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;
  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:
 107         dev_err(priv->dev, "failed to setup demux-adapter %d (%d)\n", new_chan, ret);
 108         return ret;
 109 }
 110
 111 static int i2c_demux_deactivate_master(struct i2c_demux_pinctrl_priv *priv)
 112 {
 113         int ret, cur = priv->cur_chan;
 114
 115         if (cur < 0)
 116                 return 0;
 117
 118         i2c_del_adapter(&priv->cur_adap);
 119         i2c_put_adapter(priv->chan[cur].parent_adap);
 120
 121         ret = of_changeset_revert(&priv->chan[cur].chgset);
 122
 123         priv->chan[cur].parent_adap = NULL;
 124         priv->cur_chan = -EINVAL;
 125
 126         return ret;
 127 }
 128
 129 static int i2c_demux_change_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan)
 130 {
 131         int ret;
 132
 133         if (new_chan == priv->cur_chan)
 134                 return 0;
 135
 136         ret = i2c_demux_deactivate_master(priv);
 137         if (ret)
 138                 return ret;
 139
 140         return i2c_demux_activate_master(priv, new_chan);
 141 }
 142
 143 static ssize_t cur_master_show(struct device *dev, struct device_attribute *attr,
 144                            char *buf)
 145 {
 146         struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
 147         int count = 0, i;
 148
 149         for (i = 0; i < priv->num_chan && count < PAGE_SIZE; i++)
 150                 count += scnprintf(buf + count, PAGE_SIZE - count, "%c %d - %s\n",
 151                                  i == priv->cur_chan ? '*' : ' ', i,
 152                                  priv->chan[i].parent_np->full_name);
 153
 154         return count;
 155 }
 156
 157 static ssize_t cur_master_store(struct device *dev, struct device_attribute *attr,
 158                             const char *buf, size_t count)
 159 {
 160         struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
 161         unsigned int val;
 162         int ret;
 163
 164         ret = kstrtouint(buf, 0, &val);
 165         if (ret < 0)
 166                 return ret;
 167
 168         if (val >= priv->num_chan)
 169                 return -EINVAL;
 170
 171         ret = i2c_demux_change_master(priv, val);
 172
 173         return ret < 0 ? ret : count;
 174 }
 175 static DEVICE_ATTR_RW(cur_master);
 176
 177 static int i2c_demux_pinctrl_probe(struct platform_device *pdev)
 178 {
 179         struct device_node *np = pdev->dev.of_node;
 180         struct i2c_demux_pinctrl_priv *priv;
 181         int num_chan, i, j, err;
 182
 183         num_chan = of_count_phandle_with_args(np, "i2c-parent", NULL);
 184         if (num_chan < 2) {
 185                 dev_err(&pdev->dev, "Need at least two I2C masters to switch\n");
 186                 return -EINVAL;
 187         }
 188
 189         priv = devm_kzalloc(&pdev->dev, sizeof(*priv)
 190                            + num_chan * sizeof(struct i2c_demux_pinctrl_chan), GFP_KERNEL);
 191         if (!priv)
 192                 return -ENOMEM;
 193
 194         err = of_property_read_string(np, "i2c-bus-name", &priv->bus_name);
 195         if (err)
 196                 return err;
 197
 198         for (i = 0; i < num_chan; i++) {
 199                 struct device_node *adap_np;
 200
 201                 adap_np = of_parse_phandle(np, "i2c-parent", i);
 202                 if (!adap_np) {
 203                         dev_err(&pdev->dev, "can't get phandle for parent %d\n", i);
 204                         err = -ENOENT;
 205                         goto err_rollback;
 206                 }
 207                 priv->chan[i].parent_np = adap_np;
 208
 209                 of_changeset_init(&priv->chan[i].chgset);
 210                 of_changeset_update_property(&priv->chan[i].chgset, adap_np, &status_okay);
 211         }
 212
 213         priv->num_chan = num_chan;
 214         priv->dev = &pdev->dev;
 215
 216         platform_set_drvdata(pdev, priv);
 217
 218         /* switch to first parent as active master */
 219         i2c_demux_activate_master(priv, 0);
 220
 221         err = device_create_file(&pdev->dev, &dev_attr_cur_master);
 222         if (err)
 223                 goto err_rollback;
 224
 225         return 0;
 226
 227 err_rollback:
 228         for (j = 0; j < i; j++) {
 229                 of_node_put(priv->chan[j].parent_np);
 230                 of_changeset_destroy(&priv->chan[j].chgset);
 231         }
 232
 233         return err;
 234 }
 235
 236 static int i2c_demux_pinctrl_remove(struct platform_device *pdev)
 237 {
 238         struct i2c_demux_pinctrl_priv *priv = platform_get_drvdata(pdev);
 239         int i;
 240
 241         device_remove_file(&pdev->dev, &dev_attr_cur_master);
 242
 243         i2c_demux_deactivate_master(priv);
 244
 245         for (i = 0; i < priv->num_chan; i++) {
 246                 of_node_put(priv->chan[i].parent_np);
 247                 of_changeset_destroy(&priv->chan[i].chgset);
 248         }
 249
 250         return 0;
 251 }
 252
 253 static const struct of_device_id i2c_demux_pinctrl_of_match[] = {
 254         { .compatible = "i2c-demux-pinctrl", },
 255         {},
 256 };
 257 MODULE_DEVICE_TABLE(of, i2c_demux_pinctrl_of_match);
 258
 259 static struct platform_driver i2c_demux_pinctrl_driver = {
 260         .driver = {
 261                 .name = "i2c-demux-pinctrl",
 262                 .of_match_table = i2c_demux_pinctrl_of_match,
 263         },
 264         .probe  = i2c_demux_pinctrl_probe,
 265         .remove = i2c_demux_pinctrl_remove,
 266 };
 267 module_platform_driver(i2c_demux_pinctrl_driver);
 268
 269 MODULE_DESCRIPTION("pinctrl-based I2C demux driver");
 270 MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
 271 MODULE_LICENSE("GPL v2");
 272 MODULE_ALIAS("platform:i2c-demux-pinctrl");