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@xxxxxxxxxx>
---
drivers/usb/dwc3/dwc3-xilinx.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/drivers/usb/dwc3/dwc3-xilinx.c b/drivers/usb/dwc3/dwc3-xilinx.c
index a6f3a9b..67b237c 100644
--- a/drivers/usb/dwc3/dwc3-xilinx.c
+++ b/drivers/usb/dwc3/dwc3-xilinx.c
@@ -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
--
2.7.4
