From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jagan Teki Date: Sun, 02 Jun 2013 23:50:21 +0530 Subject: [U-Boot] [U-Boot, 2/2, V5] spi: exynos: Support SPI_PREAMBLE mode In-Reply-To: <1369807838-18683-3-git-send-email-rajeshwari.s@samsung.com> References: <1369807838-18683-3-git-send-email-rajeshwari.s@samsung.com> Message-ID: <51AB8CE5.3010606@gmail.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 29-05-2013 01:40, Rajeshwari Shinde wrote: > 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 > Signed-off-by: Rajeshwari Shinde > > --- > 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. > Changes in V5: > - In commit message header changed EXYNOS: SPI: to spi:exynos. > 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, ®s->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, ®s->tx_data); > out_bytes--; > } > - if (rx_lvl > 0 && in_bytes) { > + if (rx_lvl > 0) { > temp = readl(®s->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; > } > > /** Reviewed-by: Jagannadha Sutradharudu Teki -- Thanks, Jagan.