linux-kernel - [PATCH v3 2/2] gpio: mlxbf3: Support add_pin

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Date:   Thu, 17 Aug 2023 21:21:11 -0400
From:   Asmaa Mnebhi <asmaa@...dia.com>
To:     <andy.shevchenko@...il.com>, <linux-gpio@...r.kernel.org>,
        <linus.walleij@...aro.org>, <bgolaszewski@...libre.com>,
        <brgl@...ev.pl>, <linux-kernel@...r.kernel.org>
CC:     Asmaa Mnebhi <asmaa@...dia.com>
Subject: [PATCH v3 2/2] gpio: mlxbf3: Support add_pin_ranges()

Support add_pin_ranges() so that pinctrl_gpio_request() can be called.
The GPIO value is not modified when the user runs the "gpioset" tool.
This is because when gpiochip_generic_request is invoked by the gpio-mlxbf3
driver, "pin_ranges" is empty so it skips "pinctrl_gpio_request()".
pinctrl_gpio_request() is essential in the code flow because it changes the
mux value so that software has control over modifying the GPIO value.
Adding add_pin_ranges() creates a dependency on the pinctrl-mlxbf3.c driver.

Fixes: cd33f216d24 ("gpio: mlxbf3: Add gpio driver support")
Signed-off-by: Asmaa Mnebhi <asmaa@...dia.com>
---
v2->v3:
- Replace boolean logic by clear switch statement logic in
  mlxbf3_gpio_add_pin_ranges()
v1->v2:
- Cleanup mlxbf3_gpio_add_pin_ranges()

 drivers/gpio/gpio-mlxbf3.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/gpio/gpio-mlxbf3.c b/drivers/gpio/gpio-mlxbf3.c
index e30cee108986..436b0bb5ebb1 100644
--- a/drivers/gpio/gpio-mlxbf3.c
+++ b/drivers/gpio/gpio-mlxbf3.c
@@ -19,6 +19,8 @@
  * gpio[1]: HOST_GPIO32->HOST_GPIO55
  */
 #define MLXBF3_GPIO_MAX_PINS_PER_BLOCK 32
+#define MLXBF3_GPIO_MAX_PINS_BLOCK0    MLXBF3_GPIO_MAX_PINS_PER_BLOCK
+#define MLXBF3_GPIO_MAX_PINS_BLOCK1    24
 
 /*
  * fw_gpio[x] block registers and their offset
@@ -158,6 +160,26 @@ static const struct irq_chip gpio_mlxbf3_irqchip = {
 	GPIOCHIP_IRQ_RESOURCE_HELPERS,
 };
 
+static int mlxbf3_gpio_add_pin_ranges(struct gpio_chip *chip)
+{
+	unsigned int id;
+
+	switch(chip->ngpio) {
+	case MLXBF3_GPIO_MAX_PINS_BLOCK0:
+		id = 0;
+		break;
+	case MLXBF3_GPIO_MAX_PINS_BLOCK1:
+		id = 1;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return gpiochip_add_pin_range(chip, "MLNXBF34:00",
+			chip->base, id * MLXBF3_GPIO_MAX_PINS_PER_BLOCK,
+			chip->ngpio);
+}
+
 static int mlxbf3_gpio_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -197,6 +219,7 @@ static int mlxbf3_gpio_probe(struct platform_device *pdev)
 	gc->request = gpiochip_generic_request;
 	gc->free = gpiochip_generic_free;
 	gc->owner = THIS_MODULE;
+	gc->add_pin_ranges = mlxbf3_gpio_add_pin_ranges;
 
 	irq = platform_get_irq(pdev, 0);
 	if (irq >= 0) {
@@ -243,6 +266,7 @@ static struct platform_driver mlxbf3_gpio_driver = {
 };
 module_platform_driver(mlxbf3_gpio_driver);
 
+MODULE_SOFTDEP("pre: pinctrl-mlxbf3");
 MODULE_DESCRIPTION("NVIDIA BlueField-3 GPIO Driver");
 MODULE_AUTHOR("Asmaa Mnebhi <asmaa@...dia.com>");
 MODULE_LICENSE("Dual BSD/GPL");
-- 
2.30.1