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         p = devm_pinctrl_get_select(adap->dev.parent, priv->bus_name);
  73         if (IS_ERR(p)) {
  74                 ret = PTR_ERR(p);
  75                 goto err_with_put;
  76         }
  77
  78         priv->chan[new_chan].parent_adap = adap;
  79         priv->cur_chan = new_chan;
  80
  81         /* Now fill out current adapter structure. cur_chan must be up to date */
  82         priv->algo.master_xfer = i2c_demux_master_xfer;
  83         priv->algo.functionality = i2c_demux_functionality;
  84
  85         snprintf(priv->cur_adap.name, sizeof(priv->cur_adap.name),
  86                  "i2c-demux (master i2c-%d)", i2c_adapter_id(adap));
  87         priv->cur_adap.owner = THIS_MODULE;
  88         priv->cur_adap.algo = &priv->algo;
  89         priv->cur_adap.algo_data = priv;
  90         priv->cur_adap.dev.parent = priv->dev;
  91         priv->cur_adap.class = adap->class;
  92         priv->cur_adap.retries = adap->retries;
  93         priv->cur_adap.timeout = adap->timeout;
  94         priv->cur_adap.quirks = adap->quirks;
  95         priv->cur_adap.dev.of_node = priv->dev->of_node;
  96         ret = i2c_add_adapter(&priv->cur_adap);
  97         if (ret < 0)
  98                 goto err_with_put;
  99
 100         return 0;
 101
 102  err_with_put:
 103         i2c_put_adapter(adap);
 104  err_with_revert:
 105         of_changeset_revert(&priv->chan[new_chan].chgset);
 106  err:
 107         dev_err(priv->dev, "failed to setup demux-adapter %d (%d)\n", new_chan, ret);
 108         priv->cur_chan = -EINVAL;
 109         return ret;
 110 }
 111
 112 static int i2c_demux_deactivate_master(struct i2c_demux_pinctrl_priv *priv)
 113 {
 114         int ret, cur = priv->cur_chan;
 115
 116         if (cur < 0)
 117                 return 0;
 118
 119         i2c_del_adapter(&priv->cur_adap);
 120         i2c_put_adapter(priv->chan[cur].parent_adap);
 121
 122         ret = of_changeset_revert(&priv->chan[cur].chgset);
 123
 124         priv->chan[cur].parent_adap = NULL;
 125         priv->cur_chan = -EINVAL;
 126
 127         return ret;
 128 }
 129
 130 static int i2c_demux_change_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan)
 131 {
 132         int ret;
 133
 134         if (new_chan == priv->cur_chan)
 135                 return 0;
 136
 137         ret = i2c_demux_deactivate_master(priv);
 138         if (ret)
 139                 return ret;
 140
 141         return i2c_demux_activate_master(priv, new_chan);
 142 }
 143
 144 static ssize_t available_masters_show(struct device *dev,
 145                                       struct device_attribute *attr,
 146                                       char *buf)
 147 {
 148         struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
 149         int count = 0, i;
 150
 151         for (i = 0; i < priv->num_chan && count < PAGE_SIZE; i++)
 152                 count += scnprintf(buf + count, PAGE_SIZE - count, "%d:%s%c",
 153                                    i, priv->chan[i].parent_np->full_name,
 154                                    i == priv->num_chan - 1 ? '\n' : ' ');
 155
 156         return count;
 157 }
 158 static DEVICE_ATTR_RO(available_masters);
 159
 160 static ssize_t current_master_show(struct device *dev,
 161                                    struct device_attribute *attr,
 162                                    char *buf)
 163 {
 164         struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
 165
 166         return sprintf(buf, "%d\n", priv->cur_chan);
 167 }
 168
 169 static ssize_t current_master_store(struct device *dev,
 170                                     struct device_attribute *attr,
 171                                     const char *buf, size_t count)
 172 {
 173         struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
 174         unsigned int val;
 175         int ret;
 176
 177         ret = kstrtouint(buf, 0, &val);
 178         if (ret < 0)
 179                 return ret;
 180
 181         if (val >= priv->num_chan)
 182                 return -EINVAL;
 183
 184         ret = i2c_demux_change_master(priv, val);
 185
 186         return ret < 0 ? ret : count;
 187 }
 188 static DEVICE_ATTR_RW(current_master);
 189
 190 static int i2c_demux_pinctrl_probe(struct platform_device *pdev)
 191 {
 192         struct device_node *np = pdev->dev.of_node;
 193         struct i2c_demux_pinctrl_priv *priv;
 194         struct property *props;
 195         int num_chan, i, j, err;
 196
 197         num_chan = of_count_phandle_with_args(np, "i2c-parent", NULL);
 198         if (num_chan < 2) {
 199                 dev_err(&pdev->dev, "Need at least two I2C masters to switch\n");
 200                 return -EINVAL;
 201         }
 202
 203         priv = devm_kzalloc(&pdev->dev, sizeof(*priv)
 204                            + num_chan * sizeof(struct i2c_demux_pinctrl_chan), GFP_KERNEL);
 205
 206         props = devm_kcalloc(&pdev->dev, num_chan, sizeof(*props), GFP_KERNEL);
 207
 208         if (!priv || !props)
 209                 return -ENOMEM;
 210
 211         err = of_property_read_string(np, "i2c-bus-name", &priv->bus_name);
 212         if (err)
 213                 return err;
 214
 215         for (i = 0; i < num_chan; i++) {
 216                 struct device_node *adap_np;
 217
 218                 adap_np = of_parse_phandle(np, "i2c-parent", i);
 219                 if (!adap_np) {
 220                         dev_err(&pdev->dev, "can't get phandle for parent %d\n", i);
 221                         err = -ENOENT;
 222                         goto err_rollback;
 223                 }
 224                 priv->chan[i].parent_np = adap_np;
 225
 226                 props[i].name = devm_kstrdup(&pdev->dev, "status", GFP_KERNEL);
 227                 props[i].value = devm_kstrdup(&pdev->dev, "ok", GFP_KERNEL);
 228                 props[i].length = 3;
 229
 230                 of_changeset_init(&priv->chan[i].chgset);
 231                 of_changeset_update_property(&priv->chan[i].chgset, adap_np, &props[i]);
 232         }
 233
 234         priv->num_chan = num_chan;
 235         priv->dev = &pdev->dev;
 236
 237         platform_set_drvdata(pdev, priv);
 238
 239         /* switch to first parent as active master */
 240         i2c_demux_activate_master(priv, 0);
 241
 242         err = device_create_file(&pdev->dev, &dev_attr_available_masters);
 243         if (err)
 244                 goto err_rollback;
 245
 246         err = device_create_file(&pdev->dev, &dev_attr_current_master);
 247         if (err)
 248                 goto err_rollback_available;
 249
 250         return 0;
 251
 252 err_rollback_available:
 253         device_remove_file(&pdev->dev, &dev_attr_available_masters);
 254 err_rollback:
 255         for (j = 0; j < i; j++) {
 256                 of_node_put(priv->chan[j].parent_np);
 257                 of_changeset_destroy(&priv->chan[j].chgset);
 258         }
 259
 260         return err;
 261 }
 262
 263 static int i2c_demux_pinctrl_remove(struct platform_device *pdev)
 264 {
 265         struct i2c_demux_pinctrl_priv *priv = platform_get_drvdata(pdev);
 266         int i;
 267
 268         device_remove_file(&pdev->dev, &dev_attr_current_master);
 269         device_remove_file(&pdev->dev, &dev_attr_available_masters);
 270
 271         i2c_demux_deactivate_master(priv);
 272
 273         for (i = 0; i < priv->num_chan; i++) {
 274                 of_node_put(priv->chan[i].parent_np);
 275                 of_changeset_destroy(&priv->chan[i].chgset);
 276         }
 277
 278         return 0;
 279 }
 280
 281 static const struct of_device_id i2c_demux_pinctrl_of_match[] = {
 282         { .compatible = "i2c-demux-pinctrl", },
 283         {},
 284 };
 285 MODULE_DEVICE_TABLE(of, i2c_demux_pinctrl_of_match);
 286
 287 static struct platform_driver i2c_demux_pinctrl_driver = {
 288         .driver = {
 289                 .name = "i2c-demux-pinctrl",
 290                 .of_match_table = i2c_demux_pinctrl_of_match,
 291         },
 292         .probe  = i2c_demux_pinctrl_probe,
 293         .remove = i2c_demux_pinctrl_remove,
 294 };
 295 module_platform_driver(i2c_demux_pinctrl_driver);
 296
 297 MODULE_DESCRIPTION("pinctrl-based I2C demux driver");
 298 MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
 299 MODULE_LICENSE("GPL v2");
 300 MODULE_ALIAS("platform:i2c-demux-pinctrl");