spi/xilinx: Support cores with no interrupt

The core can run in polling mode. In fact, the performance of the core
is similar (or even better), due to the fact most of the spi
transactions are just a couple of bytes and there is one irq per
transactions.

When an mtd device is connected via spi, reading 8MB of data produces
more than 80K interrupts (with irq disabling, context swith....)

Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-xilinx.c b/drivers/spi/spi-xilinx.c
index 12b311ed9bfaab9e1a8ab3083d3bab82c2c34772..f21e857d54b1a969b6c8a9bd0004e3558dd37d1c 100644 (file)
--- a/drivers/spi/spi-xilinx.c
+++ b/drivers/spi/spi-xilinx.c
@@ -173,8 +173,11 @@ static void xspi_init_hw(struct xilinx_spi *xspi)
        xspi->write_fn(XSPI_INTR_TX_EMPTY,
                        regs_base + XIPIF_V123B_IIER_OFFSET);
        /* Enable the global IPIF interrupt */
-       xspi->write_fn(XIPIF_V123B_GINTR_ENABLE,
-               regs_base + XIPIF_V123B_DGIER_OFFSET);
+       if (xspi->irq >= 0)
+               xspi->write_fn(XIPIF_V123B_GINTR_ENABLE,
+                       regs_base + XIPIF_V123B_DGIER_OFFSET);
+       else
+               xspi->write_fn(0, regs_base + XIPIF_V123B_DGIER_OFFSET);
        /* Deselect the slave on the SPI bus */
        xspi->write_fn(0xffff, regs_base + XSPI_SSR_OFFSET);
        /* Disable the transmitter, enable Manual Slave Select Assertion,
@@ -264,7 +267,12 @@ static int xilinx_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
                                                        ~XSPI_CR_TRANS_INHIBIT;
                xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET);
 
-               wait_for_completion(&xspi->done);
+               if (xspi->irq >= 0)
+                       wait_for_completion(&xspi->done);
+               else
+                       while (!(xspi->read_fn(xspi->regs + XSPI_SR_OFFSET) &
+                                               XSPI_SR_TX_EMPTY_MASK))
+                               ;
 
                /* A transmit has just completed. Process received data and
                 * check for more data to transmit. Always inhibit the
@@ -419,20 +427,17 @@ static int xilinx_spi_probe(struct platform_device *pdev)
 
        xspi->buffer_size = xilinx_spi_find_buffer_size(xspi);
 
-       /* SPI controller initializations */
-       xspi_init_hw(xspi);
-
        xspi->irq = platform_get_irq(pdev, 0);
-       if (xspi->irq < 0) {
-               ret = xspi->irq;
-               goto put_master;
+       if (xspi->irq >= 0) {
+               /* Register for SPI Interrupt */
+               ret = devm_request_irq(&pdev->dev, xspi->irq, xilinx_spi_irq, 0,
+                               dev_name(&pdev->dev), xspi);
+               if (ret)
+                       goto put_master;
        }
 
-       /* Register for SPI Interrupt */
-       ret = devm_request_irq(&pdev->dev, xspi->irq, xilinx_spi_irq, 0,
-                              dev_name(&pdev->dev), xspi);
-       if (ret)
-               goto put_master;
+       /* SPI controller initializations */
+       xspi_init_hw(xspi);
 
        ret = spi_bitbang_start(&xspi->bitbang);
        if (ret) {