2015-02-17 19:04:00

by Mugunthan V N

[permalink] [raw]

Subject: [PATCH 1/1] drivers: spi: ti-qspi: wait for busy bit clear before data write/read

---

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 <[email protected]>
---
drivers/spi/spi-ti-qspi.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)

diff --git a/drivers/spi/spi-ti-qspi.c b/drivers/spi/spi-ti-qspi.c
index 884a716..5c06168 100644
--- a/drivers/spi/spi-ti-qspi.c
+++ b/drivers/spi/spi-ti-qspi.c
@@ -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)) {
--
2.2.1.62.g3f15098

2015-02-21 09:30:18

by Mark Brown

[permalink] [raw]

Subject: Re: [PATCH 1/1] drivers: spi: ti-qspi: wait for busy bit clear before data write/read

---

On Wed, Feb 18, 2015 at 12:33:51AM +0530, Mugunthan V N wrote:
> 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.

Applied, thanks.

---

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