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Linux/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 %s\n", np->full_name);
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 %s\n",
117                         np->full_name);
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 %s is "
149                                 "missing a 'reg' property\n", np2->full_name);
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 %s has "
155                                 "a 'reg' value with unmasked bits\n",
156                                 np2->full_name);
157                         of_node_put(np2);
158                         return -ENODEV;
159                 }
160         }
161 
162         ret = mdio_mux_init(&pdev->dev, mdio_mux_mmioreg_switch_fn,
163                             &s->mux_handle, s, NULL);
164         if (ret) {
165                 dev_err(&pdev->dev, "failed to register mdio-mux bus %s\n",
166                         np->full_name);
167                 return ret;
168         }
169 
170         pdev->dev.platform_data = s;
171 
172         return 0;
173 }
174 
175 static int mdio_mux_mmioreg_remove(struct platform_device *pdev)
176 {
177         struct mdio_mux_mmioreg_state *s = dev_get_platdata(&pdev->dev);
178 
179         mdio_mux_uninit(s->mux_handle);
180 
181         return 0;
182 }
183 
184 static const struct of_device_id mdio_mux_mmioreg_match[] = {
185         {
186                 .compatible = "mdio-mux-mmioreg",
187         },
188         {},
189 };
190 MODULE_DEVICE_TABLE(of, mdio_mux_mmioreg_match);
191 
192 static struct platform_driver mdio_mux_mmioreg_driver = {
193         .driver = {
194                 .name           = "mdio-mux-mmioreg",
195                 .of_match_table = mdio_mux_mmioreg_match,
196         },
197         .probe          = mdio_mux_mmioreg_probe,
198         .remove         = mdio_mux_mmioreg_remove,
199 };
200 
201 module_platform_driver(mdio_mux_mmioreg_driver);
202 
203 MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
204 MODULE_DESCRIPTION("Memory-mapped device MDIO MUX driver");
205 MODULE_LICENSE("GPL v2");
206 

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