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

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * I2C multiplexer using a single register
   4  *
   5  * Copyright 2015 Freescale Semiconductor
   6  * York Sun  <yorksun@freescale.com>
   7  */
   8
   9 #include <linux/i2c.h>
  10 #include <linux/i2c-mux.h>
  11 #include <linux/init.h>
  12 #include <linux/io.h>
  13 #include <linux/module.h>
  14 #include <linux/of_address.h>
  15 #include <linux/platform_data/i2c-mux-reg.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/slab.h>
  18
  19 struct regmux {
  20         struct i2c_mux_reg_platform_data data;
  21 };
  22
  23 static int i2c_mux_reg_set(const struct regmux *mux, unsigned int chan_id)
  24 {
  25         if (!mux->data.reg)
  26                 return -EINVAL;
  27
  28         /*
  29          * Write to the register, followed by a read to ensure the write is
  30          * completed on a "posted" bus, for example PCI or write buffers.
  31          * The endianness of reading doesn't matter and the return data
  32          * is not used.
  33          */
  34         switch (mux->data.reg_size) {
  35         case 4:
  36                 if (mux->data.little_endian)
  37                         iowrite32(chan_id, mux->data.reg);
  38                 else
  39                         iowrite32be(chan_id, mux->data.reg);
  40                 if (!mux->data.write_only)
  41                         ioread32(mux->data.reg);
  42                 break;
  43         case 2:
  44                 if (mux->data.little_endian)
  45                         iowrite16(chan_id, mux->data.reg);
  46                 else
  47                         iowrite16be(chan_id, mux->data.reg);
  48                 if (!mux->data.write_only)
  49                         ioread16(mux->data.reg);
  50                 break;
  51         case 1:
  52                 iowrite8(chan_id, mux->data.reg);
  53                 if (!mux->data.write_only)
  54                         ioread8(mux->data.reg);
  55                 break;
  56         }
  57
  58         return 0;
  59 }
  60
  61 static int i2c_mux_reg_select(struct i2c_mux_core *muxc, u32 chan)
  62 {
  63         struct regmux *mux = i2c_mux_priv(muxc);
  64
  65         return i2c_mux_reg_set(mux, chan);
  66 }
  67
  68 static int i2c_mux_reg_deselect(struct i2c_mux_core *muxc, u32 chan)
  69 {
  70         struct regmux *mux = i2c_mux_priv(muxc);
  71
  72         if (mux->data.idle_in_use)
  73                 return i2c_mux_reg_set(mux, mux->data.idle);
  74
  75         return 0;
  76 }
  77
  78 #ifdef CONFIG_OF
  79 static int i2c_mux_reg_probe_dt(struct regmux *mux,
  80                                 struct platform_device *pdev)
  81 {
  82         struct device_node *np = pdev->dev.of_node;
  83         struct device_node *adapter_np, *child;
  84         struct i2c_adapter *adapter;
  85         struct resource res;
  86         unsigned *values;
  87         int i = 0;
  88
  89         if (!np)
  90                 return -ENODEV;
  91
  92         adapter_np = of_parse_phandle(np, "i2c-parent", 0);
  93         if (!adapter_np) {
  94                 dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
  95                 return -ENODEV;
  96         }
  97         adapter = of_find_i2c_adapter_by_node(adapter_np);
  98         of_node_put(adapter_np);
  99         if (!adapter)
 100                 return -EPROBE_DEFER;
 101
 102         mux->data.parent = i2c_adapter_id(adapter);
 103         put_device(&adapter->dev);
 104
 105         mux->data.n_values = of_get_child_count(np);
 106         if (of_property_read_bool(np, "little-endian")) {
 107                 mux->data.little_endian = true;
 108         } else if (of_property_read_bool(np, "big-endian")) {
 109                 mux->data.little_endian = false;
 110         } else {
 111 #if defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : \
 112         defined(__LITTLE_ENDIAN)
 113                 mux->data.little_endian = true;
 114 #elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : \
 115         defined(__BIG_ENDIAN)
 116                 mux->data.little_endian = false;
 117 #else
 118 #error Endianness not defined?
 119 #endif
 120         }
 121         mux->data.write_only = of_property_read_bool(np, "write-only");
 122
 123         values = devm_kcalloc(&pdev->dev,
 124                               mux->data.n_values, sizeof(*mux->data.values),
 125                               GFP_KERNEL);
 126         if (!values)
 127                 return -ENOMEM;
 128
 129         for_each_child_of_node(np, child) {
 130                 of_property_read_u32(child, "reg", values + i);
 131                 i++;
 132         }
 133         mux->data.values = values;
 134
 135         if (!of_property_read_u32(np, "idle-state", &mux->data.idle))
 136                 mux->data.idle_in_use = true;
 137
 138         /* map address from "reg" if exists */
 139         if (of_address_to_resource(np, 0, &res) == 0) {
 140                 mux->data.reg_size = resource_size(&res);
 141                 mux->data.reg = devm_ioremap_resource(&pdev->dev, &res);
 142                 if (IS_ERR(mux->data.reg))
 143                         return PTR_ERR(mux->data.reg);
 144         }
 145
 146         return 0;
 147 }
 148 #else
 149 static int i2c_mux_reg_probe_dt(struct regmux *mux,
 150                                 struct platform_device *pdev)
 151 {
 152         return 0;
 153 }
 154 #endif
 155
 156 static int i2c_mux_reg_probe(struct platform_device *pdev)
 157 {
 158         struct i2c_mux_core *muxc;
 159         struct regmux *mux;
 160         struct i2c_adapter *parent;
 161         struct resource *res;
 162         unsigned int class;
 163         int i, ret, nr;
 164
 165         mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
 166         if (!mux)
 167                 return -ENOMEM;
 168
 169         if (dev_get_platdata(&pdev->dev)) {
 170                 memcpy(&mux->data, dev_get_platdata(&pdev->dev),
 171                         sizeof(mux->data));
 172         } else {
 173                 ret = i2c_mux_reg_probe_dt(mux, pdev);
 174                 if (ret == -EPROBE_DEFER)
 175                         return ret;
 176
 177                 if (ret < 0) {
 178                         dev_err(&pdev->dev, "Error parsing device tree");
 179                         return ret;
 180                 }
 181         }
 182
 183         parent = i2c_get_adapter(mux->data.parent);
 184         if (!parent)
 185                 return -EPROBE_DEFER;
 186
 187         if (!mux->data.reg) {
 188                 dev_info(&pdev->dev,
 189                         "Register not set, using platform resource\n");
 190                 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 191                 mux->data.reg_size = resource_size(res);
 192                 mux->data.reg = devm_ioremap_resource(&pdev->dev, res);
 193                 if (IS_ERR(mux->data.reg)) {
 194                         ret = PTR_ERR(mux->data.reg);
 195                         goto err_put_parent;
 196                 }
 197         }
 198
 199         if (mux->data.reg_size != 4 && mux->data.reg_size != 2 &&
 200             mux->data.reg_size != 1) {
 201                 dev_err(&pdev->dev, "Invalid register size\n");
 202                 ret = -EINVAL;
 203                 goto err_put_parent;
 204         }
 205
 206         muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values, 0, 0,
 207                              i2c_mux_reg_select, NULL);
 208         if (!muxc) {
 209                 ret = -ENOMEM;
 210                 goto err_put_parent;
 211         }
 212         muxc->priv = mux;
 213
 214         platform_set_drvdata(pdev, muxc);
 215
 216         if (mux->data.idle_in_use)
 217                 muxc->deselect = i2c_mux_reg_deselect;
 218
 219         for (i = 0; i < mux->data.n_values; i++) {
 220                 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
 221                 class = mux->data.classes ? mux->data.classes[i] : 0;
 222
 223                 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class);
 224                 if (ret)
 225                         goto err_del_mux_adapters;
 226         }
 227
 228         dev_dbg(&pdev->dev, "%d port mux on %s adapter\n",
 229                  mux->data.n_values, muxc->parent->name);
 230
 231         return 0;
 232
 233 err_del_mux_adapters:
 234         i2c_mux_del_adapters(muxc);
 235 err_put_parent:
 236         i2c_put_adapter(parent);
 237
 238         return ret;
 239 }
 240
 241 static int i2c_mux_reg_remove(struct platform_device *pdev)
 242 {
 243         struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
 244
 245         i2c_mux_del_adapters(muxc);
 246         i2c_put_adapter(muxc->parent);
 247
 248         return 0;
 249 }
 250
 251 static const struct of_device_id i2c_mux_reg_of_match[] = {
 252         { .compatible = "i2c-mux-reg", },
 253         {},
 254 };
 255 MODULE_DEVICE_TABLE(of, i2c_mux_reg_of_match);
 256
 257 static struct platform_driver i2c_mux_reg_driver = {
 258         .probe  = i2c_mux_reg_probe,
 259         .remove = i2c_mux_reg_remove,
 260         .driver = {
 261                 .name   = "i2c-mux-reg",
 262                 .of_match_table = of_match_ptr(i2c_mux_reg_of_match),
 263         },
 264 };
 265
 266 module_platform_driver(i2c_mux_reg_driver);
 267
 268 MODULE_DESCRIPTION("Register-based I2C multiplexer driver");
 269 MODULE_AUTHOR("York Sun <yorksun@freescale.com>");
 270 MODULE_LICENSE("GPL");
 271 MODULE_ALIAS("platform:i2c-mux-reg");