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