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| author | Heiner Kallweit <hkallweit1@gmail.com> | 2016-08-17 21:08:01 +0200 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2016-08-18 11:14:48 +0100 |
| commit | 5090cc6ae2f79ee779e5faf7c8a28edf42b7d738 (patch) | |
| tree | 531e431fa02f122fbc13ff0d498bc908cc2e3f2b /include/linux/spi | |
| parent | 29b4817d4018df78086157ea3a55c1d9424a7cfc (diff) | |
| download | lwn-5090cc6ae2f79ee779e5faf7c8a28edf42b7d738.tar.gz lwn-5090cc6ae2f79ee779e5faf7c8a28edf42b7d738.zip | |
spi: introduce max_message_size hook in spi_master
Recently a maximum transfer size was was introduced in struct spi_master.
However there are also spi controllers with a maximum message size, e.g.
fsl-espi has a max message size of 64KB.
Introduce a hook max_message_size to deal with such limitations.
Also make sure that spi_max_transfer_size doesn't return greater values
than spi_max_message_size, even if hook max_transfer_size is not set.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'include/linux/spi')
| -rw-r--r-- | include/linux/spi/spi.h | 25 |
1 files changed, 21 insertions, 4 deletions
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 072cb2aa2413..f2d3960cc3c3 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -312,6 +312,8 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv) * @flags: other constraints relevant to this driver * @max_transfer_size: function that returns the max transfer size for * a &spi_device; may be %NULL, so the default %SIZE_MAX will be used. + * @max_message_size: function that returns the max message size for + * a &spi_device; may be %NULL, so the default %SIZE_MAX will be used. * @io_mutex: mutex for physical bus access * @bus_lock_spinlock: spinlock for SPI bus locking * @bus_lock_mutex: mutex for exclusion of multiple callers @@ -442,10 +444,11 @@ struct spi_master { #define SPI_MASTER_MUST_TX BIT(4) /* requires tx */ /* - * on some hardware transfer size may be constrained + * on some hardware transfer / message size may be constrained * the limit may depend on device transfer settings */ size_t (*max_transfer_size)(struct spi_device *spi); + size_t (*max_message_size)(struct spi_device *spi); /* I/O mutex */ struct mutex io_mutex; @@ -905,12 +908,26 @@ extern int spi_async_locked(struct spi_device *spi, struct spi_message *message); static inline size_t -spi_max_transfer_size(struct spi_device *spi) +spi_max_message_size(struct spi_device *spi) { struct spi_master *master = spi->master; - if (!master->max_transfer_size) + if (!master->max_message_size) return SIZE_MAX; - return master->max_transfer_size(spi); + return master->max_message_size(spi); +} + +static inline size_t +spi_max_transfer_size(struct spi_device *spi) +{ + struct spi_master *master = spi->master; + size_t tr_max = SIZE_MAX; + size_t msg_max = spi_max_message_size(spi); + + if (master->max_transfer_size) + tr_max = master->max_transfer_size(spi); + + /* transfer size limit must not be greater than messsage size limit */ + return min(tr_max, msg_max); } /*---------------------------------------------------------------------------*/ |