2 * Pinctrl based I2C DeMultiplexer
4 * Copyright (C) 2015-16 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
5 * Copyright (C) 2015-16 by Renesas Electronics Corporation
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License as published by the
9 * Free Software Foundation; version 2 of the License.
11 * See the bindings doc for DTS setup and the sysfs doc for usage information.
12 * (look for filenames containing 'i2c-demux-pinctrl' in Documentation/)
15 #include <linux/i2c.h>
16 #include <linux/init.h>
17 #include <linux/module.h>
19 #include <linux/pinctrl/consumer.h>
20 #include <linux/platform_device.h>
21 #include <linux/slab.h>
22 #include <linux/sysfs.h>
24 struct i2c_demux_pinctrl_chan {
25 struct device_node *parent_np;
26 struct i2c_adapter *parent_adap;
27 struct of_changeset chgset;
30 struct i2c_demux_pinctrl_priv {
35 struct i2c_adapter cur_adap;
36 struct i2c_algorithm algo;
37 struct i2c_demux_pinctrl_chan chan[];
40 static int i2c_demux_master_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
42 struct i2c_demux_pinctrl_priv *priv = adap->algo_data;
43 struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap;
45 return __i2c_transfer(parent, msgs, num);
48 static u32 i2c_demux_functionality(struct i2c_adapter *adap)
50 struct i2c_demux_pinctrl_priv *priv = adap->algo_data;
51 struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap;
53 return parent->algo->functionality(parent);
56 static int i2c_demux_activate_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan)
58 struct i2c_adapter *adap;
62 ret = of_changeset_apply(&priv->chan[new_chan].chgset);
66 adap = of_find_i2c_adapter_by_node(priv->chan[new_chan].parent_np);
72 p = devm_pinctrl_get_select(adap->dev.parent, priv->bus_name);
78 priv->chan[new_chan].parent_adap = adap;
79 priv->cur_chan = new_chan;
81 /* Now fill out current adapter structure. cur_chan must be up to date */
82 priv->algo.master_xfer = i2c_demux_master_xfer;
83 priv->algo.functionality = i2c_demux_functionality;
85 snprintf(priv->cur_adap.name, sizeof(priv->cur_adap.name),
86 "i2c-demux (master i2c-%d)", i2c_adapter_id(adap));
87 priv->cur_adap.owner = THIS_MODULE;
88 priv->cur_adap.algo = &priv->algo;
89 priv->cur_adap.algo_data = priv;
90 priv->cur_adap.dev.parent = priv->dev;
91 priv->cur_adap.class = adap->class;
92 priv->cur_adap.retries = adap->retries;
93 priv->cur_adap.timeout = adap->timeout;
94 priv->cur_adap.quirks = adap->quirks;
95 priv->cur_adap.dev.of_node = priv->dev->of_node;
96 ret = i2c_add_adapter(&priv->cur_adap);
103 i2c_put_adapter(adap);
105 of_changeset_revert(&priv->chan[new_chan].chgset);
107 dev_err(priv->dev, "failed to setup demux-adapter %d (%d)\n", new_chan, ret);
108 priv->cur_chan = -EINVAL;
112 static int i2c_demux_deactivate_master(struct i2c_demux_pinctrl_priv *priv)
114 int ret, cur = priv->cur_chan;
119 i2c_del_adapter(&priv->cur_adap);
120 i2c_put_adapter(priv->chan[cur].parent_adap);
122 ret = of_changeset_revert(&priv->chan[cur].chgset);
124 priv->chan[cur].parent_adap = NULL;
125 priv->cur_chan = -EINVAL;
130 static int i2c_demux_change_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan)
134 if (new_chan == priv->cur_chan)
137 ret = i2c_demux_deactivate_master(priv);
141 return i2c_demux_activate_master(priv, new_chan);
144 static ssize_t available_masters_show(struct device *dev,
145 struct device_attribute *attr,
148 struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
151 for (i = 0; i < priv->num_chan && count < PAGE_SIZE; i++)
152 count += scnprintf(buf + count, PAGE_SIZE - count, "%d:%s%c",
153 i, priv->chan[i].parent_np->full_name,
154 i == priv->num_chan - 1 ? '\n' : ' ');
158 static DEVICE_ATTR_RO(available_masters);
160 static ssize_t current_master_show(struct device *dev,
161 struct device_attribute *attr,
164 struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
166 return sprintf(buf, "%d\n", priv->cur_chan);
169 static ssize_t current_master_store(struct device *dev,
170 struct device_attribute *attr,
171 const char *buf, size_t count)
173 struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
177 ret = kstrtouint(buf, 0, &val);
181 if (val >= priv->num_chan)
184 ret = i2c_demux_change_master(priv, val);
186 return ret < 0 ? ret : count;
188 static DEVICE_ATTR_RW(current_master);
190 static int i2c_demux_pinctrl_probe(struct platform_device *pdev)
192 struct device_node *np = pdev->dev.of_node;
193 struct i2c_demux_pinctrl_priv *priv;
194 struct property *props;
195 int num_chan, i, j, err;
197 num_chan = of_count_phandle_with_args(np, "i2c-parent", NULL);
199 dev_err(&pdev->dev, "Need at least two I2C masters to switch\n");
203 priv = devm_kzalloc(&pdev->dev, sizeof(*priv)
204 + num_chan * sizeof(struct i2c_demux_pinctrl_chan), GFP_KERNEL);
206 props = devm_kcalloc(&pdev->dev, num_chan, sizeof(*props), GFP_KERNEL);
211 err = of_property_read_string(np, "i2c-bus-name", &priv->bus_name);
215 for (i = 0; i < num_chan; i++) {
216 struct device_node *adap_np;
218 adap_np = of_parse_phandle(np, "i2c-parent", i);
220 dev_err(&pdev->dev, "can't get phandle for parent %d\n", i);
224 priv->chan[i].parent_np = adap_np;
226 props[i].name = devm_kstrdup(&pdev->dev, "status", GFP_KERNEL);
227 props[i].value = devm_kstrdup(&pdev->dev, "ok", GFP_KERNEL);
230 of_changeset_init(&priv->chan[i].chgset);
231 of_changeset_update_property(&priv->chan[i].chgset, adap_np, &props[i]);
234 priv->num_chan = num_chan;
235 priv->dev = &pdev->dev;
237 platform_set_drvdata(pdev, priv);
239 /* switch to first parent as active master */
240 i2c_demux_activate_master(priv, 0);
242 err = device_create_file(&pdev->dev, &dev_attr_available_masters);
246 err = device_create_file(&pdev->dev, &dev_attr_current_master);
248 goto err_rollback_available;
252 err_rollback_available:
253 device_remove_file(&pdev->dev, &dev_attr_available_masters);
255 for (j = 0; j < i; j++) {
256 of_node_put(priv->chan[j].parent_np);
257 of_changeset_destroy(&priv->chan[j].chgset);
263 static int i2c_demux_pinctrl_remove(struct platform_device *pdev)
265 struct i2c_demux_pinctrl_priv *priv = platform_get_drvdata(pdev);
268 device_remove_file(&pdev->dev, &dev_attr_current_master);
269 device_remove_file(&pdev->dev, &dev_attr_available_masters);
271 i2c_demux_deactivate_master(priv);
273 for (i = 0; i < priv->num_chan; i++) {
274 of_node_put(priv->chan[i].parent_np);
275 of_changeset_destroy(&priv->chan[i].chgset);
281 static const struct of_device_id i2c_demux_pinctrl_of_match[] = {
282 { .compatible = "i2c-demux-pinctrl", },
285 MODULE_DEVICE_TABLE(of, i2c_demux_pinctrl_of_match);
287 static struct platform_driver i2c_demux_pinctrl_driver = {
289 .name = "i2c-demux-pinctrl",
290 .of_match_table = i2c_demux_pinctrl_of_match,
292 .probe = i2c_demux_pinctrl_probe,
293 .remove = i2c_demux_pinctrl_remove,
295 module_platform_driver(i2c_demux_pinctrl_driver);
297 MODULE_DESCRIPTION("pinctrl-based I2C demux driver");
298 MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
299 MODULE_LICENSE("GPL v2");
300 MODULE_ALIAS("platform:i2c-demux-pinctrl");