Message-ID: <20211121174412.xi4dxw35qrfqyjjv@skbuf>
Date:   Sun, 21 Nov 2021 17:44:13 +0000
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     Colin Foster <colin.foster@...advantage.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Claudiu Manoil <claudiu.manoil@....com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        "UNGLinuxDriver@...rochip.com" <UNGLinuxDriver@...rochip.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>
Subject: Re: [PATCH v1 net-next 3/3] net: dsa: ocelot: felix: switch to
 mdio-mscc-miim driver for indirect mdio access

On Fri, Nov 19, 2021 at 01:39:18PM -0800, Colin Foster wrote:
> Switch to a shared MDIO access implementation now provided by
> drivers/net/mdio/mdio-mscc-miim.c
> 
> Signed-off-by: Colin Foster <colin.foster@...advantage.com>
> ---
>  drivers/net/dsa/ocelot/Kconfig           |   1 +
>  drivers/net/dsa/ocelot/Makefile          |   1 +
>  drivers/net/dsa/ocelot/felix_mdio.c      |  54 ++++++++++++
>  drivers/net/dsa/ocelot/felix_mdio.h      |  13 +++
>  drivers/net/dsa/ocelot/seville_vsc9953.c | 108 ++---------------------
>  drivers/net/mdio/mdio-mscc-miim.c        |  37 ++++++--
>  include/linux/mdio/mdio-mscc-miim.h      |  19 ++++
>  include/soc/mscc/ocelot.h                |   1 +
>  8 files changed, 125 insertions(+), 109 deletions(-)
>  create mode 100644 drivers/net/dsa/ocelot/felix_mdio.c
>  create mode 100644 drivers/net/dsa/ocelot/felix_mdio.h
>  create mode 100644 include/linux/mdio/mdio-mscc-miim.h
> 
> diff --git a/drivers/net/dsa/ocelot/Kconfig b/drivers/net/dsa/ocelot/Kconfig
> index 9948544ba1c4..220b0b027b55 100644
> --- a/drivers/net/dsa/ocelot/Kconfig
> +++ b/drivers/net/dsa/ocelot/Kconfig
> @@ -21,6 +21,7 @@ config NET_DSA_MSCC_SEVILLE
>  	depends on NET_VENDOR_MICROSEMI
>  	depends on HAS_IOMEM
>  	depends on PTP_1588_CLOCK_OPTIONAL
> +	select MDIO_MSCC_MIIM
>  	select MSCC_OCELOT_SWITCH_LIB
>  	select NET_DSA_TAG_OCELOT_8021Q
>  	select NET_DSA_TAG_OCELOT
> diff --git a/drivers/net/dsa/ocelot/Makefile b/drivers/net/dsa/ocelot/Makefile
> index f6dd131e7491..34b9b128efb8 100644
> --- a/drivers/net/dsa/ocelot/Makefile
> +++ b/drivers/net/dsa/ocelot/Makefile
> @@ -8,4 +8,5 @@ mscc_felix-objs := \
>  
>  mscc_seville-objs := \
>  	felix.o \
> +	felix_mdio.o \
>  	seville_vsc9953.o
> diff --git a/drivers/net/dsa/ocelot/felix_mdio.c b/drivers/net/dsa/ocelot/felix_mdio.c
> new file mode 100644
> index 000000000000..34375285756b
> --- /dev/null
> +++ b/drivers/net/dsa/ocelot/felix_mdio.c
> @@ -0,0 +1,54 @@
> +// SPDX-License-Identifier: (GPL-2.0 OR MIT)
> +/* Distributed Switch Architecture VSC9953 driver
> + * Copyright (C) 2020, Maxim Kochetkov <fido_max@...ox.ru>
> + * Copyright (C) 2021 Innovative Advantage
> + */
> +#include <linux/of_mdio.h>
> +#include <linux/types.h>
> +#include <soc/mscc/ocelot.h>
> +#include <linux/dsa/ocelot.h>
> +#include <linux/mdio/mdio-mscc-miim.h>
> +#include "felix.h"
> +#include "felix_mdio.h"
> +
> +int felix_of_mdio_register(struct ocelot *ocelot, struct device_node *np)
> +{
> +	struct felix *felix = ocelot_to_felix(ocelot);
> +	struct device *dev = ocelot->dev;
> +	int rc;
> +
> +	/* Needed in order to initialize the bus mutex lock */
> +	rc = of_mdiobus_register(felix->imdio, np);
> +	if (rc < 0) {
> +		dev_err(dev, "failed to register MDIO bus\n");
> +		felix->imdio = NULL;
> +	}
> +
> +	return rc;
> +}
> +
> +int felix_mdio_bus_alloc(struct ocelot *ocelot)
> +{
> +	struct felix *felix = ocelot_to_felix(ocelot);
> +	struct device *dev = ocelot->dev;
> +	struct mii_bus *bus;
> +	int err;
> +
> +	err = mscc_miim_setup(dev, &bus, ocelot->targets[GCB],
> +			      ocelot->map[GCB][GCB_MIIM_MII_STATUS & REG_MASK],
> +			      ocelot->targets[GCB],
> +			      ocelot->map[GCB][GCB_PHY_PHY_CFG & REG_MASK]);
> +
> +	if (!err)
> +		felix->imdio = bus;
> +
> +	return err;
> +}

I am a little doubtful of the value added by felix_mdio.c, since very
little is actually common. For example, the T1040 SoC has dpaa-eth
standalone ports (including the DSA master) and an embedded Seville
(VSC9953) switch. To access external PHYs connected to the switch, the
dpaa-eth MDIO bus is used (drivers/net/ethernet/freescale/xgmac_mdio.c).
The Microsemi MIIM MDIO controller from the Seville switch is used to
access only the NXP Lynx PCS, which is MDIO-mapped. That's why we put it
in felix->imdio (i == internal).

Whereas in your case, the Microsemi MIIM MDIO controller is used to
actually access the external PHYs. So it won't go in felix->imdio, since
it's not internal.

(yes, I know that NXP's integration of Vitesse switches is strange, but
it is what it is).

So unless I'm missing something, I guess you would be better off leaving
this code in Seville, and just duplicating minor portions of it (the
call to mscc_miim_setup) in your vsc7514 driver. What do you think?

> +
> +void felix_mdio_bus_free(struct ocelot *ocelot)
> +{
> +	struct felix *felix = ocelot_to_felix(ocelot);
> +
> +	if (felix->imdio)
> +		mdiobus_unregister(felix->imdio);
> +}
> diff --git a/drivers/net/dsa/ocelot/felix_mdio.h b/drivers/net/dsa/ocelot/felix_mdio.h
> new file mode 100644
> index 000000000000..93286f598c3b
> --- /dev/null
> +++ b/drivers/net/dsa/ocelot/felix_mdio.h
> @@ -0,0 +1,13 @@
> +/* SPDX-License-Identifier: GPL-2.0 OR MIT */
> +/* Shared code for indirect MDIO access for Felix drivers
> + *
> + * Author: Colin Foster <colin.foster@...advantage.com>
> + * Copyright (C) 2021 Innovative Advantage
> + */
> +#include <linux/of.h>
> +#include <linux/types.h>
> +#include <soc/mscc/ocelot.h>
> +
> +int felix_mdio_bus_alloc(struct ocelot *ocelot);
> +int felix_of_mdio_register(struct ocelot *ocelot, struct device_node *np);
> +void felix_mdio_bus_free(struct ocelot *ocelot);
> diff --git a/drivers/net/dsa/ocelot/seville_vsc9953.c b/drivers/net/dsa/ocelot/seville_vsc9953.c
> index db124922c374..dd7ae6a1d843 100644
> --- a/drivers/net/dsa/ocelot/seville_vsc9953.c
> +++ b/drivers/net/dsa/ocelot/seville_vsc9953.c
> @@ -10,15 +10,9 @@
>  #include <linux/pcs-lynx.h>
>  #include <linux/dsa/ocelot.h>
>  #include <linux/iopoll.h>
> -#include <linux/of_mdio.h>
>  #include "felix.h"
> +#include "felix_mdio.h"
>  
> -#define MSCC_MIIM_CMD_OPR_WRITE			BIT(1)
> -#define MSCC_MIIM_CMD_OPR_READ			BIT(2)
> -#define MSCC_MIIM_CMD_WRDATA_SHIFT		4
> -#define MSCC_MIIM_CMD_REGAD_SHIFT		20
> -#define MSCC_MIIM_CMD_PHYAD_SHIFT		25
> -#define MSCC_MIIM_CMD_VLD			BIT(31)
>  #define VSC9953_VCAP_POLICER_BASE		11
>  #define VSC9953_VCAP_POLICER_MAX		31
>  #define VSC9953_VCAP_POLICER_BASE2		120
> @@ -862,7 +856,6 @@ static struct vcap_props vsc9953_vcap_props[] = {
>  #define VSC9953_INIT_TIMEOUT			50000
>  #define VSC9953_GCB_RST_SLEEP			100
>  #define VSC9953_SYS_RAMINIT_SLEEP		80
> -#define VCS9953_MII_TIMEOUT			10000
>  
>  static int vsc9953_gcb_soft_rst_status(struct ocelot *ocelot)
>  {
> @@ -882,82 +875,6 @@ static int vsc9953_sys_ram_init_status(struct ocelot *ocelot)
>  	return val;
>  }
>  
> -static int vsc9953_gcb_miim_pending_status(struct ocelot *ocelot)
> -{
> -	int val;
> -
> -	ocelot_field_read(ocelot, GCB_MIIM_MII_STATUS_PENDING, &val);
> -
> -	return val;
> -}
> -
> -static int vsc9953_gcb_miim_busy_status(struct ocelot *ocelot)
> -{
> -	int val;
> -
> -	ocelot_field_read(ocelot, GCB_MIIM_MII_STATUS_BUSY, &val);
> -
> -	return val;
> -}
> -
> -static int vsc9953_mdio_write(struct mii_bus *bus, int phy_id, int regnum,
> -			      u16 value)
> -{
> -	struct ocelot *ocelot = bus->priv;
> -	int err, cmd, val;
> -
> -	/* Wait while MIIM controller becomes idle */
> -	err = readx_poll_timeout(vsc9953_gcb_miim_pending_status, ocelot,
> -				 val, !val, 10, VCS9953_MII_TIMEOUT);
> -	if (err) {
> -		dev_err(ocelot->dev, "MDIO write: pending timeout\n");
> -		goto out;
> -	}
> -
> -	cmd = MSCC_MIIM_CMD_VLD | (phy_id << MSCC_MIIM_CMD_PHYAD_SHIFT) |
> -	      (regnum << MSCC_MIIM_CMD_REGAD_SHIFT) |
> -	      (value << MSCC_MIIM_CMD_WRDATA_SHIFT) |
> -	      MSCC_MIIM_CMD_OPR_WRITE;
> -
> -	ocelot_write(ocelot, cmd, GCB_MIIM_MII_CMD);
> -
> -out:
> -	return err;
> -}
> -
> -static int vsc9953_mdio_read(struct mii_bus *bus, int phy_id, int regnum)
> -{
> -	struct ocelot *ocelot = bus->priv;
> -	int err, cmd, val;
> -
> -	/* Wait until MIIM controller becomes idle */
> -	err = readx_poll_timeout(vsc9953_gcb_miim_pending_status, ocelot,
> -				 val, !val, 10, VCS9953_MII_TIMEOUT);
> -	if (err) {
> -		dev_err(ocelot->dev, "MDIO read: pending timeout\n");
> -		goto out;
> -	}
> -
> -	/* Write the MIIM COMMAND register */
> -	cmd = MSCC_MIIM_CMD_VLD | (phy_id << MSCC_MIIM_CMD_PHYAD_SHIFT) |
> -	      (regnum << MSCC_MIIM_CMD_REGAD_SHIFT) | MSCC_MIIM_CMD_OPR_READ;
> -
> -	ocelot_write(ocelot, cmd, GCB_MIIM_MII_CMD);
> -
> -	/* Wait while read operation via the MIIM controller is in progress */
> -	err = readx_poll_timeout(vsc9953_gcb_miim_busy_status, ocelot,
> -				 val, !val, 10, VCS9953_MII_TIMEOUT);
> -	if (err) {
> -		dev_err(ocelot->dev, "MDIO read: busy timeout\n");
> -		goto out;
> -	}
> -
> -	val = ocelot_read(ocelot, GCB_MIIM_MII_DATA);
> -
> -	err = val & 0xFFFF;
> -out:
> -	return err;
> -}
>  
>  /* CORE_ENA is in SYS:SYSTEM:RESET_CFG
>   * MEM_INIT is in SYS:SYSTEM:RESET_CFG
> @@ -1089,7 +1006,6 @@ static int vsc9953_mdio_bus_alloc(struct ocelot *ocelot)
>  {
>  	struct felix *felix = ocelot_to_felix(ocelot);
>  	struct device *dev = ocelot->dev;
> -	struct mii_bus *bus;
>  	int port;
>  	int rc;
>  
> @@ -1101,26 +1017,18 @@ static int vsc9953_mdio_bus_alloc(struct ocelot *ocelot)
>  		return -ENOMEM;
>  	}
>  
> -	bus = devm_mdiobus_alloc(dev);
> -	if (!bus)
> -		return -ENOMEM;
> -
> -	bus->name = "VSC9953 internal MDIO bus";
> -	bus->read = vsc9953_mdio_read;
> -	bus->write = vsc9953_mdio_write;
> -	bus->parent = dev;
> -	bus->priv = ocelot;
> -	snprintf(bus->id, MII_BUS_ID_SIZE, "%s-imdio", dev_name(dev));
> +	rc = felix_mdio_bus_alloc(ocelot);
> +	if (rc < 0) {
> +		dev_err(dev, "failed to allocate MDIO bus\n");
> +		return rc;
> +	}
>  
> -	/* Needed in order to initialize the bus mutex lock */
> -	rc = of_mdiobus_register(bus, NULL);
> +	rc = felix_of_mdio_register(ocelot, NULL);
>  	if (rc < 0) {
>  		dev_err(dev, "failed to register MDIO bus\n");
>  		return rc;
>  	}
>  
> -	felix->imdio = bus;
> -
>  	for (port = 0; port < felix->info->num_ports; port++) {
>  		struct ocelot_port *ocelot_port = ocelot->ports[port];
>  		int addr = port + 4;
> @@ -1165,7 +1073,7 @@ static void vsc9953_mdio_bus_free(struct ocelot *ocelot)
>  		mdio_device_free(pcs->mdio);
>  		lynx_pcs_destroy(pcs);
>  	}
> -	mdiobus_unregister(felix->imdio);
> +	felix_mdio_bus_free(ocelot);
>  }
>  
>  static const struct felix_info seville_info_vsc9953 = {
> diff --git a/drivers/net/mdio/mdio-mscc-miim.c b/drivers/net/mdio/mdio-mscc-miim.c
> index f55ad20c28d5..cf3fa7a4459c 100644
> --- a/drivers/net/mdio/mdio-mscc-miim.c
> +++ b/drivers/net/mdio/mdio-mscc-miim.c
> @@ -10,6 +10,7 @@
>  #include <linux/io.h>
>  #include <linux/iopoll.h>
>  #include <linux/kernel.h>
> +#include <linux/mdio/mdio-mscc-miim.h>
>  #include <linux/module.h>
>  #include <linux/of_mdio.h>
>  #include <linux/phy.h>
> @@ -37,7 +38,9 @@
>  
>  struct mscc_miim_dev {
>  	struct regmap *regs;
> +	int mii_status_offset;
>  	struct regmap *phy_regs;
> +	int phy_reset_offset;
>  };
>  
>  /* When high resolution timers aren't built-in: we can't use usleep_range() as
> @@ -56,7 +59,8 @@ static int mscc_miim_status(struct mii_bus *bus)
>  	struct mscc_miim_dev *miim = bus->priv;
>  	int val, err;
>  
> -	err = regmap_read(miim->regs, MSCC_MIIM_REG_STATUS, &val);
> +	err = regmap_read(miim->regs,
> +			  MSCC_MIIM_REG_STATUS + miim->mii_status_offset, &val);
>  	if (err < 0)
>  		WARN_ONCE(1, "mscc miim status read error %d\n", err);
>  
> @@ -91,7 +95,9 @@ static int mscc_miim_read(struct mii_bus *bus, int mii_id, int regnum)
>  	if (ret)
>  		goto out;
>  
> -	err = regmap_write(miim->regs, MSCC_MIIM_REG_CMD, MSCC_MIIM_CMD_VLD |
> +	err = regmap_write(miim->regs,
> +			   MSCC_MIIM_REG_CMD + miim->mii_status_offset,
> +			   MSCC_MIIM_CMD_VLD |
>  			   (mii_id << MSCC_MIIM_CMD_PHYAD_SHIFT) |
>  			   (regnum << MSCC_MIIM_CMD_REGAD_SHIFT) |
>  			   MSCC_MIIM_CMD_OPR_READ);
> @@ -103,7 +109,8 @@ static int mscc_miim_read(struct mii_bus *bus, int mii_id, int regnum)
>  	if (ret)
>  		goto out;
>  
> -	err = regmap_read(miim->regs, MSCC_MIIM_REG_DATA, &val);
> +	err = regmap_read(miim->regs,
> +			  MSCC_MIIM_REG_DATA + miim->mii_status_offset, &val);
>  
>  	if (err < 0)
>  		WARN_ONCE(1, "mscc miim read data reg error %d\n", err);
> @@ -128,7 +135,9 @@ static int mscc_miim_write(struct mii_bus *bus, int mii_id,
>  	if (ret < 0)
>  		goto out;
>  
> -	err = regmap_write(miim->regs, MSCC_MIIM_REG_CMD, MSCC_MIIM_CMD_VLD |
> +	err = regmap_write(miim->regs,
> +			   MSCC_MIIM_REG_CMD + miim->mii_status_offset,
> +			   MSCC_MIIM_CMD_VLD |
>  			   (mii_id << MSCC_MIIM_CMD_PHYAD_SHIFT) |
>  			   (regnum << MSCC_MIIM_CMD_REGAD_SHIFT) |
>  			   (value << MSCC_MIIM_CMD_WRDATA_SHIFT) |
> @@ -143,14 +152,17 @@ static int mscc_miim_write(struct mii_bus *bus, int mii_id,
>  static int mscc_miim_reset(struct mii_bus *bus)
>  {
>  	struct mscc_miim_dev *miim = bus->priv;
> +	int offset = miim->phy_reset_offset;
>  	int err;
>  
>  	if (miim->phy_regs) {
> -		err = regmap_write(miim->phy_regs, MSCC_PHY_REG_PHY_CFG, 0);
> +		err = regmap_write(miim->phy_regs,
> +				   MSCC_PHY_REG_PHY_CFG + offset, 0);
>  		if (err < 0)
>  			WARN_ONCE(1, "mscc reset set error %d\n", err);
>  
> -		err = regmap_write(miim->phy_regs, MSCC_PHY_REG_PHY_CFG, 0x1ff);
> +		err = regmap_write(miim->phy_regs,
> +				   MSCC_PHY_REG_PHY_CFG + offset, 0x1ff);
>  		if (err < 0)
>  			WARN_ONCE(1, "mscc reset clear error %d\n", err);
>  
> @@ -166,10 +178,12 @@ static const struct regmap_config mscc_miim_regmap_config = {
>  	.reg_stride	= 4,
>  };
>  
> -static int mscc_miim_setup(struct device *dev, struct mii_bus *bus,
> -			   struct regmap *mii_regmap, struct regmap *phy_regmap)
> +int mscc_miim_setup(struct device *dev, struct mii_bus **pbus,
> +		    struct regmap *mii_regmap, int status_offset,
> +		    struct regmap *phy_regmap, int reset_offset)
>  {
>  	struct mscc_miim_dev *miim;
> +	struct mii_bus *bus;
>  
>  	bus = devm_mdiobus_alloc_size(dev, sizeof(*miim));
>  	if (!bus)
> @@ -185,10 +199,15 @@ static int mscc_miim_setup(struct device *dev, struct mii_bus *bus,
>  	miim = bus->priv;
>  
>  	miim->regs = mii_regmap;
> +	miim->mii_status_offset = status_offset;
>  	miim->phy_regs = phy_regmap;
> +	miim->phy_reset_offset = reset_offset;
> +
> +	*pbus = bus;
>  
>  	return 0;
>  }
> +EXPORT_SYMBOL(mscc_miim_setup);
>  
>  static int mscc_miim_probe(struct platform_device *pdev)
>  {
> @@ -225,7 +244,7 @@ static int mscc_miim_probe(struct platform_device *pdev)
>  		return PTR_ERR(dev->phy_regs);
>  	}
>  
> -	mscc_miim_setup(&pdev->dev, bus, mii_regmap, phy_regmap);
> +	mscc_miim_setup(&pdev->dev, &bus, mii_regmap, 0, phy_regmap, 0);
>  
>  	ret = of_mdiobus_register(bus, pdev->dev.of_node);
>  	if (ret < 0) {
> diff --git a/include/linux/mdio/mdio-mscc-miim.h b/include/linux/mdio/mdio-mscc-miim.h
> new file mode 100644
> index 000000000000..3ceab7b6ffc1
> --- /dev/null
> +++ b/include/linux/mdio/mdio-mscc-miim.h
> @@ -0,0 +1,19 @@
> +/* SPDX-License-Identifier: (GPL-2.0 OR MIT) */
> +/*
> + * Driver for the MDIO interface of Microsemi network switches.
> + *
> + * Author: Colin Foster <colin.foster@...advantage.com>
> + * Copyright (C) 2021 Innovative Advantage
> + */
> +#ifndef MDIO_MSCC_MIIM_H
> +#define MDIO_MSCC_MIIM_H
> +
> +#include <linux/device.h>
> +#include <linux/phy.h>
> +#include <linux/regmap.h>
> +
> +int mscc_miim_setup(struct device *device, struct mii_bus **bus,
> +		    struct regmap *mii_regmap, int status_offset,
> +		    struct regmap *phy_regmap, int reset_offset);
> +
> +#endif
> diff --git a/include/soc/mscc/ocelot.h b/include/soc/mscc/ocelot.h
> index 89d17629efe5..9d6fe8ce9dd1 100644
> --- a/include/soc/mscc/ocelot.h
> +++ b/include/soc/mscc/ocelot.h
> @@ -398,6 +398,7 @@ enum ocelot_reg {
>  	GCB_MIIM_MII_STATUS,
>  	GCB_MIIM_MII_CMD,
>  	GCB_MIIM_MII_DATA,
> +	GCB_PHY_PHY_CFG,
>  	DEV_CLOCK_CFG = DEV_GMII << TARGET_OFFSET,
>  	DEV_PORT_MISC,
>  	DEV_EVENTS,
> -- 
> 2.25.1
>

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