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Subject[PATCH v3 3/6] spi: sun6i: restrict transfer length in PIO-mode
Date
There is no need to handle 3/4 empty interrupt as the maximum
supported transfer length in PIO mode is equal to FIFO depth,
i.e. 128 bytes for sun6i and 64 bytes for sun8i SoCs.

Changes in v3:
1) Restored processing of 3/4 FIFO full interrupt.

Signed-off-by: Sergey Suloev <ssuloev@orpaltech.com>
---
drivers/spi/spi-sun6i.c | 41 +++++++++++++++++------------------------
1 file changed, 17 insertions(+), 24 deletions(-)

diff --git a/drivers/spi/spi-sun6i.c b/drivers/spi/spi-sun6i.c
index 78acc1f..c09ad10 100644
--- a/drivers/spi/spi-sun6i.c
+++ b/drivers/spi/spi-sun6i.c
@@ -207,7 +207,10 @@ static void sun6i_spi_set_cs(struct spi_device *spi, bool enable)

static size_t sun6i_spi_max_transfer_size(struct spi_device *spi)
{
- return SUN6I_MAX_XFER_SIZE - 1;
+ struct spi_master *master = spi->master;
+ struct sun6i_spi *sspi = spi_master_get_devdata(master);
+
+ return sspi->fifo_depth;
}

static int sun6i_spi_prepare_message(struct spi_master *master,
@@ -255,8 +258,14 @@ static int sun6i_spi_transfer_one(struct spi_master *master,
int ret = 0;
u32 reg;

- if (tfr->len > SUN6I_MAX_XFER_SIZE)
- return -EINVAL;
+ /* A zero length transfer never finishes if programmed
+ in the hardware */
+ if (!tfr->len)
+ return 0;
+
+ /* Don't support transfer larger than the FIFO */
+ if (tfr->len > sspi->fifo_depth)
+ return -EMSGSIZE;

reinit_completion(&sspi->done);
sspi->tx_buf = tfr->tx_buf;
@@ -278,8 +287,7 @@ static int sun6i_spi_transfer_one(struct spi_master *master,
*/
trig_level = sspi->fifo_depth / 4 * 3;
sun6i_spi_write(sspi, SUN6I_FIFO_CTL_REG,
- (trig_level << SUN6I_FIFO_CTL_RF_RDY_TRIG_LEVEL_BITS) |
- (trig_level << SUN6I_FIFO_CTL_TF_ERQ_TRIG_LEVEL_BITS));
+ (trig_level << SUN6I_FIFO_CTL_RF_RDY_TRIG_LEVEL_BITS));


reg = sun6i_spi_read(sspi, SUN6I_TFR_CTL_REG);
@@ -343,11 +351,8 @@ static int sun6i_spi_transfer_one(struct spi_master *master,
sun6i_spi_fill_fifo(sspi, sspi->fifo_depth);

/* Enable the interrupts */
- sun6i_spi_write(sspi, SUN6I_INT_CTL_REG, SUN6I_INT_CTL_TC);
sun6i_spi_enable_interrupt(sspi, SUN6I_INT_CTL_TC |
SUN6I_INT_CTL_RF_RDY);
- if (tx_len > sspi->fifo_depth)
- sun6i_spi_enable_interrupt(sspi, SUN6I_INT_CTL_TF_ERQ);

/* Start the transfer */
reg = sun6i_spi_read(sspi, SUN6I_TFR_CTL_REG);
@@ -376,7 +381,9 @@ out:
static irqreturn_t sun6i_spi_handler(int irq, void *dev_id)
{
struct sun6i_spi *sspi = dev_id;
- u32 status = sun6i_spi_read(sspi, SUN6I_INT_STA_REG);
+ u32 status;
+
+ status = sun6i_spi_read(sspi, SUN6I_INT_STA_REG);

/* Transfer complete */
if (status & SUN6I_INT_CTL_TC) {
@@ -388,26 +395,12 @@ static irqreturn_t sun6i_spi_handler(int irq, void *dev_id)

/* Receive FIFO 3/4 full */
if (status & SUN6I_INT_CTL_RF_RDY) {
- sun6i_spi_drain_fifo(sspi, SUN6I_FIFO_DEPTH);
+ sun6i_spi_drain_fifo(sspi, sspi->fifo_depth);
/* Only clear the interrupt _after_ draining the FIFO */
sun6i_spi_write(sspi, SUN6I_INT_STA_REG, SUN6I_INT_CTL_RF_RDY);
return IRQ_HANDLED;
}

- /* Transmit FIFO 3/4 empty */
- if (status & SUN6I_INT_CTL_TF_ERQ) {
- sun6i_spi_fill_fifo(sspi, SUN6I_FIFO_DEPTH);
-
- if (!sspi->len)
- /* nothing left to transmit */
- sun6i_spi_disable_interrupt(sspi, SUN6I_INT_CTL_TF_ERQ);
-
- /* Only clear the interrupt _after_ re-seeding the FIFO */
- sun6i_spi_write(sspi, SUN6I_INT_STA_REG, SUN6I_INT_CTL_TF_ERQ);
-
- return IRQ_HANDLED;
- }
-
return IRQ_NONE;
}

--
2.16.2
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