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    SubjectRe: [PATCH 01/10] regmap-irq: Add get_irq_reg to support unusual register layouts
    On Fri, Jun 03, 2022 at 02:57:05PM +0100, Aidan MacDonald wrote:
    > Add a new callback, get_irq_reg, for regmap IRQ chips, to support devices
    > with unusual register layouts. This is required in the rare cases where
    > the offset of an IRQ register is not constant with respect to the base
    > register. This is probably best illustrated with an example:
    >
    > mask status
    > IRQ0 0x40 0x44
    > IRQ1 0x41 0x45
    > IRQ2 0x42 0x46
    > IRQ3 0x43 0x47
    > IRQ4 0x4a 0x4d
    >
    > If we set mask_base = 0x40 and status_base = 0x44, the offsets of each
    > register relative to the base are:
    >
    > mask status
    > IRQ0 0 0
    > IRQ1 1 1
    > IRQ2 2 2
    > IRQ3 3 3
    > IRQ4 10 9
    >
    > The existing mapping mechanisms can't include IRQ4 in the same irqchip
    > as IRQ0-3 because the offset of IRQ4's register depends on which type
    > of register we're asking for, ie. which base register is used.
    >
    > The get_irq_reg callback allows drivers to specify an arbitrary mapping
    > of (base register, register index) pairs to register addresses, instead
    > of the default linear mapping "base_register + register_index". This
    > allows unusual layouts, like the one above, to be handled using a single
    > regmap IRQ chip.
    >
    > The drawback is that when get_irq_reg is used, it's impossible to use
    > bulk reads for status registers even if some of them are contiguous,
    > because the mapping is opaque to regmap-irq. This should be acceptable
    > for the case of a few infrequently-polled status registers.

    This patch does two things:

    1. Add a new callback `get_irq_reg`
    2. Replace unmask_offset calculation with call to sub_irq_reg()

    Could you please split the patch into two to better reflect this?

    Thank you.

    Guru Das.

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