GNU Linux-libre 4.19.314-gnu1
[releases.git] / drivers / net / phy / mdio-mux-mmioreg.c
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  */
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
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
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");