regmap-irq: Update interrupt clear register for proper reset

regmap-irq: Update interrupt clear register for proper reset

With the existing logic where clear_ack is true (HW doesn’t support
auto clear for ICR), interrupt clear register reset is not handled
properly. Due to this only the first interrupts get processed properly
and further interrupts are blocked due to not resetting interrupt
clear register.

Example for issue case where Invert_ack is false and clear_ack is true:

    Say Default ISR=0x00 & ICR=0x00 and ISR is triggered with 2
    interrupts making ISR = 0x11.

    Step 1: Say ISR is set 0x11 (store status_buff = ISR). ISR needs to
            be cleared with the help of ICR once the Interrupt is processed.

    Step 2: Write ICR = 0x11 (status_buff), this will clear the ISR to 0x00.

    Step 3: Issue - In the existing code, ICR is written with ICR =
            ~(status_buff) i.e ICR = 0xEE -> This will block all the interrupts
            from raising except for interrupts 0 and 4. So expectation here is to
            reset ICR, which will unblock all the interrupts.

            if (chip->clear_ack) {
                 if (chip->ack_invert && !ret)
                  ........
                 else if (!ret)
                     ret = regmap_write(map, reg,
                            ~data->status_buf[i]);

So writing 0 and 0xff (when ack_invert is true) should have no effect, other
than clearing the ACKs just set.

Fixes: 3a6f0fb7b8eb ("regmap: irq: Add support to clear ack registers")
Signed-off-by: Prasad Kumpatla <quic_pkumpatl@quicinc.com>
Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20220217085007.30218-1-quic_pkumpatl@quicinc.com
Signed-off-by: Mark Brown <broonie@kernel.org>