1/*
2 * Driver for the MDIO interface of Marvell network interfaces.
3 *
4 * Since the MDIO interface of Marvell network interfaces is shared
5 * between all network interfaces, having a single driver allows to
6 * handle concurrent accesses properly (you may have four Ethernet
7 * ports, but they in fact share the same SMI interface to access
8 * the MDIO bus). This driver is currently used by the mvneta and
9 * mv643xx_eth drivers.
10 *
11 * Copyright (C) 2012 Marvell
12 *
13 * Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
14 *
15 * This file is licensed under the terms of the GNU General Public
16 * License version 2. This program is licensed "as is" without any
17 * warranty of any kind, whether express or implied.
18 */
19
20#include <linux/kernel.h>
21#include <linux/module.h>
22#include <linux/mutex.h>
23#include <linux/phy.h>
24#include <linux/interrupt.h>
25#include <linux/platform_device.h>
26#include <linux/delay.h>
27#include <linux/io.h>
28#include <linux/clk.h>
29#include <linux/of_mdio.h>
30#include <linux/sched.h>
31#include <linux/wait.h>
32
33#define MVMDIO_SMI_DATA_SHIFT              0
34#define MVMDIO_SMI_PHY_ADDR_SHIFT          16
35#define MVMDIO_SMI_PHY_REG_SHIFT           21
36#define MVMDIO_SMI_READ_OPERATION          BIT(26)
37#define MVMDIO_SMI_WRITE_OPERATION         0
38#define MVMDIO_SMI_READ_VALID              BIT(27)
39#define MVMDIO_SMI_BUSY                    BIT(28)
40#define MVMDIO_ERR_INT_CAUSE		   0x007C
41#define  MVMDIO_ERR_INT_SMI_DONE	   0x00000010
42#define MVMDIO_ERR_INT_MASK		   0x0080
43
44/*
45 * SMI Timeout measurements:
46 * - Kirkwood 88F6281 (Globalscale Dreamplug): 45us to 95us (Interrupt)
47 * - Armada 370       (Globalscale Mirabox):   41us to 43us (Polled)
48 */
49#define MVMDIO_SMI_TIMEOUT		   1000 /* 1000us = 1ms */
50#define MVMDIO_SMI_POLL_INTERVAL_MIN	   45
51#define MVMDIO_SMI_POLL_INTERVAL_MAX	   55
52
53struct orion_mdio_dev {
54	struct mutex lock;
55	void __iomem *regs;
56	struct clk *clk;
57	/*
58	 * If we have access to the error interrupt pin (which is
59	 * somewhat misnamed as it not only reflects internal errors
60	 * but also reflects SMI completion), use that to wait for
61	 * SMI access completion instead of polling the SMI busy bit.
62	 */
63	int err_interrupt;
64	wait_queue_head_t smi_busy_wait;
65};
66
67static int orion_mdio_smi_is_done(struct orion_mdio_dev *dev)
68{
69	return !(readl(dev->regs) & MVMDIO_SMI_BUSY);
70}
71
72/* Wait for the SMI unit to be ready for another operation
73 */
74static int orion_mdio_wait_ready(struct mii_bus *bus)
75{
76	struct orion_mdio_dev *dev = bus->priv;
77	unsigned long timeout = usecs_to_jiffies(MVMDIO_SMI_TIMEOUT);
78	unsigned long end = jiffies + timeout;
79	int timedout = 0;
80
81	while (1) {
82	        if (orion_mdio_smi_is_done(dev))
83			return 0;
84	        else if (timedout)
85			break;
86
87	        if (dev->err_interrupt <= 0) {
88			usleep_range(MVMDIO_SMI_POLL_INTERVAL_MIN,
89				     MVMDIO_SMI_POLL_INTERVAL_MAX);
90
91			if (time_is_before_jiffies(end))
92				++timedout;
93	        } else {
94			/* wait_event_timeout does not guarantee a delay of at
95			 * least one whole jiffie, so timeout must be no less
96			 * than two.
97			 */
98			if (timeout < 2)
99				timeout = 2;
100			wait_event_timeout(dev->smi_busy_wait,
101				           orion_mdio_smi_is_done(dev),
102				           timeout);
103
104			++timedout;
105	        }
106	}
107
108	dev_err(bus->parent, "Timeout: SMI busy for too long\n");
109	return  -ETIMEDOUT;
110}
111
112static int orion_mdio_read(struct mii_bus *bus, int mii_id,
113			   int regnum)
114{
115	struct orion_mdio_dev *dev = bus->priv;
116	u32 val;
117	int ret;
118
119	mutex_lock(&dev->lock);
120
121	ret = orion_mdio_wait_ready(bus);
122	if (ret < 0)
123		goto out;
124
125	writel(((mii_id << MVMDIO_SMI_PHY_ADDR_SHIFT) |
126		(regnum << MVMDIO_SMI_PHY_REG_SHIFT)  |
127		MVMDIO_SMI_READ_OPERATION),
128	       dev->regs);
129
130	ret = orion_mdio_wait_ready(bus);
131	if (ret < 0)
132		goto out;
133
134	val = readl(dev->regs);
135	if (!(val & MVMDIO_SMI_READ_VALID)) {
136		dev_err(bus->parent, "SMI bus read not valid\n");
137		ret = -ENODEV;
138		goto out;
139	}
140
141	ret = val & 0xFFFF;
142out:
143	mutex_unlock(&dev->lock);
144	return ret;
145}
146
147static int orion_mdio_write(struct mii_bus *bus, int mii_id,
148			    int regnum, u16 value)
149{
150	struct orion_mdio_dev *dev = bus->priv;
151	int ret;
152
153	mutex_lock(&dev->lock);
154
155	ret = orion_mdio_wait_ready(bus);
156	if (ret < 0)
157		goto out;
158
159	writel(((mii_id << MVMDIO_SMI_PHY_ADDR_SHIFT) |
160		(regnum << MVMDIO_SMI_PHY_REG_SHIFT)  |
161		MVMDIO_SMI_WRITE_OPERATION            |
162		(value << MVMDIO_SMI_DATA_SHIFT)),
163	       dev->regs);
164
165out:
166	mutex_unlock(&dev->lock);
167	return ret;
168}
169
170static irqreturn_t orion_mdio_err_irq(int irq, void *dev_id)
171{
172	struct orion_mdio_dev *dev = dev_id;
173
174	if (readl(dev->regs + MVMDIO_ERR_INT_CAUSE) &
175			MVMDIO_ERR_INT_SMI_DONE) {
176		writel(~MVMDIO_ERR_INT_SMI_DONE,
177				dev->regs + MVMDIO_ERR_INT_CAUSE);
178		wake_up(&dev->smi_busy_wait);
179		return IRQ_HANDLED;
180	}
181
182	return IRQ_NONE;
183}
184
185static int orion_mdio_probe(struct platform_device *pdev)
186{
187	struct resource *r;
188	struct mii_bus *bus;
189	struct orion_mdio_dev *dev;
190	int i, ret;
191
192	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
193	if (!r) {
194		dev_err(&pdev->dev, "No SMI register address given\n");
195		return -ENODEV;
196	}
197
198	bus = devm_mdiobus_alloc_size(&pdev->dev,
199				      sizeof(struct orion_mdio_dev));
200	if (!bus)
201		return -ENOMEM;
202
203	bus->name = "orion_mdio_bus";
204	bus->read = orion_mdio_read;
205	bus->write = orion_mdio_write;
206	snprintf(bus->id, MII_BUS_ID_SIZE, "%s-mii",
207		 dev_name(&pdev->dev));
208	bus->parent = &pdev->dev;
209
210	bus->irq = devm_kmalloc_array(&pdev->dev, PHY_MAX_ADDR, sizeof(int),
211				      GFP_KERNEL);
212	if (!bus->irq)
213		return -ENOMEM;
214
215	for (i = 0; i < PHY_MAX_ADDR; i++)
216		bus->irq[i] = PHY_POLL;
217
218	dev = bus->priv;
219	dev->regs = devm_ioremap(&pdev->dev, r->start, resource_size(r));
220	if (!dev->regs) {
221		dev_err(&pdev->dev, "Unable to remap SMI register\n");
222		ret = -ENODEV;
223		goto out_mdio;
224	}
225
226	init_waitqueue_head(&dev->smi_busy_wait);
227
228	dev->clk = devm_clk_get(&pdev->dev, NULL);
229	if (!IS_ERR(dev->clk))
230		clk_prepare_enable(dev->clk);
231
232	dev->err_interrupt = platform_get_irq(pdev, 0);
233	if (dev->err_interrupt > 0) {
234		ret = devm_request_irq(&pdev->dev, dev->err_interrupt,
235					orion_mdio_err_irq,
236					IRQF_SHARED, pdev->name, dev);
237		if (ret)
238			goto out_mdio;
239
240		writel(MVMDIO_ERR_INT_SMI_DONE,
241			dev->regs + MVMDIO_ERR_INT_MASK);
242
243	} else if (dev->err_interrupt == -EPROBE_DEFER) {
244		return -EPROBE_DEFER;
245	}
246
247	mutex_init(&dev->lock);
248
249	if (pdev->dev.of_node)
250		ret = of_mdiobus_register(bus, pdev->dev.of_node);
251	else
252		ret = mdiobus_register(bus);
253	if (ret < 0) {
254		dev_err(&pdev->dev, "Cannot register MDIO bus (%d)\n", ret);
255		goto out_mdio;
256	}
257
258	platform_set_drvdata(pdev, bus);
259
260	return 0;
261
262out_mdio:
263	if (!IS_ERR(dev->clk))
264		clk_disable_unprepare(dev->clk);
265	return ret;
266}
267
268static int orion_mdio_remove(struct platform_device *pdev)
269{
270	struct mii_bus *bus = platform_get_drvdata(pdev);
271	struct orion_mdio_dev *dev = bus->priv;
272
273	writel(0, dev->regs + MVMDIO_ERR_INT_MASK);
274	mdiobus_unregister(bus);
275	if (!IS_ERR(dev->clk))
276		clk_disable_unprepare(dev->clk);
277
278	return 0;
279}
280
281static const struct of_device_id orion_mdio_match[] = {
282	{ .compatible = "marvell,orion-mdio" },
283	{ }
284};
285MODULE_DEVICE_TABLE(of, orion_mdio_match);
286
287static struct platform_driver orion_mdio_driver = {
288	.probe = orion_mdio_probe,
289	.remove = orion_mdio_remove,
290	.driver = {
291		.name = "orion-mdio",
292		.of_match_table = orion_mdio_match,
293	},
294};
295
296module_platform_driver(orion_mdio_driver);
297
298MODULE_DESCRIPTION("Marvell MDIO interface driver");
299MODULE_AUTHOR("Thomas Petazzoni <thomas.petazzoni@free-electrons.com>");
300MODULE_LICENSE("GPL");
301MODULE_ALIAS("platform:orion-mdio");
302