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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         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) {
 50                 void __iomem *p = ioremap(s->phys, 1);
 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 
 69 static int mdio_mux_mmioreg_probe(struct platform_device *pdev)
 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);
116                         of_node_put(np2);
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);
123                         of_node_put(np2);
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 
141 static int mdio_mux_mmioreg_remove(struct platform_device *pdev)
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 
150 static const struct of_device_id mdio_mux_mmioreg_match[] = {
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",
161                 .of_match_table = mdio_mux_mmioreg_match,
162         },
163         .probe          = mdio_mux_mmioreg_probe,
164         .remove         = mdio_mux_mmioreg_remove,
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");
172 

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