Add USB2 pad power on and off API's for TEgra210 and provide its control
via soc ops. It can be used by operations like charger detect to power on
and off USB2 pad if needed.

Signed-off-by: Nagarjuna Kristam <redacted>
Acked-by: Thierry Reding <redacted>
---
V5:
 - Made tegra210_usb2_pad_power_on() and tegra210_usb2_pad_power_down() static.
---
V4:
 - No changes
---
V3:
 - Added Acked-by updates to commit message.
---
V2:
 - Patch re-based.
---
 drivers/phy/tegra/xusb-tegra210.c | 190 ++++++++++++++++++++++++++------------
 1 file changed, 133 insertions(+), 57 deletions(-)

diff --git a/drivers/phy/tegra/xusb-tegra210.c b/drivers/phy/tegra/xusb-tegra210.c
index 66bd461..2e5f71c 100644
--- a/drivers/phy/tegra/xusb-tegra210.c
+++ b/drivers/phy/tegra/xusb-tegra210.c

@@ -994,6 +994,128 @@ static int tegra210_xusb_padctl_id_override(struct tegra_xusb_padctl *padctl,
 	return 0;
 }
 
+static void tegra210_usb2_bias_pad_power_on(struct tegra_xusb_usb2_pad *pad)
+{
+	struct tegra_xusb_padctl *padctl = pad->base.padctl;
+	u32 value;
+
+	if (pad->enable++ > 0)
+		return;
+
+	dev_dbg(padctl->dev, "power on BIAS PAD & USB2 tracking\n");
+
+	if (clk_prepare_enable(pad->clk))
+		dev_warn(padctl->dev, "failed to enable BIAS PAD & USB2 tracking\n");