1// SPDX-License-Identifier: (GPL-2.0 OR MIT)
  2/*
  3 * Driver for the MDIO interface of Microsemi network switches.
  4 *
  5 * Author: Alexandre Belloni <alexandre.belloni@bootlin.com>
  6 * Copyright (c) 2017 Microsemi Corporation
  7 */
  8
  9#include <linux/kernel.h>
 10#include <linux/module.h>
 11#include <linux/phy.h>
 12#include <linux/platform_device.h>
 13#include <linux/bitops.h>
 14#include <linux/io.h>
 15#include <linux/iopoll.h>
 16#include <linux/of_mdio.h>
 17
 18#define MSCC_MIIM_REG_STATUS		0x0
 19#define		MSCC_MIIM_STATUS_STAT_PENDING	BIT(2)
 20#define		MSCC_MIIM_STATUS_STAT_BUSY	BIT(3)
 21#define MSCC_MIIM_REG_CMD		0x8
 22#define		MSCC_MIIM_CMD_OPR_WRITE		BIT(1)
 23#define		MSCC_MIIM_CMD_OPR_READ		BIT(2)
 24#define		MSCC_MIIM_CMD_WRDATA_SHIFT	4
 25#define		MSCC_MIIM_CMD_REGAD_SHIFT	20
 26#define		MSCC_MIIM_CMD_PHYAD_SHIFT	25
 27#define		MSCC_MIIM_CMD_VLD		BIT(31)
 28#define MSCC_MIIM_REG_DATA		0xC
 29#define		MSCC_MIIM_DATA_ERROR		(BIT(16) | BIT(17))
 30
 31#define MSCC_PHY_REG_PHY_CFG	0x0
 32#define		PHY_CFG_PHY_ENA		(BIT(0) | BIT(1) | BIT(2) | BIT(3))
 33#define		PHY_CFG_PHY_COMMON_RESET BIT(4)
 34#define		PHY_CFG_PHY_RESET	(BIT(5) | BIT(6) | BIT(7) | BIT(8))
 35#define MSCC_PHY_REG_PHY_STATUS	0x4
 36
 37struct mscc_miim_dev {
 38	void __iomem *regs;
 39	void __iomem *phy_regs;
 40};
 41
 42/* When high resolution timers aren't built-in: we can't use usleep_range() as
 43 * we would sleep way too long. Use udelay() instead.
 44 */
 45#define mscc_readl_poll_timeout(addr, val, cond, delay_us, timeout_us)	\
 46({									\
 47	if (!IS_ENABLED(CONFIG_HIGH_RES_TIMERS))			\
 48		readl_poll_timeout_atomic(addr, val, cond, delay_us,	\
 49					  timeout_us);			\
 50	readl_poll_timeout(addr, val, cond, delay_us, timeout_us);	\
 51})
 52
 53static int mscc_miim_wait_ready(struct mii_bus *bus)
 54{
 55	struct mscc_miim_dev *miim = bus->priv;
 56	u32 val;
 57
 58	return mscc_readl_poll_timeout(miim->regs + MSCC_MIIM_REG_STATUS, val,
 59				       !(val & MSCC_MIIM_STATUS_STAT_BUSY), 50,
 60				       10000);
 61}
 62
 63static int mscc_miim_wait_pending(struct mii_bus *bus)
 64{
 65	struct mscc_miim_dev *miim = bus->priv;
 66	u32 val;
 67
 68	return mscc_readl_poll_timeout(miim->regs + MSCC_MIIM_REG_STATUS, val,
 69				       !(val & MSCC_MIIM_STATUS_STAT_PENDING),
 70				       50, 10000);
 71}
 72
 73static int mscc_miim_read(struct mii_bus *bus, int mii_id, int regnum)
 74{
 75	struct mscc_miim_dev *miim = bus->priv;
 76	u32 val;
 77	int ret;
 78
 79	ret = mscc_miim_wait_pending(bus);
 80	if (ret)
 81		goto out;
 82
 83	writel(MSCC_MIIM_CMD_VLD | (mii_id << MSCC_MIIM_CMD_PHYAD_SHIFT) |
 84	       (regnum << MSCC_MIIM_CMD_REGAD_SHIFT) | MSCC_MIIM_CMD_OPR_READ,
 85	       miim->regs + MSCC_MIIM_REG_CMD);
 86
 87	ret = mscc_miim_wait_ready(bus);
 88	if (ret)
 89		goto out;
 90
 91	val = readl(miim->regs + MSCC_MIIM_REG_DATA);
 92	if (val & MSCC_MIIM_DATA_ERROR) {
 93		ret = -EIO;
 94		goto out;
 95	}
 96
 97	ret = val & 0xFFFF;
 98out:
 99	return ret;
100}
101
102static int mscc_miim_write(struct mii_bus *bus, int mii_id,
103			   int regnum, u16 value)
104{
105	struct mscc_miim_dev *miim = bus->priv;
106	int ret;
107
108	ret = mscc_miim_wait_pending(bus);
109	if (ret < 0)
110		goto out;
111
112	writel(MSCC_MIIM_CMD_VLD | (mii_id << MSCC_MIIM_CMD_PHYAD_SHIFT) |
113	       (regnum << MSCC_MIIM_CMD_REGAD_SHIFT) |
114	       (value << MSCC_MIIM_CMD_WRDATA_SHIFT) |
115	       MSCC_MIIM_CMD_OPR_WRITE,
116	       miim->regs + MSCC_MIIM_REG_CMD);
117
118out:
119	return ret;
120}
121
122static int mscc_miim_reset(struct mii_bus *bus)
123{
124	struct mscc_miim_dev *miim = bus->priv;
125
126	if (miim->phy_regs) {
127		writel(0, miim->phy_regs + MSCC_PHY_REG_PHY_CFG);
128		writel(0x1ff, miim->phy_regs + MSCC_PHY_REG_PHY_CFG);
129		mdelay(500);
130	}
131
132	return 0;
133}
134
135static int mscc_miim_probe(struct platform_device *pdev)
136{
137	struct resource *res;
138	struct mii_bus *bus;
139	struct mscc_miim_dev *dev;
140	int ret;
141
142	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
143	if (!res)
144		return -ENODEV;
145
146	bus = devm_mdiobus_alloc_size(&pdev->dev, sizeof(*dev));
147	if (!bus)
148		return -ENOMEM;
149
150	bus->name = "mscc_miim";
151	bus->read = mscc_miim_read;
152	bus->write = mscc_miim_write;
153	bus->reset = mscc_miim_reset;
154	snprintf(bus->id, MII_BUS_ID_SIZE, "%s-mii", dev_name(&pdev->dev));
155	bus->parent = &pdev->dev;
156
157	dev = bus->priv;
158	dev->regs = devm_ioremap_resource(&pdev->dev, res);
159	if (IS_ERR(dev->regs)) {
160		dev_err(&pdev->dev, "Unable to map MIIM registers\n");
161		return PTR_ERR(dev->regs);
162	}
163
164	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
165	if (res) {
166		dev->phy_regs = devm_ioremap_resource(&pdev->dev, res);
167		if (IS_ERR(dev->phy_regs)) {
168			dev_err(&pdev->dev, "Unable to map internal phy registers\n");
169			return PTR_ERR(dev->phy_regs);
170		}
171	}
172
173	ret = of_mdiobus_register(bus, pdev->dev.of_node);
174	if (ret < 0) {
175		dev_err(&pdev->dev, "Cannot register MDIO bus (%d)\n", ret);
176		return ret;
177	}
178
179	platform_set_drvdata(pdev, bus);
180
181	return 0;
182}
183
184static int mscc_miim_remove(struct platform_device *pdev)
185{
186	struct mii_bus *bus = platform_get_drvdata(pdev);
187
188	mdiobus_unregister(bus);
189
190	return 0;
191}
192
193static const struct of_device_id mscc_miim_match[] = {
194	{ .compatible = "mscc,ocelot-miim" },
195	{ }
196};
197MODULE_DEVICE_TABLE(of, mscc_miim_match);
198
199static struct platform_driver mscc_miim_driver = {
200	.probe = mscc_miim_probe,
201	.remove = mscc_miim_remove,
202	.driver = {
203		.name = "mscc-miim",
204		.of_match_table = mscc_miim_match,
205	},
206};
207
208module_platform_driver(mscc_miim_driver);
209
210MODULE_DESCRIPTION("Microsemi MIIM driver");
211MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@bootlin.com>");
212MODULE_LICENSE("Dual MIT/GPL");