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 
17 struct i2c_mux_pinctrl {
18 	struct pinctrl *pinctrl;
19 	struct pinctrl_state *states[];
20 };
21 
22 static 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 
29 static 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 
34 static 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 
54 static 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_find_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 
73 static 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 
161 err_del_adapter:
162 	i2c_mux_del_adapters(muxc);
163 err_put_parent:
164 	i2c_put_adapter(parent);
165 
166 	return ret;
167 }
168 
169 static int 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 	return 0;
177 }
178 
179 static const struct of_device_id i2c_mux_pinctrl_of_match[] = {
180 	{ .compatible = "i2c-mux-pinctrl", },
181 	{},
182 };
183 MODULE_DEVICE_TABLE(of, i2c_mux_pinctrl_of_match);
184 
185 static struct platform_driver i2c_mux_pinctrl_driver = {
186 	.driver	= {
187 		.name	= "i2c-mux-pinctrl",
188 		.of_match_table = i2c_mux_pinctrl_of_match,
189 	},
190 	.probe	= i2c_mux_pinctrl_probe,
191 	.remove	= i2c_mux_pinctrl_remove,
192 };
193 module_platform_driver(i2c_mux_pinctrl_driver);
194 
195 MODULE_DESCRIPTION("pinctrl-based I2C multiplexer driver");
196 MODULE_AUTHOR("Stephen Warren <swarren@nvidia.com>");
197 MODULE_LICENSE("GPL v2");
198 MODULE_ALIAS("platform:i2c-mux-pinctrl");
199