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

   1 /*
   2  * Simple memory-mapped device MDIO MUX driver
   3  *
   4  * Author: Timur Tabi <timur@freescale.com>
   5  *
   6  * Copyright 2012 Freescale Semiconductor, Inc.
   7  *
   8  * This file is licensed under the terms of the GNU General Public License
   9  * version 2.  This program is licensed "as is" without any warranty of any
  10  * kind, whether express or implied.
  11  */
  12
  13 #include <linux/platform_device.h>
  14 #include <linux/device.h>
  15 #include <linux/of_address.h>
  16 #include <linux/of_mdio.h>
  17 #include <linux/module.h>
  18 #include <linux/init.h>
  19 #include <linux/phy.h>
  20 #include <linux/mdio-mux.h>
  21
  22 struct mdio_mux_mmioreg_state {
  23         void *mux_handle;
  24         phys_addr_t phys;
  25         uint8_t mask;
  26 };
  27
  28 /*
  29  * MDIO multiplexing switch function
  30  *
  31  * This function is called by the mdio-mux layer when it thinks the mdio bus
  32  * multiplexer needs to switch.
  33  *
  34  * 'current_child' is the current value of the mux register (masked via
  35  * s->mask).
  36  *
  37  * 'desired_child' is the value of the 'reg' property of the target child MDIO
  38  * node.
  39  *
  40  * The first time this function is called, current_child == -1.
  41  *
  42  * If current_child == desired_child, then the mux is already set to the
  43  * correct bus.
  44  */
  45 static int mdio_mux_mmioreg_switch_fn(int current_child, int desired_child,
  46                                       void *data)
  47 {
  48         struct mdio_mux_mmioreg_state *s = data;
  49
  50         if (current_child ^ desired_child) {
  51                 void *p = ioremap(s->phys, 1);
  52                 uint8_t x, y;
  53
  54                 if (!p)
  55                         return -ENOMEM;
  56
  57                 x = ioread8(p);
  58                 y = (x & ~s->mask) | desired_child;
  59                 if (x != y) {
  60                         iowrite8((x & ~s->mask) | desired_child, p);
  61                         pr_debug("%s: %02x -> %02x\n", __func__, x, y);
  62                 }
  63
  64                 iounmap(p);
  65         }
  66
  67         return 0;
  68 }
  69
  70 static int mdio_mux_mmioreg_probe(struct platform_device *pdev)
  71 {
  72         struct device_node *np2, *np = pdev->dev.of_node;
  73         struct mdio_mux_mmioreg_state *s;
  74         struct resource res;
  75         const __be32 *iprop;
  76         int len, ret;
  77
  78         dev_dbg(&pdev->dev, "probing node %s\n", np->full_name);
  79
  80         s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
  81         if (!s)
  82                 return -ENOMEM;
  83
  84         ret = of_address_to_resource(np, 0, &res);
  85         if (ret) {
  86                 dev_err(&pdev->dev, "could not obtain memory map for node %s\n",
  87                         np->full_name);
  88                 return ret;
  89         }
  90         s->phys = res.start;
  91
  92         if (resource_size(&res) != sizeof(uint8_t)) {
  93                 dev_err(&pdev->dev, "only 8-bit registers are supported\n");
  94                 return -EINVAL;
  95         }
  96
  97         iprop = of_get_property(np, "mux-mask", &len);
  98         if (!iprop || len != sizeof(uint32_t)) {
  99                 dev_err(&pdev->dev, "missing or invalid mux-mask property\n");
 100                 return -ENODEV;
 101         }
 102         if (be32_to_cpup(iprop) > 255) {
 103                 dev_err(&pdev->dev, "only 8-bit registers are supported\n");
 104                 return -EINVAL;
 105         }
 106         s->mask = be32_to_cpup(iprop);
 107
 108         /*
 109          * Verify that the 'reg' property of each child MDIO bus does not
 110          * set any bits outside of the 'mask'.
 111          */
 112         for_each_available_child_of_node(np, np2) {
 113                 iprop = of_get_property(np2, "reg", &len);
 114                 if (!iprop || len != sizeof(uint32_t)) {
 115                         dev_err(&pdev->dev, "mdio-mux child node %s is "
 116                                 "missing a 'reg' property\n", np2->full_name);
 117                         return -ENODEV;
 118                 }
 119                 if (be32_to_cpup(iprop) & ~s->mask) {
 120                         dev_err(&pdev->dev, "mdio-mux child node %s has "
 121                                 "a 'reg' value with unmasked bits\n",
 122                                 np2->full_name);
 123                         return -ENODEV;
 124                 }
 125         }
 126
 127         ret = mdio_mux_init(&pdev->dev, mdio_mux_mmioreg_switch_fn,
 128                             &s->mux_handle, s);
 129         if (ret) {
 130                 dev_err(&pdev->dev, "failed to register mdio-mux bus %s\n",
 131                         np->full_name);
 132                 return ret;
 133         }
 134
 135         pdev->dev.platform_data = s;
 136
 137         return 0;
 138 }
 139
 140 static int mdio_mux_mmioreg_remove(struct platform_device *pdev)
 141 {
 142         struct mdio_mux_mmioreg_state *s = dev_get_platdata(&pdev->dev);
 143
 144         mdio_mux_uninit(s->mux_handle);
 145
 146         return 0;
 147 }
 148
 149 static struct of_device_id mdio_mux_mmioreg_match[] = {
 150         {
 151                 .compatible = "mdio-mux-mmioreg",
 152         },
 153         {},
 154 };
 155 MODULE_DEVICE_TABLE(of, mdio_mux_mmioreg_match);
 156
 157 static struct platform_driver mdio_mux_mmioreg_driver = {
 158         .driver = {
 159                 .name           = "mdio-mux-mmioreg",
 160                 .owner          = THIS_MODULE,
 161                 .of_match_table = mdio_mux_mmioreg_match,
 162         },
 163         .probe          = mdio_mux_mmioreg_probe,
 164         .remove         = mdio_mux_mmioreg_remove,
 165 };
 166
 167 module_platform_driver(mdio_mux_mmioreg_driver);
 168
 169 MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
 170 MODULE_DESCRIPTION("Memory-mapped device MDIO MUX driver");
 171 MODULE_LICENSE("GPL v2");