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 <[email protected]>
   6  */
   7
   8 #include <linux/bits.h>
   9 #include <linux/delay.h>
  10 #include <linux/gpio/consumer.h>
  11 #include <linux/gpio/driver.h>
  12 #include <linux/i2c.h>
  13 #include <linux/i2c-mux.h>
  14 #include <linux/module.h>
  15 #include <linux/overflow.h>
  16 #include <linux/platform_data/i2c-mux-gpio.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/slab.h>
  19
  20 struct gpiomux {
  21         struct i2c_mux_gpio_platform_data data;
  22         int ngpios;
  23         struct gpio_desc **gpios;
  24 };
  25
  26 static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned int val)
  27 {
  28         DECLARE_BITMAP(values, BITS_PER_TYPE(val));
  29
  30         values[0] = val;
  31
  32         gpiod_set_array_value_cansleep(mux->ngpios, mux->gpios, NULL, values);
  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         if (mux->data.settle_time)
  42                 fsleep(mux->data.settle_time);
  43
  44         return 0;
  45 }
  46
  47 static int i2c_mux_gpio_deselect(struct i2c_mux_core *muxc, u32 chan)
  48 {
  49         struct gpiomux *mux = i2c_mux_priv(muxc);
  50
  51         i2c_mux_gpio_set(mux, mux->data.idle);
  52
  53         return 0;
  54 }
  55
  56 static int i2c_mux_gpio_probe_fw(struct gpiomux *mux,
  57                                  struct platform_device *pdev)
  58 {
  59         struct device *dev = &pdev->dev;
  60         struct fwnode_handle *fwnode = dev_fwnode(dev);
  61         struct device_node *np = dev->of_node;
  62         struct device_node *adapter_np;
  63         struct i2c_adapter *adapter = NULL;
  64         struct fwnode_handle *child;
  65         unsigned int *values;
  66         int rc, i = 0;
  67
  68         if (is_of_node(fwnode)) {
  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
  80         } else if (is_acpi_node(fwnode)) {
  81                 /*
  82                  * In ACPI land the mux should be a direct child of the i2c
  83                  * bus it muxes.
  84                  */
  85                 acpi_handle dev_handle = ACPI_HANDLE(dev->parent);
  86
  87                 adapter = i2c_acpi_find_adapter_by_handle(dev_handle);
  88         }
  89
  90         if (!adapter)
  91                 return -EPROBE_DEFER;
  92
  93         mux->data.parent = i2c_adapter_id(adapter);
  94         put_device(&adapter->dev);
  95
  96         mux->data.n_values = device_get_child_node_count(dev);
  97         values = devm_kcalloc(dev,
  98                               mux->data.n_values, sizeof(*mux->data.values),
  99                               GFP_KERNEL);
 100         if (!values) {
 101                 dev_err(dev, "Cannot allocate values array");
 102                 return -ENOMEM;
 103         }
 104
 105         device_for_each_child_node(dev, child) {
 106                 if (is_of_node(child)) {
 107                         fwnode_property_read_u32(child, "reg", values + i);
 108                 } else if (is_acpi_node(child)) {
 109                         rc = acpi_get_local_address(ACPI_HANDLE_FWNODE(child), values + i);
 110                         if (rc) {
 111                                 fwnode_handle_put(child);
 112                                 return dev_err_probe(dev, rc, "Cannot get address\n");
 113                         }
 114                 }
 115
 116                 i++;
 117         }
 118         mux->data.values = values;
 119
 120         if (device_property_read_u32(dev, "idle-state", &mux->data.idle))
 121                 mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
 122
 123         device_property_read_u32(dev, "settle-time-us", &mux->data.settle_time);
 124
 125         return 0;
 126 }
 127
 128 static int i2c_mux_gpio_probe(struct platform_device *pdev)
 129 {
 130         struct i2c_mux_core *muxc;
 131         struct gpiomux *mux;
 132         struct i2c_adapter *parent;
 133         struct i2c_adapter *root;
 134         unsigned int initial_state;
 135         int i, ngpios, ret;
 136
 137         mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
 138         if (!mux)
 139                 return -ENOMEM;
 140
 141         if (!dev_get_platdata(&pdev->dev)) {
 142                 ret = i2c_mux_gpio_probe_fw(mux, pdev);
 143                 if (ret < 0)
 144                         return ret;
 145         } else {
 146                 memcpy(&mux->data, dev_get_platdata(&pdev->dev),
 147                         sizeof(mux->data));
 148         }
 149
 150         ngpios = gpiod_count(&pdev->dev, "mux");
 151         if (ngpios <= 0) {
 152                 dev_err(&pdev->dev, "no valid gpios provided\n");
 153                 return ngpios ?: -EINVAL;
 154         }
 155         mux->ngpios = ngpios;
 156
 157         parent = i2c_get_adapter(mux->data.parent);
 158         if (!parent)
 159                 return -EPROBE_DEFER;
 160
 161         muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
 162                              array_size(ngpios, sizeof(*mux->gpios)), 0,
 163                              i2c_mux_gpio_select, NULL);
 164         if (!muxc) {
 165                 ret = -ENOMEM;
 166                 goto alloc_failed;
 167         }
 168         mux->gpios = muxc->priv;
 169         muxc->priv = mux;
 170
 171         platform_set_drvdata(pdev, muxc);
 172
 173         root = i2c_root_adapter(&parent->dev);
 174
 175         muxc->mux_locked = true;
 176
 177         if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
 178                 initial_state = mux->data.idle;
 179                 muxc->deselect = i2c_mux_gpio_deselect;
 180         } else {
 181                 initial_state = mux->data.values[0];
 182         }
 183
 184         for (i = 0; i < ngpios; i++) {
 185                 struct gpio_device *gdev;
 186                 struct device *dev;
 187                 struct gpio_desc *gpiod;
 188                 enum gpiod_flags flag;
 189
 190                 if (initial_state & BIT(i))
 191                         flag = GPIOD_OUT_HIGH;
 192                 else
 193                         flag = GPIOD_OUT_LOW;
 194                 gpiod = devm_gpiod_get_index(&pdev->dev, "mux", i, flag);
 195                 if (IS_ERR(gpiod)) {
 196                         ret = PTR_ERR(gpiod);
 197                         goto alloc_failed;
 198                 }
 199
 200                 mux->gpios[i] = gpiod;
 201
 202                 if (!muxc->mux_locked)
 203                         continue;
 204
 205                 gdev = gpiod_to_gpio_device(gpiod);
 206                 dev = gpio_device_to_device(gdev);
 207                 muxc->mux_locked = i2c_root_adapter(dev) == root;
 208         }
 209
 210         if (muxc->mux_locked)
 211                 dev_info(&pdev->dev, "mux-locked i2c mux\n");
 212
 213         for (i = 0; i < mux->data.n_values; i++) {
 214                 u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
 215
 216                 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i]);
 217                 if (ret)
 218                         goto add_adapter_failed;
 219         }
 220
 221         dev_info(&pdev->dev, "%d port mux on %s adapter\n",
 222                  mux->data.n_values, parent->name);
 223
 224         return 0;
 225
 226 add_adapter_failed:
 227         i2c_mux_del_adapters(muxc);
 228 alloc_failed:
 229         i2c_put_adapter(parent);
 230
 231         return ret;
 232 }
 233
 234 static void i2c_mux_gpio_remove(struct platform_device *pdev)
 235 {
 236         struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
 237
 238         i2c_mux_del_adapters(muxc);
 239         i2c_put_adapter(muxc->parent);
 240 }
 241
 242 static const struct of_device_id i2c_mux_gpio_of_match[] = {
 243         { .compatible = "i2c-mux-gpio", },
 244         {},
 245 };
 246 MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
 247
 248 static struct platform_driver i2c_mux_gpio_driver = {
 249         .probe  = i2c_mux_gpio_probe,
 250         .remove = i2c_mux_gpio_remove,
 251         .driver = {
 252                 .name   = "i2c-mux-gpio",
 253                 .of_match_table = i2c_mux_gpio_of_match,
 254         },
 255 };
 256
 257 module_platform_driver(i2c_mux_gpio_driver);
 258
 259 MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
 260 MODULE_AUTHOR("Peter Korsgaard <[email protected]>");
 261 MODULE_LICENSE("GPL");
 262 MODULE_ALIAS("platform:i2c-mux-gpio");