spi: s3c64xx: support interrupt based pio mode

Support interrupt based pio mode to optimize cpu usage.
When transmitting data size is larget than 32 bytes, operates with
interrupt based pio mode.

By using the FIFORDY INT, an interrupt can be triggered when
the desired size of data has been received. Using this, we can support
interrupt based pio mode.

Signed-off-by: Jaewon Kim <jaewon02.kim@samsung.com
Link: https://lore.kernel.org/r/20230502062813.112434-4-jaewon02.kim@samsung.com
Signed-off-by: Mark Brown <broonie@kernel.org

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index 38cc2068afcefd64d1c063588898d8d9e58a03a1..f79732ff3a2733b289d123b20a3ee7e0792b2051 100644 (file)
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -58,6 +58,8 @@
 #define S3C64XX_SPI_MODE_BUS_TSZ_HALFWORD      (1<<17)
 #define S3C64XX_SPI_MODE_BUS_TSZ_WORD          (2<<17)
 #define S3C64XX_SPI_MODE_BUS_TSZ_MASK          (3<<17)
+#define S3C64XX_SPI_MODE_RX_RDY_LVL            GENMASK(16, 11)
+#define S3C64XX_SPI_MODE_RX_RDY_LVL_SHIFT      11
 #define S3C64XX_SPI_MODE_SELF_LOOPBACK         (1<<3)
 #define S3C64XX_SPI_MODE_RXDMA_ON              (1<<2)
 #define S3C64XX_SPI_MODE_TXDMA_ON              (1<<1)
@@ -114,6 +116,8 @@
 
 #define S3C64XX_SPI_TRAILCNT           S3C64XX_SPI_MAX_TRAILCNT
 
+#define S3C64XX_SPI_POLLING_SIZE       32
+
 #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
 #define is_polling(x)  (x->cntrlr_info->polling)
 
@@ -552,7 +556,7 @@ static int s3c64xx_wait_for_dma(struct s3c64xx_spi_driver_data *sdd,
 }
 
 static int s3c64xx_wait_for_pio(struct s3c64xx_spi_driver_data *sdd,
-                               struct spi_transfer *xfer)
+                               struct spi_transfer *xfer, bool use_irq)
 {
        void __iomem *regs = sdd->regs;
        unsigned long val;
@@ -573,6 +577,12 @@ static int s3c64xx_wait_for_pio(struct s3c64xx_spi_driver_data *sdd,
        if (RX_FIFO_LVL(status, sdd) < xfer->len)
                usleep_range(time_us / 2, time_us);
 
+       if (use_irq) {
+               val = msecs_to_jiffies(ms);
+               if (!wait_for_completion_timeout(&sdd->xfer_completion, val))
+                       return -EIO;
+       }
+
        val = msecs_to_loops(ms);
        do {
                status = readl(regs + S3C64XX_SPI_STATUS);
@@ -735,10 +745,13 @@ static int s3c64xx_spi_transfer_one(struct spi_master *master,
        void *rx_buf = NULL;
        int target_len = 0, origin_len = 0;
        int use_dma = 0;
+       bool use_irq = false;
        int status;
        u32 speed;
        u8 bpw;
        unsigned long flags;
+       u32 rdy_lv;
+       u32 val;
 
        reinit_completion(&sdd->xfer_completion);
 
@@ -759,17 +772,46 @@ static int s3c64xx_spi_transfer_one(struct spi_master *master,
            sdd->rx_dma.ch && sdd->tx_dma.ch) {
                use_dma = 1;
 
-       } else if (xfer->len > fifo_len) {
+       } else if (xfer->len >= fifo_len) {
                tx_buf = xfer->tx_buf;
                rx_buf = xfer->rx_buf;
                origin_len = xfer->len;
-
                target_len = xfer->len;
-               if (xfer->len > fifo_len)
-                       xfer->len = fifo_len;
+               xfer->len = fifo_len - 1;
        }
 
        do {
+               /* transfer size is greater than 32, change to IRQ mode */
+               if (xfer->len > S3C64XX_SPI_POLLING_SIZE)
+                       use_irq = true;
+
+               if (use_irq) {
+                       reinit_completion(&sdd->xfer_completion);
+
+                       rdy_lv = xfer->len;
+                       /* Setup RDY_FIFO trigger Level
+                        * RDY_LVL =
+                        * fifo_lvl up to 64 byte -> N bytes
+                        *               128 byte -> RDY_LVL * 2 bytes
+                        *               256 byte -> RDY_LVL * 4 bytes
+                        */
+                       if (fifo_len == 128)
+                               rdy_lv /= 2;
+                       else if (fifo_len == 256)
+                               rdy_lv /= 4;
+
+                       val = readl(sdd->regs + S3C64XX_SPI_MODE_CFG);
+                       val &= ~S3C64XX_SPI_MODE_RX_RDY_LVL;
+                       val |= (rdy_lv << S3C64XX_SPI_MODE_RX_RDY_LVL_SHIFT);
+                       writel(val, sdd->regs + S3C64XX_SPI_MODE_CFG);
+
+                       /* Enable FIFO_RDY_EN IRQ */
+                       val = readl(sdd->regs + S3C64XX_SPI_INT_EN);
+                       writel((val | S3C64XX_SPI_INT_RX_FIFORDY_EN),
+                                       sdd->regs + S3C64XX_SPI_INT_EN);
+
+               }
+
                spin_lock_irqsave(&sdd->lock, flags);
 
                /* Pending only which is to be done */
@@ -791,7 +833,7 @@ static int s3c64xx_spi_transfer_one(struct spi_master *master,
                if (use_dma)
                        status = s3c64xx_wait_for_dma(sdd, xfer);
                else
-                       status = s3c64xx_wait_for_pio(sdd, xfer);
+                       status = s3c64xx_wait_for_pio(sdd, xfer, use_irq);
 
                if (status) {
                        dev_err(&spi->dev,
@@ -830,8 +872,8 @@ static int s3c64xx_spi_transfer_one(struct spi_master *master,
                        if (xfer->rx_buf)
                                xfer->rx_buf += xfer->len;
 
-                       if (target_len > fifo_len)
-                               xfer->len = fifo_len;
+                       if (target_len >= fifo_len)
+                               xfer->len = fifo_len - 1;
                        else
                                xfer->len = target_len;
                }
@@ -1001,6 +1043,14 @@ static irqreturn_t s3c64xx_spi_irq(int irq, void *data)
                dev_err(&spi->dev, "TX underrun\n");
        }
 
+       if (val & S3C64XX_SPI_ST_RX_FIFORDY) {
+               complete(&sdd->xfer_completion);
+               /* No pending clear irq, turn-off INT_EN_RX_FIFO_RDY */
+               val = readl(sdd->regs + S3C64XX_SPI_INT_EN);
+               writel((val & ~S3C64XX_SPI_INT_RX_FIFORDY_EN),
+                               sdd->regs + S3C64XX_SPI_INT_EN);
+       }
+
        /* Clear the pending irq by setting and then clearing it */
        writel(clr, sdd->regs + S3C64XX_SPI_PENDING_CLR);
        writel(0, sdd->regs + S3C64XX_SPI_PENDING_CLR);