target/linux/brcm63xx/patches-4.4/000-4.9-01-spi-introduce-max_message_size-hook-in-spi_master.patch

   1 From 5090cc6ae2f79ee779e5faf7c8a28edf42b7d738 Mon Sep 17 00:00:00 2001
   2 From: Heiner Kallweit <hkallweit1@gmail.com>
   3 Date: Wed, 17 Aug 2016 21:08:01 +0200
   4 Subject: [PATCH] spi: introduce max_message_size hook in spi_master
   5
   6 Recently a maximum transfer size was was introduced in struct spi_master.
   7 However there are also spi controllers with a maximum message size, e.g.
   8 fsl-espi has a max message size of 64KB.
   9 Introduce a hook max_message_size to deal with such limitations.
  10
  11 Also make sure that spi_max_transfer_size doesn't return greater values
  12 than spi_max_message_size, even if hook max_transfer_size is not set.
  13
  14 Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
  15 Signed-off-by: Mark Brown <broonie@kernel.org>
  16 ---
  17  include/linux/spi/spi.h | 25 +++++++++++++++++++++----
  18  1 file changed, 21 insertions(+), 4 deletions(-)
  19
  20 --- a/include/linux/spi/spi.h
  21 +++ b/include/linux/spi/spi.h
  22 @@ -304,6 +304,8 @@ static inline void spi_unregister_driver
  23   * @min_speed_hz: Lowest supported transfer speed
  24   * @max_speed_hz: Highest supported transfer speed
  25   * @flags: other constraints relevant to this driver
  26 + * @max_message_size: function that returns the max message size for
  27 + *     a &spi_device; may be %NULL, so the default %SIZE_MAX will be used.
  28   * @bus_lock_spinlock: spinlock for SPI bus locking
  29   * @bus_lock_mutex: mutex for SPI bus locking
  30   * @bus_lock_flag: indicates that the SPI bus is locked for exclusive use
  31 @@ -429,10 +431,11 @@ struct spi_master {
  32  #define SPI_MASTER_MUST_TX      BIT(4)         /* requires tx */
  33
  34         /*
  35 -        * on some hardware transfer size may be constrained
  36 +        * on some hardware transfer / message size may be constrained
  37          * the limit may depend on device transfer settings
  38          */
  39         size_t (*max_transfer_size)(struct spi_device *spi);
  40 +       size_t (*max_message_size)(struct spi_device *spi);
  41
  42         /* lock and mutex for SPI bus locking */
  43         spinlock_t              bus_lock_spinlock;
  44 @@ -844,12 +847,26 @@ extern int spi_async_locked(struct spi_d
  45                             struct spi_message *message);
  46
  47  static inline size_t
  48 -spi_max_transfer_size(struct spi_device *spi)
  49 +spi_max_message_size(struct spi_device *spi)
  50  {
  51         struct spi_master *master = spi->master;
  52 -       if (!master->max_transfer_size)
  53 +       if (!master->max_message_size)
  54                 return SIZE_MAX;
  55 -       return master->max_transfer_size(spi);
  56 +       return master->max_message_size(spi);
  57 +}
  58 +
  59 +static inline size_t
  60 +spi_max_transfer_size(struct spi_device *spi)
  61 +{
  62 +       struct spi_master *master = spi->master;
  63 +       size_t tr_max = SIZE_MAX;
  64 +       size_t msg_max = spi_max_message_size(spi);
  65 +
  66 +       if (master->max_transfer_size)
  67 +               tr_max = master->max_transfer_size(spi);
  68 +
  69 +       /* transfer size limit must not be greater than messsage size limit */
  70 +       return min(tr_max, msg_max);
  71  }
  72
  73  /*---------------------------------------------------------------------------*/