diff options
author | Ingo Molnar <mingo@elte.hu> | 2008-07-30 13:33:48 -0400 |
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committer | Ingo Molnar <mingo@elte.hu> | 2008-07-30 13:33:48 -0400 |
commit | 15dd859cacf312f606f54502d1f66537a1e5c78c (patch) | |
tree | e50e125eaa6da83fa715704e53c1bde013d1ef8e /Documentation/i2c/upgrading-clients | |
parent | b2d9d33412b9d13a40cd314d93ab517950fc5950 (diff) | |
parent | 6e86841d05f371b5b9b86ce76c02aaee83352298 (diff) |
Merge commit 'v2.6.27-rc1' into x86/core
Conflicts:
include/asm-x86/dma-mapping.h
include/asm-x86/namei.h
include/asm-x86/uaccess.h
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'Documentation/i2c/upgrading-clients')
-rw-r--r-- | Documentation/i2c/upgrading-clients | 281 |
1 files changed, 281 insertions, 0 deletions
diff --git a/Documentation/i2c/upgrading-clients b/Documentation/i2c/upgrading-clients new file mode 100644 index 000000000000..9a45f9bb6a25 --- /dev/null +++ b/Documentation/i2c/upgrading-clients | |||
@@ -0,0 +1,281 @@ | |||
1 | Upgrading I2C Drivers to the new 2.6 Driver Model | ||
2 | ================================================= | ||
3 | |||
4 | Ben Dooks <ben-linux@fluff.org> | ||
5 | |||
6 | Introduction | ||
7 | ------------ | ||
8 | |||
9 | This guide outlines how to alter existing Linux 2.6 client drivers from | ||
10 | the old to the new new binding methods. | ||
11 | |||
12 | |||
13 | Example old-style driver | ||
14 | ------------------------ | ||
15 | |||
16 | |||
17 | struct example_state { | ||
18 | struct i2c_client client; | ||
19 | .... | ||
20 | }; | ||
21 | |||
22 | static struct i2c_driver example_driver; | ||
23 | |||
24 | static unsigned short ignore[] = { I2C_CLIENT_END }; | ||
25 | static unsigned short normal_addr[] = { OUR_ADDR, I2C_CLIENT_END }; | ||
26 | |||
27 | I2C_CLIENT_INSMOD; | ||
28 | |||
29 | static int example_attach(struct i2c_adapter *adap, int addr, int kind) | ||
30 | { | ||
31 | struct example_state *state; | ||
32 | struct device *dev = &adap->dev; /* to use for dev_ reports */ | ||
33 | int ret; | ||
34 | |||
35 | state = kzalloc(sizeof(struct example_state), GFP_KERNEL); | ||
36 | if (state == NULL) { | ||
37 | dev_err(dev, "failed to create our state\n"); | ||
38 | return -ENOMEM; | ||
39 | } | ||
40 | |||
41 | example->client.addr = addr; | ||
42 | example->client.flags = 0; | ||
43 | example->client.adapter = adap; | ||
44 | |||
45 | i2c_set_clientdata(&state->i2c_client, state); | ||
46 | strlcpy(client->i2c_client.name, "example", I2C_NAME_SIZE); | ||
47 | |||
48 | ret = i2c_attach_client(&state->i2c_client); | ||
49 | if (ret < 0) { | ||
50 | dev_err(dev, "failed to attach client\n"); | ||
51 | kfree(state); | ||
52 | return ret; | ||
53 | } | ||
54 | |||
55 | dev = &state->i2c_client.dev; | ||
56 | |||
57 | /* rest of the initialisation goes here. */ | ||
58 | |||
59 | dev_info(dev, "example client created\n"); | ||
60 | |||
61 | return 0; | ||
62 | } | ||
63 | |||
64 | static int __devexit example_detach(struct i2c_client *client) | ||
65 | { | ||
66 | struct example_state *state = i2c_get_clientdata(client); | ||
67 | |||
68 | i2c_detach_client(client); | ||
69 | kfree(state); | ||
70 | return 0; | ||
71 | } | ||
72 | |||
73 | static int example_attach_adapter(struct i2c_adapter *adap) | ||
74 | { | ||
75 | return i2c_probe(adap, &addr_data, example_attach); | ||
76 | } | ||
77 | |||
78 | static struct i2c_driver example_driver = { | ||
79 | .driver = { | ||
80 | .owner = THIS_MODULE, | ||
81 | .name = "example", | ||
82 | }, | ||
83 | .attach_adapter = example_attach_adapter, | ||
84 | .detach_client = __devexit_p(example_detach), | ||
85 | .suspend = example_suspend, | ||
86 | .resume = example_resume, | ||
87 | }; | ||
88 | |||
89 | |||
90 | Updating the client | ||
91 | ------------------- | ||
92 | |||
93 | The new style binding model will check against a list of supported | ||
94 | devices and their associated address supplied by the code registering | ||
95 | the busses. This means that the driver .attach_adapter and | ||
96 | .detach_adapter methods can be removed, along with the addr_data, | ||
97 | as follows: | ||
98 | |||
99 | - static struct i2c_driver example_driver; | ||
100 | |||
101 | - static unsigned short ignore[] = { I2C_CLIENT_END }; | ||
102 | - static unsigned short normal_addr[] = { OUR_ADDR, I2C_CLIENT_END }; | ||
103 | |||
104 | - I2C_CLIENT_INSMOD; | ||
105 | |||
106 | - static int example_attach_adapter(struct i2c_adapter *adap) | ||
107 | - { | ||
108 | - return i2c_probe(adap, &addr_data, example_attach); | ||
109 | - } | ||
110 | |||
111 | static struct i2c_driver example_driver = { | ||
112 | - .attach_adapter = example_attach_adapter, | ||
113 | - .detach_client = __devexit_p(example_detach), | ||
114 | } | ||
115 | |||
116 | Add the probe and remove methods to the i2c_driver, as so: | ||
117 | |||
118 | static struct i2c_driver example_driver = { | ||
119 | + .probe = example_probe, | ||
120 | + .remove = __devexit_p(example_remove), | ||
121 | } | ||
122 | |||
123 | Change the example_attach method to accept the new parameters | ||
124 | which include the i2c_client that it will be working with: | ||
125 | |||
126 | - static int example_attach(struct i2c_adapter *adap, int addr, int kind) | ||
127 | + static int example_probe(struct i2c_client *client, | ||
128 | + const struct i2c_device_id *id) | ||
129 | |||
130 | Change the name of example_attach to example_probe to align it with the | ||
131 | i2c_driver entry names. The rest of the probe routine will now need to be | ||
132 | changed as the i2c_client has already been setup for use. | ||
133 | |||
134 | The necessary client fields have already been setup before | ||
135 | the probe function is called, so the following client setup | ||
136 | can be removed: | ||
137 | |||
138 | - example->client.addr = addr; | ||
139 | - example->client.flags = 0; | ||
140 | - example->client.adapter = adap; | ||
141 | - | ||
142 | - strlcpy(client->i2c_client.name, "example", I2C_NAME_SIZE); | ||
143 | |||
144 | The i2c_set_clientdata is now: | ||
145 | |||
146 | - i2c_set_clientdata(&state->client, state); | ||
147 | + i2c_set_clientdata(client, state); | ||
148 | |||
149 | The call to i2c_attach_client is no longer needed, if the probe | ||
150 | routine exits successfully, then the driver will be automatically | ||
151 | attached by the core. Change the probe routine as so: | ||
152 | |||
153 | - ret = i2c_attach_client(&state->i2c_client); | ||
154 | - if (ret < 0) { | ||
155 | - dev_err(dev, "failed to attach client\n"); | ||
156 | - kfree(state); | ||
157 | - return ret; | ||
158 | - } | ||
159 | |||
160 | |||
161 | Remove the storage of 'struct i2c_client' from the 'struct example_state' | ||
162 | as we are provided with the i2c_client in our example_probe. Instead we | ||
163 | store a pointer to it for when it is needed. | ||
164 | |||
165 | struct example_state { | ||
166 | - struct i2c_client client; | ||
167 | + struct i2c_client *client; | ||
168 | |||
169 | the new i2c client as so: | ||
170 | |||
171 | - struct device *dev = &adap->dev; /* to use for dev_ reports */ | ||
172 | + struct device *dev = &i2c_client->dev; /* to use for dev_ reports */ | ||
173 | |||
174 | And remove the change after our client is attached, as the driver no | ||
175 | longer needs to register a new client structure with the core: | ||
176 | |||
177 | - dev = &state->i2c_client.dev; | ||
178 | |||
179 | In the probe routine, ensure that the new state has the client stored | ||
180 | in it: | ||
181 | |||
182 | static int example_probe(struct i2c_client *i2c_client, | ||
183 | const struct i2c_device_id *id) | ||
184 | { | ||
185 | struct example_state *state; | ||
186 | struct device *dev = &i2c_client->dev; | ||
187 | int ret; | ||
188 | |||
189 | state = kzalloc(sizeof(struct example_state), GFP_KERNEL); | ||
190 | if (state == NULL) { | ||
191 | dev_err(dev, "failed to create our state\n"); | ||
192 | return -ENOMEM; | ||
193 | } | ||
194 | |||
195 | + state->client = i2c_client; | ||
196 | |||
197 | Update the detach method, by changing the name to _remove and | ||
198 | to delete the i2c_detach_client call. It is possible that you | ||
199 | can also remove the ret variable as it is not not needed for | ||
200 | any of the core functions. | ||
201 | |||
202 | - static int __devexit example_detach(struct i2c_client *client) | ||
203 | + static int __devexit example_remove(struct i2c_client *client) | ||
204 | { | ||
205 | struct example_state *state = i2c_get_clientdata(client); | ||
206 | |||
207 | - i2c_detach_client(client); | ||
208 | |||
209 | And finally ensure that we have the correct ID table for the i2c-core | ||
210 | and other utilities: | ||
211 | |||
212 | + struct i2c_device_id example_idtable[] = { | ||
213 | + { "example", 0 }, | ||
214 | + { } | ||
215 | +}; | ||
216 | + | ||
217 | +MODULE_DEVICE_TABLE(i2c, example_idtable); | ||
218 | |||
219 | static struct i2c_driver example_driver = { | ||
220 | .driver = { | ||
221 | .owner = THIS_MODULE, | ||
222 | .name = "example", | ||
223 | }, | ||
224 | + .id_table = example_ids, | ||
225 | |||
226 | |||
227 | Our driver should now look like this: | ||
228 | |||
229 | struct example_state { | ||
230 | struct i2c_client *client; | ||
231 | .... | ||
232 | }; | ||
233 | |||
234 | static int example_probe(struct i2c_client *client, | ||
235 | const struct i2c_device_id *id) | ||
236 | { | ||
237 | struct example_state *state; | ||
238 | struct device *dev = &client->dev; | ||
239 | |||
240 | state = kzalloc(sizeof(struct example_state), GFP_KERNEL); | ||
241 | if (state == NULL) { | ||
242 | dev_err(dev, "failed to create our state\n"); | ||
243 | return -ENOMEM; | ||
244 | } | ||
245 | |||
246 | state->client = client; | ||
247 | i2c_set_clientdata(client, state); | ||
248 | |||
249 | /* rest of the initialisation goes here. */ | ||
250 | |||
251 | dev_info(dev, "example client created\n"); | ||
252 | |||
253 | return 0; | ||
254 | } | ||
255 | |||
256 | static int __devexit example_remove(struct i2c_client *client) | ||
257 | { | ||
258 | struct example_state *state = i2c_get_clientdata(client); | ||
259 | |||
260 | kfree(state); | ||
261 | return 0; | ||
262 | } | ||
263 | |||
264 | static struct i2c_device_id example_idtable[] = { | ||
265 | { "example", 0 }, | ||
266 | { } | ||
267 | }; | ||
268 | |||
269 | MODULE_DEVICE_TABLE(i2c, example_idtable); | ||
270 | |||
271 | static struct i2c_driver example_driver = { | ||
272 | .driver = { | ||
273 | .owner = THIS_MODULE, | ||
274 | .name = "example", | ||
275 | }, | ||
276 | .id_table = example_idtable, | ||
277 | .probe = example_probe, | ||
278 | .remove = __devexit_p(example_remove), | ||
279 | .suspend = example_suspend, | ||
280 | .resume = example_resume, | ||
281 | }; | ||