[PATCH v7 4/6] phy: realtek: usb2: introduce reset controller struct

In RTL9607C, there is so called "IP Enable Controller" which resemble
reset controller with reset lines and is used for various things like
USB, PCIE, GMAC and such.

Introduce the reset_control struct to this driver to handle deasserting
usb2 phy reset line.

Make use of the function devm_reset_control_get_optional_exclusive()
function to get the reset controller and since existing RTD SoCs don't
specify the resets we can have a cleaner code.

Since the vendor usb driver developed by Realtek doesn't assert the reset
line (or in their case clear the register bit), we can reasonably assume
reset_control_assert is not needed here.

Co-developed-by: Michael Zavertkin <[email protected]>
Signed-off-by: Michael Zavertkin <[email protected]>
Signed-off-by: Rustam Adilov <[email protected]>
---
 drivers/phy/realtek/phy-rtk-usb2.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/phy/realtek/phy-rtk-usb2.c b/drivers/phy/realtek/phy-rtk-usb2.c
index 5e483c853f02..2ddad7be7353 100644
--- a/drivers/phy/realtek/phy-rtk-usb2.c
+++ b/drivers/phy/realtek/phy-rtk-usb2.c
@@ -17,6 +17,7 @@
 #include <linux/sys_soc.h>
 #include <linux/mfd/syscon.h>
 #include <linux/phy/phy.h>
+#include <linux/reset.h>
 #include <linux/usb.h>
 
 /* GUSB2PHYACCn register */
@@ -128,6 +129,7 @@ struct rtk_phy {
 	struct phy_cfg *phy_cfg;
 	int num_phy;
 	struct phy_parameter *phy_parameter;
+	struct reset_control *phy_rst;
 
 	struct dentry *debug_dir;
 };
@@ -676,6 +678,15 @@ static int rtk_phy_init(struct phy *phy)
 	if (!rtk_phy)
 		return -EINVAL;
 
+	if (rtk_phy->phy_rst) {
+		ret = reset_control_deassert(rtk_phy->phy_rst);
+
+		if (ret)
+			return ret;
+
+		usleep_range(5000, 6000);
+	}
+
 	for (i = 0; i < rtk_phy->num_phy; i++)
 		ret = do_rtk_phy_init(rtk_phy, i);
 
@@ -1055,6 +1066,11 @@ static int rtk_usb2phy_probe(struct platform_device *pdev)
 
 	rtk_phy->num_phy = phy_cfg->num_phy;
 
+	rtk_phy->phy_rst = devm_reset_control_get_optional_exclusive(dev, NULL);
+	if (IS_ERR(rtk_phy->phy_rst))
+		return dev_err_probe(dev, PTR_ERR(rtk_phy->phy_rst),
+				     "usb2 phy reset is not working\n");
+
 	ret = parse_phy_data(rtk_phy);
 	if (ret)
 		goto err;
-- 
2.55.0