spi/spi_mpc8xxx: Fix QE mode Litte Endian

QE mode uses Little Endian so words > 8 bits are byte swapped.
Workaround this by always enforcing wordsize 8 for words
> 8 bits. Unfortunately this will not work for LSB transfers
where wordsize is > 8 bits so disable these for now.

Also move the different quirks into its own function to keep
mpc8xxx_spi_setup_transfer() sane.

Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Acked-by: Anton Vorontsov <cbouatmailru@gmail.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

diff --git a/drivers/spi/spi_mpc8xxx.c b/drivers/spi/spi_mpc8xxx.c
index 0dfc482..66517ce 100644 (file)
--- a/drivers/spi/spi_mpc8xxx.c
+++ b/drivers/spi/spi_mpc8xxx.c
@@ -286,36 +286,12 @@ static void mpc8xxx_spi_chipselect(struct spi_device *spi, int value)
        }
 }
 
-static
-int mpc8xxx_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
+static int
+mspi_apply_cpu_mode_quirks(struct spi_mpc8xxx_cs *cs,
+                          struct spi_device *spi,
+                          struct mpc8xxx_spi *mpc8xxx_spi,
+                          int bits_per_word)
 {
-       struct mpc8xxx_spi *mpc8xxx_spi;
-       u8 bits_per_word, pm;
-       u32 hz;
-       struct spi_mpc8xxx_cs   *cs = spi->controller_state;
-
-       mpc8xxx_spi = spi_master_get_devdata(spi->master);
-
-       if (t) {
-               bits_per_word = t->bits_per_word;
-               hz = t->speed_hz;
-       } else {
-               bits_per_word = 0;
-               hz = 0;
-       }
-
-       /* spi_transfer level calls that work per-word */
-       if (!bits_per_word)
-               bits_per_word = spi->bits_per_word;
-
-       /* Make sure its a bit width we support [4..16, 32] */
-       if ((bits_per_word < 4)
-           || ((bits_per_word > 16) && (bits_per_word != 32)))
-               return -EINVAL;
-
-       if (!hz)
-               hz = spi->max_speed_hz;
-
        cs->rx_shift = 0;
        cs->tx_shift = 0;
        if (bits_per_word <= 8) {
@@ -339,19 +315,82 @@ int mpc8xxx_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
                return -EINVAL;
 
        if (mpc8xxx_spi->flags & SPI_QE_CPU_MODE &&
-                       spi->mode & SPI_LSB_FIRST) {
+           spi->mode & SPI_LSB_FIRST) {
                cs->tx_shift = 0;
                if (bits_per_word <= 8)
                        cs->rx_shift = 8;
                else
                        cs->rx_shift = 0;
        }
-
        mpc8xxx_spi->rx_shift = cs->rx_shift;
        mpc8xxx_spi->tx_shift = cs->tx_shift;
        mpc8xxx_spi->get_rx = cs->get_rx;
        mpc8xxx_spi->get_tx = cs->get_tx;
 
+       return bits_per_word;
+}
+
+static int
+mspi_apply_qe_mode_quirks(struct spi_mpc8xxx_cs *cs,
+                         struct spi_device *spi,
+                         int bits_per_word)
+{
+       /* QE uses Little Endian for words > 8
+        * so transform all words > 8 into 8 bits
+        * Unfortnatly that doesn't work for LSB so
+        * reject these for now */
+       /* Note: 32 bits word, LSB works iff
+        * tfcr/rfcr is set to CPMFCR_GBL */
+       if (spi->mode & SPI_LSB_FIRST &&
+           bits_per_word > 8)
+               return -EINVAL;
+       if (bits_per_word > 8)
+               return 8; /* pretend its 8 bits */
+       return bits_per_word;
+}
+
+static
+int mpc8xxx_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
+{
+       struct mpc8xxx_spi *mpc8xxx_spi;
+       int bits_per_word;
+       u8 pm;
+       u32 hz;
+       struct spi_mpc8xxx_cs   *cs = spi->controller_state;
+
+       mpc8xxx_spi = spi_master_get_devdata(spi->master);
+
+       if (t) {
+               bits_per_word = t->bits_per_word;
+               hz = t->speed_hz;
+       } else {
+               bits_per_word = 0;
+               hz = 0;
+       }
+
+       /* spi_transfer level calls that work per-word */
+       if (!bits_per_word)
+               bits_per_word = spi->bits_per_word;
+
+       /* Make sure its a bit width we support [4..16, 32] */
+       if ((bits_per_word < 4)
+           || ((bits_per_word > 16) && (bits_per_word != 32)))
+               return -EINVAL;
+
+       if (!hz)
+               hz = spi->max_speed_hz;
+
+       if (!(mpc8xxx_spi->flags & SPI_CPM_MODE))
+               bits_per_word = mspi_apply_cpu_mode_quirks(cs, spi,
+                                                          mpc8xxx_spi,
+                                                          bits_per_word);
+       else if (mpc8xxx_spi->flags & SPI_QE)
+               bits_per_word = mspi_apply_qe_mode_quirks(cs, spi,
+                                                         bits_per_word);
+
+       if (bits_per_word < 0)
+               return bits_per_word;
+
        if (bits_per_word == 32)
                bits_per_word = 0;
        else