spi: oc_tiny_spi: Refactor to simplify spi_xfer implementation

Currently we have similar code for (txp && rxp), (txp && !rxp), (!rxp & txp), and (!txp && !rxp) cases. This patch refactors the code a bit to avoid duplicate similar code.

Signed-off-by Axel Lin <[email protected]>

---
Hi Thomas,
This path is similar to the patch I sent for spi-oc-tiny.c linux driver. I'd appreciate if you can review and test this patch. Regards,
Axel

 drivers/spi/oc_tiny_spi.c | 85 ++++++-----------------------------------------
 1 file changed, 11 insertions(+), 74 deletions(-)

drivers/spi/oc_tiny_spi.c +11 -75

index 4de5d00..a8c1dfd 100644
@@ -158,85 +158,22 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
                spi_cs_activate(slave);
 
        /* we need to tighten the transfer loop */
-       if (txp && rxp) {
-               writeb(*txp++, &regs->txdata);
-               if (bytes > 1) {
-                       writeb(*txp++, &regs->txdata);
-                       for (i = 2; i < bytes; i++) {
-                               u8 rx, tx = *txp++;
-                               while (!(readb(&regs->status) &
-                                        TINY_SPI_STATUS_TXR))
+       writeb(txp ? *txp++ : CONFIG_TINY_SPI_IDLE_VAL, &regs->txdata);
+       for (i = 1; i < bytes; i++) {
+               writeb(txp ? *txp++ : CONFIG_TINY_SPI_IDLE_VAL, &regs->txdata);
+
+               if (rxp || (i != bytes - 1)) {
+                       while (!(readb(&regs->status) & TINY_SPI_STATUS_TXR))
                                        ;
-                               rx = readb(&regs->txdata);
-                               writeb(tx, &regs->txdata);
-                               *rxp++ = rx;
-                       }
-                       while (!(readb(&regs->status) &
-                                TINY_SPI_STATUS_TXR))
-                               ;
-                       *rxp++ = readb(&regs->txdata);
                }
-               while (!(readb(&regs->status) &
-                        TINY_SPI_STATUS_TXE))
-                       ;
-               *rxp++ = readb(&regs->rxdata);
-       } else if (rxp) {
-               writeb(CONFIG_TINY_SPI_IDLE_VAL, &regs->txdata);
-               if (bytes > 1) {
-                       writeb(CONFIG_TINY_SPI_IDLE_VAL,
-                              &regs->txdata);
-                       for (i = 2; i < bytes; i++) {
-                               u8 rx;
-                               while (!(readb(&regs->status) &
-                                        TINY_SPI_STATUS_TXR))
-                                       ;
-                               rx = readb(&regs->txdata);
-                               writeb(CONFIG_TINY_SPI_IDLE_VAL,
-                                      &regs->txdata);
-                               *rxp++ = rx;
-                       }
-                       while (!(readb(&regs->status) &
-                                TINY_SPI_STATUS_TXR))
-                               ;
+
+               if (rxp)
                        *rxp++ = readb(&regs->txdata);
-               }
-               while (!(readb(&regs->status) &
-                        TINY_SPI_STATUS_TXE))
+       }
+       while (!(readb(&regs->status) & TINY_SPI_STATUS_TXE))
                        ;
+       if (rxp)
                *rxp++ = readb(&regs->rxdata);
-       } else if (txp) {
-               writeb(*txp++, &regs->txdata);
-               if (bytes > 1) {
-                       writeb(*txp++, &regs->txdata);
-                       for (i = 2; i < bytes; i++) {
-                               u8 tx = *txp++;
-                               while (!(readb(&regs->status) &
-                                        TINY_SPI_STATUS_TXR))
-                                       ;
-                               writeb(tx, &regs->txdata);
-                       }
-               }
-               while (!(readb(&regs->status) &
-                        TINY_SPI_STATUS_TXE))
-                       ;
-       } else {
-               writeb(CONFIG_TINY_SPI_IDLE_VAL, &regs->txdata);
-               if (bytes > 1) {
-                       writeb(CONFIG_TINY_SPI_IDLE_VAL,
-                              &regs->txdata);
-                       for (i = 2; i < bytes; i++) {
-                               while (!(readb(&regs->status) &
-                                        TINY_SPI_STATUS_TXR))
-                                       ;
-                               writeb(CONFIG_TINY_SPI_IDLE_VAL,
-                                      &regs->txdata);
-                       }
-               }
-               while (!(readb(&regs->status) &
-                        TINY_SPI_STATUS_TXE))
-                       ;
-       }
-
  done:
        if (flags & SPI_XFER_END)
                spi_cs_deactivate(slave);
--

1.8.1.2

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