Support interfaces with a preamble before each received message.

We handle this when the client has requested a SPI_XFER_END, meaning that we must close of the transaction. In this case we read until we see the preamble (or a timeout occurs), skipping all data before and including the preamble. The client will receive only data bytes after the preamble.

Signed-off-by: Simon Glass sjg@chromium.org Signed-off-by: Rajeshwari Shinde rajeshwari.s@samsung.com --- Changes in V2: - Remove preamable_count variable which is not really needed - Fix checkpatch warning (multiple assignments) Changes in V3: - Modified the if logic in spi_rx_tx function - Added blank lines as suggested by Minkyu Kang. - Removed in_bytes check in while loop. - Added a error check. Changes in V4: - Corrected a if condition. drivers/spi/exynos_spi.c | 69 +++++++++++++++++++++++++++++++++++++++------ 1 files changed, 59 insertions(+), 10 deletions(-)

diff --git a/drivers/spi/exynos_spi.c b/drivers/spi/exynos_spi.c index 607e1cd..01378d0 100644 --- a/drivers/spi/exynos_spi.c +++ b/drivers/spi/exynos_spi.c @@ -51,6 +51,7 @@ struct exynos_spi_slave { unsigned int mode; enum periph_id periph_id; /* Peripheral ID for this device */ unsigned int fifo_size; + int skip_preamble; };

static struct spi_bus *spi_get_bus(unsigned dev_index) @@ -105,6 +106,8 @@ struct spi_slave *spi_setup_slave(unsigned int busnum, unsigned int cs, else spi_slave->fifo_size = 256;

+ spi_slave->skip_preamble = 0; + spi_slave->freq = bus->frequency; if (max_hz) spi_slave->freq = min(max_hz, spi_slave->freq); @@ -217,17 +220,23 @@ static void spi_request_bytes(struct exynos_spi *regs, int count) writel(count | SPI_PACKET_CNT_EN, &regs->pkt_cnt); }

-static void spi_rx_tx(struct exynos_spi_slave *spi_slave, int todo, - void **dinp, void const **doutp) +static int spi_rx_tx(struct exynos_spi_slave *spi_slave, int todo, + void **dinp, void const **doutp, unsigned long flags) { struct exynos_spi *regs = spi_slave->regs; uchar *rxp = *dinp; const uchar *txp = *doutp; int rx_lvl, tx_lvl; uint out_bytes, in_bytes; + int toread; + unsigned start = get_timer(0); + int stopping;

out_bytes = in_bytes = todo;

+ stopping = spi_slave->skip_preamble && (flags & SPI_XFER_END) && + !(spi_slave->mode & SPI_SLAVE); + /* * If there's something to send, do a software reset and set a * transaction size. @@ -238,6 +247,8 @@ static void spi_rx_tx(struct exynos_spi_slave *spi_slave, int todo, * Bytes are transmitted/received in pairs. Wait to receive all the * data because then transmission will be done as well. */ + toread = in_bytes; + while (in_bytes) { int temp;

@@ -248,15 +259,43 @@ static void spi_rx_tx(struct exynos_spi_slave *spi_slave, int todo, writel(temp, &regs->tx_data); out_bytes--; } - if (rx_lvl > 0 && in_bytes) { + if (rx_lvl > 0) { temp = readl(&regs->rx_data); - if (rxp) - *rxp++ = temp; - in_bytes--; + if (spi_slave->skip_preamble) { + if (temp == SPI_PREAMBLE_END_BYTE) { + spi_slave->skip_preamble = 0; + stopping = 0; + } + } else { + if (rxp || stopping) + *rxp++ = temp; + in_bytes--; + } + toread--; + } else if (!toread) { + /* + * We have run out of input data, but haven't read + * enough bytes after the preamble yet. Read some more, + * and make sure that we transmit dummy bytes too, to + * keep things going. + */ + assert(!out_bytes); + out_bytes = in_bytes; + toread = in_bytes; + txp = NULL; + spi_request_bytes(regs, toread); + } + if (spi_slave->skip_preamble && get_timer(start) > 100) { + printf("SPI timeout: in_bytes=%d, out_bytes=%d, ", + in_bytes, out_bytes); + return -1; } } + *dinp = rxp; *doutp = txp; + + return 0; }

/** @@ -276,6 +315,7 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout, struct exynos_spi_slave *spi_slave = to_exynos_spi(slave); int upto, todo; int bytelen; + int ret = 0;

/* spi core configured to do 8 bit transfers */ if (bitlen % 8) { @@ -289,16 +329,24 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,

/* Exynos SPI limits each transfer to 65535 bytes */ bytelen = bitlen / 8; - for (upto = 0; upto < bytelen; upto += todo) { + for (upto = 0; !ret && upto < bytelen; upto += todo) { todo = min(bytelen - upto, (1 << 16) - 1); - spi_rx_tx(spi_slave, todo, &din, &dout); + ret = spi_rx_tx(spi_slave, todo, &din, &dout, flags); + if (ret) + break; }

/* Stop the transaction, if necessary. */ - if ((flags & SPI_XFER_END)) + if ((flags & SPI_XFER_END) && !(spi_slave->mode & SPI_SLAVE)) { spi_cs_deactivate(slave); + if (spi_slave->skip_preamble) { + assert(!spi_slave->skip_preamble); + debug("Failed to complete premable transaction\n"); + ret = -1; + } + }

- return 0; + return ret; }

/** @@ -325,6 +373,7 @@ void spi_cs_activate(struct spi_slave *slave)

clrbits_le32(&spi_slave->regs->cs_reg, SPI_SLAVE_SIG_INACT); debug("Activate CS, bus %d\n", spi_slave->slave.bus); + spi_slave->skip_preamble = spi_slave->mode & SPI_PREAMBLE; }

/**