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 */
mdio_mux_mmioreg_switch_fn(int current_child,int desired_child,void * data)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
mdio_mux_mmioreg_probe(struct platform_device * pdev)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
mdio_mux_mmioreg_remove(struct platform_device * pdev)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