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

   1 /*
   2  * I2C multiplexer using GPIO API
   3  *
   4  * Peter Korsgaard <peter.korsgaard@barco.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/i2c.h>
  12 #include <linux/i2c-mux.h>
  13 #include <linux/i2c-mux-gpio.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/module.h>
  16 #include <linux/slab.h>
  17 #include <linux/gpio.h>
  18 #include <linux/of_gpio.h>
  19
  20 struct gpiomux {
  21         struct i2c_adapter *parent;
  22         struct i2c_adapter **adap; /* child busses */
  23         struct i2c_mux_gpio_platform_data data;
  24         unsigned gpio_base;
  25 };
  26
  27 static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
  28 {
  29         int i;
  30
  31         for (i = 0; i < mux->data.n_gpios; i++)
  32                 gpio_set_value_cansleep(mux->gpio_base + mux->data.gpios[i],
  33                                         val & (1 << i));
  34 }
  35
  36 static int i2c_mux_gpio_select(struct i2c_adapter *adap, void *data, u32 chan)
  37 {
  38         struct gpiomux *mux = data;
  39
  40         i2c_mux_gpio_set(mux, chan);
  41
  42         return 0;
  43 }
  44
  45 static int i2c_mux_gpio_deselect(struct i2c_adapter *adap, void *data, u32 chan)
  46 {
  47         struct gpiomux *mux = data;
  48
  49         i2c_mux_gpio_set(mux, mux->data.idle);
  50
  51         return 0;
  52 }
  53
  54 static int match_gpio_chip_by_label(struct gpio_chip *chip,
  55                                               void *data)
  56 {
  57         return !strcmp(chip->label, data);
  58 }
  59
  60 #ifdef CONFIG_OF
  61 static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
  62                                         struct platform_device *pdev)
  63 {
  64         struct device_node *np = pdev->dev.of_node;
  65         struct device_node *adapter_np, *child;
  66         struct i2c_adapter *adapter;
  67         unsigned *values, *gpios;
  68         int i = 0, ret;
  69
  70         if (!np)
  71                 return -ENODEV;
  72
  73         adapter_np = of_parse_phandle(np, "i2c-parent", 0);
  74         if (!adapter_np) {
  75                 dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
  76                 return -ENODEV;
  77         }
  78         adapter = of_find_i2c_adapter_by_node(adapter_np);
  79         if (!adapter)
  80                 return -EPROBE_DEFER;
  81
  82         mux->data.parent = i2c_adapter_id(adapter);
  83         put_device(&adapter->dev);
  84
  85         mux->data.n_values = of_get_child_count(np);
  86
  87         values = devm_kzalloc(&pdev->dev,
  88                               sizeof(*mux->data.values) * mux->data.n_values,
  89                               GFP_KERNEL);
  90         if (!values) {
  91                 dev_err(&pdev->dev, "Cannot allocate values array");
  92                 return -ENOMEM;
  93         }
  94
  95         for_each_child_of_node(np, child) {
  96                 of_property_read_u32(child, "reg", values + i);
  97                 i++;
  98         }
  99         mux->data.values = values;
 100
 101         if (of_property_read_u32(np, "idle-state", &mux->data.idle))
 102                 mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
 103
 104         mux->data.n_gpios = of_gpio_named_count(np, "mux-gpios");
 105         if (mux->data.n_gpios < 0) {
 106                 dev_err(&pdev->dev, "Missing mux-gpios property in the DT.\n");
 107                 return -EINVAL;
 108         }
 109
 110         gpios = devm_kzalloc(&pdev->dev,
 111                              sizeof(*mux->data.gpios) * mux->data.n_gpios, GFP_KERNEL);
 112         if (!gpios) {
 113                 dev_err(&pdev->dev, "Cannot allocate gpios array");
 114                 return -ENOMEM;
 115         }
 116
 117         for (i = 0; i < mux->data.n_gpios; i++) {
 118                 ret = of_get_named_gpio(np, "mux-gpios", i);
 119                 if (ret < 0)
 120                         return ret;
 121                 gpios[i] = ret;
 122         }
 123
 124         mux->data.gpios = gpios;
 125
 126         return 0;
 127 }
 128 #else
 129 static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
 130                                         struct platform_device *pdev)
 131 {
 132         return 0;
 133 }
 134 #endif
 135
 136 static int i2c_mux_gpio_probe(struct platform_device *pdev)
 137 {
 138         struct gpiomux *mux;
 139         struct i2c_adapter *parent;
 140         int (*deselect) (struct i2c_adapter *, void *, u32);
 141         unsigned initial_state, gpio_base;
 142         int i, ret;
 143
 144         mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
 145         if (!mux) {
 146                 dev_err(&pdev->dev, "Cannot allocate gpiomux structure");
 147                 return -ENOMEM;
 148         }
 149
 150         platform_set_drvdata(pdev, mux);
 151
 152         if (!dev_get_platdata(&pdev->dev)) {
 153                 ret = i2c_mux_gpio_probe_dt(mux, pdev);
 154                 if (ret < 0)
 155                         return ret;
 156         } else {
 157                 memcpy(&mux->data, dev_get_platdata(&pdev->dev),
 158                         sizeof(mux->data));
 159         }
 160
 161         /*
 162          * If a GPIO chip name is provided, the GPIO pin numbers provided are
 163          * relative to its base GPIO number. Otherwise they are absolute.
 164          */
 165         if (mux->data.gpio_chip) {
 166                 struct gpio_chip *gpio;
 167
 168                 gpio = gpiochip_find(mux->data.gpio_chip,
 169                                      match_gpio_chip_by_label);
 170                 if (!gpio)
 171                         return -EPROBE_DEFER;
 172
 173                 gpio_base = gpio->base;
 174         } else {
 175                 gpio_base = 0;
 176         }
 177
 178         parent = i2c_get_adapter(mux->data.parent);
 179         if (!parent)
 180                 return -EPROBE_DEFER;
 181
 182         mux->parent = parent;
 183         mux->gpio_base = gpio_base;
 184
 185         mux->adap = devm_kzalloc(&pdev->dev,
 186                                  sizeof(*mux->adap) * mux->data.n_values,
 187                                  GFP_KERNEL);
 188         if (!mux->adap) {
 189                 dev_err(&pdev->dev, "Cannot allocate i2c_adapter structure");
 190                 ret = -ENOMEM;
 191                 goto alloc_failed;
 192         }
 193
 194         if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
 195                 initial_state = mux->data.idle;
 196                 deselect = i2c_mux_gpio_deselect;
 197         } else {
 198                 initial_state = mux->data.values[0];
 199                 deselect = NULL;
 200         }
 201
 202         for (i = 0; i < mux->data.n_gpios; i++) {
 203                 ret = gpio_request(gpio_base + mux->data.gpios[i], "i2c-mux-gpio");
 204                 if (ret) {
 205                         dev_err(&pdev->dev, "Failed to request GPIO %d\n",
 206                                 mux->data.gpios[i]);
 207                         goto err_request_gpio;
 208                 }
 209
 210                 ret = gpio_direction_output(gpio_base + mux->data.gpios[i],
 211                                             initial_state & (1 << i));
 212                 if (ret) {
 213                         dev_err(&pdev->dev,
 214                                 "Failed to set direction of GPIO %d to output\n",
 215                                 mux->data.gpios[i]);
 216                         i++;    /* gpio_request above succeeded, so must free */
 217                         goto err_request_gpio;
 218                 }
 219         }
 220
 221         for (i = 0; i < mux->data.n_values; i++) {
 222                 u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
 223                 unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;
 224
 225                 mux->adap[i] = i2c_add_mux_adapter(parent, &pdev->dev, mux, nr,
 226                                                    mux->data.values[i], class,
 227                                                    i2c_mux_gpio_select, deselect);
 228                 if (!mux->adap[i]) {
 229                         ret = -ENODEV;
 230                         dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
 231                         goto add_adapter_failed;
 232                 }
 233         }
 234
 235         dev_info(&pdev->dev, "%d port mux on %s adapter\n",
 236                  mux->data.n_values, parent->name);
 237
 238         return 0;
 239
 240 add_adapter_failed:
 241         for (; i > 0; i--)
 242                 i2c_del_mux_adapter(mux->adap[i - 1]);
 243         i = mux->data.n_gpios;
 244 err_request_gpio:
 245         for (; i > 0; i--)
 246                 gpio_free(gpio_base + mux->data.gpios[i - 1]);
 247 alloc_failed:
 248         i2c_put_adapter(parent);
 249
 250         return ret;
 251 }
 252
 253 static int i2c_mux_gpio_remove(struct platform_device *pdev)
 254 {
 255         struct gpiomux *mux = platform_get_drvdata(pdev);
 256         int i;
 257
 258         for (i = 0; i < mux->data.n_values; i++)
 259                 i2c_del_mux_adapter(mux->adap[i]);
 260
 261         for (i = 0; i < mux->data.n_gpios; i++)
 262                 gpio_free(mux->gpio_base + mux->data.gpios[i]);
 263
 264         i2c_put_adapter(mux->parent);
 265
 266         return 0;
 267 }
 268
 269 static const struct of_device_id i2c_mux_gpio_of_match[] = {
 270         { .compatible = "i2c-mux-gpio", },
 271         {},
 272 };
 273 MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
 274
 275 static struct platform_driver i2c_mux_gpio_driver = {
 276         .probe  = i2c_mux_gpio_probe,
 277         .remove = i2c_mux_gpio_remove,
 278         .driver = {
 279                 .name   = "i2c-mux-gpio",
 280                 .of_match_table = i2c_mux_gpio_of_match,
 281         },
 282 };
 283
 284 module_platform_driver(i2c_mux_gpio_driver);
 285
 286 MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
 287 MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
 288 MODULE_LICENSE("GPL");
 289 MODULE_ALIAS("platform:i2c-mux-gpio");