root/drivers/w1/slaves/w1_ds2413.c

DEFINITIONS

1. state_read
2. output_write

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * w1_ds2413.c - w1 family 3a (DS2413) driver
   4  * based on w1_ds2408.c by Jean-Francois Dagenais <dagenaisj@sonatest.com>
   5  *
   6  * Copyright (c) 2013 Mariusz Bialonczyk <manio@skyboo.net>
   7  */
   8 
   9 #include <linux/kernel.h>
  10 #include <linux/module.h>
  11 #include <linux/moduleparam.h>
  12 #include <linux/device.h>
  13 #include <linux/types.h>
  14 #include <linux/delay.h>
  15 #include <linux/slab.h>
  16 
  17 #include <linux/w1.h>
  18 
  19 #define W1_FAMILY_DS2413        0x3A
  20 
  21 #define W1_F3A_RETRIES                     3
  22 #define W1_F3A_FUNC_PIO_ACCESS_READ        0xF5
  23 #define W1_F3A_FUNC_PIO_ACCESS_WRITE       0x5A
  24 #define W1_F3A_SUCCESS_CONFIRM_BYTE        0xAA
  25 #define W1_F3A_INVALID_PIO_STATE           0xFF
  26 
  27 static ssize_t state_read(struct file *filp, struct kobject *kobj,
  28                           struct bin_attribute *bin_attr, char *buf, loff_t off,
  29                           size_t count)
  30 {
  31         struct w1_slave *sl = kobj_to_w1_slave(kobj);
  32         unsigned int retries = W1_F3A_RETRIES;
  33         ssize_t bytes_read = -EIO;
  34         u8 state;
  35 
  36         dev_dbg(&sl->dev,
  37                 "Reading %s kobj: %p, off: %0#10x, count: %zu, buff addr: %p",
  38                 bin_attr->attr.name, kobj, (unsigned int)off, count, buf);
  39 
  40         if (off != 0)
  41                 return 0;
  42         if (!buf)
  43                 return -EINVAL;
  44 
  45         mutex_lock(&sl->master->bus_mutex);
  46         dev_dbg(&sl->dev, "mutex locked");
  47 
  48 next:
  49         if (w1_reset_select_slave(sl))
  50                 goto out;
  51 
  52         while (retries--) {
  53                 w1_write_8(sl->master, W1_F3A_FUNC_PIO_ACCESS_READ);
  54 
  55                 state = w1_read_8(sl->master);
  56                 if ((state & 0x0F) == ((~state >> 4) & 0x0F)) {
  57                         /* complement is correct */
  58                         *buf = state;
  59                         bytes_read = 1;
  60                         goto out;
  61                 } else if (state == W1_F3A_INVALID_PIO_STATE) {
  62                         /* slave didn't respond, try to select it again */
  63                         dev_warn(&sl->dev, "slave device did not respond to PIO_ACCESS_READ, " \
  64                                             "reselecting, retries left: %d\n", retries);
  65                         goto next;
  66                 }
  67 
  68                 if (w1_reset_resume_command(sl->master))
  69                         goto out; /* unrecoverable error */
  70 
  71                 dev_warn(&sl->dev, "PIO_ACCESS_READ error, retries left: %d\n", retries);
  72         }
  73 
  74 out:
  75         mutex_unlock(&sl->master->bus_mutex);
  76         dev_dbg(&sl->dev, "%s, mutex unlocked, retries: %d\n",
  77                 (bytes_read > 0) ? "succeeded" : "error", retries);
  78         return bytes_read;
  79 }
  80 
  81 static BIN_ATTR_RO(state, 1);
  82 
  83 static ssize_t output_write(struct file *filp, struct kobject *kobj,
  84                             struct bin_attribute *bin_attr, char *buf,
  85                             loff_t off, size_t count)
  86 {
  87         struct w1_slave *sl = kobj_to_w1_slave(kobj);
  88         u8 w1_buf[3];
  89         unsigned int retries = W1_F3A_RETRIES;
  90         ssize_t bytes_written = -EIO;
  91 
  92         if (count != 1 || off != 0)
  93                 return -EFAULT;
  94 
  95         dev_dbg(&sl->dev, "locking mutex for write_output");
  96         mutex_lock(&sl->master->bus_mutex);
  97         dev_dbg(&sl->dev, "mutex locked");
  98 
  99         if (w1_reset_select_slave(sl))
 100                 goto out;
 101 
 102         /* according to the DS2413 datasheet the most significant 6 bits
 103            should be set to "1"s, so do it now */
 104         *buf = *buf | 0xFC;
 105 
 106         while (retries--) {
 107                 w1_buf[0] = W1_F3A_FUNC_PIO_ACCESS_WRITE;
 108                 w1_buf[1] = *buf;
 109                 w1_buf[2] = ~(*buf);
 110                 w1_write_block(sl->master, w1_buf, 3);
 111 
 112                 if (w1_read_8(sl->master) == W1_F3A_SUCCESS_CONFIRM_BYTE) {
 113                         bytes_written = 1;
 114                         goto out;
 115                 }
 116                 if (w1_reset_resume_command(sl->master))
 117                         goto out; /* unrecoverable error */
 118 
 119                 dev_warn(&sl->dev, "PIO_ACCESS_WRITE error, retries left: %d\n", retries);
 120         }
 121 
 122 out:
 123         mutex_unlock(&sl->master->bus_mutex);
 124         dev_dbg(&sl->dev, "%s, mutex unlocked, retries: %d\n",
 125                 (bytes_written > 0) ? "succeeded" : "error", retries);
 126         return bytes_written;
 127 }
 128 
 129 static BIN_ATTR(output, S_IRUGO | S_IWUSR | S_IWGRP, NULL, output_write, 1);
 130 
 131 static struct bin_attribute *w1_f3a_bin_attrs[] = {
 132         &bin_attr_state,
 133         &bin_attr_output,
 134         NULL,
 135 };
 136 
 137 static const struct attribute_group w1_f3a_group = {
 138         .bin_attrs = w1_f3a_bin_attrs,
 139 };
 140 
 141 static const struct attribute_group *w1_f3a_groups[] = {
 142         &w1_f3a_group,
 143         NULL,
 144 };
 145 
 146 static struct w1_family_ops w1_f3a_fops = {
 147         .groups         = w1_f3a_groups,
 148 };
 149 
 150 static struct w1_family w1_family_3a = {
 151         .fid = W1_FAMILY_DS2413,
 152         .fops = &w1_f3a_fops,
 153 };
 154 module_w1_family(w1_family_3a);
 155 
 156 MODULE_AUTHOR("Mariusz Bialonczyk <manio@skyboo.net>");
 157 MODULE_DESCRIPTION("w1 family 3a driver for DS2413 2 Pin IO");
 158 MODULE_LICENSE("GPL");
 159 MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS2413));