1/*
2 * Broadcom UniMAC MDIO bus controller driver
3 *
4 * Copyright (C) 2014, Broadcom Corporation
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 */
11
12#include <linux/kernel.h>
13#include <linux/phy.h>
14#include <linux/platform_device.h>
15#include <linux/sched.h>
16#include <linux/module.h>
17#include <linux/io.h>
18#include <linux/delay.h>
19
20#include <linux/of.h>
21#include <linux/of_platform.h>
22#include <linux/of_mdio.h>
23
24#define MDIO_CMD		0x00
25#define  MDIO_START_BUSY	(1 << 29)
26#define  MDIO_READ_FAIL		(1 << 28)
27#define  MDIO_RD		(2 << 26)
28#define  MDIO_WR		(1 << 26)
29#define  MDIO_PMD_SHIFT		21
30#define  MDIO_PMD_MASK		0x1F
31#define  MDIO_REG_SHIFT		16
32#define  MDIO_REG_MASK		0x1F
33
34#define MDIO_CFG		0x04
35#define  MDIO_C22		(1 << 0)
36#define  MDIO_C45		0
37#define  MDIO_CLK_DIV_SHIFT	4
38#define  MDIO_CLK_DIV_MASK	0x3F
39#define  MDIO_SUPP_PREAMBLE	(1 << 12)
40
41struct unimac_mdio_priv {
42	struct mii_bus		*mii_bus;
43	void __iomem		*base;
44};
45
46static inline void unimac_mdio_start(struct unimac_mdio_priv *priv)
47{
48	u32 reg;
49
50	reg = __raw_readl(priv->base + MDIO_CMD);
51	reg |= MDIO_START_BUSY;
52	__raw_writel(reg, priv->base + MDIO_CMD);
53}
54
55static inline unsigned int unimac_mdio_busy(struct unimac_mdio_priv *priv)
56{
57	return __raw_readl(priv->base + MDIO_CMD) & MDIO_START_BUSY;
58}
59
60static int unimac_mdio_read(struct mii_bus *bus, int phy_id, int reg)
61{
62	struct unimac_mdio_priv *priv = bus->priv;
63	unsigned int timeout = 1000;
64	u32 cmd;
65
66	/* Prepare the read operation */
67	cmd = MDIO_RD | (phy_id << MDIO_PMD_SHIFT) | (reg << MDIO_REG_SHIFT);
68	__raw_writel(cmd, priv->base + MDIO_CMD);
69
70	/* Start MDIO transaction */
71	unimac_mdio_start(priv);
72
73	do {
74		if (!unimac_mdio_busy(priv))
75			break;
76
77		usleep_range(1000, 2000);
78	} while (timeout--);
79
80	if (!timeout)
81		return -ETIMEDOUT;
82
83	cmd = __raw_readl(priv->base + MDIO_CMD);
84
85	/* Some broken devices are known not to release the line during
86	 * turn-around, e.g: Broadcom BCM53125 external switches, so check for
87	 * that condition here and ignore the MDIO controller read failure
88	 * indication.
89	 */
90	if (!(bus->phy_ignore_ta_mask & 1 << phy_id) && (cmd & MDIO_READ_FAIL))
91		return -EIO;
92
93	return cmd & 0xffff;
94}
95
96static int unimac_mdio_write(struct mii_bus *bus, int phy_id,
97			     int reg, u16 val)
98{
99	struct unimac_mdio_priv *priv = bus->priv;
100	unsigned int timeout = 1000;
101	u32 cmd;
102
103	/* Prepare the write operation */
104	cmd = MDIO_WR | (phy_id << MDIO_PMD_SHIFT) |
105		(reg << MDIO_REG_SHIFT) | (0xffff & val);
106	__raw_writel(cmd, priv->base + MDIO_CMD);
107
108	unimac_mdio_start(priv);
109
110	do {
111		if (!unimac_mdio_busy(priv))
112			break;
113
114		usleep_range(1000, 2000);
115	} while (timeout--);
116
117	if (!timeout)
118		return -ETIMEDOUT;
119
120	return 0;
121}
122
123/* Workaround for integrated BCM7xxx Gigabit PHYs which have a problem with
124 * their internal MDIO management controller making them fail to successfully
125 * be read from or written to for the first transaction.  We insert a dummy
126 * BMSR read here to make sure that phy_get_device() and get_phy_id() can
127 * correctly read the PHY MII_PHYSID1/2 registers and successfully register a
128 * PHY device for this peripheral.
129 *
130 * Once the PHY driver is registered, we can workaround subsequent reads from
131 * there (e.g: during system-wide power management).
132 *
133 * bus->reset is invoked before mdiobus_scan during mdiobus_register and is
134 * therefore the right location to stick that workaround. Since we do not want
135 * to read from non-existing PHYs, we either use bus->phy_mask or do a manual
136 * Device Tree scan to limit the search area.
137 */
138static int unimac_mdio_reset(struct mii_bus *bus)
139{
140	struct device_node *np = bus->dev.of_node;
141	struct device_node *child;
142	u32 read_mask = 0;
143	int addr;
144
145	if (!np) {
146		read_mask = ~bus->phy_mask;
147	} else {
148		for_each_available_child_of_node(np, child) {
149			addr = of_mdio_parse_addr(&bus->dev, child);
150			if (addr < 0)
151				continue;
152
153			read_mask |= 1 << addr;
154		}
155	}
156
157	for (addr = 0; addr < PHY_MAX_ADDR; addr++) {
158		if (read_mask & 1 << addr)
159			mdiobus_read(bus, addr, MII_BMSR);
160	}
161
162	return 0;
163}
164
165static int unimac_mdio_probe(struct platform_device *pdev)
166{
167	struct unimac_mdio_priv *priv;
168	struct device_node *np;
169	struct mii_bus *bus;
170	struct resource *r;
171	int ret;
172
173	np = pdev->dev.of_node;
174
175	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
176	if (!priv)
177		return -ENOMEM;
178
179	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
180
181	/* Just ioremap, as this MDIO block is usually integrated into an
182	 * Ethernet MAC controller register range
183	 */
184	priv->base = devm_ioremap(&pdev->dev, r->start, resource_size(r));
185	if (!priv->base) {
186		dev_err(&pdev->dev, "failed to remap register\n");
187		return -ENOMEM;
188	}
189
190	priv->mii_bus = mdiobus_alloc();
191	if (!priv->mii_bus)
192		return -ENOMEM;
193
194	bus = priv->mii_bus;
195	bus->priv = priv;
196	bus->name = "unimac MII bus";
197	bus->parent = &pdev->dev;
198	bus->read = unimac_mdio_read;
199	bus->write = unimac_mdio_write;
200	bus->reset = unimac_mdio_reset;
201	snprintf(bus->id, MII_BUS_ID_SIZE, "%s", pdev->name);
202
203	bus->irq = kcalloc(PHY_MAX_ADDR, sizeof(int), GFP_KERNEL);
204	if (!bus->irq) {
205		ret = -ENOMEM;
206		goto out_mdio_free;
207	}
208
209	ret = of_mdiobus_register(bus, np);
210	if (ret) {
211		dev_err(&pdev->dev, "MDIO bus registration failed\n");
212		goto out_mdio_irq;
213	}
214
215	platform_set_drvdata(pdev, priv);
216
217	dev_info(&pdev->dev, "Broadcom UniMAC MDIO bus at 0x%p\n", priv->base);
218
219	return 0;
220
221out_mdio_irq:
222	kfree(bus->irq);
223out_mdio_free:
224	mdiobus_free(bus);
225	return ret;
226}
227
228static int unimac_mdio_remove(struct platform_device *pdev)
229{
230	struct unimac_mdio_priv *priv = platform_get_drvdata(pdev);
231
232	mdiobus_unregister(priv->mii_bus);
233	kfree(priv->mii_bus->irq);
234	mdiobus_free(priv->mii_bus);
235
236	return 0;
237}
238
239static const struct of_device_id unimac_mdio_ids[] = {
240	{ .compatible = "brcm,genet-mdio-v4", },
241	{ .compatible = "brcm,genet-mdio-v3", },
242	{ .compatible = "brcm,genet-mdio-v2", },
243	{ .compatible = "brcm,genet-mdio-v1", },
244	{ .compatible = "brcm,unimac-mdio", },
245	{ /* sentinel */ },
246};
247MODULE_DEVICE_TABLE(of, unimac_mdio_ids);
248
249static struct platform_driver unimac_mdio_driver = {
250	.driver = {
251		.name = "unimac-mdio",
252		.of_match_table = unimac_mdio_ids,
253	},
254	.probe	= unimac_mdio_probe,
255	.remove	= unimac_mdio_remove,
256};
257module_platform_driver(unimac_mdio_driver);
258
259MODULE_AUTHOR("Broadcom Corporation");
260MODULE_DESCRIPTION("Broadcom UniMAC MDIO bus controller");
261MODULE_LICENSE("GPL");
262MODULE_ALIAS("platform:unimac-mdio");
263