path: root/include
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authorImre Deak <imre.deak@nokia.com>2006-02-17 10:02:18 -0800
committerGreg Kroah-Hartman <gregkh@suse.de>2006-05-16 14:33:56 -0700
commit4cff33f94fefcce1b3c01a9d1da6bb85fe3cbdfa (patch)
tree0ef6066c4f2c0225517a6402bb04f4b4d56afd4d /include
parent716f8954fb3029ca2df52a986b60af8d06f093ee (diff)
[PATCH] SPI: per-transfer overrides for wordsize and clocking
Some protocols (like one for some bitmap displays) require different clock speed or word size settings for each transfer in an SPI message. This adds those parameters to struct spi_transfer. They are to be used when they are nonzero; otherwise the defaults from spi_device are to be used. The patch also adds a setup_transfer callback to spi_bitbang, uses it for messages that use those overrides, and implements it so that the pure bitbanging code can help resolve any questions about how it should work. Signed-off-by: Imre Deak <imre.deak@nokia.com> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'include')
2 files changed, 14 insertions, 0 deletions
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index b05f1463a26..caa4665e3fa 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -31,6 +31,7 @@ extern struct bus_type spi_bus_type;
* @master: SPI controller used with the device.
* @max_speed_hz: Maximum clock rate to be used with this chip
* (on this board); may be changed by the device's driver.
+ * The spi_transfer.speed_hz can override this for each transfer.
* @chip-select: Chipselect, distinguishing chips handled by "master".
* @mode: The spi mode defines how data is clocked out and in.
* This may be changed by the device's driver.
@@ -38,6 +39,7 @@ extern struct bus_type spi_bus_type;
* like eight or 12 bits are common. In-memory wordsizes are
* powers of two bytes (e.g. 20 bit samples use 32 bits).
* This may be changed by the device's driver.
+ * The spi_transfer.bits_per_word can override this for each transfer.
* @irq: Negative, or the number passed to request_irq() to receive
* interrupts from this device.
* @controller_state: Controller's runtime state
@@ -268,6 +270,10 @@ extern struct spi_master *spi_busnum_to_master(u16 busnum);
* @tx_dma: DMA address of tx_buf, if spi_message.is_dma_mapped
* @rx_dma: DMA address of rx_buf, if spi_message.is_dma_mapped
* @len: size of rx and tx buffers (in bytes)
+ * @speed_hz: Select a speed other then the device default for this
+ * transfer. If 0 the default (from spi_device) is used.
+ * @bits_per_word: select a bits_per_word other then the device default
+ * for this transfer. If 0 the default (from spi_device) is used.
* @cs_change: affects chipselect after this transfer completes
* @delay_usecs: microseconds to delay after this transfer before
* (optionally) changing the chipselect status, then starting
@@ -322,7 +328,9 @@ struct spi_transfer {
dma_addr_t rx_dma;
unsigned cs_change:1;
+ u8 bits_per_word;
u16 delay_usecs;
+ u32 speed_hz;
struct list_head transfer_list;
diff --git a/include/linux/spi/spi_bitbang.h b/include/linux/spi/spi_bitbang.h
index c961fe9bf3e..c954557b757 100644
--- a/include/linux/spi/spi_bitbang.h
+++ b/include/linux/spi/spi_bitbang.h
@@ -30,6 +30,12 @@ struct spi_bitbang {
struct spi_master *master;
+ /* setup_transfer() changes clock and/or wordsize to match settings
+ * for this transfer; zeroes restore defaults from spi_device.
+ */
+ int (*setup_transfer)(struct spi_device *spi,
+ struct spi_transfer *t);
void (*chipselect)(struct spi_device *spi, int is_on);
#define BITBANG_CS_ACTIVE 1 /* normally nCS, active low */