diff options
Diffstat (limited to 'drivers/spi/exynos_spi.c')
| -rw-r--r-- | drivers/spi/exynos_spi.c | 76 |
1 files changed, 61 insertions, 15 deletions
diff --git a/drivers/spi/exynos_spi.c b/drivers/spi/exynos_spi.c index 7407d6c..699c57e 100644 --- a/drivers/spi/exynos_spi.c +++ b/drivers/spi/exynos_spi.c @@ -204,12 +204,29 @@ static void spi_get_fifo_levels(struct exynos_spi *regs, * * @param regs SPI peripheral registers * @param count Number of bytes to transfer + * @param step Number of bytes to transfer in each packet (1 or 4) */ -static void spi_request_bytes(struct exynos_spi *regs, int count) +static void spi_request_bytes(struct exynos_spi *regs, int count, int step) { + /* For word address we need to swap bytes */ + if (step == 4) { + setbits_le32(®s->mode_cfg, + SPI_MODE_CH_WIDTH_WORD | SPI_MODE_BUS_WIDTH_WORD); + count /= 4; + setbits_le32(®s->swap_cfg, SPI_TX_SWAP_EN | SPI_RX_SWAP_EN | + SPI_TX_BYTE_SWAP | SPI_RX_BYTE_SWAP | + SPI_TX_HWORD_SWAP | SPI_RX_HWORD_SWAP); + } else { + /* Select byte access and clear the swap configuration */ + clrbits_le32(®s->mode_cfg, + SPI_MODE_CH_WIDTH_WORD | SPI_MODE_BUS_WIDTH_WORD); + writel(0, ®s->swap_cfg); + } + assert(count && count < (1 << 16)); setbits_le32(®s->ch_cfg, SPI_CH_RST); clrbits_le32(®s->ch_cfg, SPI_CH_RST); + writel(count | SPI_PACKET_CNT_EN, ®s->pkt_cnt); } @@ -224,6 +241,7 @@ static int spi_rx_tx(struct exynos_spi_slave *spi_slave, int todo, int toread; unsigned start = get_timer(0); int stopping; + int step; out_bytes = in_bytes = todo; @@ -231,10 +249,19 @@ static int spi_rx_tx(struct exynos_spi_slave *spi_slave, int todo, !(spi_slave->mode & SPI_SLAVE); /* + * Try to transfer words if we can. This helps read performance at + * SPI clock speeds above about 20MHz. + */ + step = 1; + if (!((todo | (uintptr_t)rxp | (uintptr_t)txp) & 3) && + !spi_slave->skip_preamble) + step = 4; + + /* * If there's something to send, do a software reset and set a * transaction size. */ - spi_request_bytes(regs, todo); + spi_request_bytes(regs, todo, step); /* * Bytes are transmitted/received in pairs. Wait to receive all the @@ -247,14 +274,26 @@ static int spi_rx_tx(struct exynos_spi_slave *spi_slave, int todo, /* Keep the fifos full/empty. */ spi_get_fifo_levels(regs, &rx_lvl, &tx_lvl); + + /* + * Don't completely fill the txfifo, since we don't want our + * rxfifo to overflow, and it may already contain data. + */ while (tx_lvl < spi_slave->fifo_size/2 && out_bytes) { - temp = txp ? *txp++ : 0xff; + if (!txp) + temp = -1; + else if (step == 4) + temp = *(uint32_t *)txp; + else + temp = *txp; writel(temp, ®s->tx_data); - out_bytes--; - tx_lvl++; + out_bytes -= step; + if (txp) + txp += step; + tx_lvl += step; } - if (rx_lvl > 0) { - while (rx_lvl > 0) { + if (rx_lvl >= step) { + while (rx_lvl >= step) { temp = readl(®s->rx_data); if (spi_slave->skip_preamble) { if (temp == SPI_PREAMBLE_END_BYTE) { @@ -262,12 +301,15 @@ static int spi_rx_tx(struct exynos_spi_slave *spi_slave, int todo, stopping = 0; } } else { - if (rxp || stopping) - *rxp++ = temp; - in_bytes--; + if (rxp || stopping) { + *rxp = temp; + rxp += step; + } + in_bytes -= step; } - toread--; - rx_lvl--; + toread -= step; + rx_lvl -= step; + } } else if (!toread) { /* * We have run out of input data, but haven't read @@ -279,7 +321,7 @@ static int spi_rx_tx(struct exynos_spi_slave *spi_slave, int todo, out_bytes = in_bytes; toread = in_bytes; txp = NULL; - spi_request_bytes(regs, toread); + spi_request_bytes(regs, toread, step); } if (spi_slave->skip_preamble && get_timer(start) > 100) { printf("SPI timeout: in_bytes=%d, out_bytes=%d, ", @@ -323,10 +365,14 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout, if ((flags & SPI_XFER_BEGIN)) spi_cs_activate(slave); - /* Exynos SPI limits each transfer to 65535 bytes */ + /* + * Exynos SPI limits each transfer to 65535 transfers. To keep + * things simple, allow a maximum of 65532 bytes. We could allow + * more in word mode, but the performance difference is small. + */ bytelen = bitlen / 8; for (upto = 0; !ret && upto < bytelen; upto += todo) { - todo = min(bytelen - upto, (1 << 16) - 1); + todo = min(bytelen - upto, (1 << 16) - 4); ret = spi_rx_tx(spi_slave, todo, &din, &dout, flags); if (ret) break; |