spi: fsl-spi: Re-organise transfer bits_per_word adaptation

(backported from upstream 8a5299a1278eadf1e08a598a5345c376206f171e)

For different reasons, fsl-spi driver performs bits_per_word
modifications for different reasons:
- On CPU mode, to minimise amount of interrupts
- On CPM/QE mode to work around controller byte order

For CPU mode that's done in fsl_spi_prepare_message() while
for CPM mode that's done in fsl_spi_setup_transfer().

Reunify all of it in fsl_spi_prepare_message(), and catch
impossible cases early through master's bits_per_word_mask
instead of returning EINVAL later.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/r/0ce96fe96e8b07cba0613e4097cfd94d09b8919a.1680371809.git.christophe.leroy@csgroup.eu
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/spi/spi-fsl-spi.c b/drivers/spi/spi-fsl-spi.c
index ae805f91eafa55971cf5f24cef07bc4dd82d2d96..a974074b253af600c39a22a1626723d56f14f7de 100644 (file)
--- a/drivers/spi/spi-fsl-spi.c
+++ b/drivers/spi/spi-fsl-spi.c
@@ -204,26 +204,6 @@ static int mspi_apply_cpu_mode_quirks(struct spi_mpc8xxx_cs *cs,
        return bits_per_word;
 }
 
-static int mspi_apply_qe_mode_quirks(struct spi_mpc8xxx_cs *cs,
-                               struct spi_device *spi,
-                               int bits_per_word)
-{
-       /* CPM/QE uses Little Endian for words > 8
-        * so transform 16 and 32 bits words 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 bits_per_word;
-       if (bits_per_word == 16 || bits_per_word == 32)
-               return 8; /* pretend its 8 bits */
-       return -EINVAL;
-}
-
 static int fsl_spi_setup_transfer(struct spi_device *spi,
                                        struct spi_transfer *t)
 {
@@ -251,9 +231,6 @@ static int fsl_spi_setup_transfer(struct spi_device *spi,
                bits_per_word = mspi_apply_cpu_mode_quirks(cs, spi,
                                                           mpc8xxx_spi,
                                                           bits_per_word);
-       else
-               bits_per_word = mspi_apply_qe_mode_quirks(cs, spi,
-                                                         bits_per_word);
 
        if (bits_per_word < 0)
                return bits_per_word;
@@ -371,14 +348,27 @@ static int fsl_spi_do_one_msg(struct spi_master *master,
         * In CPU mode, optimize large byte transfers to use larger
         * bits_per_word values to reduce number of interrupts taken.
         */
-       if (!(mpc8xxx_spi->flags & SPI_CPM_MODE)) {
-               list_for_each_entry(t, &m->transfers, transfer_list) {
+       list_for_each_entry(t, &m->transfers, transfer_list) {
+               if (!(mpc8xxx_spi->flags & SPI_CPM_MODE)) {
                        if (t->len < 256 || t->bits_per_word != 8)
                                continue;
                        if ((t->len & 3) == 0)
                                t->bits_per_word = 32;
                        else if ((t->len & 1) == 0)
                                t->bits_per_word = 16;
+               } else {
+                       /*
+                        * CPM/QE uses Little Endian for words > 8
+                        * so transform 16 and 32 bits words 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 (m->spi->mode & SPI_LSB_FIRST && t->bits_per_word > 8)
+                               return -EINVAL;
+                       if (t->bits_per_word == 16 || t->bits_per_word == 32)
+                               t->bits_per_word = 8; /* pretend its 8 bits */
                }
        }
 
@@ -637,8 +627,14 @@ static struct spi_master * fsl_spi_probe(struct device *dev,
        if (mpc8xxx_spi->type == TYPE_GRLIB)
                fsl_spi_grlib_probe(dev);
 
-       master->bits_per_word_mask =
-               (SPI_BPW_RANGE_MASK(4, 16) | SPI_BPW_MASK(32)) &
+       if (mpc8xxx_spi->flags & SPI_CPM_MODE)
+               master->bits_per_word_mask =
+                       (SPI_BPW_RANGE_MASK(4, 8) | SPI_BPW_MASK(16) | SPI_BPW_MASK(32));
+       else
+               master->bits_per_word_mask =
+                       (SPI_BPW_RANGE_MASK(4, 16) | SPI_BPW_MASK(32));
+
+       master->bits_per_word_mask &=
                SPI_BPW_RANGE_MASK(1, mpc8xxx_spi->max_bits_per_word);
 
        if (mpc8xxx_spi->flags & SPI_QE_CPU_MODE)