1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * I2C multiplexer using a single register
  4 *
  5 * Copyright 2015 Freescale Semiconductor
  6 * York Sun  <yorksun@freescale.com>
  7 */
  8
  9#include <linux/i2c.h>
 10#include <linux/i2c-mux.h>
 11#include <linux/init.h>
 12#include <linux/io.h>
 13#include <linux/module.h>
 14#include <linux/of_address.h>
 15#include <linux/platform_data/i2c-mux-reg.h>
 16#include <linux/platform_device.h>
 17#include <linux/slab.h>
 18
 19struct regmux {
 20	struct i2c_mux_reg_platform_data data;
 21};
 22
 23static int i2c_mux_reg_set(const struct regmux *mux, unsigned int chan_id)
 24{
 25	if (!mux->data.reg)
 26		return -EINVAL;
 27
 28	/*
 29	 * Write to the register, followed by a read to ensure the write is
 30	 * completed on a "posted" bus, for example PCI or write buffers.
 31	 * The endianness of reading doesn't matter and the return data
 32	 * is not used.
 33	 */
 34	switch (mux->data.reg_size) {
 35	case 4:
 36		if (mux->data.little_endian)
 37			iowrite32(chan_id, mux->data.reg);
 38		else
 39			iowrite32be(chan_id, mux->data.reg);
 40		if (!mux->data.write_only)
 41			ioread32(mux->data.reg);
 42		break;
 43	case 2:
 44		if (mux->data.little_endian)
 45			iowrite16(chan_id, mux->data.reg);
 46		else
 47			iowrite16be(chan_id, mux->data.reg);
 48		if (!mux->data.write_only)
 49			ioread16(mux->data.reg);
 50		break;
 51	case 1:
 52		iowrite8(chan_id, mux->data.reg);
 53		if (!mux->data.write_only)
 54			ioread8(mux->data.reg);
 55		break;
 56	}
 57
 58	return 0;
 59}
 60
 61static int i2c_mux_reg_select(struct i2c_mux_core *muxc, u32 chan)
 62{
 63	struct regmux *mux = i2c_mux_priv(muxc);
 64
 65	return i2c_mux_reg_set(mux, chan);
 66}
 67
 68static int i2c_mux_reg_deselect(struct i2c_mux_core *muxc, u32 chan)
 69{
 70	struct regmux *mux = i2c_mux_priv(muxc);
 71
 72	if (mux->data.idle_in_use)
 73		return i2c_mux_reg_set(mux, mux->data.idle);
 74
 75	return 0;
 76}
 77
 78#ifdef CONFIG_OF
 79static int i2c_mux_reg_probe_dt(struct regmux *mux,
 80				struct platform_device *pdev)
 81{
 82	struct device_node *np = pdev->dev.of_node;
 83	struct device_node *adapter_np, *child;
 84	struct i2c_adapter *adapter;
 85	struct resource res;
 86	unsigned *values;
 87	int i = 0;
 88
 89	if (!np)
 90		return -ENODEV;
 91
 92	adapter_np = of_parse_phandle(np, "i2c-parent", 0);
 93	if (!adapter_np) {
 94		dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
 95		return -ENODEV;
 96	}
 97	adapter = of_find_i2c_adapter_by_node(adapter_np);
 98	of_node_put(adapter_np);
 99	if (!adapter)
100		return -EPROBE_DEFER;
101
102	mux->data.parent = i2c_adapter_id(adapter);
103	put_device(&adapter->dev);
104
105	mux->data.n_values = of_get_child_count(np);
106	if (of_property_read_bool(np, "little-endian")) {
107		mux->data.little_endian = true;
108	} else if (of_property_read_bool(np, "big-endian")) {
109		mux->data.little_endian = false;
110	} else {
111#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : \
112	defined(__LITTLE_ENDIAN)
113		mux->data.little_endian = true;
114#elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : \
115	defined(__BIG_ENDIAN)
116		mux->data.little_endian = false;
117#else
118#error Endianness not defined?
119#endif
120	}
121	mux->data.write_only = of_property_read_bool(np, "write-only");
122
123	values = devm_kcalloc(&pdev->dev,
124			      mux->data.n_values, sizeof(*mux->data.values),
125			      GFP_KERNEL);
126	if (!values)
127		return -ENOMEM;
128
129	for_each_child_of_node(np, child) {
130		of_property_read_u32(child, "reg", values + i);
131		i++;
132	}
133	mux->data.values = values;
134
135	if (!of_property_read_u32(np, "idle-state", &mux->data.idle))
136		mux->data.idle_in_use = true;
137
138	/* map address from "reg" if exists */
139	if (of_address_to_resource(np, 0, &res) == 0) {
140		mux->data.reg_size = resource_size(&res);
141		mux->data.reg = devm_ioremap_resource(&pdev->dev, &res);
142		if (IS_ERR(mux->data.reg))
143			return PTR_ERR(mux->data.reg);
144	}
145
146	return 0;
147}
148#else
149static int i2c_mux_reg_probe_dt(struct regmux *mux,
150				struct platform_device *pdev)
151{
152	return 0;
153}
154#endif
155
156static int i2c_mux_reg_probe(struct platform_device *pdev)
157{
158	struct i2c_mux_core *muxc;
159	struct regmux *mux;
160	struct i2c_adapter *parent;
161	struct resource *res;
162	unsigned int class;
163	int i, ret, nr;
164
165	mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
166	if (!mux)
167		return -ENOMEM;
168
169	if (dev_get_platdata(&pdev->dev)) {
170		memcpy(&mux->data, dev_get_platdata(&pdev->dev),
171			sizeof(mux->data));
172	} else {
173		ret = i2c_mux_reg_probe_dt(mux, pdev);
174		if (ret < 0)
175			return dev_err_probe(&pdev->dev, ret,
176					     "Error parsing device tree");
177	}
178
179	parent = i2c_get_adapter(mux->data.parent);
180	if (!parent)
181		return -EPROBE_DEFER;
182
183	if (!mux->data.reg) {
184		dev_info(&pdev->dev,
185			"Register not set, using platform resource\n");
186		mux->data.reg = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
187		if (IS_ERR(mux->data.reg)) {
188			ret = PTR_ERR(mux->data.reg);
189			goto err_put_parent;
190		}
191		mux->data.reg_size = resource_size(res);
192	}
193
194	if (mux->data.reg_size != 4 && mux->data.reg_size != 2 &&
195	    mux->data.reg_size != 1) {
196		dev_err(&pdev->dev, "Invalid register size\n");
197		ret = -EINVAL;
198		goto err_put_parent;
199	}
200
201	muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values, 0, 0,
202			     i2c_mux_reg_select, NULL);
203	if (!muxc) {
204		ret = -ENOMEM;
205		goto err_put_parent;
206	}
207	muxc->priv = mux;
208
209	platform_set_drvdata(pdev, muxc);
210
211	if (mux->data.idle_in_use)
212		muxc->deselect = i2c_mux_reg_deselect;
213
214	for (i = 0; i < mux->data.n_values; i++) {
215		nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
216		class = mux->data.classes ? mux->data.classes[i] : 0;
217
218		ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class);
219		if (ret)
220			goto err_del_mux_adapters;
221	}
222
223	dev_dbg(&pdev->dev, "%d port mux on %s adapter\n",
224		 mux->data.n_values, muxc->parent->name);
225
226	return 0;
227
228err_del_mux_adapters:
229	i2c_mux_del_adapters(muxc);
230err_put_parent:
231	i2c_put_adapter(parent);
232
233	return ret;
234}
235
236static int i2c_mux_reg_remove(struct platform_device *pdev)
237{
238	struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
239
240	i2c_mux_del_adapters(muxc);
241	i2c_put_adapter(muxc->parent);
242
243	return 0;
244}
245
246static const struct of_device_id i2c_mux_reg_of_match[] = {
247	{ .compatible = "i2c-mux-reg", },
248	{},
249};
250MODULE_DEVICE_TABLE(of, i2c_mux_reg_of_match);
251
252static struct platform_driver i2c_mux_reg_driver = {
253	.probe	= i2c_mux_reg_probe,
254	.remove	= i2c_mux_reg_remove,
255	.driver	= {
256		.name	= "i2c-mux-reg",
257		.of_match_table = of_match_ptr(i2c_mux_reg_of_match),
258	},
259};
260
261module_platform_driver(i2c_mux_reg_driver);
262
263MODULE_DESCRIPTION("Register-based I2C multiplexer driver");
264MODULE_AUTHOR("York Sun <yorksun@freescale.com>");
265MODULE_LICENSE("GPL");
266MODULE_ALIAS("platform:i2c-mux-reg");