drivers/net/phy/mdio-mux-gpio.c

   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
  23 struct mdio_mux_gpio_state {
  24         int gpio[MDIO_MUX_GPIO_MAX_BITS];
  25         unsigned int num_gpios;
  26         void *mux_handle;
  27 };
  28
  29 static 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
  52 static 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         }
  99 err:
 100         while (n) {
 101                 n--;
 102                 gpio_free(s->gpio[n]);
 103         }
 104         devm_kfree(&pdev->dev, s);
 105         return r;
 106 }
 107
 108 static 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
 115 static 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 };
 125 MODULE_DEVICE_TABLE(of, mdio_mux_gpio_match);
 126
 127 static 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
 137 module_platform_driver(mdio_mux_gpio_driver);
 138
 139 MODULE_DESCRIPTION(DRV_DESCRIPTION);
 140 MODULE_VERSION(DRV_VERSION);
 141 MODULE_AUTHOR("David Daney");
 142 MODULE_LICENSE("GPL");