[PATCH v1 04/14] spi: rockchip: use atomic_t state

Emil Renner Berthing
2018-10-31T10:57:01Z

The state field is currently only used to make sure
only the last of the tx and rx dma callbacks issue
an spi_finalize_current_transfer.
Rather than using a spinlock we can get away
with just turning the state field into an atomic_t.

Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
---
drivers/spi/spi-rockchip.c | 75 +++++++++++++-------------------------
1 file changed, 25 insertions(+), 50 deletions(-)

diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
index 7fac4253075e..1c813797f963 100644
--- a/drivers/spi/spi-rockchip.c
+++ b/drivers/spi/spi-rockchip.c
@@ -142,8 +142,9 @@
#define RF_DMA_EN (1 << 0)
#define TF_DMA_EN (1 << 1)

-#define RXBUSY (1 << 0)
-#define TXBUSY (1 << 1)
+/* Driver state flags */
+#define RXDMA (1 << 0)
+#define TXDMA (1 << 1)

/* sclk_out: spi master internal logic in rk3x can support 50Mhz */
#define MAX_SCLK_OUT 50000000
@@ -169,6 +170,9 @@ struct rockchip_spi {
struct clk *apb_pclk;

void __iomem *regs;
+
+ atomic_t state;
+
/*depth of the FIFO buffer */
u32 fifo_len;
/* max bus freq supported */
@@ -187,10 +191,6 @@ struct rockchip_spi {
void *rx;
void *rx_end;

- u32 state;
- /* protect state */
- spinlock_t lock;
-
bool cs_asserted[ROCKCHIP_SPI_MAX_CS_NUM];

bool use_dma;
@@ -302,28 +302,21 @@ static int rockchip_spi_prepare_message(struct spi_master *master,
static void rockchip_spi_handle_err(struct spi_master *master,
struct spi_message *msg)
{
- unsigned long flags;
struct rockchip_spi *rs = spi_master_get_devdata(master);

- spin_lock_irqsave(&rs->lock, flags);
-
/*
* For DMA mode, we need terminate DMA channel and flush
* fifo for the next transfer if DMA thansfer timeout.
* handle_err() was called by core if transfer failed.
* Maybe it is reasonable for error handling here.
*/
- if (rs->use_dma) {
- if (rs->state & RXBUSY) {
- dmaengine_terminate_async(rs->dma_rx.ch);
- flush_fifo(rs);
- }
+ if (atomic_read(&rs->state) & TXDMA)
+ dmaengine_terminate_async(rs->dma_tx.ch);

- if (rs->state & TXBUSY)
- dmaengine_terminate_async(rs->dma_tx.ch);
+ if (atomic_read(&rs->state) & RXDMA) {
+ dmaengine_terminate_async(rs->dma_rx.ch);
+ flush_fifo(rs);
}
-
- spin_unlock_irqrestore(&rs->lock, flags);
}

static int rockchip_spi_unprepare_message(struct spi_master *master,
@@ -398,48 +391,36 @@ static int rockchip_spi_pio_transfer(struct rockchip_spi *rs)

static void rockchip_spi_dma_rxcb(void *data)
{
- unsigned long flags;
struct rockchip_spi *rs = data;
+ int state = atomic_fetch_andnot(RXDMA, &rs->state);

- spin_lock_irqsave(&rs->lock, flags);
-
- rs->state &= ~RXBUSY;
- if (!(rs->state & TXBUSY)) {
- spi_enable_chip(rs, false);
- spi_finalize_current_transfer(rs->master);
- }
+ if (state & TXDMA)
+ return;

- spin_unlock_irqrestore(&rs->lock, flags);
+ spi_enable_chip(rs, false);
+ spi_finalize_current_transfer(rs->master);
}

static void rockchip_spi_dma_txcb(void *data)
{
- unsigned long flags;
struct rockchip_spi *rs = data;
+ int state = atomic_fetch_andnot(TXDMA, &rs->state);
+
+ if (state & RXDMA)
+ return;

/* Wait until the FIFO data completely. */
wait_for_idle(rs);

- spin_lock_irqsave(&rs->lock, flags);
-
- rs->state &= ~TXBUSY;
- if (!(rs->state & RXBUSY)) {
- spi_enable_chip(rs, false);
- spi_finalize_current_transfer(rs->master);
- }
-
- spin_unlock_irqrestore(&rs->lock, flags);
+ spi_enable_chip(rs, false);
+ spi_finalize_current_transfer(rs->master);
}

static int rockchip_spi_prepare_dma(struct rockchip_spi *rs)
{
- unsigned long flags;
struct dma_async_tx_descriptor *rxdesc, *txdesc;

- spin_lock_irqsave(&rs->lock, flags);
- rs->state &= ~RXBUSY;
- rs->state &= ~TXBUSY;
- spin_unlock_irqrestore(&rs->lock, flags);
+ atomic_set(&rs->state, 0);

rxdesc = NULL;
if (rs->rx) {
@@ -490,9 +471,7 @@ static int rockchip_spi_prepare_dma(struct rockchip_spi *rs)

/* rx must be started before tx due to spi instinct */
if (rxdesc) {
- spin_lock_irqsave(&rs->lock, flags);
- rs->state |= RXBUSY;
- spin_unlock_irqrestore(&rs->lock, flags);
+ atomic_or(RXDMA, &rs->state);
dmaengine_submit(rxdesc);
dma_async_issue_pending(rs->dma_rx.ch);
}
@@ -500,9 +479,7 @@ static int rockchip_spi_prepare_dma(struct rockchip_spi *rs)
spi_enable_chip(rs, true);

if (txdesc) {
- spin_lock_irqsave(&rs->lock, flags);
- rs->state |= TXBUSY;
- spin_unlock_irqrestore(&rs->lock, flags);
+ atomic_or(TXDMA, &rs->state);
dmaengine_submit(txdesc);
dma_async_issue_pending(rs->dma_tx.ch);
}
@@ -716,8 +693,6 @@ static int rockchip_spi_probe(struct platform_device *pdev)
goto err_disable_spiclk;
}

- spin_lock_init(&rs->lock);
-
pm_runtime_set_active(&pdev->dev);
pm_runtime_enable(&pdev->dev);

--
2.19.1