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50a5ba87 WS |
1 | /* |
2 | * Pinctrl based I2C DeMultiplexer | |
3 | * | |
4 | * Copyright (C) 2015-16 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com> | |
5 | * Copyright (C) 2015-16 by Renesas Electronics Corporation | |
6 | * | |
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. | |
10 | * | |
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/) | |
13 | */ | |
14 | ||
15 | #include <linux/i2c.h> | |
16 | #include <linux/init.h> | |
17 | #include <linux/module.h> | |
18 | #include <linux/of.h> | |
19 | #include <linux/pinctrl/consumer.h> | |
20 | #include <linux/platform_device.h> | |
21 | #include <linux/slab.h> | |
22 | #include <linux/sysfs.h> | |
23 | ||
24 | struct i2c_demux_pinctrl_chan { | |
25 | struct device_node *parent_np; | |
26 | struct i2c_adapter *parent_adap; | |
27 | struct of_changeset chgset; | |
28 | }; | |
29 | ||
30 | struct i2c_demux_pinctrl_priv { | |
31 | int cur_chan; | |
32 | int num_chan; | |
33 | struct device *dev; | |
34 | const char *bus_name; | |
35 | struct i2c_adapter cur_adap; | |
36 | struct i2c_algorithm algo; | |
37 | struct i2c_demux_pinctrl_chan chan[]; | |
38 | }; | |
39 | ||
40 | static struct property status_okay = { .name = "status", .length = 3, .value = "ok" }; | |
41 | ||
42 | static int i2c_demux_master_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) | |
43 | { | |
44 | struct i2c_demux_pinctrl_priv *priv = adap->algo_data; | |
45 | struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap; | |
46 | ||
47 | return __i2c_transfer(parent, msgs, num); | |
48 | } | |
49 | ||
50 | static u32 i2c_demux_functionality(struct i2c_adapter *adap) | |
51 | { | |
52 | struct i2c_demux_pinctrl_priv *priv = adap->algo_data; | |
53 | struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap; | |
54 | ||
55 | return parent->algo->functionality(parent); | |
56 | } | |
57 | ||
58 | static int i2c_demux_activate_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan) | |
59 | { | |
60 | struct i2c_adapter *adap; | |
61 | struct pinctrl *p; | |
62 | int ret; | |
63 | ||
64 | ret = of_changeset_apply(&priv->chan[new_chan].chgset); | |
65 | if (ret) | |
66 | goto err; | |
67 | ||
68 | adap = of_find_i2c_adapter_by_node(priv->chan[new_chan].parent_np); | |
69 | if (!adap) { | |
70 | ret = -ENODEV; | |
71 | goto err; | |
72 | } | |
73 | ||
74 | p = devm_pinctrl_get_select(adap->dev.parent, priv->bus_name); | |
75 | if (IS_ERR(p)) { | |
76 | ret = PTR_ERR(p); | |
77 | goto err_with_put; | |
78 | } | |
79 | ||
80 | priv->chan[new_chan].parent_adap = adap; | |
81 | priv->cur_chan = new_chan; | |
82 | ||
83 | /* Now fill out current adapter structure. cur_chan must be up to date */ | |
84 | priv->algo.master_xfer = i2c_demux_master_xfer; | |
85 | priv->algo.functionality = i2c_demux_functionality; | |
86 | ||
87 | snprintf(priv->cur_adap.name, sizeof(priv->cur_adap.name), | |
88 | "i2c-demux (master i2c-%d)", i2c_adapter_id(adap)); | |
89 | priv->cur_adap.owner = THIS_MODULE; | |
90 | priv->cur_adap.algo = &priv->algo; | |
91 | priv->cur_adap.algo_data = priv; | |
92 | priv->cur_adap.dev.parent = priv->dev; | |
93 | priv->cur_adap.class = adap->class; | |
94 | priv->cur_adap.retries = adap->retries; | |
95 | priv->cur_adap.timeout = adap->timeout; | |
96 | priv->cur_adap.quirks = adap->quirks; | |
97 | priv->cur_adap.dev.of_node = priv->dev->of_node; | |
98 | ret = i2c_add_adapter(&priv->cur_adap); | |
99 | if (ret < 0) | |
100 | goto err_with_put; | |
101 | ||
102 | return 0; | |
103 | ||
104 | err_with_put: | |
105 | i2c_put_adapter(adap); | |
106 | err: | |
107 | dev_err(priv->dev, "failed to setup demux-adapter %d (%d)\n", new_chan, ret); | |
108 | return ret; | |
109 | } | |
110 | ||
111 | static int i2c_demux_deactivate_master(struct i2c_demux_pinctrl_priv *priv) | |
112 | { | |
113 | int ret, cur = priv->cur_chan; | |
114 | ||
115 | if (cur < 0) | |
116 | return 0; | |
117 | ||
118 | i2c_del_adapter(&priv->cur_adap); | |
119 | i2c_put_adapter(priv->chan[cur].parent_adap); | |
120 | ||
121 | ret = of_changeset_revert(&priv->chan[cur].chgset); | |
122 | ||
123 | priv->chan[cur].parent_adap = NULL; | |
124 | priv->cur_chan = -EINVAL; | |
125 | ||
126 | return ret; | |
127 | } | |
128 | ||
129 | static int i2c_demux_change_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan) | |
130 | { | |
131 | int ret; | |
132 | ||
133 | if (new_chan == priv->cur_chan) | |
134 | return 0; | |
135 | ||
136 | ret = i2c_demux_deactivate_master(priv); | |
137 | if (ret) | |
138 | return ret; | |
139 | ||
140 | return i2c_demux_activate_master(priv, new_chan); | |
141 | } | |
142 | ||
c0c508a4 BH |
143 | static ssize_t available_masters_show(struct device *dev, |
144 | struct device_attribute *attr, | |
145 | char *buf) | |
50a5ba87 WS |
146 | { |
147 | struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev); | |
148 | int count = 0, i; | |
149 | ||
150 | for (i = 0; i < priv->num_chan && count < PAGE_SIZE; i++) | |
c0c508a4 BH |
151 | count += scnprintf(buf + count, PAGE_SIZE - count, "%d:%s%c", |
152 | i, priv->chan[i].parent_np->full_name, | |
153 | i == priv->num_chan - 1 ? '\n' : ' '); | |
50a5ba87 WS |
154 | |
155 | return count; | |
156 | } | |
c0c508a4 | 157 | static DEVICE_ATTR_RO(available_masters); |
50a5ba87 | 158 | |
c0c508a4 BH |
159 | static ssize_t current_master_show(struct device *dev, |
160 | struct device_attribute *attr, | |
161 | char *buf) | |
162 | { | |
163 | struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev); | |
164 | ||
165 | return sprintf(buf, "%d\n", priv->cur_chan); | |
166 | } | |
167 | ||
168 | static ssize_t current_master_store(struct device *dev, | |
169 | struct device_attribute *attr, | |
170 | const char *buf, size_t count) | |
50a5ba87 WS |
171 | { |
172 | struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev); | |
173 | unsigned int val; | |
174 | int ret; | |
175 | ||
176 | ret = kstrtouint(buf, 0, &val); | |
177 | if (ret < 0) | |
178 | return ret; | |
179 | ||
180 | if (val >= priv->num_chan) | |
181 | return -EINVAL; | |
182 | ||
183 | ret = i2c_demux_change_master(priv, val); | |
184 | ||
185 | return ret < 0 ? ret : count; | |
186 | } | |
c0c508a4 | 187 | static DEVICE_ATTR_RW(current_master); |
50a5ba87 WS |
188 | |
189 | static int i2c_demux_pinctrl_probe(struct platform_device *pdev) | |
190 | { | |
191 | struct device_node *np = pdev->dev.of_node; | |
192 | struct i2c_demux_pinctrl_priv *priv; | |
193 | int num_chan, i, j, err; | |
194 | ||
195 | num_chan = of_count_phandle_with_args(np, "i2c-parent", NULL); | |
196 | if (num_chan < 2) { | |
197 | dev_err(&pdev->dev, "Need at least two I2C masters to switch\n"); | |
198 | return -EINVAL; | |
199 | } | |
200 | ||
201 | priv = devm_kzalloc(&pdev->dev, sizeof(*priv) | |
202 | + num_chan * sizeof(struct i2c_demux_pinctrl_chan), GFP_KERNEL); | |
203 | if (!priv) | |
204 | return -ENOMEM; | |
205 | ||
206 | err = of_property_read_string(np, "i2c-bus-name", &priv->bus_name); | |
207 | if (err) | |
208 | return err; | |
209 | ||
210 | for (i = 0; i < num_chan; i++) { | |
211 | struct device_node *adap_np; | |
212 | ||
213 | adap_np = of_parse_phandle(np, "i2c-parent", i); | |
214 | if (!adap_np) { | |
215 | dev_err(&pdev->dev, "can't get phandle for parent %d\n", i); | |
216 | err = -ENOENT; | |
217 | goto err_rollback; | |
218 | } | |
219 | priv->chan[i].parent_np = adap_np; | |
220 | ||
221 | of_changeset_init(&priv->chan[i].chgset); | |
222 | of_changeset_update_property(&priv->chan[i].chgset, adap_np, &status_okay); | |
223 | } | |
224 | ||
225 | priv->num_chan = num_chan; | |
226 | priv->dev = &pdev->dev; | |
227 | ||
228 | platform_set_drvdata(pdev, priv); | |
229 | ||
230 | /* switch to first parent as active master */ | |
231 | i2c_demux_activate_master(priv, 0); | |
232 | ||
c0c508a4 | 233 | err = device_create_file(&pdev->dev, &dev_attr_available_masters); |
50a5ba87 WS |
234 | if (err) |
235 | goto err_rollback; | |
236 | ||
c0c508a4 BH |
237 | err = device_create_file(&pdev->dev, &dev_attr_current_master); |
238 | if (err) | |
239 | goto err_rollback_available; | |
240 | ||
50a5ba87 WS |
241 | return 0; |
242 | ||
c0c508a4 BH |
243 | err_rollback_available: |
244 | device_remove_file(&pdev->dev, &dev_attr_available_masters); | |
50a5ba87 WS |
245 | err_rollback: |
246 | for (j = 0; j < i; j++) { | |
247 | of_node_put(priv->chan[j].parent_np); | |
248 | of_changeset_destroy(&priv->chan[j].chgset); | |
249 | } | |
250 | ||
251 | return err; | |
252 | } | |
253 | ||
254 | static int i2c_demux_pinctrl_remove(struct platform_device *pdev) | |
255 | { | |
256 | struct i2c_demux_pinctrl_priv *priv = platform_get_drvdata(pdev); | |
257 | int i; | |
258 | ||
c0c508a4 BH |
259 | device_remove_file(&pdev->dev, &dev_attr_current_master); |
260 | device_remove_file(&pdev->dev, &dev_attr_available_masters); | |
50a5ba87 WS |
261 | |
262 | i2c_demux_deactivate_master(priv); | |
263 | ||
264 | for (i = 0; i < priv->num_chan; i++) { | |
265 | of_node_put(priv->chan[i].parent_np); | |
266 | of_changeset_destroy(&priv->chan[i].chgset); | |
267 | } | |
268 | ||
269 | return 0; | |
270 | } | |
271 | ||
272 | static const struct of_device_id i2c_demux_pinctrl_of_match[] = { | |
273 | { .compatible = "i2c-demux-pinctrl", }, | |
274 | {}, | |
275 | }; | |
276 | MODULE_DEVICE_TABLE(of, i2c_demux_pinctrl_of_match); | |
277 | ||
278 | static struct platform_driver i2c_demux_pinctrl_driver = { | |
279 | .driver = { | |
280 | .name = "i2c-demux-pinctrl", | |
281 | .of_match_table = i2c_demux_pinctrl_of_match, | |
282 | }, | |
283 | .probe = i2c_demux_pinctrl_probe, | |
284 | .remove = i2c_demux_pinctrl_remove, | |
285 | }; | |
286 | module_platform_driver(i2c_demux_pinctrl_driver); | |
287 | ||
288 | MODULE_DESCRIPTION("pinctrl-based I2C demux driver"); | |
289 | MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>"); | |
290 | MODULE_LICENSE("GPL v2"); | |
291 | MODULE_ALIAS("platform:i2c-demux-pinctrl"); |