[PATCH 3/3] spi: spi-xilinx: Add run run-time endian detection

[Michal Simek]

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

Signed-off-by: Michal Simek <michal.si...@xilinx.com>
---
 drivers/mfd/timberdale.c       |  1 -
 drivers/spi/spi-xilinx.c       | 29 +++++++++++++++++++++--------
 include/linux/spi/xilinx_spi.h |  1 -
 3 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/drivers/mfd/timberdale.c b/drivers/mfd/timberdale.c
index 59e0ee2..0c1fcbc 100644
--- a/drivers/mfd/timberdale.c
+++ b/drivers/mfd/timberdale.c
@@ -145,7 +145,6 @@ static struct spi_board_info 
timberdale_spi_8bit_board_info[] = {

 static struct xspi_platform_data timberdale_xspi_platform_data = {
        .num_chipselect = 3,
-       .little_endian = true,
        /* bits per word and devices will be filled in runtime depending
         * on the HW config
         */
diff --git a/drivers/spi/spi-xilinx.c b/drivers/spi/spi-xilinx.c
index d690756..0b7b8d7 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
@@ -355,11 +356,12 @@ 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)
@@ -395,13 +397,25 @@ 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;
@@ -465,14 +479,13 @@ 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;
        }

@@ -504,7 +517,7 @@ 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;

diff --git a/include/linux/spi/xilinx_spi.h b/include/linux/spi/xilinx_spi.h
index 6f17278..333ecdf 100644
--- a/include/linux/spi/xilinx_spi.h
+++ b/include/linux/spi/xilinx_spi.h
@@ -11,7 +11,6 @@
  */
 struct xspi_platform_data {
        u16 num_chipselect;
-       bool little_endian;
        u8 bits_per_word;
        struct spi_board_info *devices;
        u8 num_devices;
--
1.8.2.3

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