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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 | /* * lm70.c * * The LM70 is a temperature sensor chip from National Semiconductor (NS). * Copyright (C) 2006 Kaiwan N Billimoria <kaiwan@designergraphix.com> * * The LM70 communicates with a host processor via an SPI/Microwire Bus * interface. The complete datasheet is available at National's website * here: * http://www.national.com/pf/LM/LM70.html * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #include <linux/init.h> #include <linux/module.h> #include <linux/kernel.h> #include <linux/device.h> #include <linux/err.h> #include <linux/sysfs.h> #include <linux/hwmon.h> #include <linux/spi/spi.h> #include <asm/semaphore.h> #define DRVNAME "lm70" struct lm70 { struct class_device *cdev; struct semaphore sem; }; /* sysfs hook function */ static ssize_t lm70_sense_temp(struct device *dev, struct device_attribute *attr, char *buf) { struct spi_device *spi = to_spi_device(dev); int status, val; u8 rxbuf[2]; s16 raw=0; struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev); if (down_interruptible(&p_lm70->sem)) return -ERESTARTSYS; /* * spi_read() requires a DMA-safe buffer; so we use * spi_write_then_read(), transmitting 0 bytes. */ status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2); if (status < 0) { printk(KERN_WARNING "spi_write_then_read failed with status %d\n", status); goto out; } dev_dbg(dev, "rxbuf[1] : 0x%x rxbuf[0] : 0x%x\n", rxbuf[1], rxbuf[0]); raw = (rxbuf[1] << 8) + rxbuf[0]; dev_dbg(dev, "raw=0x%x\n", raw); /* * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's * complement value. Only the MSB 11 bits (1 sign + 10 temperature * bits) are meaningful; the LSB 5 bits are to be discarded. * See the datasheet. * * Further, each bit represents 0.25 degrees Celsius; so, multiply * by 0.25. Also multiply by 1000 to represent in millidegrees * Celsius. * So it's equivalent to multiplying by 0.25 * 1000 = 250. */ val = ((int)raw/32) * 250; status = sprintf(buf, "%+d\n", val); /* millidegrees Celsius */ out: up(&p_lm70->sem); return status; } static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL); /*----------------------------------------------------------------------*/ static int __devinit lm70_probe(struct spi_device *spi) { struct lm70 *p_lm70; int status; p_lm70 = kzalloc(sizeof *p_lm70, GFP_KERNEL); if (!p_lm70) return -ENOMEM; init_MUTEX(&p_lm70->sem); /* sysfs hook */ p_lm70->cdev = hwmon_device_register(&spi->dev); if (IS_ERR(p_lm70->cdev)) { dev_dbg(&spi->dev, "hwmon_device_register failed.\n"); status = PTR_ERR(p_lm70->cdev); goto out_dev_reg_failed; } dev_set_drvdata(&spi->dev, p_lm70); if ((status = device_create_file(&spi->dev, &dev_attr_temp1_input))) { dev_dbg(&spi->dev, "device_create_file failure.\n"); goto out_dev_create_file_failed; } return 0; out_dev_create_file_failed: hwmon_device_unregister(p_lm70->cdev); out_dev_reg_failed: dev_set_drvdata(&spi->dev, NULL); kfree(p_lm70); return status; } static int __devexit lm70_remove(struct spi_device *spi) { struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev); device_remove_file(&spi->dev, &dev_attr_temp1_input); hwmon_device_unregister(p_lm70->cdev); dev_set_drvdata(&spi->dev, NULL); kfree(p_lm70); return 0; } static struct spi_driver lm70_driver = { .driver = { .name = "lm70", .owner = THIS_MODULE, }, .probe = lm70_probe, .remove = __devexit_p(lm70_remove), }; static int __init init_lm70(void) { return spi_register_driver(&lm70_driver); } static void __exit cleanup_lm70(void) { spi_unregister_driver(&lm70_driver); } module_init(init_lm70); module_exit(cleanup_lm70); MODULE_AUTHOR("Kaiwan N Billimoria"); MODULE_DESCRIPTION("National Semiconductor LM70 Linux driver"); MODULE_LICENSE("GPL"); |