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 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_with_revert;
  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_with_revert:
 107         of_changeset_revert(&priv->chan[new_chan].chgset);
 108  err:
 109         dev_err(priv->dev, "failed to setup demux-adapter %d (%d)\n", new_chan, ret);
 110         priv->cur_chan = -EINVAL;
 111         return ret;
 112 }
 113
 114 static int i2c_demux_deactivate_master(struct i2c_demux_pinctrl_priv *priv)
 115 {
 116         int ret, cur = priv->cur_chan;
 117
 118         if (cur < 0)
 119                 return 0;
 120
 121         i2c_del_adapter(&priv->cur_adap);
 122         i2c_put_adapter(priv->chan[cur].parent_adap);
 123
 124         ret = of_changeset_revert(&priv->chan[cur].chgset);
 125
 126         priv->chan[cur].parent_adap = NULL;
 127         priv->cur_chan = -EINVAL;
 128
 129         return ret;
 130 }
 131
 132 static int i2c_demux_change_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan)
 133 {
 134         int ret;
 135
 136         if (new_chan == priv->cur_chan)
 137                 return 0;
 138
 139         ret = i2c_demux_deactivate_master(priv);
 140         if (ret)
 141                 return ret;
 142
 143         return i2c_demux_activate_master(priv, new_chan);
 144 }
 145
 146 static ssize_t available_masters_show(struct device *dev,
 147                                       struct device_attribute *attr,
 148                                       char *buf)
 149 {
 150         struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
 151         int count = 0, i;
 152
 153         for (i = 0; i < priv->num_chan && count < PAGE_SIZE; i++)
 154                 count += scnprintf(buf + count, PAGE_SIZE - count, "%d:%s%c",
 155                                    i, priv->chan[i].parent_np->full_name,
 156                                    i == priv->num_chan - 1 ? '\n' : ' ');
 157
 158         return count;
 159 }
 160 static DEVICE_ATTR_RO(available_masters);
 161
 162 static ssize_t current_master_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
 168         return sprintf(buf, "%d\n", priv->cur_chan);
 169 }
 170
 171 static ssize_t current_master_store(struct device *dev,
 172                                     struct device_attribute *attr,
 173                                     const char *buf, size_t count)
 174 {
 175         struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
 176         unsigned int val;
 177         int ret;
 178
 179         ret = kstrtouint(buf, 0, &val);
 180         if (ret < 0)
 181                 return ret;
 182
 183         if (val >= priv->num_chan)
 184                 return -EINVAL;
 185
 186         ret = i2c_demux_change_master(priv, val);
 187
 188         return ret < 0 ? ret : count;
 189 }
 190 static DEVICE_ATTR_RW(current_master);
 191
 192 static int i2c_demux_pinctrl_probe(struct platform_device *pdev)
 193 {
 194         struct device_node *np = pdev->dev.of_node;
 195         struct i2c_demux_pinctrl_priv *priv;
 196         int num_chan, i, j, err;
 197
 198         num_chan = of_count_phandle_with_args(np, "i2c-parent", NULL);
 199         if (num_chan < 2) {
 200                 dev_err(&pdev->dev, "Need at least two I2C masters to switch\n");
 201                 return -EINVAL;
 202         }
 203
 204         priv = devm_kzalloc(&pdev->dev, sizeof(*priv)
 205                            + num_chan * sizeof(struct i2c_demux_pinctrl_chan), GFP_KERNEL);
 206         if (!priv)
 207                 return -ENOMEM;
 208
 209         err = of_property_read_string(np, "i2c-bus-name", &priv->bus_name);
 210         if (err)
 211                 return err;
 212
 213         for (i = 0; i < num_chan; i++) {
 214                 struct device_node *adap_np;
 215
 216                 adap_np = of_parse_phandle(np, "i2c-parent", i);
 217                 if (!adap_np) {
 218                         dev_err(&pdev->dev, "can't get phandle for parent %d\n", i);
 219                         err = -ENOENT;
 220                         goto err_rollback;
 221                 }
 222                 priv->chan[i].parent_np = adap_np;
 223
 224                 of_changeset_init(&priv->chan[i].chgset);
 225                 of_changeset_update_property(&priv->chan[i].chgset, adap_np, &status_okay);
 226         }
 227
 228         priv->num_chan = num_chan;
 229         priv->dev = &pdev->dev;
 230
 231         platform_set_drvdata(pdev, priv);
 232
 233         /* switch to first parent as active master */
 234         i2c_demux_activate_master(priv, 0);
 235
 236         err = device_create_file(&pdev->dev, &dev_attr_available_masters);
 237         if (err)
 238                 goto err_rollback;
 239
 240         err = device_create_file(&pdev->dev, &dev_attr_current_master);
 241         if (err)
 242                 goto err_rollback_available;
 243
 244         return 0;
 245
 246 err_rollback_available:
 247         device_remove_file(&pdev->dev, &dev_attr_available_masters);
 248 err_rollback:
 249         for (j = 0; j < i; j++) {
 250                 of_node_put(priv->chan[j].parent_np);
 251                 of_changeset_destroy(&priv->chan[j].chgset);
 252         }
 253
 254         return err;
 255 }
 256
 257 static int i2c_demux_pinctrl_remove(struct platform_device *pdev)
 258 {
 259         struct i2c_demux_pinctrl_priv *priv = platform_get_drvdata(pdev);
 260         int i;
 261
 262         device_remove_file(&pdev->dev, &dev_attr_current_master);
 263         device_remove_file(&pdev->dev, &dev_attr_available_masters);
 264
 265         i2c_demux_deactivate_master(priv);
 266
 267         for (i = 0; i < priv->num_chan; i++) {
 268                 of_node_put(priv->chan[i].parent_np);
 269                 of_changeset_destroy(&priv->chan[i].chgset);
 270         }
 271
 272         return 0;
 273 }
 274
 275 static const struct of_device_id i2c_demux_pinctrl_of_match[] = {
 276         { .compatible = "i2c-demux-pinctrl", },
 277         {},
 278 };
 279 MODULE_DEVICE_TABLE(of, i2c_demux_pinctrl_of_match);
 280
 281 static struct platform_driver i2c_demux_pinctrl_driver = {
 282         .driver = {
 283                 .name = "i2c-demux-pinctrl",
 284                 .of_match_table = i2c_demux_pinctrl_of_match,
 285         },
 286         .probe  = i2c_demux_pinctrl_probe,
 287         .remove = i2c_demux_pinctrl_remove,
 288 };
 289 module_platform_driver(i2c_demux_pinctrl_driver);
 290
 291 MODULE_DESCRIPTION("pinctrl-based I2C demux driver");
 292 MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
 293 MODULE_LICENSE("GPL v2");
 294 MODULE_ALIAS("platform:i2c-demux-pinctrl");