From c06e677aed0c86480b01faa894967daa8aa3568a Mon Sep 17 00:00:00 2001
From: David Brownell <david-b@pacbell.net>
Date: Tue, 17 Jul 2007 04:04:03 -0700
Subject: [PATCH] SPI: add 3wire mode flag
Add a new spi->mode bit: SPI_3WIRE, for chips where the SI and SO signals
are shared (and which are thus only half duplex). Update the LM70 driver
to require support for that hardware mode from the controller.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
drivers/hwmon/lm70.c | 4 ++++
include/linux/spi/spi.h | 1 +
2 files changed, 5 insertions(+)
diff --git a/drivers/hwmon/lm70.c b/drivers/hwmon/lm70.c
index 7eaae3834e157..275d392eca611 100644
--- a/drivers/hwmon/lm70.c
+++ b/drivers/hwmon/lm70.c
@@ -96,6 +96,10 @@ static int __devinit lm70_probe(struct spi_device *spi)
struct lm70 *p_lm70;
int status;
+ /* signaling is SPI_MODE_0 on a 3-wire link (shared SI/SO) */
+ if ((spi->mode & (SPI_CPOL|SPI_CPHA)) || !(spi->mode & SPI_3WIRE))
+ return -EINVAL;
+
p_lm70 = kzalloc(sizeof *p_lm70, GFP_KERNEL);
if (!p_lm70)
return -ENOMEM;
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 1be5ea0594771..302b81d1d1176 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -76,6 +76,7 @@ struct spi_device {
#define SPI_MODE_3 (SPI_CPOL|SPI_CPHA)
#define SPI_CS_HIGH 0x04 /* chipselect active high? */
#define SPI_LSB_FIRST 0x08 /* per-word bits-on-wire */
+#define SPI_3WIRE 0x10 /* SI/SO signals shared */
u8 bits_per_word;
int irq;
void *controller_state;
--
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