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SPI can only use 5 address bits, since one bit is reserved for specifying R/W and 2 bits are used to specify the UART port. To access registers that have addresses past 0x1F, an extended register space can be enabled by writing to the GlobalCommand register (address 0x1F). I2C uses 8 address bits. The R/W bit is placed in the slave address, and so is the UART port. Because of this, registers that have addresses higher than 0x1F can be accessed normally. To access the RevID register, on SPI, 0xCE must be written to the 0x1F address to enable the extended register space, after which the RevID register is accessible at address 0x5. 0xCD must be written to the 0x1F address to disable the extended register space. On I2C, the RevID register is accessible at address 0x25. Create an interface config struct, and add a method for toggling the extended register space and a member for the RevId register address. Implement these for SPI. Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: Cosmin Tanislav <cosmin.tanislav@analog.com> Link: https://lore.kernel.org/r/20220605144659.4169853-4-demonsingur@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.