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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * I2C multiplexer using GPIO API
   4  *
   5  * Peter Korsgaard <peter.korsgaard@barco.com>
   6  */
   7
   8 #include <linux/i2c.h>
   9 #include <linux/i2c-mux.h>
  10 #include <linux/platform_data/i2c-mux-gpio.h>
  11 #include <linux/platform_device.h>
  12 #include <linux/module.h>
  13 #include <linux/slab.h>
  14 #include <linux/bits.h>
  15 #include <linux/gpio/consumer.h>
  16 /* FIXME: stop poking around inside gpiolib */
  17 #include "../../gpio/gpiolib.h"
  18
  19 struct gpiomux {
  20         struct i2c_mux_gpio_platform_data data;
  21         int ngpios;
  22         struct gpio_desc **gpios;
  23 };
  24
  25 static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
  26 {
  27         DECLARE_BITMAP(values, BITS_PER_TYPE(val));
  28
  29         values[0] = val;
  30
  31         gpiod_set_array_value_cansleep(mux->ngpios, mux->gpios, NULL, values);
  32 }
  33
  34 static int i2c_mux_gpio_select(struct i2c_mux_core *muxc, u32 chan)
  35 {
  36         struct gpiomux *mux = i2c_mux_priv(muxc);
  37
  38         i2c_mux_gpio_set(mux, chan);
  39
  40         return 0;
  41 }
  42
  43 static int i2c_mux_gpio_deselect(struct i2c_mux_core *muxc, u32 chan)
  44 {
  45         struct gpiomux *mux = i2c_mux_priv(muxc);
  46
  47         i2c_mux_gpio_set(mux, mux->data.idle);
  48
  49         return 0;
  50 }
  51
  52 #ifdef CONFIG_ACPI
  53
  54 static int i2c_mux_gpio_get_acpi_adr(struct device *dev,
  55                                      struct fwnode_handle *fwdev,
  56                                      unsigned int *adr)
  57
  58 {
  59         unsigned long long adr64;
  60         acpi_status status;
  61
  62         status = acpi_evaluate_integer(ACPI_HANDLE_FWNODE(fwdev),
  63                                        METHOD_NAME__ADR,
  64                                        NULL, &adr64);
  65
  66         if (!ACPI_SUCCESS(status)) {
  67                 dev_err(dev, "Cannot get address\n");
  68                 return -EINVAL;
  69         }
  70
  71         *adr = adr64;
  72         if (*adr != adr64) {
  73                 dev_err(dev, "Address out of range\n");
  74                 return -ERANGE;
  75         }
  76
  77         return 0;
  78 }
  79
  80 #else
  81
  82 static int i2c_mux_gpio_get_acpi_adr(struct device *dev,
  83                                      struct fwnode_handle *fwdev,
  84                                      unsigned int *adr)
  85 {
  86         return -EINVAL;
  87 }
  88
  89 #endif
  90
  91 static int i2c_mux_gpio_probe_fw(struct gpiomux *mux,
  92                                  struct platform_device *pdev)
  93 {
  94         struct device *dev = &pdev->dev;
  95         struct device_node *np = dev->of_node;
  96         struct device_node *adapter_np;
  97         struct i2c_adapter *adapter = NULL;
  98         struct fwnode_handle *child;
  99         unsigned *values;
 100         int rc, i = 0;
 101
 102         if (is_of_node(dev->fwnode)) {
 103                 if (!np)
 104                         return -ENODEV;
 105
 106                 adapter_np = of_parse_phandle(np, "i2c-parent", 0);
 107                 if (!adapter_np) {
 108                         dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
 109                         return -ENODEV;
 110                 }
 111                 adapter = of_find_i2c_adapter_by_node(adapter_np);
 112                 of_node_put(adapter_np);
 113
 114         } else if (is_acpi_node(dev->fwnode)) {
 115                 /*
 116                  * In ACPI land the mux should be a direct child of the i2c
 117                  * bus it muxes.
 118                  */
 119                 acpi_handle dev_handle = ACPI_HANDLE(dev->parent);
 120
 121                 adapter = i2c_acpi_find_adapter_by_handle(dev_handle);
 122         }
 123
 124         if (!adapter)
 125                 return -EPROBE_DEFER;
 126
 127         mux->data.parent = i2c_adapter_id(adapter);
 128         put_device(&adapter->dev);
 129
 130         mux->data.n_values = device_get_child_node_count(dev);
 131         values = devm_kcalloc(dev,
 132                               mux->data.n_values, sizeof(*mux->data.values),
 133                               GFP_KERNEL);
 134         if (!values) {
 135                 dev_err(dev, "Cannot allocate values array");
 136                 return -ENOMEM;
 137         }
 138
 139         device_for_each_child_node(dev, child) {
 140                 if (is_of_node(child)) {
 141                         fwnode_property_read_u32(child, "reg", values + i);
 142
 143                 } else if (is_acpi_node(child)) {
 144                         rc = i2c_mux_gpio_get_acpi_adr(dev, child, values + i);
 145                         if (rc)
 146                                 return rc;
 147                 }
 148
 149                 i++;
 150         }
 151         mux->data.values = values;
 152
 153         if (fwnode_property_read_u32(dev->fwnode, "idle-state", &mux->data.idle))
 154                 mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
 155
 156         return 0;
 157 }
 158
 159 static int i2c_mux_gpio_probe(struct platform_device *pdev)
 160 {
 161         struct i2c_mux_core *muxc;
 162         struct gpiomux *mux;
 163         struct i2c_adapter *parent;
 164         struct i2c_adapter *root;
 165         unsigned initial_state;
 166         int i, ngpios, ret;
 167
 168         mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
 169         if (!mux)
 170                 return -ENOMEM;
 171
 172         if (!dev_get_platdata(&pdev->dev)) {
 173                 ret = i2c_mux_gpio_probe_fw(mux, pdev);
 174                 if (ret < 0)
 175                         return ret;
 176         } else {
 177                 memcpy(&mux->data, dev_get_platdata(&pdev->dev),
 178                         sizeof(mux->data));
 179         }
 180
 181         ngpios = gpiod_count(&pdev->dev, "mux");
 182         if (ngpios <= 0) {
 183                 dev_err(&pdev->dev, "no valid gpios provided\n");
 184                 return ngpios ?: -EINVAL;
 185         }
 186         mux->ngpios = ngpios;
 187
 188         parent = i2c_get_adapter(mux->data.parent);
 189         if (!parent)
 190                 return -EPROBE_DEFER;
 191
 192         muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
 193                              ngpios * sizeof(*mux->gpios), 0,
 194                              i2c_mux_gpio_select, NULL);
 195         if (!muxc) {
 196                 ret = -ENOMEM;
 197                 goto alloc_failed;
 198         }
 199         mux->gpios = muxc->priv;
 200         muxc->priv = mux;
 201
 202         platform_set_drvdata(pdev, muxc);
 203
 204         root = i2c_root_adapter(&parent->dev);
 205
 206         muxc->mux_locked = true;
 207
 208         if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
 209                 initial_state = mux->data.idle;
 210                 muxc->deselect = i2c_mux_gpio_deselect;
 211         } else {
 212                 initial_state = mux->data.values[0];
 213         }
 214
 215         for (i = 0; i < ngpios; i++) {
 216                 struct device *gpio_dev;
 217                 struct gpio_desc *gpiod;
 218                 enum gpiod_flags flag;
 219
 220                 if (initial_state & BIT(i))
 221                         flag = GPIOD_OUT_HIGH;
 222                 else
 223                         flag = GPIOD_OUT_LOW;
 224                 gpiod = devm_gpiod_get_index(&pdev->dev, "mux", i, flag);
 225                 if (IS_ERR(gpiod)) {
 226                         ret = PTR_ERR(gpiod);
 227                         goto alloc_failed;
 228                 }
 229
 230                 mux->gpios[i] = gpiod;
 231
 232                 if (!muxc->mux_locked)
 233                         continue;
 234
 235                 /* FIXME: find a proper way to access the GPIO device */
 236                 gpio_dev = &gpiod->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 alloc_failed:
 260         i2c_put_adapter(parent);
 261
 262         return ret;
 263 }
 264
 265 static int i2c_mux_gpio_remove(struct platform_device *pdev)
 266 {
 267         struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
 268
 269         i2c_mux_del_adapters(muxc);
 270         i2c_put_adapter(muxc->parent);
 271
 272         return 0;
 273 }
 274
 275 static const struct of_device_id i2c_mux_gpio_of_match[] = {
 276         { .compatible = "i2c-mux-gpio", },
 277         {},
 278 };
 279 MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
 280
 281 static struct platform_driver i2c_mux_gpio_driver = {
 282         .probe  = i2c_mux_gpio_probe,
 283         .remove = i2c_mux_gpio_remove,
 284         .driver = {
 285                 .name   = "i2c-mux-gpio",
 286                 .of_match_table = i2c_mux_gpio_of_match,
 287         },
 288 };
 289
 290 module_platform_driver(i2c_mux_gpio_driver);
 291
 292 MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
 293 MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
 294 MODULE_LICENSE("GPL");
 295 MODULE_ALIAS("platform:i2c-mux-gpio");