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
 21struct 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 */
 45static 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
100static 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
177static 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
186static const struct of_device_id mdio_mux_mmioreg_match[] = {
187	{
188		.compatible = "mdio-mux-mmioreg",
189	},
190	{},
191};
192MODULE_DEVICE_TABLE(of, mdio_mux_mmioreg_match);
193
194static 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
203module_platform_driver(mdio_mux_mmioreg_driver);
204
205MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
206MODULE_DESCRIPTION("Memory-mapped device MDIO MUX driver");
207MODULE_LICENSE("GPL v2");