Re: [PATCH] usb: typec: tcpm: tcpci: Make the driver be compatible with the TCPCI spec [Rev 2.0 Ver 1.0, October 2017]

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Hi,

On Mon, Dec 02, 2024 at 03:06:45AM +0000, Miao Zhu wrote:
> The tcpci driver doesn't fully follow the TCPCI spec even if
> it mentions this spec in its comments.
> - Add two flags into tcpci_data:
> 	RX_BUF_BYTE_x_hidden
> 	conn_present_capable
> - Following flags in tcpci_data are read from device tree in tcpci_probe.
> 	TX_BUF_BYTE_x_hidden
> 	RX_BUF_BYTE_x_hidden
> 	auto_discharge_disconnect
> 	vbus_vsafe0v
> The change makes the driver be compatible with the TCPCI spec and
> therefore won't impact existing HW.
> 
> Signed-off-by: Miao Zhu <Miao.Zhu@xxxxxxxxxxxx>
> ---
>  drivers/usb/typec/tcpm/tcpci.c | 115 +++++++++++++++++++++++++++------
>  include/linux/usb/tcpci.h      |  11 ++++
>  2 files changed, 106 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
> index ed32583829be..e4a885fa38b5 100644
> --- a/drivers/usb/typec/tcpm/tcpci.c
> +++ b/drivers/usb/typec/tcpm/tcpci.c
> @@ -453,19 +453,26 @@ static int tcpci_set_roles(struct tcpc_dev *tcpc, bool attached,
>  			   enum typec_role role, enum typec_data_role data)
>  {
>  	struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
> -	unsigned int reg;
> +	unsigned int reg = 0;
>  	int ret;
>  
> -	reg = FIELD_PREP(TCPC_MSG_HDR_INFO_REV, PD_REV20);
> -	if (role == TYPEC_SOURCE)
> -		reg |= TCPC_MSG_HDR_INFO_PWR_ROLE;
> -	if (data == TYPEC_HOST)
> -		reg |= TCPC_MSG_HDR_INFO_DATA_ROLE;
> +	if (attached) {
> +		reg = FIELD_PREP(TCPC_MSG_HDR_INFO_REV, PD_REV20);
> +		if (role == TYPEC_SOURCE)
> +			reg |= TCPC_MSG_HDR_INFO_PWR_ROLE;
> +		if (data == TYPEC_HOST)
> +			reg |= TCPC_MSG_HDR_INFO_DATA_ROLE;
> +	}
>  	ret = regmap_write(tcpci->regmap, TCPC_MSG_HDR_INFO, reg);
>  	if (ret < 0)
>  		return ret;
>  
> -	return 0;
> +	if (tcpci->data->conn_present_capable)
> +		return regmap_update_bits(tcpci->regmap, TCPC_CONFIG_STD_OUTPUT,
> +					TCPC_CONFIG_STD_OUTPUT_CON_PRES,
> +					attached ? TCPC_CONFIG_STD_OUTPUT_CON_PRES : 0);
> +	else
> +		return 0;
>  }
>  
>  static int tcpci_set_pd_rx(struct tcpc_dev *tcpc, bool enable)
> @@ -741,33 +748,86 @@ irqreturn_t tcpci_irq(struct tcpci *tcpci)
>  		struct pd_message msg;
>  		unsigned int cnt, payload_cnt;
>  		u16 header;
> +		unsigned int frame_type;
> +		enum tcpm_transmit_type rx_type;
>  
>  		regmap_read(tcpci->regmap, TCPC_RX_BYTE_CNT, &cnt);
>  		/*
>  		 * 'cnt' corresponds to READABLE_BYTE_COUNT in section 4.4.14
>  		 * of the TCPCI spec [Rev 2.0 Ver 1.0 October 2017] and is
>  		 * defined in table 4-36 as one greater than the number of
> -		 * bytes received. And that number includes the header. So:
> +		 * bytes received. And that number includes the header.
> +		 * In Section 4.4.14 of the TCPCI spec [Rev 2.0 Ver 1.0 October, 2017],
> +		 * the RECEIVE_BUFFER comprises of three sets of registers:
> +		 * READABLE_BYTE_COUNT, RX_BUF_FRAME_TYPE and RX_BUF_BYTE_x.
> +		 * These registers can only be accessed by reading at a common
> +		 * register address 0x30h.
>  		 */
> -		if (cnt > 3)
> -			payload_cnt = cnt - (1 + sizeof(msg.header));
> -		else
> -			payload_cnt = 0;
> +		if (tcpci->data->TX_BUF_BYTE_x_hidden) {

use RX_BUF_BYTE_x_hidden for RX?

> +			u8 buf[TCPC_RECEIVE_BUFFER_MAX_LEN] = {0,};
> +			u8 pos = 0;
> +
> +			/* Read the count and frame type in RECEIVE_BUFFER */
> +			regmap_raw_read(tcpci->regmap, TCPC_RX_BYTE_CNT, buf, 2);
> +			/* READABLE_BYTE_COUNT */
> +			cnt = buf[0];
> +			/* RX_BUF_FRAME_TYPE */
> +			frame_type = buf[1];
> +
> +			/* Read the content of the USB PD message in RECEIVE_BUFFER */
> +			regmap_raw_read(tcpci->regmap, TCPC_RX_BYTE_CNT, buf, cnt + 1);
> +
> +			pos += 2;
> +			memcpy(&msg.header, &buf[pos], sizeof(msg.header));
> +
> +			if (cnt > 3) {
> +				pos += sizeof(msg.header);
> +				payload_cnt = cnt - (1 + sizeof(msg.header));
> +				if (WARN_ON(payload_cnt > sizeof(msg.payload)))
> +					payload_cnt = sizeof(msg.payload);
> +				memcpy(&msg.payload, &buf[pos], payload_cnt);
> +			}
> +		} else {
> +			regmap_read(tcpci->regmap, TCPC_RX_BYTE_CNT, &cnt);
> +			/*
> +			 * 'cnt' corresponds to READABLE_BYTE_COUNT in section 4.4.14
> +			 * of the TCPCI spec [Rev 2.0 Ver 1.0 October 2017] and is
> +			 * defined in table 4-36 as one greater than the number of
> +			 * bytes received. And that number includes the header. So:
> +			 */
> +			if (cnt > 3)
> +				payload_cnt = cnt - (1 + sizeof(msg.header));
> +			else
> +				payload_cnt = 0;
>  
> -		tcpci_read16(tcpci, TCPC_RX_HDR, &header);
> -		msg.header = cpu_to_le16(header);
> +			regmap_read(tcpci->regmap, TCPC_RX_BUF_FRAME_TYPE, &frame_type);
>  
> -		if (WARN_ON(payload_cnt > sizeof(msg.payload)))
> -			payload_cnt = sizeof(msg.payload);
> +			tcpci_read16(tcpci, TCPC_RX_HDR, &header);
> +			msg.header = cpu_to_le16(header);
>  
> -		if (payload_cnt > 0)
> -			regmap_raw_read(tcpci->regmap, TCPC_RX_DATA,
> -					&msg.payload, payload_cnt);
> +			if (WARN_ON(payload_cnt > sizeof(msg.payload)))
> +				payload_cnt = sizeof(msg.payload);
> +
> +			if (payload_cnt > 0)
> +				regmap_raw_read(tcpci->regmap, TCPC_RX_DATA,
> +							&msg.payload, payload_cnt);
> +		}
>  
>  		/* Read complete, clear RX status alert bit */
>  		tcpci_write16(tcpci, TCPC_ALERT, TCPC_ALERT_RX_STATUS);
>  
> -		tcpm_pd_receive(tcpci->port, &msg, TCPC_TX_SOP);
> +		switch (frame_type) {
> +		case TCPC_RX_BUF_FRAME_TYPE_SOP1:
> +			rx_type = TCPC_TX_SOP_PRIME;
> +			break;
> +		case TCPC_RX_BUF_FRAME_TYPE_SOP:
> +			rx_type = TCPC_TX_SOP;
> +			break;
> +		default:
> +			rx_type = TCPC_TX_SOP;
> +			break;
> +		}
> +		tcpm_pd_receive(tcpci->port, &msg, rx_type);
>  	}
>  
>  	if (tcpci->data->vbus_vsafe0v && (status & TCPC_ALERT_EXTENDED_STATUS)) {
> @@ -916,6 +976,21 @@ static int tcpci_probe(struct i2c_client *client)
>  	if (err < 0)
>  		return err;
>  
> +	chip->data.TX_BUF_BYTE_x_hidden =
> +		device_property_read_bool(&client->dev, "TX_BUF_BYTE_x_hidden");
> +	chip->data.RX_BUF_BYTE_x_hidden =
> +		device_property_read_bool(&client->dev, "RX_BUF_BYTE_x_hidden");
> +	chip->data.auto_discharge_disconnect =
> +		device_property_read_bool(&client->dev, "auto_discharge_disconnect");
> +	chip->data.vbus_vsafe0v = device_property_read_bool(&client->dev, "vbus_vsafe0v");

Please also document these properties in dt-bindings.

> +
> +	err = tcpci_check_std_output_cap(chip->data.regmap,
> +					 TCPC_STD_OUTPUT_CAP_CONN_PRESENT);
> +	if (err < 0)
> +		return err;
> +
> +	chip->data.conn_present_capable = err;
> +
>  	err = tcpci_check_std_output_cap(chip->data.regmap,
>  					 TCPC_STD_OUTPUT_CAP_ORIENTATION);
>  	if (err < 0)
> diff --git a/include/linux/usb/tcpci.h b/include/linux/usb/tcpci.h
> index f7f5cfbdef12..0760187ea4b5 100644
> --- a/include/linux/usb/tcpci.h
> +++ b/include/linux/usb/tcpci.h
> @@ -50,6 +50,7 @@
>  #define TCPC_CONFIG_STD_OUTPUT_ORIENTATION_MASK		BIT(0)
>  #define TCPC_CONFIG_STD_OUTPUT_ORIENTATION_NORMAL	0
>  #define TCPC_CONFIG_STD_OUTPUT_ORIENTATION_FLIPPED	1
> +#define TCPC_CONFIG_STD_OUTPUT_CON_PRES		BIT(1)
>  
>  #define TCPC_TCPC_CTRL			0x19
>  #define TCPC_TCPC_CTRL_ORIENTATION	BIT(0)
> @@ -126,6 +127,7 @@
>  #define TCPC_STD_INPUT_CAP		0x28
>  #define TCPC_STD_OUTPUT_CAP		0x29
>  #define TCPC_STD_OUTPUT_CAP_ORIENTATION	BIT(0)
> +#define TCPC_STD_OUTPUT_CAP_CONN_PRESENT	BIT(1)
>  
>  #define TCPC_MSG_HDR_INFO		0x2e
>  #define TCPC_MSG_HDR_INFO_DATA_ROLE	BIT(3)
> @@ -167,6 +169,7 @@
>  
>  /* I2C_WRITE_BYTE_COUNT + 1 when TX_BUF_BYTE_x is only accessible I2C_WRITE_BYTE_COUNT */
>  #define TCPC_TRANSMIT_BUFFER_MAX_LEN		31
> +#define TCPC_RECEIVE_BUFFER_MAX_LEN		32
>  
>  #define tcpc_presenting_rd(reg, cc) \
>  	(!(TCPC_ROLE_CTRL_DRP & (reg)) && \
> @@ -177,6 +180,9 @@ struct tcpci;
>  /*
>   * @TX_BUF_BYTE_x_hidden:
>   *		optional; Set when TX_BUF_BYTE_x can only be accessed through I2C_WRITE_BYTE_COUNT.
> + * @RX_BUF_BYTE_x_hidden:
> + *		Optional; Set when READABLE_BYTE_COUNT, RX_BUF_FRAME_TYPE and RX_BUF_BYTE_x
> + *		can only be accessed through READABLE_BYTE_COUNT.
>   * @frs_sourcing_vbus:
>   *		Optional; Callback to perform chip specific operations when FRS
>   *		is sourcing vbus.
> @@ -204,6 +210,9 @@ struct tcpci;
>   *		swap following Discover Identity on SOP' occurs.
>   *		Return true when the TCPM is allowed to request a Vconn swap
>   *		after Discovery Identity on SOP.
> + * @conn_present_capable:
> + *		Optional; Enable setting the connection present
> + *		CONFIG_STANDARD_OUTPUT (0x18) bit1.
>   * @set_orientation:
>   *		Optional; Enable setting the connector orientation
>   *		CONFIG_STANDARD_OUTPUT (0x18) bit0.
> @@ -211,9 +220,11 @@ struct tcpci;
>  struct tcpci_data {
>  	struct regmap *regmap;
>  	unsigned char TX_BUF_BYTE_x_hidden:1;
> +	unsigned char RX_BUF_BYTE_x_hidden:1;
>  	unsigned char auto_discharge_disconnect:1;
>  	unsigned char vbus_vsafe0v:1;
>  	unsigned char cable_comm_capable:1;
> +	unsigned char conn_present_capable:1;
>  	unsigned char set_orientation:1;
>  
>  	int (*init)(struct tcpci *tcpci, struct tcpci_data *data);
> -- 
> 2.27.0
> 




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