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path: root/drivers/spi/spi-bcm2835.c
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Diffstat (limited to 'drivers/spi/spi-bcm2835.c')
-rw-r--r--drivers/spi/spi-bcm2835.c87
1 files changed, 50 insertions, 37 deletions
diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index 37875cf942f7..830d99c89b0b 100644
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -69,7 +69,7 @@
#define BCM2835_SPI_CS_CS_01 0x00000001
#define BCM2835_SPI_POLLING_LIMIT_US 30
-#define BCM2835_SPI_TIMEOUT_MS 30000
+#define BCM2835_SPI_POLLING_JIFFIES 2
#define BCM2835_SPI_MODE_BITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH \
| SPI_NO_CS | SPI_3WIRE)
@@ -157,42 +157,6 @@ static irqreturn_t bcm2835_spi_interrupt(int irq, void *dev_id)
return IRQ_HANDLED;
}
-static int bcm2835_spi_transfer_one_poll(struct spi_master *master,
- struct spi_device *spi,
- struct spi_transfer *tfr,
- u32 cs,
- unsigned long xfer_time_us)
-{
- struct bcm2835_spi *bs = spi_master_get_devdata(master);
- /* set timeout to 1 second of maximum polling */
- unsigned long timeout = jiffies + HZ;
-
- /* enable HW block without interrupts */
- bcm2835_wr(bs, BCM2835_SPI_CS, cs | BCM2835_SPI_CS_TA);
-
- /* loop until finished the transfer */
- while (bs->rx_len) {
- /* read from fifo as much as possible */
- bcm2835_rd_fifo(bs);
- /* fill in tx fifo as much as possible */
- bcm2835_wr_fifo(bs);
- /* if we still expect some data after the read,
- * check for a possible timeout
- */
- if (bs->rx_len && time_after(jiffies, timeout)) {
- /* Transfer complete - reset SPI HW */
- bcm2835_spi_reset_hw(master);
- /* and return timeout */
- return -ETIMEDOUT;
- }
- }
-
- /* Transfer complete - reset SPI HW */
- bcm2835_spi_reset_hw(master);
- /* and return without waiting for completion */
- return 0;
-}
-
static int bcm2835_spi_transfer_one_irq(struct spi_master *master,
struct spi_device *spi,
struct spi_transfer *tfr,
@@ -229,6 +193,55 @@ static int bcm2835_spi_transfer_one_irq(struct spi_master *master,
return 1;
}
+static int bcm2835_spi_transfer_one_poll(struct spi_master *master,
+ struct spi_device *spi,
+ struct spi_transfer *tfr,
+ u32 cs,
+ unsigned long xfer_time_us)
+{
+ struct bcm2835_spi *bs = spi_master_get_devdata(master);
+ unsigned long timeout;
+
+ /* enable HW block without interrupts */
+ bcm2835_wr(bs, BCM2835_SPI_CS, cs | BCM2835_SPI_CS_TA);
+
+ /* fill in the fifo before timeout calculations
+ * if we are interrupted here, then the data is
+ * getting transferred by the HW while we are interrupted
+ */
+ bcm2835_wr_fifo(bs);
+
+ /* set the timeout */
+ timeout = jiffies + BCM2835_SPI_POLLING_JIFFIES;
+
+ /* loop until finished the transfer */
+ while (bs->rx_len) {
+ /* fill in tx fifo with remaining data */
+ bcm2835_wr_fifo(bs);
+
+ /* read from fifo as much as possible */
+ bcm2835_rd_fifo(bs);
+
+ /* if there is still data pending to read
+ * then check the timeout
+ */
+ if (bs->rx_len && time_after(jiffies, timeout)) {
+ dev_dbg_ratelimited(&spi->dev,
+ "timeout period reached: jiffies: %lu remaining tx/rx: %d/%d - falling back to interrupt mode\n",
+ jiffies - timeout,
+ bs->tx_len, bs->rx_len);
+ /* fall back to interrupt mode */
+ return bcm2835_spi_transfer_one_irq(master, spi,
+ tfr, cs);
+ }
+ }
+
+ /* Transfer complete - reset SPI HW */
+ bcm2835_spi_reset_hw(master);
+ /* and return without waiting for completion */
+ return 0;
+}
+
static int bcm2835_spi_transfer_one(struct spi_master *master,
struct spi_device *spi,
struct spi_transfer *tfr)