mfd: max77620: Fix potential IRQ chip conflict when probing two devices

mfd: max77620: Fix potential IRQ chip conflict when probing two devices

commit 2bac49bad1f3553cc3b3bfb22cc194e9bd9e8427 upstream.

MAX77620 is most likely always a single device on the board, however
nothing stops board designers to have two of them, thus same device
driver could probe twice. Or user could manually try to probing second
time.

Device driver is not ready for that case, because it allocates
statically 'struct regmap_irq_chip' as non-const and stores during
probe in 'irq_drv_data' member a pointer to per-probe state
container ('struct max77620_chip').  devm_regmap_add_irq_chip() does not
make a copy of 'struct regmap_irq_chip' but store the pointer.

Second probe - either successful or failure - would overwrite the
'irq_drv_data' from previous device probe, so interrupts would be
executed in a wrong context.

Cc: stable@vger.kernel.org
Fixes: 3df140d11c6d ("mfd: max77620: Mask/unmask interrupt before/after servicing it")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://patch.msgid.link/20251023101939.67991-2-krzysztof.kozlowski@linaro.org
Signed-off-by: Lee Jones <lee@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>