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/init.h>
21 #include <linux/kernel.h>
22 #include <linux/module.h>
23 #include <linux/mutex.h>
24 #include <linux/phy.h>
25 #include <linux/interrupt.h>
26 #include <linux/platform_device.h>
27 #include <linux/delay.h>
28 #include <linux/io.h>
29 #include <linux/clk.h>
30 #include <linux/of_mdio.h>
31 #include <linux/sched.h>
32 #include <linux/wait.h>
33 
34 #define MVMDIO_SMI_DATA_SHIFT              0
35 #define MVMDIO_SMI_PHY_ADDR_SHIFT          16
36 #define MVMDIO_SMI_PHY_REG_SHIFT           21
37 #define MVMDIO_SMI_READ_OPERATION          BIT(26)
38 #define MVMDIO_SMI_WRITE_OPERATION         0
39 #define MVMDIO_SMI_READ_VALID              BIT(27)
40 #define MVMDIO_SMI_BUSY                    BIT(28)
41 #define MVMDIO_ERR_INT_CAUSE		   0x007C
42 #define  MVMDIO_ERR_INT_SMI_DONE	   0x00000010
43 #define MVMDIO_ERR_INT_MASK		   0x0080
44 
45 /*
46  * SMI Timeout measurements:
47  * - Kirkwood 88F6281 (Globalscale Dreamplug): 45us to 95us (Interrupt)
48  * - Armada 370       (Globalscale Mirabox):   41us to 43us (Polled)
49  */
50 #define MVMDIO_SMI_TIMEOUT		   1000 /* 1000us = 1ms */
51 #define MVMDIO_SMI_POLL_INTERVAL_MIN	   45
52 #define MVMDIO_SMI_POLL_INTERVAL_MAX	   55
53 
54 struct orion_mdio_dev {
55 	struct mutex lock;
56 	void __iomem *regs;
57 	struct clk *clk;
58 	/*
59 	 * If we have access to the error interrupt pin (which is
60 	 * somewhat misnamed as it not only reflects internal errors
61 	 * but also reflects SMI completion), use that to wait for
62 	 * SMI access completion instead of polling the SMI busy bit.
63 	 */
64 	int err_interrupt;
65 	wait_queue_head_t smi_busy_wait;
66 };
67 
68 static int orion_mdio_smi_is_done(struct orion_mdio_dev *dev)
69 {
70 	return !(readl(dev->regs) & MVMDIO_SMI_BUSY);
71 }
72 
73 /* Wait for the SMI unit to be ready for another operation
74  */
75 static int orion_mdio_wait_ready(struct mii_bus *bus)
76 {
77 	struct orion_mdio_dev *dev = bus->priv;
78 	unsigned long timeout = usecs_to_jiffies(MVMDIO_SMI_TIMEOUT);
79 	unsigned long end = jiffies + timeout;
80 	int timedout = 0;
81 
82 	while (1) {
83 	        if (orion_mdio_smi_is_done(dev))
84 			return 0;
85 	        else if (timedout)
86 			break;
87 
88 	        if (dev->err_interrupt <= 0) {
89 			usleep_range(MVMDIO_SMI_POLL_INTERVAL_MIN,
90 				     MVMDIO_SMI_POLL_INTERVAL_MAX);
91 
92 			if (time_is_before_jiffies(end))
93 				++timedout;
94 	        } else {
95 			/* wait_event_timeout does not guarantee a delay of at
96 			 * least one whole jiffie, so timeout must be no less
97 			 * than two.
98 			 */
99 			if (timeout < 2)
100 				timeout = 2;
101 			wait_event_timeout(dev->smi_busy_wait,
102 				           orion_mdio_smi_is_done(dev),
103 				           timeout);
104 
105 			++timedout;
106 	        }
107 	}
108 
109 	dev_err(bus->parent, "Timeout: SMI busy for too long\n");
110 	return  -ETIMEDOUT;
111 }
112 
113 static int orion_mdio_read(struct mii_bus *bus, int mii_id,
114 			   int regnum)
115 {
116 	struct orion_mdio_dev *dev = bus->priv;
117 	u32 val;
118 	int ret;
119 
120 	mutex_lock(&dev->lock);
121 
122 	ret = orion_mdio_wait_ready(bus);
123 	if (ret < 0)
124 		goto out;
125 
126 	writel(((mii_id << MVMDIO_SMI_PHY_ADDR_SHIFT) |
127 		(regnum << MVMDIO_SMI_PHY_REG_SHIFT)  |
128 		MVMDIO_SMI_READ_OPERATION),
129 	       dev->regs);
130 
131 	ret = orion_mdio_wait_ready(bus);
132 	if (ret < 0)
133 		goto out;
134 
135 	val = readl(dev->regs);
136 	if (!(val & MVMDIO_SMI_READ_VALID)) {
137 		dev_err(bus->parent, "SMI bus read not valid\n");
138 		ret = -ENODEV;
139 		goto out;
140 	}
141 
142 	ret = val & 0xFFFF;
143 out:
144 	mutex_unlock(&dev->lock);
145 	return ret;
146 }
147 
148 static int orion_mdio_write(struct mii_bus *bus, int mii_id,
149 			    int regnum, u16 value)
150 {
151 	struct orion_mdio_dev *dev = bus->priv;
152 	int ret;
153 
154 	mutex_lock(&dev->lock);
155 
156 	ret = orion_mdio_wait_ready(bus);
157 	if (ret < 0)
158 		goto out;
159 
160 	writel(((mii_id << MVMDIO_SMI_PHY_ADDR_SHIFT) |
161 		(regnum << MVMDIO_SMI_PHY_REG_SHIFT)  |
162 		MVMDIO_SMI_WRITE_OPERATION            |
163 		(value << MVMDIO_SMI_DATA_SHIFT)),
164 	       dev->regs);
165 
166 out:
167 	mutex_unlock(&dev->lock);
168 	return ret;
169 }
170 
171 static int orion_mdio_reset(struct mii_bus *bus)
172 {
173 	return 0;
174 }
175 
176 static irqreturn_t orion_mdio_err_irq(int irq, void *dev_id)
177 {
178 	struct orion_mdio_dev *dev = dev_id;
179 
180 	if (readl(dev->regs + MVMDIO_ERR_INT_CAUSE) &
181 			MVMDIO_ERR_INT_SMI_DONE) {
182 		writel(~MVMDIO_ERR_INT_SMI_DONE,
183 				dev->regs + MVMDIO_ERR_INT_CAUSE);
184 		wake_up(&dev->smi_busy_wait);
185 		return IRQ_HANDLED;
186 	}
187 
188 	return IRQ_NONE;
189 }
190 
191 static int orion_mdio_probe(struct platform_device *pdev)
192 {
193 	struct resource *r;
194 	struct mii_bus *bus;
195 	struct orion_mdio_dev *dev;
196 	int i, ret;
197 
198 	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
199 	if (!r) {
200 		dev_err(&pdev->dev, "No SMI register address given\n");
201 		return -ENODEV;
202 	}
203 
204 	bus = mdiobus_alloc_size(sizeof(struct orion_mdio_dev));
205 	if (!bus) {
206 		dev_err(&pdev->dev, "Cannot allocate MDIO bus\n");
207 		return -ENOMEM;
208 	}
209 
210 	bus->name = "orion_mdio_bus";
211 	bus->read = orion_mdio_read;
212 	bus->write = orion_mdio_write;
213 	bus->reset = orion_mdio_reset;
214 	snprintf(bus->id, MII_BUS_ID_SIZE, "%s-mii",
215 		 dev_name(&pdev->dev));
216 	bus->parent = &pdev->dev;
217 
218 	bus->irq = kmalloc(sizeof(int) * PHY_MAX_ADDR, GFP_KERNEL);
219 	if (!bus->irq) {
220 		mdiobus_free(bus);
221 		return -ENOMEM;
222 	}
223 
224 	for (i = 0; i < PHY_MAX_ADDR; i++)
225 		bus->irq[i] = PHY_POLL;
226 
227 	dev = bus->priv;
228 	dev->regs = devm_ioremap(&pdev->dev, r->start, resource_size(r));
229 	if (!dev->regs) {
230 		dev_err(&pdev->dev, "Unable to remap SMI register\n");
231 		ret = -ENODEV;
232 		goto out_mdio;
233 	}
234 
235 	init_waitqueue_head(&dev->smi_busy_wait);
236 
237 	dev->clk = devm_clk_get(&pdev->dev, NULL);
238 	if (!IS_ERR(dev->clk))
239 		clk_prepare_enable(dev->clk);
240 
241 	dev->err_interrupt = platform_get_irq(pdev, 0);
242 	if (dev->err_interrupt != -ENXIO) {
243 		ret = devm_request_irq(&pdev->dev, dev->err_interrupt,
244 					orion_mdio_err_irq,
245 					IRQF_SHARED, pdev->name, dev);
246 		if (ret)
247 			goto out_mdio;
248 
249 		writel(MVMDIO_ERR_INT_SMI_DONE,
250 			dev->regs + MVMDIO_ERR_INT_MASK);
251 	}
252 
253 	mutex_init(&dev->lock);
254 
255 	if (pdev->dev.of_node)
256 		ret = of_mdiobus_register(bus, pdev->dev.of_node);
257 	else
258 		ret = mdiobus_register(bus);
259 	if (ret < 0) {
260 		dev_err(&pdev->dev, "Cannot register MDIO bus (%d)\n", ret);
261 		goto out_mdio;
262 	}
263 
264 	platform_set_drvdata(pdev, bus);
265 
266 	return 0;
267 
268 out_mdio:
269 	if (!IS_ERR(dev->clk))
270 		clk_disable_unprepare(dev->clk);
271 	kfree(bus->irq);
272 	mdiobus_free(bus);
273 	return ret;
274 }
275 
276 static int orion_mdio_remove(struct platform_device *pdev)
277 {
278 	struct mii_bus *bus = platform_get_drvdata(pdev);
279 	struct orion_mdio_dev *dev = bus->priv;
280 
281 	writel(0, dev->regs + MVMDIO_ERR_INT_MASK);
282 	mdiobus_unregister(bus);
283 	kfree(bus->irq);
284 	mdiobus_free(bus);
285 	if (!IS_ERR(dev->clk))
286 		clk_disable_unprepare(dev->clk);
287 
288 	return 0;
289 }
290 
291 static const struct of_device_id orion_mdio_match[] = {
292 	{ .compatible = "marvell,orion-mdio" },
293 	{ }
294 };
295 MODULE_DEVICE_TABLE(of, orion_mdio_match);
296 
297 static struct platform_driver orion_mdio_driver = {
298 	.probe = orion_mdio_probe,
299 	.remove = orion_mdio_remove,
300 	.driver = {
301 		.name = "orion-mdio",
302 		.of_match_table = orion_mdio_match,
303 	},
304 };
305 
306 module_platform_driver(orion_mdio_driver);
307 
308 MODULE_DESCRIPTION("Marvell MDIO interface driver");
309 MODULE_AUTHOR("Thomas Petazzoni <thomas.petazzoni@free-electrons.com>");
310 MODULE_LICENSE("GPL");
311 MODULE_ALIAS("platform:orion-mdio");
312