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         unsigned int iosize;
  25         unsigned int 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 __iomem *p = ioremap(s->phys, s->iosize);
  52                 if (!p)
  53                         return -ENOMEM;
  54
  55                 switch (s->iosize) {
  56                 case sizeof(uint8_t): {
  57                         uint8_t x, y;
  58
  59                         x = ioread8(p);
  60                         y = (x & ~s->mask) | desired_child;
  61                         if (x != y) {
  62                                 iowrite8((x & ~s->mask) | desired_child, p);
  63                                 pr_debug("%s: %02x -> %02x\n", __func__, x, y);
  64                         }
  65
  66                         break;
  67                 }
  68                 case sizeof(uint16_t): {
  69                         uint16_t x, y;
  70
  71                         x = ioread16(p);
  72                         y = (x & ~s->mask) | desired_child;
  73                         if (x != y) {
  74                                 iowrite16((x & ~s->mask) | desired_child, p);
  75                                 pr_debug("%s: %04x -> %04x\n", __func__, x, y);
  76                         }
  77
  78                         break;
  79                 }
  80                 case sizeof(uint32_t): {
  81                         uint32_t x, y;
  82
  83                         x = ioread32(p);
  84                         y = (x & ~s->mask) | desired_child;
  85                         if (x != y) {
  86                                 iowrite32((x & ~s->mask) | desired_child, p);
  87                                 pr_debug("%s: %08x -> %08x\n", __func__, x, y);
  88                         }
  89
  90                         break;
  91                 }
  92                 }
  93
  94                 iounmap(p);
  95         }
  96
  97         return 0;
  98 }
  99
 100 static int mdio_mux_mmioreg_probe(struct platform_device *pdev)
 101 {
 102         struct device_node *np2, *np = pdev->dev.of_node;
 103         struct mdio_mux_mmioreg_state *s;
 104         struct resource res;
 105         const __be32 *iprop;
 106         int len, ret;
 107
 108         dev_dbg(&pdev->dev, "probing node %pOF\n", np);
 109
 110         s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
 111         if (!s)
 112                 return -ENOMEM;
 113
 114         ret = of_address_to_resource(np, 0, &res);
 115         if (ret) {
 116                 dev_err(&pdev->dev, "could not obtain memory map for node %pOF\n",
 117                         np);
 118                 return ret;
 119         }
 120         s->phys = res.start;
 121
 122         s->iosize = resource_size(&res);
 123         if (s->iosize != sizeof(uint8_t) &&
 124             s->iosize != sizeof(uint16_t) &&
 125             s->iosize != sizeof(uint32_t)) {
 126                 dev_err(&pdev->dev, "only 8/16/32-bit registers are supported\n");
 127                 return -EINVAL;
 128         }
 129
 130         iprop = of_get_property(np, "mux-mask", &len);
 131         if (!iprop || len != sizeof(uint32_t)) {
 132                 dev_err(&pdev->dev, "missing or invalid mux-mask property\n");
 133                 return -ENODEV;
 134         }
 135         if (be32_to_cpup(iprop) >= BIT(s->iosize * 8)) {
 136                 dev_err(&pdev->dev, "only 8/16/32-bit registers are supported\n");
 137                 return -EINVAL;
 138         }
 139         s->mask = be32_to_cpup(iprop);
 140
 141         /*
 142          * Verify that the 'reg' property of each child MDIO bus does not
 143          * set any bits outside of the 'mask'.
 144          */
 145         for_each_available_child_of_node(np, np2) {
 146                 iprop = of_get_property(np2, "reg", &len);
 147                 if (!iprop || len != sizeof(uint32_t)) {
 148                         dev_err(&pdev->dev, "mdio-mux child node %pOF is "
 149                                 "missing a 'reg' property\n", np2);
 150                         of_node_put(np2);
 151                         return -ENODEV;
 152                 }
 153                 if (be32_to_cpup(iprop) & ~s->mask) {
 154                         dev_err(&pdev->dev, "mdio-mux child node %pOF has "
 155                                 "a 'reg' value with unmasked bits\n",
 156                                 np2);
 157                         of_node_put(np2);
 158                         return -ENODEV;
 159                 }
 160         }
 161
 162         ret = mdio_mux_init(&pdev->dev, pdev->dev.of_node,
 163                             mdio_mux_mmioreg_switch_fn,
 164                             &s->mux_handle, s, NULL);
 165         if (ret) {
 166                 if (ret != -EPROBE_DEFER)
 167                         dev_err(&pdev->dev,
 168                                 "failed to register mdio-mux bus %pOF\n", np);
 169                 return ret;
 170         }
 171
 172         pdev->dev.platform_data = s;
 173
 174         return 0;
 175 }
 176
 177 static int mdio_mux_mmioreg_remove(struct platform_device *pdev)
 178 {
 179         struct mdio_mux_mmioreg_state *s = dev_get_platdata(&pdev->dev);
 180
 181         mdio_mux_uninit(s->mux_handle);
 182
 183         return 0;
 184 }
 185
 186 static const struct of_device_id mdio_mux_mmioreg_match[] = {
 187         {
 188                 .compatible = "mdio-mux-mmioreg",
 189         },
 190         {},
 191 };
 192 MODULE_DEVICE_TABLE(of, mdio_mux_mmioreg_match);
 193
 194 static struct platform_driver mdio_mux_mmioreg_driver = {
 195         .driver = {
 196                 .name           = "mdio-mux-mmioreg",
 197                 .of_match_table = mdio_mux_mmioreg_match,
 198         },
 199         .probe          = mdio_mux_mmioreg_probe,
 200         .remove         = mdio_mux_mmioreg_remove,
 201 };
 202
 203 module_platform_driver(mdio_mux_mmioreg_driver);
 204
 205 MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
 206 MODULE_DESCRIPTION("Memory-mapped device MDIO MUX driver");
 207 MODULE_LICENSE("GPL v2");