i2c-mux: Add support for device auto-detection

Let I2C bus segments behind multiplexers have a class. This allows for
device auto-detection on these segments. As long as parent segments
don't share the same class, it should be fine.

I implemented support in drivers i2c-mux-gpio and i2c-mux-pca954x. I
left i2c-mux-pca9541 and i2c-mux-pinctrl alone for the moment as I
don't know if this feature makes sense for the use cases of these
drivers.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Peter Korsgaard <peter.korsgaard@barco.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Michael Lawnick <ml.lawnick@gmx.de>
Cc: Rodolfo Giometti <giometti@linux.it>

8 files changed, 37 insertions, 7 deletions

diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
index 1038c381aea..d94e0ce7827 100644
--- a/drivers/i2c/i2c-mux.c
+++ b/drivers/i2c/i2c-mux.c
@@ -88,9 +88,23 @@ static u32 i2c_mux_functionality(struct i2c_adapter *adap)
         return parent->algo->functionality(parent);
 }
 
+/* Return all parent classes, merged */
+static unsigned int i2c_mux_parent_classes(struct i2c_adapter *parent)
+{
+        unsigned int class = 0;
+
+        do {
+                class |= parent->class;
+                parent = i2c_parent_is_i2c_adapter(parent);
+        } while (parent);
+
+        return class;
+}
+
 struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
                                 struct device *mux_dev,
                                 void *mux_priv, u32 force_nr, u32 chan_id,
+                                unsigned int class,
                                 int (*select) (struct i2c_adapter *,
                                                void *, u32),
                                 int (*deselect) (struct i2c_adapter *,
@@ -127,6 +141,14 @@ struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
         priv->adap.algo_data = priv;
         priv->adap.dev.parent = &parent->dev;
 
+        /* Sanity check on class */
+        if (i2c_mux_parent_classes(parent) & class)
+                dev_err(&parent->dev,
+                        "Segment %d behind mux can't share classes with ancestors\n",
+                        chan_id);
+        else
+                priv->adap.class = class;
+
         /*
          * Try to populate the mux adapter's of_node, expands to
          * nothing if !CONFIG_OF.
diff --git a/drivers/i2c/muxes/i2c-mux-gpio.c b/drivers/i2c/muxes/i2c-mux-gpio.c
index 68b1f8ec343..56889e00c76 100644
--- a/drivers/i2c/muxes/i2c-mux-gpio.c
+++ b/drivers/i2c/muxes/i2c-mux-gpio.c
@@ -104,8 +104,10 @@ static int __devinit i2c_mux_gpio_probe(struct platform_device *pdev)
 
         for (i = 0; i < pdata->n_values; i++) {
                 u32 nr = pdata->base_nr ? (pdata->base_nr + i) : 0;
+                unsigned int class = pdata->classes ? pdata->classes[i] : 0;
 
-                mux->adap[i] = i2c_add_mux_adapter(parent, &pdev->dev, mux, nr, i,
+                mux->adap[i] = i2c_add_mux_adapter(parent, &pdev->dev, mux, nr,
+                                                   i, class,
                                                    i2c_mux_gpio_select, deselect);
                 if (!mux->adap[i]) {
                         ret = -ENODEV;
diff --git a/drivers/i2c/muxes/i2c-mux-pca9541.c b/drivers/i2c/muxes/i2c-mux-pca9541.c
index f8f72f39e0b..f3b8f9a6a89 100644
--- a/drivers/i2c/muxes/i2c-mux-pca9541.c
+++ b/drivers/i2c/muxes/i2c-mux-pca9541.c
@@ -354,7 +354,7 @@ static int pca9541_probe(struct i2c_client *client,
         if (pdata)
                 force = pdata->modes[0].adap_id;
         data->mux_adap = i2c_add_mux_adapter(adap, &client->dev, client,
-                                             force, 0,
+                                             force, 0, 0,
                                              pca9541_select_chan,
                                              pca9541_release_chan);
 
diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
index f2dfe0d8fcc..8e4387235b6 100644
--- a/drivers/i2c/muxes/i2c-mux-pca954x.c
+++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
@@ -186,7 +186,7 @@ static int pca954x_probe(struct i2c_client *client,
 {
         struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
         struct pca954x_platform_data *pdata = client->dev.platform_data;
-        int num, force;
+        int num, force, class;
         struct pca954x *data;
         int ret = -ENODEV;
 
@@ -216,18 +216,20 @@ static int pca954x_probe(struct i2c_client *client,
         /* Now create an adapter for each channel */
         for (num = 0; num < chips[data->type].nchans; num++) {
                 force = 0;                        /* dynamic adap number */
+                class = 0;                        /* no class by default */
                 if (pdata) {
-                        if (num < pdata->num_modes)
+                        if (num < pdata->num_modes) {
                                 /* force static number */
                                 force = pdata->modes[num].adap_id;
-                        else
+                                class = pdata->modes[num].class;
+                        } else
                                 /* discard unconfigured channels */
                                 break;
                 }
 
                 data->virt_adaps[num] =
                         i2c_add_mux_adapter(adap, &client->dev, client,
-                                force, num, pca954x_select_chan,
+                                force, num, class, pca954x_select_chan,
                                 (pdata && pdata->modes[num].deselect_on_exit)
                                         ? pca954x_deselect_mux : NULL);
 
diff --git a/drivers/i2c/muxes/i2c-mux-pinctrl.c b/drivers/i2c/muxes/i2c-mux-pinctrl.c
index 46a66976347..5f097f309b9 100644
--- a/drivers/i2c/muxes/i2c-mux-pinctrl.c
+++ b/drivers/i2c/muxes/i2c-mux-pinctrl.c
@@ -221,7 +221,7 @@ static int __devinit i2c_mux_pinctrl_probe(struct platform_device *pdev)
                                 (mux->pdata->base_bus_num + i) : 0;
 
                 mux->busses[i] = i2c_add_mux_adapter(mux->parent, &pdev->dev,
-                                                     mux, bus, i,
+                                                     mux, bus, i, 0,
                                                      i2c_mux_pinctrl_select,
                                                      deselect);
                 if (!mux->busses[i]) {
diff --git a/include/linux/i2c-mux-gpio.h b/include/linux/i2c-mux-gpio.h
index a36343a37eb..4ea1cc7392b 100644
--- a/include/linux/i2c-mux-gpio.h
+++ b/include/linux/i2c-mux-gpio.h
@@ -21,6 +21,7 @@
  * @values: Array of bitmasks of GPIO settings (low/high) for each
  *      position
  * @n_values: Number of multiplexer positions (busses to instantiate)
+ * @classes: Optional I2C auto-detection classes
  * @gpios: Array of GPIO numbers used to control MUX
  * @n_gpios: Number of GPIOs used to control MUX
  * @idle: Bitmask to write to MUX when idle or GPIO_I2CMUX_NO_IDLE if not used
@@ -30,6 +31,7 @@ struct i2c_mux_gpio_platform_data {
         int base_nr;
         const unsigned *values;
         int n_values;
+        const unsigned *classes;
         const unsigned *gpios;
         int n_gpios;
         unsigned idle;
diff --git a/include/linux/i2c-mux.h b/include/linux/i2c-mux.h
index c7908383001..40cb05a97b4 100644
--- a/include/linux/i2c-mux.h
+++ b/include/linux/i2c-mux.h
@@ -36,6 +36,7 @@
 struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
                                 struct device *mux_dev,
                                 void *mux_priv, u32 force_nr, u32 chan_id,
+                                unsigned int class,
                                 int (*select) (struct i2c_adapter *,
                                                void *mux_dev, u32 chan_id),
                                 int (*deselect) (struct i2c_adapter *,
diff --git a/include/linux/i2c/pca954x.h b/include/linux/i2c/pca954x.h
index 28f1f8d5ab1..1712677d590 100644
--- a/include/linux/i2c/pca954x.h
+++ b/include/linux/i2c/pca954x.h
@@ -36,6 +36,7 @@
 struct pca954x_platform_mode {
         int             adap_id;
         unsigned int    deselect_on_exit:1;
+        unsigned int    class;
 };
 
 /* Per mux/switch data, used with i2c_register_board_info */