spi-bcm2708: add 9-bit support using LoSSI mode

diff --git a/drivers/spi/spi-bcm2708.c b/drivers/spi/spi-bcm2708.c
index 088cbaa9508829ad3bef3c81718166e4affe179b..1744c1e925691f02cbfc533d419faf99c99c8c28 100644 (file)
--- a/drivers/spi/spi-bcm2708.c
+++ b/drivers/spi/spi-bcm2708.c
@@ -146,10 +146,31 @@ static inline void bcm2708_rd_fifo(struct bcm2708_spi *bs, int len)
 static inline void bcm2708_wr_fifo(struct bcm2708_spi *bs, int len)
 {
        u8 byte;
+       u16 val;
 
        if (len > bs->len)
                len = bs->len;
 
+       if (unlikely(bcm2708_rd(bs, SPI_CS) & SPI_CS_LEN)) {
+               /* LoSSI mode */
+               if (unlikely(len % 2)) {
+                       printk(KERN_ERR"bcm2708_wr_fifo: length must be even, skipping.\n");
+                       bs->len = 0;
+                       return;
+               }
+               while (len) {
+                       if (bs->tx_buf) {
+                               val = *(const u16 *)bs->tx_buf;
+                               bs->tx_buf += 2;
+                       } else
+                               val = 0;
+                       bcm2708_wr(bs, SPI_FIFO, val);
+                       bs->len -= 2;
+                       len -= 2;
+               }
+               return;
+       }
+
        while (len--) {
                byte = bs->tx_buf ? *bs->tx_buf++ : 0;
                bcm2708_wr(bs, SPI_FIFO, byte);
@@ -234,8 +255,12 @@ static int bcm2708_setup_state(struct spi_master *master,
        switch (bpw) {
        case 8:
                break;
+       case 9:
+               /* Reading in LoSSI mode is a special case. See 'BCM2835 ARM Peripherals' datasheet */
+               cs |= SPI_CS_LEN;
+               break;
        default:
-               dev_dbg(dev, "setup: invalid bits_per_word %u (must be 8)\n",
+               dev_dbg(dev, "setup: invalid bits_per_word %u (must be 8 or 9)\n",
                        bpw);
                return -EINVAL;
        }
@@ -283,7 +308,8 @@ static int bcm2708_process_transfer(struct bcm2708_spi *bs,
                ret = bcm2708_setup_state(spi->master, &spi->dev, &state,
                        xfer->speed_hz ? xfer->speed_hz : spi->max_speed_hz,
                        spi->chip_select, spi->mode,
-                       spi->bits_per_word);
+                       xfer->bits_per_word ? xfer->bits_per_word :
+                               spi->bits_per_word);
                if (ret)
                        return ret;