1 /* 2 * lm70.c 3 * 4 * The LM70 is a temperature sensor chip from National Semiconductor (NS). 5 * Copyright (C) 2006 Kaiwan N Billimoria <kaiwan@designergraphix.com> 6 * 7 * The LM70 communicates with a host processor via an SPI/Microwire Bus 8 * interface. The complete datasheet is available at National's website 9 * here: 10 * http://www.national.com/pf/LM/LM70.html 11 * 12 * This program is free software; you can redistribute it and/or modify 13 * it under the terms of the GNU General Public License as published by 14 * the Free Software Foundation; either version 2 of the License, or 15 * (at your option) any later version. 16 * 17 * This program is distributed in the hope that it will be useful, 18 * but WITHOUT ANY WARRANTY; without even the implied warranty of 19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 20 * GNU General Public License for more details. 21 * 22 * You should have received a copy of the GNU General Public License 23 * along with this program; if not, write to the Free Software 24 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 25 */ 26 27 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 28 29 #include <linux/init.h> 30 #include <linux/module.h> 31 #include <linux/kernel.h> 32 #include <linux/device.h> 33 #include <linux/err.h> 34 #include <linux/sysfs.h> 35 #include <linux/hwmon.h> 36 #include <linux/mutex.h> 37 #include <linux/mod_devicetable.h> 38 #include <linux/spi/spi.h> 39 #include <linux/slab.h> 40 41 42 #define DRVNAME "lm70" 43 44 #define LM70_CHIP_LM70 0 /* original NS LM70 */ 45 #define LM70_CHIP_TMP121 1 /* TI TMP121/TMP123 */ 46 47 struct lm70 { 48 struct device *hwmon_dev; 49 struct mutex lock; 50 unsigned int chip; 51 }; 52 53 /* sysfs hook function */ 54 static ssize_t lm70_sense_temp(struct device *dev, 55 struct device_attribute *attr, char *buf) 56 { 57 struct spi_device *spi = to_spi_device(dev); 58 int status, val = 0; 59 u8 rxbuf[2]; 60 s16 raw = 0; 61 struct lm70 *p_lm70 = spi_get_drvdata(spi); 62 63 if (mutex_lock_interruptible(&p_lm70->lock)) 64 return -ERESTARTSYS; 65 66 /* 67 * spi_read() requires a DMA-safe buffer; so we use 68 * spi_write_then_read(), transmitting 0 bytes. 69 */ 70 status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2); 71 if (status < 0) { 72 pr_warn("spi_write_then_read failed with status %d\n", status); 73 goto out; 74 } 75 raw = (rxbuf[0] << 8) + rxbuf[1]; 76 dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n", 77 rxbuf[0], rxbuf[1], raw); 78 79 /* 80 * LM70: 81 * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's 82 * complement value. Only the MSB 11 bits (1 sign + 10 temperature 83 * bits) are meaningful; the LSB 5 bits are to be discarded. 84 * See the datasheet. 85 * 86 * Further, each bit represents 0.25 degrees Celsius; so, multiply 87 * by 0.25. Also multiply by 1000 to represent in millidegrees 88 * Celsius. 89 * So it's equivalent to multiplying by 0.25 * 1000 = 250. 90 * 91 * TMP121/TMP123: 92 * 13 bits of 2's complement data, discard LSB 3 bits, 93 * resolution 0.0625 degrees celsius. 94 */ 95 switch (p_lm70->chip) { 96 case LM70_CHIP_LM70: 97 val = ((int)raw / 32) * 250; 98 break; 99 100 case LM70_CHIP_TMP121: 101 val = ((int)raw / 8) * 625 / 10; 102 break; 103 } 104 105 status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */ 106 out: 107 mutex_unlock(&p_lm70->lock); 108 return status; 109 } 110 111 static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL); 112 113 static ssize_t lm70_show_name(struct device *dev, struct device_attribute 114 *devattr, char *buf) 115 { 116 struct lm70 *p_lm70 = dev_get_drvdata(dev); 117 int ret; 118 119 switch (p_lm70->chip) { 120 case LM70_CHIP_LM70: 121 ret = sprintf(buf, "lm70\n"); 122 break; 123 case LM70_CHIP_TMP121: 124 ret = sprintf(buf, "tmp121\n"); 125 break; 126 default: 127 ret = -EINVAL; 128 } 129 return ret; 130 } 131 132 static DEVICE_ATTR(name, S_IRUGO, lm70_show_name, NULL); 133 134 /*----------------------------------------------------------------------*/ 135 136 static int __devinit lm70_probe(struct spi_device *spi) 137 { 138 int chip = spi_get_device_id(spi)->driver_data; 139 struct lm70 *p_lm70; 140 int status; 141 142 /* signaling is SPI_MODE_0 for both LM70 and TMP121 */ 143 if (spi->mode & (SPI_CPOL | SPI_CPHA)) 144 return -EINVAL; 145 146 /* 3-wire link (shared SI/SO) for LM70 */ 147 if (chip == LM70_CHIP_LM70 && !(spi->mode & SPI_3WIRE)) 148 return -EINVAL; 149 150 /* NOTE: we assume 8-bit words, and convert to 16 bits manually */ 151 152 p_lm70 = kzalloc(sizeof *p_lm70, GFP_KERNEL); 153 if (!p_lm70) 154 return -ENOMEM; 155 156 mutex_init(&p_lm70->lock); 157 p_lm70->chip = chip; 158 159 spi_set_drvdata(spi, p_lm70); 160 161 status = device_create_file(&spi->dev, &dev_attr_temp1_input); 162 if (status) 163 goto out_dev_create_temp_file_failed; 164 status = device_create_file(&spi->dev, &dev_attr_name); 165 if (status) 166 goto out_dev_create_file_failed; 167 168 /* sysfs hook */ 169 p_lm70->hwmon_dev = hwmon_device_register(&spi->dev); 170 if (IS_ERR(p_lm70->hwmon_dev)) { 171 dev_dbg(&spi->dev, "hwmon_device_register failed.\n"); 172 status = PTR_ERR(p_lm70->hwmon_dev); 173 goto out_dev_reg_failed; 174 } 175 176 return 0; 177 178 out_dev_reg_failed: 179 device_remove_file(&spi->dev, &dev_attr_name); 180 out_dev_create_file_failed: 181 device_remove_file(&spi->dev, &dev_attr_temp1_input); 182 out_dev_create_temp_file_failed: 183 spi_set_drvdata(spi, NULL); 184 kfree(p_lm70); 185 return status; 186 } 187 188 static int __devexit lm70_remove(struct spi_device *spi) 189 { 190 struct lm70 *p_lm70 = spi_get_drvdata(spi); 191 192 hwmon_device_unregister(p_lm70->hwmon_dev); 193 device_remove_file(&spi->dev, &dev_attr_temp1_input); 194 device_remove_file(&spi->dev, &dev_attr_name); 195 spi_set_drvdata(spi, NULL); 196 kfree(p_lm70); 197 198 return 0; 199 } 200 201 202 static const struct spi_device_id lm70_ids[] = { 203 { "lm70", LM70_CHIP_LM70 }, 204 { "tmp121", LM70_CHIP_TMP121 }, 205 { }, 206 }; 207 MODULE_DEVICE_TABLE(spi, lm70_ids); 208 209 static struct spi_driver lm70_driver = { 210 .driver = { 211 .name = "lm70", 212 .owner = THIS_MODULE, 213 }, 214 .id_table = lm70_ids, 215 .probe = lm70_probe, 216 .remove = __devexit_p(lm70_remove), 217 }; 218 219 module_spi_driver(lm70_driver); 220 221 MODULE_AUTHOR("Kaiwan N Billimoria"); 222 MODULE_DESCRIPTION("NS LM70 / TI TMP121/TMP123 Linux driver"); 223 MODULE_LICENSE("GPL"); 224