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net: phy: mdio-gpio: Add platform_data support for phy_mask

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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.

v2
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Andrew Lunn 2018-12-08 16:12:12 +01:00 committed by David S. Miller
parent 97ef7b4c55
commit 04fa26bab0
3 changed files with 19 additions and 0 deletions
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1
MAINTAINERS
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@ -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

5
drivers/net/phy/mdio-gpio.c
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@ -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;

13
include/linux/platform_data/mdio-gpio.h Normal file
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@ -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 {
u32 phy_mask;
};
#endif /* __LINUX_MDIO_GPIO_PDATA_H */