Add a strict_gpiod option

arch/arm/boot/dts/broadcom/bcm270x-rpi.dtsi

@@ -110,6 +110,8 @@
 		cam0_sync_inverted = <&csi0>, "sync-gpios:0=", <&gpio>,
 			    <&csi0>, "sync-gpios:4",
 			    <&csi0>, "sync-gpios:8=0", <GPIO_ACTIVE_LOW>;
+
+		strict_gpiod = <&chosen>, "bootargs=pinctrl_bcm2835.strict_gpiod=y";
 	};
 };
 

arch/arm/boot/dts/broadcom/bcm2712-rpi.dtsi

@@ -99,6 +99,7 @@
 		nvmem_cust_rw = <&nvmem_cust>,"rw?";
 		nvmem_priv_rw = <&nvmem_priv>,"rw?";
 		nvmem_mac_rw = <&nvmem_mac>,"rw?";
+		strict_gpiod = <&chosen>, "bootargs=pinctrl_rp1.strict_gpiod=y";
 	};
 };
 

arch/arm/boot/dts/broadcom/rp1.dtsi

@@ -465,6 +465,7 @@
 			#gpio-cells = <2>;
 			interrupt-controller;
 			#interrupt-cells = <2>;
+			gpio-ranges = <&rp1_gpio 0 0 54>;
 
 			rp1_uart0_14_15: rp1_uart0_14_15 {
 				pin_txd {

arch/arm/boot/dts/overlays/README

@@ -130,6 +130,23 @@ Name:   <The base DTB>
 Info:   Configures the base Raspberry Pi hardware
 Load:   <loaded automatically>
 Params:
+        act_led_trigger         Choose which activity the LED tracks.
+                                Use "heartbeat" for a nice load indicator.
+                                (default "mmc")
+
+        act_led_activelow       Set to "on" to invert the sense of the LED
+                                (default "off")
+                                N.B. For Pi 3B, 3B+, 3A+ and 4B, use the act-led
+                                overlay.
+
+        act_led_gpio            Set which GPIO to use for the activity LED
+                                (in case you want to connect it to an external
+                                device)
+                                (default "16" on a non-Plus board, "47" on a
+                                Plus or Pi 2)
+                                N.B. For Pi 3B, 3B+, 3A+ and 4B, use the act-led
+                                overlay.
+
         ant1                    Select antenna 1 (default). CM4/5 only.
 
         ant2                    Select antenna 2. CM4/5 only.
@@ -340,12 +357,11 @@ Params:
         pciex1_tperst_clk_ms    Alias for pcie_tperst_clk_ms
                                 (2712 only, default "0")
 
-        spi                     Set to "on" to enable the spi interfaces
-                                (default "off")
-
-        spi_dma4                Use to enable 40-bit DMA on spi interfaces
-                                (the assigned value doesn't matter)
-                                (2711 only)
+        pwr_led_trigger
+        pwr_led_activelow
+        pwr_led_gpio
+                                As for act_led_*, but using the PWR LED.
+                                Not available on Model A/B boards.
 
         random                  Set to "on" to enable the hardware random
                                 number generator (default "on")
@@ -386,6 +402,19 @@ Params:
         sdio_overclock          Clock (in MHz) to use when the MMC framework
                                 requests 50MHz for the SDIO/WLAN interface.
 
+        spi                     Set to "on" to enable the spi interfaces
+                                (default "off")
+
+        spi_dma4                Use to enable 40-bit DMA on spi interfaces
+                                (the assigned value doesn't matter)
+                                (2711 only)
+
+        strict_gpiod            Return GPIOs to inputs when they are released.
+                                If using the gpiod utilities, it is necessary
+                                to keep a gpioset running (e.g. with
+                                --mode=wait) in order for an output value to
+                                persist.
+
         suspend                 Make the power button trigger a suspend rather
                                 than a power-off (2712 only, default "off")
 
@@ -410,29 +439,6 @@ Params:
                                 with or without colon separators, written in the
                                 natural (big-endian) order.
 
-        act_led_trigger         Choose which activity the LED tracks.
-                                Use "heartbeat" for a nice load indicator.
-                                (default "mmc")
-
-        act_led_activelow       Set to "on" to invert the sense of the LED
-                                (default "off")
-                                N.B. For Pi 3B, 3B+, 3A+ and 4B, use the act-led
-                                overlay.
-
-        act_led_gpio            Set which GPIO to use for the activity LED
-                                (in case you want to connect it to an external
-                                device)
-                                (default "16" on a non-Plus board, "47" on a
-                                Plus or Pi 2)
-                                N.B. For Pi 3B, 3B+, 3A+ and 4B, use the act-led
-                                overlay.
-
-        pwr_led_trigger
-        pwr_led_activelow
-        pwr_led_gpio
-                                As for act_led_*, but using the PWR LED.
-                                Not available on Model A/B boards.
-
         N.B. It is recommended to only enable those interfaces that are needed.
         Leaving all interfaces enabled can lead to unwanted behaviour (i2c_vc
         interfering with Pi Camera, I2S and SPI hogging GPIO pins, etc.)

drivers/pinctrl/bcm/pinctrl-bcm2835.c

@@ -244,6 +244,10 @@ static const char * const irq_type_names[] = {
 	[IRQ_TYPE_LEVEL_LOW] = "level-low",
 };
 
+static bool strict_gpiod;
+module_param(strict_gpiod, bool, 0644);
+MODULE_PARM_DESC(strict_gpiod, "unless true, outputs remain outputs when freed");
+
 static inline u32 bcm2835_gpio_rd(struct bcm2835_pinctrl *pc, unsigned reg)
 {
 	return readl(pc->base + reg);
@@ -941,8 +945,8 @@ static int bcm2835_pmx_free(struct pinctrl_dev *pctldev,
 	struct bcm2835_pinctrl *pc = pinctrl_dev_get_drvdata(pctldev);
 	enum bcm2835_fsel fsel = bcm2835_pinctrl_fsel_get(pc, offset);
 
-	/* Return non-GPIOs to GPIO_IN */
-	if (fsel != BCM2835_FSEL_GPIO_IN && fsel != BCM2835_FSEL_GPIO_OUT)
+	/* Return non-GPIOs to GPIO_IN, unless strict_gpiod is set */
+	if (strict_gpiod || (fsel != BCM2835_FSEL_GPIO_IN && fsel != BCM2835_FSEL_GPIO_OUT))
 		bcm2835_pinctrl_fsel_set(pc, offset, BCM2835_FSEL_GPIO_IN);
 
 	return 0;

drivers/pinctrl/pinctrl-rp1.c

@@ -573,6 +573,10 @@ static const char * const irq_type_names[] = {
 	[IRQ_TYPE_LEVEL_LOW] = "level-low",
 };
 
+static bool strict_gpiod;
+module_param(strict_gpiod, bool, 0644);
+MODULE_PARM_DESC(strict_gpiod, "unless true, outputs remain outputs when freed");
+
 static int rp1_pinconf_set(struct pinctrl_dev *pctldev,
 			   unsigned int offset, unsigned long *configs,
 			   unsigned int num_configs);
@@ -1201,8 +1205,8 @@ static int rp1_pmx_free(struct pinctrl_dev *pctldev, unsigned offset)
 	struct rp1_pin_info *pin = rp1_get_pin_pctl(pctldev, offset);
 	u32 fsel = rp1_get_fsel(pin);
 
-	/* Return non-GPIOs to GPIO_IN */
-	if (fsel != RP1_FSEL_GPIO) {
+	/* Return non-GPIOs to GPIO_IN, unless strict_gpiod is set */
+	if (strict_gpiod || fsel != RP1_FSEL_GPIO) {
 		rp1_set_dir(pin, RP1_DIR_INPUT);
 		rp1_set_fsel(pin, RP1_FSEL_GPIO);
 	}