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