spi: tegra114: flush fifos

Fixes: Flush TX and RX FIFOs before start of new transfer and on FIFO
overflow or underrun errors.

Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-tegra114.c b/drivers/spi/spi-tegra114.c
index a6153b905d1a5205bd2bd5fbab39c0c384ebd559..28aa080a94ff8c39a9baa7bdd4bac0790bf761bd 100644 (file)
--- a/drivers/spi/spi-tegra114.c
+++ b/drivers/spi/spi-tegra114.c
@@ -499,22 +499,37 @@ static int tegra_spi_start_rx_dma(struct tegra_spi_data *tspi, int len)
        return 0;
 }
 
-static int tegra_spi_start_dma_based_transfer(
-               struct tegra_spi_data *tspi, struct spi_transfer *t)
+static int tegra_spi_flush_fifos(struct tegra_spi_data *tspi)
 {
-       u32 val;
-       unsigned int len;
-       int ret = 0;
+       unsigned long timeout = jiffies + HZ;
        u32 status;
 
-       /* Make sure that Rx and Tx fifo are empty */
        status = tegra_spi_readl(tspi, SPI_FIFO_STATUS);
        if ((status & SPI_FIFO_EMPTY) != SPI_FIFO_EMPTY) {
-               dev_err(tspi->dev, "Rx/Tx fifo are not empty status 0x%08x\n",
-                       (unsigned)status);
-               return -EIO;
+               status |= SPI_RX_FIFO_FLUSH | SPI_TX_FIFO_FLUSH;
+               tegra_spi_writel(tspi, status, SPI_FIFO_STATUS);
+               while ((status & SPI_FIFO_EMPTY) != SPI_FIFO_EMPTY) {
+                       status = tegra_spi_readl(tspi, SPI_FIFO_STATUS);
+                       if (time_after(jiffies, timeout)) {
+                               dev_err(tspi->dev,
+                                       "timeout waiting for fifo flush\n");
+                               return -EIO;
+                       }
+
+                       udelay(1);
+               }
        }
 
+       return 0;
+}
+
+static int tegra_spi_start_dma_based_transfer(
+               struct tegra_spi_data *tspi, struct spi_transfer *t)
+{
+       u32 val;
+       unsigned int len;
+       int ret = 0;
+
        val = SPI_DMA_BLK_SET(tspi->curr_dma_words - 1);
        tegra_spi_writel(tspi, val, SPI_DMA_BLK);
 
@@ -779,6 +794,9 @@ static int tegra_spi_start_transfer_one(struct spi_device *spi,
        dev_dbg(tspi->dev, "The def 0x%x and written 0x%x\n",
                tspi->def_command1_reg, (unsigned)command1);
 
+       ret = tegra_spi_flush_fifos(tspi);
+       if (ret < 0)
+               return ret;
        if (total_fifo_words > SPI_FIFO_DEPTH)
                ret = tegra_spi_start_dma_based_transfer(tspi, t);
        else
@@ -876,6 +894,7 @@ static int tegra_spi_transfer_one_message(struct spi_master *master,
                            (tspi->cur_direction & DATA_DIR_RX))
                                dmaengine_terminate_all(tspi->rx_dma_chan);
                        ret = -EIO;
+                       tegra_spi_flush_fifos(tspi);
                        reset_control_assert(tspi->rst);
                        udelay(2);
                        reset_control_deassert(tspi->rst);
@@ -929,6 +948,7 @@ static irqreturn_t handle_cpu_based_xfer(struct tegra_spi_data *tspi)
                        tspi->status_reg);
                dev_err(tspi->dev, "CpuXfer 0x%08x:0x%08x\n",
                        tspi->command1_reg, tspi->dma_control_reg);
+               tegra_spi_flush_fifos(tspi);
                reset_control_assert(tspi->rst);
                udelay(2);
                reset_control_deassert(tspi->rst);
@@ -1001,6 +1021,7 @@ static irqreturn_t handle_dma_based_xfer(struct tegra_spi_data *tspi)
                        tspi->status_reg);
                dev_err(tspi->dev, "DmaXfer 0x%08x:0x%08x\n",
                        tspi->command1_reg, tspi->dma_control_reg);
+               tegra_spi_flush_fifos(tspi);
                reset_control_assert(tspi->rst);
                udelay(2);
                reset_control_deassert(tspi->rst);