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 #include <linux/init.h> 28 #include <linux/module.h> 29 #include <linux/kernel.h> 30 #include <linux/device.h> 31 #include <linux/err.h> 32 #include <linux/sysfs.h> 33 #include <linux/hwmon.h> 34 #include <linux/mutex.h> 35 #include <linux/spi/spi.h> 36 37 38 #define DRVNAME "lm70" 39 40 #define LM70_CHIP_LM70 0 /* original NS LM70 */ 41 #define LM70_CHIP_TMP121 1 /* TI TMP121/TMP123 */ 42 43 struct lm70 { 44 struct device *hwmon_dev; 45 struct mutex lock; 46 unsigned int chip; 47 }; 48 49 /* sysfs hook function */ 50 static ssize_t lm70_sense_temp(struct device *dev, 51 struct device_attribute *attr, char *buf) 52 { 53 struct spi_device *spi = to_spi_device(dev); 54 int status, val = 0; 55 u8 rxbuf[2]; 56 s16 raw=0; 57 struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev); 58 59 if (mutex_lock_interruptible(&p_lm70->lock)) 60 return -ERESTARTSYS; 61 62 /* 63 * spi_read() requires a DMA-safe buffer; so we use 64 * spi_write_then_read(), transmitting 0 bytes. 65 */ 66 status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2); 67 if (status < 0) { 68 printk(KERN_WARNING 69 "spi_write_then_read failed with status %d\n", status); 70 goto out; 71 } 72 raw = (rxbuf[0] << 8) + rxbuf[1]; 73 dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n", 74 rxbuf[0], rxbuf[1], raw); 75 76 /* 77 * LM70: 78 * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's 79 * complement value. Only the MSB 11 bits (1 sign + 10 temperature 80 * bits) are meaningful; the LSB 5 bits are to be discarded. 81 * See the datasheet. 82 * 83 * Further, each bit represents 0.25 degrees Celsius; so, multiply 84 * by 0.25. Also multiply by 1000 to represent in millidegrees 85 * Celsius. 86 * So it's equivalent to multiplying by 0.25 * 1000 = 250. 87 * 88 * TMP121/TMP123: 89 * 13 bits of 2's complement data, discard LSB 3 bits, 90 * resolution 0.0625 degrees celsius. 91 */ 92 switch (p_lm70->chip) { 93 case LM70_CHIP_LM70: 94 val = ((int)raw / 32) * 250; 95 break; 96 97 case LM70_CHIP_TMP121: 98 val = ((int)raw / 8) * 625 / 10; 99 break; 100 } 101 102 status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */ 103 out: 104 mutex_unlock(&p_lm70->lock); 105 return status; 106 } 107 108 static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL); 109 110 static ssize_t lm70_show_name(struct device *dev, struct device_attribute 111 *devattr, char *buf) 112 { 113 struct lm70 *p_lm70 = dev_get_drvdata(dev); 114 int ret; 115 116 switch (p_lm70->chip) { 117 case LM70_CHIP_LM70: 118 ret = sprintf(buf, "lm70\n"); 119 break; 120 case LM70_CHIP_TMP121: 121 ret = sprintf(buf, "tmp121\n"); 122 break; 123 default: 124 ret = -EINVAL; 125 } 126 return ret; 127 } 128 129 static DEVICE_ATTR(name, S_IRUGO, lm70_show_name, NULL); 130 131 /*----------------------------------------------------------------------*/ 132 133 static int __devinit common_probe(struct spi_device *spi, int chip) 134 { 135 struct lm70 *p_lm70; 136 int status; 137 138 /* NOTE: we assume 8-bit words, and convert to 16 bits manually */ 139 140 p_lm70 = kzalloc(sizeof *p_lm70, GFP_KERNEL); 141 if (!p_lm70) 142 return -ENOMEM; 143 144 mutex_init(&p_lm70->lock); 145 p_lm70->chip = chip; 146 147 /* sysfs hook */ 148 p_lm70->hwmon_dev = hwmon_device_register(&spi->dev); 149 if (IS_ERR(p_lm70->hwmon_dev)) { 150 dev_dbg(&spi->dev, "hwmon_device_register failed.\n"); 151 status = PTR_ERR(p_lm70->hwmon_dev); 152 goto out_dev_reg_failed; 153 } 154 dev_set_drvdata(&spi->dev, p_lm70); 155 156 if ((status = device_create_file(&spi->dev, &dev_attr_temp1_input)) 157 || (status = device_create_file(&spi->dev, &dev_attr_name))) { 158 dev_dbg(&spi->dev, "device_create_file failure.\n"); 159 goto out_dev_create_file_failed; 160 } 161 162 return 0; 163 164 out_dev_create_file_failed: 165 device_remove_file(&spi->dev, &dev_attr_temp1_input); 166 hwmon_device_unregister(p_lm70->hwmon_dev); 167 out_dev_reg_failed: 168 dev_set_drvdata(&spi->dev, NULL); 169 kfree(p_lm70); 170 return status; 171 } 172 173 static int __devinit lm70_probe(struct spi_device *spi) 174 { 175 /* signaling is SPI_MODE_0 on a 3-wire link (shared SI/SO) */ 176 if ((spi->mode & (SPI_CPOL | SPI_CPHA)) || !(spi->mode & SPI_3WIRE)) 177 return -EINVAL; 178 179 return common_probe(spi, LM70_CHIP_LM70); 180 } 181 182 static int __devinit tmp121_probe(struct spi_device *spi) 183 { 184 /* signaling is SPI_MODE_0 with only MISO connected */ 185 if (spi->mode & (SPI_CPOL | SPI_CPHA)) 186 return -EINVAL; 187 188 return common_probe(spi, LM70_CHIP_TMP121); 189 } 190 191 static int __devexit lm70_remove(struct spi_device *spi) 192 { 193 struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev); 194 195 device_remove_file(&spi->dev, &dev_attr_temp1_input); 196 device_remove_file(&spi->dev, &dev_attr_name); 197 hwmon_device_unregister(p_lm70->hwmon_dev); 198 dev_set_drvdata(&spi->dev, NULL); 199 kfree(p_lm70); 200 201 return 0; 202 } 203 204 static struct spi_driver tmp121_driver = { 205 .driver = { 206 .name = "tmp121", 207 .owner = THIS_MODULE, 208 }, 209 .probe = tmp121_probe, 210 .remove = __devexit_p(lm70_remove), 211 }; 212 213 static struct spi_driver lm70_driver = { 214 .driver = { 215 .name = "lm70", 216 .owner = THIS_MODULE, 217 }, 218 .probe = lm70_probe, 219 .remove = __devexit_p(lm70_remove), 220 }; 221 222 static int __init init_lm70(void) 223 { 224 int ret = spi_register_driver(&lm70_driver); 225 if (ret) 226 return ret; 227 228 ret = spi_register_driver(&tmp121_driver); 229 if (ret) 230 spi_unregister_driver(&lm70_driver); 231 232 return ret; 233 } 234 235 static void __exit cleanup_lm70(void) 236 { 237 spi_unregister_driver(&lm70_driver); 238 spi_unregister_driver(&tmp121_driver); 239 } 240 241 module_init(init_lm70); 242 module_exit(cleanup_lm70); 243 244 MODULE_AUTHOR("Kaiwan N Billimoria"); 245 MODULE_DESCRIPTION("NS LM70 / TI TMP121/TMP123 Linux driver"); 246 MODULE_LICENSE("GPL"); 247