pinctrl: tegra-xusb: Fix allocation of pins

Commit e5b3b2d9ed20 ("pinctrl: allows not to define the get_group_pins
operation") allows pin controllers not to register the get_group_pins()
function. However, a side-effect of not registering this function is
that pins are not allocated and potentially multiple devices could
attempt to configure the same pins [1]. Although this problem exists in
the pinctrl core, because only a few devices are impacted by this, fix
this for tegra-xusb by adding the get_group_pins() function.

Please note that in addition to adding the get_group_pins() functions
the pins/lanes for the tegra-xusb also need to be registered when
calling pinctrl_register(). This also allows the current pinmux state
to be viewed by the debugfs node "pinmux-pins" for the tegra-xusb pad
controller.

[1] http://www.spinics.net/lists/linux-gpio/msg05810.html

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-tegra-xusb.c

@@ -125,6 +125,21 @@ static const char *tegra_xusb_padctl_get_group_name(struct pinctrl_dev *pinctrl,
 	return padctl->soc->pins[group].name;
 }
 
+static int tegra_xusb_padctl_get_group_pins(struct pinctrl_dev *pinctrl,
+					    unsigned group,
+					    const unsigned **pins,
+					    unsigned *num_pins)
+{
+	/*
+	 * For the tegra-xusb pad controller groups are synonomous
+	 * with lanes/pins and there is always one lane/pin per group.
+	 */
+	*pins = &pinctrl->desc->pins[group].number;
+	*num_pins = 1;
+
+	return 0;
+}
+
 enum tegra_xusb_padctl_param {
 	TEGRA_XUSB_PADCTL_IDDQ,
 };
@@ -248,6 +263,7 @@ static int tegra_xusb_padctl_dt_node_to_map(struct pinctrl_dev *pinctrl,
 static const struct pinctrl_ops tegra_xusb_padctl_pinctrl_ops = {
 	.get_groups_count = tegra_xusb_padctl_get_groups_count,
 	.get_group_name = tegra_xusb_padctl_get_group_name,
+	.get_group_pins = tegra_xusb_padctl_get_group_pins,
 	.dt_node_to_map = tegra_xusb_padctl_dt_node_to_map,
 	.dt_free_map = pinctrl_utils_dt_free_map,
 };
@@ -898,6 +914,8 @@ static int tegra_xusb_padctl_probe(struct platform_device *pdev)
 
 	memset(&padctl->desc, 0, sizeof(padctl->desc));
 	padctl->desc.name = dev_name(padctl->dev);
+	padctl->desc.pins = tegra124_pins;
+	padctl->desc.npins = ARRAY_SIZE(tegra124_pins);
 	padctl->desc.pctlops = &tegra_xusb_padctl_pinctrl_ops;
 	padctl->desc.pmxops = &tegra_xusb_padctl_pinmux_ops;
 	padctl->desc.confops = &tegra_xusb_padctl_pinconf_ops;