usb: misc: usb2244: add support for USB2 ultra fast sd controller

This patch adds a GPIO based usb-sd reset for USB2244 USB2 ultra fast
SD controller. This usb2244 driver trigger sd reset signal after soft
reset or core Reset. The SD needs to be resetted after completion of
phy initialization. After the toggling of gpio, controller gets out
form reset. USB2244 is a simple platform device driver.

As part of the reset, sets the direction of the pin to output before
toggling the pin. Delay of microseconds is added in between low and
high to meet the setup and hold time requirement of the reset.

Signed-off-by: Piyush Mehta <piyush.mehta@xilinx.com>

drivers/usb/misc/Kconfig

@@ -242,6 +242,14 @@ config USB_HUB_USB251XB
 	  parameters may be set in devicetree or platform data.
 	  Say Y or M here if you need to configure such a device via SMBus.
 
+config USB_USB2244
+	tristate "Microchip USB2244 Ultra Fast USB 2.0 SD driver"
+	depends on GPIOLIB
+	help
+	  This option enables support for Microchip USB2244 Ultra Fast USB 2.0
+	  SD controller. This driver reset the gpio pin makes controller out of
+	  reset.
+
 config USB_USB5744
 	tristate "Microchip USB5744 Hub driver"
 	depends on I2C

drivers/usb/misc/Makefile

@@ -25,6 +25,7 @@ obj-$(CONFIG_USB_USS720)		+= uss720.o
 obj-$(CONFIG_USB_SEVSEG)		+= usbsevseg.o
 obj-$(CONFIG_USB_YUREX)			+= yurex.o
 obj-$(CONFIG_USB_HUB_USB251XB)		+= usb251xb.o
+obj-$(CONFIG_USB_USB2244)		+= usb2244.o
 obj-$(CONFIG_USB_USB5744)		+= usb5744.o
 obj-$(CONFIG_USB_HSIC_USB3503)		+= usb3503.o
 obj-$(CONFIG_USB_HSIC_USB4604)		+= usb4604.o

drivers/usb/misc/usb2244.c

@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for the Microchip USB2244 Ultra Fast USB 2.0 Multi-Format,
+ * SD/MMC, and MS Flash Media Controllers
+ *
+ * Copyright (c) 2021 Xilinx, Inc.
+ */
+
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/gpio/consumer.h>
+#include <linux/platform_device.h>
+
+struct usb2244 {
+	struct gpio_desc *reset_gpio;
+};
+
+static int usb2244_init_hw(struct device *dev, struct usb2244 *data)
+{
+	data = devm_kzalloc(dev, sizeof(struct usb2244), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(data->reset_gpio)) {
+		dev_err_probe(dev, PTR_ERR(data->reset_gpio),
+			      "Failed to request reset GPIO %d, errcode",
+			      PTR_ERR(data->reset_gpio));
+		return PTR_ERR(data->reset_gpio);
+	}
+
+	/* Toggle RESET_N to reset the hub. */
+	gpiod_set_value_cansleep(data->reset_gpio, 0);
+	usleep_range(5, 10);
+	gpiod_set_value_cansleep(data->reset_gpio, 1);
+	msleep(5);
+
+	return 0;
+}
+
+static int usb2244_probe(struct platform_device *pdev)
+{
+	struct usb2244 *data = NULL;
+
+	/* Trigger gpio reset to the hub. */
+	return usb2244_init_hw(&pdev->dev, data);
+}
+
+static const struct of_device_id usb2244_of_match[] = {
+	{ .compatible = "microchip,usb2244", },
+	{ }
+};
+
+static struct platform_driver usb2244_driver = {
+	.driver = {
+		.name = "microchip,usb2244",
+		.of_match_table	= usb2244_of_match,
+	},
+	.probe = usb2244_probe,
+};
+
+module_platform_driver(usb2244_driver);
+
+MODULE_AUTHOR("Piyush Mehta <piyush.mehta@xilinx.com>");
+MODULE_DESCRIPTION("USB2244 Ultra Fast SD-Controller");
+MODULE_LICENSE("GPL v2");