spi: rockchip: use atomic_t state

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>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
index 7fac425..1c81379 100644 (file)
--- 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);