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         return ret;
 111 }
 112
 113 static int i2c_demux_deactivate_master(struct i2c_demux_pinctrl_priv *priv)
 114 {
 115         int ret, cur = priv->cur_chan;
 116
 117         if (cur < 0)
 118                 return 0;
 119
 120         i2c_del_adapter(&priv->cur_adap);
 121         i2c_put_adapter(priv->chan[cur].parent_adap);
 122
 123         ret = of_changeset_revert(&priv->chan[cur].chgset);
 124
 125         priv->chan[cur].parent_adap = NULL;
 126         priv->cur_chan = -EINVAL;
 127
 128         return ret;
 129 }
 130
 131 static int i2c_demux_change_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan)
 132 {
 133         int ret;
 134
 135         if (new_chan == priv->cur_chan)
 136                 return 0;
 137
 138         ret = i2c_demux_deactivate_master(priv);
 139         if (ret)
 140                 return ret;
 141
 142         return i2c_demux_activate_master(priv, new_chan);
 143 }
 144
 145 static ssize_t available_masters_show(struct device *dev,
 146                                       struct device_attribute *attr,
 147                                       char *buf)
 148 {
 149         struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
 150         int count = 0, i;
 151
 152         for (i = 0; i < priv->num_chan && count < PAGE_SIZE; i++)
 153                 count += scnprintf(buf + count, PAGE_SIZE - count, "%d:%s%c",
 154                                    i, priv->chan[i].parent_np->full_name,
 155                                    i == priv->num_chan - 1 ? '\n' : ' ');
 156
 157         return count;
 158 }
 159 static DEVICE_ATTR_RO(available_masters);
 160
 161 static ssize_t current_master_show(struct device *dev,
 162                                    struct device_attribute *attr,
 163                                    char *buf)
 164 {
 165         struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
 166
 167         return sprintf(buf, "%d\n", priv->cur_chan);
 168 }
 169
 170 static ssize_t current_master_store(struct device *dev,
 171                                     struct device_attribute *attr,
 172                                     const char *buf, size_t count)
 173 {
 174         struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
 175         unsigned int val;
 176         int ret;
 177
 178         ret = kstrtouint(buf, 0, &val);
 179         if (ret < 0)
 180                 return ret;
 181
 182         if (val >= priv->num_chan)
 183                 return -EINVAL;
 184
 185         ret = i2c_demux_change_master(priv, val);
 186
 187         return ret < 0 ? ret : count;
 188 }
 189 static DEVICE_ATTR_RW(current_master);
 190
 191 static int i2c_demux_pinctrl_probe(struct platform_device *pdev)
 192 {
 193         struct device_node *np = pdev->dev.of_node;
 194         struct i2c_demux_pinctrl_priv *priv;
 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         if (!priv)
 206                 return -ENOMEM;
 207
 208         err = of_property_read_string(np, "i2c-bus-name", &priv->bus_name);
 209         if (err)
 210                 return err;
 211
 212         for (i = 0; i < num_chan; i++) {
 213                 struct device_node *adap_np;
 214
 215                 adap_np = of_parse_phandle(np, "i2c-parent", i);
 216                 if (!adap_np) {
 217                         dev_err(&pdev->dev, "can't get phandle for parent %d\n", i);
 218                         err = -ENOENT;
 219                         goto err_rollback;
 220                 }
 221                 priv->chan[i].parent_np = adap_np;
 222
 223                 of_changeset_init(&priv->chan[i].chgset);
 224                 of_changeset_update_property(&priv->chan[i].chgset, adap_np, &status_okay);
 225         }
 226
 227         priv->num_chan = num_chan;
 228         priv->dev = &pdev->dev;
 229
 230         platform_set_drvdata(pdev, priv);
 231
 232         /* switch to first parent as active master */
 233         i2c_demux_activate_master(priv, 0);
 234
 235         err = device_create_file(&pdev->dev, &dev_attr_available_masters);
 236         if (err)
 237                 goto err_rollback;
 238
 239         err = device_create_file(&pdev->dev, &dev_attr_current_master);
 240         if (err)
 241                 goto err_rollback_available;
 242
 243         return 0;
 244
 245 err_rollback_available:
 246         device_remove_file(&pdev->dev, &dev_attr_available_masters);
 247 err_rollback:
 248         for (j = 0; j < i; j++) {
 249                 of_node_put(priv->chan[j].parent_np);
 250                 of_changeset_destroy(&priv->chan[j].chgset);
 251         }
 252
 253         return err;
 254 }
 255
 256 static int i2c_demux_pinctrl_remove(struct platform_device *pdev)
 257 {
 258         struct i2c_demux_pinctrl_priv *priv = platform_get_drvdata(pdev);
 259         int i;
 260
 261         device_remove_file(&pdev->dev, &dev_attr_current_master);
 262         device_remove_file(&pdev->dev, &dev_attr_available_masters);
 263
 264         i2c_demux_deactivate_master(priv);
 265
 266         for (i = 0; i < priv->num_chan; i++) {
 267                 of_node_put(priv->chan[i].parent_np);
 268                 of_changeset_destroy(&priv->chan[i].chgset);
 269         }
 270
 271         return 0;
 272 }
 273
 274 static const struct of_device_id i2c_demux_pinctrl_of_match[] = {
 275         { .compatible = "i2c-demux-pinctrl", },
 276         {},
 277 };
 278 MODULE_DEVICE_TABLE(of, i2c_demux_pinctrl_of_match);
 279
 280 static struct platform_driver i2c_demux_pinctrl_driver = {
 281         .driver = {
 282                 .name = "i2c-demux-pinctrl",
 283                 .of_match_table = i2c_demux_pinctrl_of_match,
 284         },
 285         .probe  = i2c_demux_pinctrl_probe,
 286         .remove = i2c_demux_pinctrl_remove,
 287 };
 288 module_platform_driver(i2c_demux_pinctrl_driver);
 289
 290 MODULE_DESCRIPTION("pinctrl-based I2C demux driver");
 291 MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
 292 MODULE_LICENSE("GPL v2");
 293 MODULE_ALIAS("platform:i2c-demux-pinctrl");