Kaiwan N Billimoria | e1a8e91 | 2006-06-12 22:00:05 +0200 | [diff] [blame] | 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/spi/spi.h> |
| 35 | #include <asm/semaphore.h> |
| 36 | |
| 37 | #define DRVNAME "lm70" |
| 38 | |
| 39 | struct lm70 { |
| 40 | struct class_device *cdev; |
| 41 | struct semaphore sem; |
| 42 | }; |
| 43 | |
| 44 | /* sysfs hook function */ |
| 45 | static ssize_t lm70_sense_temp(struct device *dev, |
| 46 | struct device_attribute *attr, char *buf) |
| 47 | { |
| 48 | struct spi_device *spi = to_spi_device(dev); |
| 49 | int status, val; |
| 50 | u8 rxbuf[2]; |
| 51 | s16 raw=0; |
| 52 | struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev); |
| 53 | |
| 54 | if (down_interruptible(&p_lm70->sem)) |
| 55 | return -ERESTARTSYS; |
| 56 | |
| 57 | /* |
| 58 | * spi_read() requires a DMA-safe buffer; so we use |
| 59 | * spi_write_then_read(), transmitting 0 bytes. |
| 60 | */ |
| 61 | status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2); |
| 62 | if (status < 0) { |
| 63 | printk(KERN_WARNING |
| 64 | "spi_write_then_read failed with status %d\n", status); |
| 65 | goto out; |
| 66 | } |
| 67 | dev_dbg(dev, "rxbuf[1] : 0x%x rxbuf[0] : 0x%x\n", rxbuf[1], rxbuf[0]); |
| 68 | |
| 69 | raw = (rxbuf[1] << 8) + rxbuf[0]; |
| 70 | dev_dbg(dev, "raw=0x%x\n", raw); |
| 71 | |
| 72 | /* |
| 73 | * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's |
| 74 | * complement value. Only the MSB 11 bits (1 sign + 10 temperature |
| 75 | * bits) are meaningful; the LSB 5 bits are to be discarded. |
| 76 | * See the datasheet. |
| 77 | * |
| 78 | * Further, each bit represents 0.25 degrees Celsius; so, multiply |
| 79 | * by 0.25. Also multiply by 1000 to represent in millidegrees |
| 80 | * Celsius. |
| 81 | * So it's equivalent to multiplying by 0.25 * 1000 = 250. |
| 82 | */ |
| 83 | val = ((int)raw/32) * 250; |
Jean Delvare | 67f921d | 2007-08-17 17:31:35 +0200 | [diff] [blame^] | 84 | status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */ |
Kaiwan N Billimoria | e1a8e91 | 2006-06-12 22:00:05 +0200 | [diff] [blame] | 85 | out: |
| 86 | up(&p_lm70->sem); |
| 87 | return status; |
| 88 | } |
| 89 | |
| 90 | static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL); |
| 91 | |
Jean Delvare | 67f921d | 2007-08-17 17:31:35 +0200 | [diff] [blame^] | 92 | static ssize_t lm70_show_name(struct device *dev, struct device_attribute |
| 93 | *devattr, char *buf) |
| 94 | { |
| 95 | return sprintf(buf, "lm70\n"); |
| 96 | } |
| 97 | |
| 98 | static DEVICE_ATTR(name, S_IRUGO, lm70_show_name, NULL); |
| 99 | |
Kaiwan N Billimoria | e1a8e91 | 2006-06-12 22:00:05 +0200 | [diff] [blame] | 100 | /*----------------------------------------------------------------------*/ |
| 101 | |
| 102 | static int __devinit lm70_probe(struct spi_device *spi) |
| 103 | { |
| 104 | struct lm70 *p_lm70; |
| 105 | int status; |
| 106 | |
David Brownell | c06e677 | 2007-07-17 04:04:03 -0700 | [diff] [blame] | 107 | /* signaling is SPI_MODE_0 on a 3-wire link (shared SI/SO) */ |
| 108 | if ((spi->mode & (SPI_CPOL|SPI_CPHA)) || !(spi->mode & SPI_3WIRE)) |
| 109 | return -EINVAL; |
| 110 | |
Kaiwan N Billimoria | e1a8e91 | 2006-06-12 22:00:05 +0200 | [diff] [blame] | 111 | p_lm70 = kzalloc(sizeof *p_lm70, GFP_KERNEL); |
| 112 | if (!p_lm70) |
| 113 | return -ENOMEM; |
| 114 | |
| 115 | init_MUTEX(&p_lm70->sem); |
| 116 | |
| 117 | /* sysfs hook */ |
| 118 | p_lm70->cdev = hwmon_device_register(&spi->dev); |
| 119 | if (IS_ERR(p_lm70->cdev)) { |
| 120 | dev_dbg(&spi->dev, "hwmon_device_register failed.\n"); |
| 121 | status = PTR_ERR(p_lm70->cdev); |
| 122 | goto out_dev_reg_failed; |
| 123 | } |
| 124 | dev_set_drvdata(&spi->dev, p_lm70); |
| 125 | |
Jean Delvare | 67f921d | 2007-08-17 17:31:35 +0200 | [diff] [blame^] | 126 | if ((status = device_create_file(&spi->dev, &dev_attr_temp1_input)) |
| 127 | || (status = device_create_file(&spi->dev, &dev_attr_name))) { |
Kaiwan N Billimoria | e1a8e91 | 2006-06-12 22:00:05 +0200 | [diff] [blame] | 128 | dev_dbg(&spi->dev, "device_create_file failure.\n"); |
| 129 | goto out_dev_create_file_failed; |
| 130 | } |
| 131 | |
| 132 | return 0; |
| 133 | |
| 134 | out_dev_create_file_failed: |
Jean Delvare | 67f921d | 2007-08-17 17:31:35 +0200 | [diff] [blame^] | 135 | device_remove_file(&spi->dev, &dev_attr_temp1_input); |
Kaiwan N Billimoria | e1a8e91 | 2006-06-12 22:00:05 +0200 | [diff] [blame] | 136 | hwmon_device_unregister(p_lm70->cdev); |
| 137 | out_dev_reg_failed: |
| 138 | dev_set_drvdata(&spi->dev, NULL); |
| 139 | kfree(p_lm70); |
| 140 | return status; |
| 141 | } |
| 142 | |
Ralf Baechle | 41be722 | 2007-02-14 21:15:04 +0100 | [diff] [blame] | 143 | static int __devexit lm70_remove(struct spi_device *spi) |
Kaiwan N Billimoria | e1a8e91 | 2006-06-12 22:00:05 +0200 | [diff] [blame] | 144 | { |
| 145 | struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev); |
| 146 | |
| 147 | device_remove_file(&spi->dev, &dev_attr_temp1_input); |
Jean Delvare | 67f921d | 2007-08-17 17:31:35 +0200 | [diff] [blame^] | 148 | device_remove_file(&spi->dev, &dev_attr_name); |
Kaiwan N Billimoria | e1a8e91 | 2006-06-12 22:00:05 +0200 | [diff] [blame] | 149 | hwmon_device_unregister(p_lm70->cdev); |
| 150 | dev_set_drvdata(&spi->dev, NULL); |
| 151 | kfree(p_lm70); |
| 152 | |
| 153 | return 0; |
| 154 | } |
| 155 | |
| 156 | static struct spi_driver lm70_driver = { |
| 157 | .driver = { |
| 158 | .name = "lm70", |
| 159 | .owner = THIS_MODULE, |
| 160 | }, |
| 161 | .probe = lm70_probe, |
| 162 | .remove = __devexit_p(lm70_remove), |
| 163 | }; |
| 164 | |
| 165 | static int __init init_lm70(void) |
| 166 | { |
| 167 | return spi_register_driver(&lm70_driver); |
| 168 | } |
| 169 | |
| 170 | static void __exit cleanup_lm70(void) |
| 171 | { |
| 172 | spi_unregister_driver(&lm70_driver); |
| 173 | } |
| 174 | |
| 175 | module_init(init_lm70); |
| 176 | module_exit(cleanup_lm70); |
| 177 | |
| 178 | MODULE_AUTHOR("Kaiwan N Billimoria"); |
| 179 | MODULE_DESCRIPTION("National Semiconductor LM70 Linux driver"); |
| 180 | MODULE_LICENSE("GPL"); |