Merge tag 'pinctrl-v5.10-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl

Pull pin control fixes from Linus Walleij:
 "Here is a late set of pin control fixes for v5.10, most concern some
  minor and major issues found in the Intel drivers. Some are so hairy
  that I have no idea what is going on there, but luckily the maintainer
  knows what's up.

  We also have an interesting fix for AMD, which makes AMD-based laptops
  more stable IIUC.

  Summary:

   - Fix up some SPI group and a register offset on Intel Jasperlake

   - Set default bias on Intel Merrifield

   - Preserve debouncing on Intel Baytrail

   - Stop .set_type() irqchip callback in the AMD driver from fiddling
     with the debounce filter

   - Fix access to GPIO banks that are pass-thru on the Aspeed

   - Fix a fix for the Intel pin control driver to disable Rx/Tx when
     requesting a UART line as GPIO"

* tag 'pinctrl-v5.10-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl: intel: Actually disable Tx and Rx buffers on GPIO request
  pinctrl: aspeed: Fix GPIO requests on pass-through banks
  pinctrl: amd: remove debounce filter setting in IRQ type setting
  pinctrl: baytrail: Avoid clearing debounce value when turning it off
  pinctrl: merrifield: Set default bias in case no particular value given
  pinctrl: jasperlake: Fix HOSTSW_OWN offset
  pinctrl: jasperlake: Unhide SPI group of pins

Author: torvalds

drivers/pinctrl/aspeed/pinctrl-aspeed.c

@@ -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

@@ -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

drivers/pinctrl/intel/pinctrl-baytrail.c

@@ -1049,7 +1049,6 @@ static int byt_pin_config_set(struct pinctrl_dev *pctl_dev,
 			break;
 		case PIN_CONFIG_INPUT_DEBOUNCE:
 			debounce = readl(db_reg);
-			debounce &= ~BYT_DEBOUNCE_PULSE_MASK;
 
 			if (arg)
 				conf |= BYT_DEBOUNCE_EN;
@@ -1058,24 +1057,31 @@ static int byt_pin_config_set(struct pinctrl_dev *pctl_dev,
 
 			switch (arg) {
 			case 375:
+				debounce &= ~BYT_DEBOUNCE_PULSE_MASK;
 				debounce |= BYT_DEBOUNCE_PULSE_375US;
 				break;
 			case 750:
+				debounce &= ~BYT_DEBOUNCE_PULSE_MASK;
 				debounce |= BYT_DEBOUNCE_PULSE_750US;
 				break;
 			case 1500:
+				debounce &= ~BYT_DEBOUNCE_PULSE_MASK;
 				debounce |= BYT_DEBOUNCE_PULSE_1500US;
 				break;
 			case 3000:
+				debounce &= ~BYT_DEBOUNCE_PULSE_MASK;
 				debounce |= BYT_DEBOUNCE_PULSE_3MS;
 				break;
 			case 6000:
+				debounce &= ~BYT_DEBOUNCE_PULSE_MASK;
 				debounce |= BYT_DEBOUNCE_PULSE_6MS;
 				break;
 			case 12000:
+				debounce &= ~BYT_DEBOUNCE_PULSE_MASK;
 				debounce |= BYT_DEBOUNCE_PULSE_12MS;
 				break;
 			case 24000:
+				debounce &= ~BYT_DEBOUNCE_PULSE_MASK;
 				debounce |= BYT_DEBOUNCE_PULSE_24MS;
 				break;
 			default:

drivers/pinctrl/intel/pinctrl-intel.c

@@ -442,8 +442,8 @@ static void intel_gpio_set_gpio_mode(void __iomem *padcfg0)
 	value |= PADCFG0_PMODE_GPIO;
 
 	/* Disable input and output buffers */
-	value &= ~PADCFG0_GPIORXDIS;
-	value &= ~PADCFG0_GPIOTXDIS;
+	value |= PADCFG0_GPIORXDIS;
+	value |= PADCFG0_GPIOTXDIS;
 
 	/* Disable SCI/SMI/NMI generation */
 	value &= ~(PADCFG0_GPIROUTIOXAPIC | PADCFG0_GPIROUTSCI);