[PATCH] lm70: New hardware monitoring driver
Kaiwan N Billimoria [Mon, 12 Jun 2006 20:00:05 +0000 (22:00 +0200)]
This driver implements support for the National Semiconductor LM70
temperature sensor.

The LM70 temperature sensor chip supports a single temperature sensor.
It communicates with a host processor (or microcontroller) via an
SPI/Microwire Bus interface.

Communication with the LM70 is simple: when the temperature is to be sensed,
the driver accesses the LM70 using SPI communication: 16 SCLK cycles
comprise the MOSI/MISO loop. At the end of the transfer, the 11-bit 2's
complement digital temperature (sent via the SIO line), is available in the
driver for interpretation. This driver makes use of the kernel's in-core
SPI support.

Signed-off-by: Kaiwan N Billimoria <kaiwan@designergraphix.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

Documentation/hwmon/lm70 [new file with mode: 0644]
drivers/hwmon/Kconfig
drivers/hwmon/Makefile
drivers/hwmon/lm70.c [new file with mode: 0644]

diff --git a/Documentation/hwmon/lm70 b/Documentation/hwmon/lm70
new file mode 100644 (file)
index 0000000..2bdd3fe
--- /dev/null
@@ -0,0 +1,31 @@
+Kernel driver lm70
+==================
+
+Supported chip:
+  * National Semiconductor LM70
+    Datasheet: http://www.national.com/pf/LM/LM70.html
+
+Author:
+        Kaiwan N Billimoria <kaiwan@designergraphix.com>
+
+Description
+-----------
+
+This driver implements support for the National Semiconductor LM70
+temperature sensor.
+
+The LM70 temperature sensor chip supports a single temperature sensor.
+It communicates with a host processor (or microcontroller) via an
+SPI/Microwire Bus interface.
+
+Communication with the LM70 is simple: when the temperature is to be sensed,
+the driver accesses the LM70 using SPI communication: 16 SCLK cycles
+comprise the MOSI/MISO loop. At the end of the transfer, the 11-bit 2's
+complement digital temperature (sent via the SIO line), is available in the
+driver for interpretation. This driver makes use of the kernel's in-core
+SPI support.
+
+Thanks to
+---------
+Jean Delvare <khali@linux-fr.org> for mentoring the hwmon-side driver
+development.
index 43e1f08..0e31a0c 100644 (file)
@@ -204,6 +204,16 @@ config SENSORS_LM63
          This driver can also be built as a module.  If so, the module
          will be called lm63.
 
+config SENSORS_LM70
+       tristate "National Semiconductor LM70"
+       depends on HWMON && SPI_MASTER && EXPERIMENTAL
+       help
+         If you say yes here you get support for the National Semiconductor
+         LM70 digital temperature sensor chip.
+
+         This driver can also be built as a module.  If so, the module
+         will be called lm70.
+
 config SENSORS_LM75
        tristate "National Semiconductor LM75 and compatibles"
        depends on HWMON && I2C
index 5092999..3141584 100644 (file)
@@ -28,6 +28,7 @@ obj-$(CONFIG_SENSORS_GL520SM) += gl520sm.o
 obj-$(CONFIG_SENSORS_HDAPS)    += hdaps.o
 obj-$(CONFIG_SENSORS_IT87)     += it87.o
 obj-$(CONFIG_SENSORS_LM63)     += lm63.o
+obj-$(CONFIG_SENSORS_LM70)     += lm70.o
 obj-$(CONFIG_SENSORS_LM75)     += lm75.o
 obj-$(CONFIG_SENSORS_LM77)     += lm77.o
 obj-$(CONFIG_SENSORS_LM78)     += lm78.o
diff --git a/drivers/hwmon/lm70.c b/drivers/hwmon/lm70.c
new file mode 100644 (file)
index 0000000..6ba8473
--- /dev/null
@@ -0,0 +1,165 @@
+/*
+ * lm70.c
+ *
+ * The LM70 is a temperature sensor chip from National Semiconductor (NS).
+ * Copyright (C) 2006 Kaiwan N Billimoria <kaiwan@designergraphix.com>
+ *
+ * The LM70 communicates with a host processor via an SPI/Microwire Bus
+ * interface. The complete datasheet is available at National's website
+ * here:
+ * http://www.national.com/pf/LM/LM70.html
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/sysfs.h>
+#include <linux/hwmon.h>
+#include <linux/spi/spi.h>
+#include <asm/semaphore.h>
+
+#define DRVNAME                "lm70"
+
+struct lm70 {
+       struct class_device *cdev;
+       struct semaphore sem;
+};
+
+/* sysfs hook function */
+static ssize_t lm70_sense_temp(struct device *dev,
+               struct device_attribute *attr, char *buf)
+{
+       struct spi_device *spi = to_spi_device(dev);
+       int status, val;
+       u8 rxbuf[2];
+       s16 raw=0;
+       struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev);
+
+       if (down_interruptible(&p_lm70->sem))
+               return -ERESTARTSYS;
+
+       /*
+        * spi_read() requires a DMA-safe buffer; so we use
+        * spi_write_then_read(), transmitting 0 bytes.
+        */
+       status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2);
+       if (status < 0) {
+               printk(KERN_WARNING
+               "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);
+
+       /*
+        * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's
+        * complement value. Only the MSB 11 bits (1 sign + 10 temperature
+        * bits) are meaningful; the LSB 5 bits are to be discarded.
+        * See the datasheet.
+        *
+        * Further, each bit represents 0.25 degrees Celsius; so, multiply
+        * by 0.25. Also multiply by 1000 to represent in millidegrees
+        * Celsius.
+        * So it's equivalent to multiplying by 0.25 * 1000 = 250.
+        */
+       val = ((int)raw/32) * 250;
+       status = sprintf(buf, "%+d\n", val); /* millidegrees Celsius */
+out:
+       up(&p_lm70->sem);
+       return status;
+}
+
+static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL);
+
+/*----------------------------------------------------------------------*/
+
+static int __devinit lm70_probe(struct spi_device *spi)
+{
+       struct lm70 *p_lm70;
+       int status;
+
+       p_lm70 = kzalloc(sizeof *p_lm70, GFP_KERNEL);
+       if (!p_lm70)
+               return -ENOMEM;
+
+       init_MUTEX(&p_lm70->sem);
+
+       /* sysfs hook */
+       p_lm70->cdev = hwmon_device_register(&spi->dev);
+       if (IS_ERR(p_lm70->cdev)) {
+               dev_dbg(&spi->dev, "hwmon_device_register failed.\n");
+               status = PTR_ERR(p_lm70->cdev);
+               goto out_dev_reg_failed;
+       }
+       dev_set_drvdata(&spi->dev, p_lm70);
+
+       if ((status = device_create_file(&spi->dev, &dev_attr_temp1_input))) {
+               dev_dbg(&spi->dev, "device_create_file failure.\n");
+               goto out_dev_create_file_failed;
+       }
+
+       return 0;
+
+out_dev_create_file_failed:
+       hwmon_device_unregister(p_lm70->cdev);
+out_dev_reg_failed:
+       dev_set_drvdata(&spi->dev, NULL);
+       kfree(p_lm70);
+       return status;
+}
+
+static int __exit lm70_remove(struct spi_device *spi)
+{
+       struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev);
+
+       device_remove_file(&spi->dev, &dev_attr_temp1_input);
+       hwmon_device_unregister(p_lm70->cdev);
+       dev_set_drvdata(&spi->dev, NULL);
+       kfree(p_lm70);
+
+       return 0;
+}
+
+static struct spi_driver lm70_driver = {
+       .driver = {
+               .name   = "lm70",
+               .owner  = THIS_MODULE,
+       },
+       .probe  = lm70_probe,
+       .remove = __devexit_p(lm70_remove),
+};
+
+static int __init init_lm70(void)
+{
+       return spi_register_driver(&lm70_driver);
+}
+
+static void __exit cleanup_lm70(void)
+{
+       spi_unregister_driver(&lm70_driver);
+}
+
+module_init(init_lm70);
+module_exit(cleanup_lm70);
+
+MODULE_AUTHOR("Kaiwan N Billimoria");
+MODULE_DESCRIPTION("National Semiconductor LM70 Linux driver");
+MODULE_LICENSE("GPL");