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From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Date: Mon, 03 Jun 2024 02:24:57 +0300
Subject: [PATCH RFC 4/7] usb: typec: ucsi: rework command execution
 functions
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Message-Id: <20240603-ucsi-rework-interface-v1-4-99a6d544cec8@linaro.org>
References: <20240603-ucsi-rework-interface-v1-0-99a6d544cec8@linaro.org>
In-Reply-To: <20240603-ucsi-rework-interface-v1-0-99a6d544cec8@linaro.org>
To: Heikki Krogerus <heikki.krogerus@linux.intel.com>, 
 Greg Kroah-Hartman <gregkh@linuxfoundation.org>, 
 Maxime Coquelin <mcoquelin.stm32@gmail.com>, 
 Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: Nikita Travkin <nikita@trvn.ru>, 
 Neil Armstrong <neil.armstrong@linaro.org>, linux-usb@vger.kernel.org, 
 linux-kernel@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, 
 linux-arm-kernel@lists.infradead.org

Rework command execution code to remove recursive calls of
ucsi_exec_command. This also streamlines the sync_control / read(CCI)
read (MESSAGE_IN) sequence, allowing further rework of the command code.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/usb/typec/ucsi/ucsi.c | 134 ++++++++++++++++++++----------------------
 1 file changed, 64 insertions(+), 70 deletions(-)

diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
index a3a29ea4e325..54a2c505442f 100644
--- a/drivers/usb/typec/ucsi/ucsi.c
+++ b/drivers/usb/typec/ucsi/ucsi.c
@@ -63,25 +63,74 @@ static int ucsi_acknowledge(struct ucsi *ucsi, bool conn_ack)
 	return ucsi->ops->sync_control(ucsi, ctrl);
 }
 
-static int ucsi_exec_command(struct ucsi *ucsi, u64 command);
-
-static int ucsi_read_error(struct ucsi *ucsi)
+static int ucsi_run_command(struct ucsi *ucsi, u64 command, u32 *cci,
+			    void *data, size_t size, bool conn_ack)
 {
-	u16 error;
 	int ret;
 
-	ret = ucsi_exec_command(ucsi, UCSI_GET_ERROR_STATUS);
-	if (ret < 0)
+	*cci = 0;
+
+	ret = ucsi->ops->sync_control(ucsi, command);
+	if (ret)
 		return ret;
 
-	ret = ucsi_read_message_in(ucsi, &error, sizeof(error));
+	ret = ucsi->ops->read_cci(ucsi, cci);
 	if (ret)
 		return ret;
 
-	ret = ucsi_acknowledge(ucsi, false);
+	if (*cci & UCSI_CCI_BUSY)
+		return -EBUSY;
+
+	if (!(*cci & UCSI_CCI_COMMAND_COMPLETE))
+		return -EIO;
+
+	if (*cci & UCSI_CCI_NOT_SUPPORTED) {
+		if (ucsi_acknowledge(ucsi, false) < 0)
+			dev_err(ucsi->dev,
+				"ACK of unsupported command failed\n");
+		return -EOPNOTSUPP;
+	}
+
+	if (*cci & UCSI_CCI_ERROR) {
+		/* Acknowledge the command that failed */
+		ret = ucsi_acknowledge(ucsi, false);
+		return ret ? ret : -EIO;
+	}
+
+	if (data) {
+		ret = ucsi_read_message_in(ucsi, data, size);
+		if (ret)
+			return ret;
+	}
+
+	ret = ucsi_acknowledge(ucsi, conn_ack);
 	if (ret)
 		return ret;
 
+	return 0;
+}
+
+static int ucsi_read_error(struct ucsi *ucsi)
+{
+	u16 error;
+	u32 cci;
+	int ret;
+
+	ret = ucsi_run_command(ucsi, UCSI_GET_ERROR_STATUS, &cci,
+			       &error, sizeof(error), false);
+
+	if (cci & UCSI_CCI_BUSY) {
+		ret = ucsi_run_command(ucsi, UCSI_CANCEL, &cci, NULL, 0, false);
+
+		return ret ? ret : -EBUSY;
+	}
+
+	if (ret < 0)
+		return ret;
+
+	if (cci & UCSI_CCI_ERROR)
+		return -EIO;
+
 	switch (error) {
 	case UCSI_ERROR_INCOMPATIBLE_PARTNER:
 		return -EOPNOTSUPP;
@@ -121,78 +170,23 @@ static int ucsi_read_error(struct ucsi *ucsi)
 	return -EIO;
 }
 
-static int ucsi_exec_command(struct ucsi *ucsi, u64 cmd)
-{
-	u32 cci;
-	int ret;
-
-	ret = ucsi->ops->sync_control(ucsi, cmd);
-	if (ret)
-		return ret;
-
-	ret = ucsi->ops->read_cci(ucsi, &cci);
-	if (ret)
-		return ret;
-
-	if (cmd != UCSI_CANCEL && cci & UCSI_CCI_BUSY)
-		return ucsi_exec_command(ucsi, UCSI_CANCEL);
-
-	if (!(cci & UCSI_CCI_COMMAND_COMPLETE))
-		return -EIO;
-
-	if (cci & UCSI_CCI_NOT_SUPPORTED) {
-		if (ucsi_acknowledge(ucsi, false) < 0)
-			dev_err(ucsi->dev,
-				"ACK of unsupported command failed\n");
-		return -EOPNOTSUPP;
-	}
-
-	if (cci & UCSI_CCI_ERROR) {
-		/* Acknowledge the command that failed */
-		ret = ucsi_acknowledge(ucsi, false);
-		if (ret)
-			return ret;
-
-		if (cmd == UCSI_GET_ERROR_STATUS)
-			return -EIO;
-
-		return ucsi_read_error(ucsi);
-	}
-
-	if (cmd == UCSI_CANCEL && cci & UCSI_CCI_CANCEL_COMPLETE) {
-		ret = ucsi_acknowledge(ucsi, false);
-		return ret ? ret : -EBUSY;
-	}
-
-	return UCSI_CCI_LENGTH(cci);
-}
-
 static int ucsi_send_command_common(struct ucsi *ucsi, u64 command,
 				    void *data, size_t size, bool conn_ack)
 {
-	u8 length;
+	u32 cci;
 	int ret;
 
 	mutex_lock(&ucsi->ppm_lock);
 
-	ret = ucsi_exec_command(ucsi, command);
-	if (ret < 0)
-		goto out;
-
-	length = ret;
-
-	if (data) {
-		ret = ucsi_read_message_in(ucsi, data, size);
-		if (ret)
-			goto out;
+	ret = ucsi_run_command(ucsi, command, &cci, data, size, conn_ack);
+	if (cci & UCSI_CCI_BUSY) {
+		ret = ucsi_run_command(ucsi, UCSI_CANCEL, &cci, NULL, 0, false);
+		return ret ? ret : -EBUSY;
 	}
 
-	ret = ucsi_acknowledge(ucsi, conn_ack);
-	if (ret)
-		goto out;
+	if (cci & UCSI_CCI_ERROR)
+		return ucsi_read_error(ucsi);
 
-	ret = length;
-out:
 	mutex_unlock(&ucsi->ppm_lock);
 	return ret;
 }

-- 
2.39.2