spi: spi-xilinx: Add run run-time endian detection

Do not load endian value from platform data
and rather autodetect it.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

1 files changed, 21 insertions, 8 deletions

diff --git a/drivers/spi/spi-xilinx.c b/drivers/spi/spi-xilinx.c
index e1d769607425..bb6ae4ee7dea 100644
--- a/drivers/spi/spi-xilinx.c
+++ b/drivers/spi/spi-xilinx.c
@@ -30,6 +30,7 @@
  */
 #define XSPI_CR_OFFSET          0x60    /* Control Register */
 
+#define XSPI_CR_LOOP            0x01
 #define XSPI_CR_ENABLE          0x02
 #define XSPI_CR_MASTER_MODE     0x04
 #define XSPI_CR_CPOL            0x08
@@ -359,11 +360,12 @@ static const struct of_device_id xilinx_spi_of_match[] = {
 MODULE_DEVICE_TABLE(of, xilinx_spi_of_match);
 
 struct spi_master *xilinx_spi_init(struct device *dev, struct resource *mem,
-        u32 irq, s16 bus_num, int num_cs, int little_endian, int bits_per_word)
+        u32 irq, s16 bus_num, int num_cs, int bits_per_word)
 {
         struct spi_master *master;
         struct xilinx_spi *xspi;
         int ret;
+        u32 tmp;
 
         master = spi_alloc_master(dev, sizeof(struct xilinx_spi));
         if (!master)
@@ -396,13 +398,25 @@ struct spi_master *xilinx_spi_init(struct device *dev, struct resource *mem,
 
         xspi->mem = *mem;
         xspi->irq = irq;
-        if (little_endian) {
-                xspi->read_fn = xspi_read32;
-                xspi->write_fn = xspi_write32;
-        } else {
+
+        /*
+         * Detect endianess on the IP via loop bit in CR. Detection
+         * must be done before reset is sent because incorrect reset
+         * value generates error interrupt.
+         * Setup little endian helper functions first and try to use them
+         * and check if bit was correctly setup or not.
+         */
+        xspi->read_fn = xspi_read32;
+        xspi->write_fn = xspi_write32;
+
+        xspi->write_fn(XSPI_CR_LOOP, xspi->regs + XSPI_CR_OFFSET);
+        tmp = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET);
+        tmp &= XSPI_CR_LOOP;
+        if (tmp != XSPI_CR_LOOP) {
                 xspi->read_fn = xspi_read32_be;
                 xspi->write_fn = xspi_write32_be;
         }
+
         xspi->bits_per_word = bits_per_word;
         if (xspi->bits_per_word == 8) {
                 xspi->tx_fn = xspi_tx8;
@@ -466,14 +480,13 @@ static int xilinx_spi_probe(struct platform_device *dev)
 {
         struct xspi_platform_data *pdata;
         struct resource *r;
-        int irq, num_cs = 0, little_endian = 0, bits_per_word = 8;
+        int irq, num_cs = 0, bits_per_word = 8;
         struct spi_master *master;
         u8 i;
 
         pdata = dev->dev.platform_data;
         if (pdata) {
                 num_cs = pdata->num_chipselect;
-                little_endian = pdata->little_endian;
                 bits_per_word = pdata->bits_per_word;
         }
 
@@ -505,7 +518,7 @@ static int xilinx_spi_probe(struct platform_device *dev)
                 return -ENXIO;
 
         master = xilinx_spi_init(&dev->dev, r, irq, dev->id, num_cs,
-                                 little_endian, bits_per_word);
+                                 bits_per_word);
         if (!master)
                 return -ENODEV;