1 /*
2 * Copyright (c) 2016-2020 François Tigeot <ftigeot@wolfpond.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice unmodified, this list of conditions, and the following
10 * disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27 #include <linux/i2c.h>
28 #include <linux/i2c-algo-bit.h>
29
30 #include <linux/slab.h>
31
32 static struct lock i2c_lock;
33 LOCK_SYSINIT(i2c_lock, &i2c_lock, "i2cl", LK_CANRECURSE);
34
35 static void i2c_default_lock_bus(struct i2c_adapter *, unsigned int);
36 static int i2c_default_trylock_bus(struct i2c_adapter *, unsigned int);
37 static void i2c_default_unlock_bus(struct i2c_adapter *, unsigned int);
38
39 static const struct i2c_lock_operations i2c_default_lock_ops = {
40 .lock_bus = i2c_default_lock_bus,
41 .trylock_bus = i2c_default_trylock_bus,
42 .unlock_bus = i2c_default_unlock_bus,
43 };
44
45 int
i2c_add_adapter(struct i2c_adapter * adapter)46 i2c_add_adapter(struct i2c_adapter *adapter)
47 {
48 /* Linux registers a unique bus number here */
49
50 /* Setup default locking functions */
51 if (!adapter->lock_ops)
52 adapter->lock_ops = &i2c_default_lock_ops;
53
54 return 0;
55 }
56
57 void
i2c_del_adapter(struct i2c_adapter * adapter)58 i2c_del_adapter(struct i2c_adapter *adapter)
59 {
60 /* Linux deletes a unique bus number here */
61 }
62
63 int
__i2c_transfer(struct i2c_adapter * adapter,struct i2c_msg * msgs,int num)64 __i2c_transfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
65 {
66 uint64_t start_ticks;
67 int ret, tries = 0;
68
69 start_ticks = ticks;
70 do {
71 ret = adapter->algo->master_xfer(adapter, msgs, num);
72 if (ticks > start_ticks + adapter->timeout)
73 break;
74 if (ret != -EAGAIN)
75 break;
76 tries++;
77 } while (tries < adapter->retries);
78
79 return ret;
80 }
81
82 /*
83 * i2c_transfer()
84 * The original Linux implementation does:
85 * 1. return -EOPNOTSUPP if adapter->algo->master_xfer is NULL
86 * 2. try to transfer msgs by calling adapter->algo->master_xfer()
87 * 3. if it took more ticks than adapter->timeout, fail
88 * 4. if the transfer failed, retry up to adapter->retries times
89 * 5. return the result of the last call of adapter->algo->master_xfer()
90 */
91 int
i2c_transfer(struct i2c_adapter * adapter,struct i2c_msg * msgs,int num)92 i2c_transfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
93 {
94 int ret;
95
96 if (adapter->algo->master_xfer == NULL)
97 return -EOPNOTSUPP;
98
99 adapter->lock_ops->lock_bus(adapter, I2C_LOCK_SEGMENT);
100 ret = __i2c_transfer(adapter, msgs, num);
101 adapter->lock_ops->unlock_bus(adapter, I2C_LOCK_SEGMENT);
102
103 return ret;
104 }
105
106 static int
bit_xfer(struct i2c_adapter * i2c_adap,struct i2c_msg msgs[],int num)107 bit_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg msgs[], int num)
108 {
109 /* XXX Linux really does try to transfer some data here */
110 return 0;
111 }
112
113 static uint32_t
bit_func(struct i2c_adapter * adap)114 bit_func(struct i2c_adapter *adap)
115 {
116 return (I2C_FUNC_I2C | I2C_FUNC_NOSTART | I2C_FUNC_SMBUS_EMUL |
117 I2C_FUNC_SMBUS_READ_BLOCK_DATA |
118 I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
119 I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING);
120 }
121
122 const struct i2c_algorithm i2c_bit_algo = {
123 .master_xfer = bit_xfer,
124 .functionality = bit_func,
125 };
126
127 int
i2c_bit_add_bus(struct i2c_adapter * adapter)128 i2c_bit_add_bus(struct i2c_adapter *adapter)
129 {
130 adapter->algo = &i2c_bit_algo;
131 adapter->retries = 2;
132
133 return 0;
134 }
135
136 struct i2c_client *
i2c_new_device(struct i2c_adapter * adap,struct i2c_board_info const * info)137 i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
138 {
139 struct i2c_client *client;
140
141 client = kzalloc(sizeof(*client), GFP_KERNEL);
142 if (client == NULL)
143 goto done;
144
145 client->adapter = adap;
146
147 strlcpy(client->name, info->type, sizeof(client->name));
148 client->addr = info->addr;
149
150 done:
151 return client;
152 }
153
154 /* Default locking functions */
155
156 static void
i2c_default_lock_bus(struct i2c_adapter * adapter,unsigned int flags)157 i2c_default_lock_bus(struct i2c_adapter *adapter, unsigned int flags)
158 {
159 lockmgr(&i2c_lock, LK_EXCLUSIVE);
160 }
161
162 static int
i2c_default_trylock_bus(struct i2c_adapter * adapter,unsigned int flags)163 i2c_default_trylock_bus(struct i2c_adapter *adapter, unsigned int flags)
164 {
165 return mutex_trylock(&i2c_lock);
166 }
167
168 static void
i2c_default_unlock_bus(struct i2c_adapter * adapter,unsigned int flags)169 i2c_default_unlock_bus(struct i2c_adapter *adapter, unsigned int flags)
170 {
171 lockmgr(&i2c_lock, LK_RELEASE);
172 }
173