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/mod_devicetable.h> 36 #include <linux/spi/spi.h> 37 #include <linux/slab.h> 38 39 40 #define DRVNAME "lm70" 41 42 #define LM70_CHIP_LM70 0 /* original NS LM70 */ 43 #define LM70_CHIP_TMP121 1 /* TI TMP121/TMP123 */ 44 45 struct lm70 { 46 struct device *hwmon_dev; 47 struct mutex lock; 48 unsigned int chip; 49 }; 50 51 /* sysfs hook function */ 52 static ssize_t lm70_sense_temp(struct device *dev, 53 struct device_attribute *attr, char *buf) 54 { 55 struct spi_device *spi = to_spi_device(dev); 56 int status, val = 0; 57 u8 rxbuf[2]; 58 s16 raw=0; 59 struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev); 60 61 if (mutex_lock_interruptible(&p_lm70->lock)) 62 return -ERESTARTSYS; 63 64 /* 65 * spi_read() requires a DMA-safe buffer; so we use 66 * spi_write_then_read(), transmitting 0 bytes. 67 */ 68 status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2); 69 if (status < 0) { 70 printk(KERN_WARNING 71 "spi_write_then_read failed with status %d\n", status); 72 goto out; 73 } 74 raw = (rxbuf[0] << 8) + rxbuf[1]; 75 dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n", 76 rxbuf[0], rxbuf[1], raw); 77 78 /* 79 * LM70: 80 * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's 81 * complement value. Only the MSB 11 bits (1 sign + 10 temperature 82 * bits) are meaningful; the LSB 5 bits are to be discarded. 83 * See the datasheet. 84 * 85 * Further, each bit represents 0.25 degrees Celsius; so, multiply 86 * by 0.25. Also multiply by 1000 to represent in millidegrees 87 * Celsius. 88 * So it's equivalent to multiplying by 0.25 * 1000 = 250. 89 * 90 * TMP121/TMP123: 91 * 13 bits of 2's complement data, discard LSB 3 bits, 92 * resolution 0.0625 degrees celsius. 93 */ 94 switch (p_lm70->chip) { 95 case LM70_CHIP_LM70: 96 val = ((int)raw / 32) * 250; 97 break; 98 99 case LM70_CHIP_TMP121: 100 val = ((int)raw / 8) * 625 / 10; 101 break; 102 } 103 104 status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */ 105 out: 106 mutex_unlock(&p_lm70->lock); 107 return status; 108 } 109 110 static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL); 111 112 static ssize_t lm70_show_name(struct device *dev, struct device_attribute 113 *devattr, char *buf) 114 { 115 struct lm70 *p_lm70 = dev_get_drvdata(dev); 116 int ret; 117 118 switch (p_lm70->chip) { 119 case LM70_CHIP_LM70: 120 ret = sprintf(buf, "lm70\n"); 121 break; 122 case LM70_CHIP_TMP121: 123 ret = sprintf(buf, "tmp121\n"); 124 break; 125 default: 126 ret = -EINVAL; 127 } 128 return ret; 129 } 130 131 static DEVICE_ATTR(name, S_IRUGO, lm70_show_name, NULL); 132 133 /*----------------------------------------------------------------------*/ 134 135 static int __devinit lm70_probe(struct spi_device *spi) 136 { 137 int chip = spi_get_device_id(spi)->driver_data; 138 struct lm70 *p_lm70; 139 int status; 140 141 /* signaling is SPI_MODE_0 for both LM70 and TMP121 */ 142 if (spi->mode & (SPI_CPOL | SPI_CPHA)) 143 return -EINVAL; 144 145 /* 3-wire link (shared SI/SO) for LM70 */ 146 if (chip == LM70_CHIP_LM70 && !(spi->mode & SPI_3WIRE)) 147 return -EINVAL; 148 149 /* NOTE: we assume 8-bit words, and convert to 16 bits manually */ 150 151 p_lm70 = kzalloc(sizeof *p_lm70, GFP_KERNEL); 152 if (!p_lm70) 153 return -ENOMEM; 154 155 mutex_init(&p_lm70->lock); 156 p_lm70->chip = chip; 157 158 /* sysfs hook */ 159 p_lm70->hwmon_dev = hwmon_device_register(&spi->dev); 160 if (IS_ERR(p_lm70->hwmon_dev)) { 161 dev_dbg(&spi->dev, "hwmon_device_register failed.\n"); 162 status = PTR_ERR(p_lm70->hwmon_dev); 163 goto out_dev_reg_failed; 164 } 165 dev_set_drvdata(&spi->dev, p_lm70); 166 167 if ((status = device_create_file(&spi->dev, &dev_attr_temp1_input)) 168 || (status = device_create_file(&spi->dev, &dev_attr_name))) { 169 dev_dbg(&spi->dev, "device_create_file failure.\n"); 170 goto out_dev_create_file_failed; 171 } 172 173 return 0; 174 175 out_dev_create_file_failed: 176 device_remove_file(&spi->dev, &dev_attr_temp1_input); 177 hwmon_device_unregister(p_lm70->hwmon_dev); 178 out_dev_reg_failed: 179 dev_set_drvdata(&spi->dev, NULL); 180 kfree(p_lm70); 181 return status; 182 } 183 184 static int __devexit lm70_remove(struct spi_device *spi) 185 { 186 struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev); 187 188 device_remove_file(&spi->dev, &dev_attr_temp1_input); 189 device_remove_file(&spi->dev, &dev_attr_name); 190 hwmon_device_unregister(p_lm70->hwmon_dev); 191 dev_set_drvdata(&spi->dev, NULL); 192 kfree(p_lm70); 193 194 return 0; 195 } 196 197 198 static const struct spi_device_id lm70_ids[] = { 199 { "lm70", LM70_CHIP_LM70 }, 200 { "tmp121", LM70_CHIP_TMP121 }, 201 { }, 202 }; 203 MODULE_DEVICE_TABLE(spi, lm70_ids); 204 205 static struct spi_driver lm70_driver = { 206 .driver = { 207 .name = "lm70", 208 .owner = THIS_MODULE, 209 }, 210 .id_table = lm70_ids, 211 .probe = lm70_probe, 212 .remove = __devexit_p(lm70_remove), 213 }; 214 215 static int __init init_lm70(void) 216 { 217 return spi_register_driver(&lm70_driver); 218 } 219 220 static void __exit cleanup_lm70(void) 221 { 222 spi_unregister_driver(&lm70_driver); 223 } 224 225 module_init(init_lm70); 226 module_exit(cleanup_lm70); 227 228 MODULE_AUTHOR("Kaiwan N Billimoria"); 229 MODULE_DESCRIPTION("NS LM70 / TI TMP121/TMP123 Linux driver"); 230 MODULE_LICENSE("GPL"); 231