[PATCH v2] docs: remove the 2.6 "Upgrading I2C Drivers" guide

Stephen Kitt
2020-08-06T16:52:53Z

All the drivers have long since been upgraded, and all the important
information here is also included in the "Implementing I2C device
drivers" guide.

Signed-off-by: Stephen Kitt <steve@sk2.org>
---
Documentation/i2c/index.rst | 1 -
Documentation/i2c/upgrading-clients.rst | 285 ------------------------
2 files changed, 286 deletions(-)
delete mode 100644 Documentation/i2c/upgrading-clients.rst

diff --git a/Documentation/i2c/index.rst b/Documentation/i2c/index.rst
index fee4744475df..8a2ad3845191 100644
--- a/Documentation/i2c/index.rst
+++ b/Documentation/i2c/index.rst
@@ -62,7 +62,6 @@ Legacy documentation
.. toctree::
:maxdepth: 1

- upgrading-clients
old-module-parameters

.. only:: subproject and html
diff --git a/Documentation/i2c/upgrading-clients.rst b/Documentation/i2c/upgrading-clients.rst
deleted file mode 100644
index 1708090d7b8f..000000000000
--- a/Documentation/i2c/upgrading-clients.rst
+++ /dev/null
@@ -1,285 +0,0 @@
-=================================================
-Upgrading I2C Drivers to the new 2.6 Driver Model
-=================================================
-
-Ben Dooks <ben-linux@fluff.org>
-
-Introduction
-------------
-
-This guide outlines how to alter existing Linux 2.6 client drivers from
-the old to the new binding methods.
-
-
-Example old-style driver
-------------------------
-
-::
-
- struct example_state {
- struct i2c_client client;
- ....
- };
-
- static struct i2c_driver example_driver;
-
- static unsigned short ignore[] = { I2C_CLIENT_END };
- static unsigned short normal_addr[] = { OUR_ADDR, I2C_CLIENT_END };
-
- I2C_CLIENT_INSMOD;
-
- 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;
-
- state = kzalloc(sizeof(struct example_state), GFP_KERNEL);
- if (state == NULL) {
- dev_err(dev, "failed to create our state\n");
- return -ENOMEM;
- }
-
- example->client.addr = addr;
- example->client.flags = 0;
- example->client.adapter = adap;
-
- i2c_set_clientdata(&state->i2c_client, state);
- strscpy(client->i2c_client.name, "example", sizeof(client->i2c_client.name));
-
- ret = i2c_attach_client(&state->i2c_client);
- if (ret < 0) {
- dev_err(dev, "failed to attach client\n");
- kfree(state);
- return ret;
- }
-
- dev = &state->i2c_client.dev;
-
- /* rest of the initialisation goes here. */
-
- dev_info(dev, "example client created\n");
-
- return 0;
- }
-
- static int example_detach(struct i2c_client *client)
- {
- struct example_state *state = i2c_get_clientdata(client);
-
- i2c_detach_client(client);
- kfree(state);
- return 0;
- }
-
- static int example_attach_adapter(struct i2c_adapter *adap)
- {
- return i2c_probe(adap, &addr_data, example_attach);
- }
-
- static struct i2c_driver example_driver = {
- .driver = {
- .owner = THIS_MODULE,
- .name = "example",
- .pm = &example_pm_ops,
- },
- .attach_adapter = example_attach_adapter,
- .detach_client = example_detach,
- };
-
-
-Updating the client
--------------------
-
-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_client methods can be removed, along with the addr_data,
-as follows::
-
- - static struct i2c_driver example_driver;
-
- - static unsigned short ignore[] = { I2C_CLIENT_END };
- - static unsigned short normal_addr[] = { OUR_ADDR, I2C_CLIENT_END };
-
- - I2C_CLIENT_INSMOD;
-
- - static int example_attach_adapter(struct i2c_adapter *adap)
- - {
- - return i2c_probe(adap, &addr_data, example_attach);
- - }
-
- static struct i2c_driver example_driver = {
- - .attach_adapter = example_attach_adapter,
- - .detach_client = example_detach,
- }
-
-Add the probe and remove methods to the i2c_driver, as so::
-
- static struct i2c_driver example_driver = {
- + .probe = example_probe,
- + .remove = example_remove,
- }
-
-Change the example_attach method to accept the new parameters
-which include the i2c_client that it will be working with::
-
- - 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)
-
-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.
-
-The necessary client fields have already been setup before
-the probe function is called, so the following client setup
-can be removed::
-
- - example->client.addr = addr;
- - example->client.flags = 0;
- - example->client.adapter = adap;
- -
- - strscpy(client->i2c_client.name, "example", sizeof(client->i2c_client.name));
-
-The i2c_set_clientdata is now::
-
- - i2c_set_clientdata(&state->client, state);
- + i2c_set_clientdata(client, state);
-
-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::
-
- - ret = i2c_attach_client(&state->i2c_client);
- - if (ret < 0) {
- - dev_err(dev, "failed to attach client\n");
- - kfree(state);
- - return ret;
- - }
-
-
-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.
-
-::
-
- struct example_state {
- - struct i2c_client client;
- + struct i2c_client *client;
-
-the new i2c client as so::
-
- - struct device *dev = &adap->dev; /* to use for dev_ reports */
- + struct device *dev = &i2c_client->dev; /* to use for dev_ reports */
-
-And remove the change after our client is attached, as the driver no
-longer needs to register a new client structure with the core::
-
- - dev = &state->i2c_client.dev;
-
-In the probe routine, ensure that the new state has the client stored
-in it::
-
- 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;
-
- state = kzalloc(sizeof(struct example_state), GFP_KERNEL);
- if (state == NULL) {
- dev_err(dev, "failed to create our state\n");
- return -ENOMEM;
- }
-
- + state->client = i2c_client;
-
-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 needed for any
-of the core functions.
-
-::
-
- - static int example_detach(struct i2c_client *client)
- + static int example_remove(struct i2c_client *client)
- {
- struct example_state *state = i2c_get_clientdata(client);
-
- - i2c_detach_client(client);
-
-And finally ensure that we have the correct ID table for the i2c-core
-and other utilities::
-
- + struct i2c_device_id example_idtable[] = {
- + { "example", 0 },
- + { }
- +};
- +
- +MODULE_DEVICE_TABLE(i2c, example_idtable);
-
- static struct i2c_driver example_driver = {
- .driver = {
- .owner = THIS_MODULE,
- .name = "example",
- },
- + .id_table = example_ids,
-
-
-Our driver should now look like this::
-
- struct example_state {
- struct i2c_client *client;
- ....
- };
-
- static int example_probe(struct i2c_client *client,
- const struct i2c_device_id *id)
- {
- struct example_state *state;
- struct device *dev = &client->dev;
-
- state = kzalloc(sizeof(struct example_state), GFP_KERNEL);
- if (state == NULL) {
- dev_err(dev, "failed to create our state\n");
- return -ENOMEM;
- }
-
- state->client = client;
- i2c_set_clientdata(client, state);
-
- /* rest of the initialisation goes here. */
-
- dev_info(dev, "example client created\n");
-
- return 0;
- }
-
- static int example_remove(struct i2c_client *client)
- {
- struct example_state *state = i2c_get_clientdata(client);
-
- kfree(state);
- return 0;
- }
-
- static struct i2c_device_id example_idtable[] = {
- { "example", 0 },
- { }
- };
-
- MODULE_DEVICE_TABLE(i2c, example_idtable);
-
- static struct i2c_driver example_driver = {
- .driver = {
- .owner = THIS_MODULE,
- .name = "example",
- .pm = &example_pm_ops,
- },
- .id_table = example_idtable,
- .probe = example_probe,
- .remove = example_remove,
- };

base-commit: 2324d50d051ec0f14a548e78554fb02513d6dcef
--
2.20.1