drivers/w1/slaves/w1_ds2413.c

   1 /*
   2  * w1_ds2413.c - w1 family 3a (DS2413) driver
   3  * based on w1_ds2408.c by Jean-Francois Dagenais <dagenaisj@sonatest.com>
   4  *
   5  * Copyright (c) 2013 Mariusz Bialonczyk <manio@skyboo.net>
   6  *
   7  * This source code is licensed under the GNU General Public License,
   8  * Version 2. See the file COPYING for more details.
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/moduleparam.h>
  14 #include <linux/device.h>
  15 #include <linux/types.h>
  16 #include <linux/delay.h>
  17 #include <linux/slab.h>
  18
  19 #include "../w1.h"
  20 #include "../w1_int.h"
  21 #include "../w1_family.h"
  22
  23 MODULE_LICENSE("GPL");
  24 MODULE_AUTHOR("Mariusz Bialonczyk <manio@skyboo.net>");
  25 MODULE_DESCRIPTION("w1 family 3a driver for DS2413 2 Pin IO");
  26 MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS2413));
  27
  28 #define W1_F3A_RETRIES                     3
  29 #define W1_F3A_FUNC_PIO_ACCESS_READ        0xF5
  30 #define W1_F3A_FUNC_PIO_ACCESS_WRITE       0x5A
  31 #define W1_F3A_SUCCESS_CONFIRM_BYTE        0xAA
  32
  33 static ssize_t state_read(struct file *filp, struct kobject *kobj,
  34                           struct bin_attribute *bin_attr, char *buf, loff_t off,
  35                           size_t count)
  36 {
  37         struct w1_slave *sl = kobj_to_w1_slave(kobj);
  38         dev_dbg(&sl->dev,
  39                 "Reading %s kobj: %p, off: %0#10x, count: %zu, buff addr: %p",
  40                 bin_attr->attr.name, kobj, (unsigned int)off, count, buf);
  41
  42         if (off != 0)
  43                 return 0;
  44         if (!buf)
  45                 return -EINVAL;
  46
  47         mutex_lock(&sl->master->bus_mutex);
  48         dev_dbg(&sl->dev, "mutex locked");
  49
  50         if (w1_reset_select_slave(sl)) {
  51                 mutex_unlock(&sl->master->bus_mutex);
  52                 return -EIO;
  53         }
  54
  55         w1_write_8(sl->master, W1_F3A_FUNC_PIO_ACCESS_READ);
  56         *buf = w1_read_8(sl->master);
  57
  58         mutex_unlock(&sl->master->bus_mutex);
  59         dev_dbg(&sl->dev, "mutex unlocked");
  60
  61         /* check for correct complement */
  62         if ((*buf & 0x0F) != ((~*buf >> 4) & 0x0F))
  63                 return -EIO;
  64         else
  65                 return 1;
  66 }
  67
  68 static BIN_ATTR_RO(state, 1);
  69
  70 static ssize_t output_write(struct file *filp, struct kobject *kobj,
  71                             struct bin_attribute *bin_attr, char *buf,
  72                             loff_t off, size_t count)
  73 {
  74         struct w1_slave *sl = kobj_to_w1_slave(kobj);
  75         u8 w1_buf[3];
  76         unsigned int retries = W1_F3A_RETRIES;
  77
  78         if (count != 1 || off != 0)
  79                 return -EFAULT;
  80
  81         dev_dbg(&sl->dev, "locking mutex for write_output");
  82         mutex_lock(&sl->master->bus_mutex);
  83         dev_dbg(&sl->dev, "mutex locked");
  84
  85         if (w1_reset_select_slave(sl))
  86                 goto error;
  87
  88         /* according to the DS2413 datasheet the most significant 6 bits
  89            should be set to "1"s, so do it now */
  90         *buf = *buf | 0xFC;
  91
  92         while (retries--) {
  93                 w1_buf[0] = W1_F3A_FUNC_PIO_ACCESS_WRITE;
  94                 w1_buf[1] = *buf;
  95                 w1_buf[2] = ~(*buf);
  96                 w1_write_block(sl->master, w1_buf, 3);
  97
  98                 if (w1_read_8(sl->master) == W1_F3A_SUCCESS_CONFIRM_BYTE) {
  99                         mutex_unlock(&sl->master->bus_mutex);
 100                         dev_dbg(&sl->dev, "mutex unlocked, retries:%d", retries);
 101                         return 1;
 102                 }
 103                 if (w1_reset_resume_command(sl->master))
 104                         goto error;
 105         }
 106
 107 error:
 108         mutex_unlock(&sl->master->bus_mutex);
 109         dev_dbg(&sl->dev, "mutex unlocked in error, retries:%d", retries);
 110         return -EIO;
 111 }
 112
 113 static BIN_ATTR(output, S_IRUGO | S_IWUSR | S_IWGRP, NULL, output_write, 1);
 114
 115 static struct bin_attribute *w1_f3a_bin_attrs[] = {
 116         &bin_attr_state,
 117         &bin_attr_output,
 118         NULL,
 119 };
 120
 121 static const struct attribute_group w1_f3a_group = {
 122         .bin_attrs = w1_f3a_bin_attrs,
 123 };
 124
 125 static const struct attribute_group *w1_f3a_groups[] = {
 126         &w1_f3a_group,
 127         NULL,
 128 };
 129
 130 static struct w1_family_ops w1_f3a_fops = {
 131         .groups         = w1_f3a_groups,
 132 };
 133
 134 static struct w1_family w1_family_3a = {
 135         .fid = W1_FAMILY_DS2413,
 136         .fops = &w1_f3a_fops,
 137 };
 138
 139 static int __init w1_f3a_init(void)
 140 {
 141         return w1_register_family(&w1_family_3a);
 142 }
 143
 144 static void __exit w1_f3a_exit(void)
 145 {
 146         w1_unregister_family(&w1_family_3a);
 147 }
 148
 149 module_init(w1_f3a_init);
 150 module_exit(w1_f3a_exit);