This patch adds support in phylib to read/write PLCA configuration for
Ethernet PHYs that support the OPEN Alliance "10BASE-T1S PLCA
Management Registers" specifications. These can be found at
https://www.opensig.org/about/specifications/

Signed-off-by: Piergiorgio Beruto <piergiorgio.beruto@gmail.com>
---
 MAINTAINERS                          |   1 +
 drivers/net/phy/mdio-open-alliance.h |  46 +++++++
 drivers/net/phy/phy-c45.c            | 183 +++++++++++++++++++++++++++
 include/linux/phy.h                  |   6 +
 4 files changed, 236 insertions(+)
 create mode 100644 drivers/net/phy/mdio-open-alliance.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 8faa15c360e3..4356382ad57c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16617,6 +16617,7 @@ PLCA RECONCILIATION SUBLAYER (IEEE802.3 Clause 148)
 M:	Piergiorgio Beruto <piergiorgio.beruto@gmail.com>
 L:	netdev@vger.kernel.org
 S:	Maintained
+F:	drivers/net/phy/mdio-open-alliance.h
 F:	net/ethtool/plca.c
 
 PLDMFW LIBRARY
diff --git a/drivers/net/phy/mdio-open-alliance.h b/drivers/net/phy/mdio-open-alliance.h
new file mode 100644
index 000000000000..931e14660d75
--- /dev/null
+++ b/drivers/net/phy/mdio-open-alliance.h
@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * mdio-open-alliance.h - definition of OPEN Alliance SIG standard registers
+ */
+
+#ifndef __MDIO_OPEN_ALLIANCE__
+#define __MDIO_OPEN_ALLIANCE__
+
+#include <linux/mdio.h>
+
+/* NOTE: all OATC14 registers are located in MDIO_MMD_VEND2 */
+
+/* Open Alliance TC14 (10BASE-T1S) registers */
+#define MDIO_OATC14_PLCA_IDVER	0xca00  /* PLCA ID and version */
+#define MDIO_OATC14_PLCA_CTRL0	0xca01	/* PLCA Control register 0 */
+#define MDIO_OATC14_PLCA_CTRL1	0xca02	/* PLCA Control register 1 */
+#define MDIO_OATC14_PLCA_STATUS	0xca03	/* PLCA Status register */
+#define MDIO_OATC14_PLCA_TOTMR	0xca04	/* PLCA TO Timer register */
+#define MDIO_OATC14_PLCA_BURST	0xca05	/* PLCA BURST mode register */
+
+/* Open Alliance TC14 PLCA IDVER register */
+#define MDIO_OATC14_PLCA_IDM	0xff00	/* PLCA MAP ID */
+#define MDIO_OATC14_PLCA_VER	0x00ff	/* PLCA MAP version */
+
+/* Open Alliance TC14 PLCA CTRL0 register */
+#define MDIO_OATC14_PLCA_EN	BIT(15) /* PLCA enable */
+#define MDIO_OATC14_PLCA_RST	BIT(14) /* PLCA reset */
+
+/* Open Alliance TC14 PLCA CTRL1 register */
+#define MDIO_OATC14_PLCA_NCNT	0xff00	/* PLCA node count */
+#define MDIO_OATC14_PLCA_ID	0x00ff	/* PLCA local node ID */
+
+/* Open Alliance TC14 PLCA STATUS register */
+#define MDIO_OATC14_PLCA_PST	BIT(15)	/* PLCA status indication */
+
+/* Open Alliance TC14 PLCA TOTMR register */
+#define MDIO_OATC14_PLCA_TOT	0x00ff
+
+/* Open Alliance TC14 PLCA BURST register */
+#define MDIO_OATC14_PLCA_MAXBC	0xff00
+#define MDIO_OATC14_PLCA_BTMR	0x00ff
+
+/* Version Identifiers */
+#define OATC14_IDM		0x0a00
+
+#endif /* __MDIO_OPEN_ALLIANCE__ */
diff --git a/drivers/net/phy/phy-c45.c b/drivers/net/phy/phy-c45.c
index a87a4b3ffce4..508edd1f17d7 100644
--- a/drivers/net/phy/phy-c45.c
+++ b/drivers/net/phy/phy-c45.c
@@ -8,6 +8,8 @@
 #include <linux/mii.h>
 #include <linux/phy.h>
 
+#include "mdio-open-alliance.h"
+
 /**
  * genphy_c45_baset1_able - checks if the PMA has BASE-T1 extended abilities
  * @phydev: target phy_device struct
@@ -931,6 +933,187 @@ int genphy_c45_fast_retrain(struct phy_device *phydev, bool enable)
 }
 EXPORT_SYMBOL_GPL(genphy_c45_fast_retrain);
 
+/**
+ * genphy_c45_plca_get_cfg - get PLCA configuration from standard registers
+ * @phydev: target phy_device struct
+ * @plca_cfg: output structure to store the PLCA configuration
+ *
+ * Description: if the PHY complies to the Open Alliance TC14 10BASE-T1S PLCA
+ *   Management Registers specifications, this function can be used to retrieve
+ *   the current PLCA configuration from the standard registers in MMD 31.
+ */
+int genphy_c45_plca_get_cfg(struct phy_device *phydev,
+			    struct phy_plca_cfg *plca_cfg)
+{
+	int ret;
+
+	ret = phy_read_mmd(phydev, MDIO_MMD_VEND2, MDIO_OATC14_PLCA_IDVER);
+	if (ret < 0)
+		return ret;
+
+	if ((ret & MDIO_OATC14_PLCA_IDM) != OATC14_IDM)
+		return -ENODEV;
+
+	plca_cfg->version = ret & ~MDIO_OATC14_PLCA_IDM;
+
+	ret = phy_read_mmd(phydev, MDIO_MMD_VEND2, MDIO_OATC14_PLCA_CTRL0);
+	if (ret < 0)
+		return ret;
+
+	plca_cfg->enabled = !!(ret & MDIO_OATC14_PLCA_EN);
+
+	ret = phy_read_mmd(phydev, MDIO_MMD_VEND2, MDIO_OATC14_PLCA_CTRL1);
+	if (ret < 0)
+		return ret;
+
+	plca_cfg->node_cnt = (ret & MDIO_OATC14_PLCA_NCNT) >> 8;
+	plca_cfg->node_id = (ret & MDIO_OATC14_PLCA_ID);
+
+	ret = phy_read_mmd(phydev, MDIO_MMD_VEND2, MDIO_OATC14_PLCA_TOTMR);
+	if (ret < 0)
+		return ret;
+
+	plca_cfg->to_tmr = ret & MDIO_OATC14_PLCA_TOT;
+
+	ret = phy_read_mmd(phydev, MDIO_MMD_VEND2, MDIO_OATC14_PLCA_BURST);
+	if (ret < 0)
+		return ret;
+
+	plca_cfg->burst_cnt = (ret & MDIO_OATC14_PLCA_MAXBC) >> 8;
+	plca_cfg->burst_tmr = (ret & MDIO_OATC14_PLCA_BTMR);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(genphy_c45_plca_get_cfg);
+
+/**
+ * genphy_c45_plca_set_cfg - set PLCA configuration using standard registers
+ * @phydev: target phy_device struct
+ * @plca_cfg: structure containing the PLCA configuration. Fields set to -1 are
+ * not to be changed.
+ *
+ * Description: if the PHY complies to the Open Alliance TC14 10BASE-T1S PLCA
+ *   Management Registers specifications, this function can be used to modify
+ *   the PLCA configuration using the standard registers in MMD 31.
+ */
+int genphy_c45_plca_set_cfg(struct phy_device *phydev,
+			    const struct phy_plca_cfg *plca_cfg)
+{
+	int ret;
+	u16 val;
+
+	// PLCA IDVER is read-only
+	if (plca_cfg->version >= 0)
+		return -EINVAL;
+
+	// first of all, disable PLCA if required
+	if (plca_cfg->enabled == 0) {
+		ret = phy_clear_bits_mmd(phydev, MDIO_MMD_VEND2,
+					 MDIO_OATC14_PLCA_CTRL0,
+					 MDIO_OATC14_PLCA_EN);
+
+		if (ret < 0)
+			return ret;
+	}
+
+	if (plca_cfg->node_cnt >= 0 || plca_cfg->node_id >= 0) {
+		if (plca_cfg->node_cnt < 0 || plca_cfg->node_id < 0) {
+			ret = phy_read_mmd(phydev, MDIO_MMD_VEND2,
+					   MDIO_OATC14_PLCA_CTRL1);
+
+			if (ret < 0)
+				return ret;
+
+			val = ret;
+		}
+
+		if (plca_cfg->node_cnt >= 0)
+			val = (val & ~MDIO_OATC14_PLCA_NCNT) |
+			      (plca_cfg->node_cnt << 8);
+
+		if (plca_cfg->node_id >= 0)
+			val = (val & ~MDIO_OATC14_PLCA_ID) |
+			      (plca_cfg->node_id);
+
+		ret = phy_write_mmd(phydev, MDIO_MMD_VEND2,
+				    MDIO_OATC14_PLCA_CTRL1, val);
+
+		if (ret < 0)
+			return ret;
+	}
+
+	if (plca_cfg->to_tmr >= 0) {
+		ret = phy_write_mmd(phydev, MDIO_MMD_VEND2,
+				    MDIO_OATC14_PLCA_TOTMR,
+				    plca_cfg->to_tmr);
+
+		if (ret < 0)
+			return ret;
+	}
+
+	if (plca_cfg->burst_cnt >= 0 || plca_cfg->burst_tmr >= 0) {
+		if (plca_cfg->burst_cnt < 0 || plca_cfg->burst_tmr < 0) {
+			ret = phy_read_mmd(phydev, MDIO_MMD_VEND2,
+					   MDIO_OATC14_PLCA_BURST);
+
+			if (ret < 0)
+				return ret;
+
+			val = ret;
+		}
+
+		if (plca_cfg->burst_cnt >= 0)
+			val = (val & ~MDIO_OATC14_PLCA_MAXBC) |
+			      (plca_cfg->burst_cnt << 8);
+
+		if (plca_cfg->burst_tmr >= 0)
+			val = (val & ~MDIO_OATC14_PLCA_BTMR) |
+			      (plca_cfg->burst_tmr);
+
+		ret = phy_write_mmd(phydev, MDIO_MMD_VEND2,
+				    MDIO_OATC14_PLCA_BURST, val);
+
+		if (ret < 0)
+			return ret;
+	}
+
+	// if we need to enable PLCA, do it at the end
+	if (plca_cfg->enabled > 0) {
+		ret = phy_set_bits_mmd(phydev, MDIO_MMD_VEND2,
+				       MDIO_OATC14_PLCA_CTRL0,
+				       MDIO_OATC14_PLCA_EN);
+
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(genphy_c45_plca_set_cfg);
+
+/**
+ * genphy_c45_plca_get_status - get PLCA status from standard registers
+ * @phydev: target phy_device struct
+ * @plca_st: output structure to store the PLCA status
+ *
+ * Description: if the PHY complies to the Open Alliance TC14 10BASE-T1S PLCA
+ *   Management Registers specifications, this function can be used to retrieve
+ *   the current PLCA status information from the standard registers in MMD 31.
+ */
+int genphy_c45_plca_get_status(struct phy_device *phydev,
+			       struct phy_plca_status *plca_st)
+{
+	int ret;
+
+	ret = phy_read_mmd(phydev, MDIO_MMD_VEND2, MDIO_OATC14_PLCA_STATUS);
+	if (ret < 0)
+		return ret;
+
+	plca_st->pst = !!(ret & MDIO_OATC14_PLCA_PST);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(genphy_c45_plca_get_status);
+
 struct phy_driver genphy_c45_driver = {
 	.phy_id         = 0xffffffff,
 	.phy_id_mask    = 0xffffffff,
diff --git a/include/linux/phy.h b/include/linux/phy.h
index bcaf1dfd0687..23aa23cde940 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -1748,6 +1748,12 @@ int genphy_c45_loopback(struct phy_device *phydev, bool enable);
 int genphy_c45_pma_resume(struct phy_device *phydev);
 int genphy_c45_pma_suspend(struct phy_device *phydev);
 int genphy_c45_fast_retrain(struct phy_device *phydev, bool enable);
+int genphy_c45_plca_get_cfg(struct phy_device *phydev,
+			    struct phy_plca_cfg *plca_cfg);
+int genphy_c45_plca_set_cfg(struct phy_device *phydev,
+			    const struct phy_plca_cfg *plca_cfg);
+int genphy_c45_plca_get_status(struct phy_device *phydev,
+			       struct phy_plca_status *plca_st);
 
 /* Generic C45 PHY driver */
 extern struct phy_driver genphy_c45_driver;
-- 
2.37.4

> +/**
> + * genphy_c45_plca_set_cfg - set PLCA configuration using standard registers
> + * @phydev: target phy_device struct
> + * @plca_cfg: structure containing the PLCA configuration. Fields set to -1 are
> + * not to be changed.
> + *
> + * Description: if the PHY complies to the Open Alliance TC14 10BASE-T1S PLCA
> + *   Management Registers specifications, this function can be used to modify
> + *   the PLCA configuration using the standard registers in MMD 31.
> + */
> +int genphy_c45_plca_set_cfg(struct phy_device *phydev,
> +			    const struct phy_plca_cfg *plca_cfg)
> +{
> +	int ret;
> +	u16 val;
> +
> +	// PLCA IDVER is read-only
> +	if (plca_cfg->version >= 0)
> +		return -EINVAL;
> +
> +	// first of all, disable PLCA if required
> +	if (plca_cfg->enabled == 0) {
> +		ret = phy_clear_bits_mmd(phydev, MDIO_MMD_VEND2,
> +					 MDIO_OATC14_PLCA_CTRL0,
> +					 MDIO_OATC14_PLCA_EN);
> +
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	if (plca_cfg->node_cnt >= 0 || plca_cfg->node_id >= 0) {
> +		if (plca_cfg->node_cnt < 0 || plca_cfg->node_id < 0) {

I think it would be good to add some comments since this code is not
immediately obvious to me. I had to think about it for a while.

> +	if (plca_cfg->burst_cnt >= 0 || plca_cfg->burst_tmr >= 0) {
> +		if (plca_cfg->burst_cnt < 0 || plca_cfg->burst_tmr < 0) {
> +			ret = phy_read_mmd(phydev, MDIO_MMD_VEND2,
> +					   MDIO_OATC14_PLCA_BURST);
> +

This follows the same patterns, so maybe comments here as well?

With that, you can add my Reviewed-by.

     Andrew

On Sat, Jan 07, 2023 at 07:07:52PM +0100, Andrew Lunn wrote:
> > +/**
> > + * genphy_c45_plca_set_cfg - set PLCA configuration using standard registers
> > + * @phydev: target phy_device struct
> > + * @plca_cfg: structure containing the PLCA configuration. Fields set to -1 are
> > + * not to be changed.
> > + *
> > + * Description: if the PHY complies to the Open Alliance TC14 10BASE-T1S PLCA
> > + *   Management Registers specifications, this function can be used to modify
> > + *   the PLCA configuration using the standard registers in MMD 31.
> > + */
> > +int genphy_c45_plca_set_cfg(struct phy_device *phydev,
> > +			    const struct phy_plca_cfg *plca_cfg)
> > +{
> > +	int ret;
> > +	u16 val;
> > +
> > +	// PLCA IDVER is read-only
> > +	if (plca_cfg->version >= 0)
> > +		return -EINVAL;
> > +
> > +	// first of all, disable PLCA if required
> > +	if (plca_cfg->enabled == 0) {
> > +		ret = phy_clear_bits_mmd(phydev, MDIO_MMD_VEND2,
> > +					 MDIO_OATC14_PLCA_CTRL0,
> > +					 MDIO_OATC14_PLCA_EN);
> > +
> > +		if (ret < 0)
> > +			return ret;
> > +	}
> > +
> > +	if (plca_cfg->node_cnt >= 0 || plca_cfg->node_id >= 0) {
> > +		if (plca_cfg->node_cnt < 0 || plca_cfg->node_id < 0) {
> 
> I think it would be good to add some comments since this code is not
> immediately obvious to me. I had to think about it for a while.
Yes, I realize it is not very intuitive at furst glance :-)
I have added a comment explaining that we need to read back the register
to perform merge/pure of the configuration IFF we need to set one among
node ID / node count but not both.

> 
> > +	if (plca_cfg->burst_cnt >= 0 || plca_cfg->burst_tmr >= 0) {
> > +		if (plca_cfg->burst_cnt < 0 || plca_cfg->burst_tmr < 0) {
> > +			ret = phy_read_mmd(phydev, MDIO_MMD_VEND2,
> > +					   MDIO_OATC14_PLCA_BURST);
> > +
> 
> This follows the same patterns, so maybe comments here as well?
Yup, added the same comment.
> 
> With that, you can add my Reviewed-by.
Thanks!
> 
>      Andrew