From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Glass Date: Mon, 6 May 2013 06:06:24 -0600 Subject: [U-Boot] [PATCH 2/2] EXYNOS: SPI: Support SPI_PREAMBLE mode In-Reply-To: References: <1363933766-6555-1-git-send-email-rajeshwari.s@samsung.com> <1363933766-6555-3-git-send-email-rajeshwari.s@samsung.com> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Vadim, On Thu, May 2, 2013 at 7:28 PM, Vadim Bendebury wrote: > On Thu, Mar 21, 2013 at 11:29 PM, 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 >> --- >> drivers/spi/exynos_spi.c | 62 ++++++++++++++++++++++++++++++++++++++++------ >> 1 files changed, 54 insertions(+), 8 deletions(-) >> >> diff --git a/drivers/spi/exynos_spi.c b/drivers/spi/exynos_spi.c >> index be60ada..09e88d5 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) >> @@ -107,6 +108,8 @@ 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); >> @@ -219,17 +222,23 @@ 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, preamable_count = 0; > > preamable_count: the name is misspelled, and the variable is never modified. > >> + 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. >> @@ -240,6 +249,7 @@ 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; >> >> @@ -252,13 +262,41 @@ static void spi_rx_tx(struct exynos_spi_slave *spi_slave, int todo, >> } >> if (rx_lvl > 0 && in_bytes) { >> temp = readl(®s->rx_data); >> - if (rxp) >> + if (!rxp && !stopping) { >> + in_bytes--; >> + } else if (spi_slave->skip_preamble) { >> + if (temp == SPI_PREAMBLE_END_BYTE) { >> + spi_slave->skip_preamble = 0; >> + stopping = 0; >> + } >> + } else { >> *rxp++ = temp; >> - in_bytes--; >> + in_bytes--; >> + } >> + 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. >> + */ >> + else if (in_bytes && !toread) { >> + assert(!out_bytes); >> + toread = out_bytes = 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); >> + printf("count = %d\n", preamable_count); >> + return -1; >> } >> } >> *dinp = rxp; >> *doutp = txp; >> + return 0; >> } >> >> /** >> @@ -278,6 +316,7 @@ 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) { >> @@ -291,16 +330,22 @@ 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); >> } >> >> /* 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; >> } >> >> /** >> @@ -327,6 +372,7 @@ 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; > > who sets this bit in the 'mode' field? This is set by whoever creates the slave - in the case of snow it is cros_ec. Regards, Simon