diff options
Diffstat (limited to 'drivers/hwmon/lm70.c')
| -rw-r--r-- | drivers/hwmon/lm70.c | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/drivers/hwmon/lm70.c b/drivers/hwmon/lm70.c new file mode 100644 index 000000000..c20a749fc --- /dev/null +++ b/drivers/hwmon/lm70.c @@ -0,0 +1,222 @@ +// 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/of.h> +#include <linux/property.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 */ +#define LM70_CHIP_TMP122 4 /* TI TMP122/TMP124 */ +#define LM70_CHIP_TMP125 5 /* TI TMP125 */ + +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. + * + * TMP125: + * MSB/D15 is a leading zero. D14 is the sign-bit. This is + * followed by 9 temperature bits (D13..D5) in 2's complement + * data format with a resolution of 0.25 degrees celsius per unit. + * LSB 5 bits (D4..D0) share the same value as D5 and get discarded. + */ + 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; + + case LM70_CHIP_TMP125: + val = (sign_extend32(raw, 14) / 32) * 250; + 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,tmp125", + .data = (void *) LM70_CHIP_TMP125, + }, + { + .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) +{ + struct device *hwmon_dev; + struct lm70 *p_lm70; + int chip; + + if (dev_fwnode(&spi->dev)) + chip = (int)(uintptr_t)device_get_match_data(&spi->dev); + else + chip = spi_get_device_id(spi)->driver_data; + + + /* signaling is SPI_MODE_0 */ + if ((spi->mode & SPI_MODE_X_MASK) != SPI_MODE_0) + 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 }, + { "tmp125", LM70_CHIP_TMP125 }, + { "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"); |