diff options
| -rw-r--r-- | drivers/spi/dw_spi.c | 71 |
1 files changed, 48 insertions, 23 deletions
diff --git a/drivers/spi/dw_spi.c b/drivers/spi/dw_spi.c index d3aaf8db86c..7a2a72268f0 100644 --- a/drivers/spi/dw_spi.c +++ b/drivers/spi/dw_spi.c @@ -160,6 +160,37 @@ static inline void mrst_spi_debugfs_remove(struct dw_spi *dws) } #endif /* CONFIG_DEBUG_FS */ +/* Return the max entries we can fill into tx fifo */ +static inline u32 tx_max(struct dw_spi *dws) +{ + u32 tx_left, tx_room, rxtx_gap; + + tx_left = (dws->tx_end - dws->tx) / dws->n_bytes; + tx_room = dws->fifo_len - dw_readw(dws, txflr); + + /* + * Another concern is about the tx/rx mismatch, we + * though to use (dws->fifo_len - rxflr - txflr) as + * one maximum value for tx, but it doesn't cover the + * data which is out of tx/rx fifo and inside the + * shift registers. So a control from sw point of + * view is taken. + */ + rxtx_gap = ((dws->rx_end - dws->rx) - (dws->tx_end - dws->tx)) + / dws->n_bytes; + + return min3(tx_left, tx_room, (u32) (dws->fifo_len - rxtx_gap)); +} + +/* Return the max entries we should read out of rx fifo */ +static inline u32 rx_max(struct dw_spi *dws) +{ + u32 rx_left = (dws->rx_end - dws->rx) / dws->n_bytes; + + return min(rx_left, (u32)dw_readw(dws, rxflr)); +} + + static void wait_till_not_busy(struct dw_spi *dws) { unsigned long end = jiffies + 1 + usecs_to_jiffies(5000); @@ -175,33 +206,30 @@ static void wait_till_not_busy(struct dw_spi *dws) static int dw_writer(struct dw_spi *dws) { + u32 max = tx_max(dws); u16 txw = 0; - if (!(dw_readw(dws, sr) & SR_TF_NOT_FULL) - || (dws->tx == dws->tx_end)) - return 0; - - /* Set the tx word if the transfer's original "tx" is not null */ - if (dws->tx_end - dws->len) { - if (dws->n_bytes == 1) - txw = *(u8 *)(dws->tx); - else - txw = *(u16 *)(dws->tx); + while (max--) { + /* Set the tx word if the transfer's original "tx" is not null */ + if (dws->tx_end - dws->len) { + if (dws->n_bytes == 1) + txw = *(u8 *)(dws->tx); + else + txw = *(u16 *)(dws->tx); + } + dw_writew(dws, dr, txw); + dws->tx += dws->n_bytes; } - dw_writew(dws, dr, txw); - dws->tx += dws->n_bytes; - - wait_till_not_busy(dws); return 1; } static int dw_reader(struct dw_spi *dws) { + u32 max = rx_max(dws); u16 rxw; - while ((dw_readw(dws, sr) & SR_RF_NOT_EMPT) - && (dws->rx < dws->rx_end)) { + while (max--) { rxw = dw_readw(dws, dr); /* Care rx only if the transfer's original "rx" is not null */ if (dws->rx_end - dws->len) { @@ -213,7 +241,6 @@ static int dw_reader(struct dw_spi *dws) dws->rx += dws->n_bytes; } - wait_till_not_busy(dws); return dws->rx == dws->rx_end; } @@ -368,13 +395,11 @@ static irqreturn_t dw_spi_irq(int irq, void *dev_id) /* Must be called inside pump_transfers() */ static void poll_transfer(struct dw_spi *dws) { - while (dw_writer(dws)) + do { + dw_writer(dws); dw_reader(dws); - /* - * There is a possibility that the last word of a transaction - * will be lost if data is not ready. Re-read to solve this issue. - */ - dw_reader(dws); + cpu_relax(); + } while (dws->rx_end > dws->rx); dw_spi_xfer_done(dws); } |