diff options
Diffstat (limited to 'drivers/hwmon/lm70.c')
| -rw-r--r-- | drivers/hwmon/lm70.c | 181 |
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"); |