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 *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 		iprop = of_get_property(np2, "reg", &len);
144 		if (!iprop || len != sizeof(uint32_t)) {
145 			dev_err(&pdev->dev, "mdio-mux child node %pOF is "
146 				"missing a 'reg' property\n", np2);
147 			of_node_put(np2);
148 			return -ENODEV;
149 		}
150 		if (be32_to_cpup(iprop) & ~s->mask) {
151 			dev_err(&pdev->dev, "mdio-mux child node %pOF has "
152 				"a 'reg' value with unmasked bits\n",
153 				np2);
154 			of_node_put(np2);
155 			return -ENODEV;
156 		}
157 	}
158 
159 	ret = mdio_mux_init(&pdev->dev, pdev->dev.of_node,
160 			    mdio_mux_mmioreg_switch_fn,
161 			    &s->mux_handle, s, NULL);
162 	if (ret)
163 		return dev_err_probe(&pdev->dev, ret,
164 				     "failed to register mdio-mux bus %pOF\n", np);
165 
166 	pdev->dev.platform_data = s;
167 
168 	return 0;
169 }
170 
171 static int mdio_mux_mmioreg_remove(struct platform_device *pdev)
172 {
173 	struct mdio_mux_mmioreg_state *s = dev_get_platdata(&pdev->dev);
174 
175 	mdio_mux_uninit(s->mux_handle);
176 
177 	return 0;
178 }
179 
180 static const struct of_device_id mdio_mux_mmioreg_match[] = {
181 	{
182 		.compatible = "mdio-mux-mmioreg",
183 	},
184 	{},
185 };
186 MODULE_DEVICE_TABLE(of, mdio_mux_mmioreg_match);
187 
188 static struct platform_driver mdio_mux_mmioreg_driver = {
189 	.driver = {
190 		.name		= "mdio-mux-mmioreg",
191 		.of_match_table = mdio_mux_mmioreg_match,
192 	},
193 	.probe		= mdio_mux_mmioreg_probe,
194 	.remove		= mdio_mux_mmioreg_remove,
195 };
196 
197 module_platform_driver(mdio_mux_mmioreg_driver);
198 
199 MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
200 MODULE_DESCRIPTION("Memory-mapped device MDIO MUX driver");
201 MODULE_LICENSE("GPL v2");
202