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