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

   1 /*
   2  * I2C multiplexer using pinctrl API
   3  *
   4  * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms and conditions of the GNU General Public License,
   8  * version 2, as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include <linux/i2c.h>
  20 #include <linux/i2c-mux.h>
  21 #include <linux/module.h>
  22 #include <linux/pinctrl/consumer.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/slab.h>
  25 #include <linux/of.h>
  26 #include "../../pinctrl/core.h"
  27
  28 struct i2c_mux_pinctrl {
  29         struct pinctrl *pinctrl;
  30         struct pinctrl_state **states;
  31 };
  32
  33 static int i2c_mux_pinctrl_select(struct i2c_mux_core *muxc, u32 chan)
  34 {
  35         struct i2c_mux_pinctrl *mux = i2c_mux_priv(muxc);
  36
  37         return pinctrl_select_state(mux->pinctrl, mux->states[chan]);
  38 }
  39
  40 static int i2c_mux_pinctrl_deselect(struct i2c_mux_core *muxc, u32 chan)
  41 {
  42         return i2c_mux_pinctrl_select(muxc, muxc->num_adapters);
  43 }
  44
  45 static struct i2c_adapter *i2c_mux_pinctrl_root_adapter(
  46         struct pinctrl_state *state)
  47 {
  48         struct i2c_adapter *root = NULL;
  49         struct pinctrl_setting *setting;
  50         struct i2c_adapter *pin_root;
  51
  52         list_for_each_entry(setting, &state->settings, node) {
  53                 pin_root = i2c_root_adapter(setting->pctldev->dev);
  54                 if (!pin_root)
  55                         return NULL;
  56                 if (!root)
  57                         root = pin_root;
  58                 else if (root != pin_root)
  59                         return NULL;
  60         }
  61
  62         return root;
  63 }
  64
  65 static struct i2c_adapter *i2c_mux_pinctrl_parent_adapter(struct device *dev)
  66 {
  67         struct device_node *np = dev->of_node;
  68         struct device_node *parent_np;
  69         struct i2c_adapter *parent;
  70
  71         parent_np = of_parse_phandle(np, "i2c-parent", 0);
  72         if (!parent_np) {
  73                 dev_err(dev, "Cannot parse i2c-parent\n");
  74                 return ERR_PTR(-ENODEV);
  75         }
  76         parent = of_find_i2c_adapter_by_node(parent_np);
  77         of_node_put(parent_np);
  78         if (!parent)
  79                 return ERR_PTR(-EPROBE_DEFER);
  80
  81         return parent;
  82 }
  83
  84 static int i2c_mux_pinctrl_probe(struct platform_device *pdev)
  85 {
  86         struct device *dev = &pdev->dev;
  87         struct device_node *np = dev->of_node;
  88         struct i2c_mux_core *muxc;
  89         struct i2c_mux_pinctrl *mux;
  90         struct i2c_adapter *parent;
  91         struct i2c_adapter *root;
  92         int num_names, i, ret;
  93         const char *name;
  94
  95         num_names = of_property_count_strings(np, "pinctrl-names");
  96         if (num_names < 0) {
  97                 dev_err(dev, "Cannot parse pinctrl-names: %d\n",
  98                         num_names);
  99                 return num_names;
 100         }
 101
 102         parent = i2c_mux_pinctrl_parent_adapter(dev);
 103         if (IS_ERR(parent))
 104                 return PTR_ERR(parent);
 105
 106         muxc = i2c_mux_alloc(parent, dev, num_names,
 107                              sizeof(*mux) + num_names * sizeof(*mux->states),
 108                              0, i2c_mux_pinctrl_select, NULL);
 109         if (!muxc) {
 110                 ret = -ENOMEM;
 111                 goto err_put_parent;
 112         }
 113         mux = i2c_mux_priv(muxc);
 114         mux->states = (struct pinctrl_state **)(mux + 1);
 115
 116         platform_set_drvdata(pdev, muxc);
 117
 118         mux->pinctrl = devm_pinctrl_get(dev);
 119         if (IS_ERR(mux->pinctrl)) {
 120                 ret = PTR_ERR(mux->pinctrl);
 121                 dev_err(dev, "Cannot get pinctrl: %d\n", ret);
 122                 goto err_put_parent;
 123         }
 124
 125         for (i = 0; i < num_names; i++) {
 126                 ret = of_property_read_string_index(np, "pinctrl-names", i,
 127                                                     &name);
 128                 if (ret < 0) {
 129                         dev_err(dev, "Cannot parse pinctrl-names: %d\n", ret);
 130                         goto err_put_parent;
 131                 }
 132
 133                 mux->states[i] = pinctrl_lookup_state(mux->pinctrl, name);
 134                 if (IS_ERR(mux->states[i])) {
 135                         ret = PTR_ERR(mux->states[i]);
 136                         dev_err(dev, "Cannot look up pinctrl state %s: %d\n",
 137                                 name, ret);
 138                         goto err_put_parent;
 139                 }
 140
 141                 if (strcmp(name, "idle"))
 142                         continue;
 143
 144                 if (i != num_names - 1) {
 145                         dev_err(dev, "idle state must be last\n");
 146                         ret = -EINVAL;
 147                         goto err_put_parent;
 148                 }
 149                 muxc->deselect = i2c_mux_pinctrl_deselect;
 150         }
 151
 152         root = i2c_root_adapter(&muxc->parent->dev);
 153
 154         muxc->mux_locked = true;
 155         for (i = 0; i < num_names; i++) {
 156                 if (root != i2c_mux_pinctrl_root_adapter(mux->states[i])) {
 157                         muxc->mux_locked = false;
 158                         break;
 159                 }
 160         }
 161         if (muxc->mux_locked)
 162                 dev_info(dev, "mux-locked i2c mux\n");
 163
 164         /* Do not add any adapter for the idle state (if it's there at all). */
 165         for (i = 0; i < num_names - !!muxc->deselect; i++) {
 166                 ret = i2c_mux_add_adapter(muxc, 0, i, 0);
 167                 if (ret)
 168                         goto err_del_adapter;
 169         }
 170
 171         return 0;
 172
 173 err_del_adapter:
 174         i2c_mux_del_adapters(muxc);
 175 err_put_parent:
 176         i2c_put_adapter(parent);
 177
 178         return ret;
 179 }
 180
 181 static int i2c_mux_pinctrl_remove(struct platform_device *pdev)
 182 {
 183         struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
 184
 185         i2c_mux_del_adapters(muxc);
 186         i2c_put_adapter(muxc->parent);
 187
 188         return 0;
 189 }
 190
 191 static const struct of_device_id i2c_mux_pinctrl_of_match[] = {
 192         { .compatible = "i2c-mux-pinctrl", },
 193         {},
 194 };
 195 MODULE_DEVICE_TABLE(of, i2c_mux_pinctrl_of_match);
 196
 197 static struct platform_driver i2c_mux_pinctrl_driver = {
 198         .driver = {
 199                 .name   = "i2c-mux-pinctrl",
 200                 .of_match_table = of_match_ptr(i2c_mux_pinctrl_of_match),
 201         },
 202         .probe  = i2c_mux_pinctrl_probe,
 203         .remove = i2c_mux_pinctrl_remove,
 204 };
 205 module_platform_driver(i2c_mux_pinctrl_driver);
 206
 207 MODULE_DESCRIPTION("pinctrl-based I2C multiplexer driver");
 208 MODULE_AUTHOR("Stephen Warren <swarren@nvidia.com>");
 209 MODULE_LICENSE("GPL v2");
 210 MODULE_ALIAS("platform:i2c-mux-pinctrl");