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/platform_data/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_kcalloc(&pdev->dev,
  92                               mux->data.n_values, sizeof(*mux->data.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_kcalloc(&pdev->dev,
 115                              mux->data.n_gpios, sizeof(*mux->data.gpios),
 116                              GFP_KERNEL);
 117         if (!gpios) {
 118                 dev_err(&pdev->dev, "Cannot allocate gpios array");
 119                 return -ENOMEM;
 120         }
 121
 122         for (i = 0; i < mux->data.n_gpios; i++) {
 123                 ret = of_get_named_gpio(np, "mux-gpios", i);
 124                 if (ret < 0)
 125                         return ret;
 126                 gpios[i] = ret;
 127         }
 128
 129         mux->data.gpios = gpios;
 130
 131         return 0;
 132 }
 133 #else
 134 static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
 135                                         struct platform_device *pdev)
 136 {
 137         return 0;
 138 }
 139 #endif
 140
 141 static int i2c_mux_gpio_probe(struct platform_device *pdev)
 142 {
 143         struct i2c_mux_core *muxc;
 144         struct gpiomux *mux;
 145         struct i2c_adapter *parent;
 146         struct i2c_adapter *root;
 147         unsigned initial_state, gpio_base;
 148         int i, ret;
 149
 150         mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
 151         if (!mux)
 152                 return -ENOMEM;
 153
 154         if (!dev_get_platdata(&pdev->dev)) {
 155                 ret = i2c_mux_gpio_probe_dt(mux, pdev);
 156                 if (ret < 0)
 157                         return ret;
 158         } else {
 159                 memcpy(&mux->data, dev_get_platdata(&pdev->dev),
 160                         sizeof(mux->data));
 161         }
 162
 163         /*
 164          * If a GPIO chip name is provided, the GPIO pin numbers provided are
 165          * relative to its base GPIO number. Otherwise they are absolute.
 166          */
 167         if (mux->data.gpio_chip) {
 168                 struct gpio_chip *gpio;
 169
 170                 gpio = gpiochip_find(mux->data.gpio_chip,
 171                                      match_gpio_chip_by_label);
 172                 if (!gpio)
 173                         return -EPROBE_DEFER;
 174
 175                 gpio_base = gpio->base;
 176         } else {
 177                 gpio_base = 0;
 178         }
 179
 180         parent = i2c_get_adapter(mux->data.parent);
 181         if (!parent)
 182                 return -EPROBE_DEFER;
 183
 184         muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
 185                              mux->data.n_gpios * sizeof(*mux->gpios) +
 186                              mux->data.n_gpios * sizeof(*mux->values), 0,
 187                              i2c_mux_gpio_select, NULL);
 188         if (!muxc) {
 189                 ret = -ENOMEM;
 190                 goto alloc_failed;
 191         }
 192         mux->gpios = muxc->priv;
 193         mux->values = (int *)(mux->gpios + mux->data.n_gpios);
 194         muxc->priv = mux;
 195
 196         platform_set_drvdata(pdev, muxc);
 197
 198         root = i2c_root_adapter(&parent->dev);
 199
 200         muxc->mux_locked = true;
 201         mux->gpio_base = gpio_base;
 202
 203         if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
 204                 initial_state = mux->data.idle;
 205                 muxc->deselect = i2c_mux_gpio_deselect;
 206         } else {
 207                 initial_state = mux->data.values[0];
 208         }
 209
 210         for (i = 0; i < mux->data.n_gpios; i++) {
 211                 struct device *gpio_dev;
 212                 struct gpio_desc *gpio_desc;
 213
 214                 ret = gpio_request(gpio_base + mux->data.gpios[i], "i2c-mux-gpio");
 215                 if (ret) {
 216                         dev_err(&pdev->dev, "Failed to request GPIO %d\n",
 217                                 mux->data.gpios[i]);
 218                         goto err_request_gpio;
 219                 }
 220
 221                 ret = gpio_direction_output(gpio_base + mux->data.gpios[i],
 222                                             initial_state & (1 << i));
 223                 if (ret) {
 224                         dev_err(&pdev->dev,
 225                                 "Failed to set direction of GPIO %d to output\n",
 226                                 mux->data.gpios[i]);
 227                         i++;    /* gpio_request above succeeded, so must free */
 228                         goto err_request_gpio;
 229                 }
 230
 231                 gpio_desc = gpio_to_desc(gpio_base + mux->data.gpios[i]);
 232                 mux->gpios[i] = gpio_desc;
 233
 234                 if (!muxc->mux_locked)
 235                         continue;
 236
 237                 gpio_dev = &gpio_desc->gdev->dev;
 238                 muxc->mux_locked = i2c_root_adapter(gpio_dev) == root;
 239         }
 240
 241         if (muxc->mux_locked)
 242                 dev_info(&pdev->dev, "mux-locked i2c mux\n");
 243
 244         for (i = 0; i < mux->data.n_values; i++) {
 245                 u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
 246                 unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;
 247
 248                 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class);
 249                 if (ret)
 250                         goto add_adapter_failed;
 251         }
 252
 253         dev_info(&pdev->dev, "%d port mux on %s adapter\n",
 254                  mux->data.n_values, parent->name);
 255
 256         return 0;
 257
 258 add_adapter_failed:
 259         i2c_mux_del_adapters(muxc);
 260         i = mux->data.n_gpios;
 261 err_request_gpio:
 262         for (; i > 0; i--)
 263                 gpio_free(gpio_base + mux->data.gpios[i - 1]);
 264 alloc_failed:
 265         i2c_put_adapter(parent);
 266
 267         return ret;
 268 }
 269
 270 static int i2c_mux_gpio_remove(struct platform_device *pdev)
 271 {
 272         struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
 273         struct gpiomux *mux = i2c_mux_priv(muxc);
 274         int i;
 275
 276         i2c_mux_del_adapters(muxc);
 277
 278         for (i = 0; i < mux->data.n_gpios; i++)
 279                 gpio_free(mux->gpio_base + mux->data.gpios[i]);
 280
 281         i2c_put_adapter(muxc->parent);
 282
 283         return 0;
 284 }
 285
 286 static const struct of_device_id i2c_mux_gpio_of_match[] = {
 287         { .compatible = "i2c-mux-gpio", },
 288         {},
 289 };
 290 MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
 291
 292 static struct platform_driver i2c_mux_gpio_driver = {
 293         .probe  = i2c_mux_gpio_probe,
 294         .remove = i2c_mux_gpio_remove,
 295         .driver = {
 296                 .name   = "i2c-mux-gpio",
 297                 .of_match_table = i2c_mux_gpio_of_match,
 298         },
 299 };
 300
 301 module_platform_driver(i2c_mux_gpio_driver);
 302
 303 MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
 304 MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
 305 MODULE_LICENSE("GPL");
 306 MODULE_ALIAS("platform:i2c-mux-gpio");