Re: [PATCH v4 2/2] arm: rk3399: usb2phy: phy-rockchip-inno-usb2.c: Implement operations for the 480MHz usb2phy clock in rk3399.

[Xavier Drudis Ferran <xdrudis@tinet.cat>]

This clock has no users but appears in a phandle list used by
ehci-generic.c to bulk enable it. The phandle list comes from linux,
where it is needed for suspend/resume to work [1].

My tests give the same results with or without this patch, but Marek
Vasut found it weird to declare an empty clk_ops[2].

So I adapted the code from linux 6.1-rc8 so that it hopefully works
if it ever has some user. For now, without real users, it seems to
at least not give any errors.

Links: [1] https://lkml.kernel.org/lkml/1731551.Q6cHK6n5ZM@phil/T/
       [2] https://patchwork.ozlabs.org/project/uboot/patch/Y5IWpjYLB4aXMy9o@localhost/#3018135
       
Cc: Simon Glass <sjg@chromium.org>
Cc: Philipp Tomsich <philipp.tomsich@vrull.eu>
Cc: Kever Yang <kever.yang@rock-chips.com>
Cc: Lukasz Majewski <lukma@denx.de>
Cc: Sean Anderson <seanga2@gmail.com>
Cc: Marek Vasut <marex@denx.de>

Signed-off-by: Xavier Drudis Ferran <xdrudis@tinet.cat>
---
 drivers/phy/rockchip/phy-rockchip-inno-usb2.c | 79 ++++++++++++++++++-
 1 file changed, 77 insertions(+), 2 deletions(-)

diff --git a/drivers/phy/rockchip/phy-rockchip-inno-usb2.c b/drivers/phy/rockchip/phy-rockchip-inno-usb2.c
index cfbdc7d87e..766dde11a6 100644
--- a/drivers/phy/rockchip/phy-rockchip-inno-usb2.c
+++ b/drivers/phy/rockchip/phy-rockchip-inno-usb2.c
@@ -55,6 +55,7 @@ struct rockchip_usb2phy_port_cfg {
 
 struct rockchip_usb2phy_cfg {
 	unsigned int reg;
+	struct usb2phy_reg	clkout_ctl;
 	const struct rockchip_usb2phy_port_cfg port_cfgs[USB2PHY_NUM_PORTS];
 };
 
@@ -76,6 +77,18 @@ static inline int property_enable(void *reg_base,
 	return writel(val, reg_base + reg->offset);
 }
 
+static inline bool property_enabled(void *reg_base,
+				    const struct usb2phy_reg *reg)
+{
+	unsigned int tmp, orig;
+	unsigned int mask = GENMASK(reg->bitend, reg->bitstart);
+
+	orig = readl(reg_base + reg->offset);
+
+	tmp = (orig & mask) >> reg->bitstart;
+	return tmp != reg->disable;
+}
+
 static const
 struct rockchip_usb2phy_port_cfg *us2phy_get_port(struct phy *phy)
 {
@@ -168,7 +181,64 @@ static struct phy_ops rockchip_usb2phy_ops = {
 	.of_xlate = rockchip_usb2phy_of_xlate,
 };
 
+/**
+ * round_rate() - Adjust a rate to the exact rate a clock can provide.
+ * @clk:	The clock to manipulate.
+ * @rate:	Desidered clock rate in Hz.
+ *
+ * Return: rounded rate in Hz, or -ve error code.
+ */
+ulong rockchip_usb2phy_clk_round_rate(struct clk *clk, ulong rate)
+{
+	return 480000000;
+}
+
+/**
+ * enable() - Enable a clock.
+ * @clk:	The clock to manipulate.
+ *
+ * Return: zero on success, or -ve error code.
+ */
+int rockchip_usb2phy_clk_enable(struct clk *clk)
+{
+	struct udevice *parent = dev_get_parent(clk->dev);
+	struct rockchip_usb2phy *priv = dev_get_priv(parent);
+	const struct rockchip_usb2phy_cfg *phy_cfg = priv->phy_cfg;
+	int ret;
+
+	/* turn on 480m clk output if it is off */
+	if (!property_enabled(priv->reg_base, &phy_cfg->clkout_ctl)) {
+		ret = property_enable(priv->reg_base, &phy_cfg->clkout_ctl, true);
+		if (ret)
+			return ret;
+
+		/* waiting for the clk become stable */
+		usleep_range(1200, 1300);
+	}
+
+	return 0;
+}
+
+/**
+ * disable() - Disable a clock.
+ * @clk:	The clock to manipulate.
+ *
+ * Return: zero on success, or -ve error code.
+ */
+int rockchip_usb2phy_clk_disable(struct clk *clk)
+{
+	struct udevice *parent = dev_get_parent(clk->dev);
+	struct rockchip_usb2phy *priv = dev_get_priv(parent);
+	const struct rockchip_usb2phy_cfg *phy_cfg = priv->phy_cfg;
+
+	/* turn off 480m clk output */
+	return property_enable(priv->reg_base, &phy_cfg->clkout_ctl, false);
+}
+
 static struct clk_ops rockchip_usb2phy_clk_ops = {
+	.enable = rockchip_usb2phy_clk_enable,
+	.disable = rockchip_usb2phy_clk_disable,
+	.round_rate = rockchip_usb2phy_clk_round_rate
 };
 
 static int rockchip_usb2phy_probe(struct udevice *dev)
@@ -245,8 +315,11 @@ static int rockchip_usb2phy_bind(struct udevice *dev)
 
 	if (!ret) {
 		node = dev_ofnode(dev);
-		name = ofnode_get_name(node);
-		dev_dbg(dev, "clk for node %s\n", name);
+		name = "clk_usbphy_480m";
+		dev_read_string_index(dev, "clock-output-names", 0, &name);
+
+		dev_dbg(dev, "clk %s for node %s\n", name, ofnode_get_name(node));
+
 		ret = device_bind_driver_to_node(dev, "rockchip_usb2phy_clock",
 						 name, node, &usb2phy_dev);
 		if (ret) {
@@ -261,6 +334,7 @@ static int rockchip_usb2phy_bind(struct udevice *dev)
 static const struct rockchip_usb2phy_cfg rk3399_usb2phy_cfgs[] = {
 	{
 		.reg		= 0xe450,
+		.clkout_ctl	= { 0xe450, 4, 4, 1, 0 },
 		.port_cfgs	= {
 			[USB2PHY_PORT_OTG] = {
 				.phy_sus	= { 0xe454, 1, 0, 2, 1 },
@@ -282,6 +356,7 @@ static const struct rockchip_usb2phy_cfg rk3399_usb2phy_cfgs[] = {
 	},
 	{
 		.reg		= 0xe460,
+		.clkout_ctl	= { 0xe460, 4, 4, 1, 0 },
 		.port_cfgs	= {
 			[USB2PHY_PORT_OTG] = {
 				.phy_sus        = { 0xe464, 1, 0, 2, 1 },
-- 
2.20.1