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                                 return dev_err_probe(dev, rc, "Cannot get address\n");
 110                 }
 111
 112                 i++;
 113         }
 114         mux->data.values = values;
 115
 116         if (device_property_read_u32(dev, "idle-state", &mux->data.idle))
 117                 mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
 118
 119         return 0;
 120 }
 121
 122 static int i2c_mux_gpio_probe(struct platform_device *pdev)
 123 {
 124         struct i2c_mux_core *muxc;
 125         struct gpiomux *mux;
 126         struct i2c_adapter *parent;
 127         struct i2c_adapter *root;
 128         unsigned initial_state;
 129         int i, ngpios, ret;
 130
 131         mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
 132         if (!mux)
 133                 return -ENOMEM;
 134
 135         if (!dev_get_platdata(&pdev->dev)) {
 136                 ret = i2c_mux_gpio_probe_fw(mux, pdev);
 137                 if (ret < 0)
 138                         return ret;
 139         } else {
 140                 memcpy(&mux->data, dev_get_platdata(&pdev->dev),
 141                         sizeof(mux->data));
 142         }
 143
 144         ngpios = gpiod_count(&pdev->dev, "mux");
 145         if (ngpios <= 0) {
 146                 dev_err(&pdev->dev, "no valid gpios provided\n");
 147                 return ngpios ?: -EINVAL;
 148         }
 149         mux->ngpios = ngpios;
 150
 151         parent = i2c_get_adapter(mux->data.parent);
 152         if (!parent)
 153                 return -EPROBE_DEFER;
 154
 155         muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
 156                              array_size(ngpios, sizeof(*mux->gpios)), 0,
 157                              i2c_mux_gpio_select, NULL);
 158         if (!muxc) {
 159                 ret = -ENOMEM;
 160                 goto alloc_failed;
 161         }
 162         mux->gpios = muxc->priv;
 163         muxc->priv = mux;
 164
 165         platform_set_drvdata(pdev, muxc);
 166
 167         root = i2c_root_adapter(&parent->dev);
 168
 169         muxc->mux_locked = true;
 170
 171         if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
 172                 initial_state = mux->data.idle;
 173                 muxc->deselect = i2c_mux_gpio_deselect;
 174         } else {
 175                 initial_state = mux->data.values[0];
 176         }
 177
 178         for (i = 0; i < ngpios; i++) {
 179                 struct device *gpio_dev;
 180                 struct gpio_desc *gpiod;
 181                 enum gpiod_flags flag;
 182
 183                 if (initial_state & BIT(i))
 184                         flag = GPIOD_OUT_HIGH;
 185                 else
 186                         flag = GPIOD_OUT_LOW;
 187                 gpiod = devm_gpiod_get_index(&pdev->dev, "mux", i, flag);
 188                 if (IS_ERR(gpiod)) {
 189                         ret = PTR_ERR(gpiod);
 190                         goto alloc_failed;
 191                 }
 192
 193                 mux->gpios[i] = gpiod;
 194
 195                 if (!muxc->mux_locked)
 196                         continue;
 197
 198                 /* FIXME: find a proper way to access the GPIO device */
 199                 gpio_dev = &gpiod->gdev->dev;
 200                 muxc->mux_locked = i2c_root_adapter(gpio_dev) == root;
 201         }
 202
 203         if (muxc->mux_locked)
 204                 dev_info(&pdev->dev, "mux-locked i2c mux\n");
 205
 206         for (i = 0; i < mux->data.n_values; i++) {
 207                 u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
 208                 unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;
 209
 210                 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class);
 211                 if (ret)
 212                         goto add_adapter_failed;
 213         }
 214
 215         dev_info(&pdev->dev, "%d port mux on %s adapter\n",
 216                  mux->data.n_values, parent->name);
 217
 218         return 0;
 219
 220 add_adapter_failed:
 221         i2c_mux_del_adapters(muxc);
 222 alloc_failed:
 223         i2c_put_adapter(parent);
 224
 225         return ret;
 226 }
 227
 228 static int i2c_mux_gpio_remove(struct platform_device *pdev)
 229 {
 230         struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
 231
 232         i2c_mux_del_adapters(muxc);
 233         i2c_put_adapter(muxc->parent);
 234
 235         return 0;
 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 = 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");