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