drivers/i2c/muxes/i2c-demux-pinctrl.c

   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/pm_runtime.h>
  22 #include <linux/slab.h>
  23 #include <linux/sysfs.h>
  24
  25 struct i2c_demux_pinctrl_chan {
  26         struct device_node *parent_np;
  27         struct i2c_adapter *parent_adap;
  28         struct of_changeset chgset;
  29 };
  30
  31 struct i2c_demux_pinctrl_priv {
  32         int cur_chan;
  33         int num_chan;
  34         struct device *dev;
  35         const char *bus_name;
  36         struct i2c_adapter cur_adap;
  37         struct i2c_algorithm algo;
  38         struct i2c_demux_pinctrl_chan chan[];
  39 };
  40
  41 static int i2c_demux_master_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
  42 {
  43         struct i2c_demux_pinctrl_priv *priv = adap->algo_data;
  44         struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap;
  45
  46         return __i2c_transfer(parent, msgs, num);
  47 }
  48
  49 static u32 i2c_demux_functionality(struct i2c_adapter *adap)
  50 {
  51         struct i2c_demux_pinctrl_priv *priv = adap->algo_data;
  52         struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap;
  53
  54         return parent->algo->functionality(parent);
  55 }
  56
  57 static int i2c_demux_activate_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan)
  58 {
  59         struct i2c_adapter *adap;
  60         struct pinctrl *p;
  61         int ret;
  62
  63         ret = of_changeset_apply(&priv->chan[new_chan].chgset);
  64         if (ret)
  65                 goto err;
  66
  67         adap = of_find_i2c_adapter_by_node(priv->chan[new_chan].parent_np);
  68         if (!adap) {
  69                 ret = -ENODEV;
  70                 goto err_with_revert;
  71         }
  72
  73         /*
  74          * Check if there are pinctrl states at all. Note: we cant' use
  75          * devm_pinctrl_get_select() because we need to distinguish between
  76          * the -ENODEV from devm_pinctrl_get() and pinctrl_lookup_state().
  77          */
  78         p = devm_pinctrl_get(adap->dev.parent);
  79         if (IS_ERR(p)) {
  80                 ret = PTR_ERR(p);
  81                 /* continue if just no pinctrl states (e.g. i2c-gpio), otherwise exit */
  82                 if (ret != -ENODEV)
  83                         goto err_with_put;
  84         } else {
  85                 /* there are states. check and use them */
  86                 struct pinctrl_state *s = pinctrl_lookup_state(p, priv->bus_name);
  87
  88                 if (IS_ERR(s)) {
  89                         ret = PTR_ERR(s);
  90                         goto err_with_put;
  91                 }
  92                 ret = pinctrl_select_state(p, s);
  93                 if (ret < 0)
  94                         goto err_with_put;
  95         }
  96
  97         priv->chan[new_chan].parent_adap = adap;
  98         priv->cur_chan = new_chan;
  99
 100         /* Now fill out current adapter structure. cur_chan must be up to date */
 101         priv->algo.master_xfer = i2c_demux_master_xfer;
 102         priv->algo.functionality = i2c_demux_functionality;
 103
 104         snprintf(priv->cur_adap.name, sizeof(priv->cur_adap.name),
 105                  "i2c-demux (master i2c-%d)", i2c_adapter_id(adap));
 106         priv->cur_adap.owner = THIS_MODULE;
 107         priv->cur_adap.algo = &priv->algo;
 108         priv->cur_adap.algo_data = priv;
 109         priv->cur_adap.dev.parent = &adap->dev;
 110         priv->cur_adap.class = adap->class;
 111         priv->cur_adap.retries = adap->retries;
 112         priv->cur_adap.timeout = adap->timeout;
 113         priv->cur_adap.quirks = adap->quirks;
 114         priv->cur_adap.dev.of_node = priv->dev->of_node;
 115         ret = i2c_add_adapter(&priv->cur_adap);
 116         if (ret < 0)
 117                 goto err_with_put;
 118
 119         return 0;
 120
 121  err_with_put:
 122         i2c_put_adapter(adap);
 123  err_with_revert:
 124         of_changeset_revert(&priv->chan[new_chan].chgset);
 125  err:
 126         dev_err(priv->dev, "failed to setup demux-adapter %d (%d)\n", new_chan, ret);
 127         priv->cur_chan = -EINVAL;
 128         return ret;
 129 }
 130
 131 static int i2c_demux_deactivate_master(struct i2c_demux_pinctrl_priv *priv)
 132 {
 133         int ret, cur = priv->cur_chan;
 134
 135         if (cur < 0)
 136                 return 0;
 137
 138         i2c_del_adapter(&priv->cur_adap);
 139         i2c_put_adapter(priv->chan[cur].parent_adap);
 140
 141         ret = of_changeset_revert(&priv->chan[cur].chgset);
 142
 143         priv->chan[cur].parent_adap = NULL;
 144         priv->cur_chan = -EINVAL;
 145
 146         return ret;
 147 }
 148
 149 static int i2c_demux_change_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan)
 150 {
 151         int ret;
 152
 153         if (new_chan == priv->cur_chan)
 154                 return 0;
 155
 156         ret = i2c_demux_deactivate_master(priv);
 157         if (ret)
 158                 return ret;
 159
 160         return i2c_demux_activate_master(priv, new_chan);
 161 }
 162
 163 static ssize_t available_masters_show(struct device *dev,
 164                                       struct device_attribute *attr,
 165                                       char *buf)
 166 {
 167         struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
 168         int count = 0, i;
 169
 170         for (i = 0; i < priv->num_chan && count < PAGE_SIZE; i++)
 171                 count += scnprintf(buf + count, PAGE_SIZE - count, "%d:%pOF%c",
 172                                    i, priv->chan[i].parent_np,
 173                                    i == priv->num_chan - 1 ? '\n' : ' ');
 174
 175         return count;
 176 }
 177 static DEVICE_ATTR_RO(available_masters);
 178
 179 static ssize_t current_master_show(struct device *dev,
 180                                    struct device_attribute *attr,
 181                                    char *buf)
 182 {
 183         struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
 184
 185         return sprintf(buf, "%d\n", priv->cur_chan);
 186 }
 187
 188 static ssize_t current_master_store(struct device *dev,
 189                                     struct device_attribute *attr,
 190                                     const char *buf, size_t count)
 191 {
 192         struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
 193         unsigned int val;
 194         int ret;
 195
 196         ret = kstrtouint(buf, 0, &val);
 197         if (ret < 0)
 198                 return ret;
 199
 200         if (val >= priv->num_chan)
 201                 return -EINVAL;
 202
 203         ret = i2c_demux_change_master(priv, val);
 204
 205         return ret < 0 ? ret : count;
 206 }
 207 static DEVICE_ATTR_RW(current_master);
 208
 209 static int i2c_demux_pinctrl_probe(struct platform_device *pdev)
 210 {
 211         struct device_node *np = pdev->dev.of_node;
 212         struct i2c_demux_pinctrl_priv *priv;
 213         struct property *props;
 214         int num_chan, i, j, err;
 215
 216         num_chan = of_count_phandle_with_args(np, "i2c-parent", NULL);
 217         if (num_chan < 2) {
 218                 dev_err(&pdev->dev, "Need at least two I2C masters to switch\n");
 219                 return -EINVAL;
 220         }
 221
 222         priv = devm_kzalloc(&pdev->dev, sizeof(*priv)
 223                            + num_chan * sizeof(struct i2c_demux_pinctrl_chan), GFP_KERNEL);
 224
 225         props = devm_kcalloc(&pdev->dev, num_chan, sizeof(*props), GFP_KERNEL);
 226
 227         if (!priv || !props)
 228                 return -ENOMEM;
 229
 230         err = of_property_read_string(np, "i2c-bus-name", &priv->bus_name);
 231         if (err)
 232                 return err;
 233
 234         for (i = 0; i < num_chan; i++) {
 235                 struct device_node *adap_np;
 236
 237                 adap_np = of_parse_phandle(np, "i2c-parent", i);
 238                 if (!adap_np) {
 239                         dev_err(&pdev->dev, "can't get phandle for parent %d\n", i);
 240                         err = -ENOENT;
 241                         goto err_rollback;
 242                 }
 243                 priv->chan[i].parent_np = adap_np;
 244
 245                 props[i].name = devm_kstrdup(&pdev->dev, "status", GFP_KERNEL);
 246                 props[i].value = devm_kstrdup(&pdev->dev, "ok", GFP_KERNEL);
 247                 props[i].length = 3;
 248
 249                 of_changeset_init(&priv->chan[i].chgset);
 250                 of_changeset_update_property(&priv->chan[i].chgset, adap_np, &props[i]);
 251         }
 252
 253         priv->num_chan = num_chan;
 254         priv->dev = &pdev->dev;
 255
 256         platform_set_drvdata(pdev, priv);
 257
 258         pm_runtime_no_callbacks(&pdev->dev);
 259
 260         /* switch to first parent as active master */
 261         i2c_demux_activate_master(priv, 0);
 262
 263         err = device_create_file(&pdev->dev, &dev_attr_available_masters);
 264         if (err)
 265                 goto err_rollback_activation;
 266
 267         err = device_create_file(&pdev->dev, &dev_attr_current_master);
 268         if (err)
 269                 goto err_rollback_available;
 270
 271         return 0;
 272
 273 err_rollback_available:
 274         device_remove_file(&pdev->dev, &dev_attr_available_masters);
 275 err_rollback_activation:
 276         i2c_demux_deactivate_master(priv);
 277 err_rollback:
 278         for (j = 0; j < i; j++) {
 279                 of_node_put(priv->chan[j].parent_np);
 280                 of_changeset_destroy(&priv->chan[j].chgset);
 281         }
 282
 283         return err;
 284 }
 285
 286 static int i2c_demux_pinctrl_remove(struct platform_device *pdev)
 287 {
 288         struct i2c_demux_pinctrl_priv *priv = platform_get_drvdata(pdev);
 289         int i;
 290
 291         device_remove_file(&pdev->dev, &dev_attr_current_master);
 292         device_remove_file(&pdev->dev, &dev_attr_available_masters);
 293
 294         i2c_demux_deactivate_master(priv);
 295
 296         for (i = 0; i < priv->num_chan; i++) {
 297                 of_node_put(priv->chan[i].parent_np);
 298                 of_changeset_destroy(&priv->chan[i].chgset);
 299         }
 300
 301         return 0;
 302 }
 303
 304 static const struct of_device_id i2c_demux_pinctrl_of_match[] = {
 305         { .compatible = "i2c-demux-pinctrl", },
 306         {},
 307 };
 308 MODULE_DEVICE_TABLE(of, i2c_demux_pinctrl_of_match);
 309
 310 static struct platform_driver i2c_demux_pinctrl_driver = {
 311         .driver = {
 312                 .name = "i2c-demux-pinctrl",
 313                 .of_match_table = i2c_demux_pinctrl_of_match,
 314         },
 315         .probe  = i2c_demux_pinctrl_probe,
 316         .remove = i2c_demux_pinctrl_remove,
 317 };
 318 module_platform_driver(i2c_demux_pinctrl_driver);
 319
 320 MODULE_DESCRIPTION("pinctrl-based I2C demux driver");
 321 MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
 322 MODULE_LICENSE("GPL v2");
 323 MODULE_ALIAS("platform:i2c-demux-pinctrl");