Initial import

1 files changed, 181 insertions, 0 deletions

diff --git a/drivers/hwmon/lm70.c b/drivers/hwmon/lm70.c
new file mode 100644
index 000000000..97204dce1
--- /dev/null
+++ b/drivers/hwmon/lm70.c
@@ -0,0 +1,181 @@
+/*
+ * 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.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#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/mutex.h>
+#include <linux/mod_devicetable.h>
+#include <linux/spi/spi.h>
+#include <linux/slab.h>
+
+
+#define DRVNAME		"lm70"
+
+#define LM70_CHIP_LM70		0	/* original NS LM70 */
+#define LM70_CHIP_TMP121	1	/* TI TMP121/TMP123 */
+#define LM70_CHIP_LM71		2	/* NS LM71 */
+#define LM70_CHIP_LM74		3	/* NS LM74 */
+
+struct lm70 {
+	struct spi_device *spi;
+	struct mutex lock;
+	unsigned int chip;
+};
+
+/* sysfs hook function */
+static ssize_t lm70_sense_temp(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct lm70 *p_lm70 = dev_get_drvdata(dev);
+	struct spi_device *spi = p_lm70->spi;
+	int status, val = 0;
+	u8 rxbuf[2];
+	s16 raw = 0;
+
+	if (mutex_lock_interruptible(&p_lm70->lock))
+		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) {
+		pr_warn("spi_write_then_read failed with status %d\n", status);
+		goto out;
+	}
+	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);
+
+	/*
+	 * LM70:
+	 * 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.
+	 *
+	 * LM74 and TMP121/TMP123:
+	 * 13 bits of 2's complement data, discard LSB 3 bits,
+	 * resolution 0.0625 degrees celsius.
+	 *
+	 * LM71:
+	 * 14 bits of 2's complement data, discard LSB 2 bits,
+	 * resolution 0.0312 degrees celsius.
+	 */
+	switch (p_lm70->chip) {
+	case LM70_CHIP_LM70:
+		val = ((int)raw / 32) * 250;
+		break;
+
+	case LM70_CHIP_TMP121:
+	case LM70_CHIP_LM74:
+		val = ((int)raw / 8) * 625 / 10;
+		break;
+
+	case LM70_CHIP_LM71:
+		val = ((int)raw / 4) * 3125 / 100;
+		break;
+	}
+
+	status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
+out:
+	mutex_unlock(&p_lm70->lock);
+	return status;
+}
+
+static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL);
+
+static struct attribute *lm70_attrs[] = {
+	&dev_attr_temp1_input.attr,
+	NULL
+};
+
+ATTRIBUTE_GROUPS(lm70);
+
+/*----------------------------------------------------------------------*/
+
+static int lm70_probe(struct spi_device *spi)
+{
+	int chip = spi_get_device_id(spi)->driver_data;
+	struct device *hwmon_dev;
+	struct lm70 *p_lm70;
+
+	/* signaling is SPI_MODE_0 */
+	if (spi->mode & (SPI_CPOL | SPI_CPHA))
+		return -EINVAL;
+
+	/* NOTE:  we assume 8-bit words, and convert to 16 bits manually */
+
+	p_lm70 = devm_kzalloc(&spi->dev, sizeof(*p_lm70), GFP_KERNEL);
+	if (!p_lm70)
+		return -ENOMEM;
+
+	mutex_init(&p_lm70->lock);
+	p_lm70->chip = chip;
+	p_lm70->spi = spi;
+
+	hwmon_dev = devm_hwmon_device_register_with_groups(&spi->dev,
+							   spi->modalias,
+							   p_lm70, lm70_groups);
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct spi_device_id lm70_ids[] = {
+	{ "lm70",   LM70_CHIP_LM70 },
+	{ "tmp121", LM70_CHIP_TMP121 },
+	{ "lm71",   LM70_CHIP_LM71 },
+	{ "lm74",   LM70_CHIP_LM74 },
+	{ },
+};
+MODULE_DEVICE_TABLE(spi, lm70_ids);
+
+static struct spi_driver lm70_driver = {
+	.driver = {
+		.name	= "lm70",
+		.owner	= THIS_MODULE,
+	},
+	.id_table = lm70_ids,
+	.probe	= lm70_probe,
+};
+
+module_spi_driver(lm70_driver);
+
+MODULE_AUTHOR("Kaiwan N Billimoria");
+MODULE_DESCRIPTION("NS LM70 and compatibles Linux driver");
+MODULE_LICENSE("GPL");