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 <linux/w1.h>
  20
  21 #define W1_FAMILY_DS2413        0x3A
  22
  23 #define W1_F3A_RETRIES                     3
  24 #define W1_F3A_FUNC_PIO_ACCESS_READ        0xF5
  25 #define W1_F3A_FUNC_PIO_ACCESS_WRITE       0x5A
  26 #define W1_F3A_SUCCESS_CONFIRM_BYTE        0xAA
  27
  28 static ssize_t state_read(struct file *filp, struct kobject *kobj,
  29                           struct bin_attribute *bin_attr, char *buf, loff_t off,
  30                           size_t count)
  31 {
  32         struct w1_slave *sl = kobj_to_w1_slave(kobj);
  33         dev_dbg(&sl->dev,
  34                 "Reading %s kobj: %p, off: %0#10x, count: %zu, buff addr: %p",
  35                 bin_attr->attr.name, kobj, (unsigned int)off, count, buf);
  36
  37         if (off != 0)
  38                 return 0;
  39         if (!buf)
  40                 return -EINVAL;
  41
  42         mutex_lock(&sl->master->bus_mutex);
  43         dev_dbg(&sl->dev, "mutex locked");
  44
  45         if (w1_reset_select_slave(sl)) {
  46                 mutex_unlock(&sl->master->bus_mutex);
  47                 return -EIO;
  48         }
  49
  50         w1_write_8(sl->master, W1_F3A_FUNC_PIO_ACCESS_READ);
  51         *buf = w1_read_8(sl->master);
  52
  53         mutex_unlock(&sl->master->bus_mutex);
  54         dev_dbg(&sl->dev, "mutex unlocked");
  55
  56         /* check for correct complement */
  57         if ((*buf & 0x0F) != ((~*buf >> 4) & 0x0F))
  58                 return -EIO;
  59         else
  60                 return 1;
  61 }
  62
  63 static BIN_ATTR_RO(state, 1);
  64
  65 static ssize_t output_write(struct file *filp, struct kobject *kobj,
  66                             struct bin_attribute *bin_attr, char *buf,
  67                             loff_t off, size_t count)
  68 {
  69         struct w1_slave *sl = kobj_to_w1_slave(kobj);
  70         u8 w1_buf[3];
  71         unsigned int retries = W1_F3A_RETRIES;
  72
  73         if (count != 1 || off != 0)
  74                 return -EFAULT;
  75
  76         dev_dbg(&sl->dev, "locking mutex for write_output");
  77         mutex_lock(&sl->master->bus_mutex);
  78         dev_dbg(&sl->dev, "mutex locked");
  79
  80         if (w1_reset_select_slave(sl))
  81                 goto error;
  82
  83         /* according to the DS2413 datasheet the most significant 6 bits
  84            should be set to "1"s, so do it now */
  85         *buf = *buf | 0xFC;
  86
  87         while (retries--) {
  88                 w1_buf[0] = W1_F3A_FUNC_PIO_ACCESS_WRITE;
  89                 w1_buf[1] = *buf;
  90                 w1_buf[2] = ~(*buf);
  91                 w1_write_block(sl->master, w1_buf, 3);
  92
  93                 if (w1_read_8(sl->master) == W1_F3A_SUCCESS_CONFIRM_BYTE) {
  94                         mutex_unlock(&sl->master->bus_mutex);
  95                         dev_dbg(&sl->dev, "mutex unlocked, retries:%d", retries);
  96                         return 1;
  97                 }
  98                 if (w1_reset_resume_command(sl->master))
  99                         goto error;
 100         }
 101
 102 error:
 103         mutex_unlock(&sl->master->bus_mutex);
 104         dev_dbg(&sl->dev, "mutex unlocked in error, retries:%d", retries);
 105         return -EIO;
 106 }
 107
 108 static BIN_ATTR(output, S_IRUGO | S_IWUSR | S_IWGRP, NULL, output_write, 1);
 109
 110 static struct bin_attribute *w1_f3a_bin_attrs[] = {
 111         &bin_attr_state,
 112         &bin_attr_output,
 113         NULL,
 114 };
 115
 116 static const struct attribute_group w1_f3a_group = {
 117         .bin_attrs = w1_f3a_bin_attrs,
 118 };
 119
 120 static const struct attribute_group *w1_f3a_groups[] = {
 121         &w1_f3a_group,
 122         NULL,
 123 };
 124
 125 static struct w1_family_ops w1_f3a_fops = {
 126         .groups         = w1_f3a_groups,
 127 };
 128
 129 static struct w1_family w1_family_3a = {
 130         .fid = W1_FAMILY_DS2413,
 131         .fops = &w1_f3a_fops,
 132 };
 133 module_w1_family(w1_family_3a);
 134
 135 MODULE_AUTHOR("Mariusz Bialonczyk <manio@skyboo.net>");
 136 MODULE_DESCRIPTION("w1 family 3a driver for DS2413 2 Pin IO");
 137 MODULE_LICENSE("GPL");
 138 MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS2413));