Messages in this thread Patch in this message |  | | From | Andrea Tomassetti <> | | Subject | [PATCH v2] mux: gpio-mux: add support for 4:1 2-channels mux | | Date | Wed, 6 May 2026 14:33:50 +0200 |
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Some gpio multiplexers, like TMUX1209, offer differential 4:1 or dual 4:1 single-ended channels. No binding changes are needed because the DT binding already supports #mux-control-cells with values 0 and 1. So, similarly to what was already done by the adg792a driver, the gpio-mux driver has to take into account the #mux-control-cells property and allocate as many controllers as advised by it.
As an example, in the DTS you can now define:
tmux1209: mux-controller { compatible = "gpio-mux"; #mux-control-cells = <1>;
mux-gpios = <&gpio_expander 01 GPIO_ACTIVE_HIGH>, <&gpio_expander 02 GPIO_ACTIVE_HIGH>; };
And use it like this:
adcmux30: adcmux30 { compatible = "io-channel-mux"; io-channels = <&adc1 4>; io-channel-names = "parent"; #io-channel-cells = <1>; mux-controls = <&tmux1209 0>;
channels = "S1A", "S2A", "S3A", "S4A"; };
adcmux31: adcmux31 { compatible = "io-channel-mux"; io-channels = <&adc1 5>; io-channel-names = "parent"; #io-channel-cells = <1>; mux-controls = <&tmux1209 1>;
channels = "S1B", "S2B", "S3B", "S4B"; };
Signed-off-by: Andrea Tomassetti <andrea.tomassetti@sipearl.com> Reviewed-by: Linus Walleij <linusw@kernel.org> --- v2: Address feedback from Linus Walleij - reword commit message by making clear that patching the binding is not needed - make clear from error message that binding only allows 0 or 1 - fix two other locations where `mux` was accessed
drivers/mux/gpio.c | 24 +++++++++++++++++++----- 1 file changed, 19 insertions(+), 5 deletions(-)
diff --git a/drivers/mux/gpio.c b/drivers/mux/gpio.c index 4cc3202c58f3..ab3ed5247d2c 100644 --- a/drivers/mux/gpio.c +++ b/drivers/mux/gpio.c @@ -52,12 +52,23 @@ static int mux_gpio_probe(struct platform_device *pdev) int pins; s32 idle_state; int ret; + u32 cells; + int i;
pins = gpiod_count(dev, "mux"); if (pins < 0) return pins;
- mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*mux_gpio)); + ret = device_property_read_u32(dev, "#mux-control-cells", &cells); + if (ret < 0) + cells = 0; + + if (cells >= 2) { + dev_err(dev, "invalid control-cells %u, must be 0 or 1\n", cells); + return -EINVAL; + } + + mux_chip = devm_mux_chip_alloc(dev, cells + 1, sizeof(*mux_gpio)); if (IS_ERR(mux_chip)) return PTR_ERR(mux_chip);
@@ -69,7 +80,9 @@ static int mux_gpio_probe(struct platform_device *pdev) return dev_err_probe(dev, PTR_ERR(mux_gpio->gpios), "failed to get gpios\n"); WARN_ON(pins != mux_gpio->gpios->ndescs); - mux_chip->mux->states = BIT(pins); + + for (i = 0; i < mux_chip->controllers; ++i) + mux_chip->mux[i].states = BIT(pins);
ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state); if (ret >= 0 && idle_state != MUX_IDLE_AS_IS) { @@ -78,7 +91,8 @@ static int mux_gpio_probe(struct platform_device *pdev) return -EINVAL; }
- mux_chip->mux->idle_state = idle_state; + for (i = 0; i < mux_chip->controllers; ++i) + mux_chip->mux[i].idle_state = idle_state; }
ret = devm_regulator_get_enable_optional(dev, "mux"); @@ -89,8 +103,8 @@ static int mux_gpio_probe(struct platform_device *pdev) if (ret < 0) return ret;
- dev_info(dev, "%u-way mux-controller registered\n", - mux_chip->mux->states); + dev_info(dev, "%u-way mux-controller registered, %u controllers\n", + mux_chip->mux->states, mux_chip->controllers);
return 0; } base-commit: 74fe02ce122a6103f207d29fafc8b3a53de6abaf -- 2.51.2
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