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

   1 From 75c9b03f90ca974cb072d96f423884b773ca5425 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 056/174] 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 --- a/drivers/spi/spi-bcm2708.c
  11 +++ b/drivers/spi/spi-bcm2708.c
  12 @@ -146,10 +146,31 @@ static inline void bcm2708_rd_fifo(struc
  13  static inline void bcm2708_wr_fifo(struct bcm2708_spi *bs, int len)
  14  {
  15         u8 byte;
  16 +       u16 val;
  17
  18         if (len > bs->len)
  19                 len = bs->len;
  20
  21 +       if (unlikely(bcm2708_rd(bs, SPI_CS) & SPI_CS_LEN)) {
  22 +               /* LoSSI mode */
  23 +               if (unlikely(len % 2)) {
  24 +                       printk(KERN_ERR"bcm2708_wr_fifo: length must be even, skipping.\n");
  25 +                       bs->len = 0;
  26 +                       return;
  27 +               }
  28 +               while (len) {
  29 +                       if (bs->tx_buf) {
  30 +                               val = *(const u16 *)bs->tx_buf;
  31 +                               bs->tx_buf += 2;
  32 +                       } else
  33 +                               val = 0;
  34 +                       bcm2708_wr(bs, SPI_FIFO, val);
  35 +                       bs->len -= 2;
  36 +                       len -= 2;
  37 +               }
  38 +               return;
  39 +       }
  40 +
  41         while (len--) {
  42                 byte = bs->tx_buf ? *bs->tx_buf++ : 0;
  43                 bcm2708_wr(bs, SPI_FIFO, byte);
  44 @@ -234,8 +255,12 @@ static int bcm2708_setup_state(struct sp
  45         switch (bpw) {
  46         case 8:
  47                 break;
  48 +       case 9:
  49 +               /* Reading in LoSSI mode is a special case. See 'BCM2835 ARM Peripherals' datasheet */
  50 +               cs |= SPI_CS_LEN;
  51 +               break;
  52         default:
  53 -               dev_dbg(dev, "setup: invalid bits_per_word %u (must be 8)\n",
  54 +               dev_dbg(dev, "setup: invalid bits_per_word %u (must be 8 or 9)\n",
  55                         bpw);
  56                 return -EINVAL;
  57         }
  58 @@ -283,7 +308,8 @@ static int bcm2708_process_transfer(stru
  59                 ret = bcm2708_setup_state(spi->master, &spi->dev, &state,
  60                         xfer->speed_hz ? xfer->speed_hz : spi->max_speed_hz,
  61                         spi->chip_select, spi->mode,
  62 -                       spi->bits_per_word);
  63 +                       xfer->bits_per_word ? xfer->bits_per_word :
  64 +                               spi->bits_per_word);
  65                 if (ret)
  66                         return ret;
  67