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Timur Tabi6cc2ff82012-08-24 09:10:53 +00001/*
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>
Timur Tabi16fa9e12012-09-07 16:30:57 -050015#include <linux/of_address.h>
Timur Tabi6cc2ff82012-08-24 09:10:53 +000016#include <linux/of_mdio.h>
17#include <linux/module.h>
Timur Tabi6cc2ff82012-08-24 09:10:53 +000018#include <linux/phy.h>
19#include <linux/mdio-mux.h>
20
21struct mdio_mux_mmioreg_state {
22 void *mux_handle;
23 phys_addr_t phys;
24 uint8_t mask;
25};
26
27/*
28 * MDIO multiplexing switch function
29 *
30 * This function is called by the mdio-mux layer when it thinks the mdio bus
31 * multiplexer needs to switch.
32 *
33 * 'current_child' is the current value of the mux register (masked via
34 * s->mask).
35 *
36 * 'desired_child' is the value of the 'reg' property of the target child MDIO
37 * node.
38 *
39 * The first time this function is called, current_child == -1.
40 *
41 * If current_child == desired_child, then the mux is already set to the
42 * correct bus.
43 */
44static int mdio_mux_mmioreg_switch_fn(int current_child, int desired_child,
45 void *data)
46{
47 struct mdio_mux_mmioreg_state *s = data;
48
49 if (current_child ^ desired_child) {
Jingoo Han16dda492013-08-06 17:32:58 +090050 void __iomem *p = ioremap(s->phys, 1);
Timur Tabi6cc2ff82012-08-24 09:10:53 +000051 uint8_t x, y;
52
53 if (!p)
54 return -ENOMEM;
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 iounmap(p);
64 }
65
66 return 0;
67}
68
Bill Pemberton633d1592012-12-03 09:24:14 -050069static int mdio_mux_mmioreg_probe(struct platform_device *pdev)
Timur Tabi6cc2ff82012-08-24 09:10:53 +000070{
71 struct device_node *np2, *np = pdev->dev.of_node;
72 struct mdio_mux_mmioreg_state *s;
73 struct resource res;
74 const __be32 *iprop;
75 int len, ret;
76
77 dev_dbg(&pdev->dev, "probing node %s\n", np->full_name);
78
79 s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
80 if (!s)
81 return -ENOMEM;
82
83 ret = of_address_to_resource(np, 0, &res);
84 if (ret) {
85 dev_err(&pdev->dev, "could not obtain memory map for node %s\n",
86 np->full_name);
87 return ret;
88 }
89 s->phys = res.start;
90
91 if (resource_size(&res) != sizeof(uint8_t)) {
92 dev_err(&pdev->dev, "only 8-bit registers are supported\n");
93 return -EINVAL;
94 }
95
96 iprop = of_get_property(np, "mux-mask", &len);
97 if (!iprop || len != sizeof(uint32_t)) {
98 dev_err(&pdev->dev, "missing or invalid mux-mask property\n");
99 return -ENODEV;
100 }
101 if (be32_to_cpup(iprop) > 255) {
102 dev_err(&pdev->dev, "only 8-bit registers are supported\n");
103 return -EINVAL;
104 }
105 s->mask = be32_to_cpup(iprop);
106
107 /*
108 * Verify that the 'reg' property of each child MDIO bus does not
109 * set any bits outside of the 'mask'.
110 */
111 for_each_available_child_of_node(np, np2) {
112 iprop = of_get_property(np2, "reg", &len);
113 if (!iprop || len != sizeof(uint32_t)) {
114 dev_err(&pdev->dev, "mdio-mux child node %s is "
115 "missing a 'reg' property\n", np2->full_name);
116 return -ENODEV;
117 }
118 if (be32_to_cpup(iprop) & ~s->mask) {
119 dev_err(&pdev->dev, "mdio-mux child node %s has "
120 "a 'reg' value with unmasked bits\n",
121 np2->full_name);
122 return -ENODEV;
123 }
124 }
125
126 ret = mdio_mux_init(&pdev->dev, mdio_mux_mmioreg_switch_fn,
127 &s->mux_handle, s);
128 if (ret) {
129 dev_err(&pdev->dev, "failed to register mdio-mux bus %s\n",
130 np->full_name);
131 return ret;
132 }
133
134 pdev->dev.platform_data = s;
135
136 return 0;
137}
138
Bill Pemberton633d1592012-12-03 09:24:14 -0500139static int mdio_mux_mmioreg_remove(struct platform_device *pdev)
Timur Tabi6cc2ff82012-08-24 09:10:53 +0000140{
141 struct mdio_mux_mmioreg_state *s = dev_get_platdata(&pdev->dev);
142
143 mdio_mux_uninit(s->mux_handle);
144
145 return 0;
146}
147
148static struct of_device_id mdio_mux_mmioreg_match[] = {
149 {
150 .compatible = "mdio-mux-mmioreg",
151 },
152 {},
153};
154MODULE_DEVICE_TABLE(of, mdio_mux_mmioreg_match);
155
156static struct platform_driver mdio_mux_mmioreg_driver = {
157 .driver = {
158 .name = "mdio-mux-mmioreg",
Timur Tabi6cc2ff82012-08-24 09:10:53 +0000159 .of_match_table = mdio_mux_mmioreg_match,
160 },
161 .probe = mdio_mux_mmioreg_probe,
Bill Pemberton633d1592012-12-03 09:24:14 -0500162 .remove = mdio_mux_mmioreg_remove,
Timur Tabi6cc2ff82012-08-24 09:10:53 +0000163};
164
165module_platform_driver(mdio_mux_mmioreg_driver);
166
167MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
168MODULE_DESCRIPTION("Memory-mapped device MDIO MUX driver");
169MODULE_LICENSE("GPL v2");