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/Documentation/hwmon/lm70 b/Documentation/hwmon/lm70
index 2bdd3fe..b8d1a52 100644
--- a/Documentation/hwmon/lm70
+++ b/Documentation/hwmon/lm70
@@ -25,6 +25,10 @@
driver for interpretation. This driver makes use of the kernel's in-core
SPI support.
+As a real (in-tree) example of this "SPI protocol driver" interfacing
+with a "SPI master controller driver", see drivers/spi/spi_lm70llp.c
+and its associated documentation.
+
Thanks to
---------
Jean Delvare <khali@linux-fr.org> for mentoring the hwmon-side driver
diff --git a/Documentation/spi/spi-lm70llp b/Documentation/spi/spi-lm70llp
index 154bd02..34a9cfd 100644
--- a/Documentation/spi/spi-lm70llp
+++ b/Documentation/spi/spi-lm70llp
@@ -13,10 +13,20 @@
This driver provides glue code connecting a National Semiconductor LM70 LLP
temperature sensor evaluation board to the kernel's SPI core subsystem.
+This is a SPI master controller driver. It can be used in conjunction with
+(layered under) the LM70 logical driver (a "SPI protocol driver").
In effect, this driver turns the parallel port interface on the eval board
into a SPI bus with a single device, which will be driven by the generic
LM70 driver (drivers/hwmon/lm70.c).
+
+Hardware Interfacing
+--------------------
+The schematic for this particular board (the LM70EVAL-LLP) is
+available (on page 4) here:
+
+ http://www.national.com/appinfo/tempsensors/files/LM70LLPEVALmanual.pdf
+
The hardware interfacing on the LM70 LLP eval board is as follows:
Parallel LM70 LLP
diff --git a/drivers/hwmon/lm70.c b/drivers/hwmon/lm70.c
index d435f00..9f9741b 100644
--- a/drivers/hwmon/lm70.c
+++ b/drivers/hwmon/lm70.c
@@ -65,10 +65,9 @@
"spi_write_then_read failed with status %d\n", status);
goto out;
}
- dev_dbg(dev, "rxbuf[1] : 0x%x rxbuf[0] : 0x%x\n", rxbuf[1], rxbuf[0]);
-
- raw = (rxbuf[1] << 8) + rxbuf[0];
- dev_dbg(dev, "raw=0x%x\n", raw);
+ raw = (rxbuf[0] << 8) + rxbuf[1];
+ dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n",
+ rxbuf[0], rxbuf[1], raw);
/*
* The "raw" temperature read into rxbuf[] is a 16-bit signed 2's
@@ -109,6 +108,8 @@
if ((spi->mode & (SPI_CPOL|SPI_CPHA)) || !(spi->mode & SPI_3WIRE))
return -EINVAL;
+ /* NOTE: we assume 8-bit words, and convert to 16 bits manually */
+
p_lm70 = kzalloc(sizeof *p_lm70, GFP_KERNEL);
if (!p_lm70)
return -ENOMEM;
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);