[PATCH v5 2/2] usb: typec: tcpm: Support non-PD mode

Kyle Tso
2021-07-30T12:46:06Z

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@google.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
---
Changes since v4:
- Added Reviewed-by

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);
--
2.32.0.554.ge1b32706d8-goog