hwmon: (lm70) Code streamlining and cleanup
This fixes a byteswap bug in the LM70 temperature sensor driver,
which was previously covered up by a converse bug in the driver
for the LM70EVAL-LLP board (which is also fixed).
Other fixes: doc updates, remove an annoying msleep(), and improve
three-wire protocol handling.
Signed-off-by: Kaiwan N Billimoria <kaiwan@designergraphix.com>
[ dbrownell@users.sourceforge.net: doc and whitespace tweaks ]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
diff --git a/drivers/spi/spi_lm70llp.c b/drivers/spi/spi_lm70llp.c
index af65267..568c781 100644
--- a/drivers/spi/spi_lm70llp.c
+++ b/drivers/spi/spi_lm70llp.c
@@ -1,5 +1,5 @@
/*
- * spi_lm70llp.c - driver for lm70llp eval board for the LM70 sensor
+ * spi_lm70llp.c - driver for LM70EVAL-LLP board for the LM70 sensor
*
* Copyright (C) 2006 Kaiwan N Billimoria <kaiwan@designergraphix.com>
*
@@ -40,8 +40,12 @@
* master controller driver. The hwmon/lm70 driver is a "SPI protocol
* driver", layered on top of this one and usable without the lm70llp.
*
+ * Datasheet and Schematic:
* The LM70 is a temperature sensor chip from National Semiconductor; its
* datasheet is available at http://www.national.com/pf/LM/LM70.html
+ * The schematic for this particular board (the LM70EVAL-LLP) is
+ * available (on page 4) here:
+ * http://www.national.com/appinfo/tempsensors/files/LM70LLPEVALmanual.pdf
*
* Also see Documentation/spi/spi-lm70llp. The SPI<->parport code here is
* (heavily) based on spi-butterfly by David Brownell.
@@ -64,7 +68,7 @@
*
* Note that parport pin 13 actually gets inverted by the transistor
* arrangement which lets either the parport or the LM70 drive the
- * SI/SO signal.
+ * SI/SO signal (see the schematic for details).
*/
#define DRVNAME "spi-lm70llp"
@@ -106,12 +110,16 @@
static inline void deassertCS(struct spi_lm70llp *pp)
{
u8 data = parport_read_data(pp->port);
+
+ data &= ~0x80; /* pull D7/SI-out low while de-asserted */
parport_write_data(pp->port, data | nCS);
}
static inline void assertCS(struct spi_lm70llp *pp)
{
u8 data = parport_read_data(pp->port);
+
+ data |= 0x80; /* pull D7/SI-out high so lm70 drives SO-in */
parport_write_data(pp->port, data & ~nCS);
}
@@ -184,22 +192,7 @@
*/
static u32 lm70_txrx(struct spi_device *spi, unsigned nsecs, u32 word, u8 bits)
{
- static u32 sio=0;
- static int first_time=1;
-
- /* First time: perform SPI bitbang and return the LSB of
- * the result of the SPI call.
- */
- if (first_time) {
- sio = bitbang_txrx_be_cpha0(spi, nsecs, 0, word, bits);
- first_time=0;
- return (sio & 0x00ff);
- }
- /* Return the MSB of the result of the SPI call */
- else {
- first_time=1;
- return (sio >> 8);
- }
+ return bitbang_txrx_be_cpha0(spi, nsecs, 0, word, bits);
}
static void spi_lm70llp_attach(struct parport *p)
@@ -293,10 +286,9 @@
status = -ENODEV;
goto out_bitbang_stop;
}
- pp->spidev_lm70->bits_per_word = 16;
+ pp->spidev_lm70->bits_per_word = 8;
lm70llp = pp;
-
return;
out_bitbang_stop:
@@ -326,7 +318,6 @@
/* power down */
parport_write_data(pp->port, 0);
- msleep(10);
parport_release(pp->pd);
parport_unregister_device(pp->pd);