[PATCH 2/2] gpio: modepin: Add driver support for modepin GPIO controller

[Piyush Mehta <piyush.mehta@xilinx.com>]

This patch adds support for the mode pin GPIO controller. GPIO Modepin
driver set and get the value and status of the PS_MODE pin, based on
device-tree pin configuration. These 4-bits boot-mode pins are dedicated
configurable as input/output. After the stabilization of the system,
these mode pins are sampled.

Signed-off-by: Piyush Mehta <piyush.mehta@xilinx.com>
---
 drivers/gpio/Kconfig               |  12 +++
 drivers/gpio/Makefile              |   1 +
 drivers/gpio/gpio-zynqmp-modepin.c | 154 +++++++++++++++++++++++++++++++++++++
 3 files changed, 167 insertions(+)
 create mode 100644 drivers/gpio/gpio-zynqmp-modepin.c

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 1dd0ec6..30e0dbf 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -755,6 +755,18 @@ config GPIO_ZYNQ
 	help
 	  Say yes here to support Xilinx Zynq GPIO controller.
 
+config GPIO_ZYNQMP_MODEPIN
+	tristate "ZynqMP ps-mode pin gpio configuration driver"
+	depends on ZYNQMP_FIRMWARE
+	default ZYNQMP_FIRMWARE
+	help
+	  Say yes here to support the ZynqMP ps-mode pin gpio configuration
+	  driver.
+
+	  This ps-mode pin gpio driver is based on GPIO framework, PS_MODE
+	  is 4-bits boot mode pins. It sets and gets the status of
+	  the ps-mode pin. Every pin can be configured as input/output.
+
 config GPIO_LOONGSON1
 	tristate "Loongson1 GPIO support"
 	depends on MACH_LOONGSON32
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index d7c81e1..62bfa73 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -182,3 +182,4 @@ obj-$(CONFIG_GPIO_XRA1403)		+= gpio-xra1403.o
 obj-$(CONFIG_GPIO_XTENSA)		+= gpio-xtensa.o
 obj-$(CONFIG_GPIO_ZEVIO)		+= gpio-zevio.o
 obj-$(CONFIG_GPIO_ZYNQ)			+= gpio-zynq.o
+obj-$(CONFIG_GPIO_ZYNQMP_MODEPIN)	+= gpio-zynqmp-modepin.o
diff --git a/drivers/gpio/gpio-zynqmp-modepin.c b/drivers/gpio/gpio-zynqmp-modepin.c
new file mode 100644
index 0000000..27052f0
--- /dev/null
+++ b/drivers/gpio/gpio-zynqmp-modepin.c
@@ -0,0 +1,154 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for the ps-mode pin configuration.
+ *
+ * Copyright (c) 2021 Xilinx, Inc.
+ */
+
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/gpio/driver.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/firmware/xlnx-zynqmp.h>
+
+#define MODE_PINS			4
+#define GET_OUTEN_PIN(pin)		(1U << (pin))
+
+/*
+ * modepin_gpio_get_value - Get the state of the specified pin of GPIO device
+ * @chip:	gpio_chip instance to be worked on
+ * @pin:	gpio pin number within the device
+ *
+ * This function reads the state of the specified pin of the GPIO device.
+ *
+ * Return: 0 if the pin is low, 1 if pin is high, -EINVAL wrong pin configured
+ *         or error value.
+ */
+static int modepin_gpio_get_value(struct gpio_chip *chip, unsigned int pin)
+{
+	u32 out_en;
+	u32 regval = 0;
+	int ret;
+
+	out_en = GET_OUTEN_PIN(pin);
+
+	ret = zynqmp_pm_bootmode_read(&regval);
+	if (ret) {
+		pr_err("modepin: get value err %d\n", ret);
+		return ret;
+	}
+
+	return (out_en & (regval >> 8U)) ? 1 : 0;
+}
+
+/*
+ * modepin_gpio_set_value - Modify the state of the pin with specified value
+ * @chip:	gpio_chip instance to be worked on
+ * @pin:	gpio pin number within the device
+ * @state:	value used to modify the state of the specified pin
+ *
+ * Return:	None.
+ */
+static void modepin_gpio_set_value(struct gpio_chip *chip, unsigned int pin,
+				   int state)
+{
+	u32 out_en;
+	u32 bootpin_val = 0;
+	int ret;
+
+	out_en = GET_OUTEN_PIN(pin);
+	state = state != 0 ? out_en : 0;
+	bootpin_val = (state << (8U)) | out_en;
+
+	/* Configure bootpin value */
+	ret = zynqmp_pm_bootmode_write(bootpin_val);
+	if (ret)
+		pr_err("modepin: %s failed\n", __func__);
+}
+
+/*
+ * modepin_gpio_dir_in - Set the direction of the specified GPIO pin as input
+ * @chip:	gpio_chip instance to be worked on
+ * @pin:	gpio pin number within the device
+ *
+ * Return: 0 always
+ */
+static int modepin_gpio_dir_in(struct gpio_chip *chip, unsigned int pin)
+{
+	return 0;
+}
+
+/*
+ * modepin_gpio_dir_out - Set the direction of the specified GPIO pin as output
+ * @chip:	gpio_chip instance to be worked on
+ * @pin:	gpio pin number within the device
+ * @state:	value to be written to specified pin
+ *
+ * Return: 0 always
+ */
+static int modepin_gpio_dir_out(struct gpio_chip *chip, unsigned int pin,
+				int state)
+{
+	return 0;
+}
+
+/*
+ * modepin_gpio_probe - Initialization method for modepin_gpio
+ * @pdev:		platform device instance
+ *
+ * Return: 0 on success, negative error otherwise.
+ */
+static int modepin_gpio_probe(struct platform_device *pdev)
+{
+	struct gpio_chip *chip;
+	int status;
+
+	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, chip);
+
+	/* configure the gpio chip */
+	chip->base = -1;
+	chip->ngpio = MODE_PINS;
+	chip->owner = THIS_MODULE;
+	chip->parent = &pdev->dev;
+	chip->get = modepin_gpio_get_value;
+	chip->set = modepin_gpio_set_value;
+	chip->direction_input = modepin_gpio_dir_in;
+	chip->direction_output = modepin_gpio_dir_out;
+	chip->label = dev_name(&pdev->dev);
+
+	/* modepin gpio registration */
+	status = devm_gpiochip_add_data(&pdev->dev, chip, chip);
+	if (status)
+		dev_err_probe(&pdev->dev, status,
+			      "Failed to add GPIO chip\n");
+
+	return status;
+}
+
+static const struct of_device_id modepin_platform_id[] = {
+	{ .compatible = "xlnx,zynqmp-gpio-modepin", },
+	{ }
+};
+
+static struct platform_driver modepin_platform_driver = {
+	.driver = {
+		.name = "modepin-gpio",
+		.of_match_table = modepin_platform_id,
+	},
+	.probe = modepin_gpio_probe,
+};
+
+module_platform_driver(modepin_platform_driver);
+
+MODULE_AUTHOR("Piyush Mehta <piyush.mehta@xilinx.com>");
+MODULE_DESCRIPTION("ZynqMP Boot PS_MODE Configuration");
+MODULE_LICENSE("GPL v2");
-- 
2.7.4