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