diff options
| -rw-r--r-- | drivers/spi/spi-bcm2835.c | 87 |
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) |