spi/dw_spi: unify the low level read/write routines

The original version has many duplicated codes for null/u8/u16 case,
so unify them to make it cleaner

Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

2 files changed, 26 insertions, 79 deletions

diff --git a/drivers/spi/dw_spi.c b/drivers/spi/dw_spi.c
index 9a6196461b27..c4fca3d9d45f 100644
--- a/drivers/spi/dw_spi.c
+++ b/drivers/spi/dw_spi.c
@@ -58,8 +58,6 @@ struct chip_data {
         u8 bits_per_word;
         u16 clk_div;            /* baud rate divider */
         u32 speed_hz;           /* baud rate */
-        int (*write)(struct dw_spi *dws);
-        int (*read)(struct dw_spi *dws);
         void (*cs_control)(u32 command);
 };
 
@@ -185,80 +183,45 @@ static void flush(struct dw_spi *dws)
         wait_till_not_busy(dws);
 }
 
-static int null_writer(struct dw_spi *dws)
-{
-        u8 n_bytes = dws->n_bytes;
-
-        if (!(dw_readw(dws, sr) & SR_TF_NOT_FULL)
-                || (dws->tx == dws->tx_end))
-                return 0;
-        dw_writew(dws, dr, 0);
-        dws->tx += n_bytes;
 
-        wait_till_not_busy(dws);
-        return 1;
-}
-
-static int null_reader(struct dw_spi *dws)
+static int dw_writer(struct dw_spi *dws)
 {
-        u8 n_bytes = dws->n_bytes;
+        u16 txw = 0;
 
-        while ((dw_readw(dws, sr) & SR_RF_NOT_EMPT)
-                && (dws->rx < dws->rx_end)) {
-                dw_readw(dws, dr);
-                dws->rx += n_bytes;
-        }
-        wait_till_not_busy(dws);
-        return dws->rx == dws->rx_end;
-}
-
-static int u8_writer(struct dw_spi *dws)
-{
         if (!(dw_readw(dws, sr) & SR_TF_NOT_FULL)
                 || (dws->tx == dws->tx_end))
                 return 0;
 
-        dw_writew(dws, dr, *(u8 *)(dws->tx));
-        ++dws->tx;
-
-        wait_till_not_busy(dws);
-        return 1;
-}
-
-static int u8_reader(struct dw_spi *dws)
-{
-        while ((dw_readw(dws, sr) & SR_RF_NOT_EMPT)
-                && (dws->rx < dws->rx_end)) {
-                *(u8 *)(dws->rx) = dw_readw(dws, dr);
-                ++dws->rx;
+        /* Set the tx word if the transfer's original "tx" is not null */
+        if (dws->tx_end - dws->len) {
+                if (dws->n_bytes == 1)
+                        txw = *(u8 *)(dws->tx);
+                else
+                        txw = *(u16 *)(dws->tx);
         }
 
-        wait_till_not_busy(dws);
-        return dws->rx == dws->rx_end;
-}
-
-static int u16_writer(struct dw_spi *dws)
-{
-        if (!(dw_readw(dws, sr) & SR_TF_NOT_FULL)
-                || (dws->tx == dws->tx_end))
-                return 0;
-
-        dw_writew(dws, dr, *(u16 *)(dws->tx));
-        dws->tx += 2;
+        dw_writew(dws, dr, txw);
+        dws->tx += dws->n_bytes;
 
         wait_till_not_busy(dws);
         return 1;
 }
 
-static int u16_reader(struct dw_spi *dws)
+static int dw_reader(struct dw_spi *dws)
 {
-        u16 temp;
+        u16 rxw;
 
         while ((dw_readw(dws, sr) & SR_RF_NOT_EMPT)
                 && (dws->rx < dws->rx_end)) {
-                temp = dw_readw(dws, dr);
-                *(u16 *)(dws->rx) = temp;
-                dws->rx += 2;
+                rxw = dw_readw(dws, dr);
+                /* Care rx only if the transfer's original "rx" is not null */
+                if (dws->rx_end - dws->len) {
+                        if (dws->n_bytes == 1)
+                                *(u8 *)(dws->rx) = rxw;
+                        else
+                                *(u16 *)(dws->rx) = rxw;
+                }
+                dws->rx += dws->n_bytes;
         }
 
         wait_till_not_busy(dws);
@@ -383,8 +346,8 @@ static irqreturn_t interrupt_transfer(struct dw_spi *dws)
                 left = (left > int_level) ? int_level : left;
 
                 while (left--)
-                        dws->write(dws);
-                dws->read(dws);
+                        dw_writer(dws);
+                dw_reader(dws);
 
                 /* Re-enable the IRQ if there is still data left to tx */
                 if (dws->tx_end > dws->tx)
@@ -417,13 +380,13 @@ static irqreturn_t dw_spi_irq(int irq, void *dev_id)
 /* Must be called inside pump_transfers() */
 static void poll_transfer(struct dw_spi *dws)
 {
-        while (dws->write(dws))
-                dws->read(dws);
+        while (dw_writer(dws))
+                dw_reader(dws);
         /*
          * There is a possibility that the last word of a transaction
          * will be lost if data is not ready. Re-read to solve this issue.
          */
-        dws->read(dws);
+        dw_reader(dws);
 
         dw_spi_xfer_done(dws);
 }
@@ -483,8 +446,6 @@ static void pump_transfers(unsigned long data)
         dws->tx_end = dws->tx + transfer->len;
         dws->rx = transfer->rx_buf;
         dws->rx_end = dws->rx + transfer->len;
-        dws->write = dws->tx ? chip->write : null_writer;
-        dws->read = dws->rx ? chip->read : null_reader;
         dws->cs_change = transfer->cs_change;
         dws->len = dws->cur_transfer->len;
         if (chip != dws->prev_chip)
@@ -520,18 +481,10 @@ static void pump_transfers(unsigned long data)
                 case 8:
                         dws->n_bytes = 1;
                         dws->dma_width = 1;
-                        dws->read = (dws->read != null_reader) ?
-                                        u8_reader : null_reader;
-                        dws->write = (dws->write != null_writer) ?
-                                        u8_writer : null_writer;
                         break;
                 case 16:
                         dws->n_bytes = 2;
                         dws->dma_width = 2;
-                        dws->read = (dws->read != null_reader) ?
-                                        u16_reader : null_reader;
-                        dws->write = (dws->write != null_writer) ?
-                                        u16_writer : null_writer;
                         break;
                 default:
                         printk(KERN_ERR "MRST SPI0: unsupported bits:"
@@ -733,13 +686,9 @@ static int dw_spi_setup(struct spi_device *spi)
         if (spi->bits_per_word <= 8) {
                 chip->n_bytes = 1;
                 chip->dma_width = 1;
-                chip->read = u8_reader;
-                chip->write = u8_writer;
         } else if (spi->bits_per_word <= 16) {
                 chip->n_bytes = 2;
                 chip->dma_width = 2;
-                chip->read = u16_reader;
-                chip->write = u16_writer;
         } else {
                 /* Never take >16b case for MRST SPIC */
                 dev_err(&spi->dev, "invalid wordsize\n");
diff --git a/drivers/spi/dw_spi.h b/drivers/spi/dw_spi.h
index fb0bce564844..d8aac1f4c546 100644
--- a/drivers/spi/dw_spi.h
+++ b/drivers/spi/dw_spi.h
@@ -137,8 +137,6 @@ struct dw_spi {
         u8                      max_bits_per_word;      /* maxim is 16b */
         u32                     dma_width;
         int                     cs_change;
-        int                     (*write)(struct dw_spi *dws);
-        int                     (*read)(struct dw_spi *dws);
         irqreturn_t             (*transfer_handler)(struct dw_spi *dws);
         void                    (*cs_control)(u32 command);