1/*
  2 * This file is subject to the terms and conditions of the GNU General Public
  3 * License.  See the file "COPYING" in the main directory of this archive
  4 * for more details.
  5 *
  6 * Copyright (C) 2011, 2012 Cavium, Inc.
  7 */
  8
  9#include <linux/platform_device.h>
 10#include <linux/device.h>
 11#include <linux/of_mdio.h>
 12#include <linux/module.h>
 13#include <linux/init.h>
 14#include <linux/phy.h>
 15#include <linux/mdio-mux.h>
 16#include <linux/of_gpio.h>
 17
 18#define DRV_VERSION "1.0"
 19#define DRV_DESCRIPTION "GPIO controlled MDIO bus multiplexer driver"
 20
 21#define MDIO_MUX_GPIO_MAX_BITS 8
 22
 23struct mdio_mux_gpio_state {
 24	int gpio[MDIO_MUX_GPIO_MAX_BITS];
 25	unsigned int num_gpios;
 26	void *mux_handle;
 27};
 28
 29static int mdio_mux_gpio_switch_fn(int current_child, int desired_child,
 30				   void *data)
 31{
 32	int change;
 33	unsigned int n;
 34	struct mdio_mux_gpio_state *s = data;
 35
 36	if (current_child == desired_child)
 37		return 0;
 38
 39	change = current_child == -1 ? -1 : current_child ^ desired_child;
 40
 41	for (n = 0; n < s->num_gpios; n++) {
 42		if (change & 1)
 43			gpio_set_value_cansleep(s->gpio[n],
 44						(desired_child & 1) != 0);
 45		change >>= 1;
 46		desired_child >>= 1;
 47	}
 48
 49	return 0;
 50}
 51
 52static int __devinit mdio_mux_gpio_probe(struct platform_device *pdev)
 53{
 54	enum of_gpio_flags f;
 55	struct mdio_mux_gpio_state *s;
 56	unsigned int num_gpios;
 57	unsigned int n;
 58	int r;
 59
 60	if (!pdev->dev.of_node)
 61		return -ENODEV;
 62
 63	num_gpios = of_gpio_count(pdev->dev.of_node);
 64	if (num_gpios == 0 || num_gpios > MDIO_MUX_GPIO_MAX_BITS)
 65		return -ENODEV;
 66
 67	s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
 68	if (!s)
 69		return -ENOMEM;
 70
 71	s->num_gpios = num_gpios;
 72
 73	for (n = 0; n < num_gpios; ) {
 74		int gpio = of_get_gpio_flags(pdev->dev.of_node, n, &f);
 75		if (gpio < 0) {
 76			r = (gpio == -ENODEV) ? -EPROBE_DEFER : gpio;
 77			goto err;
 78		}
 79		s->gpio[n] = gpio;
 80
 81		n++;
 82
 83		r = gpio_request(gpio, "mdio_mux_gpio");
 84		if (r)
 85			goto err;
 86
 87		r = gpio_direction_output(gpio, 0);
 88		if (r)
 89			goto err;
 90	}
 91
 92	r = mdio_mux_init(&pdev->dev,
 93			  mdio_mux_gpio_switch_fn, &s->mux_handle, s);
 94
 95	if (r == 0) {
 96		pdev->dev.platform_data = s;
 97		return 0;
 98	}
 99err:
100	while (n) {
101		n--;
102		gpio_free(s->gpio[n]);
103	}
104	devm_kfree(&pdev->dev, s);
105	return r;
106}
107
108static int __devexit mdio_mux_gpio_remove(struct platform_device *pdev)
109{
110	struct mdio_mux_gpio_state *s = pdev->dev.platform_data;
111	mdio_mux_uninit(s->mux_handle);
112	return 0;
113}
114
115static struct of_device_id mdio_mux_gpio_match[] = {
116	{
117		.compatible = "mdio-mux-gpio",
118	},
119	{
120		/* Legacy compatible property. */
121		.compatible = "cavium,mdio-mux-sn74cbtlv3253",
122	},
123	{},
124};
125MODULE_DEVICE_TABLE(of, mdio_mux_gpio_match);
126
127static struct platform_driver mdio_mux_gpio_driver = {
128	.driver = {
129		.name		= "mdio-mux-gpio",
130		.owner		= THIS_MODULE,
131		.of_match_table = mdio_mux_gpio_match,
132	},
133	.probe		= mdio_mux_gpio_probe,
134	.remove		= __devexit_p(mdio_mux_gpio_remove),
135};
136
137module_platform_driver(mdio_mux_gpio_driver);
138
139MODULE_DESCRIPTION(DRV_DESCRIPTION);
140MODULE_VERSION(DRV_VERSION);
141MODULE_AUTHOR("David Daney");
142MODULE_LICENSE("GPL");