1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * I2C multiplexer using pinctrl API
4 *
5 * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
6 */
7
8#include <linux/i2c.h>
9#include <linux/i2c-mux.h>
10#include <linux/module.h>
11#include <linux/pinctrl/consumer.h>
12#include <linux/platform_device.h>
13#include <linux/slab.h>
14#include <linux/of.h>
15#include "../../pinctrl/core.h"
16
17struct i2c_mux_pinctrl {
18	struct pinctrl *pinctrl;
19	struct pinctrl_state *states[];
20};
21
22static int i2c_mux_pinctrl_select(struct i2c_mux_core *muxc, u32 chan)
23{
24	struct i2c_mux_pinctrl *mux = i2c_mux_priv(muxc);
25
26	return pinctrl_select_state(mux->pinctrl, mux->states[chan]);
27}
28
29static int i2c_mux_pinctrl_deselect(struct i2c_mux_core *muxc, u32 chan)
30{
31	return i2c_mux_pinctrl_select(muxc, muxc->num_adapters);
32}
33
34static struct i2c_adapter *i2c_mux_pinctrl_root_adapter(
35	struct pinctrl_state *state)
36{
37	struct i2c_adapter *root = NULL;
38	struct pinctrl_setting *setting;
39	struct i2c_adapter *pin_root;
40
41	list_for_each_entry(setting, &state->settings, node) {
42		pin_root = i2c_root_adapter(setting->pctldev->dev);
43		if (!pin_root)
44			return NULL;
45		if (!root)
46			root = pin_root;
47		else if (root != pin_root)
48			return NULL;
49	}
50
51	return root;
52}
53
54static struct i2c_adapter *i2c_mux_pinctrl_parent_adapter(struct device *dev)
55{
56	struct device_node *np = dev->of_node;
57	struct device_node *parent_np;
58	struct i2c_adapter *parent;
59
60	parent_np = of_parse_phandle(np, "i2c-parent", 0);
61	if (!parent_np) {
62		dev_err(dev, "Cannot parse i2c-parent\n");
63		return ERR_PTR(-ENODEV);
64	}
65	parent = of_get_i2c_adapter_by_node(parent_np);
66	of_node_put(parent_np);
67	if (!parent)
68		return ERR_PTR(-EPROBE_DEFER);
69
70	return parent;
71}
72
73static int i2c_mux_pinctrl_probe(struct platform_device *pdev)
74{
75	struct device *dev = &pdev->dev;
76	struct device_node *np = dev->of_node;
77	struct i2c_mux_core *muxc;
78	struct i2c_mux_pinctrl *mux;
79	struct i2c_adapter *parent;
80	struct i2c_adapter *root;
81	int num_names, i, ret;
82	const char *name;
83
84	num_names = of_property_count_strings(np, "pinctrl-names");
85	if (num_names < 0) {
86		dev_err(dev, "Cannot parse pinctrl-names: %d\n",
87			num_names);
88		return num_names;
89	}
90
91	parent = i2c_mux_pinctrl_parent_adapter(dev);
92	if (IS_ERR(parent))
93		return PTR_ERR(parent);
94
95	muxc = i2c_mux_alloc(parent, dev, num_names,
96			     struct_size(mux, states, num_names),
97			     0, i2c_mux_pinctrl_select, NULL);
98	if (!muxc) {
99		ret = -ENOMEM;
100		goto err_put_parent;
101	}
102	mux = i2c_mux_priv(muxc);
103
104	platform_set_drvdata(pdev, muxc);
105
106	mux->pinctrl = devm_pinctrl_get(dev);
107	if (IS_ERR(mux->pinctrl)) {
108		ret = PTR_ERR(mux->pinctrl);
109		dev_err(dev, "Cannot get pinctrl: %d\n", ret);
110		goto err_put_parent;
111	}
112
113	for (i = 0; i < num_names; i++) {
114		ret = of_property_read_string_index(np, "pinctrl-names", i,
115						    &name);
116		if (ret < 0) {
117			dev_err(dev, "Cannot parse pinctrl-names: %d\n", ret);
118			goto err_put_parent;
119		}
120
121		mux->states[i] = pinctrl_lookup_state(mux->pinctrl, name);
122		if (IS_ERR(mux->states[i])) {
123			ret = PTR_ERR(mux->states[i]);
124			dev_err(dev, "Cannot look up pinctrl state %s: %d\n",
125				name, ret);
126			goto err_put_parent;
127		}
128
129		if (strcmp(name, "idle"))
130			continue;
131
132		if (i != num_names - 1) {
133			dev_err(dev, "idle state must be last\n");
134			ret = -EINVAL;
135			goto err_put_parent;
136		}
137		muxc->deselect = i2c_mux_pinctrl_deselect;
138	}
139
140	root = i2c_root_adapter(&muxc->parent->dev);
141
142	muxc->mux_locked = true;
143	for (i = 0; i < num_names; i++) {
144		if (root != i2c_mux_pinctrl_root_adapter(mux->states[i])) {
145			muxc->mux_locked = false;
146			break;
147		}
148	}
149	if (muxc->mux_locked)
150		dev_info(dev, "mux-locked i2c mux\n");
151
152	/* Do not add any adapter for the idle state (if it's there at all). */
153	for (i = 0; i < num_names - !!muxc->deselect; i++) {
154		ret = i2c_mux_add_adapter(muxc, 0, i, 0);
155		if (ret)
156			goto err_del_adapter;
157	}
158
159	return 0;
160
161err_del_adapter:
162	i2c_mux_del_adapters(muxc);
163err_put_parent:
164	i2c_put_adapter(parent);
165
166	return ret;
167}
168
169static void i2c_mux_pinctrl_remove(struct platform_device *pdev)
170{
171	struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
172
173	i2c_mux_del_adapters(muxc);
174	i2c_put_adapter(muxc->parent);
175}
176
177static const struct of_device_id i2c_mux_pinctrl_of_match[] = {
178	{ .compatible = "i2c-mux-pinctrl", },
179	{},
180};
181MODULE_DEVICE_TABLE(of, i2c_mux_pinctrl_of_match);
182
183static struct platform_driver i2c_mux_pinctrl_driver = {
184	.driver	= {
185		.name	= "i2c-mux-pinctrl",
186		.of_match_table = i2c_mux_pinctrl_of_match,
187	},
188	.probe	= i2c_mux_pinctrl_probe,
189	.remove_new = i2c_mux_pinctrl_remove,
190};
191module_platform_driver(i2c_mux_pinctrl_driver);
192
193MODULE_DESCRIPTION("pinctrl-based I2C multiplexer driver");
194MODULE_AUTHOR("Stephen Warren <swarren@nvidia.com>");
195MODULE_LICENSE("GPL v2");
196MODULE_ALIAS("platform:i2c-mux-pinctrl");
197