driver: net: ti: introduce common mdio support library

All existing TI SoCs network HW have similar MDIO implementation, so
introduce common mdio support library which can be reused by TI networking
drivers.

Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

drivers/net/ti/Makefile

@@ -2,6 +2,6 @@
 #
 # Copyright (C) 2018 Texas Instruments Incorporated - http://www.ti.com/
 
-obj-$(CONFIG_DRIVER_TI_CPSW) += cpsw.o cpsw-common.o
+obj-$(CONFIG_DRIVER_TI_CPSW) += cpsw.o cpsw-common.o cpsw_mdio.o
 obj-$(CONFIG_DRIVER_TI_EMAC) += davinci_emac.o
 obj-$(CONFIG_DRIVER_TI_KEYSTONE_NET) += keystone_net.o

drivers/net/ti/cpsw_mdio.c

@@ -0,0 +1,203 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * CPSW MDIO generic driver for TI AMxx/K2x/EMAC devices.
+ *
+ * Copyright (C) 2018 Texas Instruments Incorporated - http://www.ti.com/
+ */
+
+#include <common.h>
+#include <asm/io.h>
+#include <miiphy.h>
+#include <wait_bit.h>
+
+struct cpsw_mdio_regs {
+	u32	version;
+	u32	control;
+#define CONTROL_IDLE		BIT(31)
+#define CONTROL_ENABLE		BIT(30)
+#define CONTROL_FAULT		BIT(19)
+#define CONTROL_FAULT_ENABLE	BIT(18)
+#define CONTROL_DIV_MASK	GENMASK(15, 0)
+
+	u32	alive;
+	u32	link;
+	u32	linkintraw;
+	u32	linkintmasked;
+	u32	__reserved_0[2];
+	u32	userintraw;
+	u32	userintmasked;
+	u32	userintmaskset;
+	u32	userintmaskclr;
+	u32	__reserved_1[20];
+
+	struct {
+		u32		access;
+		u32		physel;
+#define USERACCESS_GO		BIT(31)
+#define USERACCESS_WRITE	BIT(30)
+#define USERACCESS_ACK		BIT(29)
+#define USERACCESS_READ		(0)
+#define USERACCESS_PHY_REG_SHIFT	(21)
+#define USERACCESS_PHY_ADDR_SHIFT	(16)
+#define USERACCESS_DATA		GENMASK(15, 0)
+	} user[0];
+};
+
+#define CPSW_MDIO_DIV_DEF	0xff
+#define PHY_REG_MASK		0x1f
+#define PHY_ID_MASK		0x1f
+
+/*
+ * This timeout definition is a worst-case ultra defensive measure against
+ * unexpected controller lock ups.  Ideally, we should never ever hit this
+ * scenario in practice.
+ */
+#define CPSW_MDIO_TIMEOUT            100 /* msecs */
+
+struct cpsw_mdio {
+	struct cpsw_mdio_regs *regs;
+	struct mii_dev *bus;
+	int div;
+};
+
+/* wait until hardware is ready for another user access */
+static int cpsw_mdio_wait_for_user_access(struct cpsw_mdio *mdio)
+{
+	return wait_for_bit_le32(&mdio->regs->user[0].access,
+				 USERACCESS_GO, false,
+				 CPSW_MDIO_TIMEOUT, false);
+}
+
+static int cpsw_mdio_read(struct mii_dev *bus, int phy_id,
+			  int dev_addr, int phy_reg)
+{
+	struct cpsw_mdio *mdio = bus->priv;
+	int data, ret;
+	u32 reg;
+
+	if (phy_reg & ~PHY_REG_MASK || phy_id & ~PHY_ID_MASK)
+		return -EINVAL;
+
+	ret = cpsw_mdio_wait_for_user_access(mdio);
+	if (ret)
+		return ret;
+	reg = (USERACCESS_GO | USERACCESS_READ |
+	       (phy_reg << USERACCESS_PHY_REG_SHIFT) |
+	       (phy_id << USERACCESS_PHY_ADDR_SHIFT));
+	writel(reg, &mdio->regs->user[0].access);
+	ret = cpsw_mdio_wait_for_user_access(mdio);
+	if (ret)
+		return ret;
+
+	reg = readl(&mdio->regs->user[0].access);
+	data = (reg & USERACCESS_ACK) ? (reg & USERACCESS_DATA) : -1;
+	return data;
+}
+
+static int cpsw_mdio_write(struct mii_dev *bus, int phy_id, int dev_addr,
+			   int phy_reg, u16 data)
+{
+	struct cpsw_mdio *mdio = bus->priv;
+	u32 reg;
+	int ret;
+
+	if (phy_reg & ~PHY_REG_MASK || phy_id & ~PHY_ID_MASK)
+		return -EINVAL;
+
+	ret = cpsw_mdio_wait_for_user_access(mdio);
+	if (ret)
+		return ret;
+	reg = (USERACCESS_GO | USERACCESS_WRITE |
+	       (phy_reg << USERACCESS_PHY_REG_SHIFT) |
+	       (phy_id << USERACCESS_PHY_ADDR_SHIFT) |
+	       (data & USERACCESS_DATA));
+	writel(reg, &mdio->regs->user[0].access);
+
+	return cpsw_mdio_wait_for_user_access(mdio);
+}
+
+u32 cpsw_mdio_get_alive(struct mii_dev *bus)
+{
+	struct cpsw_mdio *mdio = bus->priv;
+	u32 val;
+
+	val = readl(&mdio->regs->control);
+	return val & GENMASK(15, 0);
+}
+
+struct mii_dev *cpsw_mdio_init(const char *name, u32 mdio_base,
+			       u32 bus_freq, int fck_freq)
+{
+	struct cpsw_mdio *cpsw_mdio;
+	int ret;
+
+	cpsw_mdio = calloc(1, sizeof(*cpsw_mdio));
+	if (!cpsw_mdio) {
+		debug("failed to alloc cpsw_mdio\n");
+		return NULL;
+	}
+
+	cpsw_mdio->bus = mdio_alloc();
+	if (!cpsw_mdio->bus) {
+		debug("failed to alloc mii bus\n");
+		free(cpsw_mdio);
+		return NULL;
+	}
+
+	cpsw_mdio->regs = (struct cpsw_mdio_regs *)mdio_base;
+
+	if (!bus_freq || !fck_freq)
+		cpsw_mdio->div = CPSW_MDIO_DIV_DEF;
+	else
+		cpsw_mdio->div = (fck_freq / bus_freq) - 1;
+	cpsw_mdio->div &= CONTROL_DIV_MASK;
+
+	/* set enable and clock divider */
+	writel(cpsw_mdio->div | CONTROL_ENABLE | CONTROL_FAULT |
+	       CONTROL_FAULT_ENABLE, &cpsw_mdio->regs->control);
+	wait_for_bit_le32(&cpsw_mdio->regs->control,
+			  CONTROL_IDLE, false, CPSW_MDIO_TIMEOUT, true);
+
+	/*
+	 * wait for scan logic to settle:
+	 * the scan time consists of (a) a large fixed component, and (b) a
+	 * small component that varies with the mii bus frequency.  These
+	 * were estimated using measurements at 1.1 and 2.2 MHz on tnetv107x
+	 * silicon.  Since the effect of (b) was found to be largely
+	 * negligible, we keep things simple here.
+	 */
+	mdelay(1);
+
+	cpsw_mdio->bus->read = cpsw_mdio_read;
+	cpsw_mdio->bus->write = cpsw_mdio_write;
+	cpsw_mdio->bus->priv = cpsw_mdio;
+	snprintf(cpsw_mdio->bus->name, sizeof(cpsw_mdio->bus->name), name);
+
+	ret = mdio_register(cpsw_mdio->bus);
+	if (ret < 0) {
+		debug("failed to register mii bus\n");
+		goto free_bus;
+	}
+
+	return cpsw_mdio->bus;
+
+free_bus:
+	mdio_free(cpsw_mdio->bus);
+	free(cpsw_mdio);
+	return NULL;
+}
+
+void cpsw_mdio_free(struct mii_dev *bus)
+{
+	struct cpsw_mdio *mdio = bus->priv;
+	u32 reg;
+
+	/* disable mdio */
+	reg = readl(&mdio->regs->control);
+	reg &= ~CONTROL_ENABLE;
+	writel(reg, &mdio->regs->control);
+
+	mdio_unregister(bus);
+	mdio_free(bus);
+	free(mdio);
+}

drivers/net/ti/cpsw_mdio.h

@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * CPSW MDIO generic driver API for TI AMxx/K2x/EMAC devices.
+ *
+ * Copyright (C) 2018 Texas Instruments Incorporated - http://www.ti.com/
+ */
+
+#ifndef CPSW_MDIO_H_
+#define CPSW_MDIO_H_
+
+struct cpsw_mdio;
+
+struct mii_dev *cpsw_mdio_init(const char *name, u32 mdio_base,
+			       u32 bus_freq, int fck_freq);
+void cpsw_mdio_free(struct mii_dev *bus);
+u32 cpsw_mdio_get_alive(struct mii_dev *bus);
+
+#endif /* CPSW_MDIO_H_ */