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drivers: spi: ti-qspi: wait for busy bit clear before data write/read

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Data corruption is seen while reading/writing large data from/to qspi
device because the data register is over written or read before data
is ready which is denoted by busy bit in status register. SO adding
a busy bit check before writing/reading data to/from qspi device.

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Mugunthan V N 2015-02-18 00:33:51 +05:30 committed by Mark Brown
parent 66886337bf
commit 0061104764
1 changed files with 22 additions and 0 deletions
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22
drivers/spi/spi-ti-qspi.c
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@ -101,6 +101,7 @@ struct ti_qspi {
#define QSPI_FLEN(n) ((n - 1) << 0)
/* STATUS REGISTER */
#define BUSY 0x01
#define WC 0x02
/* INTERRUPT REGISTER */
@ -199,6 +200,21 @@ static void ti_qspi_restore_ctx(struct ti_qspi *qspi)
ti_qspi_write(qspi, ctx_reg->clkctrl, QSPI_SPI_CLOCK_CNTRL_REG);
}
static inline u32 qspi_is_busy(struct ti_qspi *qspi)
{
u32 stat;
unsigned long timeout = jiffies + QSPI_COMPLETION_TIMEOUT;
stat = ti_qspi_read(qspi, QSPI_SPI_STATUS_REG);
while ((stat & BUSY) && time_after(timeout, jiffies)) {
cpu_relax();
stat = ti_qspi_read(qspi, QSPI_SPI_STATUS_REG);
}
WARN(stat & BUSY, "qspi busy\n");
return stat & BUSY;
}
static int qspi_write_msg(struct ti_qspi *qspi, struct spi_transfer *t)
{
int wlen, count;
@ -211,6 +227,9 @@ static int qspi_write_msg(struct ti_qspi *qspi, struct spi_transfer *t)
wlen = t->bits_per_word >> 3; /* in bytes */
while (count) {
if (qspi_is_busy(qspi))
return -EBUSY;
switch (wlen) {
case 1:
dev_dbg(qspi->dev, "tx cmd %08x dc %08x data %02x\n",
@ -266,6 +285,9 @@ static int qspi_read_msg(struct ti_qspi *qspi, struct spi_transfer *t)
while (count) {
dev_dbg(qspi->dev, "rx cmd %08x dc %08x\n", cmd, qspi->dc);
if (qspi_is_busy(qspi))
return -EBUSY;
ti_qspi_write(qspi, cmd, QSPI_SPI_CMD_REG);
if (!wait_for_completion_timeout(&qspi->transfer_complete,
QSPI_COMPLETION_TIMEOUT)) {