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/phy.h>
  19 #include <linux/mdio-mux.h>
  20
  21 struct mdio_mux_mmioreg_state {
  22         void *mux_handle;
  23         phys_addr_t phys;
  24         uint8_t mask;
  25 };
  26
  27 /*
  28  * MDIO multiplexing switch function
  29  *
  30  * This function is called by the mdio-mux layer when it thinks the mdio bus
  31  * multiplexer needs to switch.
  32  *
  33  * 'current_child' is the current value of the mux register (masked via
  34  * s->mask).
  35  *
  36  * 'desired_child' is the value of the 'reg' property of the target child MDIO
  37  * node.
  38  *
  39  * The first time this function is called, current_child == -1.
  40  *
  41  * If current_child == desired_child, then the mux is already set to the
  42  * correct bus.
  43  */
  44 static int mdio_mux_mmioreg_switch_fn(int current_child, int desired_child,
  45                                       void *data)
  46 {
  47         struct mdio_mux_mmioreg_state *s = data;
  48
  49         if (current_child ^ desired_child) {
  50                 void __iomem *p = ioremap(s->phys, 1);
  51                 uint8_t x, y;
  52
  53                 if (!p)
  54                         return -ENOMEM;
  55
  56                 x = ioread8(p);
  57                 y = (x & ~s->mask) | desired_child;
  58                 if (x != y) {
  59                         iowrite8((x & ~s->mask) | desired_child, p);
  60                         pr_debug("%s: %02x -> %02x\n", __func__, x, y);
  61                 }
  62
  63                 iounmap(p);
  64         }
  65
  66         return 0;
  67 }
  68
  69 static int mdio_mux_mmioreg_probe(struct platform_device *pdev)
  70 {
  71         struct device_node *np2, *np = pdev->dev.of_node;
  72         struct mdio_mux_mmioreg_state *s;
  73         struct resource res;
  74         const __be32 *iprop;
  75         int len, ret;
  76
  77         dev_dbg(&pdev->dev, "probing node %s\n", np->full_name);
  78
  79         s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
  80         if (!s)
  81                 return -ENOMEM;
  82
  83         ret = of_address_to_resource(np, 0, &res);
  84         if (ret) {
  85                 dev_err(&pdev->dev, "could not obtain memory map for node %s\n",
  86                         np->full_name);
  87                 return ret;
  88         }
  89         s->phys = res.start;
  90
  91         if (resource_size(&res) != sizeof(uint8_t)) {
  92                 dev_err(&pdev->dev, "only 8-bit registers are supported\n");
  93                 return -EINVAL;
  94         }
  95
  96         iprop = of_get_property(np, "mux-mask", &len);
  97         if (!iprop || len != sizeof(uint32_t)) {
  98                 dev_err(&pdev->dev, "missing or invalid mux-mask property\n");
  99                 return -ENODEV;
 100         }
 101         if (be32_to_cpup(iprop) > 255) {
 102                 dev_err(&pdev->dev, "only 8-bit registers are supported\n");
 103                 return -EINVAL;
 104         }
 105         s->mask = be32_to_cpup(iprop);
 106
 107         /*
 108          * Verify that the 'reg' property of each child MDIO bus does not
 109          * set any bits outside of the 'mask'.
 110          */
 111         for_each_available_child_of_node(np, np2) {
 112                 iprop = of_get_property(np2, "reg", &len);
 113                 if (!iprop || len != sizeof(uint32_t)) {
 114                         dev_err(&pdev->dev, "mdio-mux child node %s is "
 115                                 "missing a 'reg' property\n", np2->full_name);
 116                         return -ENODEV;
 117                 }
 118                 if (be32_to_cpup(iprop) & ~s->mask) {
 119                         dev_err(&pdev->dev, "mdio-mux child node %s has "
 120                                 "a 'reg' value with unmasked bits\n",
 121                                 np2->full_name);
 122                         return -ENODEV;
 123                 }
 124         }
 125
 126         ret = mdio_mux_init(&pdev->dev, mdio_mux_mmioreg_switch_fn,
 127                             &s->mux_handle, s);
 128         if (ret) {
 129                 dev_err(&pdev->dev, "failed to register mdio-mux bus %s\n",
 130                         np->full_name);
 131                 return ret;
 132         }
 133
 134         pdev->dev.platform_data = s;
 135
 136         return 0;
 137 }
 138
 139 static int mdio_mux_mmioreg_remove(struct platform_device *pdev)
 140 {
 141         struct mdio_mux_mmioreg_state *s = dev_get_platdata(&pdev->dev);
 142
 143         mdio_mux_uninit(s->mux_handle);
 144
 145         return 0;
 146 }
 147
 148 static struct of_device_id mdio_mux_mmioreg_match[] = {
 149         {
 150                 .compatible = "mdio-mux-mmioreg",
 151         },
 152         {},
 153 };
 154 MODULE_DEVICE_TABLE(of, mdio_mux_mmioreg_match);
 155
 156 static struct platform_driver mdio_mux_mmioreg_driver = {
 157         .driver = {
 158                 .name           = "mdio-mux-mmioreg",
 159                 .of_match_table = mdio_mux_mmioreg_match,
 160         },
 161         .probe          = mdio_mux_mmioreg_probe,
 162         .remove         = mdio_mux_mmioreg_remove,
 163 };
 164
 165 module_platform_driver(mdio_mux_mmioreg_driver);
 166
 167 MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
 168 MODULE_DESCRIPTION("Memory-mapped device MDIO MUX driver");
 169 MODULE_LICENSE("GPL v2");