drivers: net: add Layerscape mEMAC MDIO driver

Add a driver for the MDIO interface integrated in the mEMAC (Multi-rate
Ethernet Media Access Controller) and the Fman 10G Ethernet MACs.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>

drivers/net/Kconfig

@@ -640,4 +640,11 @@ config MVMDIO
 
 	  This driver is used by the MVPP2 and MVNETA drivers.
 
+config FSL_LS_MDIO
+	bool "NXP Layerscape MDIO interface support"
+	depends on DM_MDIO
+	help
+	  This driver supports the MDIO bus found on the Fman 10G Ethernet MACs and
+	  on the mEMAC (which supports both Clauses 22 and 45).
+
 endif # NETDEVICES

drivers/net/Makefile

@@ -83,3 +83,4 @@ obj-y += mscc_eswitch/
 obj-$(CONFIG_HIGMACV300_ETH) += higmacv300.o
 obj-$(CONFIG_MDIO_SANDBOX) += mdio_sandbox.o
 obj-$(CONFIG_FSL_ENETC) += fsl_enetc.o fsl_enetc_mdio.o
+obj-$(CONFIG_FSL_LS_MDIO) += fsl_ls_mdio.o

drivers/net/fsl_ls_mdio.c

@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2020 NXP
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <miiphy.h>
+#include <asm/io.h>
+#include <fsl_memac.h>
+
+#ifdef CONFIG_SYS_MEMAC_LITTLE_ENDIAN
+#define memac_out_32(a, v)	out_le32(a, v)
+#define memac_clrbits_32(a, v)	clrbits_le32(a, v)
+#define memac_setbits_32(a, v)	setbits_le32(a, v)
+#else
+#define memac_out_32(a, v)	out_be32(a, v)
+#define memac_clrbits_32(a, v)	clrbits_be32(a, v)
+#define memac_setbits_32(a, v)	setbits_be32(a, v)
+#endif
+
+static u32 memac_in_32(u32 *reg)
+{
+#ifdef CONFIG_SYS_MEMAC_LITTLE_ENDIAN
+	return in_le32(reg);
+#else
+	return in_be32(reg);
+#endif
+}
+
+struct fsl_ls_mdio_priv {
+	void *regs_base;
+};
+
+static u32 fsl_ls_mdio_setup_operation(struct udevice *dev, int addr, int devad,
+				       int reg)
+{
+	struct fsl_ls_mdio_priv *priv = dev_get_priv(dev);
+	struct memac_mdio_controller *regs;
+	u32 mdio_ctl;
+	u32 c45 = 1;
+
+	regs = (struct memac_mdio_controller *)(priv->regs_base);
+	if (devad == MDIO_DEVAD_NONE) {
+		c45 = 0; /* clause 22 */
+		devad = reg & 0x1f;
+		memac_clrbits_32(&regs->mdio_stat, MDIO_STAT_ENC);
+	} else {
+		memac_setbits_32(&regs->mdio_stat, MDIO_STAT_ENC);
+	}
+
+	/* Wait till the bus is free */
+	while ((memac_in_32(&regs->mdio_stat)) & MDIO_STAT_BSY)
+		;
+
+	/* Set the Port and Device Addrs */
+	mdio_ctl = MDIO_CTL_PORT_ADDR(addr) | MDIO_CTL_DEV_ADDR(devad);
+	memac_out_32(&regs->mdio_ctl, mdio_ctl);
+
+	/* Set the register address */
+	if (c45)
+		memac_out_32(&regs->mdio_addr, reg & 0xffff);
+
+	/* Wait till the bus is free */
+	while ((memac_in_32(&regs->mdio_stat)) & MDIO_STAT_BSY)
+		;
+
+	return mdio_ctl;
+}
+
+static int dm_fsl_ls_mdio_read(struct udevice *dev, int addr,
+			       int devad, int reg)
+{
+	struct fsl_ls_mdio_priv *priv = dev_get_priv(dev);
+	struct memac_mdio_controller *regs;
+	u32 mdio_ctl;
+
+	regs = (struct memac_mdio_controller *)(priv->regs_base);
+	mdio_ctl = fsl_ls_mdio_setup_operation(dev, addr, devad, reg);
+
+	/* Initiate the read */
+	mdio_ctl |= MDIO_CTL_READ;
+	memac_out_32(&regs->mdio_ctl, mdio_ctl);
+
+	/* Wait till the MDIO write is complete */
+	while ((memac_in_32(&regs->mdio_data)) & MDIO_DATA_BSY)
+		;
+
+	/* Return all Fs if nothing was there */
+	if (memac_in_32(&regs->mdio_stat) & MDIO_STAT_RD_ER)
+		return 0xffff;
+
+	return memac_in_32(&regs->mdio_data) & 0xffff;
+}
+
+static int dm_fsl_ls_mdio_write(struct udevice *dev, int addr, int devad,
+				int reg, u16 val)
+{
+	struct fsl_ls_mdio_priv *priv = dev_get_priv(dev);
+	struct memac_mdio_controller *regs;
+
+	regs = (struct memac_mdio_controller *)(priv->regs_base);
+	fsl_ls_mdio_setup_operation(dev, addr, devad, reg);
+
+	/* Write the value to the register */
+	memac_out_32(&regs->mdio_data, MDIO_DATA(val));
+
+	/* Wait till the MDIO write is complete */
+	while ((memac_in_32(&regs->mdio_data)) & MDIO_DATA_BSY)
+		;
+
+	return 0;
+}
+
+static const struct mdio_ops fsl_ls_mdio_ops = {
+	.read = dm_fsl_ls_mdio_read,
+	.write = dm_fsl_ls_mdio_write,
+};
+
+static int fsl_ls_mdio_probe(struct udevice *dev)
+{
+	struct fsl_ls_mdio_priv *priv = dev_get_priv(dev);
+	struct memac_mdio_controller *regs;
+
+	priv->regs_base = dev_read_addr_ptr(dev);
+	regs = (struct memac_mdio_controller *)(priv->regs_base);
+
+	memac_setbits_32(&regs->mdio_stat,
+			 MDIO_STAT_CLKDIV(258) | MDIO_STAT_NEG);
+
+	return 0;
+}
+
+static const struct udevice_id fsl_ls_mdio_of_ids[] = {
+	{ .compatible = "fsl,ls-mdio" },
+};
+
+U_BOOT_DRIVER(fsl_ls_mdio) = {
+	.name = "fsl_ls_mdio",
+	.id = UCLASS_MDIO,
+	.of_match = fsl_ls_mdio_of_ids,
+	.probe = fsl_ls_mdio_probe,
+	.ops = &fsl_ls_mdio_ops,
+	.priv_auto_alloc_size = sizeof(struct fsl_ls_mdio_priv),
+};