1/*
  2 * MDIO bus driver for the Xilinx Axi Ethernet device
  3 *
  4 * Copyright (c) 2009 Secret Lab Technologies, Ltd.
  5 * Copyright (c) 2010 - 2011 Michal Simek <monstr@monstr.eu>
  6 * Copyright (c) 2010 - 2011 PetaLogix
  7 * Copyright (c) 2010 - 2012 Xilinx, Inc. All rights reserved.
  8 */
  9
 10#include <linux/of_address.h>
 11#include <linux/of_mdio.h>
 12#include <linux/jiffies.h>
 13
 14#include "xilinx_axienet.h"
 15
 16#define MAX_MDIO_FREQ		2500000 /* 2.5 MHz */
 17#define DEFAULT_CLOCK_DIVISOR	XAE_MDIO_DIV_DFT
 18
 19/* Wait till MDIO interface is ready to accept a new transaction.*/
 20int axienet_mdio_wait_until_ready(struct axienet_local *lp)
 21{
 22	unsigned long end = jiffies + 2;
 23	while (!(axienet_ior(lp, XAE_MDIO_MCR_OFFSET) &
 24		 XAE_MDIO_MCR_READY_MASK)) {
 25		if (time_before_eq(end, jiffies)) {
 26			WARN_ON(1);
 27			return -ETIMEDOUT;
 28		}
 29		udelay(1);
 30	}
 31	return 0;
 32}
 33
 34/**
 35 * axienet_mdio_read - MDIO interface read function
 36 * @bus:	Pointer to mii bus structure
 37 * @phy_id:	Address of the PHY device
 38 * @reg:	PHY register to read
 39 *
 40 * Return:	The register contents on success, -ETIMEDOUT on a timeout
 41 *
 42 * Reads the contents of the requested register from the requested PHY
 43 * address by first writing the details into MCR register. After a while
 44 * the register MRD is read to obtain the PHY register content.
 45 */
 46static int axienet_mdio_read(struct mii_bus *bus, int phy_id, int reg)
 47{
 48	u32 rc;
 49	int ret;
 50	struct axienet_local *lp = bus->priv;
 51
 52	ret = axienet_mdio_wait_until_ready(lp);
 53	if (ret < 0)
 54		return ret;
 55
 56	axienet_iow(lp, XAE_MDIO_MCR_OFFSET,
 57		    (((phy_id << XAE_MDIO_MCR_PHYAD_SHIFT) &
 58		      XAE_MDIO_MCR_PHYAD_MASK) |
 59		     ((reg << XAE_MDIO_MCR_REGAD_SHIFT) &
 60		      XAE_MDIO_MCR_REGAD_MASK) |
 61		     XAE_MDIO_MCR_INITIATE_MASK |
 62		     XAE_MDIO_MCR_OP_READ_MASK));
 63
 64	ret = axienet_mdio_wait_until_ready(lp);
 65	if (ret < 0)
 66		return ret;
 67
 68	rc = axienet_ior(lp, XAE_MDIO_MRD_OFFSET) & 0x0000FFFF;
 69
 70	dev_dbg(lp->dev, "axienet_mdio_read(phy_id=%i, reg=%x) == %x\n",
 71		phy_id, reg, rc);
 72
 73	return rc;
 74}
 75
 76/**
 77 * axienet_mdio_write - MDIO interface write function
 78 * @bus:	Pointer to mii bus structure
 79 * @phy_id:	Address of the PHY device
 80 * @reg:	PHY register to write to
 81 * @val:	Value to be written into the register
 82 *
 83 * Return:	0 on success, -ETIMEDOUT on a timeout
 84 *
 85 * Writes the value to the requested register by first writing the value
 86 * into MWD register. The the MCR register is then appropriately setup
 87 * to finish the write operation.
 88 */
 89static int axienet_mdio_write(struct mii_bus *bus, int phy_id, int reg,
 90			      u16 val)
 91{
 92	int ret;
 93	struct axienet_local *lp = bus->priv;
 94
 95	dev_dbg(lp->dev, "axienet_mdio_write(phy_id=%i, reg=%x, val=%x)\n",
 96		phy_id, reg, val);
 97
 98	ret = axienet_mdio_wait_until_ready(lp);
 99	if (ret < 0)
100		return ret;
101
102	axienet_iow(lp, XAE_MDIO_MWD_OFFSET, (u32) val);
103	axienet_iow(lp, XAE_MDIO_MCR_OFFSET,
104		    (((phy_id << XAE_MDIO_MCR_PHYAD_SHIFT) &
105		      XAE_MDIO_MCR_PHYAD_MASK) |
106		     ((reg << XAE_MDIO_MCR_REGAD_SHIFT) &
107		      XAE_MDIO_MCR_REGAD_MASK) |
108		     XAE_MDIO_MCR_INITIATE_MASK |
109		     XAE_MDIO_MCR_OP_WRITE_MASK));
110
111	ret = axienet_mdio_wait_until_ready(lp);
112	if (ret < 0)
113		return ret;
114	return 0;
115}
116
117/**
118 * axienet_mdio_setup - MDIO setup function
119 * @lp:		Pointer to axienet local data structure.
120 * @np:		Pointer to device node
121 *
122 * Return:	0 on success, -ETIMEDOUT on a timeout, -ENOMEM when
123 *		mdiobus_alloc (to allocate memory for mii bus structure) fails.
124 *
125 * Sets up the MDIO interface by initializing the MDIO clock and enabling the
126 * MDIO interface in hardware. Register the MDIO interface.
127 **/
128int axienet_mdio_setup(struct axienet_local *lp, struct device_node *np)
129{
130	int ret;
131	u32 clk_div, host_clock;
132	struct mii_bus *bus;
133	struct resource res;
134	struct device_node *np1;
135
136	/* clk_div can be calculated by deriving it from the equation:
137	 * fMDIO = fHOST / ((1 + clk_div) * 2)
138	 *
139	 * Where fMDIO <= 2500000, so we get:
140	 * fHOST / ((1 + clk_div) * 2) <= 2500000
141	 *
142	 * Then we get:
143	 * 1 / ((1 + clk_div) * 2) <= (2500000 / fHOST)
144	 *
145	 * Then we get:
146	 * 1 / (1 + clk_div) <= ((2500000 * 2) / fHOST)
147	 *
148	 * Then we get:
149	 * 1 / (1 + clk_div) <= (5000000 / fHOST)
150	 *
151	 * So:
152	 * (1 + clk_div) >= (fHOST / 5000000)
153	 *
154	 * And finally:
155	 * clk_div >= (fHOST / 5000000) - 1
156	 *
157	 * fHOST can be read from the flattened device tree as property
158	 * "clock-frequency" from the CPU
159	 */
160
161	np1 = of_find_node_by_name(NULL, "cpu");
162	if (!np1) {
163		netdev_warn(lp->ndev, "Could not find CPU device node.\n");
164		netdev_warn(lp->ndev,
165			    "Setting MDIO clock divisor to default %d\n",
166			    DEFAULT_CLOCK_DIVISOR);
167		clk_div = DEFAULT_CLOCK_DIVISOR;
168		goto issue;
169	}
170	if (of_property_read_u32(np1, "clock-frequency", &host_clock)) {
171		netdev_warn(lp->ndev, "clock-frequency property not found.\n");
172		netdev_warn(lp->ndev,
173			    "Setting MDIO clock divisor to default %d\n",
174			    DEFAULT_CLOCK_DIVISOR);
175		clk_div = DEFAULT_CLOCK_DIVISOR;
176		of_node_put(np1);
177		goto issue;
178	}
179
180	clk_div = (host_clock / (MAX_MDIO_FREQ * 2)) - 1;
181	/* If there is any remainder from the division of
182	 * fHOST / (MAX_MDIO_FREQ * 2), then we need to add
183	 * 1 to the clock divisor or we will surely be above 2.5 MHz
184	 */
185	if (host_clock % (MAX_MDIO_FREQ * 2))
186		clk_div++;
187
188	netdev_dbg(lp->ndev,
189		   "Setting MDIO clock divisor to %u/%u Hz host clock.\n",
190		   clk_div, host_clock);
191
192	of_node_put(np1);
193issue:
194	axienet_iow(lp, XAE_MDIO_MC_OFFSET,
195		    (((u32) clk_div) | XAE_MDIO_MC_MDIOEN_MASK));
196
197	ret = axienet_mdio_wait_until_ready(lp);
198	if (ret < 0)
199		return ret;
200
201	bus = mdiobus_alloc();
202	if (!bus)
203		return -ENOMEM;
204
205	np1 = of_get_parent(lp->phy_node);
206	of_address_to_resource(np1, 0, &res);
207	snprintf(bus->id, MII_BUS_ID_SIZE, "%.8llx",
208		 (unsigned long long) res.start);
209
210	bus->priv = lp;
211	bus->name = "Xilinx Axi Ethernet MDIO";
212	bus->read = axienet_mdio_read;
213	bus->write = axienet_mdio_write;
214	bus->parent = lp->dev;
215	lp->mii_bus = bus;
216
217	ret = of_mdiobus_register(bus, np1);
218	if (ret) {
219		mdiobus_free(bus);
220		return ret;
221	}
222	return 0;
223}
224
225/**
226 * axienet_mdio_teardown - MDIO remove function
227 * @lp:		Pointer to axienet local data structure.
228 *
229 * Unregisters the MDIO and frees any associate memory for mii bus.
230 */
231void axienet_mdio_teardown(struct axienet_local *lp)
232{
233	mdiobus_unregister(lp->mii_bus);
234	mdiobus_free(lp->mii_bus);
235	lp->mii_bus = NULL;
236}