1 /*
2  * Copyright (C) 2006-2007 PA Semi, Inc
3  *
4  * Author: Olof Johansson, PA Semi
5  *
6  * Maintained by: Olof Johansson <olof@lixom.net>
7  *
8  * Based on drivers/net/fs_enet/mii-bitbang.c.
9  *
10  * This program is free software; you can redistribute it and/or modify
11  * it under the terms of the GNU General Public License version 2 as
12  * published by the Free Software Foundation.
13  *
14  * This program is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17  * GNU General Public License for more details.
18  *
19  * You should have received a copy of the GNU General Public License
20  * along with this program; if not, write to the Free Software
21  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
22  */
23 
24 #include <linux/io.h>
25 #include <linux/module.h>
26 #include <linux/types.h>
27 #include <linux/slab.h>
28 #include <linux/sched.h>
29 #include <linux/errno.h>
30 #include <linux/ioport.h>
31 #include <linux/interrupt.h>
32 #include <linux/phy.h>
33 #include <linux/of_address.h>
34 #include <linux/of_mdio.h>
35 #include <linux/of_platform.h>
36 
37 #define DELAY 1
38 
39 static void __iomem *gpio_regs;
40 
41 struct gpio_priv {
42 	int mdc_pin;
43 	int mdio_pin;
44 };
45 
46 #define MDC_PIN(bus)	(((struct gpio_priv *)bus->priv)->mdc_pin)
47 #define MDIO_PIN(bus)	(((struct gpio_priv *)bus->priv)->mdio_pin)
48 
49 static inline void mdio_lo(struct mii_bus *bus)
50 {
51 	out_le32(gpio_regs+0x10, 1 << MDIO_PIN(bus));
52 }
53 
54 static inline void mdio_hi(struct mii_bus *bus)
55 {
56 	out_le32(gpio_regs, 1 << MDIO_PIN(bus));
57 }
58 
59 static inline void mdc_lo(struct mii_bus *bus)
60 {
61 	out_le32(gpio_regs+0x10, 1 << MDC_PIN(bus));
62 }
63 
64 static inline void mdc_hi(struct mii_bus *bus)
65 {
66 	out_le32(gpio_regs, 1 << MDC_PIN(bus));
67 }
68 
69 static inline void mdio_active(struct mii_bus *bus)
70 {
71 	out_le32(gpio_regs+0x20, (1 << MDC_PIN(bus)) | (1 << MDIO_PIN(bus)));
72 }
73 
74 static inline void mdio_tristate(struct mii_bus *bus)
75 {
76 	out_le32(gpio_regs+0x30, (1 << MDIO_PIN(bus)));
77 }
78 
79 static inline int mdio_read(struct mii_bus *bus)
80 {
81 	return !!(in_le32(gpio_regs+0x40) & (1 << MDIO_PIN(bus)));
82 }
83 
84 static void clock_out(struct mii_bus *bus, int bit)
85 {
86 	if (bit)
87 		mdio_hi(bus);
88 	else
89 		mdio_lo(bus);
90 	udelay(DELAY);
91 	mdc_hi(bus);
92 	udelay(DELAY);
93 	mdc_lo(bus);
94 }
95 
96 /* Utility to send the preamble, address, and register (common to read and write). */
97 static void bitbang_pre(struct mii_bus *bus, int read, u8 addr, u8 reg)
98 {
99 	int i;
100 
101 	/* CFE uses a really long preamble (40 bits). We'll do the same. */
102 	mdio_active(bus);
103 	for (i = 0; i < 40; i++) {
104 		clock_out(bus, 1);
105 	}
106 
107 	/* send the start bit (01) and the read opcode (10) or write (10) */
108 	clock_out(bus, 0);
109 	clock_out(bus, 1);
110 
111 	clock_out(bus, read);
112 	clock_out(bus, !read);
113 
114 	/* send the PHY address */
115 	for (i = 0; i < 5; i++) {
116 		clock_out(bus, (addr & 0x10) != 0);
117 		addr <<= 1;
118 	}
119 
120 	/* send the register address */
121 	for (i = 0; i < 5; i++) {
122 		clock_out(bus, (reg & 0x10) != 0);
123 		reg <<= 1;
124 	}
125 }
126 
127 static int gpio_mdio_read(struct mii_bus *bus, int phy_id, int location)
128 {
129 	u16 rdreg;
130 	int ret, i;
131 	u8 addr = phy_id & 0xff;
132 	u8 reg = location & 0xff;
133 
134 	bitbang_pre(bus, 1, addr, reg);
135 
136 	/* tri-state our MDIO I/O pin so we can read */
137 	mdio_tristate(bus);
138 	udelay(DELAY);
139 	mdc_hi(bus);
140 	udelay(DELAY);
141 	mdc_lo(bus);
142 
143 	/* read 16 bits of register data, MSB first */
144 	rdreg = 0;
145 	for (i = 0; i < 16; i++) {
146 		mdc_lo(bus);
147 		udelay(DELAY);
148 		mdc_hi(bus);
149 		udelay(DELAY);
150 		mdc_lo(bus);
151 		udelay(DELAY);
152 		rdreg <<= 1;
153 		rdreg |= mdio_read(bus);
154 	}
155 
156 	mdc_hi(bus);
157 	udelay(DELAY);
158 	mdc_lo(bus);
159 	udelay(DELAY);
160 
161 	ret = rdreg;
162 
163 	return ret;
164 }
165 
166 static int gpio_mdio_write(struct mii_bus *bus, int phy_id, int location, u16 val)
167 {
168 	int i;
169 
170 	u8 addr = phy_id & 0xff;
171 	u8 reg = location & 0xff;
172 	u16 value = val & 0xffff;
173 
174 	bitbang_pre(bus, 0, addr, reg);
175 
176 	/* send the turnaround (10) */
177 	mdc_lo(bus);
178 	mdio_hi(bus);
179 	udelay(DELAY);
180 	mdc_hi(bus);
181 	udelay(DELAY);
182 	mdc_lo(bus);
183 	mdio_lo(bus);
184 	udelay(DELAY);
185 	mdc_hi(bus);
186 	udelay(DELAY);
187 
188 	/* write 16 bits of register data, MSB first */
189 	for (i = 0; i < 16; i++) {
190 		mdc_lo(bus);
191 		if (value & 0x8000)
192 			mdio_hi(bus);
193 		else
194 			mdio_lo(bus);
195 		udelay(DELAY);
196 		mdc_hi(bus);
197 		udelay(DELAY);
198 		value <<= 1;
199 	}
200 
201 	/*
202 	 * Tri-state the MDIO line.
203 	 */
204 	mdio_tristate(bus);
205 	mdc_lo(bus);
206 	udelay(DELAY);
207 	mdc_hi(bus);
208 	udelay(DELAY);
209 	return 0;
210 }
211 
212 static int gpio_mdio_reset(struct mii_bus *bus)
213 {
214 	/*nothing here - dunno how to reset it*/
215 	return 0;
216 }
217 
218 
219 static int gpio_mdio_probe(struct platform_device *ofdev)
220 {
221 	struct device *dev = &ofdev->dev;
222 	struct device_node *np = ofdev->dev.of_node;
223 	struct mii_bus *new_bus;
224 	struct gpio_priv *priv;
225 	const unsigned int *prop;
226 	int err;
227 
228 	err = -ENOMEM;
229 	priv = kzalloc(sizeof(struct gpio_priv), GFP_KERNEL);
230 	if (!priv)
231 		goto out;
232 
233 	new_bus = mdiobus_alloc();
234 
235 	if (!new_bus)
236 		goto out_free_priv;
237 
238 	new_bus->name = "pasemi gpio mdio bus";
239 	new_bus->read = &gpio_mdio_read;
240 	new_bus->write = &gpio_mdio_write;
241 	new_bus->reset = &gpio_mdio_reset;
242 
243 	prop = of_get_property(np, "reg", NULL);
244 	snprintf(new_bus->id, MII_BUS_ID_SIZE, "%x", *prop);
245 	new_bus->priv = priv;
246 
247 	prop = of_get_property(np, "mdc-pin", NULL);
248 	priv->mdc_pin = *prop;
249 
250 	prop = of_get_property(np, "mdio-pin", NULL);
251 	priv->mdio_pin = *prop;
252 
253 	new_bus->parent = dev;
254 	dev_set_drvdata(dev, new_bus);
255 
256 	err = of_mdiobus_register(new_bus, np);
257 
258 	if (err != 0) {
259 		printk(KERN_ERR "%s: Cannot register as MDIO bus, err %d\n",
260 				new_bus->name, err);
261 		goto out_free_irq;
262 	}
263 
264 	return 0;
265 
266 out_free_irq:
267 	kfree(new_bus);
268 out_free_priv:
269 	kfree(priv);
270 out:
271 	return err;
272 }
273 
274 
275 static int gpio_mdio_remove(struct platform_device *dev)
276 {
277 	struct mii_bus *bus = dev_get_drvdata(&dev->dev);
278 
279 	mdiobus_unregister(bus);
280 
281 	dev_set_drvdata(&dev->dev, NULL);
282 
283 	kfree(bus->priv);
284 	bus->priv = NULL;
285 	mdiobus_free(bus);
286 
287 	return 0;
288 }
289 
290 static const struct of_device_id gpio_mdio_match[] =
291 {
292 	{
293 		.compatible      = "gpio-mdio",
294 	},
295 	{},
296 };
297 MODULE_DEVICE_TABLE(of, gpio_mdio_match);
298 
299 static struct platform_driver gpio_mdio_driver =
300 {
301 	.probe		= gpio_mdio_probe,
302 	.remove		= gpio_mdio_remove,
303 	.driver = {
304 		.name = "gpio-mdio-bitbang",
305 		.of_match_table = gpio_mdio_match,
306 	},
307 };
308 
309 static int gpio_mdio_init(void)
310 {
311 	struct device_node *np;
312 
313 	np = of_find_compatible_node(NULL, NULL, "1682m-gpio");
314 	if (!np)
315 		np = of_find_compatible_node(NULL, NULL,
316 					     "pasemi,pwrficient-gpio");
317 	if (!np)
318 		return -ENODEV;
319 	gpio_regs = of_iomap(np, 0);
320 	of_node_put(np);
321 
322 	if (!gpio_regs)
323 		return -ENODEV;
324 
325 	return platform_driver_register(&gpio_mdio_driver);
326 }
327 module_init(gpio_mdio_init);
328 
329 static void gpio_mdio_exit(void)
330 {
331 	platform_driver_unregister(&gpio_mdio_driver);
332 	if (gpio_regs)
333 		iounmap(gpio_regs);
334 }
335 module_exit(gpio_mdio_exit);
336 
337 MODULE_LICENSE("GPL");
338 MODULE_AUTHOR("Olof Johansson <olof@lixom.net>");
339 MODULE_DESCRIPTION("Driver for MDIO over GPIO on PA Semi PWRficient-based boards");
340