From 68c654fa7a4c854ac71406d68b2e8f8571696d60 Mon Sep 17 00:00:00 2001
From: Ren Jianing <jianing.ren@rock-chips.com>
Date: Mon, 8 Jun 2020 19:01:10 +0800
Subject: [PATCH] phy: phy-rockchip-naneng-usb2: add Rref calibrate in tuning

This patch can change phy internal 45 Ohm resistance accord to
reference resistance. The larger the reference resistance, the
greater the internal resistance, and accordingly, high speed
eye diagram amplitude will become lower.

The maximum adjustable range of the reference is +-20% of the
default value (200 Ohm).

Signed-off-by: Ren Jianing <jianing.ren@rock-chips.com>
Change-Id: Ibd746283c06609b944fa2a148066ba0a661e761a
---
 .../phy/rockchip/phy-rockchip-naneng-usb2.c   | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/drivers/phy/rockchip/phy-rockchip-naneng-usb2.c b/drivers/phy/rockchip/phy-rockchip-naneng-usb2.c
index 446570227cca..1bfb569e9114 100644
--- a/drivers/phy/rockchip/phy-rockchip-naneng-usb2.c
+++ b/drivers/phy/rockchip/phy-rockchip-naneng-usb2.c
@@ -11,6 +11,7 @@
 #include <linux/extcon-provider.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/gpio/consumer.h>
 #include <linux/jiffies.h>
 #include <linux/kernel.h>
@@ -1464,6 +1465,7 @@ static int rockchip_usb2phy_remove(struct platform_device *pdev)
 static int rv1126_usb2phy_tuning(struct rockchip_usb2phy *rphy)
 {
 	int ret = 0;
+	u32 rcal, reg;
 
 	if (rphy->phy_cfg->reg == 0xff4c0000) {
 		/* set iddig interrupt filter time to 10ms */
@@ -1475,6 +1477,30 @@ static int rv1126_usb2phy_tuning(struct rockchip_usb2phy *rphy)
 		ret = regmap_write(rphy->grf, 0x1027c, 0x0f0f0100);
 		if (ret)
 			goto out;
+
+		reg = readl(rphy->base + 0x10);
+		/* Enable Rterm self calibration and wait for rcal trim done */
+		writel(reg & ~BIT(2), rphy->base + 0x10);
+		/*
+		 * If Rterm is disconnected, self calibration will fail and
+		 * rcal trim done will be set in about 3.5 us
+		 */
+		udelay(10);
+		if (readl(rphy->base + 0x34) & BIT(4)) {
+			dev_dbg(rphy->dev, "Rterm disconnected");
+		} else {
+			ret = readl_poll_timeout(rphy->base + 0x34, rcal,
+						 rcal & BIT(4),
+						 100, 600);
+			if (ret == -ETIMEDOUT)
+				dev_err(rphy->dev, "Rterm calibration timeout");
+			else
+				/* Use rcal out calibration code */
+				reg = (reg & ~(0x0f << 3)) |
+				      ((rcal & 0x0f) << 3);
+		}
+		/* Disable Rterm self calibration */
+		writel(reg | BIT(2), rphy->base + 0x10);
 	}
 
 	if (rphy->phy_cfg->reg == 0xff4c8000) {