Re: [PATCH] usb: typec: tcpm: Create legacy PDOs for PD2 connection

From: Guenter Roeck
Date: Sat Jan 23 2021 - 15:03:33 EST


On 1/15/21 8:33 AM, Kyle Tso wrote:
> If the port partner is PD2, the PDOs of the local port should follow the
> format defined in PD2 Spec. Dynamically modify the pre-defined PD3 PDOs
> and transform them into PD2 format before sending them to the PD2 port
> partner.
>
> Signed-off-by: Kyle Tso <kyletso@xxxxxxxxxx>

I don't like this too much, but I don't have a better idea. Thus,

Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxx>

Guenter

> ---
> drivers/usb/typec/tcpm/tcpm.c | 62 +++++++++++++++++++++++++++++------
> include/linux/usb/pd.h | 1 +
> 2 files changed, 53 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index 22a85b396f69..1220ab1ed47d 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -911,13 +911,47 @@ static int tcpm_set_pwr_role(struct tcpm_port *port, enum typec_role role)
> return 0;
> }
>
> +/*
> + * Transform the PDO to be compliant to PD rev2.0.
> + * Return 0 if the PDO type is not defined in PD rev2.0.
> + * Otherwise, return the converted PDO.
> + */
> +static u32 tcpm_forge_legacy_pdo(struct tcpm_port *port, u32 pdo, enum typec_role role)
> +{
> + switch (pdo_type(pdo)) {
> + case PDO_TYPE_FIXED:
> + if (role == TYPEC_SINK)
> + return pdo & ~PDO_FIXED_FRS_CURR_MASK;
> + else
> + return pdo & ~PDO_FIXED_UNCHUNK_EXT;
> + case PDO_TYPE_VAR:
> + case PDO_TYPE_BATT:
> + return pdo;
> + case PDO_TYPE_APDO:
> + default:
> + return 0;
> + }
> +}
> +
> static int tcpm_pd_send_source_caps(struct tcpm_port *port)
> {
> struct pd_message msg;
> - int i;
> + u32 pdo;
> + unsigned int i, nr_pdo = 0;
>
> memset(&msg, 0, sizeof(msg));
> - if (!port->nr_src_pdo) {
> +
> + for (i = 0; i < port->nr_src_pdo; i++) {
> + if (port->negotiated_rev >= PD_REV30) {
> + msg.payload[nr_pdo++] = cpu_to_le32(port->src_pdo[i]);
> + } else {
> + pdo = tcpm_forge_legacy_pdo(port, port->src_pdo[i], TYPEC_SOURCE);
> + if (pdo)
> + msg.payload[nr_pdo++] = cpu_to_le32(pdo);
> + }
> + }
> +
> + if (!nr_pdo) {
> /* No source capabilities defined, sink only */
> msg.header = PD_HEADER_LE(PD_CTRL_REJECT,
> port->pwr_role,
> @@ -930,10 +964,8 @@ static int tcpm_pd_send_source_caps(struct tcpm_port *port)
> port->data_role,
> port->negotiated_rev,
> port->message_id,
> - port->nr_src_pdo);
> + nr_pdo);
> }
> - for (i = 0; i < port->nr_src_pdo; i++)
> - msg.payload[i] = cpu_to_le32(port->src_pdo[i]);
>
> return tcpm_pd_transmit(port, TCPC_TX_SOP, &msg);
> }
> @@ -941,10 +973,22 @@ static int tcpm_pd_send_source_caps(struct tcpm_port *port)
> static int tcpm_pd_send_sink_caps(struct tcpm_port *port)
> {
> struct pd_message msg;
> - int i;
> + u32 pdo;
> + unsigned int i, nr_pdo = 0;
>
> memset(&msg, 0, sizeof(msg));
> - if (!port->nr_snk_pdo) {
> +
> + for (i = 0; i < port->nr_snk_pdo; i++) {
> + if (port->negotiated_rev >= PD_REV30) {
> + msg.payload[nr_pdo++] = cpu_to_le32(port->snk_pdo[i]);
> + } else {
> + pdo = tcpm_forge_legacy_pdo(port, port->snk_pdo[i], TYPEC_SINK);
> + if (pdo)
> + msg.payload[nr_pdo++] = cpu_to_le32(pdo);
> + }
> + }
> +
> + if (!nr_pdo) {
> /* No sink capabilities defined, source only */
> msg.header = PD_HEADER_LE(PD_CTRL_REJECT,
> port->pwr_role,
> @@ -957,10 +1001,8 @@ static int tcpm_pd_send_sink_caps(struct tcpm_port *port)
> port->data_role,
> port->negotiated_rev,
> port->message_id,
> - port->nr_snk_pdo);
> + nr_pdo);
> }
> - for (i = 0; i < port->nr_snk_pdo; i++)
> - msg.payload[i] = cpu_to_le32(port->snk_pdo[i]);
>
> return tcpm_pd_transmit(port, TCPC_TX_SOP, &msg);
> }
> diff --git a/include/linux/usb/pd.h b/include/linux/usb/pd.h
> index bb9a782e1411..88f64bce5dea 100644
> --- a/include/linux/usb/pd.h
> +++ b/include/linux/usb/pd.h
> @@ -225,6 +225,7 @@ enum pd_pdo_type {
> #define PDO_FIXED_EXTPOWER BIT(27) /* Externally powered */
> #define PDO_FIXED_USB_COMM BIT(26) /* USB communications capable */
> #define PDO_FIXED_DATA_SWAP BIT(25) /* Data role swap supported */
> +#define PDO_FIXED_UNCHUNK_EXT BIT(24) /* Unchunked Extended Message supported (Source) */
> #define PDO_FIXED_FRS_CURR_MASK (BIT(24) | BIT(23)) /* FR_Swap Current (Sink) */
> #define PDO_FIXED_FRS_CURR_SHIFT 23
> #define PDO_FIXED_VOLT_SHIFT 10 /* 50mV units */
>