1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Driver for MMIO-Mapped MDIO devices. Some IPs expose internal PHYs or PCS
3 * within the MMIO-mapped area
4 *
5 * Copyright (C) 2023 Maxime Chevallier <maxime.chevallier@bootlin.com>
6 */
7#include <linux/bitfield.h>
8#include <linux/delay.h>
9#include <linux/mdio.h>
10#include <linux/module.h>
11#include <linux/of.h>
12#include <linux/of_mdio.h>
13#include <linux/phy.h>
14#include <linux/platform_device.h>
15#include <linux/regmap.h>
16#include <linux/mdio/mdio-regmap.h>
17
18#define DRV_NAME "mdio-regmap"
19
20struct mdio_regmap_priv {
21	struct regmap *regmap;
22	u8 valid_addr;
23};
24
25static int mdio_regmap_read_c22(struct mii_bus *bus, int addr, int regnum)
26{
27	struct mdio_regmap_priv *ctx = bus->priv;
28	unsigned int val;
29	int ret;
30
31	if (ctx->valid_addr != addr)
32		return -ENODEV;
33
34	ret = regmap_read(ctx->regmap, regnum, &val);
35	if (ret < 0)
36		return ret;
37
38	return val;
39}
40
41static int mdio_regmap_write_c22(struct mii_bus *bus, int addr, int regnum,
42				 u16 val)
43{
44	struct mdio_regmap_priv *ctx = bus->priv;
45
46	if (ctx->valid_addr != addr)
47		return -ENODEV;
48
49	return regmap_write(ctx->regmap, regnum, val);
50}
51
52struct mii_bus *devm_mdio_regmap_register(struct device *dev,
53					  const struct mdio_regmap_config *config)
54{
55	struct mdio_regmap_priv *mr;
56	struct mii_bus *mii;
57	int rc;
58
59	if (!config->parent)
60		return ERR_PTR(-EINVAL);
61
62	mii = devm_mdiobus_alloc_size(config->parent, sizeof(*mr));
63	if (!mii)
64		return ERR_PTR(-ENOMEM);
65
66	mr = mii->priv;
67	mr->regmap = config->regmap;
68	mr->valid_addr = config->valid_addr;
69
70	mii->name = DRV_NAME;
71	strscpy(mii->id, config->name, MII_BUS_ID_SIZE);
72	mii->parent = config->parent;
73	mii->read = mdio_regmap_read_c22;
74	mii->write = mdio_regmap_write_c22;
75
76	if (config->autoscan)
77		mii->phy_mask = ~BIT(config->valid_addr);
78	else
79		mii->phy_mask = ~0;
80
81	rc = devm_mdiobus_register(dev, mii);
82	if (rc) {
83		dev_err(config->parent, "Cannot register MDIO bus![%s] (%d)\n", mii->id, rc);
84		return ERR_PTR(rc);
85	}
86
87	return mii;
88}
89EXPORT_SYMBOL_GPL(devm_mdio_regmap_register);
90
91MODULE_DESCRIPTION("MDIO API over regmap");
92MODULE_AUTHOR("Maxime Chevallier <maxime.chevallier@bootlin.com>");
93MODULE_LICENSE("GPL");
94