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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * I2C multiplexer using pinctrl API
   4  *
   5  * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
   6  */
   7
   8 #include <linux/i2c.h>
   9 #include <linux/i2c-mux.h>
  10 #include <linux/module.h>
  11 #include <linux/pinctrl/consumer.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/slab.h>
  14 #include <linux/of.h>
  15 #include "../../pinctrl/core.h"
  16
  17 struct i2c_mux_pinctrl {
  18         struct pinctrl *pinctrl;
  19         struct pinctrl_state *states[];
  20 };
  21
  22 static int i2c_mux_pinctrl_select(struct i2c_mux_core *muxc, u32 chan)
  23 {
  24         struct i2c_mux_pinctrl *mux = i2c_mux_priv(muxc);
  25
  26         return pinctrl_select_state(mux->pinctrl, mux->states[chan]);
  27 }
  28
  29 static int i2c_mux_pinctrl_deselect(struct i2c_mux_core *muxc, u32 chan)
  30 {
  31         return i2c_mux_pinctrl_select(muxc, muxc->num_adapters);
  32 }
  33
  34 static struct i2c_adapter *i2c_mux_pinctrl_root_adapter(
  35         struct pinctrl_state *state)
  36 {
  37         struct i2c_adapter *root = NULL;
  38         struct pinctrl_setting *setting;
  39         struct i2c_adapter *pin_root;
  40
  41         list_for_each_entry(setting, &state->settings, node) {
  42                 pin_root = i2c_root_adapter(setting->pctldev->dev);
  43                 if (!pin_root)
  44                         return NULL;
  45                 if (!root)
  46                         root = pin_root;
  47                 else if (root != pin_root)
  48                         return NULL;
  49         }
  50
  51         return root;
  52 }
  53
  54 static struct i2c_adapter *i2c_mux_pinctrl_parent_adapter(struct device *dev)
  55 {
  56         struct device_node *np = dev->of_node;
  57         struct device_node *parent_np;
  58         struct i2c_adapter *parent;
  59
  60         parent_np = of_parse_phandle(np, "i2c-parent", 0);
  61         if (!parent_np) {
  62                 dev_err(dev, "Cannot parse i2c-parent\n");
  63                 return ERR_PTR(-ENODEV);
  64         }
  65         parent = of_find_i2c_adapter_by_node(parent_np);
  66         of_node_put(parent_np);
  67         if (!parent)
  68                 return ERR_PTR(-EPROBE_DEFER);
  69
  70         return parent;
  71 }
  72
  73 static int i2c_mux_pinctrl_probe(struct platform_device *pdev)
  74 {
  75         struct device *dev = &pdev->dev;
  76         struct device_node *np = dev->of_node;
  77         struct i2c_mux_core *muxc;
  78         struct i2c_mux_pinctrl *mux;
  79         struct i2c_adapter *parent;
  80         struct i2c_adapter *root;
  81         int num_names, i, ret;
  82         const char *name;
  83
  84         num_names = of_property_count_strings(np, "pinctrl-names");
  85         if (num_names < 0) {
  86                 dev_err(dev, "Cannot parse pinctrl-names: %d\n",
  87                         num_names);
  88                 return num_names;
  89         }
  90
  91         parent = i2c_mux_pinctrl_parent_adapter(dev);
  92         if (IS_ERR(parent))
  93                 return PTR_ERR(parent);
  94
  95         muxc = i2c_mux_alloc(parent, dev, num_names,
  96                              struct_size(mux, states, num_names),
  97                              0, i2c_mux_pinctrl_select, NULL);
  98         if (!muxc) {
  99                 ret = -ENOMEM;
 100                 goto err_put_parent;
 101         }
 102         mux = i2c_mux_priv(muxc);
 103
 104         platform_set_drvdata(pdev, muxc);
 105
 106         mux->pinctrl = devm_pinctrl_get(dev);
 107         if (IS_ERR(mux->pinctrl)) {
 108                 ret = PTR_ERR(mux->pinctrl);
 109                 dev_err(dev, "Cannot get pinctrl: %d\n", ret);
 110                 goto err_put_parent;
 111         }
 112
 113         for (i = 0; i < num_names; i++) {
 114                 ret = of_property_read_string_index(np, "pinctrl-names", i,
 115                                                     &name);
 116                 if (ret < 0) {
 117                         dev_err(dev, "Cannot parse pinctrl-names: %d\n", ret);
 118                         goto err_put_parent;
 119                 }
 120
 121                 mux->states[i] = pinctrl_lookup_state(mux->pinctrl, name);
 122                 if (IS_ERR(mux->states[i])) {
 123                         ret = PTR_ERR(mux->states[i]);
 124                         dev_err(dev, "Cannot look up pinctrl state %s: %d\n",
 125                                 name, ret);
 126                         goto err_put_parent;
 127                 }
 128
 129                 if (strcmp(name, "idle"))
 130                         continue;
 131
 132                 if (i != num_names - 1) {
 133                         dev_err(dev, "idle state must be last\n");
 134                         ret = -EINVAL;
 135                         goto err_put_parent;
 136                 }
 137                 muxc->deselect = i2c_mux_pinctrl_deselect;
 138         }
 139
 140         root = i2c_root_adapter(&muxc->parent->dev);
 141
 142         muxc->mux_locked = true;
 143         for (i = 0; i < num_names; i++) {
 144                 if (root != i2c_mux_pinctrl_root_adapter(mux->states[i])) {
 145                         muxc->mux_locked = false;
 146                         break;
 147                 }
 148         }
 149         if (muxc->mux_locked)
 150                 dev_info(dev, "mux-locked i2c mux\n");
 151
 152         /* Do not add any adapter for the idle state (if it's there at all). */
 153         for (i = 0; i < num_names - !!muxc->deselect; i++) {
 154                 ret = i2c_mux_add_adapter(muxc, 0, i, 0);
 155                 if (ret)
 156                         goto err_del_adapter;
 157         }
 158
 159         return 0;
 160
 161 err_del_adapter:
 162         i2c_mux_del_adapters(muxc);
 163 err_put_parent:
 164         i2c_put_adapter(parent);
 165
 166         return ret;
 167 }
 168
 169 static int i2c_mux_pinctrl_remove(struct platform_device *pdev)
 170 {
 171         struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
 172
 173         i2c_mux_del_adapters(muxc);
 174         i2c_put_adapter(muxc->parent);
 175
 176         return 0;
 177 }
 178
 179 static const struct of_device_id i2c_mux_pinctrl_of_match[] = {
 180         { .compatible = "i2c-mux-pinctrl", },
 181         {},
 182 };
 183 MODULE_DEVICE_TABLE(of, i2c_mux_pinctrl_of_match);
 184
 185 static struct platform_driver i2c_mux_pinctrl_driver = {
 186         .driver = {
 187                 .name   = "i2c-mux-pinctrl",
 188                 .of_match_table = of_match_ptr(i2c_mux_pinctrl_of_match),
 189         },
 190         .probe  = i2c_mux_pinctrl_probe,
 191         .remove = i2c_mux_pinctrl_remove,
 192 };
 193 module_platform_driver(i2c_mux_pinctrl_driver);
 194
 195 MODULE_DESCRIPTION("pinctrl-based I2C multiplexer driver");
 196 MODULE_AUTHOR("Stephen Warren <swarren@nvidia.com>");
 197 MODULE_LICENSE("GPL v2");
 198 MODULE_ALIAS("platform:i2c-mux-pinctrl");