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/phy.h>
  19#include <linux/mdio-mux.h>
  20
  21struct 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 */
  44static 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
  69static 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                        of_node_put(np2);
 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                        of_node_put(np2);
 124                        return -ENODEV;
 125                }
 126        }
 127
 128        ret = mdio_mux_init(&pdev->dev, mdio_mux_mmioreg_switch_fn,
 129                            &s->mux_handle, s);
 130        if (ret) {
 131                dev_err(&pdev->dev, "failed to register mdio-mux bus %s\n",
 132                        np->full_name);
 133                return ret;
 134        }
 135
 136        pdev->dev.platform_data = s;
 137
 138        return 0;
 139}
 140
 141static int mdio_mux_mmioreg_remove(struct platform_device *pdev)
 142{
 143        struct mdio_mux_mmioreg_state *s = dev_get_platdata(&pdev->dev);
 144
 145        mdio_mux_uninit(s->mux_handle);
 146
 147        return 0;
 148}
 149
 150static const struct of_device_id mdio_mux_mmioreg_match[] = {
 151        {
 152                .compatible = "mdio-mux-mmioreg",
 153        },
 154        {},
 155};
 156MODULE_DEVICE_TABLE(of, mdio_mux_mmioreg_match);
 157
 158static struct platform_driver mdio_mux_mmioreg_driver = {
 159        .driver = {
 160                .name           = "mdio-mux-mmioreg",
 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