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[PATCH net-next v3 1/4] net: mdio: Introduce a regmap-based mdio driver

Maxime Chevallier posted 4 patches 1 year, 3 months ago
There is a newer version of this series
[PATCH net-next v3 1/4] net: mdio: Introduce a regmap-based mdio driver
Posted by Maxime Chevallier 1 year, 3 months ago 
There exists several examples today of devices that embed an ethernet
PHY or PCS directly inside an SoC. In this situation, either the device
is controlled through a vendor-specific register set, or sometimes
exposes the standard 802.3 registers that are typically accessed over
MDIO.

As phylib and phylink are designed to use mdiodevices, this driver
allows creating a virtual MDIO bus, that translates mdiodev register
accesses to regmap accesses.

The reason we use regmap is because there are at least 3 such devices
known today, 2 of them are Altera TSE PCS's, memory-mapped, exposed
with a 4-byte stride in stmmac's dwmac-socfpga variant, and a 2-byte
stride in altera-tse. The other one (nxp,sja1110-base-tx-mdio) is
exposed over SPI.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
---
V2->V3 :
 - Introduce struct miod_regmap_priv for priv elements instead of plain
   reuse of the config struct
 - Use ~O instead of ~0UL
V1->V2 :
 - Use phy_mask to avoid unnecessary scanning, suggested by Andrew
 - Allow entirely disabling scanning, suggested by Vlad

 MAINTAINERS                         |  7 +++
 drivers/net/ethernet/altera/Kconfig |  2 +
 drivers/net/mdio/Kconfig            | 10 ++++
 drivers/net/mdio/Makefile           |  1 +
 drivers/net/mdio/mdio-regmap.c      | 93 +++++++++++++++++++++++++++++
 include/linux/mdio/mdio-regmap.h    | 24 ++++++++
 6 files changed, 137 insertions(+)
 create mode 100644 drivers/net/mdio/mdio-regmap.c
 create mode 100644 include/linux/mdio/mdio-regmap.h

diff --git a/MAINTAINERS b/MAINTAINERS
index c904dba1733b..f68269b39e09 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12835,6 +12835,13 @@ F:	Documentation/devicetree/bindings/net/ieee802154/mcr20a.txt
 F:	drivers/net/ieee802154/mcr20a.c
 F:	drivers/net/ieee802154/mcr20a.h
 
+MDIO REGMAP DRIVER
+M:	Maxime Chevallier <maxime.chevallier@bootlin.com>
+L:	netdev@vger.kernel.org
+S:	Maintained
+F:	drivers/net/mdio/mdio-regmap.c
+F:	include/linux/mdio/mdio-regmap.h
+
 MEASUREMENT COMPUTING CIO-DAC IIO DRIVER
 M:	William Breathitt Gray <william.gray@linaro.org>
 L:	linux-iio@vger.kernel.org
diff --git a/drivers/net/ethernet/altera/Kconfig b/drivers/net/ethernet/altera/Kconfig
index dd7fd41ccde5..0a7c0a217536 100644
--- a/drivers/net/ethernet/altera/Kconfig
+++ b/drivers/net/ethernet/altera/Kconfig
@@ -5,6 +5,8 @@ config ALTERA_TSE
 	select PHYLIB
 	select PHYLINK
 	select PCS_ALTERA_TSE
+	select MDIO_REGMAP
+	depends on REGMAP
 	help
 	  This driver supports the Altera Triple-Speed (TSE) Ethernet MAC.
 
diff --git a/drivers/net/mdio/Kconfig b/drivers/net/mdio/Kconfig
index 9ff2e6f22f3f..aef39c89cf44 100644
--- a/drivers/net/mdio/Kconfig
+++ b/drivers/net/mdio/Kconfig
@@ -185,6 +185,16 @@ config MDIO_IPQ8064
 	  This driver supports the MDIO interface found in the network
 	  interface units of the IPQ8064 SoC
 
+config MDIO_REGMAP
+	tristate
+	help
+	  This driver allows using MDIO devices that are not sitting on a
+	  regular MDIO bus, but still exposes the standard 802.3 register
+	  layout. It's regmap-based so that it can be used on integrated,
+	  memory-mapped PHYs, SPI PHYs and so on. A new virtual MDIO bus is
+	  created, and its read/write operations are mapped to the underlying
+	  regmap.
+
 config MDIO_THUNDER
 	tristate "ThunderX SOCs MDIO buses"
 	depends on 64BIT
diff --git a/drivers/net/mdio/Makefile b/drivers/net/mdio/Makefile
index 7d4cb4c11e4e..1015f0db4531 100644
--- a/drivers/net/mdio/Makefile
+++ b/drivers/net/mdio/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_MDIO_MOXART)		+= mdio-moxart.o
 obj-$(CONFIG_MDIO_MSCC_MIIM)		+= mdio-mscc-miim.o
 obj-$(CONFIG_MDIO_MVUSB)		+= mdio-mvusb.o
 obj-$(CONFIG_MDIO_OCTEON)		+= mdio-octeon.o
+obj-$(CONFIG_MDIO_REGMAP)		+= mdio-regmap.o
 obj-$(CONFIG_MDIO_SUN4I)		+= mdio-sun4i.o
 obj-$(CONFIG_MDIO_THUNDER)		+= mdio-thunder.o
 obj-$(CONFIG_MDIO_XGENE)		+= mdio-xgene.o
diff --git a/drivers/net/mdio/mdio-regmap.c b/drivers/net/mdio/mdio-regmap.c
new file mode 100644
index 000000000000..8a742a8d6387
--- /dev/null
+++ b/drivers/net/mdio/mdio-regmap.c
@@ -0,0 +1,93 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Driver for MMIO-Mapped MDIO devices. Some IPs expose internal PHYs or PCS
+ * within the MMIO-mapped area
+ *
+ * Copyright (C) 2023 Maxime Chevallier <maxime.chevallier@bootlin.com>
+ */
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/mdio.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_mdio.h>
+#include <linux/phy.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/mdio/mdio-regmap.h>
+
+#define DRV_NAME "mdio-regmap"
+
+struct mdio_regmap_priv {
+	struct regmap *regmap;
+	u8 valid_addr;
+};
+
+static int mdio_regmap_read_c22(struct mii_bus *bus, int addr, int regnum)
+{
+	struct mdio_regmap_priv *ctx = bus->priv;
+	unsigned int val;
+	int ret;
+
+	if (ctx->valid_addr != addr)
+		return -ENODEV;
+
+	ret = regmap_read(ctx->regmap, regnum, &val);
+	if (ret < 0)
+		return ret;
+
+	return val;
+}
+
+static int mdio_regmap_write_c22(struct mii_bus *bus, int addr, int regnum,
+				 u16 val)
+{
+	struct mdio_regmap_priv *ctx = bus->priv;
+
+	if (ctx->valid_addr != addr)
+		return -ENODEV;
+
+	return regmap_write(ctx->regmap, regnum, val);
+}
+
+struct mii_bus *devm_mdio_regmap_register(struct device *dev,
+					  const struct mdio_regmap_config *config)
+{
+	struct mdio_regmap_priv *mr;
+	struct mii_bus *mii;
+	int rc;
+
+	if (!config->parent)
+		return ERR_PTR(-EINVAL);
+
+	mii = devm_mdiobus_alloc_size(config->parent, sizeof(*mr));
+	if (!mii)
+		return ERR_PTR(-ENOMEM);
+
+	mr = mii->priv;
+	mr->regmap = config->regmap;
+	mr->valid_addr = config->valid_addr;
+
+	mii->name = DRV_NAME;
+	strscpy(mii->id, config->name, MII_BUS_ID_SIZE);
+	mii->parent = config->parent;
+	mii->read = mdio_regmap_read_c22;
+	mii->write = mdio_regmap_write_c22;
+
+	if (config->autoscan)
+		mii->phy_mask = ~BIT(config->valid_addr);
+	else
+		mii->phy_mask = ~0;
+
+	rc = devm_mdiobus_register(dev, mii);
+	if (rc) {
+		dev_err(config->parent, "Cannot register MDIO bus![%s] (%d)\n", mii->id, rc);
+		return ERR_PTR(rc);
+	}
+
+	return mii;
+}
+EXPORT_SYMBOL_GPL(devm_mdio_regmap_register);
+
+MODULE_DESCRIPTION("MDIO API over regmap");
+MODULE_AUTHOR("Maxime Chevallier <maxime.chevallier@bootlin.com>");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/mdio/mdio-regmap.h b/include/linux/mdio/mdio-regmap.h
new file mode 100644
index 000000000000..b8508f152552
--- /dev/null
+++ b/include/linux/mdio/mdio-regmap.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Driver for MMIO-Mapped MDIO devices. Some IPs expose internal PHYs or PCS
+ * within the MMIO-mapped area
+ *
+ * Copyright (C) 2023 Maxime Chevallier <maxime.chevallier@bootlin.com>
+ */
+#ifndef MDIO_REGMAP_H
+#define MDIO_REGMAP_H
+
+struct device;
+struct regmap;
+
+struct mdio_regmap_config {
+	struct device *parent;
+	struct regmap *regmap;
+	char name[MII_BUS_ID_SIZE];
+	u8 valid_addr;
+	bool autoscan;
+};
+
+struct mii_bus *devm_mdio_regmap_register(struct device *dev,
+					  const struct mdio_regmap_config *config);
+
+#endif
-- 
2.40.1
Re: [PATCH net-next v3 1/4] net: mdio: Introduce a regmap-based mdio driver
Posted by Vladimir Oltean 1 year, 3 months ago 
On Fri, May 26, 2023 at 09:42:49AM +0200, Maxime Chevallier wrote:
> There exists several examples today of devices that embed an ethernet
> PHY or PCS directly inside an SoC. In this situation, either the device
> is controlled through a vendor-specific register set, or sometimes
> exposes the standard 802.3 registers that are typically accessed over
> MDIO.
> 
> As phylib and phylink are designed to use mdiodevices, this driver
> allows creating a virtual MDIO bus, that translates mdiodev register
> accesses to regmap accesses.
> 
> The reason we use regmap is because there are at least 3 such devices
> known today, 2 of them are Altera TSE PCS's, memory-mapped, exposed
> with a 4-byte stride in stmmac's dwmac-socfpga variant, and a 2-byte
> stride in altera-tse. The other one (nxp,sja1110-base-tx-mdio) is
> exposed over SPI.
> 
> Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
> ---
> V2->V3 :
>  - Introduce struct miod_regmap_priv for priv elements instead of plain
>    reuse of the config struct
>  - Use ~O instead of ~0UL
> V1->V2 :
>  - Use phy_mask to avoid unnecessary scanning, suggested by Andrew
>  - Allow entirely disabling scanning, suggested by Vlad
> 
>  MAINTAINERS                         |  7 +++
>  drivers/net/ethernet/altera/Kconfig |  2 +
>  drivers/net/mdio/Kconfig            | 10 ++++
>  drivers/net/mdio/Makefile           |  1 +
>  drivers/net/mdio/mdio-regmap.c      | 93 +++++++++++++++++++++++++++++
>  include/linux/mdio/mdio-regmap.h    | 24 ++++++++
>  6 files changed, 137 insertions(+)
>  create mode 100644 drivers/net/mdio/mdio-regmap.c
>  create mode 100644 include/linux/mdio/mdio-regmap.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index c904dba1733b..f68269b39e09 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -12835,6 +12835,13 @@ F:	Documentation/devicetree/bindings/net/ieee802154/mcr20a.txt
>  F:	drivers/net/ieee802154/mcr20a.c
>  F:	drivers/net/ieee802154/mcr20a.h
>  
> +MDIO REGMAP DRIVER
> +M:	Maxime Chevallier <maxime.chevallier@bootlin.com>
> +L:	netdev@vger.kernel.org
> +S:	Maintained
> +F:	drivers/net/mdio/mdio-regmap.c
> +F:	include/linux/mdio/mdio-regmap.h
> +
>  MEASUREMENT COMPUTING CIO-DAC IIO DRIVER
>  M:	William Breathitt Gray <william.gray@linaro.org>
>  L:	linux-iio@vger.kernel.org
> diff --git a/drivers/net/ethernet/altera/Kconfig b/drivers/net/ethernet/altera/Kconfig
> index dd7fd41ccde5..0a7c0a217536 100644
> --- a/drivers/net/ethernet/altera/Kconfig
> +++ b/drivers/net/ethernet/altera/Kconfig
> @@ -5,6 +5,8 @@ config ALTERA_TSE
>  	select PHYLIB
>  	select PHYLINK
>  	select PCS_ALTERA_TSE
> +	select MDIO_REGMAP
> +	depends on REGMAP

I don't think this bit belongs in this patch.
Also: depends on REGMAP or select REGMAP?

>  	help
>  	  This driver supports the Altera Triple-Speed (TSE) Ethernet MAC.
>  
> diff --git a/drivers/net/mdio/Kconfig b/drivers/net/mdio/Kconfig
> index 9ff2e6f22f3f..aef39c89cf44 100644
> --- a/drivers/net/mdio/Kconfig
> +++ b/drivers/net/mdio/Kconfig
> @@ -185,6 +185,16 @@ config MDIO_IPQ8064
>  	  This driver supports the MDIO interface found in the network
>  	  interface units of the IPQ8064 SoC
>  
> +config MDIO_REGMAP
> +	tristate
> +	help
> +	  This driver allows using MDIO devices that are not sitting on a
> +	  regular MDIO bus, but still exposes the standard 802.3 register
> +	  layout. It's regmap-based so that it can be used on integrated,
> +	  memory-mapped PHYs, SPI PHYs and so on. A new virtual MDIO bus is
> +	  created, and its read/write operations are mapped to the underlying
> +	  regmap.

It would probably be helpful to state that those who select this option
should also explicitly select REGMAP.

> +
>  config MDIO_THUNDER
>  	tristate "ThunderX SOCs MDIO buses"
>  	depends on 64BIT
> diff --git a/drivers/net/mdio/Makefile b/drivers/net/mdio/Makefile
> index 7d4cb4c11e4e..1015f0db4531 100644
> --- a/drivers/net/mdio/Makefile
> +++ b/drivers/net/mdio/Makefile
> @@ -19,6 +19,7 @@ obj-$(CONFIG_MDIO_MOXART)		+= mdio-moxart.o
>  obj-$(CONFIG_MDIO_MSCC_MIIM)		+= mdio-mscc-miim.o
>  obj-$(CONFIG_MDIO_MVUSB)		+= mdio-mvusb.o
>  obj-$(CONFIG_MDIO_OCTEON)		+= mdio-octeon.o
> +obj-$(CONFIG_MDIO_REGMAP)		+= mdio-regmap.o
>  obj-$(CONFIG_MDIO_SUN4I)		+= mdio-sun4i.o
>  obj-$(CONFIG_MDIO_THUNDER)		+= mdio-thunder.o
>  obj-$(CONFIG_MDIO_XGENE)		+= mdio-xgene.o
> diff --git a/include/linux/mdio/mdio-regmap.h b/include/linux/mdio/mdio-regmap.h
> new file mode 100644
> index 000000000000..b8508f152552
> --- /dev/null
> +++ b/include/linux/mdio/mdio-regmap.h
> @@ -0,0 +1,24 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* Driver for MMIO-Mapped MDIO devices. Some IPs expose internal PHYs or PCS
> + * within the MMIO-mapped area
> + *
> + * Copyright (C) 2023 Maxime Chevallier <maxime.chevallier@bootlin.com>
> + */
> +#ifndef MDIO_REGMAP_H
> +#define MDIO_REGMAP_H
> +
> +struct device;
> +struct regmap;
> +
> +struct mdio_regmap_config {
> +	struct device *parent;
> +	struct regmap *regmap;
> +	char name[MII_BUS_ID_SIZE];

don't we need a header included for the MII_BUS_ID_SIZE macro?
An empty C file which includes just <linux/mdio/mdio-regmap.h> must
build without errors.

> +	u8 valid_addr;
> +	bool autoscan;
> +};
> +
> +struct mii_bus *devm_mdio_regmap_register(struct device *dev,
> +					  const struct mdio_regmap_config *config);
> +
> +#endif
> -- 
> 2.40.1
>
Re: [PATCH net-next v3 1/4] net: mdio: Introduce a regmap-based mdio driver
Posted by Maxime Chevallier 1 year, 3 months ago 
Hello Vlad,

On Fri, 26 May 2023 13:21:39 +0300
Vladimir Oltean <vladimir.oltean@nxp.com> wrote:

> >  M:	William Breathitt Gray <william.gray@linaro.org>
> >  L:	linux-iio@vger.kernel.org
> > diff --git a/drivers/net/ethernet/altera/Kconfig
> > b/drivers/net/ethernet/altera/Kconfig index
> > dd7fd41ccde5..0a7c0a217536 100644 ---
> > a/drivers/net/ethernet/altera/Kconfig +++
> > b/drivers/net/ethernet/altera/Kconfig @@ -5,6 +5,8 @@ config
> > ALTERA_TSE select PHYLIB
> >  	select PHYLINK
> >  	select PCS_ALTERA_TSE
> > +	select MDIO_REGMAP
> > +	depends on REGMAP  
> 
> I don't think this bit belongs in this patch.
> Also: depends on REGMAP or select REGMAP?

Ugh sorry about that... I'll address both the dependency and the wrong
patch splitting in next revision.

> >  	help
> >  	  This driver supports the Altera Triple-Speed (TSE)
> > Ethernet MAC. 
> > diff --git a/drivers/net/mdio/Kconfig b/drivers/net/mdio/Kconfig
> > index 9ff2e6f22f3f..aef39c89cf44 100644
> > --- a/drivers/net/mdio/Kconfig
> > +++ b/drivers/net/mdio/Kconfig
> > @@ -185,6 +185,16 @@ config MDIO_IPQ8064
> >  	  This driver supports the MDIO interface found in the
> > network interface units of the IPQ8064 SoC
> >  
> > +config MDIO_REGMAP
> > +	tristate
> > +	help
> > +	  This driver allows using MDIO devices that are not
> > sitting on a
> > +	  regular MDIO bus, but still exposes the standard 802.3
> > register
> > +	  layout. It's regmap-based so that it can be used on
> > integrated,
> > +	  memory-mapped PHYs, SPI PHYs and so on. A new virtual
> > MDIO bus is
> > +	  created, and its read/write operations are mapped to the
> > underlying
> > +	  regmap.  
> 
> It would probably be helpful to state that those who select this
> option should also explicitly select REGMAP.

You're right, I'll update this

> > +
> >  config MDIO_THUNDER
> >  	tristate "ThunderX SOCs MDIO buses"
> >  	depends on 64BIT
> > diff --git a/drivers/net/mdio/Makefile b/drivers/net/mdio/Makefile
> > index 7d4cb4c11e4e..1015f0db4531 100644
> > --- a/drivers/net/mdio/Makefile
> > +++ b/drivers/net/mdio/Makefile
> > @@ -19,6 +19,7 @@ obj-$(CONFIG_MDIO_MOXART)		+=
> > mdio-moxart.o obj-$(CONFIG_MDIO_MSCC_MIIM)		+=
> > mdio-mscc-miim.o obj-$(CONFIG_MDIO_MVUSB)		+=
> > mdio-mvusb.o obj-$(CONFIG_MDIO_OCTEON)		+=
> > mdio-octeon.o +obj-$(CONFIG_MDIO_REGMAP)		+=
> > mdio-regmap.o obj-$(CONFIG_MDIO_SUN4I)		+=
> > mdio-sun4i.o obj-$(CONFIG_MDIO_THUNDER)		+=
> > mdio-thunder.o obj-$(CONFIG_MDIO_XGENE)		+=
> > mdio-xgene.o diff --git a/include/linux/mdio/mdio-regmap.h
> > b/include/linux/mdio/mdio-regmap.h new file mode 100644
> > index 000000000000..b8508f152552
> > --- /dev/null
> > +++ b/include/linux/mdio/mdio-regmap.h
> > @@ -0,0 +1,24 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/* Driver for MMIO-Mapped MDIO devices. Some IPs expose internal
> > PHYs or PCS
> > + * within the MMIO-mapped area
> > + *
> > + * Copyright (C) 2023 Maxime Chevallier
> > <maxime.chevallier@bootlin.com>
> > + */
> > +#ifndef MDIO_REGMAP_H
> > +#define MDIO_REGMAP_H
> > +
> > +struct device;
> > +struct regmap;
> > +
> > +struct mdio_regmap_config {
> > +	struct device *parent;
> > +	struct regmap *regmap;
> > +	char name[MII_BUS_ID_SIZE];  
> 
> don't we need a header included for the MII_BUS_ID_SIZE macro?
> An empty C file which includes just <linux/mdio/mdio-regmap.h> must
> build without errors.

You're correct, I'll include the proper header.

Thanks,

Maxime

Patchew 2.1-devel-b67e4c2

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