xref: /openbmc/linux/drivers/w1/slaves/w1_ds2405.c (revision 57de2dfc)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *	w1_ds2405.c
4  *
5  * Copyright (c) 2017 Maciej S. Szmigiero <mail@maciej.szmigiero.name>
6  * Based on w1_therm.c copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
7  */
8 
9 #include <linux/device.h>
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/moduleparam.h>
13 #include <linux/mutex.h>
14 #include <linux/string.h>
15 #include <linux/types.h>
16 
17 #include <linux/w1.h>
18 
19 #define W1_FAMILY_DS2405	0x05
20 
21 MODULE_LICENSE("GPL");
22 MODULE_AUTHOR("Maciej S. Szmigiero <mail@maciej.szmigiero.name>");
23 MODULE_DESCRIPTION("Driver for 1-wire Dallas DS2405 PIO.");
24 MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS2405));
25 
w1_ds2405_select(struct w1_slave * sl,bool only_active)26 static int w1_ds2405_select(struct w1_slave *sl, bool only_active)
27 {
28 	struct w1_master *dev = sl->master;
29 
30 	u64 dev_addr = le64_to_cpu(*(u64 *)&sl->reg_num);
31 	unsigned int bit_ctr;
32 
33 	if (w1_reset_bus(dev) != 0)
34 		return 0;
35 
36 	/*
37 	 * We cannot use a normal Match ROM command
38 	 * since doing so would toggle PIO state
39 	 */
40 	w1_write_8(dev, only_active ? W1_ALARM_SEARCH : W1_SEARCH);
41 
42 	for (bit_ctr = 0; bit_ctr < 64; bit_ctr++) {
43 		int bit2send = !!(dev_addr & BIT(bit_ctr));
44 		u8 ret;
45 
46 		ret = w1_triplet(dev, bit2send);
47 
48 		if ((ret & (BIT(0) | BIT(1))) ==
49 		    (BIT(0) | BIT(1))) /* no devices found */
50 			return 0;
51 
52 		if (!!(ret & BIT(2)) != bit2send)
53 			/* wrong direction taken - no such device */
54 			return 0;
55 	}
56 
57 	return 1;
58 }
59 
w1_ds2405_read_pio(struct w1_slave * sl)60 static int w1_ds2405_read_pio(struct w1_slave *sl)
61 {
62 	if (w1_ds2405_select(sl, true))
63 		return 0; /* "active" means PIO is low */
64 
65 	if (w1_ds2405_select(sl, false))
66 		return 1;
67 
68 	return -ENODEV;
69 }
70 
state_show(struct device * device,struct device_attribute * attr,char * buf)71 static ssize_t state_show(struct device *device,
72 			  struct device_attribute *attr, char *buf)
73 {
74 	struct w1_slave *sl = dev_to_w1_slave(device);
75 	struct w1_master *dev = sl->master;
76 
77 	int ret;
78 	ssize_t f_retval;
79 	u8 state;
80 
81 	ret = mutex_lock_interruptible(&dev->bus_mutex);
82 	if (ret)
83 		return ret;
84 
85 	if (!w1_ds2405_select(sl, false)) {
86 		f_retval = -ENODEV;
87 		goto out_unlock;
88 	}
89 
90 	state = w1_read_8(dev);
91 	if (state != 0 &&
92 	    state != 0xff) {
93 		dev_err(device, "non-consistent state %x\n", state);
94 		f_retval = -EIO;
95 		goto out_unlock;
96 	}
97 
98 	*buf = state ? '1' : '0';
99 	f_retval = 1;
100 
101 out_unlock:
102 	w1_reset_bus(dev);
103 	mutex_unlock(&dev->bus_mutex);
104 
105 	return f_retval;
106 }
107 
output_show(struct device * device,struct device_attribute * attr,char * buf)108 static ssize_t output_show(struct device *device,
109 			   struct device_attribute *attr, char *buf)
110 {
111 	struct w1_slave *sl = dev_to_w1_slave(device);
112 	struct w1_master *dev = sl->master;
113 
114 	int ret;
115 	ssize_t f_retval;
116 
117 	ret = mutex_lock_interruptible(&dev->bus_mutex);
118 	if (ret)
119 		return ret;
120 
121 	ret = w1_ds2405_read_pio(sl);
122 	if (ret < 0) {
123 		f_retval = ret;
124 		goto out_unlock;
125 	}
126 
127 	*buf = ret ? '1' : '0';
128 	f_retval = 1;
129 
130 out_unlock:
131 	w1_reset_bus(dev);
132 	mutex_unlock(&dev->bus_mutex);
133 
134 	return f_retval;
135 }
136 
output_store(struct device * device,struct device_attribute * attr,const char * buf,size_t count)137 static ssize_t output_store(struct device *device,
138 			    struct device_attribute *attr,
139 			    const char *buf, size_t count)
140 {
141 	struct w1_slave *sl = dev_to_w1_slave(device);
142 	struct w1_master *dev = sl->master;
143 
144 	int ret, current_pio;
145 	unsigned int val;
146 	ssize_t f_retval;
147 
148 	if (count < 1)
149 		return -EINVAL;
150 
151 	if (sscanf(buf, " %u%n", &val, &ret) < 1)
152 		return -EINVAL;
153 
154 	if (val != 0 && val != 1)
155 		return -EINVAL;
156 
157 	f_retval = ret;
158 
159 	ret = mutex_lock_interruptible(&dev->bus_mutex);
160 	if (ret)
161 		return ret;
162 
163 	current_pio = w1_ds2405_read_pio(sl);
164 	if (current_pio < 0) {
165 		f_retval = current_pio;
166 		goto out_unlock;
167 	}
168 
169 	if (current_pio == val)
170 		goto out_unlock;
171 
172 	if (w1_reset_bus(dev) != 0) {
173 		f_retval = -ENODEV;
174 		goto out_unlock;
175 	}
176 
177 	/*
178 	 * can't use w1_reset_select_slave() here since it uses Skip ROM if
179 	 * there is only one device on bus
180 	 */
181 	do {
182 		u64 dev_addr = le64_to_cpu(*(u64 *)&sl->reg_num);
183 		u8 cmd[9];
184 
185 		cmd[0] = W1_MATCH_ROM;
186 		memcpy(&cmd[1], &dev_addr, sizeof(dev_addr));
187 
188 		w1_write_block(dev, cmd, sizeof(cmd));
189 	} while (0);
190 
191 out_unlock:
192 	w1_reset_bus(dev);
193 	mutex_unlock(&dev->bus_mutex);
194 
195 	return f_retval;
196 }
197 
198 static DEVICE_ATTR_RO(state);
199 static DEVICE_ATTR_RW(output);
200 
201 static struct attribute *w1_ds2405_attrs[] = {
202 	&dev_attr_state.attr,
203 	&dev_attr_output.attr,
204 	NULL
205 };
206 
207 ATTRIBUTE_GROUPS(w1_ds2405);
208 
209 static const struct w1_family_ops w1_ds2405_fops = {
210 	.groups = w1_ds2405_groups
211 };
212 
213 static struct w1_family w1_family_ds2405 = {
214 	.fid = W1_FAMILY_DS2405,
215 	.fops = &w1_ds2405_fops
216 };
217 
218 module_w1_family(w1_family_ds2405);
219