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Merge branch 'i2c-for-linus' of git://aeryn.fluff.org.uk/bjdooks/linux
* 'i2c-for-linus' of git://aeryn.fluff.org.uk/bjdooks/linux: i2c: Blackfin I2C Driver: Functional power management support i2c: Documentation: upgrading clients HOWTO i2c: S3C24XX I2C frequency scaling support. i2c: i2c_gpio: keep probe resident for hotplugged devices. i2c: S3C2410: Pass the I2C bus number via drivers platform data
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,281 @@ | ||
| Upgrading I2C Drivers to the new 2.6 Driver Model | ||
| ================================================= | ||
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| Ben Dooks <ben-linux@fluff.org> | ||
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| Introduction | ||
| ------------ | ||
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| This guide outlines how to alter existing Linux 2.6 client drivers from | ||
| the old to the new new binding methods. | ||
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| Example old-style driver | ||
| ------------------------ | ||
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| struct example_state { | ||
| struct i2c_client client; | ||
| .... | ||
| }; | ||
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| static struct i2c_driver example_driver; | ||
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| static unsigned short ignore[] = { I2C_CLIENT_END }; | ||
| static unsigned short normal_addr[] = { OUR_ADDR, I2C_CLIENT_END }; | ||
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| I2C_CLIENT_INSMOD; | ||
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| static int example_attach(struct i2c_adapter *adap, int addr, int kind) | ||
| { | ||
| struct example_state *state; | ||
| struct device *dev = &adap->dev; /* to use for dev_ reports */ | ||
| int ret; | ||
|
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| state = kzalloc(sizeof(struct example_state), GFP_KERNEL); | ||
| if (state == NULL) { | ||
| dev_err(dev, "failed to create our state\n"); | ||
| return -ENOMEM; | ||
| } | ||
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| example->client.addr = addr; | ||
| example->client.flags = 0; | ||
| example->client.adapter = adap; | ||
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| i2c_set_clientdata(&state->i2c_client, state); | ||
| strlcpy(client->i2c_client.name, "example", I2C_NAME_SIZE); | ||
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| ret = i2c_attach_client(&state->i2c_client); | ||
| if (ret < 0) { | ||
| dev_err(dev, "failed to attach client\n"); | ||
| kfree(state); | ||
| return ret; | ||
| } | ||
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| dev = &state->i2c_client.dev; | ||
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| /* rest of the initialisation goes here. */ | ||
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| dev_info(dev, "example client created\n"); | ||
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| return 0; | ||
| } | ||
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| static int __devexit example_detach(struct i2c_client *client) | ||
| { | ||
| struct example_state *state = i2c_get_clientdata(client); | ||
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| i2c_detach_client(client); | ||
| kfree(state); | ||
| return 0; | ||
| } | ||
|
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| static int example_attach_adapter(struct i2c_adapter *adap) | ||
| { | ||
| return i2c_probe(adap, &addr_data, example_attach); | ||
| } | ||
|
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| static struct i2c_driver example_driver = { | ||
| .driver = { | ||
| .owner = THIS_MODULE, | ||
| .name = "example", | ||
| }, | ||
| .attach_adapter = example_attach_adapter, | ||
| .detach_client = __devexit_p(example_detach), | ||
| .suspend = example_suspend, | ||
| .resume = example_resume, | ||
| }; | ||
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| Updating the client | ||
| ------------------- | ||
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| The new style binding model will check against a list of supported | ||
| devices and their associated address supplied by the code registering | ||
| the busses. This means that the driver .attach_adapter and | ||
| .detach_adapter methods can be removed, along with the addr_data, | ||
| as follows: | ||
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| - static struct i2c_driver example_driver; | ||
|
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| - static unsigned short ignore[] = { I2C_CLIENT_END }; | ||
| - static unsigned short normal_addr[] = { OUR_ADDR, I2C_CLIENT_END }; | ||
|
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| - I2C_CLIENT_INSMOD; | ||
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| - static int example_attach_adapter(struct i2c_adapter *adap) | ||
| - { | ||
| - return i2c_probe(adap, &addr_data, example_attach); | ||
| - } | ||
|
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| static struct i2c_driver example_driver = { | ||
| - .attach_adapter = example_attach_adapter, | ||
| - .detach_client = __devexit_p(example_detach), | ||
| } | ||
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| Add the probe and remove methods to the i2c_driver, as so: | ||
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| static struct i2c_driver example_driver = { | ||
| + .probe = example_probe, | ||
| + .remove = __devexit_p(example_remove), | ||
| } | ||
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| Change the example_attach method to accept the new parameters | ||
| which include the i2c_client that it will be working with: | ||
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| - static int example_attach(struct i2c_adapter *adap, int addr, int kind) | ||
| + static int example_probe(struct i2c_client *client, | ||
| + const struct i2c_device_id *id) | ||
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| Change the name of example_attach to example_probe to align it with the | ||
| i2c_driver entry names. The rest of the probe routine will now need to be | ||
| changed as the i2c_client has already been setup for use. | ||
|
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| The necessary client fields have already been setup before | ||
| the probe function is called, so the following client setup | ||
| can be removed: | ||
|
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| - example->client.addr = addr; | ||
| - example->client.flags = 0; | ||
| - example->client.adapter = adap; | ||
| - | ||
| - strlcpy(client->i2c_client.name, "example", I2C_NAME_SIZE); | ||
|
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| The i2c_set_clientdata is now: | ||
|
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| - i2c_set_clientdata(&state->client, state); | ||
| + i2c_set_clientdata(client, state); | ||
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| The call to i2c_attach_client is no longer needed, if the probe | ||
| routine exits successfully, then the driver will be automatically | ||
| attached by the core. Change the probe routine as so: | ||
|
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| - ret = i2c_attach_client(&state->i2c_client); | ||
| - if (ret < 0) { | ||
| - dev_err(dev, "failed to attach client\n"); | ||
| - kfree(state); | ||
| - return ret; | ||
| - } | ||
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| Remove the storage of 'struct i2c_client' from the 'struct example_state' | ||
| as we are provided with the i2c_client in our example_probe. Instead we | ||
| store a pointer to it for when it is needed. | ||
|
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| struct example_state { | ||
| - struct i2c_client client; | ||
| + struct i2c_client *client; | ||
|
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| the new i2c client as so: | ||
|
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| - struct device *dev = &adap->dev; /* to use for dev_ reports */ | ||
| + struct device *dev = &i2c_client->dev; /* to use for dev_ reports */ | ||
|
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| And remove the change after our client is attached, as the driver no | ||
| longer needs to register a new client structure with the core: | ||
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| - dev = &state->i2c_client.dev; | ||
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| In the probe routine, ensure that the new state has the client stored | ||
| in it: | ||
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| static int example_probe(struct i2c_client *i2c_client, | ||
| const struct i2c_device_id *id) | ||
| { | ||
| struct example_state *state; | ||
| struct device *dev = &i2c_client->dev; | ||
| int ret; | ||
|
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| state = kzalloc(sizeof(struct example_state), GFP_KERNEL); | ||
| if (state == NULL) { | ||
| dev_err(dev, "failed to create our state\n"); | ||
| return -ENOMEM; | ||
| } | ||
|
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| + state->client = i2c_client; | ||
|
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| Update the detach method, by changing the name to _remove and | ||
| to delete the i2c_detach_client call. It is possible that you | ||
| can also remove the ret variable as it is not not needed for | ||
| any of the core functions. | ||
|
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| - static int __devexit example_detach(struct i2c_client *client) | ||
| + static int __devexit example_remove(struct i2c_client *client) | ||
| { | ||
| struct example_state *state = i2c_get_clientdata(client); | ||
|
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| - i2c_detach_client(client); | ||
|
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| And finally ensure that we have the correct ID table for the i2c-core | ||
| and other utilities: | ||
|
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| + struct i2c_device_id example_idtable[] = { | ||
| + { "example", 0 }, | ||
| + { } | ||
| +}; | ||
| + | ||
| +MODULE_DEVICE_TABLE(i2c, example_idtable); | ||
|
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| static struct i2c_driver example_driver = { | ||
| .driver = { | ||
| .owner = THIS_MODULE, | ||
| .name = "example", | ||
| }, | ||
| + .id_table = example_ids, | ||
|
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| Our driver should now look like this: | ||
|
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| struct example_state { | ||
| struct i2c_client *client; | ||
| .... | ||
| }; | ||
|
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| static int example_probe(struct i2c_client *client, | ||
| const struct i2c_device_id *id) | ||
| { | ||
| struct example_state *state; | ||
| struct device *dev = &client->dev; | ||
|
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| state = kzalloc(sizeof(struct example_state), GFP_KERNEL); | ||
| if (state == NULL) { | ||
| dev_err(dev, "failed to create our state\n"); | ||
| return -ENOMEM; | ||
| } | ||
|
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| state->client = client; | ||
| i2c_set_clientdata(client, state); | ||
|
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| /* rest of the initialisation goes here. */ | ||
|
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| dev_info(dev, "example client created\n"); | ||
|
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| return 0; | ||
| } | ||
|
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| static int __devexit example_remove(struct i2c_client *client) | ||
| { | ||
| struct example_state *state = i2c_get_clientdata(client); | ||
|
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| kfree(state); | ||
| return 0; | ||
| } | ||
|
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| static struct i2c_device_id example_idtable[] = { | ||
| { "example", 0 }, | ||
| { } | ||
| }; | ||
|
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| MODULE_DEVICE_TABLE(i2c, example_idtable); | ||
|
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| static struct i2c_driver example_driver = { | ||
| .driver = { | ||
| .owner = THIS_MODULE, | ||
| .name = "example", | ||
| }, | ||
| .id_table = example_idtable, | ||
| .probe = example_probe, | ||
| .remove = __devexit_p(example_remove), | ||
| .suspend = example_suspend, | ||
| .resume = example_resume, | ||
| }; |
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