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74 lines
2.7 KiB
Diff
74 lines
2.7 KiB
Diff
From 5090cc6ae2f79ee779e5faf7c8a28edf42b7d738 Mon Sep 17 00:00:00 2001
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From: Heiner Kallweit <hkallweit1@gmail.com>
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Date: Wed, 17 Aug 2016 21:08:01 +0200
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Subject: [PATCH] spi: introduce max_message_size hook in spi_master
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Recently a maximum transfer size was was introduced in struct spi_master.
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However there are also spi controllers with a maximum message size, e.g.
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fsl-espi has a max message size of 64KB.
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Introduce a hook max_message_size to deal with such limitations.
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Also make sure that spi_max_transfer_size doesn't return greater values
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than spi_max_message_size, even if hook max_transfer_size is not set.
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Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
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Signed-off-by: Mark Brown <broonie@kernel.org>
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---
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include/linux/spi/spi.h | 25 +++++++++++++++++++++----
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1 file changed, 21 insertions(+), 4 deletions(-)
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--- a/include/linux/spi/spi.h
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+++ b/include/linux/spi/spi.h
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@@ -304,6 +304,8 @@ static inline void spi_unregister_driver
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* @min_speed_hz: Lowest supported transfer speed
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* @max_speed_hz: Highest supported transfer speed
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* @flags: other constraints relevant to this driver
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+ * @max_message_size: function that returns the max message size for
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+ * a &spi_device; may be %NULL, so the default %SIZE_MAX will be used.
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* @bus_lock_spinlock: spinlock for SPI bus locking
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* @bus_lock_mutex: mutex for SPI bus locking
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* @bus_lock_flag: indicates that the SPI bus is locked for exclusive use
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@@ -429,10 +431,11 @@ struct spi_master {
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#define SPI_MASTER_MUST_TX BIT(4) /* requires tx */
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/*
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- * on some hardware transfer size may be constrained
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+ * on some hardware transfer / message size may be constrained
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* the limit may depend on device transfer settings
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*/
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size_t (*max_transfer_size)(struct spi_device *spi);
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+ size_t (*max_message_size)(struct spi_device *spi);
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/* lock and mutex for SPI bus locking */
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spinlock_t bus_lock_spinlock;
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@@ -844,12 +847,26 @@ extern int spi_async_locked(struct spi_d
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struct spi_message *message);
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static inline size_t
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-spi_max_transfer_size(struct spi_device *spi)
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+spi_max_message_size(struct spi_device *spi)
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{
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struct spi_master *master = spi->master;
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- if (!master->max_transfer_size)
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+ if (!master->max_message_size)
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return SIZE_MAX;
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- return master->max_transfer_size(spi);
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+ return master->max_message_size(spi);
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+}
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+
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+static inline size_t
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+spi_max_transfer_size(struct spi_device *spi)
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+{
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+ struct spi_master *master = spi->master;
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+ size_t tr_max = SIZE_MAX;
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+ size_t msg_max = spi_max_message_size(spi);
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+
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+ if (master->max_transfer_size)
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+ tr_max = master->max_transfer_size(spi);
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+
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+ /* transfer size limit must not be greater than messsage size limit */
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+ return min(tr_max, msg_max);
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}
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/*---------------------------------------------------------------------------*/
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