[PATCH v5 4/6] phy: realtek: usb2: introduce reset controller struct

[Rustam Adilov <adilov@disroot.org>]

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_array_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 <misha.zavertkin@mail.ru>
Signed-off-by: Michael Zavertkin <misha.zavertkin@mail.ru>
Signed-off-by: Rustam Adilov <adilov@disroot.org>
---
 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 19297a42a841..aaa07a69224a 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 */
@@ -130,6 +131,7 @@ 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);
 
@@ -1059,6 +1070,11 @@ static int rtk_usb2phy_probe(struct platform_device *pdev)
 
 	rtk_phy->num_phy = phy_cfg->num_phy;
 
+	rtk_phy->phy_rst = devm_reset_control_array_get_optional_exclusive(dev);
+	if (IS_ERR(rtk_phy->phy_rst))
+		return dev_err_probe(dev, PTR_ERR(rtk_phy->phy_rst),
+				     "usb2 phy resets are not working\n");
+
 	ret = parse_phy_data(rtk_phy);
 	if (ret)
 		goto err;
-- 
2.53.0