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usb: dwc3: xilinx: Add gpio-reset support

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This patch adds a USB GPIO based reset for dwc3-xilinx driver. The PHY
needs to be reset after the completion of phy initialization. As part
of the reset, check for gpio-reset binding before toggling the pin.
This feature is advantageous when the user toggle GPIO to trigger the
ULPI-PHY reset.

Delay of milliseconds is added in between low and high to meet the setup
and hold time requirement of the reset. The reset-gpio error handling is
added for error notification.

Some GPIO controllers must be accessed using message-based buses, like
I2C or SPI, to address this problem, updates GPIO access with sleep API.

This reset is specific to the zynqMp.

Signed-off-by: Piyush Mehta <piyush.mehta@xilinx.com>
Link: https://lore.kernel.org/r/20220504075309.6244-3-piyush.mehta@xilinx.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Piyush Mehta 2022-05-04 13:23:09 +05:30 committed by Greg Kroah-Hartman
parent 1cda12b15d
commit ca05b38252
1 changed files with 17 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

17
drivers/usb/dwc3/dwc3-xilinx.c
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@ -13,6 +13,7 @@
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/dma-mapping.h>
#include <linux/of_gpio.h>
#include <linux/of_platform.h>
#include <linux/pm_runtime.h>
#include <linux/reset.h>
@ -98,6 +99,7 @@ static int dwc3_xlnx_init_zynqmp(struct dwc3_xlnx *priv_data)
{
struct device *dev = priv_data->dev;
struct reset_control *crst, *hibrst, *apbrst;
struct gpio_desc *reset_gpio;
struct phy *usb3_phy;
int ret = 0;
u32 reg;
@ -201,6 +203,21 @@ static int dwc3_xlnx_init_zynqmp(struct dwc3_xlnx *priv_data)
}
skip_usb3_phy:
/* ulpi reset via gpio-modepin or gpio-framework driver */
reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
if (IS_ERR(reset_gpio)) {
return dev_err_probe(dev, PTR_ERR(reset_gpio),
"Failed to request reset GPIO\n");
}
if (reset_gpio) {
/* Toggle ulpi to reset the phy. */
gpiod_set_value_cansleep(reset_gpio, 1);
usleep_range(5000, 10000);
gpiod_set_value_cansleep(reset_gpio, 0);
usleep_range(5000, 10000);
}
/*
* This routes the USB DMA traffic to go through FPD path instead
* of reaching DDR directly. This traffic routing is needed to