[PATCH v3 09/10] gpio-exar/8250-exar: Make set of exported GPIOs configurable

[Jan Kiszka <jan.kiszka@xxxxxxxxxxx>]

On the SIMATIC, IOT2040 only a single pin is exportable as GPIO, the
rest is required to operate the UART. To allow modeling this case,
expand the platform device data structure to specify a (consecutive) pin
subset for exporting by the gpio-exar driver.

Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
---
 drivers/gpio/gpio-exar.c            | 29 ++++++++++++++++++++---------
 drivers/tty/serial/8250/8250_exar.c | 14 +++++++++++---
 2 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/drivers/gpio/gpio-exar.c b/drivers/gpio/gpio-exar.c
index d13bf20b8639..8970f50e681e 100644
--- a/drivers/gpio/gpio-exar.c
+++ b/drivers/gpio/gpio-exar.c
@@ -31,6 +31,7 @@ struct exar_gpio_chip {
 	int index;
 	void __iomem *regs;
 	char name[20];
+	unsigned int first_pin;
 };
 
 static void exar_update(struct gpio_chip *chip, unsigned int reg, int val,
@@ -51,9 +52,10 @@ static void exar_update(struct gpio_chip *chip, unsigned int reg, int val,
 static int exar_set_direction(struct gpio_chip *chip, int direction,
 			      unsigned int offset)
 {
-	unsigned int addr = offset / 8 ?
+	struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
+	unsigned int addr = (offset + exar_gpio->first_pin) / 8 ?
 		EXAR_OFFSET_MPIOSEL_HI : EXAR_OFFSET_MPIOSEL_LO;
-	unsigned int bit  = offset % 8;
+	unsigned int bit  = (offset + exar_gpio->first_pin) % 8;
 
 	exar_update(chip, addr, direction, bit);
 	return 0;
@@ -73,18 +75,20 @@ static int exar_get(struct gpio_chip *chip, unsigned int reg)
 
 static int exar_get_direction(struct gpio_chip *chip, unsigned int offset)
 {
-	unsigned int addr = offset / 8 ?
+	struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
+	unsigned int addr = (offset + exar_gpio->first_pin) / 8 ?
 		EXAR_OFFSET_MPIOSEL_HI : EXAR_OFFSET_MPIOSEL_LO;
-	unsigned int bit  = offset % 8;
+	unsigned int bit  = (offset + exar_gpio->first_pin) % 8;
 
 	return !!(exar_get(chip, addr) & BIT(bit));
 }
 
 static int exar_get_value(struct gpio_chip *chip, unsigned int offset)
 {
-	unsigned int addr = offset / 8 ?
+	struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
+	unsigned int addr = (offset + exar_gpio->first_pin) / 8 ?
 		EXAR_OFFSET_MPIOLVL_HI : EXAR_OFFSET_MPIOLVL_LO;
-	unsigned int bit  = offset % 8;
+	unsigned int bit  = (offset + exar_gpio->first_pin) % 8;
 
 	return !!(exar_get(chip, addr) & BIT(bit));
 }
@@ -92,9 +96,10 @@ static int exar_get_value(struct gpio_chip *chip, unsigned int offset)
 static void exar_set_value(struct gpio_chip *chip, unsigned int offset,
 			   int value)
 {
-	unsigned int addr = offset / 8 ?
+	struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
+	unsigned int addr = (offset + exar_gpio->first_pin) / 8 ?
 		EXAR_OFFSET_MPIOLVL_HI : EXAR_OFFSET_MPIOLVL_LO;
-	unsigned int bit  = offset % 8;
+	unsigned int bit  = (offset + exar_gpio->first_pin) % 8;
 
 	exar_update(chip, addr, value, bit);
 }
@@ -115,6 +120,7 @@ static int gpio_exar_probe(struct platform_device *pdev)
 {
 	struct pci_dev *pcidev = to_pci_dev(pdev->dev.parent);
 	struct exar_gpio_chip *exar_gpio;
+	u32 first_pin, npins;
 	void __iomem *p;
 	int index, ret;
 
@@ -126,6 +132,10 @@ static int gpio_exar_probe(struct platform_device *pdev)
 	if (!p)
 		return -ENOMEM;
 
+	if (device_property_read_u32(&pdev->dev, "first_pin", &first_pin) < 0 ||
+	    device_property_read_u32(&pdev->dev, "npins", &npins) < 0)
+		return -EINVAL;
+
 	exar_gpio = devm_kzalloc(&pdev->dev, sizeof(*exar_gpio), GFP_KERNEL);
 	if (!exar_gpio)
 		return -ENOMEM;
@@ -143,9 +153,10 @@ static int gpio_exar_probe(struct platform_device *pdev)
 	exar_gpio->gpio_chip.get = exar_get_value;
 	exar_gpio->gpio_chip.set = exar_set_value;
 	exar_gpio->gpio_chip.base = -1;
-	exar_gpio->gpio_chip.ngpio = 16;
+	exar_gpio->gpio_chip.ngpio = npins;
 	exar_gpio->regs = p;
 	exar_gpio->index = index;
+	exar_gpio->first_pin = first_pin;
 
 	ret = devm_gpiochip_add_data(&pdev->dev,
 				     &exar_gpio->gpio_chip, exar_gpio);
diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
index ee4b142f3ed0..42e7c5149c07 100644
--- a/drivers/tty/serial/8250/8250_exar.c
+++ b/drivers/tty/serial/8250/8250_exar.c
@@ -14,6 +14,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/pci.h>
+#include <linux/property.h>
 #include <linux/serial_core.h>
 #include <linux/serial_reg.h>
 #include <linux/slab.h>
@@ -196,8 +197,14 @@ static void setup_gpio(struct pci_dev *pcidev, u8 __iomem *p)
 }
 
 static void *
-xr17v35x_register_gpio(struct pci_dev *pcidev)
+xr17v35x_register_gpio(struct pci_dev *pcidev, unsigned int first_pin,
+		       unsigned int npins)
 {
+	struct property_entry properties[] = {
+		PROPERTY_ENTRY_U32("first_pin", first_pin),
+		PROPERTY_ENTRY_U32("npins", npins),
+		{ }
+	};
 	struct platform_device *pdev;
 
 	pdev = platform_device_alloc("gpio_exar", PLATFORM_DEVID_AUTO);
@@ -207,7 +214,8 @@ xr17v35x_register_gpio(struct pci_dev *pcidev)
 	pdev->dev.parent = &pcidev->dev;
 	ACPI_COMPANION_SET(&pdev->dev, ACPI_COMPANION(&pcidev->dev));
 
-	if (platform_device_add(pdev) < 0) {
+	if (platform_device_add_properties(pdev, properties) < 0 ||
+	    platform_device_add(pdev) < 0) {
 		platform_device_put(pdev);
 		return NULL;
 	}
@@ -250,7 +258,7 @@ pci_xr17v35x_setup(struct exar8250 *priv, struct pci_dev *pcidev,
 
 		if (pcidev->vendor == PCI_VENDOR_ID_EXAR)
 			port->port.private_data =
-				xr17v35x_register_gpio(pcidev);
+				xr17v35x_register_gpio(pcidev, 0, 16);
 	}
 
 	return 0;
-- 
2.12.0

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