linux-kernel - Re: [PATCH net-next 2/2] net: mdio-mux: Add MDIO mux driver for Sophgo CV1800 SoCs

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Message-ID: <255j5pbi3pty5n3dmcalq4uhsoj37rsq5263fijn76o3vrkbs5@cctlwa5567om>
Date: Tue, 1 Jul 2025 08:36:12 +0800
From: Inochi Amaoto <inochiama@...il.com>
To: Alexander Sverdlin <alexander.sverdlin@...il.com>, 
	Inochi Amaoto <inochiama@...il.com>, Andrew Lunn <andrew+netdev@...n.ch>
Cc: netdev@...r.kernel.org, devicetree@...r.kernel.org, 
	sophgo@...ts.linux.dev, linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org, 
	Yixun Lan <dlan@...too.org>, Longbin Li <looong.bin@...il.com>
Subject: Re: [PATCH net-next 2/2] net: mdio-mux: Add MDIO mux driver for
 Sophgo CV1800 SoCs

On Mon, Jun 30, 2025 at 11:08:37PM +0200, Alexander Sverdlin wrote:
> Hi Inochi!
> 
> On Wed, 2025-06-11 at 16:02 +0800, Inochi Amaoto wrote:
> > Add device driver for the mux driver for Sophgo CV18XX/SG200X
> > series SoCs.
> > 
> > Signed-off-by: Inochi Amaoto <inochiama@...il.com>
> > ---
> >  drivers/net/mdio/Kconfig            |  10 +++
> >  drivers/net/mdio/Makefile           |   1 +
> >  drivers/net/mdio/mdio-mux-cv1800b.c | 119 ++++++++++++++++++++++++++++
> >  3 files changed, 130 insertions(+)
> >  create mode 100644 drivers/net/mdio/mdio-mux-cv1800b.c
> > 
> > diff --git a/drivers/net/mdio/Kconfig b/drivers/net/mdio/Kconfig
> > index 7db40aaa079d..fe553016b77d 100644
> > --- a/drivers/net/mdio/Kconfig
> > +++ b/drivers/net/mdio/Kconfig
> > @@ -278,5 +278,15 @@ config MDIO_BUS_MUX_MMIOREG
> >  
> >  	  Currently, only 8/16/32 bits registers are supported.
> >  
> > +config MDIO_BUS_MUX_SOPHGO_CV1800B
> > +	tristate "Sophgo CV1800 MDIO multiplexer driver"
> > +	depends on ARCH_SOPHGO || COMPILE_TEST
> > +	depends on OF_MDIO && HAS_IOMEM
> > +	select MDIO_BUS_MUX
> > +	default m if ARCH_SOPHGO
> > +	help
> > +	  This module provides a driver for the MDIO multiplexer/glue of
> > +	  the Sophgo CV1800 series SoC. The multiplexer connects either
> > +	  the external or the internal MDIO bus to the parent bus.
> >  
> >  endif
> > diff --git a/drivers/net/mdio/Makefile b/drivers/net/mdio/Makefile
> > index c23778e73890..a67be2abc343 100644
> > --- a/drivers/net/mdio/Makefile
> > +++ b/drivers/net/mdio/Makefile
> > @@ -33,3 +33,4 @@ obj-$(CONFIG_MDIO_BUS_MUX_MESON_G12A)	+= mdio-mux-meson-g12a.o
> >  obj-$(CONFIG_MDIO_BUS_MUX_MESON_GXL)	+= mdio-mux-meson-gxl.o
> >  obj-$(CONFIG_MDIO_BUS_MUX_MMIOREG) 	+= mdio-mux-mmioreg.o
> >  obj-$(CONFIG_MDIO_BUS_MUX_MULTIPLEXER) 	+= mdio-mux-multiplexer.o
> > +obj-$(CONFIG_MDIO_BUS_MUX_SOPHGO_CV1800B) += mdio-mux-cv1800b.o
> > diff --git a/drivers/net/mdio/mdio-mux-cv1800b.c b/drivers/net/mdio/mdio-mux-cv1800b.c
> > new file mode 100644
> > index 000000000000..6c69e83c3dcd
> > --- /dev/null
> > +++ b/drivers/net/mdio/mdio-mux-cv1800b.c
> > @@ -0,0 +1,119 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Sophgo CV1800 MDIO multiplexer driver
> > + *
> > + * Copyright (C) 2025 Inochi Amaoto <inochiama@...il.com>
> > + */
> > +
> > +#include <linux/bitfield.h>
> > +#include <linux/bits.h>
> > +#include <linux/delay.h>
> > +#include <linux/clk.h>
> > +#include <linux/io.h>
> > +#include <linux/mdio-mux.h>
> > +#include <linux/module.h>
> > +#include <linux/platform_device.h>
> > +
> > +#define EPHY_PAGE_SELECT		0x07c
> > +#define EPHY_CTRL			0x800
> > +#define EPHY_REG_SELECT			0x804
> > +
> > +#define EPHY_PAGE_SELECT_SRC		GENMASK(12, 8)
> > +
> > +#define EPHY_CTRL_ANALOG_SHUTDOWN	BIT(0)
> > +#define EPHY_CTRL_USE_EXTPHY		BIT(7)
> > +#define EPHY_CTRL_PHYMODE		BIT(8)
> > +#define EPHY_CTRL_PHYMODE_SMI_RMII	1
> > +#define EPHY_CTRL_EXTPHY_ID		GENMASK(15, 11)
> > +
> > +#define EPHY_REG_SELECT_MDIO		0
> > +#define EPHY_REG_SELECT_APB		1
> > +
> > +#define CV1800B_MDIO_INTERNAL_ID	1
> > +#define CV1800B_MDIO_EXTERNAL_ID	0
> > +
> > +struct cv1800b_mdio_mux {
> > +	void __iomem *regs;
> > +	void *mux_handle;
> > +};
> > +
> > +static int cv1800b_enable_mdio(struct cv1800b_mdio_mux *mdmux, bool internal_phy)
> > +{
> > +	u32 val;
> > +
> > +	val = readl(mdmux->regs + EPHY_CTRL);
> > +
> > +	if (internal_phy)
> > +		val &= ~EPHY_CTRL_USE_EXTPHY;
> > +	else
> > +		val |= EPHY_CTRL_USE_EXTPHY;
> > +
> > +	writel(val, mdmux->regs + EPHY_CTRL);
> > +
> > +	writel(EPHY_REG_SELECT_MDIO, mdmux->regs + EPHY_REG_SELECT);
> > +
> > +	return 0;
> > +}
> 
> Seems that it actually doesn't multiplex the buses? As seen on SG2000:
> 

A switch is also a multiplexer.

> # mdio mdio_mux-0.0
>  DEV      PHY-ID  LINK
> 0x00  0x00435649  up
> 0x01  0x00435649  up
> 0x02  0x00000000  down
> ...
> # mdio mdio_mux-0.1
>  DEV      PHY-ID  LINK
> 0x00  0x00435649  up
> 0x01  0x00435649  up
> ...
> 
> The single internal PHY appears on two addresses (0 and 1) and on both buses.

Only address 1 is right, all phy will respond address 0.
And you should not probe bus 1 when using internal bus,
it is not existed.

> Maybe it just switches the external MDIO master on/off?

Yes

> Seems that we need the documentation for this thing ;-)
> 

Please ask for the vendor.

> BTW, above LINK up is unfortunately without any cable attached...

I have repeat the led problem. After setting the right pinctrl,
It is always light and not blink. I guess there may be a internal
bug for it. I will ignore this problem as it is not the driver
issue.

Regards,
Inochi