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// SPDX-License-Identifier: GPL-2.0
/*
* MDIO bus driver for the Xilinx Axi Ethernet device
*
* Copyright (c) 2009 Secret Lab Technologies, Ltd.
* Copyright (c) 2010 - 2011 Michal Simek <monstr@monstr.eu>
* Copyright (c) 2010 - 2011 PetaLogix
* Copyright (c) 2010 - 2012 Xilinx, Inc. All rights reserved.
*/
#include <linux/of_address.h>
#include <linux/of_mdio.h>
#include <linux/jiffies.h>
#include "xilinx_axienet.h"
#define MAX_MDIO_FREQ 2500000 /* 2.5 MHz */
#define DEFAULT_CLOCK_DIVISOR XAE_MDIO_DIV_DFT
/* Wait till MDIO interface is ready to accept a new transaction.*/
int axienet_mdio_wait_until_ready(struct axienet_local *lp)
{
unsigned long end = jiffies + 2;
while (!(axienet_ior(lp, XAE_MDIO_MCR_OFFSET) &
XAE_MDIO_MCR_READY_MASK)) {
if (time_before_eq(end, jiffies)) {
WARN_ON(1);
return -ETIMEDOUT;
}
udelay(1);
}
return 0;
}
/**
* axienet_mdio_read - MDIO interface read function
* @bus: Pointer to mii bus structure
* @phy_id: Address of the PHY device
* @reg: PHY register to read
*
* Return: The register contents on success, -ETIMEDOUT on a timeout
*
* Reads the contents of the requested register from the requested PHY
* address by first writing the details into MCR register. After a while
* the register MRD is read to obtain the PHY register content.
*/
static int axienet_mdio_read(struct mii_bus *bus, int phy_id, int reg)
{
u32 rc;
int ret;
struct axienet_local *lp = bus->priv;
ret = axienet_mdio_wait_until_ready(lp);
if (ret < 0)
return ret;
axienet_iow(lp, XAE_MDIO_MCR_OFFSET,
(((phy_id << XAE_MDIO_MCR_PHYAD_SHIFT) &
XAE_MDIO_MCR_PHYAD_MASK) |
((reg << XAE_MDIO_MCR_REGAD_SHIFT) &
XAE_MDIO_MCR_REGAD_MASK) |
XAE_MDIO_MCR_INITIATE_MASK |
XAE_MDIO_MCR_OP_READ_MASK));
ret = axienet_mdio_wait_until_ready(lp);
if (ret < 0)
return ret;
rc = axienet_ior(lp, XAE_MDIO_MRD_OFFSET) & 0x0000FFFF;
dev_dbg(lp->dev, "axienet_mdio_read(phy_id=%i, reg=%x) == %x\n",
phy_id, reg, rc);
return rc;
}
/**
* axienet_mdio_write - MDIO interface write function
* @bus: Pointer to mii bus structure
* @phy_id: Address of the PHY device
* @reg: PHY register to write to
* @val: Value to be written into the register
*
* Return: 0 on success, -ETIMEDOUT on a timeout
*
* Writes the value to the requested register by first writing the value
* into MWD register. The the MCR register is then appropriately setup
* to finish the write operation.
*/
static int axienet_mdio_write(struct mii_bus *bus, int phy_id, int reg,
u16 val)
{
int ret;
struct axienet_local *lp = bus->priv;
dev_dbg(lp->dev, "axienet_mdio_write(phy_id=%i, reg=%x, val=%x)\n",
phy_id, reg, val);
ret = axienet_mdio_wait_until_ready(lp);
if (ret < 0)
return ret;
axienet_iow(lp, XAE_MDIO_MWD_OFFSET, (u32) val);
axienet_iow(lp, XAE_MDIO_MCR_OFFSET,
(((phy_id << XAE_MDIO_MCR_PHYAD_SHIFT) &
XAE_MDIO_MCR_PHYAD_MASK) |
((reg << XAE_MDIO_MCR_REGAD_SHIFT) &
XAE_MDIO_MCR_REGAD_MASK) |
XAE_MDIO_MCR_INITIATE_MASK |
XAE_MDIO_MCR_OP_WRITE_MASK));
ret = axienet_mdio_wait_until_ready(lp);
if (ret < 0)
return ret;
return 0;
}
/**
* axienet_mdio_setup - MDIO setup function
* @lp: Pointer to axienet local data structure.
* @np: Pointer to device node
*
* Return: 0 on success, -ETIMEDOUT on a timeout, -ENOMEM when
* mdiobus_alloc (to allocate memory for mii bus structure) fails.
*
* Sets up the MDIO interface by initializing the MDIO clock and enabling the
* MDIO interface in hardware. Register the MDIO interface.
**/
int axienet_mdio_setup(struct axienet_local *lp, struct device_node *np)
{
int ret;
u32 clk_div, host_clock;
struct mii_bus *bus;
struct resource res;
struct device_node *np1;
/* clk_div can be calculated by deriving it from the equation:
* fMDIO = fHOST / ((1 + clk_div) * 2)
*
* Where fMDIO <= 2500000, so we get:
* fHOST / ((1 + clk_div) * 2) <= 2500000
*
* Then we get:
* 1 / ((1 + clk_div) * 2) <= (2500000 / fHOST)
*
* Then we get:
* 1 / (1 + clk_div) <= ((2500000 * 2) / fHOST)
*
* Then we get:
* 1 / (1 + clk_div) <= (5000000 / fHOST)
*
* So:
* (1 + clk_div) >= (fHOST / 5000000)
*
* And finally:
* clk_div >= (fHOST / 5000000) - 1
*
* fHOST can be read from the flattened device tree as property
* "clock-frequency" from the CPU
*/
np1 = of_find_node_by_name(NULL, "cpu");
if (!np1) {
netdev_warn(lp->ndev, "Could not find CPU device node.\n");
netdev_warn(lp->ndev,
"Setting MDIO clock divisor to default %d\n",
DEFAULT_CLOCK_DIVISOR);
clk_div = DEFAULT_CLOCK_DIVISOR;
goto issue;
}
if (of_property_read_u32(np1, "clock-frequency", &host_clock)) {
netdev_warn(lp->ndev, "clock-frequency property not found.\n");
netdev_warn(lp->ndev,
"Setting MDIO clock divisor to default %d\n",
DEFAULT_CLOCK_DIVISOR);
clk_div = DEFAULT_CLOCK_DIVISOR;
of_node_put(np1);
goto issue;
}
clk_div = (host_clock / (MAX_MDIO_FREQ * 2)) - 1;
/* If there is any remainder from the division of
* fHOST / (MAX_MDIO_FREQ * 2), then we need to add
* 1 to the clock divisor or we will surely be above 2.5 MHz
*/
if (host_clock % (MAX_MDIO_FREQ * 2))
clk_div++;
netdev_dbg(lp->ndev,
"Setting MDIO clock divisor to %u/%u Hz host clock.\n",
clk_div, host_clock);
of_node_put(np1);
issue:
axienet_iow(lp, XAE_MDIO_MC_OFFSET,
(((u32) clk_div) | XAE_MDIO_MC_MDIOEN_MASK));
ret = axienet_mdio_wait_until_ready(lp);
if (ret < 0)
return ret;
bus = mdiobus_alloc();
if (!bus)
return -ENOMEM;
np1 = of_get_parent(lp->phy_node);
of_address_to_resource(np1, 0, &res);
snprintf(bus->id, MII_BUS_ID_SIZE, "%.8llx",
(unsigned long long) res.start);
bus->priv = lp;
bus->name = "Xilinx Axi Ethernet MDIO";
bus->read = axienet_mdio_read;
bus->write = axienet_mdio_write;
bus->parent = lp->dev;
lp->mii_bus = bus;
ret = of_mdiobus_register(bus, np1);
if (ret) {
mdiobus_free(bus);
lp->mii_bus = NULL;
return ret;
}
return 0;
}
/**
* axienet_mdio_teardown - MDIO remove function
* @lp: Pointer to axienet local data structure.
*
* Unregisters the MDIO and frees any associate memory for mii bus.
*/
void axienet_mdio_teardown(struct axienet_local *lp)
{
mdiobus_unregister(lp->mii_bus);
mdiobus_free(lp->mii_bus);
lp->mii_bus = NULL;
}
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