[PATCH RFC 8/8] platform/chrome: cros_ec_typec: Enforce priority-based mode selection

[Andrei Kuchynski <akuchynski@chromium.org>]

The driver sets mode_selection bit for each Alternate mode, thereby
preventing individual altmode drivers from activating their respective
modes. Once the registration of all Alternate Modes is complete, the driver
invokes typec_mode_selection_start to initiate the mode selection process
based on mode priorities.
The driver communicates the current Type-C mode to the mode selection
process via typec_altmode_state_update.

Signed-off-by: Andrei Kuchynski <akuchynski@chromium.org>
---
 drivers/platform/chrome/cros_ec_typec.c      | 47 +++++++++++++++-----
 drivers/platform/chrome/cros_typec_altmode.c |  8 +++-
 2 files changed, 42 insertions(+), 13 deletions(-)

diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
index c0806c562bb9..cd827b1822e2 100644
--- a/drivers/platform/chrome/cros_ec_typec.c
+++ b/drivers/platform/chrome/cros_ec_typec.c
@@ -27,6 +27,11 @@
 						BIT(DP_PIN_ASSIGN_D) | \
 						BIT(DP_PIN_ASSIGN_E)))
 
+/* Delay between mode entry/exit attempts, ms */
+static const unsigned int mode_selection_delay = 1000;
+/* Timeout for a mode entry attempt, ms */
+static const unsigned int mode_selection_timeout = 4000;
+
 static void cros_typec_role_switch_quirk(struct fwnode_handle *fwnode)
 {
 #ifdef CONFIG_ACPI
@@ -325,6 +330,7 @@ static void cros_typec_remove_partner(struct cros_typec_data *typec,
 	if (!port->partner)
 		return;
 
+	typec_mode_selection_delete(port->partner);
 	cros_typec_unregister_altmodes(typec, port_num, true);
 
 	typec_partner_set_usb_power_delivery(port->partner, NULL);
@@ -400,17 +406,6 @@ static int cros_typec_register_port_altmodes(struct cros_typec_data *typec,
 	struct typec_altmode_desc desc;
 	struct typec_altmode *amode;
 
-	/* All PD capable CrOS devices are assumed to support DP altmode. */
-	memset(&desc, 0, sizeof(desc));
-	desc.svid = USB_TYPEC_DP_SID;
-	desc.mode = USB_TYPEC_DP_MODE;
-	desc.vdo = DP_PORT_VDO;
-	amode = cros_typec_register_displayport(port, &desc,
-						typec->ap_driven_altmode);
-	if (IS_ERR(amode))
-		return PTR_ERR(amode);
-	port->port_altmode[CROS_EC_ALTMODE_DP] = amode;
-
 	/*
 	 * Register TBT compatibility alt mode. The EC will not enter the mode
 	 * if it doesn't support it and it will not enter automatically by
@@ -428,6 +423,17 @@ static int cros_typec_register_port_altmodes(struct cros_typec_data *typec,
 		port->port_altmode[CROS_EC_ALTMODE_TBT] = amode;
 	}
 
+	/* All PD capable CrOS devices are assumed to support DP altmode. */
+	memset(&desc, 0, sizeof(desc));
+	desc.svid = USB_TYPEC_DP_SID;
+	desc.mode = USB_TYPEC_DP_MODE;
+	desc.vdo = DP_PORT_VDO;
+	amode = cros_typec_register_displayport(port, &desc,
+						typec->ap_driven_altmode);
+	if (IS_ERR(amode))
+		return PTR_ERR(amode);
+	port->port_altmode[CROS_EC_ALTMODE_DP] = amode;
+
 	port->state.alt = NULL;
 	port->state.mode = TYPEC_STATE_USB;
 	port->state.data = NULL;
@@ -742,6 +748,7 @@ static int cros_typec_configure_mux(struct cros_typec_data *typec, int port_num,
 	enum typec_orientation orientation;
 	struct cros_typec_altmode_node *node;
 	int ret;
+	u16 active_svid = 0;
 
 	ret = cros_ec_cmd(typec->ec, 0, EC_CMD_USB_PD_MUX_INFO,
 			  &req, sizeof(req), &resp, sizeof(resp));
@@ -780,10 +787,13 @@ static int cros_typec_configure_mux(struct cros_typec_data *typec, int port_num,
 
 	if (port->mux_flags & USB_PD_MUX_USB4_ENABLED) {
 		ret = cros_typec_enable_usb4(typec, port_num, pd_ctrl);
+		active_svid = USB_TYPEC_USB4_SID;
 	} else if (port->mux_flags & USB_PD_MUX_TBT_COMPAT_ENABLED) {
 		ret = cros_typec_enable_tbt(typec, port_num, pd_ctrl);
+		active_svid = USB_TYPEC_TBT_SID;
 	} else if (port->mux_flags & USB_PD_MUX_DP_ENABLED) {
 		ret = cros_typec_enable_dp(typec, port_num, pd_ctrl);
+		active_svid = USB_TYPEC_DP_SID;
 	} else if (port->mux_flags & USB_PD_MUX_SAFE_MODE) {
 		ret = cros_typec_usb_safe_state(port);
 	} else if (port->mux_flags & USB_PD_MUX_USB_ENABLED) {
@@ -799,6 +809,9 @@ static int cros_typec_configure_mux(struct cros_typec_data *typec, int port_num,
 			port->mux_flags);
 	}
 
+	if (port->partner)
+		typec_altmode_state_update(port->partner, active_svid, ret);
+
 	/* Iterate all partner alt-modes and set the active alternate mode. */
 	list_for_each_entry(node, &port->partner_mode_list, list) {
 		typec_altmode_update_active(
@@ -899,6 +912,7 @@ static int cros_typec_register_altmodes(struct cros_typec_data *typec, int port_
 			memset(&desc, 0, sizeof(desc));
 			desc.svid = sop_disc->svids[i].svid;
 			desc.mode = j + 1;
+			desc.mode_selection = typec->ap_driven_altmode;
 			desc.vdo = sop_disc->svids[i].mode_vdo[j];
 
 			if (is_partner)
@@ -940,6 +954,17 @@ static int cros_typec_register_altmodes(struct cros_typec_data *typec, int port_
 		goto err_cleanup;
 	}
 
+	/* Once all partner alt-modes are added, we should also trigger
+	 * mode selection.
+	 */
+	if (is_partner && typec->ap_driven_altmode) {
+		ret = typec_mode_selection_start(port->partner,
+				mode_selection_delay, mode_selection_timeout);
+		if (ret < 0)
+			dev_err(typec->dev,
+				"Unable to run mode selection on port%d partner\n", port_num);
+	}
+
 	return 0;
 
 err_cleanup:
diff --git a/drivers/platform/chrome/cros_typec_altmode.c b/drivers/platform/chrome/cros_typec_altmode.c
index 557340b53af0..ee4f2a9dd68a 100644
--- a/drivers/platform/chrome/cros_typec_altmode.c
+++ b/drivers/platform/chrome/cros_typec_altmode.c
@@ -41,12 +41,16 @@ static void cros_typec_altmode_work(struct work_struct *work)
 {
 	struct cros_typec_altmode_data *data =
 		container_of(work, struct cros_typec_altmode_data, work);
+	int ret;
 
 	mutex_lock(&data->lock);
 
-	if (typec_altmode_vdm(data->alt, data->header, data->vdo_data,
-			      data->vdo_size))
+	ret = typec_altmode_vdm(data->alt, data->header, data->vdo_data,
+			      data->vdo_size);
+	if (ret) {
 		dev_err(&data->alt->dev, "VDM 0x%x failed\n", data->header);
+		typec_altmode_state_update(data->port->partner, data->sid, ret);
+	}
 
 	data->header = 0;
 	data->vdo_data = NULL;
-- 
2.52.0.158.g65b55ccf14-goog