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>
15 #include <linux/of_address.h>
16 #include <linux/of_mdio.h>
17 #include <linux/module.h>
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 unsigned int iosize;
25 unsigned int mask;
26 };
27
28 /*
29 * MDIO multiplexing switch function
30 *
31 * This function is called by the mdio-mux layer when it thinks the mdio bus
32 * multiplexer needs to switch.
33 *
34 * 'current_child' is the current value of the mux register (masked via
35 * s->mask).
36 *
37 * 'desired_child' is the value of the 'reg' property of the target child MDIO
38 * node.
39 *
40 * The first time this function is called, current_child == -1.
41 *
42 * If current_child == desired_child, then the mux is already set to the
43 * correct bus.
44 */
mdio_mux_mmioreg_switch_fn(int current_child,int desired_child,void * data)45 static int mdio_mux_mmioreg_switch_fn(int current_child, int desired_child,
46 void *data)
47 {
48 struct mdio_mux_mmioreg_state *s = data;
49
50 if (current_child ^ desired_child) {
51 void __iomem *p = ioremap(s->phys, s->iosize);
52 if (!p)
53 return -ENOMEM;
54
55 switch (s->iosize) {
56 case sizeof(uint8_t): {
57 uint8_t x, y;
58
59 x = ioread8(p);
60 y = (x & ~s->mask) | desired_child;
61 if (x != y) {
62 iowrite8((x & ~s->mask) | desired_child, p);
63 pr_debug("%s: %02x -> %02x\n", __func__, x, y);
64 }
65
66 break;
67 }
68 case sizeof(uint16_t): {
69 uint16_t x, y;
70
71 x = ioread16(p);
72 y = (x & ~s->mask) | desired_child;
73 if (x != y) {
74 iowrite16((x & ~s->mask) | desired_child, p);
75 pr_debug("%s: %04x -> %04x\n", __func__, x, y);
76 }
77
78 break;
79 }
80 case sizeof(uint32_t): {
81 uint32_t x, y;
82
83 x = ioread32(p);
84 y = (x & ~s->mask) | desired_child;
85 if (x != y) {
86 iowrite32((x & ~s->mask) | desired_child, p);
87 pr_debug("%s: %08x -> %08x\n", __func__, x, y);
88 }
89
90 break;
91 }
92 }
93
94 iounmap(p);
95 }
96
97 return 0;
98 }
99
mdio_mux_mmioreg_probe(struct platform_device * pdev)100 static int mdio_mux_mmioreg_probe(struct platform_device *pdev)
101 {
102 struct device_node *np2, *np = pdev->dev.of_node;
103 struct mdio_mux_mmioreg_state *s;
104 struct resource res;
105 const __be32 *iprop;
106 int len, ret;
107
108 dev_dbg(&pdev->dev, "probing node %pOF\n", np);
109
110 s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
111 if (!s)
112 return -ENOMEM;
113
114 ret = of_address_to_resource(np, 0, &res);
115 if (ret) {
116 dev_err(&pdev->dev, "could not obtain memory map for node %pOF\n",
117 np);
118 return ret;
119 }
120 s->phys = res.start;
121
122 s->iosize = resource_size(&res);
123 if (s->iosize != sizeof(uint8_t) &&
124 s->iosize != sizeof(uint16_t) &&
125 s->iosize != sizeof(uint32_t)) {
126 dev_err(&pdev->dev, "only 8/16/32-bit registers are supported\n");
127 return -EINVAL;
128 }
129
130 iprop = of_get_property(np, "mux-mask", &len);
131 if (!iprop || len != sizeof(uint32_t)) {
132 dev_err(&pdev->dev, "missing or invalid mux-mask property\n");
133 return -ENODEV;
134 }
135 if (be32_to_cpup(iprop) >= BIT(s->iosize * 8)) {
136 dev_err(&pdev->dev, "only 8/16/32-bit registers are supported\n");
137 return -EINVAL;
138 }
139 s->mask = be32_to_cpup(iprop);
140
141 /*
142 * Verify that the 'reg' property of each child MDIO bus does not
143 * set any bits outside of the 'mask'.
144 */
145 for_each_available_child_of_node(np, np2) {
146 iprop = of_get_property(np2, "reg", &len);
147 if (!iprop || len != sizeof(uint32_t)) {
148 dev_err(&pdev->dev, "mdio-mux child node %pOF is "
149 "missing a 'reg' property\n", np2);
150 of_node_put(np2);
151 return -ENODEV;
152 }
153 if (be32_to_cpup(iprop) & ~s->mask) {
154 dev_err(&pdev->dev, "mdio-mux child node %pOF has "
155 "a 'reg' value with unmasked bits\n",
156 np2);
157 of_node_put(np2);
158 return -ENODEV;
159 }
160 }
161
162 ret = mdio_mux_init(&pdev->dev, pdev->dev.of_node,
163 mdio_mux_mmioreg_switch_fn,
164 &s->mux_handle, s, NULL);
165 if (ret) {
166 if (ret != -EPROBE_DEFER)
167 dev_err(&pdev->dev,
168 "failed to register mdio-mux bus %pOF\n", np);
169 return ret;
170 }
171
172 pdev->dev.platform_data = s;
173
174 return 0;
175 }
176
mdio_mux_mmioreg_remove(struct platform_device * pdev)177 static int mdio_mux_mmioreg_remove(struct platform_device *pdev)
178 {
179 struct mdio_mux_mmioreg_state *s = dev_get_platdata(&pdev->dev);
180
181 mdio_mux_uninit(s->mux_handle);
182
183 return 0;
184 }
185
186 static const struct of_device_id mdio_mux_mmioreg_match[] = {
187 {
188 .compatible = "mdio-mux-mmioreg",
189 },
190 {},
191 };
192 MODULE_DEVICE_TABLE(of, mdio_mux_mmioreg_match);
193
194 static struct platform_driver mdio_mux_mmioreg_driver = {
195 .driver = {
196 .name = "mdio-mux-mmioreg",
197 .of_match_table = mdio_mux_mmioreg_match,
198 },
199 .probe = mdio_mux_mmioreg_probe,
200 .remove = mdio_mux_mmioreg_remove,
201 };
202
203 module_platform_driver(mdio_mux_mmioreg_driver);
204
205 MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
206 MODULE_DESCRIPTION("Memory-mapped device MDIO MUX driver");
207 MODULE_LICENSE("GPL v2");
208
