[PATCH v3 3/6] spi: rockchip: Stop spi slave dma receiver when cs inactive

Jon Lin
2022-02-16T01:41:07Z

The spi which's version is higher than ver 2 will automatically
enable this feature.

If the length of master transmission is uncertain, the RK spi slave
is better to automatically stop after cs inactive instead of waiting
for xfer_completion forever.

Signed-off-by: Jon Lin <jon.lin@rock-chips.com>
---

Changes in v3: None
Changes in v2: None
Changes in v1: None

drivers/spi/spi-rockchip.c | 81 ++++++++++++++++++++++++++++++++++----
1 file changed, 73 insertions(+), 8 deletions(-)

diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
index c6a1bb09be05..5ecd0692cca1 100644
--- a/drivers/spi/spi-rockchip.c
+++ b/drivers/spi/spi-rockchip.c
@@ -133,7 +133,8 @@
#define INT_TF_OVERFLOW (1 << 1)
#define INT_RF_UNDERFLOW (1 << 2)
#define INT_RF_OVERFLOW (1 << 3)
-#define INT_RF_FULL (1 << 4)
+#define INT_RF_FULL (1 << 4)
+#define INT_CS_INACTIVE (1 << 6)

/* Bit fields in ICR, 4bit */
#define ICR_MASK 0x0f
@@ -194,6 +195,8 @@ struct rockchip_spi {
bool cs_asserted[ROCKCHIP_SPI_MAX_CS_NUM];

bool slave_abort;
+ bool cs_inactive; /* spi slave tansmition stop when cs inactive */
+ struct spi_transfer *xfer; /* Store xfer temporarily */
};

static inline void spi_enable_chip(struct rockchip_spi *rs, bool enable)
@@ -343,6 +346,15 @@ static irqreturn_t rockchip_spi_isr(int irq, void *dev_id)
struct spi_controller *ctlr = dev_id;
struct rockchip_spi *rs = spi_controller_get_devdata(ctlr);

+ /* When int_cs_inactive comes, spi slave abort */
+ if (rs->cs_inactive && readl_relaxed(rs->regs + ROCKCHIP_SPI_IMR) & INT_CS_INACTIVE) {
+ ctlr->slave_abort(ctlr);
+ writel_relaxed(0, rs->regs + ROCKCHIP_SPI_IMR);
+ writel_relaxed(0xffffffff, rs->regs + ROCKCHIP_SPI_ICR);
+
+ return IRQ_HANDLED;
+ }
+
if (rs->tx_left)
rockchip_spi_pio_writer(rs);

@@ -350,6 +362,7 @@ static irqreturn_t rockchip_spi_isr(int irq, void *dev_id)
if (!rs->rx_left) {
spi_enable_chip(rs, false);
writel_relaxed(0, rs->regs + ROCKCHIP_SPI_IMR);
+ writel_relaxed(0xffffffff, rs->regs + ROCKCHIP_SPI_ICR);
spi_finalize_current_transfer(ctlr);
}

@@ -357,14 +370,18 @@ static irqreturn_t rockchip_spi_isr(int irq, void *dev_id)
}

static int rockchip_spi_prepare_irq(struct rockchip_spi *rs,
- struct spi_transfer *xfer)
+ struct spi_controller *ctlr,
+ struct spi_transfer *xfer)
{
rs->tx = xfer->tx_buf;
rs->rx = xfer->rx_buf;
rs->tx_left = rs->tx ? xfer->len / rs->n_bytes : 0;
rs->rx_left = xfer->len / rs->n_bytes;

- writel_relaxed(INT_RF_FULL, rs->regs + ROCKCHIP_SPI_IMR);
+ if (rs->cs_inactive)
+ writel_relaxed(INT_RF_FULL | INT_CS_INACTIVE, rs->regs + ROCKCHIP_SPI_IMR);
+ else
+ writel_relaxed(INT_RF_FULL, rs->regs + ROCKCHIP_SPI_IMR);
spi_enable_chip(rs, true);

if (rs->tx_left)
@@ -383,6 +400,9 @@ static void rockchip_spi_dma_rxcb(void *data)
if (state & TXDMA && !rs->slave_abort)
return;

+ if (rs->cs_inactive)
+ writel_relaxed(0, rs->regs + ROCKCHIP_SPI_IMR);
+
spi_enable_chip(rs, false);
spi_finalize_current_transfer(ctlr);
}
@@ -423,14 +443,16 @@ static int rockchip_spi_prepare_dma(struct rockchip_spi *rs,

atomic_set(&rs->state, 0);

+ rs->tx = xfer->tx_buf;
+ rs->rx = xfer->rx_buf;
+
rxdesc = NULL;
if (xfer->rx_buf) {
struct dma_slave_config rxconf = {
.direction = DMA_DEV_TO_MEM,
.src_addr = rs->dma_addr_rx,
.src_addr_width = rs->n_bytes,
- .src_maxburst = rockchip_spi_calc_burst_size(xfer->len /
- rs->n_bytes),
+ .src_maxburst = rockchip_spi_calc_burst_size(xfer->len / rs->n_bytes),
};

dmaengine_slave_config(ctlr->dma_rx, &rxconf);
@@ -474,10 +496,13 @@ static int rockchip_spi_prepare_dma(struct rockchip_spi *rs,
/* rx must be started before tx due to spi instinct */
if (rxdesc) {
atomic_or(RXDMA, &rs->state);
- dmaengine_submit(rxdesc);
+ ctlr->dma_rx->cookie = dmaengine_submit(rxdesc);
dma_async_issue_pending(ctlr->dma_rx);
}

+ if (rs->cs_inactive)
+ writel_relaxed(INT_CS_INACTIVE, rs->regs + ROCKCHIP_SPI_IMR);
+
spi_enable_chip(rs, true);

if (txdesc) {
@@ -584,7 +609,42 @@ static size_t rockchip_spi_max_transfer_size(struct spi_device *spi)
static int rockchip_spi_slave_abort(struct spi_controller *ctlr)
{
struct rockchip_spi *rs = spi_controller_get_devdata(ctlr);
+ u32 rx_fifo_left;
+ struct dma_tx_state state;
+ enum dma_status status;
+
+ /* Get current dma rx point */
+ if (atomic_read(&rs->state) & RXDMA) {
+ dmaengine_pause(ctlr->dma_rx);
+ status = dmaengine_tx_status(ctlr->dma_rx, ctlr->dma_rx->cookie, &state);
+ if (status == DMA_ERROR) {
+ rs->rx = rs->xfer->rx_buf;
+ rs->xfer->len = 0;
+ rx_fifo_left = readl_relaxed(rs->regs + ROCKCHIP_SPI_RXFLR);
+ for (; rx_fifo_left; rx_fifo_left--)
+ readl_relaxed(rs->regs + ROCKCHIP_SPI_RXDR);
+ goto out;
+ } else {
+ rs->rx += rs->xfer->len - rs->n_bytes * state.residue;
+ }
+ }

+ /* Get the valid data left in rx fifo and set rs->xfer->len real rx size */
+ if (rs->rx) {
+ rx_fifo_left = readl_relaxed(rs->regs + ROCKCHIP_SPI_RXFLR);
+ for (; rx_fifo_left; rx_fifo_left--) {
+ u32 rxw = readl_relaxed(rs->regs + ROCKCHIP_SPI_RXDR);
+
+ if (rs->n_bytes == 1)
+ *(u8 *)rs->rx = (u8)rxw;
+ else
+ *(u16 *)rs->rx = (u16)rxw;
+ rs->rx += rs->n_bytes;
+ }
+ rs->xfer->len = (unsigned int)(rs->rx - rs->xfer->rx_buf);
+ }
+
+out:
if (atomic_read(&rs->state) & RXDMA)
dmaengine_terminate_sync(ctlr->dma_rx);
if (atomic_read(&rs->state) & TXDMA)
@@ -626,7 +686,7 @@ static int rockchip_spi_transfer_one(
}

rs->n_bytes = xfer->bits_per_word <= 8 ? 1 : 2;
-
+ rs->xfer = xfer;
use_dma = ctlr->can_dma ? ctlr->can_dma(ctlr, spi, xfer) : false;

ret = rockchip_spi_config(rs, spi, xfer, use_dma, ctlr->slave);
@@ -636,7 +696,7 @@ static int rockchip_spi_transfer_one(
if (use_dma)
return rockchip_spi_prepare_dma(rs, ctlr, xfer);

- return rockchip_spi_prepare_irq(rs, xfer);
+ return rockchip_spi_prepare_irq(rs, ctlr, xfer);
}

static bool rockchip_spi_can_dma(struct spi_controller *ctlr,
@@ -815,8 +875,13 @@ static int rockchip_spi_probe(struct platform_device *pdev)
switch (readl_relaxed(rs->regs + ROCKCHIP_SPI_VERSION)) {
case ROCKCHIP_SPI_VER2_TYPE2:
ctlr->mode_bits |= SPI_CS_HIGH;
+ if (ctlr->can_dma && slave_mode)
+ rs->cs_inactive = true;
+ else
+ rs->cs_inactive = false;
break;
default:
+ rs->cs_inactive = false;
break;
}

--
2.17.1