[PATCH v6 02/14] usb: typec: tcpci: Add support when hidden tx registers are inaccessible

Badhri Jagan Sridharan
2020-09-01T02:59:42Z

TCPCI spec forbids direct access of TX_BUF_BYTE_x register.
The existing version of tcpci driver assumes that those registers
are directly addressible. Add support for tcpci chips which do
not support direct access to TX_BUF_BYTE_x registers. TX_BUF_BYTE_x
can only be accessed by I2C_WRITE_BYTE_COUNT.

Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
---
Changes since v1:
- Refactored the code to check for TX_BUF_BYTE_x_hidden as suggested by
Heikki.
- Not formatting the tcpci_pd_transmit to follow the 100 character/line
limit as suggested by Heikki. (Should be a separate change).
- Changing patch version to v6 to fix version number confusion.
---
drivers/usb/typec/tcpm/tcpci.c | 46 ++++++++++++++++++++++++++--------
drivers/usb/typec/tcpm/tcpci.h | 8 ++++++
2 files changed, 43 insertions(+), 11 deletions(-)

diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
index bd80e03b2b6f..7d36d5e2d3f7 100644
--- a/drivers/usb/typec/tcpm/tcpci.c
+++ b/drivers/usb/typec/tcpm/tcpci.c
@@ -330,23 +330,47 @@ static int tcpci_pd_transmit(struct tcpc_dev *tcpc,
int ret;

cnt = msg ? pd_header_cnt(header) * 4 : 0;
- ret = regmap_write(tcpci->regmap, TCPC_TX_BYTE_CNT, cnt + 2);
- if (ret < 0)
- return ret;
+ /**
+ * TCPCI spec forbids direct access of TCPC_TX_DATA.
+ * But, since some of the chipsets offer this capability,
+ * it's fair to support both.
+ */
+ if (tcpci->data->TX_BUF_BYTE_x_hidden) {
+ u8 buf[TCPC_TRANSMIT_BUFFER_MAX_LEN] = {0,};
+ u8 pos = 0;

- ret = tcpci_write16(tcpci, TCPC_TX_HDR, header);
- if (ret < 0)
- return ret;
+ /* Payload + header + TCPC_TX_BYTE_CNT */
+ buf[pos++] = cnt + 2;
+
+ if (msg)
+ memcpy(&buf[pos], &msg->header, sizeof(msg->header));
+
+ pos += sizeof(header);

- if (cnt > 0) {
- ret = regmap_raw_write(tcpci->regmap, TCPC_TX_DATA,
- &msg->payload, cnt);
+ if (cnt > 0)
+ memcpy(&buf[pos], msg->payload, cnt);
+
+ pos += cnt;
+ ret = regmap_raw_write(tcpci->regmap, TCPC_TX_BYTE_CNT, buf, pos);
+ if (ret < 0)
+ return ret;
+ } else {
+ ret = regmap_write(tcpci->regmap, TCPC_TX_BYTE_CNT, cnt + 2);
if (ret < 0)
return ret;
+
+ ret = tcpci_write16(tcpci, TCPC_TX_HDR, header);
+ if (ret < 0)
+ return ret;
+
+ if (cnt > 0) {
+ ret = regmap_raw_write(tcpci->regmap, TCPC_TX_DATA, &msg->payload, cnt);
+ if (ret < 0)
+ return ret;
+ }
}

- reg = (PD_RETRY_COUNT << TCPC_TRANSMIT_RETRY_SHIFT) |
- (type << TCPC_TRANSMIT_TYPE_SHIFT);
+ reg = (PD_RETRY_COUNT << TCPC_TRANSMIT_RETRY_SHIFT) | (type << TCPC_TRANSMIT_TYPE_SHIFT);
ret = regmap_write(tcpci->regmap, TCPC_TRANSMIT, reg);
if (ret < 0)
return ret;
diff --git a/drivers/usb/typec/tcpm/tcpci.h b/drivers/usb/typec/tcpm/tcpci.h
index fd26ca35814c..cf9d8b63adcb 100644
--- a/drivers/usb/typec/tcpm/tcpci.h
+++ b/drivers/usb/typec/tcpm/tcpci.h
@@ -128,9 +128,17 @@
#define TCPC_VBUS_VOLTAGE_ALARM_HI_CFG 0x76
#define TCPC_VBUS_VOLTAGE_ALARM_LO_CFG 0x78

+/* I2C_WRITE_BYTE_COUNT + 1 when TX_BUF_BYTE_x is only accessible I2C_WRITE_BYTE_COUNT */
+#define TCPC_TRANSMIT_BUFFER_MAX_LEN 31
+
+/*
+ * @TX_BUF_BYTE_x_hidden
+ * optional; Set when TX_BUF_BYTE_x can only be accessed through I2C_WRITE_BYTE_COUNT.
+ */
struct tcpci;
struct tcpci_data {
struct regmap *regmap;
+ unsigned char TX_BUF_BYTE_x_hidden:1;
int (*init)(struct tcpci *tcpci, struct tcpci_data *data);
int (*set_vconn)(struct tcpci *tcpci, struct tcpci_data *data,
bool enable);
--
2.28.0.402.g5ffc5be6b7-goog