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From:   Haotien Hsu <haotienh@nvidia.com>
To:     Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC:     Sing-Han Chen <singhanc@nvidia.com>,
        Sanket Goswami <Sanket.Goswami@amd.com>,
        Wayne Chang <waynec@nvidia.com>,
        =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= 
        <u.kleine-koenig@pengutronix.de>,
        Jonathan Hunter <jonathanh@nvidia.com>,
        <linux-usb@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        Haotien Hsu <haotienh@nvidia.com>
Subject: [PATCH v4] ucsi_ccg: Refine the UCSI Interrupt handling
Date:   Wed, 18 Jan 2023 14:15:23 +0800
Message-ID: <20230118061523.1537992-1-haotienh@nvidia.com>
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From: Sing-Han Chen <singhanc@nvidia.com>

For the CCGx, when the OPM field in the INTR_REG is cleared, then the
CCI data in the PPM is reset.

To align with the CCGx UCSI interface guide, this patch updates the
driver to copy CCI and MESSAGE_IN before clearing UCSI interrupt.
When a new command is sent, the driver will clear the old CCI and
MESSAGE_IN copy.

Finally, clear UCSI_READ_INT before calling complete() to ensure that
the ucsi_ccg_sync_write() would wait for the interrupt handling to
complete.
It prevents the driver from resetting CCI prematurely.

Signed-off-by: Sing-Han Chen <singhanc@nvidia.com>
Signed-off-by: Haotien Hsu <haotienh@nvidia.com>
---
V1->V2
- Fix uninitialized symbol 'cci'
v2->v3
- Remove misusing Reported-by tags
v3->v4
- Add comments for op_lock
---
 drivers/usb/typec/ucsi/ucsi_ccg.c | 90 ++++++++++++++++++++++++++++---
 1 file changed, 83 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/typec/ucsi/ucsi_ccg.c b/drivers/usb/typec/ucsi/ucsi_ccg.c
index eab3012e1b01..532813a32cc1 100644
--- a/drivers/usb/typec/ucsi/ucsi_ccg.c
+++ b/drivers/usb/typec/ucsi/ucsi_ccg.c
@@ -192,6 +192,12 @@ struct ucsi_ccg_altmode {
 	bool checked;
 } __packed;
 
+#define CCGX_MESSAGE_IN_MAX 4
+struct op_region {
+	u32 cci;
+	u32 message_in[CCGX_MESSAGE_IN_MAX];
+};
+
 struct ucsi_ccg {
 	struct device *dev;
 	struct ucsi *ucsi;
@@ -222,6 +228,13 @@ struct ucsi_ccg {
 	bool has_multiple_dp;
 	struct ucsi_ccg_altmode orig[UCSI_MAX_ALTMODES];
 	struct ucsi_ccg_altmode updated[UCSI_MAX_ALTMODES];
+
+	/*
+	 * This spinlock protects op_data which includes CCI and MESSAGE_IN that
+	 * will be updated in ISR
+	 */
+	spinlock_t op_lock;
+	struct op_region op_data;
 };
 
 static int ccg_read(struct ucsi_ccg *uc, u16 rab, u8 *data, u32 len)
@@ -305,12 +318,57 @@ static int ccg_write(struct ucsi_ccg *uc, u16 rab, const u8 *data, u32 len)
 	return 0;
 }
 
+static void ccg_op_region_read(struct ucsi_ccg *uc, unsigned int offset,
+		void *val, size_t val_len)
+{
+	struct op_region *data = &uc->op_data;
+
+	spin_lock(&uc->op_lock);
+	if (offset == UCSI_CCI)
+		memcpy(val, &data->cci, val_len);
+	else if (offset == UCSI_MESSAGE_IN)
+		memcpy(val, &data->message_in, val_len);
+	spin_unlock(&uc->op_lock);
+}
+
+static void ccg_op_region_update(struct ucsi_ccg *uc, u32 cci)
+{
+	u16 reg = CCGX_RAB_UCSI_DATA_BLOCK(UCSI_MESSAGE_IN);
+	struct op_region *data = &uc->op_data;
+	u32 message_in[CCGX_MESSAGE_IN_MAX];
+
+	if (UCSI_CCI_LENGTH(cci))
+		if (ccg_read(uc, reg, (void *)&message_in,
+					sizeof(message_in))) {
+			dev_err(uc->dev, "failed to read MESSAGE_IN\n");
+			return;
+		}
+
+	spin_lock(&uc->op_lock);
+	memcpy(&data->cci, &cci, sizeof(cci));
+	if (UCSI_CCI_LENGTH(cci))
+		memcpy(&data->message_in, &message_in, sizeof(message_in));
+	spin_unlock(&uc->op_lock);
+}
+
+static void ccg_op_region_clean(struct ucsi_ccg *uc)
+{
+	struct op_region *data = &uc->op_data;
+
+	spin_lock(&uc->op_lock);
+	memset(&data->cci, 0, sizeof(data->cci));
+	memset(&data->message_in, 0, sizeof(data->message_in));
+	spin_unlock(&uc->op_lock);
+}
+
 static int ucsi_ccg_init(struct ucsi_ccg *uc)
 {
 	unsigned int count = 10;
 	u8 data;
 	int status;
 
+	spin_lock_init(&uc->op_lock);
+
 	data = CCGX_RAB_UCSI_CONTROL_STOP;
 	status = ccg_write(uc, CCGX_RAB_UCSI_CONTROL, &data, sizeof(data));
 	if (status < 0)
@@ -520,9 +578,13 @@ static int ucsi_ccg_read(struct ucsi *ucsi, unsigned int offset,
 	u16 reg = CCGX_RAB_UCSI_DATA_BLOCK(offset);
 	struct ucsi_capability *cap;
 	struct ucsi_altmode *alt;
-	int ret;
+	int ret = 0;
+
+	if ((offset == UCSI_CCI) || (offset == UCSI_MESSAGE_IN))
+		ccg_op_region_read(uc, offset, val, val_len);
+	else
+		ret = ccg_read(uc, reg, val, val_len);
 
-	ret = ccg_read(uc, reg, val, val_len);
 	if (ret)
 		return ret;
 
@@ -559,9 +621,13 @@ static int ucsi_ccg_read(struct ucsi *ucsi, unsigned int offset,
 static int ucsi_ccg_async_write(struct ucsi *ucsi, unsigned int offset,
 				const void *val, size_t val_len)
 {
+	struct ucsi_ccg *uc = ucsi_get_drvdata(ucsi);
 	u16 reg = CCGX_RAB_UCSI_DATA_BLOCK(offset);
 
-	return ccg_write(ucsi_get_drvdata(ucsi), reg, val, val_len);
+	if (offset == UCSI_CONTROL)
+		ccg_op_region_clean(uc);
+
+	return ccg_write(uc, reg, val, val_len);
 }
 
 static int ucsi_ccg_sync_write(struct ucsi *ucsi, unsigned int offset,
@@ -616,12 +682,17 @@ static irqreturn_t ccg_irq_handler(int irq, void *data)
 	struct ucsi_ccg *uc = data;
 	u8 intr_reg;
 	u32 cci;
-	int ret;
+	int ret = 0;
 
 	ret = ccg_read(uc, CCGX_RAB_INTR_REG, &intr_reg, sizeof(intr_reg));
 	if (ret)
 		return ret;
 
+	if (!intr_reg)
+		return IRQ_HANDLED;
+	else if (!(intr_reg & UCSI_READ_INT))
+		goto err_clear_irq;
+
 	ret = ccg_read(uc, reg, (void *)&cci, sizeof(cci));
 	if (ret)
 		goto err_clear_irq;
@@ -629,13 +700,18 @@ static irqreturn_t ccg_irq_handler(int irq, void *data)
 	if (UCSI_CCI_CONNECTOR(cci))
 		ucsi_connector_change(uc->ucsi, UCSI_CCI_CONNECTOR(cci));
 
-	if (test_bit(DEV_CMD_PENDING, &uc->flags) &&
-	    cci & (UCSI_CCI_ACK_COMPLETE | UCSI_CCI_COMMAND_COMPLETE))
-		complete(&uc->complete);
+	/* As per CCGx UCSI interface guide, copy CCI and MESSAGE_IN
+	 * to the OpRegion before clear the UCSI interrupt
+	 */
+	ccg_op_region_update(uc, cci);
 
 err_clear_irq:
 	ccg_write(uc, CCGX_RAB_INTR_REG, &intr_reg, sizeof(intr_reg));
 
+	if (!ret && test_bit(DEV_CMD_PENDING, &uc->flags) &&
+	    cci & (UCSI_CCI_ACK_COMPLETE | UCSI_CCI_COMMAND_COMPLETE))
+		complete(&uc->complete);
+
 	return IRQ_HANDLED;
 }
 
-- 
2.25.1