pinctrl: aspeed: Fix GPIO requests on pass-through banks (7aeb3538) · Commits · 戴 / test

drivers/pinctrl/aspeed/pinctrl-aspeed.c

+68 −6

Original line number	Diff line number	Diff line
		@@ -286,14 +286,76 @@ int aspeed_pinmux_set_mux(struct pinctrl_dev *pctldev, unsigned int function,
		static bool aspeed_expr_is_gpio(const struct aspeed_sig_expr *expr)
		{
		/*
		* The signal type is GPIO if the signal name has "GPI" as a prefix.
		* strncmp (rather than strcmp) is used to implement the prefix
		* requirement.
		* We need to differentiate between GPIO and non-GPIO signals to
		* implement the gpio_request_enable() interface. For better or worse
		* the ASPEED pinctrl driver uses the expression names to determine
		* whether an expression will mux a pin for GPIO.
		*
		* expr->signal might look like "GPIOB1" in the GPIO case.
		* expr->signal might look like "GPIT0" in the GPI case.
		* Generally we have the following - A GPIO such as B1 has:
		*
		* - expr->signal set to "GPIOB1"
		* - expr->function set to "GPIOB1"
		*
		* Using this fact we can determine whether the provided expression is
		* a GPIO expression by testing the signal name for the string prefix
		* "GPIO".
		*
		* However, some GPIOs are input-only, and the ASPEED datasheets name
		* them differently. An input-only GPIO such as T0 has:
		*
		* - expr->signal set to "GPIT0"
		* - expr->function set to "GPIT0"
		*
		* It's tempting to generalise the prefix test from "GPIO" to "GPI" to
		* account for both GPIOs and GPIs, but in doing so we run aground on
		* another feature:
		*
		* Some pins in the ASPEED BMC SoCs have a "pass-through" GPIO
		* function where the input state of one pin is replicated as the
		* output state of another (as if they were shorted together - a mux
		* configuration that is typically enabled by hardware strapping).
		* This feature allows the BMC to pass e.g. power button state through
		* to the host while the BMC is yet to boot, but take control of the
		* button state once the BMC has booted by muxing each pin as a
		* separate, pin-specific GPIO.
		*
		* Conceptually this pass-through mode is a form of GPIO and is named
		* as such in the datasheets, e.g. "GPID0". This naming similarity
		* trips us up with the simple GPI-prefixed-signal-name scheme
		* discussed above, as the pass-through configuration is not what we
		* want when muxing a pin as GPIO for the GPIO subsystem.
		*
		* On e.g. the AST2400, a pass-through function "GPID0" is grouped on
		* balls A18 and D16, where we have:
		*
		* For ball A18:
		* - expr->signal set to "GPID0IN"
		* - expr->function set to "GPID0"
		*
		* For ball D16:
		* - expr->signal set to "GPID0OUT"
		* - expr->function set to "GPID0"
		*
		* By contrast, the pin-specific GPIO expressions for the same pins are
		* as follows:
		*
		* For ball A18:
		* - expr->signal looks like "GPIOD0"
		* - expr->function looks like "GPIOD0"
		*
		* For ball D16:
		* - expr->signal looks like "GPIOD1"
		* - expr->function looks like "GPIOD1"
		*
		* Testing both the signal _and_ function names gives us the means
		* differentiate the pass-through GPIO pinmux configuration from the
		* pin-specific configuration that the GPIO subsystem is after: An
		* expression is a pin-specific (non-pass-through) GPIO configuration
		* if the signal prefix is "GPI" and the signal name matches the
		* function name.
		*/
		return strncmp(expr->signal, "GPI", 3) == 0;
		return !strncmp(expr->signal, "GPI", 3) &&
		!strcmp(expr->signal, expr->function);
		}

		static bool aspeed_gpio_in_exprs(const struct aspeed_sig_expr **exprs)

drivers/pinctrl/aspeed/pinmux-aspeed.h

+4 −3

Original line number	Diff line number	Diff line
		@@ -452,10 +452,11 @@ struct aspeed_sig_desc {
		* evaluation of the descriptors.
		*
		* @signal: The signal name for the priority level on the pin. If the signal
		* type is GPIO, then the signal name must begin with the string
		* "GPIO", e.g. GPIOA0, GPIOT4 etc.
		* type is GPIO, then the signal name must begin with the
		* prefix "GPI", e.g. GPIOA0, GPIT0 etc.
		* @function: The name of the function the signal participates in for the
		* associated expression
		* associated expression. For pin-specific GPIO, the function
		* name must match the signal name.
		* @ndescs: The number of signal descriptors in the expression
		* @descs: Pointer to an array of signal descriptors that comprise the
		* function expression

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