usb: typec: tcpci: Add support when hidden tx registers are inaccessible

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.

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
Link: https://lore.kernel.org/r/20200901025927.3596190-3-badhri@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
index bd80e03..7d36d5e 100644 (file)
--- 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 fd26ca3..cf9d8b6 100644 (file)
--- 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);