netdev - [PATCH v3 1/5] net: phy: Add support for microchip SMI0 MDIO bus

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Date:   Fri,  8 May 2020 17:43:39 +0200
From:   Michael Grzeschik <m.grzeschik@...gutronix.de>
To:     andrew@...n.ch
Cc:     netdev@...r.kernel.org, f.fainelli@...il.com, davem@...emloft.net,
        kernel@...gutronix.de
Subject: [PATCH v3 1/5] net: phy: Add support for microchip SMI0 MDIO bus

From: Andrew Lunn <andrew@...n.ch>

SMI0 is a mangled version of MDIO. The main low level difference is
the MDIO C22 OP code is always 0, not 0x2 or 0x1 for Read/Write. The
read/write information is instead encoded in the PHY address.

Extend the bit-bang code to allow the op code to be overridden, but
default to normal C22 values. Add an extra compatible to the mdio-gpio
driver, and when this compatible is present, set the op codes to 0.

A higher level driver, sitting on top of the basic MDIO bus driver can
then implement the rest of the microchip SMI0 odderties.

Signed-off-by: Andrew Lunn <andrew@...n.ch>
Signed-off-by: Michael Grzeschik <m.grzeschik@...gutronix.de>
---
 drivers/net/phy/mdio-bitbang.c |  7 ++-----
 drivers/net/phy/mdio-gpio.c    | 13 +++++++++++++
 include/linux/mdio-bitbang.h   |  2 ++
 3 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/drivers/net/phy/mdio-bitbang.c b/drivers/net/phy/mdio-bitbang.c
index 5136275c8e7399..11255460ecb933 100644
--- a/drivers/net/phy/mdio-bitbang.c
+++ b/drivers/net/phy/mdio-bitbang.c
@@ -19,9 +19,6 @@
 #include <linux/types.h>
 #include <linux/delay.h>
 
-#define MDIO_READ 2
-#define MDIO_WRITE 1
-
 #define MDIO_C45 (1<<15)
 #define MDIO_C45_ADDR (MDIO_C45 | 0)
 #define MDIO_C45_READ (MDIO_C45 | 3)
@@ -158,7 +155,7 @@ static int mdiobb_read(struct mii_bus *bus, int phy, int reg)
 		reg = mdiobb_cmd_addr(ctrl, phy, reg);
 		mdiobb_cmd(ctrl, MDIO_C45_READ, phy, reg);
 	} else
-		mdiobb_cmd(ctrl, MDIO_READ, phy, reg);
+		mdiobb_cmd(ctrl, ctrl->op_c22_read, phy, reg);
 
 	ctrl->ops->set_mdio_dir(ctrl, 0);
 
@@ -189,7 +186,7 @@ static int mdiobb_write(struct mii_bus *bus, int phy, int reg, u16 val)
 		reg = mdiobb_cmd_addr(ctrl, phy, reg);
 		mdiobb_cmd(ctrl, MDIO_C45_WRITE, phy, reg);
 	} else
-		mdiobb_cmd(ctrl, MDIO_WRITE, phy, reg);
+		mdiobb_cmd(ctrl, ctrl->op_c22_write, phy, reg);
 
 	/* send the turnaround (10) */
 	mdiobb_send_bit(ctrl, 1);
diff --git a/drivers/net/phy/mdio-gpio.c b/drivers/net/phy/mdio-gpio.c
index 1b00235d7dc5b5..d85bc1a98647e2 100644
--- a/drivers/net/phy/mdio-gpio.c
+++ b/drivers/net/phy/mdio-gpio.c
@@ -27,6 +27,9 @@
 #include <linux/gpio/consumer.h>
 #include <linux/of_mdio.h>
 
+#define MDIO_READ 2
+#define MDIO_WRITE 1
+
 struct mdio_gpio_info {
 	struct mdiobb_ctrl ctrl;
 	struct gpio_desc *mdc, *mdio, *mdo;
@@ -132,6 +135,15 @@ static struct mii_bus *mdio_gpio_bus_init(struct device *dev,
 		new_bus->phy_ignore_ta_mask = pdata->phy_ignore_ta_mask;
 	}
 
+	if (dev->of_node &&
+	    of_device_is_compatible(dev->of_node, "microchip,mdio-smi0")) {
+		bitbang->ctrl.op_c22_read = 0;
+		bitbang->ctrl.op_c22_write = 0;
+	} else {
+		bitbang->ctrl.op_c22_read = MDIO_READ;
+		bitbang->ctrl.op_c22_write = MDIO_WRITE;
+	}
+
 	dev_set_drvdata(dev, new_bus);
 
 	return new_bus;
@@ -196,6 +208,7 @@ static int mdio_gpio_remove(struct platform_device *pdev)
 
 static const struct of_device_id mdio_gpio_of_match[] = {
 	{ .compatible = "virtual,mdio-gpio", },
+	{ .compatible = "microchip,mdio-smi0" },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, mdio_gpio_of_match);
diff --git a/include/linux/mdio-bitbang.h b/include/linux/mdio-bitbang.h
index 5d71e8a8500f5e..8ae0b383523371 100644
--- a/include/linux/mdio-bitbang.h
+++ b/include/linux/mdio-bitbang.h
@@ -33,6 +33,8 @@ struct mdiobb_ops {
 
 struct mdiobb_ctrl {
 	const struct mdiobb_ops *ops;
+	u8 op_c22_read;
+	u8 op_c22_write;
 };
 
 /* The returned bus is not yet registered with the phy layer. */
-- 
2.26.2