1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Broadcom BCM6368 mdiomux bus controller driver
4  *
5  * Copyright (C) 2021 Álvaro Fernández Rojas <noltari@gmail.com>
6  */
7 
8 #include <linux/delay.h>
9 #include <linux/io.h>
10 #include <linux/kernel.h>
11 #include <linux/mdio-mux.h>
12 #include <linux/module.h>
13 #include <linux/of.h>
14 #include <linux/of_platform.h>
15 #include <linux/of_mdio.h>
16 #include <linux/phy.h>
17 #include <linux/platform_device.h>
18 #include <linux/sched.h>
19 
20 #define MDIOC_REG		0x0
21 #define MDIOC_EXT_MASK		BIT(16)
22 #define MDIOC_REG_SHIFT		20
23 #define MDIOC_PHYID_SHIFT	25
24 #define MDIOC_RD_MASK		BIT(30)
25 #define MDIOC_WR_MASK		BIT(31)
26 
27 #define MDIOD_REG		0x4
28 
29 struct bcm6368_mdiomux_desc {
30 	void *mux_handle;
31 	void __iomem *base;
32 	struct device *dev;
33 	struct mii_bus *mii_bus;
34 	int ext_phy;
35 };
36 
37 static int bcm6368_mdiomux_read(struct mii_bus *bus, int phy_id, int loc)
38 {
39 	struct bcm6368_mdiomux_desc *md = bus->priv;
40 	uint32_t reg;
41 	int ret;
42 
43 	__raw_writel(0, md->base + MDIOC_REG);
44 
45 	reg = MDIOC_RD_MASK |
46 	      (phy_id << MDIOC_PHYID_SHIFT) |
47 	      (loc << MDIOC_REG_SHIFT);
48 	if (md->ext_phy)
49 		reg |= MDIOC_EXT_MASK;
50 
51 	__raw_writel(reg, md->base + MDIOC_REG);
52 	udelay(50);
53 	ret = __raw_readw(md->base + MDIOD_REG);
54 
55 	return ret;
56 }
57 
58 static int bcm6368_mdiomux_write(struct mii_bus *bus, int phy_id, int loc,
59 				 uint16_t val)
60 {
61 	struct bcm6368_mdiomux_desc *md = bus->priv;
62 	uint32_t reg;
63 
64 	__raw_writel(0, md->base + MDIOC_REG);
65 
66 	reg = MDIOC_WR_MASK |
67 	      (phy_id << MDIOC_PHYID_SHIFT) |
68 	      (loc << MDIOC_REG_SHIFT);
69 	if (md->ext_phy)
70 		reg |= MDIOC_EXT_MASK;
71 	reg |= val;
72 
73 	__raw_writel(reg, md->base + MDIOC_REG);
74 	udelay(50);
75 
76 	return 0;
77 }
78 
79 static int bcm6368_mdiomux_switch_fn(int current_child, int desired_child,
80 				     void *data)
81 {
82 	struct bcm6368_mdiomux_desc *md = data;
83 
84 	md->ext_phy = desired_child;
85 
86 	return 0;
87 }
88 
89 static int bcm6368_mdiomux_probe(struct platform_device *pdev)
90 {
91 	struct bcm6368_mdiomux_desc *md;
92 	struct mii_bus *bus;
93 	struct resource *res;
94 	int rc;
95 
96 	md = devm_kzalloc(&pdev->dev, sizeof(*md), GFP_KERNEL);
97 	if (!md)
98 		return -ENOMEM;
99 	md->dev = &pdev->dev;
100 
101 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
102 	if (!res)
103 		return -EINVAL;
104 
105 	/*
106 	 * Just ioremap, as this MDIO block is usually integrated into an
107 	 * Ethernet MAC controller register range
108 	 */
109 	md->base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
110 	if (!md->base) {
111 		dev_err(&pdev->dev, "failed to ioremap register\n");
112 		return -ENOMEM;
113 	}
114 
115 	md->mii_bus = devm_mdiobus_alloc(&pdev->dev);
116 	if (!md->mii_bus) {
117 		dev_err(&pdev->dev, "mdiomux bus alloc failed\n");
118 		return -ENOMEM;
119 	}
120 
121 	bus = md->mii_bus;
122 	bus->priv = md;
123 	bus->name = "BCM6368 MDIO mux bus";
124 	snprintf(bus->id, MII_BUS_ID_SIZE, "%s-%d", pdev->name, pdev->id);
125 	bus->parent = &pdev->dev;
126 	bus->read = bcm6368_mdiomux_read;
127 	bus->write = bcm6368_mdiomux_write;
128 	bus->phy_mask = 0x3f;
129 	bus->dev.of_node = pdev->dev.of_node;
130 
131 	rc = mdiobus_register(bus);
132 	if (rc) {
133 		dev_err(&pdev->dev, "mdiomux registration failed\n");
134 		return rc;
135 	}
136 
137 	platform_set_drvdata(pdev, md);
138 
139 	rc = mdio_mux_init(md->dev, md->dev->of_node,
140 			   bcm6368_mdiomux_switch_fn, &md->mux_handle, md,
141 			   md->mii_bus);
142 	if (rc) {
143 		dev_info(md->dev, "mdiomux initialization failed\n");
144 		goto out_register;
145 	}
146 
147 	dev_info(&pdev->dev, "Broadcom BCM6368 MDIO mux bus\n");
148 
149 	return 0;
150 
151 out_register:
152 	mdiobus_unregister(bus);
153 	return rc;
154 }
155 
156 static int bcm6368_mdiomux_remove(struct platform_device *pdev)
157 {
158 	struct bcm6368_mdiomux_desc *md = platform_get_drvdata(pdev);
159 
160 	mdio_mux_uninit(md->mux_handle);
161 	mdiobus_unregister(md->mii_bus);
162 
163 	return 0;
164 }
165 
166 static const struct of_device_id bcm6368_mdiomux_ids[] = {
167 	{ .compatible = "brcm,bcm6368-mdio-mux", },
168 	{ /* sentinel */ }
169 };
170 MODULE_DEVICE_TABLE(of, bcm6368_mdiomux_ids);
171 
172 static struct platform_driver bcm6368_mdiomux_driver = {
173 	.driver = {
174 		.name = "bcm6368-mdio-mux",
175 		.of_match_table = bcm6368_mdiomux_ids,
176 	},
177 	.probe	= bcm6368_mdiomux_probe,
178 	.remove	= bcm6368_mdiomux_remove,
179 };
180 module_platform_driver(bcm6368_mdiomux_driver);
181 
182 MODULE_AUTHOR("Álvaro Fernández Rojas <noltari@gmail.com>");
183 MODULE_DESCRIPTION("BCM6368 mdiomux bus controller driver");
184 MODULE_LICENSE("GPL v2");
185