[PATCH 2/8] usb: typec: altmode: add low level altmode configuration helper

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

In some obscure cases (Qualcomm PMIC Glink) altmode is completely
handled by the firmware. Linux does not get proper partner altmode info.
Instead we get the notification once the altmode is negotiated and
entered (or left). However even in such a case the driver has to switch
board components (muxes, switches and retimers) according to the altmode
selected by the hardware.

We can not use existing typec_altmode_enter() / typec_altmode_exit() /
typec_altmode_notify() functions in such a case, since there is no
corresponding partner's altmode instance.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/usb/typec/bus.c           | 34 ++++++++++++++++++++++++++++++++++
 include/linux/usb/typec_altmode.h |  3 +++
 2 files changed, 37 insertions(+)

diff --git a/drivers/usb/typec/bus.c b/drivers/usb/typec/bus.c
index 6ea103e1abae..68f3908401c6 100644
--- a/drivers/usb/typec/bus.c
+++ b/drivers/usb/typec/bus.c
@@ -67,6 +67,40 @@ static int typec_altmode_set_state(struct typec_altmode *adev,
 	return typec_altmode_set_switches(port_altmode, conf, data);
 }
 
+/**
+ * typec_altmode_set_port - set the altmode configuration
+ * @conf: Alternate mode specific configuration value
+ * @dVata: Alternate mode specific data
+ *
+ * This function allows configuring muxes and retimer for the selected altmode.
+ * This function may only be used by the special case drivers, that handle
+ * the altmode negotiation by the alternative means and thus have no
+ * corresponding typec_altmode instance for the parnter.
+ */
+int typec_altmode_set_port(struct typec_altmode *adev,
+			   unsigned long conf, void *data)
+{
+	bool is_port;
+	struct altmode *altmode;
+	int ret;
+
+	if (!adev)
+		return 0;
+
+	altmode = to_altmode(adev);
+	is_port = is_typec_port(adev->dev.parent);
+
+	if (altmode->partner || !is_port)
+		return -EINVAL;
+
+	ret = typec_altmode_set_switches(altmode, conf, data);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(typec_altmode_set_port);
+
 /* -------------------------------------------------------------------------- */
 /* Common API */
 
diff --git a/include/linux/usb/typec_altmode.h b/include/linux/usb/typec_altmode.h
index b3c0866ea70f..d78a9618bedf 100644
--- a/include/linux/usb/typec_altmode.h
+++ b/include/linux/usb/typec_altmode.h
@@ -77,6 +77,9 @@ int typec_altmode_notify(struct typec_altmode *altmode, unsigned long conf,
 const struct typec_altmode *
 typec_altmode_get_partner(struct typec_altmode *altmode);
 
+int typec_altmode_set_port(struct typec_altmode *altmode, unsigned long conf,
+			   void *data);
+
 /**
  * struct typec_cable_ops - Cable alternate mode operations vector
  * @enter: Operations to be executed with Enter Mode Command

-- 
2.39.2