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
i2c_mux_pinctrl_select(struct i2c_mux_core * muxc,u32 chan)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
i2c_mux_pinctrl_deselect(struct i2c_mux_core * muxc,u32 chan)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
i2c_mux_pinctrl_root_adapter(struct pinctrl_state * state)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
i2c_mux_pinctrl_parent_adapter(struct device * dev)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_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
i2c_mux_pinctrl_probe(struct platform_device * pdev)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
i2c_mux_pinctrl_remove(struct platform_device * pdev)169 static 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
177 static const struct of_device_id i2c_mux_pinctrl_of_match[] = {
178 { .compatible = "i2c-mux-pinctrl", },
179 {},
180 };
181 MODULE_DEVICE_TABLE(of, i2c_mux_pinctrl_of_match);
182
183 static 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 };
191 module_platform_driver(i2c_mux_pinctrl_driver);
192
193 MODULE_DESCRIPTION("pinctrl-based I2C multiplexer driver");
194 MODULE_AUTHOR("Stephen Warren <swarren@nvidia.com>");
195 MODULE_LICENSE("GPL v2");
196 MODULE_ALIAS("platform:i2c-mux-pinctrl");
197