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Linux/drivers/i2c/muxes/i2c-mux-pinctrl.c

  1 /*
  2  * I2C multiplexer using pinctrl API
  3  *
  4  * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
  5  *
  6  * This program is free software; you can redistribute it and/or modify it
  7  * under the terms and conditions of the GNU General Public License,
  8  * version 2, as published by the Free Software Foundation.
  9  *
 10  * This program is distributed in the hope it will be useful, but WITHOUT
 11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 13  * more details.
 14  *
 15  * You should have received a copy of the GNU General Public License
 16  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 17  */
 18 
 19 #include <linux/i2c.h>
 20 #include <linux/i2c-mux.h>
 21 #include <linux/module.h>
 22 #include <linux/pinctrl/consumer.h>
 23 #include <linux/i2c-mux-pinctrl.h>
 24 #include <linux/platform_device.h>
 25 #include <linux/slab.h>
 26 #include <linux/of.h>
 27 #include "../../pinctrl/core.h"
 28 
 29 struct i2c_mux_pinctrl {
 30         struct i2c_mux_pinctrl_platform_data *pdata;
 31         struct pinctrl *pinctrl;
 32         struct pinctrl_state **states;
 33         struct pinctrl_state *state_idle;
 34 };
 35 
 36 static int i2c_mux_pinctrl_select(struct i2c_mux_core *muxc, u32 chan)
 37 {
 38         struct i2c_mux_pinctrl *mux = i2c_mux_priv(muxc);
 39 
 40         return pinctrl_select_state(mux->pinctrl, mux->states[chan]);
 41 }
 42 
 43 static int i2c_mux_pinctrl_deselect(struct i2c_mux_core *muxc, u32 chan)
 44 {
 45         struct i2c_mux_pinctrl *mux = i2c_mux_priv(muxc);
 46 
 47         return pinctrl_select_state(mux->pinctrl, mux->state_idle);
 48 }
 49 
 50 #ifdef CONFIG_OF
 51 static int i2c_mux_pinctrl_parse_dt(struct i2c_mux_pinctrl *mux,
 52                                     struct platform_device *pdev)
 53 {
 54         struct device_node *np = pdev->dev.of_node;
 55         int num_names, i, ret;
 56         struct device_node *adapter_np;
 57         struct i2c_adapter *adapter;
 58 
 59         if (!np)
 60                 return 0;
 61 
 62         mux->pdata = devm_kzalloc(&pdev->dev, sizeof(*mux->pdata), GFP_KERNEL);
 63         if (!mux->pdata)
 64                 return -ENOMEM;
 65 
 66         num_names = of_property_count_strings(np, "pinctrl-names");
 67         if (num_names < 0) {
 68                 dev_err(&pdev->dev, "Cannot parse pinctrl-names: %d\n",
 69                         num_names);
 70                 return num_names;
 71         }
 72 
 73         mux->pdata->pinctrl_states = devm_kzalloc(&pdev->dev,
 74                 sizeof(*mux->pdata->pinctrl_states) * num_names,
 75                 GFP_KERNEL);
 76         if (!mux->pdata->pinctrl_states)
 77                 return -ENOMEM;
 78 
 79         for (i = 0; i < num_names; i++) {
 80                 ret = of_property_read_string_index(np, "pinctrl-names", i,
 81                         &mux->pdata->pinctrl_states[mux->pdata->bus_count]);
 82                 if (ret < 0) {
 83                         dev_err(&pdev->dev, "Cannot parse pinctrl-names: %d\n",
 84                                 ret);
 85                         return ret;
 86                 }
 87                 if (!strcmp(mux->pdata->pinctrl_states[mux->pdata->bus_count],
 88                             "idle")) {
 89                         if (i != num_names - 1) {
 90                                 dev_err(&pdev->dev,
 91                                         "idle state must be last\n");
 92                                 return -EINVAL;
 93                         }
 94                         mux->pdata->pinctrl_state_idle = "idle";
 95                 } else {
 96                         mux->pdata->bus_count++;
 97                 }
 98         }
 99 
100         adapter_np = of_parse_phandle(np, "i2c-parent", 0);
101         if (!adapter_np) {
102                 dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
103                 return -ENODEV;
104         }
105         adapter = of_find_i2c_adapter_by_node(adapter_np);
106         of_node_put(adapter_np);
107         if (!adapter) {
108                 dev_err(&pdev->dev, "Cannot find parent bus\n");
109                 return -EPROBE_DEFER;
110         }
111         mux->pdata->parent_bus_num = i2c_adapter_id(adapter);
112         put_device(&adapter->dev);
113 
114         return 0;
115 }
116 #else
117 static inline int i2c_mux_pinctrl_parse_dt(struct i2c_mux_pinctrl *mux,
118                                            struct platform_device *pdev)
119 {
120         return 0;
121 }
122 #endif
123 
124 static struct i2c_adapter *i2c_mux_pinctrl_root_adapter(
125         struct pinctrl_state *state)
126 {
127         struct i2c_adapter *root = NULL;
128         struct pinctrl_setting *setting;
129         struct i2c_adapter *pin_root;
130 
131         list_for_each_entry(setting, &state->settings, node) {
132                 pin_root = i2c_root_adapter(setting->pctldev->dev);
133                 if (!pin_root)
134                         return NULL;
135                 if (!root)
136                         root = pin_root;
137                 else if (root != pin_root)
138                         return NULL;
139         }
140 
141         return root;
142 }
143 
144 static int i2c_mux_pinctrl_probe(struct platform_device *pdev)
145 {
146         struct i2c_mux_core *muxc;
147         struct i2c_mux_pinctrl *mux;
148         struct i2c_adapter *root;
149         int i, ret;
150 
151         mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
152         if (!mux) {
153                 ret = -ENOMEM;
154                 goto err;
155         }
156 
157         mux->pdata = dev_get_platdata(&pdev->dev);
158         if (!mux->pdata) {
159                 ret = i2c_mux_pinctrl_parse_dt(mux, pdev);
160                 if (ret < 0)
161                         goto err;
162         }
163         if (!mux->pdata) {
164                 dev_err(&pdev->dev, "Missing platform data\n");
165                 ret = -ENODEV;
166                 goto err;
167         }
168 
169         mux->states = devm_kzalloc(&pdev->dev,
170                                    sizeof(*mux->states) * mux->pdata->bus_count,
171                                    GFP_KERNEL);
172         if (!mux->states) {
173                 dev_err(&pdev->dev, "Cannot allocate states\n");
174                 ret = -ENOMEM;
175                 goto err;
176         }
177 
178         muxc = i2c_mux_alloc(NULL, &pdev->dev, mux->pdata->bus_count, 0, 0,
179                              i2c_mux_pinctrl_select, NULL);
180         if (!muxc) {
181                 ret = -ENOMEM;
182                 goto err;
183         }
184         muxc->priv = mux;
185 
186         platform_set_drvdata(pdev, muxc);
187 
188         mux->pinctrl = devm_pinctrl_get(&pdev->dev);
189         if (IS_ERR(mux->pinctrl)) {
190                 ret = PTR_ERR(mux->pinctrl);
191                 dev_err(&pdev->dev, "Cannot get pinctrl: %d\n", ret);
192                 goto err;
193         }
194         for (i = 0; i < mux->pdata->bus_count; i++) {
195                 mux->states[i] = pinctrl_lookup_state(mux->pinctrl,
196                                                 mux->pdata->pinctrl_states[i]);
197                 if (IS_ERR(mux->states[i])) {
198                         ret = PTR_ERR(mux->states[i]);
199                         dev_err(&pdev->dev,
200                                 "Cannot look up pinctrl state %s: %d\n",
201                                 mux->pdata->pinctrl_states[i], ret);
202                         goto err;
203                 }
204         }
205         if (mux->pdata->pinctrl_state_idle) {
206                 mux->state_idle = pinctrl_lookup_state(mux->pinctrl,
207                                                 mux->pdata->pinctrl_state_idle);
208                 if (IS_ERR(mux->state_idle)) {
209                         ret = PTR_ERR(mux->state_idle);
210                         dev_err(&pdev->dev,
211                                 "Cannot look up pinctrl state %s: %d\n",
212                                 mux->pdata->pinctrl_state_idle, ret);
213                         goto err;
214                 }
215 
216                 muxc->deselect = i2c_mux_pinctrl_deselect;
217         }
218 
219         muxc->parent = i2c_get_adapter(mux->pdata->parent_bus_num);
220         if (!muxc->parent) {
221                 dev_err(&pdev->dev, "Parent adapter (%d) not found\n",
222                         mux->pdata->parent_bus_num);
223                 ret = -EPROBE_DEFER;
224                 goto err;
225         }
226 
227         root = i2c_root_adapter(&muxc->parent->dev);
228 
229         muxc->mux_locked = true;
230         for (i = 0; i < mux->pdata->bus_count; i++) {
231                 if (root != i2c_mux_pinctrl_root_adapter(mux->states[i])) {
232                         muxc->mux_locked = false;
233                         break;
234                 }
235         }
236         if (muxc->mux_locked && mux->pdata->pinctrl_state_idle &&
237             root != i2c_mux_pinctrl_root_adapter(mux->state_idle))
238                 muxc->mux_locked = false;
239 
240         if (muxc->mux_locked)
241                 dev_info(&pdev->dev, "mux-locked i2c mux\n");
242 
243         for (i = 0; i < mux->pdata->bus_count; i++) {
244                 u32 bus = mux->pdata->base_bus_num ?
245                                 (mux->pdata->base_bus_num + i) : 0;
246 
247                 ret = i2c_mux_add_adapter(muxc, bus, i, 0);
248                 if (ret) {
249                         dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
250                         goto err_del_adapter;
251                 }
252         }
253 
254         return 0;
255 
256 err_del_adapter:
257         i2c_mux_del_adapters(muxc);
258         i2c_put_adapter(muxc->parent);
259 err:
260         return ret;
261 }
262 
263 static int i2c_mux_pinctrl_remove(struct platform_device *pdev)
264 {
265         struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
266 
267         i2c_mux_del_adapters(muxc);
268         i2c_put_adapter(muxc->parent);
269         return 0;
270 }
271 
272 #ifdef CONFIG_OF
273 static const struct of_device_id i2c_mux_pinctrl_of_match[] = {
274         { .compatible = "i2c-mux-pinctrl", },
275         {},
276 };
277 MODULE_DEVICE_TABLE(of, i2c_mux_pinctrl_of_match);
278 #endif
279 
280 static struct platform_driver i2c_mux_pinctrl_driver = {
281         .driver = {
282                 .name   = "i2c-mux-pinctrl",
283                 .of_match_table = of_match_ptr(i2c_mux_pinctrl_of_match),
284         },
285         .probe  = i2c_mux_pinctrl_probe,
286         .remove = i2c_mux_pinctrl_remove,
287 };
288 module_platform_driver(i2c_mux_pinctrl_driver);
289 
290 MODULE_DESCRIPTION("pinctrl-based I2C multiplexer driver");
291 MODULE_AUTHOR("Stephen Warren <swarren@nvidia.com>");
292 MODULE_LICENSE("GPL v2");
293 MODULE_ALIAS("platform:i2c-mux-pinctrl");
294 

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