1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
|
From 5090cc6ae2f79ee779e5faf7c8a28edf42b7d738 Mon Sep 17 00:00:00 2001
From: Heiner Kallweit <hkallweit1@gmail.com>
Date: Wed, 17 Aug 2016 21:08:01 +0200
Subject: [PATCH] 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>
---
include/linux/spi/spi.h | 25 +++++++++++++++++++++----
1 file changed, 21 insertions(+), 4 deletions(-)
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -304,6 +304,8 @@ static inline void spi_unregister_driver
* @min_speed_hz: Lowest supported transfer speed
* @max_speed_hz: Highest supported transfer speed
* @flags: other constraints relevant to this driver
+ * @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.
* @bus_lock_spinlock: spinlock for SPI bus locking
* @bus_lock_mutex: mutex for SPI bus locking
* @bus_lock_flag: indicates that the SPI bus is locked for exclusive use
@@ -429,10 +431,11 @@ 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);
/* lock and mutex for SPI bus locking */
spinlock_t bus_lock_spinlock;
@@ -844,12 +847,26 @@ extern int spi_async_locked(struct spi_d
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);
}
/*---------------------------------------------------------------------------*/
|
