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1125 | serge | 1 | /* i2c-core.c - a device driver for the iic-bus interface */ |
2 | /* ------------------------------------------------------------------------- */ |
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3 | /* Copyright (C) 1995-99 Simon G. Vogl |
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4 | |||
5 | This program is free software; you can redistribute it and/or modify |
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6 | it under the terms of the GNU General Public License as published by |
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7 | the Free Software Foundation; either version 2 of the License, or |
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8 | (at your option) any later version. |
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9 | |||
10 | This program is distributed in the hope that it will be useful, |
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11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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13 | GNU General Public License for more details. |
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14 | |||
15 | You should have received a copy of the GNU General Public License |
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16 | along with this program; if not, write to the Free Software |
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3031 | serge | 17 | Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, |
18 | MA 02110-1301 USA. */ |
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1125 | serge | 19 | /* ------------------------------------------------------------------------- */ |
20 | |||
21 | /* With some changes from Kyösti Mälkki |
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22 | All SMBus-related things are written by Frodo Looijaard |
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23 | SMBus 2.0 support by Mark Studebaker |
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3031 | serge | 24 | Jean Delvare |
25 | Mux support by Rodolfo Giometti |
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26 | Michael Lawnick |
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1125 | serge | 27 | |
3031 | serge | 28 | #include |
29 | #include |
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30 | #include |
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1125 | serge | 31 | #include |
32 | #include |
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33 | #include |
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34 | #include |
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35 | |||
36 | |||
3031 | serge | 37 | |
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63 | |||
64 | |||
65 | |||
66 | |||
67 | |||
68 | |||
69 | #if 0 |
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70 | |||
71 | static ssize_t |
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72 | show_modalias(struct device *dev, struct device_attribute *attr, char *buf) |
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73 | { |
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74 | struct i2c_client *client = to_i2c_client(dev); |
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75 | return sprintf(buf, "%s%s\n", I2C_MODULE_PREFIX, client->name); |
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76 | } |
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77 | |||
78 | static DEVICE_ATTR(name, S_IRUGO, show_name, NULL); |
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79 | static DEVICE_ATTR(modalias, S_IRUGO, show_modalias, NULL); |
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80 | |||
81 | static struct attribute *i2c_dev_attrs[] = { |
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82 | &dev_attr_name.attr, |
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83 | /* modalias helps coldplug: modprobe $(cat .../modalias) */ |
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84 | &dev_attr_modalias.attr, |
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85 | NULL |
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86 | }; |
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87 | |||
88 | static struct attribute_group i2c_dev_attr_group = { |
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89 | .attrs = i2c_dev_attrs, |
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90 | }; |
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91 | |||
92 | static const struct attribute_group *i2c_dev_attr_groups[] = { |
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93 | &i2c_dev_attr_group, |
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94 | NULL |
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95 | }; |
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96 | |||
97 | static const struct dev_pm_ops i2c_device_pm_ops = { |
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98 | .suspend = i2c_device_pm_suspend, |
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99 | .resume = i2c_device_pm_resume, |
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100 | .freeze = i2c_device_pm_freeze, |
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101 | .thaw = i2c_device_pm_thaw, |
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102 | .poweroff = i2c_device_pm_poweroff, |
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103 | .restore = i2c_device_pm_restore, |
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104 | SET_RUNTIME_PM_OPS( |
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105 | pm_generic_runtime_suspend, |
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106 | pm_generic_runtime_resume, |
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107 | pm_generic_runtime_idle |
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108 | ) |
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109 | }; |
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110 | |||
111 | struct bus_type i2c_bus_type = { |
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112 | .name = "i2c", |
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113 | .match = i2c_device_match, |
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114 | .probe = i2c_device_probe, |
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115 | .remove = i2c_device_remove, |
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116 | .shutdown = i2c_device_shutdown, |
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117 | .pm = &i2c_device_pm_ops, |
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118 | }; |
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119 | EXPORT_SYMBOL_GPL(i2c_bus_type); |
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120 | |||
121 | static struct device_type i2c_client_type = { |
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122 | .groups = i2c_dev_attr_groups, |
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123 | .uevent = i2c_device_uevent, |
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124 | .release = i2c_client_dev_release, |
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125 | }; |
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126 | |||
127 | |||
1125 | serge | 128 | /** |
3031 | serge | 129 | * i2c_verify_client - return parameter as i2c_client, or NULL |
130 | * @dev: device, probably from some driver model iterator |
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131 | * |
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132 | * When traversing the driver model tree, perhaps using driver model |
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133 | * iterators like @device_for_each_child(), you can't assume very much |
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134 | * about the nodes you find. Use this function to avoid oopses caused |
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135 | * by wrongly treating some non-I2C device as an i2c_client. |
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136 | */ |
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137 | struct i2c_client *i2c_verify_client(struct device *dev) |
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138 | { |
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139 | return (dev->type == &i2c_client_type) |
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140 | ? to_i2c_client(dev) |
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141 | : NULL; |
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142 | } |
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143 | EXPORT_SYMBOL(i2c_verify_client); |
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144 | |||
145 | |||
146 | /* This is a permissive address validity check, I2C address map constraints |
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147 | * are purposely not enforced, except for the general call address. */ |
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148 | static int i2c_check_client_addr_validity(const struct i2c_client *client) |
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149 | { |
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150 | if (client->flags & I2C_CLIENT_TEN) { |
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151 | /* 10-bit address, all values are valid */ |
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152 | if (client->addr > 0x3ff) |
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153 | return -EINVAL; |
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154 | } else { |
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155 | /* 7-bit address, reject the general call address */ |
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156 | if (client->addr == 0x00 || client->addr > 0x7f) |
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157 | return -EINVAL; |
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158 | } |
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159 | return 0; |
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160 | } |
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161 | |||
162 | /* And this is a strict address validity check, used when probing. If a |
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163 | * device uses a reserved address, then it shouldn't be probed. 7-bit |
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164 | * addressing is assumed, 10-bit address devices are rare and should be |
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165 | * explicitly enumerated. */ |
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166 | static int i2c_check_addr_validity(unsigned short addr) |
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167 | { |
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168 | /* |
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169 | * Reserved addresses per I2C specification: |
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170 | * 0x00 General call address / START byte |
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171 | * 0x01 CBUS address |
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172 | * 0x02 Reserved for different bus format |
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173 | * 0x03 Reserved for future purposes |
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174 | * 0x04-0x07 Hs-mode master code |
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175 | * 0x78-0x7b 10-bit slave addressing |
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176 | * 0x7c-0x7f Reserved for future purposes |
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177 | */ |
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178 | if (addr < 0x08 || addr > 0x77) |
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179 | return -EINVAL; |
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180 | return 0; |
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181 | } |
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182 | |||
183 | static int __i2c_check_addr_busy(struct device *dev, void *addrp) |
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184 | { |
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185 | struct i2c_client *client = i2c_verify_client(dev); |
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186 | int addr = *(int *)addrp; |
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187 | |||
188 | if (client && client->addr == addr) |
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189 | return -EBUSY; |
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190 | return 0; |
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191 | } |
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192 | |||
193 | /* walk up mux tree */ |
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194 | static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr) |
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195 | { |
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196 | struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter); |
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197 | int result; |
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198 | |||
199 | result = device_for_each_child(&adapter->dev, &addr, |
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200 | __i2c_check_addr_busy); |
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201 | |||
202 | if (!result && parent) |
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203 | result = i2c_check_mux_parents(parent, addr); |
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204 | |||
205 | return result; |
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206 | } |
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207 | |||
208 | /* recurse down mux tree */ |
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209 | static int i2c_check_mux_children(struct device *dev, void *addrp) |
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210 | { |
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211 | int result; |
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212 | |||
213 | if (dev->type == &i2c_adapter_type) |
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214 | result = device_for_each_child(dev, addrp, |
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215 | i2c_check_mux_children); |
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216 | else |
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217 | result = __i2c_check_addr_busy(dev, addrp); |
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218 | |||
219 | return result; |
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220 | } |
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221 | |||
222 | static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr) |
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223 | { |
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224 | struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter); |
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225 | int result = 0; |
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226 | |||
227 | if (parent) |
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228 | result = i2c_check_mux_parents(parent, addr); |
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229 | |||
230 | if (!result) |
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231 | result = device_for_each_child(&adapter->dev, &addr, |
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232 | i2c_check_mux_children); |
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233 | |||
234 | return result; |
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235 | } |
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236 | |||
237 | /** |
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238 | * i2c_lock_adapter - Get exclusive access to an I2C bus segment |
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239 | * @adapter: Target I2C bus segment |
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240 | */ |
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241 | void i2c_lock_adapter(struct i2c_adapter *adapter) |
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242 | { |
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243 | struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter); |
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244 | |||
245 | if (parent) |
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246 | i2c_lock_adapter(parent); |
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247 | else |
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248 | rt_mutex_lock(&adapter->bus_lock); |
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249 | } |
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250 | EXPORT_SYMBOL_GPL(i2c_lock_adapter); |
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251 | |||
252 | /** |
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253 | * i2c_trylock_adapter - Try to get exclusive access to an I2C bus segment |
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254 | * @adapter: Target I2C bus segment |
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255 | */ |
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256 | static int i2c_trylock_adapter(struct i2c_adapter *adapter) |
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257 | { |
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258 | struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter); |
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259 | |||
260 | if (parent) |
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261 | return i2c_trylock_adapter(parent); |
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262 | else |
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263 | return rt_mutex_trylock(&adapter->bus_lock); |
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264 | } |
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265 | |||
266 | /** |
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267 | * i2c_unlock_adapter - Release exclusive access to an I2C bus segment |
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268 | * @adapter: Target I2C bus segment |
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269 | */ |
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270 | void i2c_unlock_adapter(struct i2c_adapter *adapter) |
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271 | { |
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272 | struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter); |
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273 | |||
274 | if (parent) |
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275 | i2c_unlock_adapter(parent); |
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276 | else |
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277 | rt_mutex_unlock(&adapter->bus_lock); |
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278 | } |
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279 | EXPORT_SYMBOL_GPL(i2c_unlock_adapter); |
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280 | |||
281 | #endif |
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282 | |||
283 | |||
284 | /** |
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1125 | serge | 285 | * i2c_transfer - execute a single or combined I2C message |
286 | * @adap: Handle to I2C bus |
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287 | * @msgs: One or more messages to execute before STOP is issued to |
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288 | * terminate the operation; each message begins with a START. |
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289 | * @num: Number of messages to be executed. |
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290 | * |
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291 | * Returns negative errno, else the number of messages executed. |
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292 | * |
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293 | * Note that there is no requirement that each message be sent to |
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294 | * the same slave address, although that is the most common model. |
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295 | */ |
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296 | int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) |
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297 | { |
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298 | unsigned long orig_jiffies; |
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299 | int ret, try; |
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300 | |||
301 | /* REVISIT the fault reporting model here is weak: |
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302 | * |
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303 | * - When we get an error after receiving N bytes from a slave, |
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304 | * there is no way to report "N". |
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305 | * |
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306 | * - When we get a NAK after transmitting N bytes to a slave, |
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307 | * there is no way to report "N" ... or to let the master |
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308 | * continue executing the rest of this combined message, if |
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309 | * that's the appropriate response. |
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310 | * |
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311 | * - When for example "num" is two and we successfully complete |
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312 | * the first message but get an error part way through the |
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313 | * second, it's unclear whether that should be reported as |
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314 | * one (discarding status on the second message) or errno |
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315 | * (discarding status on the first one). |
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316 | */ |
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317 | |||
318 | if (adap->algo->master_xfer) { |
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319 | |||
3031 | serge | 320 | /* Retry automatically on arbitration loss */ |
321 | orig_jiffies = GetTimerTicks(); |
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1125 | serge | 322 | |
323 | for (ret = 0, try = 0; try <= adap->retries; try++) { |
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1963 | serge | 324 | |
1125 | serge | 325 | ret = adap->algo->master_xfer(adap, msgs, num); |
326 | if (ret != -EAGAIN) |
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327 | break; |
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3031 | serge | 328 | |
329 | if (time_after(GetTimerTicks(), orig_jiffies + adap->timeout)) |
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330 | break; |
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331 | |||
332 | delay(1); |
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1125 | serge | 333 | } |
334 | // mutex_unlock(&adap->bus_lock); |
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335 | return ret; |
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336 | } else { |
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3031 | serge | 337 | dbgprintf("I2C level transfers not supported\n"); |
1125 | serge | 338 | return -EOPNOTSUPP; |
339 | } |
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340 | } |
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341 | EXPORT_SYMBOL(i2c_transfer); |
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342 | |||
343 | |||
1963 | serge | 344 | /** |
345 | * i2c_new_device - instantiate an i2c device |
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346 | * @adap: the adapter managing the device |
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347 | * @info: describes one I2C device; bus_num is ignored |
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348 | * Context: can sleep |
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349 | * |
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350 | * Create an i2c device. Binding is handled through driver model |
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351 | * probe()/remove() methods. A driver may be bound to this device when we |
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352 | * return from this function, or any later moment (e.g. maybe hotplugging will |
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353 | * load the driver module). This call is not appropriate for use by mainboard |
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354 | * initialization logic, which usually runs during an arch_initcall() long |
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355 | * before any i2c_adapter could exist. |
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356 | * |
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357 | * This returns the new i2c client, which may be saved for later use with |
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358 | * i2c_unregister_device(); or NULL to indicate an error. |
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359 | */ |
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360 | struct i2c_client * |
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361 | i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info) |
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362 | { |
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363 | struct i2c_client *client; |
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364 | int status; |
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1125 | serge | 365 | |
1963 | serge | 366 | client = kzalloc(sizeof *client, GFP_KERNEL); |
367 | if (!client) |
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368 | return NULL; |
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1125 | serge | 369 | |
1963 | serge | 370 | client->adapter = adap; |
1125 | serge | 371 | |
1963 | serge | 372 | client->flags = info->flags; |
373 | client->addr = info->addr; |
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374 | client->irq = info->irq; |
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375 | |||
376 | strlcpy(client->name, info->type, sizeof(client->name)); |
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377 | |||
378 | return client; |
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379 | }=>> |
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380 |