Merge tag 'doc-4.10-3' of git://git.lwn.net/linux

[karo-tx-linux.git] / drivers / spi / spi-sun4i.c

diff --git a/drivers/spi/spi-sun4i.c b/drivers/spi/spi-sun4i.c
index 4969dc10684a4c48135a12e46823be3afc7c5c56..c5cd635c28f388bec2cfd47b9a6c6c9dcec9e046 100644 (file)
--- a/drivers/spi/spi-sun4i.c
+++ b/drivers/spi/spi-sun4i.c
@@ -46,6 +46,8 @@
 #define SUN4I_CTL_TP                           BIT(18)
 
 #define SUN4I_INT_CTL_REG              0x0c
+#define SUN4I_INT_CTL_RF_F34                   BIT(4)
+#define SUN4I_INT_CTL_TF_E34                   BIT(12)
 #define SUN4I_INT_CTL_TC                       BIT(16)
 
 #define SUN4I_INT_STA_REG              0x10
@@ -61,11 +63,14 @@
 #define SUN4I_CLK_CTL_CDR1(div)                        (((div) & SUN4I_CLK_CTL_CDR1_MASK) << 8)
 #define SUN4I_CLK_CTL_DRS                      BIT(12)
 
+#define SUN4I_MAX_XFER_SIZE                    0xffffff
+
 #define SUN4I_BURST_CNT_REG            0x20
-#define SUN4I_BURST_CNT(cnt)                   ((cnt) & 0xffffff)
+#define SUN4I_BURST_CNT(cnt)                   ((cnt) & SUN4I_MAX_XFER_SIZE)
 
 #define SUN4I_XMIT_CNT_REG             0x24
-#define SUN4I_XMIT_CNT(cnt)                    ((cnt) & 0xffffff)
+#define SUN4I_XMIT_CNT(cnt)                    ((cnt) & SUN4I_MAX_XFER_SIZE)
+
 
 #define SUN4I_FIFO_STA_REG             0x28
 #define SUN4I_FIFO_STA_RF_CNT_MASK             0x7f
@@ -96,6 +101,31 @@ static inline void sun4i_spi_write(struct sun4i_spi *sspi, u32 reg, u32 value)
        writel(value, sspi->base_addr + reg);
 }
 
+static inline u32 sun4i_spi_get_tx_fifo_count(struct sun4i_spi *sspi)
+{
+       u32 reg = sun4i_spi_read(sspi, SUN4I_FIFO_STA_REG);
+
+       reg >>= SUN4I_FIFO_STA_TF_CNT_BITS;
+
+       return reg & SUN4I_FIFO_STA_TF_CNT_MASK;
+}
+
+static inline void sun4i_spi_enable_interrupt(struct sun4i_spi *sspi, u32 mask)
+{
+       u32 reg = sun4i_spi_read(sspi, SUN4I_INT_CTL_REG);
+
+       reg |= mask;
+       sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, reg);
+}
+
+static inline void sun4i_spi_disable_interrupt(struct sun4i_spi *sspi, u32 mask)
+{
+       u32 reg = sun4i_spi_read(sspi, SUN4I_INT_CTL_REG);
+
+       reg &= ~mask;
+       sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, reg);
+}
+
 static inline void sun4i_spi_drain_fifo(struct sun4i_spi *sspi, int len)
 {
        u32 reg, cnt;
@@ -118,10 +148,13 @@ static inline void sun4i_spi_drain_fifo(struct sun4i_spi *sspi, int len)
 
 static inline void sun4i_spi_fill_fifo(struct sun4i_spi *sspi, int len)
 {
+       u32 cnt;
        u8 byte;
 
-       if (len > sspi->len)
-               len = sspi->len;
+       /* See how much data we can fit */
+       cnt = SUN4I_FIFO_DEPTH - sun4i_spi_get_tx_fifo_count(sspi);
+
+       len = min3(len, (int)cnt, sspi->len);
 
        while (len--) {
                byte = sspi->tx_buf ? *sspi->tx_buf++ : 0;
@@ -184,10 +217,10 @@ static int sun4i_spi_transfer_one(struct spi_master *master,
        u32 reg;
 
        /* We don't support transfer larger than the FIFO */
-       if (tfr->len > SUN4I_FIFO_DEPTH)
+       if (tfr->len > SUN4I_MAX_XFER_SIZE)
                return -EMSGSIZE;
 
-       if (tfr->tx_buf && tfr->len >= SUN4I_FIFO_DEPTH)
+       if (tfr->tx_buf && tfr->len >= SUN4I_MAX_XFER_SIZE)
                return -EMSGSIZE;
 
        reinit_completion(&sspi->done);
@@ -286,7 +319,11 @@ static int sun4i_spi_transfer_one(struct spi_master *master,
        sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH - 1);
 
        /* Enable the interrupts */
-       sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, SUN4I_INT_CTL_TC);
+       sun4i_spi_enable_interrupt(sspi, SUN4I_INT_CTL_TC |
+                                        SUN4I_INT_CTL_RF_F34);
+       /* Only enable Tx FIFO interrupt if we really need it */
+       if (tx_len > SUN4I_FIFO_DEPTH)
+               sun4i_spi_enable_interrupt(sspi, SUN4I_INT_CTL_TF_E34);
 
        /* Start the transfer */
        reg = sun4i_spi_read(sspi, SUN4I_CTL_REG);
@@ -306,7 +343,6 @@ static int sun4i_spi_transfer_one(struct spi_master *master,
                goto out;
        }
 
-       sun4i_spi_drain_fifo(sspi, SUN4I_FIFO_DEPTH);
 
 out:
        sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, 0);
@@ -322,10 +358,33 @@ static irqreturn_t sun4i_spi_handler(int irq, void *dev_id)
        /* Transfer complete */
        if (status & SUN4I_INT_CTL_TC) {
                sun4i_spi_write(sspi, SUN4I_INT_STA_REG, SUN4I_INT_CTL_TC);
+               sun4i_spi_drain_fifo(sspi, SUN4I_FIFO_DEPTH);
                complete(&sspi->done);
                return IRQ_HANDLED;
        }
 
+       /* Receive FIFO 3/4 full */
+       if (status & SUN4I_INT_CTL_RF_F34) {
+               sun4i_spi_drain_fifo(sspi, SUN4I_FIFO_DEPTH);
+               /* Only clear the interrupt _after_ draining the FIFO */
+               sun4i_spi_write(sspi, SUN4I_INT_STA_REG, SUN4I_INT_CTL_RF_F34);
+               return IRQ_HANDLED;
+       }
+
+       /* Transmit FIFO 3/4 empty */
+       if (status & SUN4I_INT_CTL_TF_E34) {
+               sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH);
+
+               if (!sspi->len)
+                       /* nothing left to transmit */
+                       sun4i_spi_disable_interrupt(sspi, SUN4I_INT_CTL_TF_E34);
+
+               /* Only clear the interrupt _after_ re-seeding the FIFO */
+               sun4i_spi_write(sspi, SUN4I_INT_STA_REG, SUN4I_INT_CTL_TF_E34);
+
+               return IRQ_HANDLED;
+       }
+
        return IRQ_NONE;
 }