[PATCH v2 2/5] spi: spi-gpio: support different word widths

[Sascha Hauer]

The spi-gpio driver only supports 8bit word width. Add support for
arbitrary word widths up to 32bit.

Reviewed-by: Ahmad Fatoum <a.fat...@pengutronix.de>
Signed-off-by: Sascha Hauer <s.ha...@pengutronix.de>
---
 drivers/spi/gpio_spi.c | 57 ++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 48 insertions(+), 9 deletions(-)

diff --git a/drivers/spi/gpio_spi.c b/drivers/spi/gpio_spi.c
index dc9f46ca45..d23abf3dfb 100644
--- a/drivers/spi/gpio_spi.c
+++ b/drivers/spi/gpio_spi.c
@@ -78,7 +78,7 @@ static inline u32 gpio_spi_txrx_word(struct spi_device *spi, 
unsigned nsecs,
                return bitbang_txrx_be_cpha0(spi, nsecs, cpol, word, bits);
 }
 
-static int gpio_spi_transfer_one(struct spi_device *spi, struct spi_transfer 
*t)
+static int gpio_spi_transfer_one_u8(struct spi_device *spi, struct 
spi_transfer *t)
 {
        bool read = (t->rx_buf) ? true : false;
        u32 word = 0;
@@ -87,14 +87,59 @@ static int gpio_spi_transfer_one(struct spi_device *spi, 
struct spi_transfer *t)
        for (n = 0; n < t->len; n++) {
                if (!read)
                        word = ((const u8 *)t->tx_buf)[n];
-               word = gpio_spi_txrx_word(spi, 0, word, 8);
+               word = gpio_spi_txrx_word(spi, 0, word, spi->bits_per_word);
+               if (read)
+                       ((u8 *)t->rx_buf)[n] = word;
+       }
+
+       return 0;
+}
+
+static int gpio_spi_transfer_one_u16(struct spi_device *spi, struct 
spi_transfer *t)
+{
+       bool read = (t->rx_buf) ? true : false;
+       u32 word = 0;
+       int n;
+
+       for (n = 0; n < t->len / 2; n++) {
+               if (!read)
+                       word = ((const u16 *)t->tx_buf)[n];
+               word = gpio_spi_txrx_word(spi, 0, word, spi->bits_per_word);
                if (read)
-                       ((u8 *)t->rx_buf)[n] = word & 0xff;
+                       ((u16 *)t->rx_buf)[n] = word;
        }
 
        return 0;
 }
 
+static int gpio_spi_transfer_one_u32(struct spi_device *spi, struct 
spi_transfer *t)
+{
+       bool read = (t->rx_buf) ? true : false;
+       u32 word = 0;
+       int n;
+
+       for (n = 0; n < t->len / 4; n++) {
+               if (!read)
+                       word = ((const u32 *)t->tx_buf)[n];
+               word = gpio_spi_txrx_word(spi, 0, word, spi->bits_per_word);
+               if (read)
+                       ((u32 *)t->rx_buf)[n] = word;
+       }
+
+       return 0;
+}
+
+static int gpio_spi_transfer_one(struct spi_device *spi, struct spi_transfer 
*t)
+{
+       if (spi->bits_per_word <= 8)
+               return gpio_spi_transfer_one_u8(spi, t);
+       if (spi->bits_per_word <= 16)
+               return gpio_spi_transfer_one_u16(spi, t);
+       if (spi->bits_per_word <= 32)
+               return gpio_spi_transfer_one_u32(spi, t);
+       return -EINVAL;
+}
+
 static int gpio_spi_transfer(struct spi_device *spi, struct spi_message *msg)
 {
        struct spi_transfer *t;
@@ -120,12 +165,6 @@ static int gpio_spi_transfer(struct spi_device *spi, 
struct spi_message *msg)
 
 static int gpio_spi_setup(struct spi_device *spi)
 {
-       if (spi->bits_per_word != 8) {
-               dev_err(spi->master->dev, "master does not support %d bits per 
word\n",
-                       spi->bits_per_word);
-               return -EINVAL;
-       }
-
        return 0;
 }
 

-- 
2.39.5