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_OF
  53 static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
  54                                         struct platform_device *pdev)
  55 {
  56         struct device_node *np = pdev->dev.of_node;
  57         struct device_node *adapter_np, *child;
  58         struct i2c_adapter *adapter;
  59         unsigned *values;
  60         int i = 0;
  61
  62         if (!np)
  63                 return -ENODEV;
  64
  65         adapter_np = of_parse_phandle(np, "i2c-parent", 0);
  66         if (!adapter_np) {
  67                 dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
  68                 return -ENODEV;
  69         }
  70         adapter = of_find_i2c_adapter_by_node(adapter_np);
  71         of_node_put(adapter_np);
  72         if (!adapter)
  73                 return -EPROBE_DEFER;
  74
  75         mux->data.parent = i2c_adapter_id(adapter);
  76         put_device(&adapter->dev);
  77
  78         mux->data.n_values = of_get_child_count(np);
  79
  80         values = devm_kcalloc(&pdev->dev,
  81                               mux->data.n_values, sizeof(*mux->data.values),
  82                               GFP_KERNEL);
  83         if (!values) {
  84                 dev_err(&pdev->dev, "Cannot allocate values array");
  85                 return -ENOMEM;
  86         }
  87
  88         for_each_child_of_node(np, child) {
  89                 of_property_read_u32(child, "reg", values + i);
  90                 i++;
  91         }
  92         mux->data.values = values;
  93
  94         if (of_property_read_u32(np, "idle-state", &mux->data.idle))
  95                 mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
  96
  97         return 0;
  98 }
  99 #else
 100 static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
 101                                         struct platform_device *pdev)
 102 {
 103         return 0;
 104 }
 105 #endif
 106
 107 static int i2c_mux_gpio_probe(struct platform_device *pdev)
 108 {
 109         struct i2c_mux_core *muxc;
 110         struct gpiomux *mux;
 111         struct i2c_adapter *parent;
 112         struct i2c_adapter *root;
 113         unsigned initial_state;
 114         int i, ngpios, ret;
 115
 116         mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
 117         if (!mux)
 118                 return -ENOMEM;
 119
 120         if (!dev_get_platdata(&pdev->dev)) {
 121                 ret = i2c_mux_gpio_probe_dt(mux, pdev);
 122                 if (ret < 0)
 123                         return ret;
 124         } else {
 125                 memcpy(&mux->data, dev_get_platdata(&pdev->dev),
 126                         sizeof(mux->data));
 127         }
 128
 129         ngpios = gpiod_count(&pdev->dev, "mux");
 130         if (ngpios <= 0) {
 131                 dev_err(&pdev->dev, "no valid gpios provided\n");
 132                 return ngpios ?: -EINVAL;
 133         }
 134         mux->ngpios = ngpios;
 135
 136         parent = i2c_get_adapter(mux->data.parent);
 137         if (!parent)
 138                 return -EPROBE_DEFER;
 139
 140         muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
 141                              ngpios * sizeof(*mux->gpios), 0,
 142                              i2c_mux_gpio_select, NULL);
 143         if (!muxc) {
 144                 ret = -ENOMEM;
 145                 goto alloc_failed;
 146         }
 147         mux->gpios = muxc->priv;
 148         muxc->priv = mux;
 149
 150         platform_set_drvdata(pdev, muxc);
 151
 152         root = i2c_root_adapter(&parent->dev);
 153
 154         muxc->mux_locked = true;
 155
 156         if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
 157                 initial_state = mux->data.idle;
 158                 muxc->deselect = i2c_mux_gpio_deselect;
 159         } else {
 160                 initial_state = mux->data.values[0];
 161         }
 162
 163         for (i = 0; i < ngpios; i++) {
 164                 struct device *gpio_dev;
 165                 struct gpio_desc *gpiod;
 166                 enum gpiod_flags flag;
 167
 168                 if (initial_state & BIT(i))
 169                         flag = GPIOD_OUT_HIGH;
 170                 else
 171                         flag = GPIOD_OUT_LOW;
 172                 gpiod = devm_gpiod_get_index(&pdev->dev, "mux", i, flag);
 173                 if (IS_ERR(gpiod)) {
 174                         ret = PTR_ERR(gpiod);
 175                         goto alloc_failed;
 176                 }
 177
 178                 mux->gpios[i] = gpiod;
 179
 180                 if (!muxc->mux_locked)
 181                         continue;
 182
 183                 /* FIXME: find a proper way to access the GPIO device */
 184                 gpio_dev = &gpiod->gdev->dev;
 185                 muxc->mux_locked = i2c_root_adapter(gpio_dev) == root;
 186         }
 187
 188         if (muxc->mux_locked)
 189                 dev_info(&pdev->dev, "mux-locked i2c mux\n");
 190
 191         for (i = 0; i < mux->data.n_values; i++) {
 192                 u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
 193                 unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;
 194
 195                 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class);
 196                 if (ret)
 197                         goto add_adapter_failed;
 198         }
 199
 200         dev_info(&pdev->dev, "%d port mux on %s adapter\n",
 201                  mux->data.n_values, parent->name);
 202
 203         return 0;
 204
 205 add_adapter_failed:
 206         i2c_mux_del_adapters(muxc);
 207 alloc_failed:
 208         i2c_put_adapter(parent);
 209
 210         return ret;
 211 }
 212
 213 static int i2c_mux_gpio_remove(struct platform_device *pdev)
 214 {
 215         struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
 216
 217         i2c_mux_del_adapters(muxc);
 218         i2c_put_adapter(muxc->parent);
 219
 220         return 0;
 221 }
 222
 223 static const struct of_device_id i2c_mux_gpio_of_match[] = {
 224         { .compatible = "i2c-mux-gpio", },
 225         {},
 226 };
 227 MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
 228
 229 static struct platform_driver i2c_mux_gpio_driver = {
 230         .probe  = i2c_mux_gpio_probe,
 231         .remove = i2c_mux_gpio_remove,
 232         .driver = {
 233                 .name   = "i2c-mux-gpio",
 234                 .of_match_table = i2c_mux_gpio_of_match,
 235         },
 236 };
 237
 238 module_platform_driver(i2c_mux_gpio_driver);
 239
 240 MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
 241 MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
 242 MODULE_LICENSE("GPL");
 243 MODULE_ALIAS("platform:i2c-mux-gpio");