netdev - [PATCH net-next 1/2] net: phy: mdio-gpio: Add platform_data support for phy

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Message-Id: <1544104723-17857-2-git-send-email-andrew@lunn.ch>
Date:   Thu,  6 Dec 2018 14:58:42 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     David Miller <davem@...emloft.net>
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        netdev <netdev@...r.kernel.org>, Andrew Lunn <andrew@...n.ch>
Subject: [PATCH net-next 1/2] net: phy: mdio-gpio: Add platform_data support for phy_mask

It is sometimes necessary to instantiate a bit-banging MDIO bus as a
platform device, without the aid of device tree.

When device tree is being used, the bus is not scanned for devices,
only those devices which are in device tree are probed. Without device
tree, by default, all addresses on the bus are scanned. This may then
find a device which is not a PHY, e.g. a switch. And the switch may
have registers containing values which look like a PHY. So during the
scan, a PHY device is wrongly created.

After the bus has been registered, a search is made for
mdio_board_info structures which indicates devices on the bus, and the
driver which should be used for them. This is typically used to
instantiate Ethernet switches from platform drivers.  However, if the
scanning of the bus has created a PHY device at the same location as
indicated into the board info for a switch, the switch device is not
created, since the address is already busy.

This can be avoided by setting the phy_mask of the mdio bus. This mask
prevents addresses on the bus being scanned.

Signed-off-by: Andrew Lunn <andrew@...n.ch>
---
 MAINTAINERS                             |  1 +
 drivers/net/phy/mdio-gpio.c             |  5 +++++
 include/linux/platform_data/mdio-gpio.h | 13 +++++++++++++
 3 files changed, 19 insertions(+)
 create mode 100644 include/linux/platform_data/mdio-gpio.h

diff --git a/MAINTAINERS b/MAINTAINERS
index fb88b6863d10..9d3b899f9ba2 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5610,6 +5610,7 @@ F:	include/linux/of_net.h
 F:	include/linux/phy.h
 F:	include/linux/phy_fixed.h
 F:	include/linux/platform_data/mdio-bcm-unimac.h
+F:	include/linux/platform_data/mdio-gpio.h
 F:	include/trace/events/mdio.h
 F:	include/uapi/linux/mdio.h
 F:	include/uapi/linux/mii.h
diff --git a/drivers/net/phy/mdio-gpio.c b/drivers/net/phy/mdio-gpio.c
index 0fbcedcdf6e2..1e296dd4067a 100644
--- a/drivers/net/phy/mdio-gpio.c
+++ b/drivers/net/phy/mdio-gpio.c
@@ -24,6 +24,7 @@
 #include <linux/slab.h>
 #include <linux/interrupt.h>
 #include <linux/platform_device.h>
+#include <linux/platform_data/mdio-gpio.h>
 #include <linux/mdio-bitbang.h>
 #include <linux/mdio-gpio.h>
 #include <linux/gpio/consumer.h>
@@ -112,6 +113,7 @@ static struct mii_bus *mdio_gpio_bus_init(struct device *dev,
 					  struct mdio_gpio_info *bitbang,
 					  int bus_id)
 {
+	struct mdio_gpio_platform_data *pdata = dev_get_platdata(dev);
 	struct mii_bus *new_bus;
 
 	bitbang->ctrl.ops = &mdio_gpio_ops;
@@ -128,6 +130,9 @@ static struct mii_bus *mdio_gpio_bus_init(struct device *dev,
 	else
 		strncpy(new_bus->id, "gpio", MII_BUS_ID_SIZE);
 
+	if (pdata)
+		new_bus->phy_mask = pdata->phy_mask;
+
 	dev_set_drvdata(dev, new_bus);
 
 	return new_bus;
diff --git a/include/linux/platform_data/mdio-gpio.h b/include/linux/platform_data/mdio-gpio.h
new file mode 100644
index 000000000000..0417913aac3d
--- /dev/null
+++ b/include/linux/platform_data/mdio-gpio.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * MDIO-GPIO bus platform data structure
+ */
+
+#ifndef __LINUX_MDIO_GPIO_PDATA_H
+#define __LINUX_MDIO_GPIO_PDATA_H
+
+struct mdio_gpio_platform_data {
+	int phy_mask;
+};
+
+#endif /* __LINUX_MDIO_GPIO_PDATA_H */
-- 
2.19.1