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[] __counted_by(num_chan);
36 };
37
i2c_demux_master_xfer(struct i2c_adapter * adap,struct i2c_msg msgs[],int num)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
i2c_demux_functionality(struct i2c_adapter * adap)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
i2c_demux_activate_master(struct i2c_demux_pinctrl_priv * priv,u32 new_chan)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
i2c_demux_deactivate_master(struct i2c_demux_pinctrl_priv * priv)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
i2c_demux_change_master(struct i2c_demux_pinctrl_priv * priv,u32 new_chan)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
available_masters_show(struct device * dev,struct device_attribute * attr,char * buf)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 += sysfs_emit_at(buf, 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
current_master_show(struct device * dev,struct device_attribute * attr,char * buf)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
current_master_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)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
i2c_demux_pinctrl_probe(struct platform_device * pdev)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 priv->num_chan = num_chan;
230
231 err = of_property_read_string(np, "i2c-bus-name", &priv->bus_name);
232 if (err)
233 return err;
234
235 for (i = 0; i < num_chan; i++) {
236 struct device_node *adap_np;
237
238 adap_np = of_parse_phandle(np, "i2c-parent", i);
239 if (!adap_np) {
240 dev_err(&pdev->dev, "can't get phandle for parent %d\n", i);
241 err = -ENOENT;
242 goto err_rollback;
243 }
244 priv->chan[i].parent_np = adap_np;
245
246 props[i].name = devm_kstrdup(&pdev->dev, "status", GFP_KERNEL);
247 props[i].value = devm_kstrdup(&pdev->dev, "ok", GFP_KERNEL);
248 if (!props[i].name || !props[i].value) {
249 err = -ENOMEM;
250 goto err_rollback;
251 }
252 props[i].length = 3;
253
254 of_changeset_init(&priv->chan[i].chgset);
255 of_changeset_update_property(&priv->chan[i].chgset, adap_np, &props[i]);
256 }
257
258 priv->dev = &pdev->dev;
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
i2c_demux_pinctrl_remove(struct platform_device * pdev)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