RX_FIFOn, &fifo_word, 1);
+ for (j = 0; j < bytes_to_read; j++)
+ rx_buf[i++] = fifo_byte[j];
+ }
+ mas->rx_rem_bytes -= rx_bytes;
+}
+
static void setup_fifo_xfer(struct spi_transfer *xfer,
struct spi_geni_master *mas,
u16 mode, struct spi_master *spi)
@@ -398,8 +480,10 @@ static void setup_fifo_xfer(struct spi_transfer *xfer,
* setting up GENI SE engine, as driver starts data transfer
* for the watermark interrupt.
*/
- if (m_cmd & SPI_TX_ONLY)
- writel(mas->tx_wm, se->base + SE_GENI_TX_WATERMARK_REG);
+ if (m_cmd & SPI_TX_ONLY) {
+ if (geni_spi_handle_tx(mas))
+ writel(mas->tx_wm, se->base + SE_GENI_TX_WATERMARK_REG);
+ }
spin_unlock_irq(&mas->lock);
}
@@ -417,85 +501,6 @@ static int spi_geni_transfer_one(struct spi_master *spi,
return 1;
}
-static unsigned int geni_byte_per_fifo_word(struct spi_geni_master *mas)
-{
- /*
- * Calculate how many bytes we'll put in each FIFO word. If the
- * transfer words don't pack cleanly into a FIFO word we'll just put
- * one transfer word in each FIFO word. If they do pack we'll pack 'em.
- */
- if (mas->fifo_width_bits % mas->cur_bits_per_word)
- return roundup_pow_of_two(DIV_ROUND_UP(mas->cur_bits_per_word,
- BITS_PER_BYTE));
-
- return mas->fifo_width_bits / BITS_PER_BYTE;
-}
-
-static void geni_spi_handle_tx(struct spi_geni_master *mas)
-{
- struct geni_se *se = &mas->se;
- unsigned int max_bytes;
- const u8 *tx_buf;
- unsigned int bytes_per_fifo_word = geni_byte_per_fifo_word(mas);
- unsigned int i = 0;
-
- max_bytes = (mas->tx_fifo_depth - mas->tx_wm) * bytes_per_fifo_word;
- if (mas->tx_rem_bytes < max_bytes)
- max_bytes = mas->tx_rem_bytes;
-
- tx_buf = mas->cur_xfer->tx_buf + mas->cur_xfer->len - mas->tx_rem_bytes;
- while (i < max_bytes) {
- unsigned int j;
- unsigned int bytes_to_write;
- u32 fifo_word = 0;
- u8 *fifo_byte = (u8 *)&fifo_word;
-
- bytes_to_write = min(bytes_per_fifo_word, max_bytes - i);
- for (j = 0; j < bytes_to_write; j++)
- fifo_byte[j] = tx_buf[i++];
- iowrite32_rep(se->base + SE_GENI_TX_FIFOn, &fifo_word, 1);
- }
- mas->tx_rem_bytes -= max_bytes;
- if (!mas->tx_rem_bytes)
- writel(0, se->base + SE_GENI_TX_WATERMARK_REG);
-}
-
-static void geni_spi_handle_rx(struct spi_geni_master *mas)
-{
- struct geni_se *se = &mas->se;
- u32 rx_fifo_status;
- unsigned int rx_bytes;
- unsigned int rx_last_byte_valid;
- u8 *rx_buf;
- unsigned int bytes_per_fifo_word = geni_byte_per_fifo_word(mas);
- unsigned int i = 0;
-
- rx_fifo_status = readl(se->base + SE_GENI_RX_FIFO_STATUS);
- rx_bytes = (rx_fifo_status & RX_FIFO_WC_MSK) * bytes_per_fifo_word;
- if (rx_fifo_status & RX_LAST) {
- rx_last_byte_valid = rx_fifo_status & RX_LAST_BYTE_VALID_MSK;
- rx_last_byte_valid >>= RX_LAST_BYTE_VALID_SHFT;
- if (rx_last_byte_valid && rx_last_byte_valid < 4)
- rx_bytes -= bytes_per_fifo_word - rx_last_byte_valid;
- }
- if (mas->rx_rem_bytes < rx_bytes)
- rx_bytes = mas->rx_rem_bytes;
-
- rx_buf = mas->cur_xfer->rx_buf + mas->cur_xfer->len - mas->rx_rem_bytes;
- while (i < rx_bytes) {
- u32 fifo_word = 0;
- u8 *fifo_byte = (u8 *)&fifo_word;
- unsigned int bytes_to_read;
- unsigned int j;
-
- bytes_to_read = min(bytes_per_fifo_word, rx_bytes - i);
- ioread32_rep(se->base + SE_GENI_RX_FIFOn, &fifo_word, 1);
- for (j = 0; j < bytes_to_read; j++)
- rx_buf[i++] = fifo_byte[j];
- }
- mas->rx_rem_bytes -= rx_bytes;
-}
-
static irqreturn_t geni_spi_isr(int irq, void *data)
{
struct spi_master *spi = data;
--
2.28.0.618.gf4bc123cb7-goog
