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6cc2ff82 TT |
1 | /* |
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> | |
16fa9e1d | 15 | #include <linux/of_address.h> |
6cc2ff82 TT |
16 | #include <linux/of_mdio.h> |
17 | #include <linux/module.h> | |
6cc2ff82 TT |
18 | #include <linux/phy.h> |
19 | #include <linux/mdio-mux.h> | |
20 | ||
21 | struct 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 | */ | |
44 | static 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) { | |
16dda493 | 50 | void __iomem *p = ioremap(s->phys, 1); |
6cc2ff82 TT |
51 | 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 | ||
633d1594 | 69 | static int mdio_mux_mmioreg_probe(struct platform_device *pdev) |
6cc2ff82 TT |
70 | { |
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); | |
02862341 | 116 | of_node_put(np2); |
6cc2ff82 TT |
117 | return -ENODEV; |
118 | } | |
119 | if (be32_to_cpup(iprop) & ~s->mask) { | |
120 | dev_err(&pdev->dev, "mdio-mux child node %s has " | |
121 | "a 'reg' value with unmasked bits\n", | |
122 | np2->full_name); | |
02862341 | 123 | of_node_put(np2); |
6cc2ff82 TT |
124 | return -ENODEV; |
125 | } | |
126 | } | |
127 | ||
128 | ret = mdio_mux_init(&pdev->dev, mdio_mux_mmioreg_switch_fn, | |
129 | &s->mux_handle, s); | |
130 | if (ret) { | |
131 | dev_err(&pdev->dev, "failed to register mdio-mux bus %s\n", | |
132 | np->full_name); | |
133 | return ret; | |
134 | } | |
135 | ||
136 | pdev->dev.platform_data = s; | |
137 | ||
138 | return 0; | |
139 | } | |
140 | ||
633d1594 | 141 | static int mdio_mux_mmioreg_remove(struct platform_device *pdev) |
6cc2ff82 TT |
142 | { |
143 | struct mdio_mux_mmioreg_state *s = dev_get_platdata(&pdev->dev); | |
144 | ||
145 | mdio_mux_uninit(s->mux_handle); | |
146 | ||
147 | return 0; | |
148 | } | |
149 | ||
d8a7dadb | 150 | static const struct of_device_id mdio_mux_mmioreg_match[] = { |
6cc2ff82 TT |
151 | { |
152 | .compatible = "mdio-mux-mmioreg", | |
153 | }, | |
154 | {}, | |
155 | }; | |
156 | MODULE_DEVICE_TABLE(of, mdio_mux_mmioreg_match); | |
157 | ||
158 | static struct platform_driver mdio_mux_mmioreg_driver = { | |
159 | .driver = { | |
160 | .name = "mdio-mux-mmioreg", | |
6cc2ff82 TT |
161 | .of_match_table = mdio_mux_mmioreg_match, |
162 | }, | |
163 | .probe = mdio_mux_mmioreg_probe, | |
633d1594 | 164 | .remove = mdio_mux_mmioreg_remove, |
6cc2ff82 TT |
165 | }; |
166 | ||
167 | module_platform_driver(mdio_mux_mmioreg_driver); | |
168 | ||
169 | MODULE_AUTHOR("Timur Tabi <timur@freescale.com>"); | |
170 | MODULE_DESCRIPTION("Memory-mapped device MDIO MUX driver"); | |
171 | MODULE_LICENSE("GPL v2"); |