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/overflow.h>
  11 #include <linux/platform_data/i2c-mux-gpio.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/module.h>
  14 #include <linux/slab.h>
  15 #include <linux/bits.h>
  16 #include <linux/gpio/consumer.h>
  17 /* FIXME: stop poking around inside gpiolib */
  18 #include "../../gpio/gpiolib.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 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         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 i2c_mux_gpio_probe_fw(struct gpiomux *mux,
  54                                  struct platform_device *pdev)
  55 {
  56         struct device *dev = &pdev->dev;
  57         struct fwnode_handle *fwnode = dev_fwnode(dev);
  58         struct device_node *np = dev->of_node;
  59         struct device_node *adapter_np;
  60         struct i2c_adapter *adapter = NULL;
  61         struct fwnode_handle *child;
  62         unsigned *values;
  63         int rc, i = 0;
  64
  65         if (is_of_node(fwnode)) {
  66                 if (!np)
  67                         return -ENODEV;
  68
  69                 adapter_np = of_parse_phandle(np, "i2c-parent", 0);
  70                 if (!adapter_np) {
  71                         dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
  72                         return -ENODEV;
  73                 }
  74                 adapter = of_find_i2c_adapter_by_node(adapter_np);
  75                 of_node_put(adapter_np);
  76
  77         } else if (is_acpi_node(fwnode)) {
  78                 /*
  79                  * In ACPI land the mux should be a direct child of the i2c
  80                  * bus it muxes.
  81                  */
  82                 acpi_handle dev_handle = ACPI_HANDLE(dev->parent);
  83
  84                 adapter = i2c_acpi_find_adapter_by_handle(dev_handle);
  85         }
  86
  87         if (!adapter)
  88                 return -EPROBE_DEFER;
  89
  90         mux->data.parent = i2c_adapter_id(adapter);
  91         put_device(&adapter->dev);
  92
  93         mux->data.n_values = device_get_child_node_count(dev);
  94         values = devm_kcalloc(dev,
  95                               mux->data.n_values, sizeof(*mux->data.values),
  96                               GFP_KERNEL);
  97         if (!values) {
  98                 dev_err(dev, "Cannot allocate values array");
  99                 return -ENOMEM;
 100         }
 101
 102         device_for_each_child_node(dev, child) {
 103                 if (is_of_node(child)) {
 104                         fwnode_property_read_u32(child, "reg", values + i);
 105
 106                 } else if (is_acpi_node(child)) {
 107                         rc = acpi_get_local_address(ACPI_HANDLE_FWNODE(child), values + i);
 108                         if (rc) {
 109                                 fwnode_handle_put(child);
 110                                 return dev_err_probe(dev, rc, "Cannot get address\n");
 111                         }
 112                 }
 113
 114                 i++;
 115         }
 116         mux->data.values = values;
 117
 118         if (device_property_read_u32(dev, "idle-state", &mux->data.idle))
 119                 mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
 120
 121         return 0;
 122 }
 123
 124 static int i2c_mux_gpio_probe(struct platform_device *pdev)
 125 {
 126         struct i2c_mux_core *muxc;
 127         struct gpiomux *mux;
 128         struct i2c_adapter *parent;
 129         struct i2c_adapter *root;
 130         unsigned initial_state;
 131         int i, ngpios, ret;
 132
 133         mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
 134         if (!mux)
 135                 return -ENOMEM;
 136
 137         if (!dev_get_platdata(&pdev->dev)) {
 138                 ret = i2c_mux_gpio_probe_fw(mux, pdev);
 139                 if (ret < 0)
 140                         return ret;
 141         } else {
 142                 memcpy(&mux->data, dev_get_platdata(&pdev->dev),
 143                         sizeof(mux->data));
 144         }
 145
 146         ngpios = gpiod_count(&pdev->dev, "mux");
 147         if (ngpios <= 0) {
 148                 dev_err(&pdev->dev, "no valid gpios provided\n");
 149                 return ngpios ?: -EINVAL;
 150         }
 151         mux->ngpios = ngpios;
 152
 153         parent = i2c_get_adapter(mux->data.parent);
 154         if (!parent)
 155                 return -EPROBE_DEFER;
 156
 157         muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
 158                              array_size(ngpios, sizeof(*mux->gpios)), 0,
 159                              i2c_mux_gpio_select, NULL);
 160         if (!muxc) {
 161                 ret = -ENOMEM;
 162                 goto alloc_failed;
 163         }
 164         mux->gpios = muxc->priv;
 165         muxc->priv = mux;
 166
 167         platform_set_drvdata(pdev, muxc);
 168
 169         root = i2c_root_adapter(&parent->dev);
 170
 171         muxc->mux_locked = true;
 172
 173         if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
 174                 initial_state = mux->data.idle;
 175                 muxc->deselect = i2c_mux_gpio_deselect;
 176         } else {
 177                 initial_state = mux->data.values[0];
 178         }
 179
 180         for (i = 0; i < ngpios; i++) {
 181                 struct device *gpio_dev;
 182                 struct gpio_desc *gpiod;
 183                 enum gpiod_flags flag;
 184
 185                 if (initial_state & BIT(i))
 186                         flag = GPIOD_OUT_HIGH;
 187                 else
 188                         flag = GPIOD_OUT_LOW;
 189                 gpiod = devm_gpiod_get_index(&pdev->dev, "mux", i, flag);
 190                 if (IS_ERR(gpiod)) {
 191                         ret = PTR_ERR(gpiod);
 192                         goto alloc_failed;
 193                 }
 194
 195                 mux->gpios[i] = gpiod;
 196
 197                 if (!muxc->mux_locked)
 198                         continue;
 199
 200                 /* FIXME: find a proper way to access the GPIO device */
 201                 gpio_dev = &gpiod->gdev->dev;
 202                 muxc->mux_locked = i2c_root_adapter(gpio_dev) == root;
 203         }
 204
 205         if (muxc->mux_locked)
 206                 dev_info(&pdev->dev, "mux-locked i2c mux\n");
 207
 208         for (i = 0; i < mux->data.n_values; i++) {
 209                 u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
 210                 unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;
 211
 212                 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class);
 213                 if (ret)
 214                         goto add_adapter_failed;
 215         }
 216
 217         dev_info(&pdev->dev, "%d port mux on %s adapter\n",
 218                  mux->data.n_values, parent->name);
 219
 220         return 0;
 221
 222 add_adapter_failed:
 223         i2c_mux_del_adapters(muxc);
 224 alloc_failed:
 225         i2c_put_adapter(parent);
 226
 227         return ret;
 228 }
 229
 230 static void i2c_mux_gpio_remove(struct platform_device *pdev)
 231 {
 232         struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
 233
 234         i2c_mux_del_adapters(muxc);
 235         i2c_put_adapter(muxc->parent);
 236 }
 237
 238 static const struct of_device_id i2c_mux_gpio_of_match[] = {
 239         { .compatible = "i2c-mux-gpio", },
 240         {},
 241 };
 242 MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
 243
 244 static struct platform_driver i2c_mux_gpio_driver = {
 245         .probe  = i2c_mux_gpio_probe,
 246         .remove_new = i2c_mux_gpio_remove,
 247         .driver = {
 248                 .name   = "i2c-mux-gpio",
 249                 .of_match_table = i2c_mux_gpio_of_match,
 250         },
 251 };
 252
 253 module_platform_driver(i2c_mux_gpio_driver);
 254
 255 MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
 256 MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
 257 MODULE_LICENSE("GPL");
 258 MODULE_ALIAS("platform:i2c-mux-gpio");