mdio-mux-gpio.c
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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2011, 2012 Cavium, Inc.
*/
#include <linux/platform_device.h>
#include <linux/device.h>
#include <linux/of_mdio.h>
#include <linux/module.h>
#include <linux/phy.h>
#include <linux/mdio-mux.h>
#include <linux/of_gpio.h>
#define DRV_VERSION "1.0"
#define DRV_DESCRIPTION "GPIO controlled MDIO bus multiplexer driver"
#define MDIO_MUX_GPIO_MAX_BITS 8
struct mdio_mux_gpio_state {
int gpio[MDIO_MUX_GPIO_MAX_BITS];
unsigned int num_gpios;
void *mux_handle;
};
static int mdio_mux_gpio_switch_fn(int current_child, int desired_child,
void *data)
{
int change;
unsigned int n;
struct mdio_mux_gpio_state *s = data;
if (current_child == desired_child)
return 0;
change = current_child == -1 ? -1 : current_child ^ desired_child;
for (n = 0; n < s->num_gpios; n++) {
if (change & 1)
gpio_set_value_cansleep(s->gpio[n],
(desired_child & 1) != 0);
change >>= 1;
desired_child >>= 1;
}
return 0;
}
static int mdio_mux_gpio_probe(struct platform_device *pdev)
{
enum of_gpio_flags f;
struct mdio_mux_gpio_state *s;
int num_gpios;
unsigned int n;
int r;
if (!pdev->dev.of_node)
return -ENODEV;
num_gpios = of_gpio_count(pdev->dev.of_node);
if (num_gpios <= 0 || num_gpios > MDIO_MUX_GPIO_MAX_BITS)
return -ENODEV;
s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
if (!s)
return -ENOMEM;
s->num_gpios = num_gpios;
for (n = 0; n < num_gpios; ) {
int gpio = of_get_gpio_flags(pdev->dev.of_node, n, &f);
if (gpio < 0) {
r = (gpio == -ENODEV) ? -EPROBE_DEFER : gpio;
goto err;
}
s->gpio[n] = gpio;
n++;
r = gpio_request(gpio, "mdio_mux_gpio");
if (r)
goto err;
r = gpio_direction_output(gpio, 0);
if (r)
goto err;
}
r = mdio_mux_init(&pdev->dev,
mdio_mux_gpio_switch_fn, &s->mux_handle, s);
if (r == 0) {
pdev->dev.platform_data = s;
return 0;
}
err:
while (n) {
n--;
gpio_free(s->gpio[n]);
}
return r;
}
static int mdio_mux_gpio_remove(struct platform_device *pdev)
{
struct mdio_mux_gpio_state *s = dev_get_platdata(&pdev->dev);
mdio_mux_uninit(s->mux_handle);
return 0;
}
static struct of_device_id mdio_mux_gpio_match[] = {
{
.compatible = "mdio-mux-gpio",
},
{
/* Legacy compatible property. */
.compatible = "cavium,mdio-mux-sn74cbtlv3253",
},
{},
};
MODULE_DEVICE_TABLE(of, mdio_mux_gpio_match);
static struct platform_driver mdio_mux_gpio_driver = {
.driver = {
.name = "mdio-mux-gpio",
.owner = THIS_MODULE,
.of_match_table = mdio_mux_gpio_match,
},
.probe = mdio_mux_gpio_probe,
.remove = mdio_mux_gpio_remove,
};
module_platform_driver(mdio_mux_gpio_driver);
MODULE_DESCRIPTION(DRV_DESCRIPTION);
MODULE_VERSION(DRV_VERSION);
MODULE_AUTHOR("David Daney");
MODULE_LICENSE("GPL");