[PATCH 0/3] i2c: mux: gpio: Add 'transition-delay-ms' property

Bastien Curutchet
2024-05-27T11:39:19Z

Hi all,

The i2c-gpio-mux can be used to describe a multiplexer built upon
several i2c isolators having an enable pin (such as LTC4310):

+---------------+ +------+ +------+
| +-----------+ | | dev | | dev |
| | GPIO_EN_A |-|-----------| +------+ +------+
| +-----------+ | +-----+---+ | |
| | |--| isol. A |---------+---------+
| +-----+ | | +---------+
| SOC | I2C |---|--|
| +-----+ | | +---------+
| | |--| isol. B |------+---------+---------+
| +-----------+ | +-----+---+ | | |
| | GPIO_EN_B |-|-----------| +------+ +------+ +------+
| +-----------+ | | dev | | dev | | dev |
+---------------+ +------+ +------+ +------+

These isolators often need some time between their enable pin's
assertion and the first i2c transfer. If the first i2c transfer
happens before this enabling time is reached, transfer fails.

There is no available option to configure such a time in the
i2c-gpio-mux driver.

Add a optional property in the bindings called 'transition-delay-ms'.
If present, driver waits for this delay every time a new bus is
selected, i.e. before returning from the bus_select() callback.

Bastien Curutchet (3):
dt-bindings: i2c: gpio: Add 'transition-delay-ms' property
i2c: mux: gpio: Re-order #include to match alphabetic order
i2c: mux: gpio: Add support for the 'transition-delay-ms' property

.../devicetree/bindings/i2c/i2c-mux-gpio.yaml | 3 +++
drivers/i2c/muxes/i2c-mux-gpio.c | 14 ++++++++++----
include/linux/platform_data/i2c-mux-gpio.h | 2 ++
3 files changed, 15 insertions(+), 4 deletions(-)

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2.44.0