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1 | /* |
2 | * Copyright 2012 Red Hat Inc. | |
3 | * | |
4 | * Permission is hereby granted, free of charge, to any person obtaining a | |
5 | * copy of this software and associated documentation files (the "Software"), | |
6 | * to deal in the Software without restriction, including without limitation | |
7 | * the rights to use, copy, modify, merge, publish, distribute, sublicense, | |
8 | * and/or sell copies of the Software, and to permit persons to whom the | |
9 | * Software is furnished to do so, subject to the following conditions: | |
10 | * | |
11 | * The above copyright notice and this permission notice shall be included in | |
12 | * all copies or substantial portions of the Software. | |
13 | * | |
14 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
15 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
16 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL | |
17 | * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR | |
18 | * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, | |
19 | * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR | |
20 | * OTHER DEALINGS IN THE SOFTWARE. | |
21 | * | |
22 | * Authors: Ben Skeggs | |
23 | */ | |
24 | ||
c26fe843 | 25 | #include "priv.h" |
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26 | |
27 | #ifdef CONFIG_NOUVEAU_I2C_INTERNAL | |
28 | #define T_TIMEOUT 2200000 | |
29 | #define T_RISEFALL 1000 | |
30 | #define T_HOLD 5000 | |
31 | ||
32 | static inline void | |
33 | i2c_drive_scl(struct nouveau_i2c_port *port, int state) | |
34 | { | |
7dcd060c | 35 | port->func->drive_scl(port, state); |
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36 | } |
37 | ||
38 | static inline void | |
39 | i2c_drive_sda(struct nouveau_i2c_port *port, int state) | |
40 | { | |
7dcd060c | 41 | port->func->drive_sda(port, state); |
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42 | } |
43 | ||
44 | static inline int | |
45 | i2c_sense_scl(struct nouveau_i2c_port *port) | |
46 | { | |
7dcd060c | 47 | return port->func->sense_scl(port); |
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48 | } |
49 | ||
50 | static inline int | |
51 | i2c_sense_sda(struct nouveau_i2c_port *port) | |
52 | { | |
7dcd060c | 53 | return port->func->sense_sda(port); |
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54 | } |
55 | ||
56 | static void | |
57 | i2c_delay(struct nouveau_i2c_port *port, u32 nsec) | |
58 | { | |
59 | udelay((nsec + 500) / 1000); | |
60 | } | |
61 | ||
62 | static bool | |
63 | i2c_raise_scl(struct nouveau_i2c_port *port) | |
64 | { | |
65 | u32 timeout = T_TIMEOUT / T_RISEFALL; | |
66 | ||
67 | i2c_drive_scl(port, 1); | |
68 | do { | |
69 | i2c_delay(port, T_RISEFALL); | |
70 | } while (!i2c_sense_scl(port) && --timeout); | |
71 | ||
72 | return timeout != 0; | |
73 | } | |
74 | ||
75 | static int | |
76 | i2c_start(struct nouveau_i2c_port *port) | |
77 | { | |
78 | int ret = 0; | |
79 | ||
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80 | if (!i2c_sense_scl(port) || |
81 | !i2c_sense_sda(port)) { | |
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82 | i2c_drive_scl(port, 0); |
83 | i2c_drive_sda(port, 1); | |
84 | if (!i2c_raise_scl(port)) | |
85 | ret = -EBUSY; | |
86 | } | |
87 | ||
88 | i2c_drive_sda(port, 0); | |
89 | i2c_delay(port, T_HOLD); | |
90 | i2c_drive_scl(port, 0); | |
91 | i2c_delay(port, T_HOLD); | |
92 | return ret; | |
93 | } | |
94 | ||
95 | static void | |
96 | i2c_stop(struct nouveau_i2c_port *port) | |
97 | { | |
98 | i2c_drive_scl(port, 0); | |
99 | i2c_drive_sda(port, 0); | |
100 | i2c_delay(port, T_RISEFALL); | |
101 | ||
102 | i2c_drive_scl(port, 1); | |
103 | i2c_delay(port, T_HOLD); | |
104 | i2c_drive_sda(port, 1); | |
105 | i2c_delay(port, T_HOLD); | |
106 | } | |
107 | ||
108 | static int | |
109 | i2c_bitw(struct nouveau_i2c_port *port, int sda) | |
110 | { | |
111 | i2c_drive_sda(port, sda); | |
112 | i2c_delay(port, T_RISEFALL); | |
113 | ||
114 | if (!i2c_raise_scl(port)) | |
115 | return -ETIMEDOUT; | |
116 | i2c_delay(port, T_HOLD); | |
117 | ||
118 | i2c_drive_scl(port, 0); | |
119 | i2c_delay(port, T_HOLD); | |
120 | return 0; | |
121 | } | |
122 | ||
123 | static int | |
124 | i2c_bitr(struct nouveau_i2c_port *port) | |
125 | { | |
126 | int sda; | |
127 | ||
128 | i2c_drive_sda(port, 1); | |
129 | i2c_delay(port, T_RISEFALL); | |
130 | ||
131 | if (!i2c_raise_scl(port)) | |
132 | return -ETIMEDOUT; | |
133 | i2c_delay(port, T_HOLD); | |
134 | ||
135 | sda = i2c_sense_sda(port); | |
136 | ||
137 | i2c_drive_scl(port, 0); | |
138 | i2c_delay(port, T_HOLD); | |
139 | return sda; | |
140 | } | |
141 | ||
142 | static int | |
143 | i2c_get_byte(struct nouveau_i2c_port *port, u8 *byte, bool last) | |
144 | { | |
145 | int i, bit; | |
146 | ||
147 | *byte = 0; | |
148 | for (i = 7; i >= 0; i--) { | |
149 | bit = i2c_bitr(port); | |
150 | if (bit < 0) | |
151 | return bit; | |
152 | *byte |= bit << i; | |
153 | } | |
154 | ||
155 | return i2c_bitw(port, last ? 1 : 0); | |
156 | } | |
157 | ||
158 | static int | |
159 | i2c_put_byte(struct nouveau_i2c_port *port, u8 byte) | |
160 | { | |
161 | int i, ret; | |
162 | for (i = 7; i >= 0; i--) { | |
163 | ret = i2c_bitw(port, !!(byte & (1 << i))); | |
164 | if (ret < 0) | |
165 | return ret; | |
166 | } | |
167 | ||
168 | ret = i2c_bitr(port); | |
169 | if (ret == 1) /* nack */ | |
170 | ret = -EIO; | |
171 | return ret; | |
172 | } | |
173 | ||
174 | static int | |
175 | i2c_addr(struct nouveau_i2c_port *port, struct i2c_msg *msg) | |
176 | { | |
177 | u32 addr = msg->addr << 1; | |
178 | if (msg->flags & I2C_M_RD) | |
179 | addr |= 1; | |
180 | return i2c_put_byte(port, addr); | |
181 | } | |
182 | ||
183 | static int | |
184 | i2c_bit_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) | |
185 | { | |
7dcd060c | 186 | struct nouveau_i2c_port *port = adap->algo_data; |
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187 | struct i2c_msg *msg = msgs; |
188 | int ret = 0, mcnt = num; | |
189 | ||
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190 | ret = nouveau_i2c(port)->acquire(port, nsecs_to_jiffies(T_TIMEOUT)); |
191 | if (ret) | |
192 | return ret; | |
7dcd060c | 193 | |
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194 | while (!ret && mcnt--) { |
195 | u8 remaining = msg->len; | |
196 | u8 *ptr = msg->buf; | |
197 | ||
198 | ret = i2c_start(port); | |
199 | if (ret == 0) | |
200 | ret = i2c_addr(port, msg); | |
201 | ||
202 | if (msg->flags & I2C_M_RD) { | |
203 | while (!ret && remaining--) | |
204 | ret = i2c_get_byte(port, ptr++, !remaining); | |
205 | } else { | |
206 | while (!ret && remaining--) | |
207 | ret = i2c_put_byte(port, *ptr++); | |
208 | } | |
209 | ||
210 | msg++; | |
211 | } | |
212 | ||
213 | i2c_stop(port); | |
d2ae2eb4 | 214 | nouveau_i2c(port)->release(port); |
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215 | return (ret < 0) ? ret : num; |
216 | } | |
217 | #else | |
218 | static int | |
219 | i2c_bit_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) | |
220 | { | |
221 | return -ENODEV; | |
222 | } | |
223 | #endif | |
224 | ||
225 | static u32 | |
226 | i2c_bit_func(struct i2c_adapter *adap) | |
227 | { | |
228 | return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; | |
229 | } | |
230 | ||
231 | const struct i2c_algorithm nouveau_i2c_bit_algo = { | |
232 | .master_xfer = i2c_bit_xfer, | |
233 | .functionality = i2c_bit_func | |
234 | }; |