// SPDX-License-Identifier: GPL-2.0-or-later /* * 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 */ #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> #include <linux/of_device.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 */ #define LM70_CHIP_TMP122 4 /* TI TMP122/TMP124 */ struct lm70 { struct spi_device *spi; struct mutex lock; unsigned int chip; }; /* sysfs hook function */ static ssize_t temp1_input_show(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) { dev_warn(dev, "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/TMP122/TMP123/TMP124: * 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_TMP122: 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_RO(temp1_input); static struct attribute *lm70_attrs[] = { &dev_attr_temp1_input.attr, NULL }; ATTRIBUTE_GROUPS(lm70); /*----------------------------------------------------------------------*/ #ifdef CONFIG_OF static const struct of_device_id lm70_of_ids[] = { { .compatible = "ti,lm70", .data = (void *) LM70_CHIP_LM70, }, { .compatible = "ti,tmp121", .data = (void *) LM70_CHIP_TMP121, }, { .compatible = "ti,tmp122", .data = (void *) LM70_CHIP_TMP122, }, { .compatible = "ti,lm71", .data = (void *) LM70_CHIP_LM71, }, { .compatible = "ti,lm74", .data = (void *) LM70_CHIP_LM74, }, {}, }; MODULE_DEVICE_TABLE(of, lm70_of_ids); #endif static int lm70_probe(struct spi_device *spi) { const struct of_device_id *match; struct device *hwmon_dev; struct lm70 *p_lm70; int chip; match = of_match_device(lm70_of_ids, &spi->dev); if (match) chip = (int)(uintptr_t)match->data; else chip = spi_get_device_id(spi)->driver_data; /* 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 }, { "tmp122", LM70_CHIP_TMP122 }, { "lm71", LM70_CHIP_LM71 }, { "lm74", LM70_CHIP_LM74 }, { }, }; MODULE_DEVICE_TABLE(spi, lm70_ids); static struct spi_driver lm70_driver = { .driver = { .name = "lm70", .of_match_table = of_match_ptr(lm70_of_ids), }, .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");