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

   1 /*
   2  * I2C multiplexer using a single register
   3  *
   4  * Copyright 2015 Freescale Semiconductor
   5  * York Sun  <yorksun@freescale.com>
   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; either version 2 of the License, or (at your
  10  * option) any later version.
  11  */
  12
  13 #include <linux/i2c.h>
  14 #include <linux/i2c-mux.h>
  15 #include <linux/init.h>
  16 #include <linux/io.h>
  17 #include <linux/module.h>
  18 #include <linux/of_address.h>
  19 #include <linux/platform_data/i2c-mux-reg.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/slab.h>
  22
  23 struct regmux {
  24         struct i2c_adapter *parent;
  25         struct i2c_adapter **adap; /* child busses */
  26         struct i2c_mux_reg_platform_data data;
  27 };
  28
  29 static int i2c_mux_reg_set(const struct regmux *mux, unsigned int chan_id)
  30 {
  31         if (!mux->data.reg)
  32                 return -EINVAL;
  33
  34         switch (mux->data.reg_size) {
  35         case 4:
  36                 if (mux->data.little_endian) {
  37                         iowrite32(chan_id, mux->data.reg);
  38                         if (!mux->data.write_only)
  39                                 ioread32(mux->data.reg);
  40                 } else {
  41                         iowrite32be(chan_id, mux->data.reg);
  42                         if (!mux->data.write_only)
  43                                 ioread32(mux->data.reg);
  44                 }
  45                 break;
  46         case 2:
  47                 if (mux->data.little_endian) {
  48                         iowrite16(chan_id, mux->data.reg);
  49                         if (!mux->data.write_only)
  50                                 ioread16(mux->data.reg);
  51                 } else {
  52                         iowrite16be(chan_id, mux->data.reg);
  53                         if (!mux->data.write_only)
  54                                 ioread16be(mux->data.reg);
  55                 }
  56                 break;
  57         case 1:
  58                 iowrite8(chan_id, mux->data.reg);
  59                 if (!mux->data.write_only)
  60                         ioread8(mux->data.reg);
  61                 break;
  62         default:
  63                 pr_err("Invalid register size\n");
  64                 return -EINVAL;
  65         }
  66
  67         return 0;
  68 }
  69
  70 static int i2c_mux_reg_select(struct i2c_adapter *adap, void *data,
  71                               unsigned int chan)
  72 {
  73         struct regmux *mux = data;
  74
  75         return i2c_mux_reg_set(mux, chan);
  76 }
  77
  78 static int i2c_mux_reg_deselect(struct i2c_adapter *adap, void *data,
  79                                 unsigned int chan)
  80 {
  81         struct regmux *mux = data;
  82
  83         if (mux->data.idle_in_use)
  84                 return i2c_mux_reg_set(mux, mux->data.idle);
  85
  86         return 0;
  87 }
  88
  89 #ifdef CONFIG_OF
  90 static int i2c_mux_reg_probe_dt(struct regmux *mux,
  91                                         struct platform_device *pdev)
  92 {
  93         struct device_node *np = pdev->dev.of_node;
  94         struct device_node *adapter_np, *child;
  95         struct i2c_adapter *adapter;
  96         struct resource res;
  97         unsigned *values;
  98         int i = 0;
  99
 100         if (!np)
 101                 return -ENODEV;
 102
 103         adapter_np = of_parse_phandle(np, "i2c-parent", 0);
 104         if (!adapter_np) {
 105                 dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
 106                 return -ENODEV;
 107         }
 108         adapter = of_find_i2c_adapter_by_node(adapter_np);
 109         if (!adapter)
 110                 return -EPROBE_DEFER;
 111
 112         mux->parent = adapter;
 113         mux->data.parent = i2c_adapter_id(adapter);
 114         put_device(&adapter->dev);
 115
 116         mux->data.n_values = of_get_child_count(np);
 117         if (of_find_property(np, "little-endian", NULL)) {
 118                 mux->data.little_endian = true;
 119         } else if (of_find_property(np, "big-endian", NULL)) {
 120                 mux->data.little_endian = false;
 121         } else {
 122 #if defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : \
 123         defined(__LITTLE_ENDIAN)
 124                 mux->data.little_endian = true;
 125 #elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : \
 126         defined(__BIG_ENDIAN)
 127                 mux->data.little_endian = false;
 128 #else
 129 #error Endianness not defined?
 130 #endif
 131         }
 132         if (of_find_property(np, "write-only", NULL))
 133                 mux->data.write_only = true;
 134         else
 135                 mux->data.write_only = false;
 136
 137         values = devm_kzalloc(&pdev->dev,
 138                               sizeof(*mux->data.values) * mux->data.n_values,
 139                               GFP_KERNEL);
 140         if (!values) {
 141                 dev_err(&pdev->dev, "Cannot allocate values array");
 142                 return -ENOMEM;
 143         }
 144
 145         for_each_child_of_node(np, child) {
 146                 of_property_read_u32(child, "reg", values + i);
 147                 i++;
 148         }
 149         mux->data.values = values;
 150
 151         if (!of_property_read_u32(np, "idle-state", &mux->data.idle))
 152                 mux->data.idle_in_use = true;
 153
 154         /* map address from "reg" if exists */
 155         if (of_address_to_resource(np, 0, &res)) {
 156                 mux->data.reg_size = resource_size(&res);
 157                 if (mux->data.reg_size > 4) {
 158                         dev_err(&pdev->dev, "Invalid address size\n");
 159                         return -EINVAL;
 160                 }
 161                 mux->data.reg = devm_ioremap_resource(&pdev->dev, &res);
 162                 if (IS_ERR(mux->data.reg))
 163                         return PTR_ERR(mux->data.reg);
 164         }
 165
 166         return 0;
 167 }
 168 #else
 169 static int i2c_mux_reg_probe_dt(struct gpiomux *mux,
 170                                         struct platform_device *pdev)
 171 {
 172         return 0;
 173 }
 174 #endif
 175
 176 static int i2c_mux_reg_probe(struct platform_device *pdev)
 177 {
 178         struct regmux *mux;
 179         struct i2c_adapter *parent;
 180         struct resource *res;
 181         int (*deselect)(struct i2c_adapter *, void *, u32);
 182         unsigned int class;
 183         int i, ret, nr;
 184
 185         mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
 186         if (!mux)
 187                 return -ENOMEM;
 188
 189         platform_set_drvdata(pdev, mux);
 190
 191         if (dev_get_platdata(&pdev->dev)) {
 192                 memcpy(&mux->data, dev_get_platdata(&pdev->dev),
 193                         sizeof(mux->data));
 194
 195                 parent = i2c_get_adapter(mux->data.parent);
 196                 if (!parent)
 197                         return -EPROBE_DEFER;
 198
 199                 mux->parent = parent;
 200         } else {
 201                 ret = i2c_mux_reg_probe_dt(mux, pdev);
 202                 if (ret < 0) {
 203                         dev_err(&pdev->dev, "Error parsing device tree");
 204                         return ret;
 205                 }
 206         }
 207
 208         if (!mux->data.reg) {
 209                 dev_info(&pdev->dev,
 210                         "Register not set, using platform resource\n");
 211                 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 212                 mux->data.reg_size = resource_size(res);
 213                 if (mux->data.reg_size > 4) {
 214                         dev_err(&pdev->dev, "Invalid resource size\n");
 215                         return -EINVAL;
 216                 }
 217                 mux->data.reg = devm_ioremap_resource(&pdev->dev, res);
 218                 if (IS_ERR(mux->data.reg))
 219                         return PTR_ERR(mux->data.reg);
 220         }
 221
 222         mux->adap = devm_kzalloc(&pdev->dev,
 223                                  sizeof(*mux->adap) * mux->data.n_values,
 224                                  GFP_KERNEL);
 225         if (!mux->adap) {
 226                 dev_err(&pdev->dev, "Cannot allocate i2c_adapter structure");
 227                 return -ENOMEM;
 228         }
 229
 230         if (mux->data.idle_in_use)
 231                 deselect = i2c_mux_reg_deselect;
 232         else
 233                 deselect = NULL;
 234
 235         for (i = 0; i < mux->data.n_values; i++) {
 236                 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
 237                 class = mux->data.classes ? mux->data.classes[i] : 0;
 238
 239                 mux->adap[i] = i2c_add_mux_adapter(mux->parent, &pdev->dev, mux,
 240                                                    nr, mux->data.values[i],
 241                                                    class, i2c_mux_reg_select,
 242                                                    deselect);
 243                 if (!mux->adap[i]) {
 244                         ret = -ENODEV;
 245                         dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
 246                         goto add_adapter_failed;
 247                 }
 248         }
 249
 250         dev_dbg(&pdev->dev, "%d port mux on %s adapter\n",
 251                  mux->data.n_values, mux->parent->name);
 252
 253         return 0;
 254
 255 add_adapter_failed:
 256         for (; i > 0; i--)
 257                 i2c_del_mux_adapter(mux->adap[i - 1]);
 258
 259         return ret;
 260 }
 261
 262 static int i2c_mux_reg_remove(struct platform_device *pdev)
 263 {
 264         struct regmux *mux = platform_get_drvdata(pdev);
 265         int i;
 266
 267         for (i = 0; i < mux->data.n_values; i++)
 268                 i2c_del_mux_adapter(mux->adap[i]);
 269
 270         i2c_put_adapter(mux->parent);
 271
 272         return 0;
 273 }
 274
 275 static const struct of_device_id i2c_mux_reg_of_match[] = {
 276         { .compatible = "i2c-mux-reg", },
 277         {},
 278 };
 279 MODULE_DEVICE_TABLE(of, i2c_mux_reg_of_match);
 280
 281 static struct platform_driver i2c_mux_reg_driver = {
 282         .probe  = i2c_mux_reg_probe,
 283         .remove = i2c_mux_reg_remove,
 284         .driver = {
 285                 .name   = "i2c-mux-reg",
 286         },
 287 };
 288
 289 module_platform_driver(i2c_mux_reg_driver);
 290
 291 MODULE_DESCRIPTION("Register-based I2C multiplexer driver");
 292 MODULE_AUTHOR("York Sun <yorksun@freescale.com>");
 293 MODULE_LICENSE("GPL");
 294 MODULE_ALIAS("platform:i2c-mux-reg");