target/linux/brcm2708/patches-3.10/0056-spi-bcm2708-add-9-bit-support-using-LoSSI-mode.patch

   1 From 4b64ce34aaf88c2869c74efad7cbe5167920625b Mon Sep 17 00:00:00 2001
   2 From: notro <notro@tronnes.org>
   3 Date: Sat, 26 Jan 2013 20:38:03 +0100
   4 Subject: [PATCH 056/196] spi-bcm2708: add 9-bit support using LoSSI mode
   5
   6 ---
   7  drivers/spi/spi-bcm2708.c | 30 ++++++++++++++++++++++++++++--
   8  1 file changed, 28 insertions(+), 2 deletions(-)
   9
  10 diff --git a/drivers/spi/spi-bcm2708.c b/drivers/spi/spi-bcm2708.c
  11 index b74aa32..abaa5a6 100644
  12 --- a/drivers/spi/spi-bcm2708.c
  13 +++ b/drivers/spi/spi-bcm2708.c
  14 @@ -146,10 +146,31 @@ static inline void bcm2708_rd_fifo(struct bcm2708_spi *bs, int len)
  15  static inline void bcm2708_wr_fifo(struct bcm2708_spi *bs, int len)
  16  {
  17         u8 byte;
  18 +       u16 val;
  19
  20         if (len > bs->len)
  21                 len = bs->len;
  22
  23 +       if (unlikely(bcm2708_rd(bs, SPI_CS) & SPI_CS_LEN)) {
  24 +               /* LoSSI mode */
  25 +               if (unlikely(len % 2)) {
  26 +                       printk(KERN_ERR"bcm2708_wr_fifo: length must be even, skipping.\n");
  27 +                       bs->len = 0;
  28 +                       return;
  29 +               }
  30 +               while (len) {
  31 +                       if (bs->tx_buf) {
  32 +                               val = *(const u16 *)bs->tx_buf;
  33 +                               bs->tx_buf += 2;
  34 +                       } else
  35 +                               val = 0;
  36 +                       bcm2708_wr(bs, SPI_FIFO, val);
  37 +                       bs->len -= 2;
  38 +                       len -= 2;
  39 +               }
  40 +               return;
  41 +       }
  42 +
  43         while (len--) {
  44                 byte = bs->tx_buf ? *bs->tx_buf++ : 0;
  45                 bcm2708_wr(bs, SPI_FIFO, byte);
  46 @@ -234,8 +255,12 @@ static int bcm2708_setup_state(struct spi_master *master,
  47         switch (bpw) {
  48         case 8:
  49                 break;
  50 +       case 9:
  51 +               /* Reading in LoSSI mode is a special case. See 'BCM2835 ARM Peripherals' datasheet */
  52 +               cs |= SPI_CS_LEN;
  53 +               break;
  54         default:
  55 -               dev_dbg(dev, "setup: invalid bits_per_word %u (must be 8)\n",
  56 +               dev_dbg(dev, "setup: invalid bits_per_word %u (must be 8 or 9)\n",
  57                         bpw);
  58                 return -EINVAL;
  59         }
  60 @@ -283,7 +308,8 @@ static int bcm2708_process_transfer(struct bcm2708_spi *bs,
  61                 ret = bcm2708_setup_state(spi->master, &spi->dev, &state,
  62                         xfer->speed_hz ? xfer->speed_hz : spi->max_speed_hz,
  63                         spi->chip_select, spi->mode,
  64 -                       spi->bits_per_word);
  65 +                       xfer->bits_per_word ? xfer->bits_per_word :
  66 +                               spi->bits_per_word);
  67                 if (ret)
  68                         return ret;
  69
  70 --
  71 1.9.1
  72