LXR linux/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
  22struct 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 */
  45static 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
  70static 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
 140static 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
 149static struct of_device_id mdio_mux_mmioreg_match[] = {
 150        {
 151                .compatible = "mdio-mux-mmioreg",
 152        },
 153        {},
 154};
 155MODULE_DEVICE_TABLE(of, mdio_mux_mmioreg_match);
 156
 157static 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
 167module_platform_driver(mdio_mux_mmioreg_driver);
 168
 169MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
 170MODULE_DESCRIPTION("Memory-mapped device MDIO MUX driver");
 171MODULE_LICENSE("GPL v2");
 172