phy: realtek: usb: add new driver for the Realtek RTD SoC USB 2.0 PHY

Realtek DHC (digital home center) RTD SoCs support DWC3 XHCI USB
controller. Added the driver to drive the USB 2.0 PHY transceivers.

Note: New driver,remove the port status notification on legacy USB PHY.
Use the generic PHY to notify the usb device connect and disconnect.
To avoid using these PHYs would require describing the very same
PHY using both the generic "phy" property and the deprecated "usb-phy"
property.

Signed-off-by: Stanley Chang <stanley_chang@realtek.com>
Link: https://lore.kernel.org/r/20231213031203.4911-2-stanley_chang@realtek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

phy: realtek: Replace of_device.h with explicit includes

The DT of_device.h and of_platform.h date back to the separate
of_platform_bus_type before it as merged into the regular platform bus.
As part of that merge prepping Arm DT support 13 years ago, they
"temporarily" include each other and pull in various other headers. In
preparation to fix this, adjust the includes for what is actually needed.

of_device.h isn't needed, but platform_device.h was implicitly included by
it.

Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20231010205701.1585026-1-robh@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>

phy: realtek: usb: Drop unnecessary error check for debugfs_create_dir()

Both debugfs_create_dir() and debugfs_create_file() return ERR_PTR
and never return NULL.

As Greg suggested, this patch removes the error checking for
debugfs_create_dir in phy-rtk-usb2.c and phy-rtk-usb3.c. This is because
the DebugFS kernel API is developed in a way that the caller can safely
ignore the errors that occur during the creation of DebugFS nodes. The
debugfs APIs have a IS_ERR() judge in start_creating() which can handle it
gracefully. So these checks are unnecessary.

Fixes: 134e6d25f6bd ("phy: realtek: usb: Add driver for the Realtek SoC USB 2.0 PHY")
Fixes: adda6e82a7de ("phy: realtek: usb: Add driver for the Realtek SoC USB 3.0 PHY")
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20230901075231.1368947-1-ruanjinjie@huawei.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

phy: realtek: usb: add the error handler for nvmem_cell_read

There are following smatch warning:
drivers/phy/realtek/phy-rtk-usb2.c:901 get_phy_data_by_efuse()
error: 'buf' dereferencing possible ERR_PTR()
drivers/phy/realtek/phy-rtk-usb2.c:942 get_phy_data_by_efuse()
error: 'buf' dereferencing possible ERR_PTR()

drivers/phy/realtek/phy-rtk-usb3.c:460
get_phy_data_by_efuse() error: 'buf' dereferencing possible ERR_PTR()

The nvmem_cell_read may fail to read. So, driver must handle failure cases.

Fixes: 134e6d25f6bd ("phy: realtek: usb: Add driver for the Realtek SoC USB 2.0 PHY")
Fixes: adda6e82a7de ("phy: realtek: usb: Add driver for the Realtek SoC USB 3.0 PHY")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-phy/e7ff2870-c30c-4d8d-a7a9-d2d6a4962eb5@kadam.mountain/
Signed-off-by: Stanley Chang <stanley_chang@realtek.com>
Link: https://lore.kernel.org/r/20230801071509.20096-1-stanley_chang@realtek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

phy: realtek: usb: Add driver for the Realtek SoC USB 2.0 PHY

Realtek DHC (digital home center) RTD SoCs support DWC3 XHCI USB
controller. Added the driver to drive the USB 2.0 PHY transceivers.

Signed-off-by: Stanley Chang <stanley_chang@realtek.com>
Link: https://lore.kernel.org/r/20230725033318.8361-2-stanley_chang@realtek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>