diff options
| author | Wolfram Sang <wsa+renesas@sang-engineering.com> | 2015-07-27 08:03:38 -0400 |
|---|---|---|
| committer | Wolfram Sang <wsa@the-dreams.de> | 2015-08-24 08:05:15 -0400 |
| commit | cfa0327b0d03091e0c47249c080e50e287be762d (patch) | |
| tree | 623f03aee6dc0bbdaada27b4f2cab5e4a7fd87fd /Documentation/i2c | |
| parent | 9bccc70a127cfe2a13e34d6b6e7300caae113f8f (diff) | |
i2c: support 10 bit and slave addresses in sysfs 'new_device'
We now have seperate address spaces for 10 bit and we-are-slave clients.
Update the sysfs device instantiation method to support these types by
accepting the address offsets that are assigned to the extra address
spaces. Update the documentation, too.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'Documentation/i2c')
| -rw-r--r-- | Documentation/i2c/slave-interface | 9 | ||||
| -rw-r--r-- | Documentation/i2c/ten-bit-addresses | 4 |
2 files changed, 10 insertions, 3 deletions
diff --git a/Documentation/i2c/slave-interface b/Documentation/i2c/slave-interface index 2dee4e2d62df..61ed05cd9531 100644 --- a/Documentation/i2c/slave-interface +++ b/Documentation/i2c/slave-interface | |||
| @@ -31,10 +31,13 @@ User manual | |||
| 31 | =========== | 31 | =========== |
| 32 | 32 | ||
| 33 | I2C slave backends behave like standard I2C clients. So, you can instantiate | 33 | I2C slave backends behave like standard I2C clients. So, you can instantiate |
| 34 | them as described in the document 'instantiating-devices'. A quick example for | 34 | them as described in the document 'instantiating-devices'. The only difference |
| 35 | instantiating the slave-eeprom driver from userspace at address 0x64 on bus 1: | 35 | is that i2c slave backends have their own address space. So, you have to add |
| 36 | 0x1000 to the address you would originally request. An example for | ||
| 37 | instantiating the slave-eeprom driver from userspace at the 7 bit address 0x64 | ||
| 38 | on bus 1: | ||
| 36 | 39 | ||
| 37 | # echo slave-24c02 0x64 > /sys/bus/i2c/devices/i2c-1/new_device | 40 | # echo slave-24c02 0x1064 > /sys/bus/i2c/devices/i2c-1/new_device |
| 38 | 41 | ||
| 39 | Each backend should come with separate documentation to describe its specific | 42 | Each backend should come with separate documentation to describe its specific |
| 40 | behaviour and setup. | 43 | behaviour and setup. |
diff --git a/Documentation/i2c/ten-bit-addresses b/Documentation/i2c/ten-bit-addresses index cdfe13901b99..7b2d11e53a49 100644 --- a/Documentation/i2c/ten-bit-addresses +++ b/Documentation/i2c/ten-bit-addresses | |||
| @@ -2,6 +2,10 @@ The I2C protocol knows about two kinds of device addresses: normal 7 bit | |||
| 2 | addresses, and an extended set of 10 bit addresses. The sets of addresses | 2 | addresses, and an extended set of 10 bit addresses. The sets of addresses |
| 3 | do not intersect: the 7 bit address 0x10 is not the same as the 10 bit | 3 | do not intersect: the 7 bit address 0x10 is not the same as the 10 bit |
| 4 | address 0x10 (though a single device could respond to both of them). | 4 | address 0x10 (though a single device could respond to both of them). |
| 5 | To avoid ambiguity, the user sees 10 bit addresses mapped to a different | ||
| 6 | address space, namely 0xa000-0xa3ff. The leading 0xa (= 10) represents the | ||
| 7 | 10 bit mode. This is used for creating device names in sysfs. It is also | ||
| 8 | needed when instantiating 10 bit devices via the new_device file in sysfs. | ||
| 5 | 9 | ||
| 6 | I2C messages to and from 10-bit address devices have a different format. | 10 | I2C messages to and from 10-bit address devices have a different format. |
| 7 | See the I2C specification for the details. | 11 | See the I2C specification for the details. |