1/*
  2 * Broadcom UniMAC MDIO bus controller driver
  3 *
  4 * Copyright (C) 2014-2017 Broadcom
  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#include <linux/platform_data/mdio-bcm-unimac.h>
 25
 26#define MDIO_CMD		0x00
 27#define  MDIO_START_BUSY	(1 << 29)
 28#define  MDIO_READ_FAIL		(1 << 28)
 29#define  MDIO_RD		(2 << 26)
 30#define  MDIO_WR		(1 << 26)
 31#define  MDIO_PMD_SHIFT		21
 32#define  MDIO_PMD_MASK		0x1F
 33#define  MDIO_REG_SHIFT		16
 34#define  MDIO_REG_MASK		0x1F
 35
 36#define MDIO_CFG		0x04
 37#define  MDIO_C22		(1 << 0)
 38#define  MDIO_C45		0
 39#define  MDIO_CLK_DIV_SHIFT	4
 40#define  MDIO_CLK_DIV_MASK	0x3F
 41#define  MDIO_SUPP_PREAMBLE	(1 << 12)
 42
 43struct unimac_mdio_priv {
 44	struct mii_bus		*mii_bus;
 45	void __iomem		*base;
 46	int (*wait_func)	(void *wait_func_data);
 47	void			*wait_func_data;
 48};
 49
 50static inline u32 unimac_mdio_readl(struct unimac_mdio_priv *priv, u32 offset)
 51{
 52	/* MIPS chips strapped for BE will automagically configure the
 53	 * peripheral registers for CPU-native byte order.
 54	 */
 55	if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
 56		return __raw_readl(priv->base + offset);
 57	else
 58		return readl_relaxed(priv->base + offset);
 59}
 60
 61static inline void unimac_mdio_writel(struct unimac_mdio_priv *priv, u32 val,
 62				      u32 offset)
 63{
 64	if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
 65		__raw_writel(val, priv->base + offset);
 66	else
 67		writel_relaxed(val, priv->base + offset);
 68}
 69
 70static inline void unimac_mdio_start(struct unimac_mdio_priv *priv)
 71{
 72	u32 reg;
 73
 74	reg = unimac_mdio_readl(priv, MDIO_CMD);
 75	reg |= MDIO_START_BUSY;
 76	unimac_mdio_writel(priv, reg, MDIO_CMD);
 77}
 78
 79static inline unsigned int unimac_mdio_busy(struct unimac_mdio_priv *priv)
 80{
 81	return unimac_mdio_readl(priv, MDIO_CMD) & MDIO_START_BUSY;
 82}
 83
 84static int unimac_mdio_poll(void *wait_func_data)
 85{
 86	struct unimac_mdio_priv *priv = wait_func_data;
 87	unsigned int timeout = 1000;
 88
 89	do {
 90		if (!unimac_mdio_busy(priv))
 91			return 0;
 92
 93		usleep_range(1000, 2000);
 94	} while (--timeout);
 95
 96	if (!timeout)
 97		return -ETIMEDOUT;
 98
 99	return 0;
100}
101
102static int unimac_mdio_read(struct mii_bus *bus, int phy_id, int reg)
103{
104	struct unimac_mdio_priv *priv = bus->priv;
105	int ret;
106	u32 cmd;
107
108	/* Prepare the read operation */
109	cmd = MDIO_RD | (phy_id << MDIO_PMD_SHIFT) | (reg << MDIO_REG_SHIFT);
110	unimac_mdio_writel(priv, cmd, MDIO_CMD);
111
112	/* Start MDIO transaction */
113	unimac_mdio_start(priv);
114
115	ret = priv->wait_func(priv->wait_func_data);
116	if (ret)
117		return ret;
118
119	cmd = unimac_mdio_readl(priv, MDIO_CMD);
120
121	/* Some broken devices are known not to release the line during
122	 * turn-around, e.g: Broadcom BCM53125 external switches, so check for
123	 * that condition here and ignore the MDIO controller read failure
124	 * indication.
125	 */
126	if (!(bus->phy_ignore_ta_mask & 1 << phy_id) && (cmd & MDIO_READ_FAIL))
127		return -EIO;
128
129	return cmd & 0xffff;
130}
131
132static int unimac_mdio_write(struct mii_bus *bus, int phy_id,
133			     int reg, u16 val)
134{
135	struct unimac_mdio_priv *priv = bus->priv;
136	u32 cmd;
137
138	/* Prepare the write operation */
139	cmd = MDIO_WR | (phy_id << MDIO_PMD_SHIFT) |
140		(reg << MDIO_REG_SHIFT) | (0xffff & val);
141	unimac_mdio_writel(priv, cmd, MDIO_CMD);
142
143	unimac_mdio_start(priv);
144
145	return priv->wait_func(priv->wait_func_data);
146}
147
148/* Workaround for integrated BCM7xxx Gigabit PHYs which have a problem with
149 * their internal MDIO management controller making them fail to successfully
150 * be read from or written to for the first transaction.  We insert a dummy
151 * BMSR read here to make sure that phy_get_device() and get_phy_id() can
152 * correctly read the PHY MII_PHYSID1/2 registers and successfully register a
153 * PHY device for this peripheral.
154 *
155 * Once the PHY driver is registered, we can workaround subsequent reads from
156 * there (e.g: during system-wide power management).
157 *
158 * bus->reset is invoked before mdiobus_scan during mdiobus_register and is
159 * therefore the right location to stick that workaround. Since we do not want
160 * to read from non-existing PHYs, we either use bus->phy_mask or do a manual
161 * Device Tree scan to limit the search area.
162 */
163static int unimac_mdio_reset(struct mii_bus *bus)
164{
165	struct device_node *np = bus->dev.of_node;
166	struct device_node *child;
167	u32 read_mask = 0;
168	int addr;
169
170	if (!np) {
171		read_mask = ~bus->phy_mask;
172	} else {
173		for_each_available_child_of_node(np, child) {
174			addr = of_mdio_parse_addr(&bus->dev, child);
175			if (addr < 0)
176				continue;
177
178			read_mask |= 1 << addr;
179		}
180	}
181
182	for (addr = 0; addr < PHY_MAX_ADDR; addr++) {
183		if (read_mask & 1 << addr) {
184			dev_dbg(&bus->dev, "Workaround for PHY @ %d\n", addr);
185			mdiobus_read(bus, addr, MII_BMSR);
186		}
187	}
188
189	return 0;
190}
191
192static int unimac_mdio_probe(struct platform_device *pdev)
193{
194	struct unimac_mdio_pdata *pdata = pdev->dev.platform_data;
195	struct unimac_mdio_priv *priv;
196	struct device_node *np;
197	struct mii_bus *bus;
198	struct resource *r;
199	int ret;
200
201	np = pdev->dev.of_node;
202
203	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
204	if (!priv)
205		return -ENOMEM;
206
207	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
208	if (!r)
209		return -EINVAL;
210
211	/* Just ioremap, as this MDIO block is usually integrated into an
212	 * Ethernet MAC controller register range
213	 */
214	priv->base = devm_ioremap(&pdev->dev, r->start, resource_size(r));
215	if (!priv->base) {
216		dev_err(&pdev->dev, "failed to remap register\n");
217		return -ENOMEM;
218	}
219
220	priv->mii_bus = mdiobus_alloc();
221	if (!priv->mii_bus)
222		return -ENOMEM;
223
224	bus = priv->mii_bus;
225	bus->priv = priv;
226	if (pdata) {
227		bus->name = pdata->bus_name;
228		priv->wait_func = pdata->wait_func;
229		priv->wait_func_data = pdata->wait_func_data;
230		bus->phy_mask = ~pdata->phy_mask;
231	} else {
232		bus->name = "unimac MII bus";
233		priv->wait_func_data = priv;
234		priv->wait_func = unimac_mdio_poll;
235	}
236	bus->parent = &pdev->dev;
237	bus->read = unimac_mdio_read;
238	bus->write = unimac_mdio_write;
239	bus->reset = unimac_mdio_reset;
240	snprintf(bus->id, MII_BUS_ID_SIZE, "%s-%d", pdev->name, pdev->id);
241
242	ret = of_mdiobus_register(bus, np);
243	if (ret) {
244		dev_err(&pdev->dev, "MDIO bus registration failed\n");
245		goto out_mdio_free;
246	}
247
248	platform_set_drvdata(pdev, priv);
249
250	dev_info(&pdev->dev, "Broadcom UniMAC MDIO bus at 0x%p\n", priv->base);
251
252	return 0;
253
254out_mdio_free:
255	mdiobus_free(bus);
256	return ret;
257}
258
259static int unimac_mdio_remove(struct platform_device *pdev)
260{
261	struct unimac_mdio_priv *priv = platform_get_drvdata(pdev);
262
263	mdiobus_unregister(priv->mii_bus);
264	mdiobus_free(priv->mii_bus);
265
266	return 0;
267}
268
269static const struct of_device_id unimac_mdio_ids[] = {
270	{ .compatible = "brcm,genet-mdio-v5", },
271	{ .compatible = "brcm,genet-mdio-v4", },
272	{ .compatible = "brcm,genet-mdio-v3", },
273	{ .compatible = "brcm,genet-mdio-v2", },
274	{ .compatible = "brcm,genet-mdio-v1", },
275	{ .compatible = "brcm,unimac-mdio", },
276	{ /* sentinel */ },
277};
278MODULE_DEVICE_TABLE(of, unimac_mdio_ids);
279
280static struct platform_driver unimac_mdio_driver = {
281	.driver = {
282		.name = UNIMAC_MDIO_DRV_NAME,
283		.of_match_table = unimac_mdio_ids,
284	},
285	.probe	= unimac_mdio_probe,
286	.remove	= unimac_mdio_remove,
287};
288module_platform_driver(unimac_mdio_driver);
289
290MODULE_AUTHOR("Broadcom Corporation");
291MODULE_DESCRIPTION("Broadcom UniMAC MDIO bus controller");
292MODULE_LICENSE("GPL");
293MODULE_ALIAS("platform:" UNIMAC_MDIO_DRV_NAME);