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>

1 files changed, 6 insertions, 4 deletions

diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
index f2dfe0d8fcce..8e4387235b69 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);