summaryrefslogtreecommitdiffstats
path: root/drivers/i2c/muxes/i2c-demux-pinctrl.c
blob: 33ce032cb70112e9a3304f789198fbb75602a47c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
/*
 * Pinctrl based I2C DeMultiplexer
 *
 * Copyright (C) 2015-16 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
 * Copyright (C) 2015-16 by Renesas Electronics Corporation
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; version 2 of the License.
 *
 * See the bindings doc for DTS setup and the sysfs doc for usage information.
 * (look for filenames containing 'i2c-demux-pinctrl' in Documentation/)
 */

#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/sysfs.h>

struct i2c_demux_pinctrl_chan {
	struct device_node *parent_np;
	struct i2c_adapter *parent_adap;
	struct of_changeset chgset;
};

struct i2c_demux_pinctrl_priv {
	int cur_chan;
	int num_chan;
	struct device *dev;
	const char *bus_name;
	struct i2c_adapter cur_adap;
	struct i2c_algorithm algo;
	struct i2c_demux_pinctrl_chan chan[];
};

static int i2c_demux_master_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
{
	struct i2c_demux_pinctrl_priv *priv = adap->algo_data;
	struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap;

	return __i2c_transfer(parent, msgs, num);
}

static u32 i2c_demux_functionality(struct i2c_adapter *adap)
{
	struct i2c_demux_pinctrl_priv *priv = adap->algo_data;
	struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap;

	return parent->algo->functionality(parent);
}

static int i2c_demux_activate_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan)
{
	struct i2c_adapter *adap;
	struct pinctrl *p;
	int ret;

	ret = of_changeset_apply(&priv->chan[new_chan].chgset);
	if (ret)
		goto err;

	adap = of_find_i2c_adapter_by_node(priv->chan[new_chan].parent_np);
	if (!adap) {
		ret = -ENODEV;
		goto err_with_revert;
	}

	/*
	 * Check if there are pinctrl states at all. Note: we cant' use
	 * devm_pinctrl_get_select() because we need to distinguish between
	 * the -ENODEV from devm_pinctrl_get() and pinctrl_lookup_state().
	 */
	p = devm_pinctrl_get(adap->dev.parent);
	if (IS_ERR(p)) {
		ret = PTR_ERR(p);
		/* continue if just no pinctrl states (e.g. i2c-gpio), otherwise exit */
		if (ret != -ENODEV)
			goto err_with_put;
	} else {
		/* there are states. check and use them */
		struct pinctrl_state *s = pinctrl_lookup_state(p, priv->bus_name);

		if (IS_ERR(s)) {
			ret = PTR_ERR(s);
			goto err_with_put;
		}
		ret = pinctrl_select_state(p, s);
		if (ret < 0)
			goto err_with_put;
	}

	priv->chan[new_chan].parent_adap = adap;
	priv->cur_chan = new_chan;

	/* Now fill out current adapter structure. cur_chan must be up to date */
	priv->algo.master_xfer = i2c_demux_master_xfer;
	priv->algo.functionality = i2c_demux_functionality;

	snprintf(priv->cur_adap.name, sizeof(priv->cur_adap.name),
		 "i2c-demux (master i2c-%d)", i2c_adapter_id(adap));
	priv->cur_adap.owner = THIS_MODULE;
	priv->cur_adap.algo = &priv->algo;
	priv->cur_adap.algo_data = priv;
	priv->cur_adap.dev.parent = priv->dev;
	priv->cur_adap.class = adap->class;
	priv->cur_adap.retries = adap->retries;
	priv->cur_adap.timeout = adap->timeout;
	priv->cur_adap.quirks = adap->quirks;
	priv->cur_adap.dev.of_node = priv->dev->of_node;
	ret = i2c_add_adapter(&priv->cur_adap);
	if (ret < 0)
		goto err_with_put;

	return 0;

 err_with_put:
	i2c_put_adapter(adap);
 err_with_revert:
	of_changeset_revert(&priv->chan[new_chan].chgset);
 err:
	dev_err(priv->dev, "failed to setup demux-adapter %d (%d)\n", new_chan, ret);
	priv->cur_chan = -EINVAL;
	return ret;
}

static int i2c_demux_deactivate_master(struct i2c_demux_pinctrl_priv *priv)
{
	int ret, cur = priv->cur_chan;

	if (cur < 0)
		return 0;

	i2c_del_adapter(&priv->cur_adap);
	i2c_put_adapter(priv->chan[cur].parent_adap);

	ret = of_changeset_revert(&priv->chan[cur].chgset);

	priv->chan[cur].parent_adap = NULL;
	priv->cur_chan = -EINVAL;

	return ret;
}

static int i2c_demux_change_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan)
{
	int ret;

	if (new_chan == priv->cur_chan)
		return 0;

	ret = i2c_demux_deactivate_master(priv);
	if (ret)
		return ret;

	return i2c_demux_activate_master(priv, new_chan);
}

static ssize_t available_masters_show(struct device *dev,
				      struct device_attribute *attr,
				      char *buf)
{
	struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
	int count = 0, i;

	for (i = 0; i < priv->num_chan && count < PAGE_SIZE; i++)
		count += scnprintf(buf + count, PAGE_SIZE - count, "%d:%pOF%c",
				   i, priv->chan[i].parent_np,
				   i == priv->num_chan - 1 ? '\n' : ' ');

	return count;
}
static DEVICE_ATTR_RO(available_masters);

static ssize_t current_master_show(struct device *dev,
				   struct device_attribute *attr,
				   char *buf)
{
	struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);

	return sprintf(buf, "%d\n", priv->cur_chan);
}

static ssize_t current_master_store(struct device *dev,
				    struct device_attribute *attr,
				    const char *buf, size_t count)
{
	struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
	unsigned int val;
	int ret;

	ret = kstrtouint(buf, 0, &val);
	if (ret < 0)
		return ret;

	if (val >= priv->num_chan)
		return -EINVAL;

	ret = i2c_demux_change_master(priv, val);

	return ret < 0 ? ret : count;
}
static DEVICE_ATTR_RW(current_master);

static int i2c_demux_pinctrl_probe(struct platform_device *pdev)
{
	struct device_node *np = pdev->dev.of_node;
	struct i2c_demux_pinctrl_priv *priv;
	struct property *props;
	int num_chan, i, j, err;

	num_chan = of_count_phandle_with_args(np, "i2c-parent", NULL);
	if (num_chan < 2) {
		dev_err(&pdev->dev, "Need at least two I2C masters to switch\n");
		return -EINVAL;
	}

	priv = devm_kzalloc(&pdev->dev, sizeof(*priv)
			   + num_chan * sizeof(struct i2c_demux_pinctrl_chan), GFP_KERNEL);

	props = devm_kcalloc(&pdev->dev, num_chan, sizeof(*props), GFP_KERNEL);

	if (!priv || !props)
		return -ENOMEM;

	err = of_property_read_string(np, "i2c-bus-name", &priv->bus_name);
	if (err)
		return err;

	for (i = 0; i < num_chan; i++) {
		struct device_node *adap_np;

		adap_np = of_parse_phandle(np, "i2c-parent", i);
		if (!adap_np) {
			dev_err(&pdev->dev, "can't get phandle for parent %d\n", i);
			err = -ENOENT;
			goto err_rollback;
		}
		priv->chan[i].parent_np = adap_np;

		props[i].name = devm_kstrdup(&pdev->dev, "status", GFP_KERNEL);
		props[i].value = devm_kstrdup(&pdev->dev, "ok", GFP_KERNEL);
		props[i].length = 3;

		of_changeset_init(&priv->chan[i].chgset);
		of_changeset_update_property(&priv->chan[i].chgset, adap_np, &props[i]);
	}

	priv->num_chan = num_chan;
	priv->dev = &pdev->dev;

	platform_set_drvdata(pdev, priv);

	/* switch to first parent as active master */
	i2c_demux_activate_master(priv, 0);

	err = device_create_file(&pdev->dev, &dev_attr_available_masters);
	if (err)
		goto err_rollback;

	err = device_create_file(&pdev->dev, &dev_attr_current_master);
	if (err)
		goto err_rollback_available;

	return 0;

err_rollback_available:
	device_remove_file(&pdev->dev, &dev_attr_available_masters);
err_rollback:
	for (j = 0; j < i; j++) {
		of_node_put(priv->chan[j].parent_np);
		of_changeset_destroy(&priv->chan[j].chgset);
	}

	return err;
}

static int i2c_demux_pinctrl_remove(struct platform_device *pdev)
{
	struct i2c_demux_pinctrl_priv *priv = platform_get_drvdata(pdev);
	int i;

	device_remove_file(&pdev->dev, &dev_attr_current_master);
	device_remove_file(&pdev->dev, &dev_attr_available_masters);

	i2c_demux_deactivate_master(priv);

	for (i = 0; i < priv->num_chan; i++) {
		of_node_put(priv->chan[i].parent_np);
		of_changeset_destroy(&priv->chan[i].chgset);
	}

	return 0;
}

static const struct of_device_id i2c_demux_pinctrl_of_match[] = {
	{ .compatible = "i2c-demux-pinctrl", },
	{},
};
MODULE_DEVICE_TABLE(of, i2c_demux_pinctrl_of_match);

static struct platform_driver i2c_demux_pinctrl_driver = {
	.driver	= {
		.name = "i2c-demux-pinctrl",
		.of_match_table = i2c_demux_pinctrl_of_match,
	},
	.probe	= i2c_demux_pinctrl_probe,
	.remove	= i2c_demux_pinctrl_remove,
};
module_platform_driver(i2c_demux_pinctrl_driver);

MODULE_DESCRIPTION("pinctrl-based I2C demux driver");
MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:i2c-demux-pinctrl");