1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Simple memory-mapped device MDIO MUX driver 4 * 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 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 *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 not 135 * 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 } 161 162 static 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 } 168 169 static const struct of_device_id mdio_mux_mmioreg_match[] = { 170 { 171 .compatible = "mdio-mux-mmioreg", 172 }, 173 {}, 174 }; 175 MODULE_DEVICE_TABLE(of, mdio_mux_mmioreg_match); 176 177 static 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 }; 185 186 module_platform_driver(mdio_mux_mmioreg_driver); 187 188 MODULE_AUTHOR("Timur Tabi <timur@freescale.com>"); 189 MODULE_DESCRIPTION("Memory-mapped device MDIO MUX driver"); 190 MODULE_LICENSE("GPL v2"); 191