Re: [PATCH v4 2/2] usb: typec: tcpm: Support non-PD mode

Guenter Roeck <linux@xxxxxxxxxxxx> · Thu, 29 Jul 2021 23:31:18 -0700

On 7/29/21 11:18 PM, Kyle Tso wrote:
Even if the Type-C controller supports PD, it is doable to disable PD
capabilities with the current state machine in TCPM. Without enabling RX
in low-level drivers and with skipping the power negotiation, the port
is eligible to be a non-PD Type-C port. Use new flags whose values are
populated from the device tree to decide the port PD capability. Adding
"pd-unsupported" property in device tree indicates that the port does
not support PD. If PD is not supported, the device tree property
"typec-power-opmode" shall be added to specify the advertised Rp value
if the port supports SRC role.

Signed-off-by: Kyle Tso <kyletso@xxxxxxxxxx>

Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>

---
changes since v3:
- commit msg updated
- removed unnecessary empty lines
- re-factored the code of reading device tree properties and the error
   handling
- removed unnecessay variable initialization
- modified the comments

  drivers/usb/typec/tcpm/tcpm.c | 87 +++++++++++++++++++++++++++--------
  1 file changed, 68 insertions(+), 19 deletions(-)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index 5b22a1c931a9..faea1bf9dce0 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -316,6 +316,7 @@ struct tcpm_port {
  	struct typec_partner *partner;
  
  	enum typec_cc_status cc_req;
+	enum typec_cc_status src_rp;	/* work only if pd_supported == false */
  
  	enum typec_cc_status cc1;
  	enum typec_cc_status cc2;
@@ -323,6 +324,7 @@ struct tcpm_port {
  
  	bool attached;
  	bool connected;
+	bool pd_supported;
  	enum typec_port_type port_type;
  
  	/*
@@ -815,6 +817,9 @@ static enum typec_cc_status tcpm_rp_cc(struct tcpm_port *port)
  	int nr_pdo = port->nr_src_pdo;
  	int i;
  
+	if (!port->pd_supported)
+		return port->src_rp;
+
  	/*
  	 * Search for first entry with matching voltage.
  	 * It should report the maximum supported current.
@@ -3568,9 +3573,11 @@ static int tcpm_src_attach(struct tcpm_port *port)
  	if (ret < 0)
  		return ret;
  
-	ret = port->tcpc->set_pd_rx(port->tcpc, true);
-	if (ret < 0)
-		goto out_disable_mux;
+	if (port->pd_supported) {
+		ret = port->tcpc->set_pd_rx(port->tcpc, true);
+		if (ret < 0)
+			goto out_disable_mux;
+	}
  
  	/*
  	 * USB Type-C specification, version 1.2,
@@ -3600,7 +3607,8 @@ static int tcpm_src_attach(struct tcpm_port *port)
  out_disable_vconn:
  	tcpm_set_vconn(port, false);
  out_disable_pd:
-	port->tcpc->set_pd_rx(port->tcpc, false);
+	if (port->pd_supported)
+		port->tcpc->set_pd_rx(port->tcpc, false);
  out_disable_mux:
  	tcpm_mux_set(port, TYPEC_STATE_SAFE, USB_ROLE_NONE,
  		     TYPEC_ORIENTATION_NONE);
@@ -3804,6 +3812,20 @@ static enum typec_pwr_opmode tcpm_get_pwr_opmode(enum typec_cc_status cc)
  	}
  }
  
+static enum typec_cc_status tcpm_pwr_opmode_to_rp(enum typec_pwr_opmode opmode)
+{
+	switch (opmode) {
+	case TYPEC_PWR_MODE_USB:
+		return TYPEC_CC_RP_DEF;
+	case TYPEC_PWR_MODE_1_5A:
+		return TYPEC_CC_RP_1_5;
+	case TYPEC_PWR_MODE_3_0A:
+	case TYPEC_PWR_MODE_PD:
+	default:
+		return TYPEC_CC_RP_3_0;
+	}
+}
+
  static void run_state_machine(struct tcpm_port *port)
  {
  	int ret;
@@ -3914,6 +3936,10 @@ static void run_state_machine(struct tcpm_port *port)
  		if (port->ams == POWER_ROLE_SWAP ||
  		    port->ams == FAST_ROLE_SWAP)
  			tcpm_ams_finish(port);
+		if (!port->pd_supported) {
+			tcpm_set_state(port, SRC_READY, 0);
+			break;
+		}
  		port->upcoming_state = SRC_SEND_CAPABILITIES;
  		tcpm_ams_start(port, POWER_NEGOTIATION);
  		break;
@@ -4161,7 +4187,10 @@ static void run_state_machine(struct tcpm_port *port)
  				current_lim = PD_P_SNK_STDBY_MW / 5;
  			tcpm_set_current_limit(port, current_lim, 5000);
  			tcpm_set_charge(port, true);
-			tcpm_set_state(port, SNK_WAIT_CAPABILITIES, 0);
+			if (!port->pd_supported)
+				tcpm_set_state(port, SNK_READY, 0);
+			else
+				tcpm_set_state(port, SNK_WAIT_CAPABILITIES, 0);
  			break;
  		}
  		/*
@@ -4389,7 +4418,8 @@ static void run_state_machine(struct tcpm_port *port)
  		tcpm_set_vbus(port, true);
  		if (port->ams == HARD_RESET)
  			tcpm_ams_finish(port);
-		port->tcpc->set_pd_rx(port->tcpc, true);
+		if (port->pd_supported)
+			port->tcpc->set_pd_rx(port->tcpc, true);
  		tcpm_set_attached_state(port, true);
  		tcpm_set_state(port, SRC_UNATTACHED, PD_T_PS_SOURCE_ON);
  		break;
@@ -5898,6 +5928,7 @@ EXPORT_SYMBOL_GPL(tcpm_tcpc_reset);
  static int tcpm_fw_get_caps(struct tcpm_port *port,
  			    struct fwnode_handle *fwnode)
  {
+	const char *opmode_str;
  	const char *cap_str;
  	int ret;
  	u32 mw, frs_current;
@@ -5932,22 +5963,37 @@ static int tcpm_fw_get_caps(struct tcpm_port *port,
  		return ret;
  	port->typec_caps.type = ret;
  	port->port_type = port->typec_caps.type;
+	port->pd_supported = !fwnode_property_read_bool(fwnode, "pd-unsupported");
  
  	port->slow_charger_loop = fwnode_property_read_bool(fwnode, "slow-charger-loop");
  	if (port->port_type == TYPEC_PORT_SNK)
  		goto sink;
  
-	/* Get source pdos */
-	ret = fwnode_property_count_u32(fwnode, "source-pdos");
-	if (ret <= 0)
-		return -EINVAL;
+	/* Get Source PDOs for the PD port or Source Rp value for the non-PD port */
+	if (port->pd_supported) {
+		ret = fwnode_property_count_u32(fwnode, "source-pdos");
+		if (ret == 0)
+			return -EINVAL;
+		else if (ret < 0)
+			return ret;
  
-	port->nr_src_pdo = min(ret, PDO_MAX_OBJECTS);
-	ret = fwnode_property_read_u32_array(fwnode, "source-pdos",
-					     port->src_pdo, port->nr_src_pdo);
-	if ((ret < 0) || tcpm_validate_caps(port, port->src_pdo,
-					    port->nr_src_pdo))
-		return -EINVAL;
+		port->nr_src_pdo = min(ret, PDO_MAX_OBJECTS);
+		ret = fwnode_property_read_u32_array(fwnode, "source-pdos",
+						     port->src_pdo, port->nr_src_pdo);
+		if (ret)
+			return ret;
+		ret = tcpm_validate_caps(port, port->src_pdo, port->nr_src_pdo);
+		if (ret)
+			return ret;
+	} else {
+		ret = fwnode_property_read_string(fwnode, "typec-power-opmode", &opmode_str);
+		if (ret)
+			return ret;
+		ret = typec_find_pwr_opmode(opmode_str);
+		if (ret < 0)
+			return ret;
+		port->src_rp = tcpm_pwr_opmode_to_rp(ret);
+	}
  
  	if (port->port_type == TYPEC_PORT_SRC)
  		return 0;
@@ -5961,6 +6007,11 @@ static int tcpm_fw_get_caps(struct tcpm_port *port,
  	if (port->typec_caps.prefer_role < 0)
  		return -EINVAL;
  sink:
+	port->self_powered = fwnode_property_read_bool(fwnode, "self-powered");
+
+	if (!port->pd_supported)
+		return 0;
+
  	/* Get sink pdos */
  	ret = fwnode_property_count_u32(fwnode, "sink-pdos");
  	if (ret <= 0)
@@ -5977,9 +6028,7 @@ static int tcpm_fw_get_caps(struct tcpm_port *port,
  		return -EINVAL;
  	port->operating_snk_mw = mw / 1000;
  
-	port->self_powered = fwnode_property_read_bool(fwnode, "self-powered");
-
-	/* FRS can only be supported byb DRP ports */
+	/* FRS can only be supported by DRP ports */
  	if (port->port_type == TYPEC_PORT_DRP) {
  		ret = fwnode_property_read_u32(fwnode, "new-source-frs-typec-current",
  					       &frs_current);








