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

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Simple memory-mapped device MDIO MUX driver
   4  *
   5  * Author: Timur Tabi <[email protected]>
   6  *
   7  * Copyright 2012 Freescale Semiconductor, Inc.
   8  */
   9
  10 #include <linux/device.h>
  11 #include <linux/mdio-mux.h>
  12 #include <linux/module.h>
  13 #include <linux/of_address.h>
  14 #include <linux/of_mdio.h>
  15 #include <linux/phy.h>
  16 #include <linux/platform_device.h>
  17
  18 struct mdio_mux_mmioreg_state {
  19         void *mux_handle;
  20         phys_addr_t phys;
  21         unsigned int iosize;
  22         unsigned int mask;
  23 };
  24
  25 /*
  26  * MDIO multiplexing switch function
  27  *
  28  * This function is called by the mdio-mux layer when it thinks the mdio bus
  29  * multiplexer needs to switch.
  30  *
  31  * 'current_child' is the current value of the mux register (masked via
  32  * s->mask).
  33  *
  34  * 'desired_child' is the value of the 'reg' property of the target child MDIO
  35  * node.
  36  *
  37  * The first time this function is called, current_child == -1.
  38  *
  39  * If current_child == desired_child, then the mux is already set to the
  40  * correct bus.
  41  */
  42 static int mdio_mux_mmioreg_switch_fn(int current_child, int desired_child,
  43                                       void *data)
  44 {
  45         struct mdio_mux_mmioreg_state *s = data;
  46
  47         if (current_child ^ desired_child) {
  48                 void __iomem *p = ioremap(s->phys, s->iosize);
  49                 if (!p)
  50                         return -ENOMEM;
  51
  52                 switch (s->iosize) {
  53                 case sizeof(uint8_t): {
  54                         uint8_t x, y;
  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                         break;
  64                 }
  65                 case sizeof(uint16_t): {
  66                         uint16_t x, y;
  67
  68                         x = ioread16(p);
  69                         y = (x & ~s->mask) | desired_child;
  70                         if (x != y) {
  71                                 iowrite16((x & ~s->mask) | desired_child, p);
  72                                 pr_debug("%s: %04x -> %04x\n", __func__, x, y);
  73                         }
  74
  75                         break;
  76                 }
  77                 case sizeof(uint32_t): {
  78                         uint32_t x, y;
  79
  80                         x = ioread32(p);
  81                         y = (x & ~s->mask) | desired_child;
  82                         if (x != y) {
  83                                 iowrite32((x & ~s->mask) | desired_child, p);
  84                                 pr_debug("%s: %08x -> %08x\n", __func__, x, y);
  85                         }
  86
  87                         break;
  88                 }
  89                 }
  90
  91                 iounmap(p);
  92         }
  93
  94         return 0;
  95 }
  96
  97 static int mdio_mux_mmioreg_probe(struct platform_device *pdev)
  98 {
  99         struct device_node *np2, *np = pdev->dev.of_node;
 100         struct mdio_mux_mmioreg_state *s;
 101         struct resource res;
 102         const __be32 *iprop;
 103         int len, ret;
 104
 105         dev_dbg(&pdev->dev, "probing node %pOF\n", np);
 106
 107         s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
 108         if (!s)
 109                 return -ENOMEM;
 110
 111         ret = of_address_to_resource(np, 0, &res);
 112         if (ret) {
 113                 dev_err(&pdev->dev, "could not obtain memory map for node %pOF\n",
 114                         np);
 115                 return ret;
 116         }
 117         s->phys = res.start;
 118
 119         s->iosize = resource_size(&res);
 120         if (s->iosize != sizeof(uint8_t) &&
 121             s->iosize != sizeof(uint16_t) &&
 122             s->iosize != sizeof(uint32_t)) {
 123                 dev_err(&pdev->dev, "only 8/16/32-bit registers are supported\n");
 124                 return -EINVAL;
 125         }
 126
 127         iprop = of_get_property(np, "mux-mask", &len);
 128         if (!iprop || len != sizeof(uint32_t)) {
 129                 dev_err(&pdev->dev, "missing or invalid mux-mask property\n");
 130                 return -ENODEV;
 131         }
 132         if (be32_to_cpup(iprop) >= BIT(s->iosize * 8)) {
 133                 dev_err(&pdev->dev, "only 8/16/32-bit registers are supported\n");
 134                 return -EINVAL;
 135         }
 136         s->mask = be32_to_cpup(iprop);
 137
 138         /*
 139          * Verify that the 'reg' property of each child MDIO bus does not
 140          * set any bits outside of the 'mask'.
 141          */
 142         for_each_available_child_of_node(np, np2) {
 143                 u64 reg;
 144
 145                 if (of_property_read_reg(np2, 0, &reg, NULL)) {
 146                         dev_err(&pdev->dev, "mdio-mux child node %pOF is "
 147                                 "missing a 'reg' property\n", np2);
 148                         of_node_put(np2);
 149                         return -ENODEV;
 150                 }
 151                 if ((u32)reg & ~s->mask) {
 152                         dev_err(&pdev->dev, "mdio-mux child node %pOF has "
 153                                 "a 'reg' value with unmasked bits\n",
 154                                 np2);
 155                         of_node_put(np2);
 156                         return -ENODEV;
 157                 }
 158         }
 159
 160         ret = mdio_mux_init(&pdev->dev, pdev->dev.of_node,
 161                             mdio_mux_mmioreg_switch_fn,
 162                             &s->mux_handle, s, NULL);
 163         if (ret)
 164                 return dev_err_probe(&pdev->dev, ret,
 165                                      "failed to register mdio-mux bus %pOF\n", np);
 166
 167         pdev->dev.platform_data = s;
 168
 169         return 0;
 170 }
 171
 172 static void mdio_mux_mmioreg_remove(struct platform_device *pdev)
 173 {
 174         struct mdio_mux_mmioreg_state *s = dev_get_platdata(&pdev->dev);
 175
 176         mdio_mux_uninit(s->mux_handle);
 177 }
 178
 179 static const struct of_device_id mdio_mux_mmioreg_match[] = {
 180         {
 181                 .compatible = "mdio-mux-mmioreg",
 182         },
 183         {},
 184 };
 185 MODULE_DEVICE_TABLE(of, mdio_mux_mmioreg_match);
 186
 187 static struct platform_driver mdio_mux_mmioreg_driver = {
 188         .driver = {
 189                 .name           = "mdio-mux-mmioreg",
 190                 .of_match_table = mdio_mux_mmioreg_match,
 191         },
 192         .probe          = mdio_mux_mmioreg_probe,
 193         .remove_new     = mdio_mux_mmioreg_remove,
 194 };
 195
 196 module_platform_driver(mdio_mux_mmioreg_driver);
 197
 198 MODULE_AUTHOR("Timur Tabi <[email protected]>");
 199 MODULE_DESCRIPTION("Memory-mapped device MDIO MUX driver");
 200 MODULE_LICENSE("GPL v2");