The patch titled
spi: new spi->mode bits
has been added to the -mm tree. Its filename is
spi-new-spi-mode-bits.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: spi: new spi->mode bits
From: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
Add two new spi_device.mode bits to accomodate more protocol options, and
pass them through to usermode drivers:
* SPI_NO_CS ... a second 3-wire variant, where the chipselect
line is removed instead of a data line; transfers are still
full duplex.
This obviously has STRONG protocol implications since the
chipselect transitions can't be used to synchronize state
transitions with the SPI master.
* SPI_READY ... defines open drain signal that's pulled low
to pause the clock. This defines a 5-wire variant (normal
4-wire SPI plus READY) and two 4-wire variants (READY plus
each of the 3-wire flavors).
Such hardware flow control can be a big win. There are ADC
converters and flash chips that expose READY signals, but not
many host controllers support it today.
The spi_bitbang code should be changed to use SPI_NO_CS instead of its
current nonportable hack. That's a mode most hardware can easily support
(unlike SPI_READY).
Signed-off-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
Cc: "Paulraj, Sandeep" <s-paulraj@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/spi/spidev_test.c | 10 +++++++++-
drivers/spi/spidev.c | 17 +++++++++++------
include/linux/spi/spi.h | 2 ++
include/linux/spi/spidev.h | 2 ++
4 files changed, 24 insertions(+), 7 deletions(-)
diff -puN Documentation/spi/spidev_test.c~spi-new-spi-mode-bits Documentation/spi/spidev_test.c
--- a/Documentation/spi/spidev_test.c~spi-new-spi-mode-bits
+++ a/Documentation/spi/spidev_test.c
@@ -99,11 +99,13 @@ void parse_opts(int argc, char *argv[])
{ "lsb", 0, 0, 'L' },
{ "cs-high", 0, 0, 'C' },
{ "3wire", 0, 0, '3' },
+ { "no-cs", 0, 0, 'N' },
+ { "ready", 0, 0, 'R' },
{ NULL, 0, 0, 0 },
};
int c;
- c = getopt_long(argc, argv, "D:s:d:b:lHOLC3", lopts, NULL);
+ c = getopt_long(argc, argv, "D:s:d:b:lHOLC3NR", lopts, NULL);
if (c == -1)
break;
@@ -139,6 +141,12 @@ void parse_opts(int argc, char *argv[])
case '3':
mode |= SPI_3WIRE;
break;
+ case 'N':
+ mode |= SPI_NO_CS;
+ break;
+ case 'R':
+ mode |= SPI_READY;
+ break;
default:
print_usage(argv[0]);
break;
diff -puN drivers/spi/spidev.c~spi-new-spi-mode-bits drivers/spi/spidev.c
--- a/drivers/spi/spidev.c~spi-new-spi-mode-bits
+++ a/drivers/spi/spidev.c
@@ -58,15 +58,20 @@ static unsigned long minors[N_SPI_MINORS
/* Bit masks for spi_device.mode management. Note that incorrect
- * settings for CS_HIGH and 3WIRE can cause *lots* of trouble for other
- * devices on a shared bus: CS_HIGH, because this device will be
- * active when it shouldn't be; 3WIRE, because when active it won't
- * behave as it should.
+ * settings for some settings can cause *lots* of trouble for other
+ * devices on a shared bus:
*
- * REVISIT should changing those two modes be privileged?
+ * - CS_HIGH ... this device will be active when it shouldn't be
+ * - 3WIRE ... when active, it won't behave as it should
+ * - NO_CS ... there will be no explicit message boundaries; this
+ * is completely incompatible with the shared bus model
+ * - READY ... transfers may proceed when they shouldn't.
+ *
+ * REVISIT should changing those flags be privileged?
*/
#define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \
- | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP)
+ | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
+ | SPI_NO_CS | SPI_READY)
struct spidev_data {
dev_t devt;
diff -puN include/linux/spi/spi.h~spi-new-spi-mode-bits include/linux/spi/spi.h
--- a/include/linux/spi/spi.h~spi-new-spi-mode-bits
+++ a/include/linux/spi/spi.h
@@ -80,6 +80,8 @@ struct spi_device {
#define SPI_LSB_FIRST 0x08 /* per-word bits-on-wire */
#define SPI_3WIRE 0x10 /* SI/SO signals shared */
#define SPI_LOOP 0x20 /* loopback mode */
+#define SPI_NO_CS 0x40 /* 1 dev/bus, no chipselect */
+#define SPI_READY 0x80 /* slave pulls low to pause */
u8 bits_per_word;
int irq;
void *controller_state;
diff -puN include/linux/spi/spidev.h~spi-new-spi-mode-bits include/linux/spi/spidev.h
--- a/include/linux/spi/spidev.h~spi-new-spi-mode-bits
+++ a/include/linux/spi/spidev.h
@@ -40,6 +40,8 @@
#define SPI_LSB_FIRST 0x08
#define SPI_3WIRE 0x10
#define SPI_LOOP 0x20
+#define SPI_NO_CS 0x40
+#define SPI_READY 0x80
/*---------------------------------------------------------------------------*/
_
Patches currently in -mm which might be from dbrownell@xxxxxxxxxxxxxxxxxxxxx are
origin.patch
spi-new-spi-mode-bits.patch
spi-add-spi_master-flag-word.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
