--- /dev/null
+/*
+ * 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");
Code Review / kvmfornfv.git / blobdiff