diff options
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/feature-removal-schedule.txt | 10 | ||||
-rw-r--r-- | Documentation/i2c/instantiating-devices | 44 | ||||
-rw-r--r-- | Documentation/i2c/writing-clients | 16 |
3 files changed, 47 insertions, 23 deletions
diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt index 8d07ed31207e..f8cd450be9aa 100644 --- a/Documentation/feature-removal-schedule.txt +++ b/Documentation/feature-removal-schedule.txt | |||
@@ -368,16 +368,6 @@ Who: Krzysztof Piotr Oledzki <ole@ans.pl> | |||
368 | 368 | ||
369 | --------------------------- | 369 | --------------------------- |
370 | 370 | ||
371 | What: i2c_attach_client(), i2c_detach_client(), i2c_driver->detach_client(), | ||
372 | i2c_adapter->client_register(), i2c_adapter->client_unregister | ||
373 | When: 2.6.30 | ||
374 | Check: i2c_attach_client i2c_detach_client | ||
375 | Why: Deprecated by the new (standard) device driver binding model. Use | ||
376 | i2c_driver->probe() and ->remove() instead. | ||
377 | Who: Jean Delvare <khali@linux-fr.org> | ||
378 | |||
379 | --------------------------- | ||
380 | |||
381 | What: fscher and fscpos drivers | 371 | What: fscher and fscpos drivers |
382 | When: June 2009 | 372 | When: June 2009 |
383 | Why: Deprecated by the new fschmd driver. | 373 | Why: Deprecated by the new fschmd driver. |
diff --git a/Documentation/i2c/instantiating-devices b/Documentation/i2c/instantiating-devices index b55ce57a84db..c740b7b41088 100644 --- a/Documentation/i2c/instantiating-devices +++ b/Documentation/i2c/instantiating-devices | |||
@@ -165,3 +165,47 @@ was done there. Two significant differences are: | |||
165 | Once again, method 3 should be avoided wherever possible. Explicit device | 165 | Once again, method 3 should be avoided wherever possible. Explicit device |
166 | instantiation (methods 1 and 2) is much preferred for it is safer and | 166 | instantiation (methods 1 and 2) is much preferred for it is safer and |
167 | faster. | 167 | faster. |
168 | |||
169 | |||
170 | Method 4: Instantiate from user-space | ||
171 | ------------------------------------- | ||
172 | |||
173 | In general, the kernel should know which I2C devices are connected and | ||
174 | what addresses they live at. However, in certain cases, it does not, so a | ||
175 | sysfs interface was added to let the user provide the information. This | ||
176 | interface is made of 2 attribute files which are created in every I2C bus | ||
177 | directory: new_device and delete_device. Both files are write only and you | ||
178 | must write the right parameters to them in order to properly instantiate, | ||
179 | respectively delete, an I2C device. | ||
180 | |||
181 | File new_device takes 2 parameters: the name of the I2C device (a string) | ||
182 | and the address of the I2C device (a number, typically expressed in | ||
183 | hexadecimal starting with 0x, but can also be expressed in decimal.) | ||
184 | |||
185 | File delete_device takes a single parameter: the address of the I2C | ||
186 | device. As no two devices can live at the same address on a given I2C | ||
187 | segment, the address is sufficient to uniquely identify the device to be | ||
188 | deleted. | ||
189 | |||
190 | Example: | ||
191 | # echo eeprom 0x50 > /sys/class/i2c-adapter/i2c-3/new_device | ||
192 | |||
193 | While this interface should only be used when in-kernel device declaration | ||
194 | can't be done, there is a variety of cases where it can be helpful: | ||
195 | * The I2C driver usually detects devices (method 3 above) but the bus | ||
196 | segment your device lives on doesn't have the proper class bit set and | ||
197 | thus detection doesn't trigger. | ||
198 | * The I2C driver usually detects devices, but your device lives at an | ||
199 | unexpected address. | ||
200 | * The I2C driver usually detects devices, but your device is not detected, | ||
201 | either because the detection routine is too strict, or because your | ||
202 | device is not officially supported yet but you know it is compatible. | ||
203 | * You are developing a driver on a test board, where you soldered the I2C | ||
204 | device yourself. | ||
205 | |||
206 | This interface is a replacement for the force_* module parameters some I2C | ||
207 | drivers implement. Being implemented in i2c-core rather than in each | ||
208 | device driver individually, it is much more efficient, and also has the | ||
209 | advantage that you do not have to reload the driver to change a setting. | ||
210 | You can also instantiate the device before the driver is loaded or even | ||
211 | available, and you don't need to know what driver the device needs. | ||
diff --git a/Documentation/i2c/writing-clients b/Documentation/i2c/writing-clients index c1a06f989cf7..7860aafb483d 100644 --- a/Documentation/i2c/writing-clients +++ b/Documentation/i2c/writing-clients | |||
@@ -126,19 +126,9 @@ different) configuration information, as do drivers handling chip variants | |||
126 | that can't be distinguished by protocol probing, or which need some board | 126 | that can't be distinguished by protocol probing, or which need some board |
127 | specific information to operate correctly. | 127 | specific information to operate correctly. |
128 | 128 | ||
129 | Accordingly, the I2C stack now has two models for associating I2C devices | ||
130 | with their drivers: the original "legacy" model, and a newer one that's | ||
131 | fully compatible with the Linux 2.6 driver model. These models do not mix, | ||
132 | since the "legacy" model requires drivers to create "i2c_client" device | ||
133 | objects after SMBus style probing, while the Linux driver model expects | ||
134 | drivers to be given such device objects in their probe() routines. | ||
135 | 129 | ||
136 | The legacy model is deprecated now and will soon be removed, so we no | 130 | Device/Driver Binding |
137 | longer document it here. | 131 | --------------------- |
138 | |||
139 | |||
140 | Standard Driver Model Binding ("New Style") | ||
141 | ------------------------------------------- | ||
142 | 132 | ||
143 | System infrastructure, typically board-specific initialization code or | 133 | System infrastructure, typically board-specific initialization code or |
144 | boot firmware, reports what I2C devices exist. For example, there may be | 134 | boot firmware, reports what I2C devices exist. For example, there may be |
@@ -201,7 +191,7 @@ a given I2C bus. This is for example the case of hardware monitoring | |||
201 | devices on a PC's SMBus. In that case, you may want to let your driver | 191 | devices on a PC's SMBus. In that case, you may want to let your driver |
202 | detect supported devices automatically. This is how the legacy model | 192 | detect supported devices automatically. This is how the legacy model |
203 | was working, and is now available as an extension to the standard | 193 | was working, and is now available as an extension to the standard |
204 | driver model (so that we can finally get rid of the legacy model.) | 194 | driver model. |
205 | 195 | ||
206 | You simply have to define a detect callback which will attempt to | 196 | You simply have to define a detect callback which will attempt to |
207 | identify supported devices (returning 0 for supported ones and -ENODEV | 197 | identify supported devices (returning 0 for supported ones and -ENODEV |