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SubjectRe: [PATCH v2 2/2] usb: misc: usb5744: Add support for USB hub controller
On Tue, Feb 09, 2021 at 11:48:10AM +0100, Michal Simek wrote:
> From: Piyush Mehta <piyush.mehta@xilinx.com>
>
> This patch adds a USB GPIO based hub reset for USB5744 hub. This usb5744
> driver trigger hub reset signal after soft reset or core Reset. The HUB
> needs to be resetted after completion of phy initialization. After the
> toggling of gpio, hub configure using i2c usb attached command.
>
> USB5744 hub can be used without any I2C connection, is handled by a
> simple platform device driver.
>
> As part of the reset, sets the direction of the pin to output before
> toggling the pin. Delay of millisecond 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>
> Signed-off-by: Michal Simek <michal.simek@xilinx.com>
> ---
>
> Changes in v2:
> - s/USB_USB5744/USB_HUB_USB5744/g
> - Fix order in Makefile and Kconfig
>
> MAINTAINERS | 1 +
> drivers/usb/misc/Kconfig | 9 +++
> drivers/usb/misc/Makefile | 1 +
> drivers/usb/misc/usb5744.c | 115 +++++++++++++++++++++++++++++++++++++
> 4 files changed, 126 insertions(+)
> create mode 100644 drivers/usb/misc/usb5744.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 7439471b5d37..56d1fcdd24f6 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2706,6 +2706,7 @@ F: drivers/edac/synopsys_edac.c
> F: drivers/i2c/busses/i2c-cadence.c
> F: drivers/i2c/busses/i2c-xiic.c
> F: drivers/mmc/host/sdhci-of-arasan.c
> +F: drivers/usb/misc/usb5744.c
> N: zynq
> N: xilinx
>
> diff --git a/drivers/usb/misc/Kconfig b/drivers/usb/misc/Kconfig
> index 8f1144359012..9995a5701fd9 100644
> --- a/drivers/usb/misc/Kconfig
> +++ b/drivers/usb/misc/Kconfig
> @@ -255,6 +255,15 @@ config USB_HSIC_USB4604
> help
> This option enables support for SMSC USB4604 HSIC to USB 2.0 Driver.
>
> +config USB_HUB_USB5744
> + tristate "Microchip USB5744 Hub driver"
> + depends on I2C
> + depends on GPIOLIB
> + help
> + This option enables support for Microchip USB5744 Hub. This driver
> + optionally reset the hub using gpio pin and configure hub via i2c if
> + connected.
> +
> config USB_LINK_LAYER_TEST
> tristate "USB Link Layer Test driver"
> help
> diff --git a/drivers/usb/misc/Makefile b/drivers/usb/misc/Makefile
> index 5f4e598573ab..fbb9adf08f8c 100644
> --- a/drivers/usb/misc/Makefile
> +++ b/drivers/usb/misc/Makefile
> @@ -27,6 +27,7 @@ obj-$(CONFIG_USB_YUREX) += yurex.o
> obj-$(CONFIG_USB_HUB_USB251XB) += usb251xb.o
> obj-$(CONFIG_USB_HSIC_USB3503) += usb3503.o
> obj-$(CONFIG_USB_HSIC_USB4604) += usb4604.o
> +obj-$(CONFIG_USB_HUB_USB5744) += usb5744.o
> obj-$(CONFIG_USB_CHAOSKEY) += chaoskey.o
>
> obj-$(CONFIG_USB_SISUSBVGA) += sisusbvga/
> diff --git a/drivers/usb/misc/usb5744.c b/drivers/usb/misc/usb5744.c
> new file mode 100644
> index 000000000000..729b76345c69
> --- /dev/null
> +++ b/drivers/usb/misc/usb5744.c
> @@ -0,0 +1,115 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Driver for the Microchip USB5744 4-port hub.
> + *
> + * Copyright (c) 2021 Xilinx, Inc.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/platform_device.h>
> +
> +static int usb5744_init_hw(struct device *dev)
> +{
> + struct gpio_desc *reset_gpio;
> +
> + reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
> + if (IS_ERR(reset_gpio)) {
> + dev_err(dev, "Failed to bind reset gpio");
> + return -ENODEV;
> + }
> +
> + if (reset_gpio) {
> + /* Toggle RESET_N to reset the hub. */
> + gpiod_set_value(reset_gpio, 0);
> + usleep_range(5, 20); /* trstia */
> + gpiod_set_value(reset_gpio, 1);
> + usleep_range(5000, 10000); /* tcsh */
> + }
> +
> + return 0;
> +}
> +
> +static int usb5744_i2c_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct device *dev = &client->dev;
> + int ret;
> +
> + /* Trigger gpio reset to the hub. */
> + ret = usb5744_init_hw(dev);
> + if (ret)
> + return ret;
> +
> + /* Send SMBus command to boot hub. */
> + ret = i2c_smbus_write_word_data(client, 0xAA, swab16(0x5600));
> + if (ret < 0)
> + dev_err(dev, "Sending boot command failed");
> +
> + return ret;
> +}
> +
> +static int usb5744_platform_probe(struct platform_device *pdev)
> +{
> + /* Trigger gpio reset to the hub. */
> + return usb5744_init_hw(&pdev->dev);
> +}
> +
> +static const struct i2c_device_id usb5744_id[] = {
> + { "usb5744", 0 },
> + {}
> +};
> +MODULE_DEVICE_TABLE(i2c, usb5744_id);
> +
> +static struct i2c_driver usb5744_i2c_driver = {
> + .driver = {
> + .name = "usb5744",
> + },
> + .probe = usb5744_i2c_probe,
> + .id_table = usb5744_id,
> +};
> +
> +static const struct of_device_id usb5744_platform_id[] = {
> + { .compatible = "microchip,usb5744", },
> + { }
> +};
> +
> +static struct platform_driver usb5744_platform_driver = {
> + .driver = {
> + .name = "microchip,usb5744",
> + .of_match_table = usb5744_platform_id,
> + },
> + .probe = usb5744_platform_probe,
> +};
> +
> +static int __init usb5744_init(void)
> +{
> + int err;
> +
> + err = i2c_add_driver(&usb5744_i2c_driver);
> + if (err != 0)
> + pr_err("usb5744: Failed to register I2C driver: %d\n", err);
> +
> + err = platform_driver_register(&usb5744_platform_driver);
> + if (err != 0)
> + pr_err("usb5744: Failed to register platform driver: %d\n",
> + err);
> + return 0;

So, no matter how many failures happen, you still say everything is good
and continue on with loading the module?

Please don't.

thanks,

greg k-h

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