diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/spi/spi-bcm2835aux.c | 43 |
1 files changed, 31 insertions, 12 deletions
diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c index f92b4a69fffa..05d2d6eb7bfa 100644 --- a/drivers/spi/spi-bcm2835aux.c +++ b/drivers/spi/spi-bcm2835aux.c @@ -104,6 +104,7 @@ struct bcm2835aux_spi { u8 *rx_buf; int tx_len; int rx_len; + int pending; }; static inline u32 bcm2835aux_rd(struct bcm2835aux_spi *bs, unsigned reg) @@ -120,15 +121,27 @@ static inline void bcm2835aux_wr(struct bcm2835aux_spi *bs, unsigned reg, static inline void bcm2835aux_rd_fifo(struct bcm2835aux_spi *bs) { u32 data; - int i; int count = min(bs->rx_len, 3); data = bcm2835aux_rd(bs, BCM2835_AUX_SPI_IO); if (bs->rx_buf) { - for (i = 0; i < count; i++) - *bs->rx_buf++ = (data >> (8 * (2 - i))) & 0xff; + switch (count) { + case 4: + *bs->rx_buf++ = (data >> 24) & 0xff; + /* fallthrough */ + case 3: + *bs->rx_buf++ = (data >> 16) & 0xff; + /* fallthrough */ + case 2: + *bs->rx_buf++ = (data >> 8) & 0xff; + /* fallthrough */ + case 1: + *bs->rx_buf++ = (data >> 0) & 0xff; + /* fallthrough - no default */ + } } bs->rx_len -= count; + bs->pending -= count; } static inline void bcm2835aux_wr_fifo(struct bcm2835aux_spi *bs) @@ -151,6 +164,7 @@ static inline void bcm2835aux_wr_fifo(struct bcm2835aux_spi *bs) /* and decrement length */ bs->tx_len -= count; + bs->pending += count; /* write to the correct TX-register */ if (bs->tx_len) @@ -183,6 +197,7 @@ static irqreturn_t bcm2835aux_spi_interrupt(int irq, void *dev_id) /* check if we have data to write */ while (bs->tx_len && + (bs->pending < 12) && (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT) & BCM2835_AUX_SPI_STAT_TX_FULL))) { bcm2835aux_wr_fifo(bs); @@ -234,6 +249,7 @@ static int bcm2835aux_spi_transfer_one_irq(struct spi_master *master, /* fill in tx fifo with data before enabling interrupts */ while ((bs->tx_len) && + (bs->pending < 12) && (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT) & BCM2835_AUX_SPI_STAT_TX_FULL))) { bcm2835aux_wr_fifo(bs); @@ -245,8 +261,7 @@ static int bcm2835aux_spi_transfer_one_irq(struct spi_master *master, static int bcm2835aux_spi_transfer_one_poll(struct spi_master *master, struct spi_device *spi, - struct spi_transfer *tfr, - unsigned long xfer_time_us) + struct spi_transfer *tfr) { struct bcm2835aux_spi *bs = spi_master_get_devdata(master); unsigned long timeout; @@ -305,7 +320,8 @@ static int bcm2835aux_spi_transfer_one(struct spi_master *master, { struct bcm2835aux_spi *bs = spi_master_get_devdata(master); unsigned long spi_hz, clk_hz, speed; - unsigned long spi_used_hz, xfer_time_us; + unsigned long spi_used_hz; + unsigned long long xfer_time_us; /* calculate the registers to handle * @@ -348,16 +364,19 @@ static int bcm2835aux_spi_transfer_one(struct spi_master *master, bs->rx_buf = tfr->rx_buf; bs->tx_len = tfr->len; bs->rx_len = tfr->len; + bs->pending = 0; - /* calculate the estimated time in us the transfer runs */ - xfer_time_us = tfr->len - * 9 /* clocks/byte - SPI-HW waits 1 clock after each byte */ - * 1000000 / spi_used_hz; + /* calculate the estimated time in us the transfer runs + * note that there are are 2 idle clocks after each + * chunk getting transferred - in our case the chunk size + * is 3 bytes, so we approximate this by 9 bits/byte + */ + xfer_time_us = tfr->len * 9 * 1000000; + do_div(xfer_time_us, spi_used_hz); /* run in polling mode for short transfers */ if (xfer_time_us < BCM2835_AUX_SPI_POLLING_LIMIT_US) - return bcm2835aux_spi_transfer_one_poll(master, spi, tfr, - xfer_time_us); + return bcm2835aux_spi_transfer_one_poll(master, spi, tfr); /* run in interrupt mode for all others */ return bcm2835aux_spi_transfer_one_irq(master, spi, tfr); |
