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