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If it is necessary to re-initialize the chip, for example because it has been power cycled, use regmap functions to update register contents. This ensures that all registers, including the configuration register and alert registers, are updated to previously configured values without having to locally cache everything. For this to work, volatile registers have to be marked as volatile. Also, the cache needs to be bypassed when reading the calibration and mask_enable registers. While the calibration register is not volatile, it will be reset to 0 if the chip has been power cycled. Most of the bits in the mask_enable register are configuration bits, except for bit 4 which reports if an alert has been observed. Both registers need to be marked as non-volatile to be updated after a power cycle, but it is necessary to bypass the cache when reading them to detect if the chip has been power cycled and to read the alert status. The chip does not support register auto-increments. It is therefore necessary to configure regmap to use single register read/write operations. Otherwise regmap tries to write all registers in a single operation when synchronizing register contents with the hardware, and the synchronization fails. Another necessary change is to declare ina226_alert_to_reg() as u16. So far it returned an s16 which is sign extended to a large negative value which is then sent to regmap as unsigned int, causing an -EINVAL error return. Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
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 reStructuredText 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.