spi/dw_spi: improve the interrupt mode with the batch ops

leverage the performance gain by change in low level
read/write batch operations

Signed-off-by: Alek Du <alek.du@intel.com>
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

1 files changed, 16 insertions, 47 deletions

diff --git a/drivers/spi/dw_spi.c b/drivers/spi/dw_spi.c
index 7a2a72268f0a..855ac4ae0f22 100644
--- a/drivers/spi/dw_spi.c
+++ b/drivers/spi/dw_spi.c
@@ -190,21 +190,7 @@ static inline u32 rx_max(struct dw_spi *dws)
         return min(rx_left, (u32)dw_readw(dws, rxflr));
 }
 
-
-static void wait_till_not_busy(struct dw_spi *dws)
-{
-        unsigned long end = jiffies + 1 + usecs_to_jiffies(5000);
-
-        while (time_before(jiffies, end)) {
-                if (!(dw_readw(dws, sr) & SR_BUSY))
-                        return;
-                cpu_relax();
-        }
-        dev_err(&dws->master->dev,
-                "DW SPI: Status keeps busy for 5000us after a read/write!\n");
-}
-
-static int dw_writer(struct dw_spi *dws)
+static void dw_writer(struct dw_spi *dws)
 {
         u32 max = tx_max(dws);
         u16 txw = 0;
@@ -220,11 +206,9 @@ static int dw_writer(struct dw_spi *dws)
                 dw_writew(dws, dr, txw);
                 dws->tx += dws->n_bytes;
         }
-
-        return 1;
 }
 
-static int dw_reader(struct dw_spi *dws)
+static void dw_reader(struct dw_spi *dws)
 {
         u32 max = rx_max(dws);
         u16 rxw;
@@ -240,8 +224,6 @@ static int dw_reader(struct dw_spi *dws)
                 }
                 dws->rx += dws->n_bytes;
         }
-
-        return dws->rx == dws->rx_end;
 }
 
 static void *next_transfer(struct dw_spi *dws)
@@ -340,35 +322,28 @@ EXPORT_SYMBOL_GPL(dw_spi_xfer_done);
 
 static irqreturn_t interrupt_transfer(struct dw_spi *dws)
 {
-        u16 irq_status, irq_mask = 0x3f;
-        u32 int_level = dws->fifo_len / 2;
-        u32 left;
+        u16 irq_status = dw_readw(dws, isr);
 
-        irq_status = dw_readw(dws, isr) & irq_mask;
         /* Error handling */
         if (irq_status & (SPI_INT_TXOI | SPI_INT_RXOI | SPI_INT_RXUI)) {
                 dw_readw(dws, txoicr);
                 dw_readw(dws, rxoicr);
                 dw_readw(dws, rxuicr);
-                int_error_stop(dws, "interrupt_transfer: fifo overrun");
+                int_error_stop(dws, "interrupt_transfer: fifo overrun/underrun");
                 return IRQ_HANDLED;
         }
 
+        dw_reader(dws);
+        if (dws->rx_end == dws->rx) {
+                spi_mask_intr(dws, SPI_INT_TXEI);
+                dw_spi_xfer_done(dws);
+                return IRQ_HANDLED;
+        }
         if (irq_status & SPI_INT_TXEI) {
                 spi_mask_intr(dws, SPI_INT_TXEI);
-
-                left = (dws->tx_end - dws->tx) / dws->n_bytes;
-                left = (left > int_level) ? int_level : left;
-
-                while (left--)
-                        dw_writer(dws);
-                dw_reader(dws);
-
-                /* Re-enable the IRQ if there is still data left to tx */
-                if (dws->tx_end > dws->tx)
-                        spi_umask_intr(dws, SPI_INT_TXEI);
-                else
-                        dw_spi_xfer_done(dws);
+                dw_writer(dws);
+                /* Enable TX irq always, it will be disabled when RX finished */
+                spi_umask_intr(dws, SPI_INT_TXEI);
         }
 
         return IRQ_HANDLED;
@@ -377,15 +352,13 @@ static irqreturn_t interrupt_transfer(struct dw_spi *dws)
 static irqreturn_t dw_spi_irq(int irq, void *dev_id)
 {
         struct dw_spi *dws = dev_id;
-        u16 irq_status, irq_mask = 0x3f;
+        u16 irq_status = dw_readw(dws, isr) & 0x3f;
 
-        irq_status = dw_readw(dws, isr) & irq_mask;
         if (!irq_status)
                 return IRQ_NONE;
 
         if (!dws->cur_msg) {
                 spi_mask_intr(dws, SPI_INT_TXEI);
-                /* Never fail */
                 return IRQ_HANDLED;
         }
 
@@ -492,12 +465,8 @@ static void pump_transfers(unsigned long data)
 
                 switch (bits) {
                 case 8:
-                        dws->n_bytes = 1;
-                        dws->dma_width = 1;
-                        break;
                 case 16:
-                        dws->n_bytes = 2;
-                        dws->dma_width = 2;
+                        dws->n_bytes = dws->dma_width = bits >> 3;
                         break;
                 default:
                         printk(KERN_ERR "MRST SPI0: unsupported bits:"
@@ -541,7 +510,7 @@ static void pump_transfers(unsigned long data)
                 txint_level = dws->fifo_len / 2;
                 txint_level = (templen > txint_level) ? txint_level : templen;
 
-                imask |= SPI_INT_TXEI;
+                imask |= SPI_INT_TXEI | SPI_INT_TXOI | SPI_INT_RXUI | SPI_INT_RXOI;
                 dws->transfer_handler = interrupt_transfer;
         }