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authorRajeshwari Shinde <rajeshwari.s@samsung.com>2013-05-28 20:10:38 +0000
committerJagannadha Sutradharudu Teki <jaganna@xilinx.com>2013-06-03 00:04:40 +0530
commite4eaef8910df805d511b1cb9b2caafa7d2827fdc (patch)
treefc58af501f7a5e5e125133c99c349c3cc1c81d6b /drivers
parentbb786b84bdbcfe0474d53a54c82c5695494a6ab5 (diff)
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spi: exynos: Support SPI_PREAMBLE mode
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> Reviewed-by: Jagannadha Sutradharudu Teki <jagannadh.teki@gmail.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/spi/exynos_spi.c69
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;
}
/**