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The TMP125 is a 2 degree Celsius accurate Digital Temperature Sensor with a SPI interface. The temperature register is a 16-bit, read-only register. The MSB (Bit 15) is a leading zero and never set. Bits 14 to 5 are the 1+9 temperature data bits in a two's complement format. Bits 4 to 0 are useless copies of Bit 5 value and therefore ignored. This was tested on a Aerohive HiveAP-350. Bonus: lm70 supports TMP122/TMP124 as well. I added them to the Kconfig module description. Signed-off-by: Christian Lamparter <chunkeey@gmail.com> Link: https://lore.kernel.org/r/43b19cbd4e7f51e9509e561b02b5d8d0e7079fac.1645175187.git.chunkeey@gmail.com Signed-off-by: Guenter Roeck <linux@roeck-us.net>
223 lines
5.4 KiB
C
223 lines
5.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* lm70.c
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*
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* The LM70 is a temperature sensor chip from National Semiconductor (NS).
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* Copyright (C) 2006 Kaiwan N Billimoria <kaiwan@designergraphix.com>
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*
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* The LM70 communicates with a host processor via an SPI/Microwire Bus
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* interface. The complete datasheet is available at National's website
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* here:
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* http://www.national.com/pf/LM/LM70.html
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/sysfs.h>
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#include <linux/hwmon.h>
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#include <linux/mutex.h>
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#include <linux/mod_devicetable.h>
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#include <linux/of.h>
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#include <linux/property.h>
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#include <linux/spi/spi.h>
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#include <linux/slab.h>
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#define DRVNAME "lm70"
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#define LM70_CHIP_LM70 0 /* original NS LM70 */
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#define LM70_CHIP_TMP121 1 /* TI TMP121/TMP123 */
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#define LM70_CHIP_LM71 2 /* NS LM71 */
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#define LM70_CHIP_LM74 3 /* NS LM74 */
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#define LM70_CHIP_TMP122 4 /* TI TMP122/TMP124 */
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#define LM70_CHIP_TMP125 5 /* TI TMP125 */
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struct lm70 {
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struct spi_device *spi;
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struct mutex lock;
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unsigned int chip;
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};
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/* sysfs hook function */
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static ssize_t temp1_input_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct lm70 *p_lm70 = dev_get_drvdata(dev);
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struct spi_device *spi = p_lm70->spi;
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int status, val = 0;
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u8 rxbuf[2];
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s16 raw = 0;
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if (mutex_lock_interruptible(&p_lm70->lock))
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return -ERESTARTSYS;
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/*
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* spi_read() requires a DMA-safe buffer; so we use
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* spi_write_then_read(), transmitting 0 bytes.
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*/
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status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2);
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if (status < 0) {
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dev_warn(dev, "spi_write_then_read failed with status %d\n",
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status);
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goto out;
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}
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raw = (rxbuf[0] << 8) + rxbuf[1];
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dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n",
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rxbuf[0], rxbuf[1], raw);
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/*
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* LM70:
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* The "raw" temperature read into rxbuf[] is a 16-bit signed 2's
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* complement value. Only the MSB 11 bits (1 sign + 10 temperature
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* bits) are meaningful; the LSB 5 bits are to be discarded.
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* See the datasheet.
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*
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* Further, each bit represents 0.25 degrees Celsius; so, multiply
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* by 0.25. Also multiply by 1000 to represent in millidegrees
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* Celsius.
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* So it's equivalent to multiplying by 0.25 * 1000 = 250.
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*
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* LM74 and TMP121/TMP122/TMP123/TMP124:
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* 13 bits of 2's complement data, discard LSB 3 bits,
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* resolution 0.0625 degrees celsius.
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*
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* LM71:
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* 14 bits of 2's complement data, discard LSB 2 bits,
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* resolution 0.0312 degrees celsius.
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*
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* TMP125:
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* MSB/D15 is a leading zero. D14 is the sign-bit. This is
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* followed by 9 temperature bits (D13..D5) in 2's complement
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* data format with a resolution of 0.25 degrees celsius per unit.
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* LSB 5 bits (D4..D0) share the same value as D5 and get discarded.
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*/
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switch (p_lm70->chip) {
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case LM70_CHIP_LM70:
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val = ((int)raw / 32) * 250;
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break;
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case LM70_CHIP_TMP121:
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case LM70_CHIP_TMP122:
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case LM70_CHIP_LM74:
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val = ((int)raw / 8) * 625 / 10;
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break;
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case LM70_CHIP_LM71:
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val = ((int)raw / 4) * 3125 / 100;
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break;
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case LM70_CHIP_TMP125:
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val = (sign_extend32(raw, 14) / 32) * 250;
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break;
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}
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status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
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out:
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mutex_unlock(&p_lm70->lock);
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return status;
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}
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static DEVICE_ATTR_RO(temp1_input);
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static struct attribute *lm70_attrs[] = {
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&dev_attr_temp1_input.attr,
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NULL
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};
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ATTRIBUTE_GROUPS(lm70);
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/*----------------------------------------------------------------------*/
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#ifdef CONFIG_OF
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static const struct of_device_id lm70_of_ids[] = {
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{
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.compatible = "ti,lm70",
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.data = (void *) LM70_CHIP_LM70,
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},
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{
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.compatible = "ti,tmp121",
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.data = (void *) LM70_CHIP_TMP121,
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},
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{
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.compatible = "ti,tmp122",
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.data = (void *) LM70_CHIP_TMP122,
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},
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{
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.compatible = "ti,tmp125",
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.data = (void *) LM70_CHIP_TMP125,
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},
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{
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.compatible = "ti,lm71",
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.data = (void *) LM70_CHIP_LM71,
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},
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{
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.compatible = "ti,lm74",
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.data = (void *) LM70_CHIP_LM74,
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},
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{},
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};
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MODULE_DEVICE_TABLE(of, lm70_of_ids);
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#endif
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static int lm70_probe(struct spi_device *spi)
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{
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struct device *hwmon_dev;
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struct lm70 *p_lm70;
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int chip;
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if (dev_fwnode(&spi->dev))
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chip = (int)(uintptr_t)device_get_match_data(&spi->dev);
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else
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chip = spi_get_device_id(spi)->driver_data;
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/* signaling is SPI_MODE_0 */
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if ((spi->mode & SPI_MODE_X_MASK) != SPI_MODE_0)
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return -EINVAL;
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/* NOTE: we assume 8-bit words, and convert to 16 bits manually */
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p_lm70 = devm_kzalloc(&spi->dev, sizeof(*p_lm70), GFP_KERNEL);
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if (!p_lm70)
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return -ENOMEM;
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mutex_init(&p_lm70->lock);
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p_lm70->chip = chip;
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p_lm70->spi = spi;
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hwmon_dev = devm_hwmon_device_register_with_groups(&spi->dev,
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spi->modalias,
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p_lm70, lm70_groups);
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return PTR_ERR_OR_ZERO(hwmon_dev);
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}
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static const struct spi_device_id lm70_ids[] = {
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{ "lm70", LM70_CHIP_LM70 },
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{ "tmp121", LM70_CHIP_TMP121 },
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{ "tmp122", LM70_CHIP_TMP122 },
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{ "tmp125", LM70_CHIP_TMP125 },
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{ "lm71", LM70_CHIP_LM71 },
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{ "lm74", LM70_CHIP_LM74 },
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{ },
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};
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MODULE_DEVICE_TABLE(spi, lm70_ids);
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static struct spi_driver lm70_driver = {
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.driver = {
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.name = "lm70",
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.of_match_table = of_match_ptr(lm70_of_ids),
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},
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.id_table = lm70_ids,
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.probe = lm70_probe,
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};
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module_spi_driver(lm70_driver);
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MODULE_AUTHOR("Kaiwan N Billimoria");
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MODULE_DESCRIPTION("NS LM70 and compatibles Linux driver");
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MODULE_LICENSE("GPL");
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