xref: /openbmc/linux/drivers/w1/slaves/w1_ds2413.c (revision 921e0f2f)
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 
state_read(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t count)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 
output_write(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t count)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 	/*
103 	 * according to the DS2413 datasheet the most significant 6 bits
104 	 * should be set to "1"s, so do it now
105 	 */
106 	*buf = *buf | 0xFC;
107 
108 	while (retries--) {
109 		w1_buf[0] = W1_F3A_FUNC_PIO_ACCESS_WRITE;
110 		w1_buf[1] = *buf;
111 		w1_buf[2] = ~(*buf);
112 		w1_write_block(sl->master, w1_buf, 3);
113 
114 		if (w1_read_8(sl->master) == W1_F3A_SUCCESS_CONFIRM_BYTE) {
115 			bytes_written = 1;
116 			goto out;
117 		}
118 		if (w1_reset_resume_command(sl->master))
119 			goto out; /* unrecoverable error */
120 
121 		dev_warn(&sl->dev, "PIO_ACCESS_WRITE error, retries left: %d\n", retries);
122 	}
123 
124 out:
125 	mutex_unlock(&sl->master->bus_mutex);
126 	dev_dbg(&sl->dev, "%s, mutex unlocked, retries: %d\n",
127 		(bytes_written > 0) ? "succeeded" : "error", retries);
128 	return bytes_written;
129 }
130 
131 static BIN_ATTR(output, 0664, NULL, output_write, 1);
132 
133 static struct bin_attribute *w1_f3a_bin_attrs[] = {
134 	&bin_attr_state,
135 	&bin_attr_output,
136 	NULL,
137 };
138 
139 static const struct attribute_group w1_f3a_group = {
140 	.bin_attrs = w1_f3a_bin_attrs,
141 };
142 
143 static const struct attribute_group *w1_f3a_groups[] = {
144 	&w1_f3a_group,
145 	NULL,
146 };
147 
148 static const struct w1_family_ops w1_f3a_fops = {
149 	.groups		= w1_f3a_groups,
150 };
151 
152 static struct w1_family w1_family_3a = {
153 	.fid = W1_FAMILY_DS2413,
154 	.fops = &w1_f3a_fops,
155 };
156 module_w1_family(w1_family_3a);
157 
158 MODULE_AUTHOR("Mariusz Bialonczyk <manio@skyboo.net>");
159 MODULE_DESCRIPTION("w1 family 3a driver for DS2413 2 Pin IO");
160 MODULE_LICENSE("GPL");
161 MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS2413));
162