When accessing an MDIO register using single-byte smbus accesses, we have to
perform 2 consecutive operations targeting the same address,
first accessing the MSB then the LSB of the 16 bit register:
read_1_byte(addr); <- returns MSB of register at address 'addr'
read_1_byte(addr); <- returns LSB
Some PHY devices present in SFP such as the Broadcom 5461 don't like
seeing foreign i2c transactions in-between these 2 smbus accesses, and
will return the MSB a second time when trying to read the LSB :
read_1_byte(addr); <- returns MSB
i2c_transaction_for_other_device_on_the_bus();
read_1_byte(addr); <- returns MSB again
Given the already fragile nature of accessing PHYs/SFPs with single-byte
smbus accesses, it's safe to say that this Broadcom PHY may not be the
only one acting like this.
Let's therefore hold the i2c bus lock while performing our smbus
transactions to avoid interleaved accesses.
Fixes: d4bd3aca33 ("net: mdio: mdio-i2c: Add support for single-byte SMBus operations")
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20251003070311.861135-1-maxime.chevallier@bootlin.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
PHYs that are within copper SFP modules have their MDIO bus accessible
through address 0x56 (usually) on the i2c bus. The MDIO-I2C bridge is
desgned for 16 bits accesses, but we can also perform 8bits accesses by
reading/writing the high and low bytes sequentially.
This commit adds support for this type of accesses, thus supporting
smbus controllers such as the one in the VSC8552.
This was only tested on Copper SFP modules that embed a Marvell 88e1111
PHY.
Tested-by: Sean Anderson <sean.anderson@linux.dev>
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20250322075745.120831-3-maxime.chevallier@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Commit 87e3bee0f2 ("net: mdio: i2c: Separate C22 and C45 transactions")
separated the non-rollball bus accessors, but left the rollball
accessors as is. As rollball accessors are clause 45, this results
in the rollball protocol being completely non-functional. Fix this.
Fixes: 87e3bee0f2 ("net: mdio: i2c: Separate C22 and C45 transactions")
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
The MDIO core should not pass a C45 request via the C22 API call any
more. So remove the tests from the drivers.
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The MDIO over I2C bus driver can perform both C22 and C45 transfers.
Create separate functions for each and register the C45 versions using
the new API calls.
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Some multigig SFPs from RollBall and Hilink do not expose functional
MDIO access to the internal PHY of the SFP via I2C address 0x56
(although there seems to be read-only clause 22 access on this address).
Instead these SFPs PHY can be accessed via I2C via the SFP Enhanced
Digital Diagnostic Interface - I2C address 0x51. The SFP_PAGE has to be
selected to 3 and the password must be filled with 0xff bytes for this
PHY communication to work.
This extends the mdio-i2c driver to support this protocol by adding a
special parameter to mdio_i2c_alloc function via which this RollBall
protocol can be selected.
Signed-off-by: Marek Behún <kabel@kernel.org>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
Move all the MDIO drivers and multiplexers into drivers/net/mdio. The
mdio core is however left in the phy directory, due to mutual
dependencies between the MDIO core and the PHY core.
Take this opportunity to sort the Kconfig based on the menuconfig
strings, and move the multiplexers to the end with a separating
comment.
v2:
Fix typo in commit message
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
