From: Rajeshwari Shinde <rajeshwar...@samsung.com>
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 <s...@chromium.org>
Signed-off-by: Rajeshwari Shinde <rajeshwar...@samsung.com>
---
Changes in v2:
- Remove preamable_count variable which is not really needed
- Fix checkpatch warning (multiple assignments)
drivers/spi/exynos_spi.c | 62 +++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 54 insertions(+), 8 deletions(-)
diff --git a/drivers/spi/exynos_spi.c b/drivers/spi/exynos_spi.c
index 607e1cd..b7b2ea5 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 +247,7 @@ 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;
@@ -250,13 +260,41 @@ 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);
+ 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 +314,7 @@ 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 +328,22 @@ 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;
}
/**
@@ -325,6 +370,7 @@ 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;
}
/**
--
1.8.2.1
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