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 #include <linux/of_device.h> 41 42 43 #define DRVNAME "lm70" 44 45 #define LM70_CHIP_LM70 0 /* original NS LM70 */ 46 #define LM70_CHIP_TMP121 1 /* TI TMP121/TMP123 */ 47 #define LM70_CHIP_LM71 2 /* NS LM71 */ 48 #define LM70_CHIP_LM74 3 /* NS LM74 */ 49 #define LM70_CHIP_TMP122 4 /* TI TMP122/TMP124 */ 50 51 struct lm70 { 52 struct spi_device *spi; 53 struct mutex lock; 54 unsigned int chip; 55 }; 56 57 /* sysfs hook function */ 58 static ssize_t temp1_input_show(struct device *dev, 59 struct device_attribute *attr, char *buf) 60 { 61 struct lm70 *p_lm70 = dev_get_drvdata(dev); 62 struct spi_device *spi = p_lm70->spi; 63 int status, val = 0; 64 u8 rxbuf[2]; 65 s16 raw = 0; 66 67 if (mutex_lock_interruptible(&p_lm70->lock)) 68 return -ERESTARTSYS; 69 70 /* 71 * spi_read() requires a DMA-safe buffer; so we use 72 * spi_write_then_read(), transmitting 0 bytes. 73 */ 74 status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2); 75 if (status < 0) { 76 dev_warn(dev, "spi_write_then_read failed with status %d\n", 77 status); 78 goto out; 79 } 80 raw = (rxbuf[0] << 8) + rxbuf[1]; 81 dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n", 82 rxbuf[0], rxbuf[1], raw); 83 84 /* 85 * LM70: 86 * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's 87 * complement value. Only the MSB 11 bits (1 sign + 10 temperature 88 * bits) are meaningful; the LSB 5 bits are to be discarded. 89 * See the datasheet. 90 * 91 * Further, each bit represents 0.25 degrees Celsius; so, multiply 92 * by 0.25. Also multiply by 1000 to represent in millidegrees 93 * Celsius. 94 * So it's equivalent to multiplying by 0.25 * 1000 = 250. 95 * 96 * LM74 and TMP121/TMP122/TMP123/TMP124: 97 * 13 bits of 2's complement data, discard LSB 3 bits, 98 * resolution 0.0625 degrees celsius. 99 * 100 * LM71: 101 * 14 bits of 2's complement data, discard LSB 2 bits, 102 * resolution 0.0312 degrees celsius. 103 */ 104 switch (p_lm70->chip) { 105 case LM70_CHIP_LM70: 106 val = ((int)raw / 32) * 250; 107 break; 108 109 case LM70_CHIP_TMP121: 110 case LM70_CHIP_TMP122: 111 case LM70_CHIP_LM74: 112 val = ((int)raw / 8) * 625 / 10; 113 break; 114 115 case LM70_CHIP_LM71: 116 val = ((int)raw / 4) * 3125 / 100; 117 break; 118 } 119 120 status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */ 121 out: 122 mutex_unlock(&p_lm70->lock); 123 return status; 124 } 125 126 static DEVICE_ATTR_RO(temp1_input); 127 128 static struct attribute *lm70_attrs[] = { 129 &dev_attr_temp1_input.attr, 130 NULL 131 }; 132 133 ATTRIBUTE_GROUPS(lm70); 134 135 /*----------------------------------------------------------------------*/ 136 137 #ifdef CONFIG_OF 138 static const struct of_device_id lm70_of_ids[] = { 139 { 140 .compatible = "ti,lm70", 141 .data = (void *) LM70_CHIP_LM70, 142 }, 143 { 144 .compatible = "ti,tmp121", 145 .data = (void *) LM70_CHIP_TMP121, 146 }, 147 { 148 .compatible = "ti,tmp122", 149 .data = (void *) LM70_CHIP_TMP122, 150 }, 151 { 152 .compatible = "ti,lm71", 153 .data = (void *) LM70_CHIP_LM71, 154 }, 155 { 156 .compatible = "ti,lm74", 157 .data = (void *) LM70_CHIP_LM74, 158 }, 159 {}, 160 }; 161 MODULE_DEVICE_TABLE(of, lm70_of_ids); 162 #endif 163 164 static int lm70_probe(struct spi_device *spi) 165 { 166 const struct of_device_id *match; 167 struct device *hwmon_dev; 168 struct lm70 *p_lm70; 169 int chip; 170 171 match = of_match_device(lm70_of_ids, &spi->dev); 172 if (match) 173 chip = (int)(uintptr_t)match->data; 174 else 175 chip = spi_get_device_id(spi)->driver_data; 176 177 /* signaling is SPI_MODE_0 */ 178 if (spi->mode & (SPI_CPOL | SPI_CPHA)) 179 return -EINVAL; 180 181 /* NOTE: we assume 8-bit words, and convert to 16 bits manually */ 182 183 p_lm70 = devm_kzalloc(&spi->dev, sizeof(*p_lm70), GFP_KERNEL); 184 if (!p_lm70) 185 return -ENOMEM; 186 187 mutex_init(&p_lm70->lock); 188 p_lm70->chip = chip; 189 p_lm70->spi = spi; 190 191 hwmon_dev = devm_hwmon_device_register_with_groups(&spi->dev, 192 spi->modalias, 193 p_lm70, lm70_groups); 194 return PTR_ERR_OR_ZERO(hwmon_dev); 195 } 196 197 static const struct spi_device_id lm70_ids[] = { 198 { "lm70", LM70_CHIP_LM70 }, 199 { "tmp121", LM70_CHIP_TMP121 }, 200 { "tmp122", LM70_CHIP_TMP122 }, 201 { "lm71", LM70_CHIP_LM71 }, 202 { "lm74", LM70_CHIP_LM74 }, 203 { }, 204 }; 205 MODULE_DEVICE_TABLE(spi, lm70_ids); 206 207 static struct spi_driver lm70_driver = { 208 .driver = { 209 .name = "lm70", 210 .of_match_table = of_match_ptr(lm70_of_ids), 211 }, 212 .id_table = lm70_ids, 213 .probe = lm70_probe, 214 }; 215 216 module_spi_driver(lm70_driver); 217 218 MODULE_AUTHOR("Kaiwan N Billimoria"); 219 MODULE_DESCRIPTION("NS LM70 and compatibles Linux driver"); 220 MODULE_LICENSE("GPL"); 221