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 "../../gpio/gpiolib.h"
  19 #include <linux/of_gpio.h>
  20
  21 struct gpiomux {
  22         struct i2c_mux_gpio_platform_data data;
  23         unsigned gpio_base;
  24         struct gpio_desc **gpios;
  25         int *values;
  26 };
  27
  28 static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
  29 {
  30         int i;
  31
  32         for (i = 0; i < mux->data.n_gpios; i++)
  33                 mux->values[i] = (val >> i) & 1;
  34
  35         gpiod_set_array_value_cansleep(mux->data.n_gpios,
  36                                        mux->gpios, mux->values);
  37 }
  38
  39 static int i2c_mux_gpio_select(struct i2c_mux_core *muxc, u32 chan)
  40 {
  41         struct gpiomux *mux = i2c_mux_priv(muxc);
  42
  43         i2c_mux_gpio_set(mux, chan);
  44
  45         return 0;
  46 }
  47
  48 static int i2c_mux_gpio_deselect(struct i2c_mux_core *muxc, u32 chan)
  49 {
  50         struct gpiomux *mux = i2c_mux_priv(muxc);
  51
  52         i2c_mux_gpio_set(mux, mux->data.idle);
  53
  54         return 0;
  55 }
  56
  57 static int match_gpio_chip_by_label(struct gpio_chip *chip,
  58                                               void *data)
  59 {
  60         return !strcmp(chip->label, data);
  61 }
  62
  63 #ifdef CONFIG_OF
  64 static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
  65                                         struct platform_device *pdev)
  66 {
  67         struct device_node *np = pdev->dev.of_node;
  68         struct device_node *adapter_np, *child;
  69         struct i2c_adapter *adapter;
  70         unsigned *values, *gpios;
  71         int i = 0, ret;
  72
  73         if (!np)
  74                 return -ENODEV;
  75
  76         adapter_np = of_parse_phandle(np, "i2c-parent", 0);
  77         if (!adapter_np) {
  78                 dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
  79                 return -ENODEV;
  80         }
  81         adapter = of_find_i2c_adapter_by_node(adapter_np);
  82         of_node_put(adapter_np);
  83         if (!adapter)
  84                 return -EPROBE_DEFER;
  85
  86         mux->data.parent = i2c_adapter_id(adapter);
  87         put_device(&adapter->dev);
  88
  89         mux->data.n_values = of_get_child_count(np);
  90
  91         values = devm_kzalloc(&pdev->dev,
  92                               sizeof(*mux->data.values) * mux->data.n_values,
  93                               GFP_KERNEL);
  94         if (!values) {
  95                 dev_err(&pdev->dev, "Cannot allocate values array");
  96                 return -ENOMEM;
  97         }
  98
  99         for_each_child_of_node(np, child) {
 100                 of_property_read_u32(child, "reg", values + i);
 101                 i++;
 102         }
 103         mux->data.values = values;
 104
 105         if (of_property_read_u32(np, "idle-state", &mux->data.idle))
 106                 mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
 107
 108         mux->data.n_gpios = of_gpio_named_count(np, "mux-gpios");
 109         if (mux->data.n_gpios < 0) {
 110                 dev_err(&pdev->dev, "Missing mux-gpios property in the DT.\n");
 111                 return -EINVAL;
 112         }
 113
 114         gpios = devm_kzalloc(&pdev->dev,
 115                              sizeof(*mux->data.gpios) * mux->data.n_gpios, GFP_KERNEL);
 116         if (!gpios) {
 117                 dev_err(&pdev->dev, "Cannot allocate gpios array");
 118                 return -ENOMEM;
 119         }
 120
 121         for (i = 0; i < mux->data.n_gpios; i++) {
 122                 ret = of_get_named_gpio(np, "mux-gpios", i);
 123                 if (ret < 0)
 124                         return ret;
 125                 gpios[i] = ret;
 126         }
 127
 128         mux->data.gpios = gpios;
 129
 130         return 0;
 131 }
 132 #else
 133 static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
 134                                         struct platform_device *pdev)
 135 {
 136         return 0;
 137 }
 138 #endif
 139
 140 static int i2c_mux_gpio_probe(struct platform_device *pdev)
 141 {
 142         struct i2c_mux_core *muxc;
 143         struct gpiomux *mux;
 144         struct i2c_adapter *parent;
 145         struct i2c_adapter *root;
 146         unsigned initial_state, gpio_base;
 147         int i, ret;
 148
 149         mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
 150         if (!mux)
 151                 return -ENOMEM;
 152
 153         if (!dev_get_platdata(&pdev->dev)) {
 154                 ret = i2c_mux_gpio_probe_dt(mux, pdev);
 155                 if (ret < 0)
 156                         return ret;
 157         } else {
 158                 memcpy(&mux->data, dev_get_platdata(&pdev->dev),
 159                         sizeof(mux->data));
 160         }
 161
 162         /*
 163          * If a GPIO chip name is provided, the GPIO pin numbers provided are
 164          * relative to its base GPIO number. Otherwise they are absolute.
 165          */
 166         if (mux->data.gpio_chip) {
 167                 struct gpio_chip *gpio;
 168
 169                 gpio = gpiochip_find(mux->data.gpio_chip,
 170                                      match_gpio_chip_by_label);
 171                 if (!gpio)
 172                         return -EPROBE_DEFER;
 173
 174                 gpio_base = gpio->base;
 175         } else {
 176                 gpio_base = 0;
 177         }
 178
 179         parent = i2c_get_adapter(mux->data.parent);
 180         if (!parent)
 181                 return -EPROBE_DEFER;
 182
 183         muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
 184                              mux->data.n_gpios * sizeof(*mux->gpios) +
 185                              mux->data.n_gpios * sizeof(*mux->values), 0,
 186                              i2c_mux_gpio_select, NULL);
 187         if (!muxc) {
 188                 ret = -ENOMEM;
 189                 goto alloc_failed;
 190         }
 191         mux->gpios = muxc->priv;
 192         mux->values = (int *)(mux->gpios + mux->data.n_gpios);
 193         muxc->priv = mux;
 194
 195         platform_set_drvdata(pdev, muxc);
 196
 197         root = i2c_root_adapter(&parent->dev);
 198
 199         muxc->mux_locked = true;
 200         mux->gpio_base = gpio_base;
 201
 202         if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
 203                 initial_state = mux->data.idle;
 204                 muxc->deselect = i2c_mux_gpio_deselect;
 205         } else {
 206                 initial_state = mux->data.values[0];
 207         }
 208
 209         for (i = 0; i < mux->data.n_gpios; i++) {
 210                 struct device *gpio_dev;
 211                 struct gpio_desc *gpio_desc;
 212
 213                 ret = gpio_request(gpio_base + mux->data.gpios[i], "i2c-mux-gpio");
 214                 if (ret) {
 215                         dev_err(&pdev->dev, "Failed to request GPIO %d\n",
 216                                 mux->data.gpios[i]);
 217                         goto err_request_gpio;
 218                 }
 219
 220                 ret = gpio_direction_output(gpio_base + mux->data.gpios[i],
 221                                             initial_state & (1 << i));
 222                 if (ret) {
 223                         dev_err(&pdev->dev,
 224                                 "Failed to set direction of GPIO %d to output\n",
 225                                 mux->data.gpios[i]);
 226                         i++;    /* gpio_request above succeeded, so must free */
 227                         goto err_request_gpio;
 228                 }
 229
 230                 gpio_desc = gpio_to_desc(gpio_base + mux->data.gpios[i]);
 231                 mux->gpios[i] = gpio_desc;
 232
 233                 if (!muxc->mux_locked)
 234                         continue;
 235
 236                 gpio_dev = &gpio_desc->gdev->dev;
 237                 muxc->mux_locked = i2c_root_adapter(gpio_dev) == root;
 238         }
 239
 240         if (muxc->mux_locked)
 241                 dev_info(&pdev->dev, "mux-locked i2c mux\n");
 242
 243         for (i = 0; i < mux->data.n_values; i++) {
 244                 u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
 245                 unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;
 246
 247                 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class);
 248                 if (ret)
 249                         goto add_adapter_failed;
 250         }
 251
 252         dev_info(&pdev->dev, "%d port mux on %s adapter\n",
 253                  mux->data.n_values, parent->name);
 254
 255         return 0;
 256
 257 add_adapter_failed:
 258         i2c_mux_del_adapters(muxc);
 259         i = mux->data.n_gpios;
 260 err_request_gpio:
 261         for (; i > 0; i--)
 262                 gpio_free(gpio_base + mux->data.gpios[i - 1]);
 263 alloc_failed:
 264         i2c_put_adapter(parent);
 265
 266         return ret;
 267 }
 268
 269 static int i2c_mux_gpio_remove(struct platform_device *pdev)
 270 {
 271         struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
 272         struct gpiomux *mux = i2c_mux_priv(muxc);
 273         int i;
 274
 275         i2c_mux_del_adapters(muxc);
 276
 277         for (i = 0; i < mux->data.n_gpios; i++)
 278                 gpio_free(mux->gpio_base + mux->data.gpios[i]);
 279
 280         i2c_put_adapter(muxc->parent);
 281
 282         return 0;
 283 }
 284
 285 static const struct of_device_id i2c_mux_gpio_of_match[] = {
 286         { .compatible = "i2c-mux-gpio", },
 287         {},
 288 };
 289 MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
 290
 291 static struct platform_driver i2c_mux_gpio_driver = {
 292         .probe  = i2c_mux_gpio_probe,
 293         .remove = i2c_mux_gpio_remove,
 294         .driver = {
 295                 .name   = "i2c-mux-gpio",
 296                 .of_match_table = i2c_mux_gpio_of_match,
 297         },
 298 };
 299
 300 module_platform_driver(i2c_mux_gpio_driver);
 301
 302 MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
 303 MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
 304 MODULE_LICENSE("GPL");
 305 MODULE_ALIAS("platform:i2c-mux-gpio");