[PATCH net-next v3 3/4] enetc: Add ENETC PF level external MDIO support

[Claudiu Manoil <claudiu.manoil@nxp.com>]

Each ENETC PF has its own MDIO interface, the corresponding
MDIO registers are mapped in the ENETC's Port register block.
The current patch adds a driver for these PF level MDIO buses,
so that each PF can manage directly its own external link.

Signed-off-by: Alex Marginean <alexandru.marginean@nxp.com>
Signed-off-by: Claudiu Manoil <claudiu.manoil@nxp.com>
---
v2 - used readx_poll_timeout()
   - added mdio node child to the port node
   - added code comments, removed redundant err messages,
     minor code cleanup
v3 - replaced dev_err w/ dev_dbg for read() issues

 drivers/net/ethernet/freescale/enetc/Makefile     |   3 +-
 drivers/net/ethernet/freescale/enetc/enetc_mdio.c | 199 ++++++++++++++++++++++
 drivers/net/ethernet/freescale/enetc/enetc_pf.c   |  12 ++
 drivers/net/ethernet/freescale/enetc/enetc_pf.h   |   6 +
 4 files changed, 219 insertions(+), 1 deletion(-)
 create mode 100644 drivers/net/ethernet/freescale/enetc/enetc_mdio.c

diff --git a/drivers/net/ethernet/freescale/enetc/Makefile b/drivers/net/ethernet/freescale/enetc/Makefile
index 6976602..7139e41 100644
--- a/drivers/net/ethernet/freescale/enetc/Makefile
+++ b/drivers/net/ethernet/freescale/enetc/Makefile
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_FSL_ENETC) += fsl-enetc.o
-fsl-enetc-$(CONFIG_FSL_ENETC) += enetc.o enetc_cbdr.o enetc_ethtool.o
+fsl-enetc-$(CONFIG_FSL_ENETC) += enetc.o enetc_cbdr.o enetc_ethtool.o \
+				 enetc_mdio.o
 fsl-enetc-$(CONFIG_PCI_IOV) += enetc_msg.o
 fsl-enetc-objs := enetc_pf.o $(fsl-enetc-y)
 
diff --git a/drivers/net/ethernet/freescale/enetc/enetc_mdio.c b/drivers/net/ethernet/freescale/enetc/enetc_mdio.c
new file mode 100644
index 0000000..77b9cd1
--- /dev/null
+++ b/drivers/net/ethernet/freescale/enetc/enetc_mdio.c
@@ -0,0 +1,199 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
+/* Copyright 2019 NXP */
+
+#include <linux/mdio.h>
+#include <linux/of_mdio.h>
+#include <linux/iopoll.h>
+#include <linux/of.h>
+
+#include "enetc_pf.h"
+
+struct enetc_mdio_regs {
+	u32	mdio_cfg;	/* MDIO configuration and status */
+	u32	mdio_ctl;	/* MDIO control */
+	u32	mdio_data;	/* MDIO data */
+	u32	mdio_addr;	/* MDIO address */
+};
+
+#define bus_to_enetc_regs(bus)	(struct enetc_mdio_regs __iomem *)((bus)->priv)
+
+#define ENETC_MDIO_REG_OFFSET	0x1c00
+#define ENETC_MDC_DIV		258
+
+#define MDIO_CFG_CLKDIV(x)	((((x) >> 1) & 0xff) << 8)
+#define MDIO_CFG_BSY		BIT(0)
+#define MDIO_CFG_RD_ER		BIT(1)
+#define MDIO_CFG_ENC45		BIT(6)
+ /* external MDIO only - driven on neg MDC edge */
+#define MDIO_CFG_NEG		BIT(23)
+
+#define MDIO_CTL_DEV_ADDR(x)	((x) & 0x1f)
+#define MDIO_CTL_PORT_ADDR(x)	(((x) & 0x1f) << 5)
+#define MDIO_CTL_READ		BIT(15)
+#define MDIO_DATA(x)		((x) & 0xffff)
+
+#define TIMEOUT	1000
+static int enetc_mdio_wait_complete(struct enetc_mdio_regs __iomem *regs)
+{
+	u32 val;
+
+	return readx_poll_timeout(enetc_rd_reg, &regs->mdio_cfg, val,
+				  !(val & MDIO_CFG_BSY), 10, 10 * TIMEOUT);
+}
+
+static int enetc_mdio_write(struct mii_bus *bus, int phy_id, int regnum,
+			    u16 value)
+{
+	struct enetc_mdio_regs __iomem *regs = bus_to_enetc_regs(bus);
+	u32 mdio_ctl, mdio_cfg;
+	u16 dev_addr;
+	int ret;
+
+	mdio_cfg = MDIO_CFG_CLKDIV(ENETC_MDC_DIV) | MDIO_CFG_NEG;
+	if (regnum & MII_ADDR_C45) {
+		dev_addr = (regnum >> 16) & 0x1f;
+		mdio_cfg |= MDIO_CFG_ENC45;
+	} else {
+		/* clause 22 (ie 1G) */
+		dev_addr = regnum & 0x1f;
+		mdio_cfg &= ~MDIO_CFG_ENC45;
+	}
+
+	enetc_wr_reg(&regs->mdio_cfg, mdio_cfg);
+
+	ret = enetc_mdio_wait_complete(regs);
+	if (ret)
+		return ret;
+
+	/* set port and dev addr */
+	mdio_ctl = MDIO_CTL_PORT_ADDR(phy_id) | MDIO_CTL_DEV_ADDR(dev_addr);
+	enetc_wr_reg(&regs->mdio_ctl, mdio_ctl);
+
+	/* set the register address */
+	if (regnum & MII_ADDR_C45) {
+		enetc_wr_reg(&regs->mdio_addr, regnum & 0xffff);
+
+		ret = enetc_mdio_wait_complete(regs);
+		if (ret)
+			return ret;
+	}
+
+	/* write the value */
+	enetc_wr_reg(&regs->mdio_data, MDIO_DATA(value));
+
+	ret = enetc_mdio_wait_complete(regs);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int enetc_mdio_read(struct mii_bus *bus, int phy_id, int regnum)
+{
+	struct enetc_mdio_regs __iomem *regs = bus_to_enetc_regs(bus);
+	u32 mdio_ctl, mdio_cfg;
+	u16 dev_addr, value;
+	int ret;
+
+	mdio_cfg = MDIO_CFG_CLKDIV(ENETC_MDC_DIV) | MDIO_CFG_NEG;
+	if (regnum & MII_ADDR_C45) {
+		dev_addr = (regnum >> 16) & 0x1f;
+		mdio_cfg |= MDIO_CFG_ENC45;
+	} else {
+		dev_addr = regnum & 0x1f;
+		mdio_cfg &= ~MDIO_CFG_ENC45;
+	}
+
+	enetc_wr_reg(&regs->mdio_cfg, mdio_cfg);
+
+	ret = enetc_mdio_wait_complete(regs);
+	if (ret)
+		return ret;
+
+	/* set port and device addr */
+	mdio_ctl = MDIO_CTL_PORT_ADDR(phy_id) | MDIO_CTL_DEV_ADDR(dev_addr);
+	enetc_wr_reg(&regs->mdio_ctl, mdio_ctl);
+
+	/* set the register address */
+	if (regnum & MII_ADDR_C45) {
+		enetc_wr_reg(&regs->mdio_addr, regnum & 0xffff);
+
+		ret = enetc_mdio_wait_complete(regs);
+		if (ret)
+			return ret;
+	}
+
+	/* initiate the read */
+	enetc_wr_reg(&regs->mdio_ctl, mdio_ctl | MDIO_CTL_READ);
+
+	ret = enetc_mdio_wait_complete(regs);
+	if (ret)
+		return ret;
+
+	/* return all Fs if nothing was there */
+	if (enetc_rd_reg(&regs->mdio_cfg) & MDIO_CFG_RD_ER) {
+		dev_dbg(&bus->dev,
+			"Error while reading PHY%d reg at %d.%hhu\n",
+			phy_id, dev_addr, regnum);
+		return 0xffff;
+	}
+
+	value = enetc_rd_reg(&regs->mdio_data) & 0xffff;
+
+	return value;
+}
+
+int enetc_mdio_probe(struct enetc_pf *pf)
+{
+	struct device *dev = &pf->si->pdev->dev;
+	struct enetc_mdio_regs __iomem *regs;
+	struct device_node *np;
+	struct mii_bus *bus;
+	int ret;
+
+	bus = mdiobus_alloc_size(sizeof(regs));
+	if (!bus)
+		return -ENOMEM;
+
+	bus->name = "Freescale ENETC MDIO Bus";
+	bus->read = enetc_mdio_read;
+	bus->write = enetc_mdio_write;
+	bus->parent = dev;
+	snprintf(bus->id, MII_BUS_ID_SIZE, "%s", dev_name(dev));
+
+	/* store the enetc mdio base address for this bus */
+	regs = pf->si->hw.port + ENETC_MDIO_REG_OFFSET;
+	bus->priv = regs;
+
+	np = of_get_child_by_name(dev->of_node, "mdio");
+	if (!np) {
+		dev_err(dev, "MDIO node missing\n");
+		ret = -EINVAL;
+		goto err_registration;
+	}
+
+	ret = of_mdiobus_register(bus, np);
+	if (ret) {
+		of_node_put(np);
+		dev_err(dev, "cannot register MDIO bus\n");
+		goto err_registration;
+	}
+
+	of_node_put(np);
+	pf->mdio = bus;
+
+	return 0;
+
+err_registration:
+	mdiobus_free(bus);
+
+	return ret;
+}
+
+void enetc_mdio_remove(struct enetc_pf *pf)
+{
+	if (pf->mdio) {
+		mdiobus_unregister(pf->mdio);
+		mdiobus_free(pf->mdio);
+	}
+}
diff --git a/drivers/net/ethernet/freescale/enetc/enetc_pf.c b/drivers/net/ethernet/freescale/enetc/enetc_pf.c
index 7d28f5e..15876a6 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc_pf.c
+++ b/drivers/net/ethernet/freescale/enetc/enetc_pf.c
@@ -746,6 +746,7 @@ static void enetc_pf_netdev_setup(struct enetc_si *si, struct net_device *ndev,
 
 static int enetc_of_get_phy(struct enetc_ndev_priv *priv)
 {
+	struct enetc_pf *pf = enetc_si_priv(priv->si);
 	struct device_node *np = priv->dev->of_node;
 	int err;
 
@@ -770,12 +771,22 @@ static int enetc_of_get_phy(struct enetc_ndev_priv *priv)
 		priv->phy_node = of_node_get(np);
 	}
 
+	if (!of_phy_is_fixed_link(np)) {
+		err = enetc_mdio_probe(pf);
+		if (err) {
+			of_node_put(priv->phy_node);
+			return err;
+		}
+	}
+
 	priv->if_mode = of_get_phy_mode(np);
 	if (priv->if_mode < 0) {
 		dev_err(priv->dev, "missing phy type\n");
 		of_node_put(priv->phy_node);
 		if (of_phy_is_fixed_link(np))
 			of_phy_deregister_fixed_link(np);
+		else
+			enetc_mdio_remove(pf);
 
 		return -EINVAL;
 	}
@@ -898,6 +909,7 @@ static void enetc_pf_remove(struct pci_dev *pdev)
 
 	unregister_netdev(si->ndev);
 
+	enetc_mdio_remove(pf);
 	enetc_of_put_phy(priv);
 
 	enetc_free_msix(priv);
diff --git a/drivers/net/ethernet/freescale/enetc/enetc_pf.h b/drivers/net/ethernet/freescale/enetc/enetc_pf.h
index 2061ae5..10dd1b5 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc_pf.h
+++ b/drivers/net/ethernet/freescale/enetc/enetc_pf.h
@@ -42,8 +42,14 @@ struct enetc_pf {
 	char vlan_promisc_simap; /* bitmap of SIs in VLAN promisc mode */
 	DECLARE_BITMAP(vlan_ht_filter, ENETC_VLAN_HT_SIZE);
 	DECLARE_BITMAP(active_vlans, VLAN_N_VID);
+
+	struct mii_bus *mdio; /* saved for cleanup */
 };
 
 int enetc_msg_psi_init(struct enetc_pf *pf);
 void enetc_msg_psi_free(struct enetc_pf *pf);
 void enetc_msg_handle_rxmsg(struct enetc_pf *pf, int mbox_id, u16 *status);
+
+/* MDIO */
+int enetc_mdio_probe(struct enetc_pf *pf);
+void enetc_mdio_remove(struct enetc_pf *pf);
-- 
2.7.4