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1// SPDX-License-Identifier: GPL-2.02/*3 * Simple memory-mapped device MDIO MUX driver4 *5 * Author: Timur Tabi <timur@freescale.com>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 18struct 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 function27 *28 * This function is called by the mdio-mux layer when it thinks the mdio bus29 * multiplexer needs to switch.30 *31 * 'current_child' is the current value of the mux register (masked via32 * s->mask).33 *34 * 'desired_child' is the value of the 'reg' property of the target child MDIO35 * 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 the40 * correct bus.41 */42static 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 97static int mdio_mux_mmioreg_probe(struct platform_device *pdev)98{99 struct device_node *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 return dev_err_probe(&pdev->dev, ret,114 "could not obtain memory map for node %pOF\n", np);115 s->phys = res.start;116 117 s->iosize = resource_size(&res);118 if (s->iosize != sizeof(uint8_t) &&119 s->iosize != sizeof(uint16_t) &&120 s->iosize != sizeof(uint32_t))121 return dev_err_probe(&pdev->dev, -EINVAL,122 "only 8/16/32-bit registers are supported\n");123 124 iprop = of_get_property(np, "mux-mask", &len);125 if (!iprop || len != sizeof(uint32_t))126 return dev_err_probe(&pdev->dev, -ENODEV,127 "missing or invalid mux-mask property\n");128 if (be32_to_cpup(iprop) >= BIT(s->iosize * 8))129 return dev_err_probe(&pdev->dev, -EINVAL,130 "only 8/16/32-bit registers are supported\n");131 s->mask = be32_to_cpup(iprop);132 133 /*134 * Verify that the 'reg' property of each child MDIO bus does not135 * set any bits outside of the 'mask'.136 */137 for_each_available_child_of_node_scoped(np, np2) {138 u64 reg;139 140 if (of_property_read_reg(np2, 0, ®, NULL))141 return dev_err_probe(&pdev->dev, -ENODEV,142 "mdio-mux child node %pOF is missing a 'reg' property\n",143 np2);144 if ((u32)reg & ~s->mask)145 return dev_err_probe(&pdev->dev, -ENODEV,146 "mdio-mux child node %pOF has a 'reg' value with unmasked bits\n",147 np2);148 }149 150 ret = mdio_mux_init(&pdev->dev, pdev->dev.of_node,151 mdio_mux_mmioreg_switch_fn,152 &s->mux_handle, s, NULL);153 if (ret)154 return dev_err_probe(&pdev->dev, ret,155 "failed to register mdio-mux bus %pOF\n", np);156 157 pdev->dev.platform_data = s;158 159 return 0;160}161 162static void mdio_mux_mmioreg_remove(struct platform_device *pdev)163{164 struct mdio_mux_mmioreg_state *s = dev_get_platdata(&pdev->dev);165 166 mdio_mux_uninit(s->mux_handle);167}168 169static const struct of_device_id mdio_mux_mmioreg_match[] = {170 {171 .compatible = "mdio-mux-mmioreg",172 },173 {},174};175MODULE_DEVICE_TABLE(of, mdio_mux_mmioreg_match);176 177static struct platform_driver mdio_mux_mmioreg_driver = {178 .driver = {179 .name = "mdio-mux-mmioreg",180 .of_match_table = mdio_mux_mmioreg_match,181 },182 .probe = mdio_mux_mmioreg_probe,183 .remove_new = mdio_mux_mmioreg_remove,184};185 186module_platform_driver(mdio_mux_mmioreg_driver);187 188MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");189MODULE_DESCRIPTION("Memory-mapped device MDIO MUX driver");190MODULE_LICENSE("GPL v2");191