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author | David S. Miller <davem@davemloft.net> | 2008-07-18 13:39:39 +0400 |
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committer | David S. Miller <davem@davemloft.net> | 2008-07-18 13:39:39 +0400 |
commit | 49997d75152b3d23c53b0fa730599f2f74c92c65 (patch) | |
tree | 46e93126170d02cfec9505172e545732c1b69656 /Documentation/i2c/writing-clients | |
parent | a0c80b80e0fb48129e4e9d6a9ede914f9ff1850d (diff) | |
parent | 5b664cb235e97afbf34db9c4d77f08ebd725335e (diff) | |
download | linux-49997d75152b3d23c53b0fa730599f2f74c92c65.tar.xz |
Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/torvalds/linux-2.6
Conflicts:
Documentation/powerpc/booting-without-of.txt
drivers/atm/Makefile
drivers/net/fs_enet/fs_enet-main.c
drivers/pci/pci-acpi.c
net/8021q/vlan.c
net/iucv/iucv.c
Diffstat (limited to 'Documentation/i2c/writing-clients')
-rw-r--r-- | Documentation/i2c/writing-clients | 51 |
1 files changed, 40 insertions, 11 deletions
diff --git a/Documentation/i2c/writing-clients b/Documentation/i2c/writing-clients index d4cd4126d1ad..6b61b3a2e90b 100644 --- a/Documentation/i2c/writing-clients +++ b/Documentation/i2c/writing-clients @@ -44,6 +44,10 @@ static struct i2c_driver foo_driver = { .id_table = foo_ids, .probe = foo_probe, .remove = foo_remove, + /* if device autodetection is needed: */ + .class = I2C_CLASS_SOMETHING, + .detect = foo_detect, + .address_data = &addr_data, /* else, driver uses "legacy" binding model: */ .attach_adapter = foo_attach_adapter, @@ -217,6 +221,31 @@ in the I2C bus driver. You may want to save the returned i2c_client reference for later use. +Device Detection (Standard driver model) +---------------------------------------- + +Sometimes you do not know in advance which I2C devices are connected to +a given I2C bus. This is for example the case of hardware monitoring +devices on a PC's SMBus. In that case, you may want to let your driver +detect supported devices automatically. This is how the legacy model +was working, and is now available as an extension to the standard +driver model (so that we can finally get rid of the legacy model.) + +You simply have to define a detect callback which will attempt to +identify supported devices (returning 0 for supported ones and -ENODEV +for unsupported ones), a list of addresses to probe, and a device type +(or class) so that only I2C buses which may have that type of device +connected (and not otherwise enumerated) will be probed. The i2c +core will then call you back as needed and will instantiate a device +for you for every successful detection. + +Note that this mechanism is purely optional and not suitable for all +devices. You need some reliable way to identify the supported devices +(typically using device-specific, dedicated identification registers), +otherwise misdetections are likely to occur and things can get wrong +quickly. + + Device Deletion (Standard driver model) --------------------------------------- @@ -569,7 +598,6 @@ SMBus communication in terms of it. Never use this function directly! - extern s32 i2c_smbus_write_quick(struct i2c_client * client, u8 value); extern s32 i2c_smbus_read_byte(struct i2c_client * client); extern s32 i2c_smbus_write_byte(struct i2c_client * client, u8 value); extern s32 i2c_smbus_read_byte_data(struct i2c_client * client, u8 command); @@ -578,30 +606,31 @@ SMBus communication extern s32 i2c_smbus_read_word_data(struct i2c_client * client, u8 command); extern s32 i2c_smbus_write_word_data(struct i2c_client * client, u8 command, u16 value); + extern s32 i2c_smbus_read_block_data(struct i2c_client * client, + u8 command, u8 *values); extern s32 i2c_smbus_write_block_data(struct i2c_client * client, u8 command, u8 length, u8 *values); extern s32 i2c_smbus_read_i2c_block_data(struct i2c_client * client, u8 command, u8 length, u8 *values); - -These ones were removed in Linux 2.6.10 because they had no users, but could -be added back later if needed: - - extern s32 i2c_smbus_read_block_data(struct i2c_client * client, - u8 command, u8 *values); extern s32 i2c_smbus_write_i2c_block_data(struct i2c_client * client, u8 command, u8 length, u8 *values); + +These ones were removed from i2c-core because they had no users, but could +be added back later if needed: + + extern s32 i2c_smbus_write_quick(struct i2c_client * client, u8 value); extern s32 i2c_smbus_process_call(struct i2c_client * client, u8 command, u16 value); extern s32 i2c_smbus_block_process_call(struct i2c_client *client, u8 command, u8 length, u8 *values) -All these transactions return -1 on failure. The 'write' transactions -return 0 on success; the 'read' transactions return the read value, except -for read_block, which returns the number of values read. The block buffers -need not be longer than 32 bytes. +All these transactions return a negative errno value on failure. The 'write' +transactions return 0 on success; the 'read' transactions return the read +value, except for block transactions, which return the number of values +read. The block buffers need not be longer than 32 bytes. You can read the file `smbus-protocol' for more information about the actual SMBus protocol. |