1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Pinctrl based I2C DeMultiplexer
4  *
5  * Copyright (C) 2015-16 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
6  * Copyright (C) 2015-16 by Renesas Electronics Corporation
7  *
8  * See the bindings doc for DTS setup and the sysfs doc for usage information.
9  * (look for filenames containing 'i2c-demux-pinctrl' in Documentation/)
10  */
11 
12 #include <linux/i2c.h>
13 #include <linux/init.h>
14 #include <linux/module.h>
15 #include <linux/of.h>
16 #include <linux/pinctrl/consumer.h>
17 #include <linux/platform_device.h>
18 #include <linux/pm_runtime.h>
19 #include <linux/slab.h>
20 #include <linux/sysfs.h>
21 
22 struct i2c_demux_pinctrl_chan {
23 	struct device_node *parent_np;
24 	struct i2c_adapter *parent_adap;
25 	struct of_changeset chgset;
26 };
27 
28 struct i2c_demux_pinctrl_priv {
29 	int cur_chan;
30 	int num_chan;
31 	struct device *dev;
32 	const char *bus_name;
33 	struct i2c_adapter cur_adap;
34 	struct i2c_algorithm algo;
35 	struct i2c_demux_pinctrl_chan chan[];
36 };
37 
38 static int i2c_demux_master_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
39 {
40 	struct i2c_demux_pinctrl_priv *priv = adap->algo_data;
41 	struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap;
42 
43 	return __i2c_transfer(parent, msgs, num);
44 }
45 
46 static u32 i2c_demux_functionality(struct i2c_adapter *adap)
47 {
48 	struct i2c_demux_pinctrl_priv *priv = adap->algo_data;
49 	struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap;
50 
51 	return parent->algo->functionality(parent);
52 }
53 
54 static int i2c_demux_activate_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan)
55 {
56 	struct i2c_adapter *adap;
57 	struct pinctrl *p;
58 	int ret;
59 
60 	ret = of_changeset_apply(&priv->chan[new_chan].chgset);
61 	if (ret)
62 		goto err;
63 
64 	adap = of_get_i2c_adapter_by_node(priv->chan[new_chan].parent_np);
65 	if (!adap) {
66 		ret = -ENODEV;
67 		goto err_with_revert;
68 	}
69 
70 	/*
71 	 * Check if there are pinctrl states at all. Note: we cant' use
72 	 * devm_pinctrl_get_select() because we need to distinguish between
73 	 * the -ENODEV from devm_pinctrl_get() and pinctrl_lookup_state().
74 	 */
75 	p = devm_pinctrl_get(adap->dev.parent);
76 	if (IS_ERR(p)) {
77 		ret = PTR_ERR(p);
78 		/* continue if just no pinctrl states (e.g. i2c-gpio), otherwise exit */
79 		if (ret != -ENODEV)
80 			goto err_with_put;
81 	} else {
82 		/* there are states. check and use them */
83 		struct pinctrl_state *s = pinctrl_lookup_state(p, priv->bus_name);
84 
85 		if (IS_ERR(s)) {
86 			ret = PTR_ERR(s);
87 			goto err_with_put;
88 		}
89 		ret = pinctrl_select_state(p, s);
90 		if (ret < 0)
91 			goto err_with_put;
92 	}
93 
94 	priv->chan[new_chan].parent_adap = adap;
95 	priv->cur_chan = new_chan;
96 
97 	/* Now fill out current adapter structure. cur_chan must be up to date */
98 	priv->algo.master_xfer = i2c_demux_master_xfer;
99 	if (adap->algo->master_xfer_atomic)
100 		priv->algo.master_xfer_atomic = i2c_demux_master_xfer;
101 	priv->algo.functionality = i2c_demux_functionality;
102 
103 	snprintf(priv->cur_adap.name, sizeof(priv->cur_adap.name),
104 		 "i2c-demux (master i2c-%d)", i2c_adapter_id(adap));
105 	priv->cur_adap.owner = THIS_MODULE;
106 	priv->cur_adap.algo = &priv->algo;
107 	priv->cur_adap.algo_data = priv;
108 	priv->cur_adap.dev.parent = &adap->dev;
109 	priv->cur_adap.class = adap->class;
110 	priv->cur_adap.retries = adap->retries;
111 	priv->cur_adap.timeout = adap->timeout;
112 	priv->cur_adap.quirks = adap->quirks;
113 	priv->cur_adap.dev.of_node = priv->dev->of_node;
114 	ret = i2c_add_adapter(&priv->cur_adap);
115 	if (ret < 0)
116 		goto err_with_put;
117 
118 	return 0;
119 
120  err_with_put:
121 	i2c_put_adapter(adap);
122  err_with_revert:
123 	of_changeset_revert(&priv->chan[new_chan].chgset);
124  err:
125 	dev_err(priv->dev, "failed to setup demux-adapter %d (%d)\n", new_chan, ret);
126 	priv->cur_chan = -EINVAL;
127 	return ret;
128 }
129 
130 static int i2c_demux_deactivate_master(struct i2c_demux_pinctrl_priv *priv)
131 {
132 	int ret, cur = priv->cur_chan;
133 
134 	if (cur < 0)
135 		return 0;
136 
137 	i2c_del_adapter(&priv->cur_adap);
138 	i2c_put_adapter(priv->chan[cur].parent_adap);
139 
140 	ret = of_changeset_revert(&priv->chan[cur].chgset);
141 
142 	priv->chan[cur].parent_adap = NULL;
143 	priv->cur_chan = -EINVAL;
144 
145 	return ret;
146 }
147 
148 static int i2c_demux_change_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan)
149 {
150 	int ret;
151 
152 	if (new_chan == priv->cur_chan)
153 		return 0;
154 
155 	ret = i2c_demux_deactivate_master(priv);
156 	if (ret)
157 		return ret;
158 
159 	return i2c_demux_activate_master(priv, new_chan);
160 }
161 
162 static ssize_t available_masters_show(struct device *dev,
163 				      struct device_attribute *attr,
164 				      char *buf)
165 {
166 	struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
167 	int count = 0, i;
168 
169 	for (i = 0; i < priv->num_chan && count < PAGE_SIZE; i++)
170 		count += scnprintf(buf + count, PAGE_SIZE - count, "%d:%pOF%c",
171 				   i, priv->chan[i].parent_np,
172 				   i == priv->num_chan - 1 ? '\n' : ' ');
173 
174 	return count;
175 }
176 static DEVICE_ATTR_RO(available_masters);
177 
178 static ssize_t current_master_show(struct device *dev,
179 				   struct device_attribute *attr,
180 				   char *buf)
181 {
182 	struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
183 
184 	return sprintf(buf, "%d\n", priv->cur_chan);
185 }
186 
187 static ssize_t current_master_store(struct device *dev,
188 				    struct device_attribute *attr,
189 				    const char *buf, size_t count)
190 {
191 	struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
192 	unsigned int val;
193 	int ret;
194 
195 	ret = kstrtouint(buf, 0, &val);
196 	if (ret < 0)
197 		return ret;
198 
199 	if (val >= priv->num_chan)
200 		return -EINVAL;
201 
202 	ret = i2c_demux_change_master(priv, val);
203 
204 	return ret < 0 ? ret : count;
205 }
206 static DEVICE_ATTR_RW(current_master);
207 
208 static int i2c_demux_pinctrl_probe(struct platform_device *pdev)
209 {
210 	struct device_node *np = pdev->dev.of_node;
211 	struct i2c_demux_pinctrl_priv *priv;
212 	struct property *props;
213 	int num_chan, i, j, err;
214 
215 	num_chan = of_count_phandle_with_args(np, "i2c-parent", NULL);
216 	if (num_chan < 2) {
217 		dev_err(&pdev->dev, "Need at least two I2C masters to switch\n");
218 		return -EINVAL;
219 	}
220 
221 	priv = devm_kzalloc(&pdev->dev, struct_size(priv, chan, num_chan),
222 			    GFP_KERNEL);
223 
224 	props = devm_kcalloc(&pdev->dev, num_chan, sizeof(*props), GFP_KERNEL);
225 
226 	if (!priv || !props)
227 		return -ENOMEM;
228 
229 	err = of_property_read_string(np, "i2c-bus-name", &priv->bus_name);
230 	if (err)
231 		return err;
232 
233 	for (i = 0; i < num_chan; i++) {
234 		struct device_node *adap_np;
235 
236 		adap_np = of_parse_phandle(np, "i2c-parent", i);
237 		if (!adap_np) {
238 			dev_err(&pdev->dev, "can't get phandle for parent %d\n", i);
239 			err = -ENOENT;
240 			goto err_rollback;
241 		}
242 		priv->chan[i].parent_np = adap_np;
243 
244 		props[i].name = devm_kstrdup(&pdev->dev, "status", GFP_KERNEL);
245 		props[i].value = devm_kstrdup(&pdev->dev, "ok", GFP_KERNEL);
246 		if (!props[i].name || !props[i].value) {
247 			err = -ENOMEM;
248 			goto err_rollback;
249 		}
250 		props[i].length = 3;
251 
252 		of_changeset_init(&priv->chan[i].chgset);
253 		of_changeset_update_property(&priv->chan[i].chgset, adap_np, &props[i]);
254 	}
255 
256 	priv->num_chan = num_chan;
257 	priv->dev = &pdev->dev;
258 
259 	platform_set_drvdata(pdev, priv);
260 
261 	pm_runtime_no_callbacks(&pdev->dev);
262 
263 	/* switch to first parent as active master */
264 	i2c_demux_activate_master(priv, 0);
265 
266 	err = device_create_file(&pdev->dev, &dev_attr_available_masters);
267 	if (err)
268 		goto err_rollback_activation;
269 
270 	err = device_create_file(&pdev->dev, &dev_attr_current_master);
271 	if (err)
272 		goto err_rollback_available;
273 
274 	return 0;
275 
276 err_rollback_available:
277 	device_remove_file(&pdev->dev, &dev_attr_available_masters);
278 err_rollback_activation:
279 	i2c_demux_deactivate_master(priv);
280 err_rollback:
281 	for (j = 0; j < i; j++) {
282 		of_node_put(priv->chan[j].parent_np);
283 		of_changeset_destroy(&priv->chan[j].chgset);
284 	}
285 
286 	return err;
287 }
288 
289 static void i2c_demux_pinctrl_remove(struct platform_device *pdev)
290 {
291 	struct i2c_demux_pinctrl_priv *priv = platform_get_drvdata(pdev);
292 	int i;
293 
294 	device_remove_file(&pdev->dev, &dev_attr_current_master);
295 	device_remove_file(&pdev->dev, &dev_attr_available_masters);
296 
297 	i2c_demux_deactivate_master(priv);
298 
299 	for (i = 0; i < priv->num_chan; i++) {
300 		of_node_put(priv->chan[i].parent_np);
301 		of_changeset_destroy(&priv->chan[i].chgset);
302 	}
303 }
304 
305 static const struct of_device_id i2c_demux_pinctrl_of_match[] = {
306 	{ .compatible = "i2c-demux-pinctrl", },
307 	{},
308 };
309 MODULE_DEVICE_TABLE(of, i2c_demux_pinctrl_of_match);
310 
311 static struct platform_driver i2c_demux_pinctrl_driver = {
312 	.driver	= {
313 		.name = "i2c-demux-pinctrl",
314 		.of_match_table = i2c_demux_pinctrl_of_match,
315 	},
316 	.probe	= i2c_demux_pinctrl_probe,
317 	.remove_new = i2c_demux_pinctrl_remove,
318 };
319 module_platform_driver(i2c_demux_pinctrl_driver);
320 
321 MODULE_DESCRIPTION("pinctrl-based I2C demux driver");
322 MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
323 MODULE_LICENSE("GPL v2");
324 MODULE_ALIAS("platform:i2c-demux-pinctrl");
325