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_mux_reg_platform_data data;
  25 };
  26
  27 static int i2c_mux_reg_set(const struct regmux *mux, unsigned int chan_id)
  28 {
  29         if (!mux->data.reg)
  30                 return -EINVAL;
  31
  32         /*
  33          * Write to the register, followed by a read to ensure the write is
  34          * completed on a "posted" bus, for example PCI or write buffers.
  35          * The endianness of reading doesn't matter and the return data
  36          * is not used.
  37          */
  38         switch (mux->data.reg_size) {
  39         case 4:
  40                 if (mux->data.little_endian)
  41                         iowrite32(chan_id, mux->data.reg);
  42                 else
  43                         iowrite32be(chan_id, mux->data.reg);
  44                 if (!mux->data.write_only)
  45                         ioread32(mux->data.reg);
  46                 break;
  47         case 2:
  48                 if (mux->data.little_endian)
  49                         iowrite16(chan_id, mux->data.reg);
  50                 else
  51                         iowrite16be(chan_id, mux->data.reg);
  52                 if (!mux->data.write_only)
  53                         ioread16(mux->data.reg);
  54                 break;
  55         case 1:
  56                 iowrite8(chan_id, mux->data.reg);
  57                 if (!mux->data.write_only)
  58                         ioread8(mux->data.reg);
  59                 break;
  60         }
  61
  62         return 0;
  63 }
  64
  65 static int i2c_mux_reg_select(struct i2c_mux_core *muxc, u32 chan)
  66 {
  67         struct regmux *mux = i2c_mux_priv(muxc);
  68
  69         return i2c_mux_reg_set(mux, chan);
  70 }
  71
  72 static int i2c_mux_reg_deselect(struct i2c_mux_core *muxc, u32 chan)
  73 {
  74         struct regmux *mux = i2c_mux_priv(muxc);
  75
  76         if (mux->data.idle_in_use)
  77                 return i2c_mux_reg_set(mux, mux->data.idle);
  78
  79         return 0;
  80 }
  81
  82 #ifdef CONFIG_OF
  83 static int i2c_mux_reg_probe_dt(struct regmux *mux,
  84                                 struct platform_device *pdev)
  85 {
  86         struct device_node *np = pdev->dev.of_node;
  87         struct device_node *adapter_np, *child;
  88         struct i2c_adapter *adapter;
  89         struct resource res;
  90         unsigned *values;
  91         int i = 0;
  92
  93         if (!np)
  94                 return -ENODEV;
  95
  96         adapter_np = of_parse_phandle(np, "i2c-parent", 0);
  97         if (!adapter_np) {
  98                 dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
  99                 return -ENODEV;
 100         }
 101         adapter = of_find_i2c_adapter_by_node(adapter_np);
 102         of_node_put(adapter_np);
 103         if (!adapter)
 104                 return -EPROBE_DEFER;
 105
 106         mux->data.parent = i2c_adapter_id(adapter);
 107         put_device(&adapter->dev);
 108
 109         mux->data.n_values = of_get_child_count(np);
 110         if (of_property_read_bool(np, "little-endian")) {
 111                 mux->data.little_endian = true;
 112         } else if (of_property_read_bool(np, "big-endian")) {
 113                 mux->data.little_endian = false;
 114         } else {
 115 #if defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : \
 116         defined(__LITTLE_ENDIAN)
 117                 mux->data.little_endian = true;
 118 #elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : \
 119         defined(__BIG_ENDIAN)
 120                 mux->data.little_endian = false;
 121 #else
 122 #error Endianness not defined?
 123 #endif
 124         }
 125         mux->data.write_only = of_property_read_bool(np, "write-only");
 126
 127         values = devm_kzalloc(&pdev->dev,
 128                               sizeof(*mux->data.values) * mux->data.n_values,
 129                               GFP_KERNEL);
 130         if (!values) {
 131                 dev_err(&pdev->dev, "Cannot allocate values array");
 132                 return -ENOMEM;
 133         }
 134
 135         for_each_child_of_node(np, child) {
 136                 of_property_read_u32(child, "reg", values + i);
 137                 i++;
 138         }
 139         mux->data.values = values;
 140
 141         if (!of_property_read_u32(np, "idle-state", &mux->data.idle))
 142                 mux->data.idle_in_use = true;
 143
 144         /* map address from "reg" if exists */
 145         if (of_address_to_resource(np, 0, &res) == 0) {
 146                 mux->data.reg_size = resource_size(&res);
 147                 mux->data.reg = devm_ioremap_resource(&pdev->dev, &res);
 148                 if (IS_ERR(mux->data.reg))
 149                         return PTR_ERR(mux->data.reg);
 150         }
 151
 152         return 0;
 153 }
 154 #else
 155 static int i2c_mux_reg_probe_dt(struct regmux *mux,
 156                                 struct platform_device *pdev)
 157 {
 158         return 0;
 159 }
 160 #endif
 161
 162 static int i2c_mux_reg_probe(struct platform_device *pdev)
 163 {
 164         struct i2c_mux_core *muxc;
 165         struct regmux *mux;
 166         struct i2c_adapter *parent;
 167         struct resource *res;
 168         unsigned int class;
 169         int i, ret, nr;
 170
 171         mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
 172         if (!mux)
 173                 return -ENOMEM;
 174
 175         if (dev_get_platdata(&pdev->dev)) {
 176                 memcpy(&mux->data, dev_get_platdata(&pdev->dev),
 177                         sizeof(mux->data));
 178         } else {
 179                 ret = i2c_mux_reg_probe_dt(mux, pdev);
 180                 if (ret == -EPROBE_DEFER)
 181                         return ret;
 182
 183                 if (ret < 0) {
 184                         dev_err(&pdev->dev, "Error parsing device tree");
 185                         return ret;
 186                 }
 187         }
 188
 189         parent = i2c_get_adapter(mux->data.parent);
 190         if (!parent)
 191                 return -EPROBE_DEFER;
 192
 193         if (!mux->data.reg) {
 194                 dev_info(&pdev->dev,
 195                         "Register not set, using platform resource\n");
 196                 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 197                 mux->data.reg_size = resource_size(res);
 198                 mux->data.reg = devm_ioremap_resource(&pdev->dev, res);
 199                 if (IS_ERR(mux->data.reg)) {
 200                         ret = PTR_ERR(mux->data.reg);
 201                         goto err_put_parent;
 202                 }
 203         }
 204
 205         if (mux->data.reg_size != 4 && mux->data.reg_size != 2 &&
 206             mux->data.reg_size != 1) {
 207                 dev_err(&pdev->dev, "Invalid register size\n");
 208                 ret = -EINVAL;
 209                 goto err_put_parent;
 210         }
 211
 212         muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values, 0, 0,
 213                              i2c_mux_reg_select, NULL);
 214         if (!muxc) {
 215                 ret = -ENOMEM;
 216                 goto err_put_parent;
 217         }
 218         muxc->priv = mux;
 219
 220         platform_set_drvdata(pdev, muxc);
 221
 222         if (mux->data.idle_in_use)
 223                 muxc->deselect = i2c_mux_reg_deselect;
 224
 225         for (i = 0; i < mux->data.n_values; i++) {
 226                 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
 227                 class = mux->data.classes ? mux->data.classes[i] : 0;
 228
 229                 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class);
 230                 if (ret)
 231                         goto err_del_mux_adapters;
 232         }
 233
 234         dev_dbg(&pdev->dev, "%d port mux on %s adapter\n",
 235                  mux->data.n_values, muxc->parent->name);
 236
 237         return 0;
 238
 239 err_del_mux_adapters:
 240         i2c_mux_del_adapters(muxc);
 241 err_put_parent:
 242         i2c_put_adapter(parent);
 243
 244         return ret;
 245 }
 246
 247 static int i2c_mux_reg_remove(struct platform_device *pdev)
 248 {
 249         struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
 250
 251         i2c_mux_del_adapters(muxc);
 252         i2c_put_adapter(muxc->parent);
 253
 254         return 0;
 255 }
 256
 257 static const struct of_device_id i2c_mux_reg_of_match[] = {
 258         { .compatible = "i2c-mux-reg", },
 259         {},
 260 };
 261 MODULE_DEVICE_TABLE(of, i2c_mux_reg_of_match);
 262
 263 static struct platform_driver i2c_mux_reg_driver = {
 264         .probe  = i2c_mux_reg_probe,
 265         .remove = i2c_mux_reg_remove,
 266         .driver = {
 267                 .name   = "i2c-mux-reg",
 268                 .of_match_table = of_match_ptr(i2c_mux_reg_of_match),
 269         },
 270 };
 271
 272 module_platform_driver(i2c_mux_reg_driver);
 273
 274 MODULE_DESCRIPTION("Register-based I2C multiplexer driver");
 275 MODULE_AUTHOR("York Sun <yorksun@freescale.com>");
 276 MODULE_LICENSE("GPL");
 277 MODULE_ALIAS("platform:i2c-mux-reg");