[PATCH v2 2/2] net: phy: dp83867: respect ti,clk-output-sel DT property

[Roland Hieber <rhi@pengutronix.de>]

On some boards it is necessary to configure the PHY to provide the
correct clock to the FEC.

This ports the rest of the following two kernel commits:

    | commit 9708fb630d19ee51ae3aeb3a533e3010da0e8570
    | Author: Wadim Egorov <w.egorov@phytec.de>
    | Date:   Mi 2018-02-14 17:07:11
    |
    |     net: phy: dp83867: Add binding for the CLK_OUT pin muxing option
    |
    |     The DP83867 has a muxing option for the CLK_OUT pin. It is possible
    |     to set CLK_OUT for different channels.
    |     Create a binding to select a specific clock for CLK_OUT pin.
    |
    |     Signed-off-by: Wadim Egorov <w.egorov@phytec.de>
    |     Signed-off-by: Daniel Schultz <d.schultz@phytec.de>
    |     Reviewed-by: Andrew Lunn <andrew@lunn.ch>
    |     Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
    |     Signed-off-by: David S. Miller <davem@davemloft.net>
    |
    | commit 13c83cf8af0dcc6103982b4dc0b70826f0b54f21
    | Author: Trent Piepho <tpiepho@impinj.com>
    | Date:   Mi 2019-05-22 18:43:22
    |
    |     net: phy: dp83867: Add ability to disable output clock
    |
    |     Generally, the output clock pin is only used for testing and only serves
    |     as a source of RF noise after this.  It could be used to daisy-chain
    |     PHYs, but this is uncommon.  Since the PHY can disable the output, make
    |     doing so an option.  I do this by adding another enumeration to the
    |     allowed values of ti,clk-output-sel.
    |
    |     The code was not using the value DP83867_CLK_O_SEL_REF_CLK as one might
    |     expect: to select the REF_CLK as the output.  Rather it meant "keep
    |     clock output setting as is", which, depending on PHY strapping, might
    |     not be outputting REF_CLK.
    |
    |     Change this so DP83867_CLK_O_SEL_REF_CLK means enable REF_CLK output.
    |     Omitting the property will leave the setting as is (which was the
    |     previous behavior in this case).
    |
    |     Out of range values were silently converted into
    |     DP83867_CLK_O_SEL_REF_CLK.  Change this so they generate an error.
    |
    |     Cc: Andrew Lunn <andrew@lunn.ch>
    |     Cc: Florian Fainelli <f.fainelli@gmail.com>
    |     Cc: Heiner Kallweit <hkallweit1@gmail.com>
    |     Signed-off-by: Trent Piepho <tpiepho@impinj.com>
    |     Reviewed-by: Andrew Lunn <andrew@lunn.ch>
    |     Signed-off-by: David S. Miller <davem@davemloft.net>

Link: https://git.kernel.org/torvalds/c/9708fb630d19ee51ae3a
Link: https://git.kernel.org/torvalds/c/13c83cf8af0dcc610398
Signed-off-by: Roland Hieber <rhi@pengutronix.de>
---
v1 -> v2:
 * correctly use indirect write instead of direct write with the newly
   introduced helper function

PATCH v1: https://lore.barebox.org/barebox/20230601105710.hsslzy2s25pzcta3@pengutronix.de

 drivers/net/phy/dp83867.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/drivers/net/phy/dp83867.c b/drivers/net/phy/dp83867.c
index 375dcd075308..d8109172dfa5 100644
--- a/drivers/net/phy/dp83867.c
+++ b/drivers/net/phy/dp83867.c
@@ -96,6 +96,9 @@
 
 #define DP83867_IO_MUX_CFG_IO_IMPEDANCE_MAX	0x0
 #define DP83867_IO_MUX_CFG_IO_IMPEDANCE_MIN	0x1f
+#define DP83867_IO_MUX_CFG_CLK_O_DISABLE	BIT(6)
+#define DP83867_IO_MUX_CFG_CLK_O_SEL_MASK	(0x1f << 8)
+#define DP83867_IO_MUX_CFG_CLK_O_SEL_SHIFT	8
 
 /* CFG4 bits */
 #define DP83867_CFG4_PORT_MIRROR_EN		BIT(0)
@@ -113,6 +116,8 @@ struct dp83867_private {
 	int io_impedance;
 	int port_mirroring;
 	bool rxctrl_strap_quirk;
+	bool set_clk_output;
+	u32 clk_output_sel;
 };
 
 static int dp83867_read_status(struct phy_device *phydev)
@@ -174,6 +179,22 @@ static int dp83867_of_init(struct phy_device *phydev)
 	dp83867->io_impedance = -EINVAL;
 
 	/* Optional configuration */
+	ret = of_property_read_u32(of_node, "ti,clk-output-sel",
+				   &dp83867->clk_output_sel);
+	/* If not set, keep default */
+	if (!ret) {
+		dp83867->set_clk_output = true;
+		/* Valid values are 0 to DP83867_CLK_O_SEL_REF_CLK or
+		 * DP83867_CLK_O_SEL_OFF.
+		 */
+		if (dp83867->clk_output_sel > DP83867_CLK_O_SEL_REF_CLK &&
+		    dp83867->clk_output_sel != DP83867_CLK_O_SEL_OFF) {
+			dev_err(&phydev->dev, "ti,clk-output-sel value %u out of range\n",
+				   dp83867->clk_output_sel);
+			return -EINVAL;
+		}
+	}
+
 	if (of_property_read_bool(of_node, "ti,max-output-impedance"))
 		dp83867->io_impedance = DP83867_IO_MUX_CFG_IO_IMPEDANCE_MAX;
 	else if (of_property_read_bool(of_node, "ti,min-output-impedance"))
@@ -308,6 +329,22 @@ static int dp83867_config_init(struct phy_device *phydev)
 	if (dp83867->port_mirroring != DP83867_PORT_MIRROING_KEEP)
 		dp83867_config_port_mirroring(phydev);
 
+	/* Clock output selection if muxing property is set */
+	if (dp83867->set_clk_output) {
+		u16 mask = DP83867_IO_MUX_CFG_CLK_O_DISABLE;
+
+		if (dp83867->clk_output_sel == DP83867_CLK_O_SEL_OFF) {
+			val = DP83867_IO_MUX_CFG_CLK_O_DISABLE;
+		} else {
+			mask |= DP83867_IO_MUX_CFG_CLK_O_SEL_MASK;
+			val = dp83867->clk_output_sel <<
+				DP83867_IO_MUX_CFG_CLK_O_SEL_SHIFT;
+		}
+
+		phy_modify_mmd_indirect(phydev, DP83867_IO_MUX_CFG,
+				DP83867_DEVADDR, mask, val);
+	}
+
 	return 0;
 }
 
-- 
2.39.2