drivers/i2c/muxes/i2c-demux-pinctrl.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Pinctrl based I2C DeMultiplexer
   4  *
   5  * Copyright (C) 2015-16 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
   6  * Copyright (C) 2015-16 by Renesas Electronics Corporation
   7  *
   8  * See the bindings doc for DTS setup and the sysfs doc for usage information.
   9  * (look for filenames containing 'i2c-demux-pinctrl' in Documentation/)
  10  */
  11
  12 #include <linux/i2c.h>
  13 #include <linux/init.h>
  14 #include <linux/module.h>
  15 #include <linux/of.h>
  16 #include <linux/pinctrl/consumer.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/pm_runtime.h>
  19 #include <linux/slab.h>
  20 #include <linux/sysfs.h>
  21
  22 struct i2c_demux_pinctrl_chan {
  23         struct device_node *parent_np;
  24         struct i2c_adapter *parent_adap;
  25         struct of_changeset chgset;
  26 };
  27
  28 struct i2c_demux_pinctrl_priv {
  29         int cur_chan;
  30         int num_chan;
  31         struct device *dev;
  32         const char *bus_name;
  33         struct i2c_adapter cur_adap;
  34         struct i2c_algorithm algo;
  35         struct i2c_demux_pinctrl_chan chan[];
  36 };
  37
  38 static int i2c_demux_master_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
  39 {
  40         struct i2c_demux_pinctrl_priv *priv = adap->algo_data;
  41         struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap;
  42
  43         return __i2c_transfer(parent, msgs, num);
  44 }
  45
  46 static u32 i2c_demux_functionality(struct i2c_adapter *adap)
  47 {
  48         struct i2c_demux_pinctrl_priv *priv = adap->algo_data;
  49         struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap;
  50
  51         return parent->algo->functionality(parent);
  52 }
  53
  54 static int i2c_demux_activate_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan)
  55 {
  56         struct i2c_adapter *adap;
  57         struct pinctrl *p;
  58         int ret;
  59
  60         ret = of_changeset_apply(&priv->chan[new_chan].chgset);
  61         if (ret)
  62                 goto err;
  63
  64         adap = of_find_i2c_adapter_by_node(priv->chan[new_chan].parent_np);
  65         if (!adap) {
  66                 ret = -ENODEV;
  67                 goto err_with_revert;
  68         }
  69
  70         /*
  71          * Check if there are pinctrl states at all. Note: we cant' use
  72          * devm_pinctrl_get_select() because we need to distinguish between
  73          * the -ENODEV from devm_pinctrl_get() and pinctrl_lookup_state().
  74          */
  75         p = devm_pinctrl_get(adap->dev.parent);
  76         if (IS_ERR(p)) {
  77                 ret = PTR_ERR(p);
  78                 /* continue if just no pinctrl states (e.g. i2c-gpio), otherwise exit */
  79                 if (ret != -ENODEV)
  80                         goto err_with_put;
  81         } else {
  82                 /* there are states. check and use them */
  83                 struct pinctrl_state *s = pinctrl_lookup_state(p, priv->bus_name);
  84
  85                 if (IS_ERR(s)) {
  86                         ret = PTR_ERR(s);
  87                         goto err_with_put;
  88                 }
  89                 ret = pinctrl_select_state(p, s);
  90                 if (ret < 0)
  91                         goto err_with_put;
  92         }
  93
  94         priv->chan[new_chan].parent_adap = adap;
  95         priv->cur_chan = new_chan;
  96
  97         /* Now fill out current adapter structure. cur_chan must be up to date */
  98         priv->algo.master_xfer = i2c_demux_master_xfer;
  99         if (adap->algo->master_xfer_atomic)
 100                 priv->algo.master_xfer_atomic = 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 = &adap->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:%pOF%c",
 171                                    i, priv->chan[i].parent_np,
 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, struct_size(priv, chan, num_chan),
 222                             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         pm_runtime_no_callbacks(&pdev->dev);
 258
 259         /* switch to first parent as active master */
 260         i2c_demux_activate_master(priv, 0);
 261
 262         err = device_create_file(&pdev->dev, &dev_attr_available_masters);
 263         if (err)
 264                 goto err_rollback;
 265
 266         err = device_create_file(&pdev->dev, &dev_attr_current_master);
 267         if (err)
 268                 goto err_rollback_available;
 269
 270         return 0;
 271
 272 err_rollback_available:
 273         device_remove_file(&pdev->dev, &dev_attr_available_masters);
 274 err_rollback:
 275         i2c_demux_deactivate_master(priv);
 276         for (j = 0; j < i; j++) {
 277                 of_node_put(priv->chan[j].parent_np);
 278                 of_changeset_destroy(&priv->chan[j].chgset);
 279         }
 280
 281         return err;
 282 }
 283
 284 static int i2c_demux_pinctrl_remove(struct platform_device *pdev)
 285 {
 286         struct i2c_demux_pinctrl_priv *priv = platform_get_drvdata(pdev);
 287         int i;
 288
 289         device_remove_file(&pdev->dev, &dev_attr_current_master);
 290         device_remove_file(&pdev->dev, &dev_attr_available_masters);
 291
 292         i2c_demux_deactivate_master(priv);
 293
 294         for (i = 0; i < priv->num_chan; i++) {
 295                 of_node_put(priv->chan[i].parent_np);
 296                 of_changeset_destroy(&priv->chan[i].chgset);
 297         }
 298
 299         return 0;
 300 }
 301
 302 static const struct of_device_id i2c_demux_pinctrl_of_match[] = {
 303         { .compatible = "i2c-demux-pinctrl", },
 304         {},
 305 };
 306 MODULE_DEVICE_TABLE(of, i2c_demux_pinctrl_of_match);
 307
 308 static struct platform_driver i2c_demux_pinctrl_driver = {
 309         .driver = {
 310                 .name = "i2c-demux-pinctrl",
 311                 .of_match_table = i2c_demux_pinctrl_of_match,
 312         },
 313         .probe  = i2c_demux_pinctrl_probe,
 314         .remove = i2c_demux_pinctrl_remove,
 315 };
 316 module_platform_driver(i2c_demux_pinctrl_driver);
 317
 318 MODULE_DESCRIPTION("pinctrl-based I2C demux driver");
 319 MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
 320 MODULE_LICENSE("GPL v2");
 321 MODULE_ALIAS("platform:i2c-demux-pinctrl");