[PATCH 2/2 v2] typec: tcpm: Only request matching pdos

[Badhri Jagan Sridharan]

At present, TCPM code assumes that local device supports
variable/batt pdos and always selects the pdo with highest
possible power within the board limit. This assumption
might not hold good for all devices. To overcome this,
this patch makes TCPM only accept a source_pdo when there is
a matching sink pdo.

For Fixed pdos: The voltage should match between the
incoming source_cap and the registered snk_pdo
For Variable/Batt pdos: The incoming source_cap voltage
range should fall within the registered snk_pdo's voltage
range.

Also, when the cap_mismatch bit is set, the max_power/current
should be set to the max_current/power of the sink_pdo.
This is according to:

"If the Capability Mismatch bit is set to one
The Maximum Operating Current/Power field may contain a value
larger than the maximum current/power offered in the Source
Capabilities messageâs PDO as referenced by the Object position field.
This enables the Sink to indicate that it requires more current/power
than is being offered. If the Sink requires a different voltage this
will be indicated by its Sink Capabilities message.

Signed-off-by: Badhri Jagan Sridharan <Badhri@xxxxxxxxxx>
---
Changelog since v1:
- rebased on top drivers/usb/typec/tcpm.c as suggested by
  gregkh@xxxxxxxxxxxxxxxxxxx
- renamed nr_snk_*_pdo as suggested by dan.carpenter@xxxxxxxxxx
- removed stale comment as suggested by linux@xxxxxxxxxxxx
- removed the tests for nr_snk_*_pdo as suggested by
  dan.carpenter@xxxxxxxxxx
- Fixed sytling as suggested by dan.carpenter@xxxxxxxxxx
- renamed tcpm_get_nr_type_pdos to nr_type_pdos as suggested by
  dan.carpenter@xxxxxxxxxx
- fixed nr_type_pdos as suggested by dan.carpenter@xxxxxxxxxx
- tcpm_pd_select_pdo now checks for all matching variable/batt pdos
  instead of the first matching one.

 drivers/usb/typec/tcpm.c | 155 ++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 120 insertions(+), 35 deletions(-)

diff --git a/drivers/usb/typec/tcpm.c b/drivers/usb/typec/tcpm.c
index 75deac3ee58d..62d6fad8602f 100644
--- a/drivers/usb/typec/tcpm.c
+++ b/drivers/usb/typec/tcpm.c
@@ -261,6 +261,9 @@ struct tcpm_port {
 	unsigned int nr_src_pdo;
 	u32 snk_pdo[PDO_MAX_OBJECTS];
 	unsigned int nr_snk_pdo;
+	unsigned int nr_fixed; /* number of fixed sink PDOs */
+	unsigned int nr_var; /* number of variable sink PDOs */
+	unsigned int nr_batt; /* number of battery sink PDOs */
 	u32 snk_vdo[VDO_MAX_OBJECTS];
 	unsigned int nr_snk_vdo;
 
@@ -1758,39 +1761,92 @@ static int tcpm_pd_check_request(struct tcpm_port *port)
 	return 0;
 }
 
-static int tcpm_pd_select_pdo(struct tcpm_port *port)
+static void tcpm_pd_evaluate_pdo(struct tcpm_port *port, int src_pdo_index,
+				 int snk_pdo_index, int *max_mw, int *max_mv,
+				 int *selected_src_pdo,
+				 int *matching_snk_pdo)
 {
-	unsigned int i, max_mw = 0, max_mv = 0;
+	unsigned int mv = 0, ma = 0, mw = 0;
+	u32 src_pdo = port->source_caps[src_pdo_index];
+	u32 snk_pdo = port->snk_pdo[snk_pdo_index];
+	enum pd_pdo_type type = pdo_type(src_pdo);
+
+	mv = (type == PDO_TYPE_FIXED) ? pdo_fixed_voltage(src_pdo) :
+					pdo_min_voltage(src_pdo);
+
+	if (type == PDO_TYPE_BATT) {
+		mw = min(pdo_max_power(src_pdo), pdo_max_power(snk_pdo));
+	} else {
+		ma = min(pdo_max_current(src_pdo), pdo_max_current(snk_pdo));
+		mw = ma * mv / 1000;
+	}
+
+	/* Perfer higher voltages if available */
+	if (mw > *max_mw || (mw == *max_mw && mv > *max_mv)) {
+		*selected_src_pdo = src_pdo_index;
+		*matching_snk_pdo = snk_pdo_index;
+		*max_mw = mw;
+		*max_mv = mv;
+	}
+}
+
+static int tcpm_pd_select_pdo(struct tcpm_port *port, int *sink_pdo)
+{
+	unsigned int i, j, max_mw = 0, max_mv = 0;
 	int ret = -EINVAL;
 
 	/*
-	 * Select the source PDO providing the most power while staying within
-	 * the board's voltage limits. Prefer PDO providing exp
+	 * Select the source PDO providing the most power which has a
+	 * matchig sink cap.
 	 */
 	for (i = 0; i < port->nr_source_caps; i++) {
 		u32 pdo = port->source_caps[i];
 		enum pd_pdo_type type = pdo_type(pdo);
-		unsigned int mv, ma, mw;
-
-		if (type == PDO_TYPE_FIXED)
-			mv = pdo_fixed_voltage(pdo);
-		else
-			mv = pdo_min_voltage(pdo);
-
-		if (type == PDO_TYPE_BATT) {
-			mw = pdo_max_power(pdo);
-		} else {
-			ma = min(pdo_max_current(pdo),
-				 port->max_snk_ma);
-			mw = ma * mv / 1000;
-		}
 
-		/* Perfer higher voltages if available */
-		if ((mw > max_mw || (mw == max_mw && mv > max_mv)) &&
-		    mv <= port->max_snk_mv) {
-			ret = i;
-			max_mw = mw;
-			max_mv = mv;
+		if (type == PDO_TYPE_FIXED) {
+			for (j = 0; j < port->nr_fixed; j++) {
+				if (pdo_fixed_voltage(pdo) ==
+				    pdo_fixed_voltage(port->snk_pdo[j])) {
+					tcpm_pd_evaluate_pdo(port, i, j,
+							     &max_mw, &max_mv,
+							     &ret, sink_pdo);
+					/* There could only be one fixed pdo
+					 * at a specific voltage level.
+					 * So breaking here.
+					 */
+					break;
+				}
+			}
+		} else if (type == PDO_TYPE_BATT) {
+			for (j = port->nr_fixed;
+			     j < port->nr_fixed +
+				 port->nr_batt;
+			     j++) {
+				if (pdo_min_voltage(pdo) >=
+				     pdo_min_voltage(port->snk_pdo[j]) &&
+				     pdo_max_voltage(pdo) <=
+				     pdo_max_voltage(port->snk_pdo[j])) {
+					tcpm_pd_evaluate_pdo(port, i, j,
+							     &max_mw, &max_mv,
+							     &ret, sink_pdo);
+				}
+			}
+		} else if (type == PDO_TYPE_VAR) {
+			for (j = port->nr_fixed +
+				 port->nr_batt;
+			     j < port->nr_fixed +
+				 port->nr_batt +
+				 port->nr_var;
+			     j++) {
+				if (pdo_min_voltage(pdo) >=
+				     pdo_min_voltage(port->snk_pdo[j]) &&
+				     pdo_max_voltage(pdo) <=
+				     pdo_max_voltage(port->snk_pdo[j])) {
+					tcpm_pd_evaluate_pdo(port, i, j,
+							     &max_mw, &max_mv,
+							     &ret, sink_pdo);
+				}
+			}
 		}
 	}
 
@@ -1802,13 +1858,14 @@ static int tcpm_pd_build_request(struct tcpm_port *port, u32 *rdo)
 	unsigned int mv, ma, mw, flags;
 	unsigned int max_ma, max_mw;
 	enum pd_pdo_type type;
-	int index;
-	u32 pdo;
+	int index, snk_pdo_index;
+	u32 pdo, matching_snk_pdo;
 
-	index = tcpm_pd_select_pdo(port);
+	index = tcpm_pd_select_pdo(port, &snk_pdo_index);
 	if (index < 0)
 		return -EINVAL;
 	pdo = port->source_caps[index];
+	matching_snk_pdo = port->snk_pdo[snk_pdo_index];
 	type = pdo_type(pdo);
 
 	if (type == PDO_TYPE_FIXED)
@@ -1816,26 +1873,32 @@ static int tcpm_pd_build_request(struct tcpm_port *port, u32 *rdo)
 	else
 		mv = pdo_min_voltage(pdo);
 
-	/* Select maximum available current within the board's power limit */
+	/* Select maximum available current within the sink pdo's limit */
 	if (type == PDO_TYPE_BATT) {
-		mw = pdo_max_power(pdo);
-		ma = 1000 * min(mw, port->max_snk_mw) / mv;
+		mw = min(pdo_max_power(pdo), pdo_max_power(matching_snk_pdo));
+		ma = 1000 * mw / mv;
 	} else {
 		ma = min(pdo_max_current(pdo),
-			 1000 * port->max_snk_mw / mv);
+			 pdo_max_current(matching_snk_pdo));
+		mw = ma * mv / 1000;
 	}
-	ma = min(ma, port->max_snk_ma);
 
 	flags = RDO_USB_COMM | RDO_NO_SUSPEND;
 
 	/* Set mismatch bit if offered power is less than operating power */
-	mw = ma * mv / 1000;
 	max_ma = ma;
 	max_mw = mw;
 	if (mw < port->operating_snk_mw) {
 		flags |= RDO_CAP_MISMATCH;
-		max_mw = port->operating_snk_mw;
-		max_ma = max_mw * 1000 / mv;
+		if (type == PDO_TYPE_BATT) {
+			if (pdo_max_power(matching_snk_pdo) >
+			    pdo_max_power(pdo))
+				max_mw = pdo_max_power(matching_snk_pdo);
+		} else {
+			if (pdo_max_current(matching_snk_pdo) >
+			    pdo_max_current(pdo))
+				max_ma = pdo_max_current(matching_snk_pdo);
+		}
 	}
 
 	tcpm_log(port, "cc=%d cc1=%d cc2=%d vbus=%d vconn=%s polarity=%d",
@@ -3586,6 +3649,19 @@ int tcpm_update_sink_capabilities(struct tcpm_port *port, const u32 *pdo,
 }
 EXPORT_SYMBOL_GPL(tcpm_update_sink_capabilities);
 
+static int nr_type_pdos(const u32 *pdo, unsigned int nr_pdo,
+				 enum pd_pdo_type type)
+{
+	int count = 0;
+	int i;
+
+	for (i = 0; i < nr_pdo; i++) {
+		if (pdo_type(pdo[i]) == type)
+			count++;
+	}
+	return count;
+}
+
 struct tcpm_port *tcpm_register_port(struct device *dev, struct tcpc_dev *tcpc)
 {
 	struct tcpm_port *port;
@@ -3631,6 +3707,15 @@ struct tcpm_port *tcpm_register_port(struct device *dev, struct tcpc_dev *tcpc)
 					  tcpc->config->nr_src_pdo);
 	port->nr_snk_pdo = tcpm_copy_pdos(port->snk_pdo, tcpc->config->snk_pdo,
 					  tcpc->config->nr_snk_pdo);
+	port->nr_fixed =  nr_type_pdos(port->snk_pdo,
+							port->nr_snk_pdo,
+							PDO_TYPE_FIXED);
+	port->nr_var = nr_type_pdos(port->snk_pdo,
+						     port->nr_snk_pdo,
+						     PDO_TYPE_VAR);
+	port->nr_batt = nr_type_pdos(port->snk_pdo,
+						      port->nr_snk_pdo,
+						      PDO_TYPE_BATT);
 	port->nr_snk_vdo = tcpm_copy_vdos(port->snk_vdo, tcpc->config->snk_vdo,
 					  tcpc->config->nr_snk_vdo);
 
-- 
2.14.2.920.gcf0c67979c-goog