spi: mxs: Introduce spi_cs_is_valid()

[karo-tx-uboot.git] / drivers / spi / mxs_spi.c

diff --git a/drivers/spi/mxs_spi.c b/drivers/spi/mxs_spi.c
index 4c27fef3d183bc9a34ca0dc995cc6d662681bbee..e7237e720a40ca785922f4eb0182aedbc68d2a98 100644 (file)
--- a/drivers/spi/mxs_spi.c
+++ b/drivers/spi/mxs_spi.c
@@ -51,14 +51,23 @@ void spi_init(void)
 {
 }
 
+int spi_cs_is_valid(unsigned int bus, unsigned int cs)
+{
+       /* MXS SPI: 4 ports and 3 chip selects maximum */
+       if (bus > 3 || cs > 2)
+               return 0;
+       else
+               return 1;
+}
+
 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
                                  unsigned int max_hz, unsigned int mode)
 {
        struct mxs_spi_slave *mxs_slave;
        uint32_t addr;
 
-       if (bus > 3) {
-               printf("MXS SPI: Max bus number is 3\n");
+       if (!spi_cs_is_valid(bus, cs)) {
+               printf("mxs_spi: invalid bus %d / chip select %d\n", bus, cs);
                return NULL;
        }
 
@@ -129,9 +138,15 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
        int len = bitlen / 8;
        const char *tx = dout;
        char *rx = din;
-
-       if (bitlen == 0)
-               return 0;
+       char dummy;
+
+       if (bitlen == 0) {
+               if (flags & SPI_XFER_END) {
+                       rx = &dummy;
+                       len = 1;
+               } else
+                       return 0;
+       }
 
        if (!rx && !tx)
                return 0;
@@ -156,7 +171,7 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
                if (mx28_wait_mask_set(&ssp_regs->hw_ssp_ctrl0_reg,
                        SSP_CTRL0_RUN, MXS_SPI_MAX_TIMEOUT)) {
                        printf("MXS SPI: Timeout waiting for start\n");
-                       return -1;
+                       return -ETIMEDOUT;
                }
 
                if (tx)
@@ -168,7 +183,7 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
                        if (mx28_wait_mask_clr(&ssp_regs->hw_ssp_status_reg,
                                SSP_STATUS_FIFO_EMPTY, MXS_SPI_MAX_TIMEOUT)) {
                                printf("MXS SPI: Timeout waiting for data\n");
-                               return -1;
+                               return -ETIMEDOUT;
                        }
 
                        *rx = readl(&ssp_regs->hw_ssp_data);
@@ -178,7 +193,7 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
                if (mx28_wait_mask_clr(&ssp_regs->hw_ssp_ctrl0_reg,
                        SSP_CTRL0_RUN, MXS_SPI_MAX_TIMEOUT)) {
                        printf("MXS SPI: Timeout waiting for finish\n");
-                       return -1;
+                       return -ETIMEDOUT;
                }
        }