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Date: Mon, 27 Nov 2023 15:58:14 +0530
From: Srinivas Goud <srinivas.goud@....com>
To: <wg@...ndegger.com>, <mkl@...gutronix.de>, <davem@...emloft.net>,
	<edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>,
	<robh+dt@...nel.org>, <krzysztof.kozlowski+dt@...aro.org>,
	<conor+dt@...nel.org>, <p.zabel@...gutronix.de>
CC: <git@....com>, <michal.simek@...inx.com>, <linux-can@...r.kernel.org>,
	<netdev@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
	<appana.durga.rao@...inx.com>, Srinivas Goud <srinivas.goud@....com>
Subject: [PATCH v7 2/3] can: xilinx_can: Add ECC support

Add ECC support for Xilinx CAN Controller, so this driver reports
1bit/2bit ECC errors for FIFO's based on ECC error interrupt.
ECC feature for Xilinx CAN Controller selected through 'xlnx,has-ecc'
DT property

Signed-off-by: Srinivas Goud <srinivas.goud@....com>
---
Changes in v7:
None

Changes in v6:
None

Changes in v5:
Address review comments
Change the sequence of updates the stats
Use u64 stats helper function

Changes in v4:
None

Changes in v3:
None

Changes in v2:
Address review comments

 drivers/net/can/xilinx_can.c | 105 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 101 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/xilinx_can.c b/drivers/net/can/xilinx_can.c
index abe58f1..c8691a1 100644
--- a/drivers/net/can/xilinx_can.c
+++ b/drivers/net/can/xilinx_can.c
@@ -31,6 +31,7 @@
 #include <linux/phy/phy.h>
 #include <linux/pm_runtime.h>
 #include <linux/reset.h>
+#include <linux/u64_stats_sync.h>
 
 #define DRIVER_NAME	"xilinx_can"
 
@@ -58,6 +59,13 @@ enum xcan_reg {
 					  */
 	XCAN_F_BTR_OFFSET	= 0x08C, /* Data Phase Bit Timing */
 	XCAN_TRR_OFFSET		= 0x0090, /* TX Buffer Ready Request */
+
+	/* only on AXI CAN cores */
+	XCAN_ECC_CFG_OFFSET	= 0xC8, /* ECC Configuration */
+	XCAN_TXTLFIFO_ECC_OFFSET	= 0xCC, /* TXTL FIFO ECC error counter */
+	XCAN_TXOLFIFO_ECC_OFFSET	= 0xD0, /* TXOL FIFO ECC error counter */
+	XCAN_RXFIFO_ECC_OFFSET	= 0xD4, /* RX FIFO ECC error counter */
+
 	XCAN_AFR_EXT_OFFSET	= 0x00E0, /* Acceptance Filter */
 	XCAN_FSR_OFFSET		= 0x00E8, /* RX FIFO Status */
 	XCAN_TXMSG_BASE_OFFSET	= 0x0100, /* TX Message Space */
@@ -124,6 +132,18 @@ enum xcan_reg {
 #define XCAN_IXR_TXFLL_MASK		0x00000004 /* Tx FIFO Full intr */
 #define XCAN_IXR_TXOK_MASK		0x00000002 /* TX successful intr */
 #define XCAN_IXR_ARBLST_MASK		0x00000001 /* Arbitration lost intr */
+#define XCAN_IXR_E2BERX_MASK		BIT(23) /* RX FIFO two bit ECC error */
+#define XCAN_IXR_E1BERX_MASK		BIT(22) /* RX FIFO one bit ECC error */
+#define XCAN_IXR_E2BETXOL_MASK		BIT(21) /* TXOL FIFO two bit ECC error */
+#define XCAN_IXR_E1BETXOL_MASK		BIT(20) /* TXOL FIFO One bit ECC error */
+#define XCAN_IXR_E2BETXTL_MASK		BIT(19) /* TXTL FIFO Two bit ECC error */
+#define XCAN_IXR_E1BETXTL_MASK		BIT(18) /* TXTL FIFO One bit ECC error */
+#define XCAN_IXR_ECC_MASK		(XCAN_IXR_E2BERX_MASK | \
+					XCAN_IXR_E1BERX_MASK | \
+					XCAN_IXR_E2BETXOL_MASK | \
+					XCAN_IXR_E1BETXOL_MASK | \
+					XCAN_IXR_E2BETXTL_MASK | \
+					XCAN_IXR_E1BETXTL_MASK)
 #define XCAN_IDR_ID1_MASK		0xFFE00000 /* Standard msg identifier */
 #define XCAN_IDR_SRR_MASK		0x00100000 /* Substitute remote TXreq */
 #define XCAN_IDR_IDE_MASK		0x00080000 /* Identifier extension */
@@ -137,6 +157,11 @@ enum xcan_reg {
 #define XCAN_2_FSR_RI_MASK		0x0000003F /* RX Read Index */
 #define XCAN_DLCR_EDL_MASK		0x08000000 /* EDL Mask in DLC */
 #define XCAN_DLCR_BRS_MASK		0x04000000 /* BRS Mask in DLC */
+#define XCAN_ECC_CFG_REECRX_MASK	BIT(2) /* Reset RX FIFO ECC error counters */
+#define XCAN_ECC_CFG_REECTXOL_MASK	BIT(1) /* Reset TXOL FIFO ECC error counters */
+#define XCAN_ECC_CFG_REECTXTL_MASK	BIT(0) /* Reset TXTL FIFO ECC error counters */
+#define XCAN_ECC_1BIT_CNT_MASK		GENMASK(15, 0) /* FIFO ECC 1bit count mask */
+#define XCAN_ECC_2BIT_CNT_MASK		GENMASK(31, 16) /* FIFO ECC 2bit count mask */
 
 /* CAN register bit shift - XCAN_<REG>_<BIT>_SHIFT */
 #define XCAN_BRPR_TDC_ENABLE		BIT(16) /* Transmitter Delay Compensation (TDC) Enable */
@@ -202,6 +227,13 @@ struct xcan_devtype_data {
  * @devtype:			Device type specific constants
  * @transceiver:		Optional pointer to associated CAN transceiver
  * @rstc:			Pointer to reset control
+ * @ecc_enable:			ECC enable flag
+ * @ecc_2bit_rxfifo_cnt:	RXFIFO 2bit ECC count
+ * @ecc_1bit_rxfifo_cnt:	RXFIFO 1bit ECC count
+ * @ecc_2bit_txolfifo_cnt:	TXOLFIFO 2bit ECC count
+ * @ecc_1bit_txolfifo_cnt:	TXOLFIFO 1bit ECC count
+ * @ecc_2bit_txtlfifo_cnt:	TXTLFIFO 2bit ECC count
+ * @ecc_1bit_txtlfifo_cnt:	TXTLFIFO 1bit ECC count
  */
 struct xcan_priv {
 	struct can_priv can;
@@ -221,6 +253,13 @@ struct xcan_priv {
 	struct xcan_devtype_data devtype;
 	struct phy *transceiver;
 	struct reset_control *rstc;
+	bool ecc_enable;
+	u64_stats_t ecc_2bit_rxfifo_cnt;
+	u64_stats_t ecc_1bit_rxfifo_cnt;
+	u64_stats_t ecc_2bit_txolfifo_cnt;
+	u64_stats_t ecc_1bit_txolfifo_cnt;
+	u64_stats_t ecc_2bit_txtlfifo_cnt;
+	u64_stats_t ecc_1bit_txtlfifo_cnt;
 };
 
 /* CAN Bittiming constants as per Xilinx CAN specs */
@@ -523,6 +562,9 @@ static int xcan_chip_start(struct net_device *ndev)
 		XCAN_IXR_ERROR_MASK | XCAN_IXR_RXOFLW_MASK |
 		XCAN_IXR_ARBLST_MASK | xcan_rx_int_mask(priv);
 
+	if (priv->ecc_enable)
+		ier |= XCAN_IXR_ECC_MASK;
+
 	if (priv->devtype.flags & XCAN_FLAG_RXMNF)
 		ier |= XCAN_IXR_RXMNF_MASK;
 
@@ -1127,6 +1169,50 @@ static void xcan_err_interrupt(struct net_device *ndev, u32 isr)
 		priv->can.can_stats.bus_error++;
 	}
 
+	if (priv->ecc_enable && isr & XCAN_IXR_ECC_MASK) {
+		u32 reg_rx_ecc, reg_txol_ecc, reg_txtl_ecc;
+
+		reg_rx_ecc = priv->read_reg(priv, XCAN_RXFIFO_ECC_OFFSET);
+		reg_txol_ecc = priv->read_reg(priv, XCAN_TXOLFIFO_ECC_OFFSET);
+		reg_txtl_ecc = priv->read_reg(priv, XCAN_TXTLFIFO_ECC_OFFSET);
+
+		/* The counter reaches its maximum at 0xffff and does not overflow.
+		 * Accept the small race window between reading and resetting ECC counters.
+		 */
+		priv->write_reg(priv, XCAN_ECC_CFG_OFFSET, XCAN_ECC_CFG_REECRX_MASK |
+				XCAN_ECC_CFG_REECTXOL_MASK | XCAN_ECC_CFG_REECTXTL_MASK);
+
+		if (isr & XCAN_IXR_E2BERX_MASK) {
+			u64_stats_add(&priv->ecc_2bit_rxfifo_cnt,
+				      FIELD_GET(XCAN_ECC_2BIT_CNT_MASK, reg_rx_ecc));
+		}
+
+		if (isr & XCAN_IXR_E1BERX_MASK) {
+			u64_stats_add(&priv->ecc_1bit_rxfifo_cnt,
+				      FIELD_GET(XCAN_ECC_1BIT_CNT_MASK, reg_rx_ecc));
+		}
+
+		if (isr & XCAN_IXR_E2BETXOL_MASK) {
+			u64_stats_add(&priv->ecc_2bit_txolfifo_cnt,
+				      FIELD_GET(XCAN_ECC_2BIT_CNT_MASK, reg_txol_ecc));
+		}
+
+		if (isr & XCAN_IXR_E1BETXOL_MASK) {
+			u64_stats_add(&priv->ecc_1bit_txolfifo_cnt,
+				      FIELD_GET(XCAN_ECC_1BIT_CNT_MASK, reg_txol_ecc));
+		}
+
+		if (isr & XCAN_IXR_E2BETXTL_MASK) {
+			u64_stats_add(&priv->ecc_2bit_txtlfifo_cnt,
+				      FIELD_GET(XCAN_ECC_2BIT_CNT_MASK, reg_txtl_ecc));
+		}
+
+		if (isr & XCAN_IXR_E1BETXTL_MASK) {
+			u64_stats_add(&priv->ecc_1bit_txtlfifo_cnt,
+				      FIELD_GET(XCAN_ECC_1BIT_CNT_MASK, reg_txtl_ecc));
+		}
+	}
+
 	if (cf.can_id) {
 		struct can_frame *skb_cf;
 		struct sk_buff *skb = alloc_can_err_skb(ndev, &skb_cf);
@@ -1355,7 +1441,7 @@ static irqreturn_t xcan_interrupt(int irq, void *dev_id)
 	struct net_device *ndev = (struct net_device *)dev_id;
 	struct xcan_priv *priv = netdev_priv(ndev);
 	u32 isr, ier;
-	u32 isr_errors;
+	u32 isr_errors, mask;
 	u32 rx_int_mask = xcan_rx_int_mask(priv);
 
 	/* Get the interrupt status from Xilinx CAN */
@@ -1374,10 +1460,15 @@ static irqreturn_t xcan_interrupt(int irq, void *dev_id)
 	if (isr & XCAN_IXR_TXOK_MASK)
 		xcan_tx_interrupt(ndev, isr);
 
+	mask = XCAN_IXR_ERROR_MASK | XCAN_IXR_RXOFLW_MASK |
+		XCAN_IXR_BSOFF_MASK | XCAN_IXR_ARBLST_MASK |
+		XCAN_IXR_RXMNF_MASK;
+
+	if (priv->ecc_enable)
+		mask |= XCAN_IXR_ECC_MASK;
+
 	/* Check for the type of error interrupt and Processing it */
-	isr_errors = isr & (XCAN_IXR_ERROR_MASK | XCAN_IXR_RXOFLW_MASK |
-			    XCAN_IXR_BSOFF_MASK | XCAN_IXR_ARBLST_MASK |
-			    XCAN_IXR_RXMNF_MASK);
+	isr_errors = isr & mask;
 	if (isr_errors) {
 		priv->write_reg(priv, XCAN_ICR_OFFSET, isr_errors);
 		xcan_err_interrupt(ndev, isr);
@@ -1796,6 +1887,7 @@ static int xcan_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	priv = netdev_priv(ndev);
+	priv->ecc_enable = of_property_read_bool(pdev->dev.of_node, "xlnx,has-ecc");
 	priv->dev = &pdev->dev;
 	priv->can.bittiming_const = devtype->bittiming_const;
 	priv->can.do_set_mode = xcan_do_set_mode;
@@ -1912,6 +2004,11 @@ static int xcan_probe(struct platform_device *pdev)
 		   priv->reg_base, ndev->irq, priv->can.clock.freq,
 		   hw_tx_max, priv->tx_max);
 
+	if (priv->ecc_enable) {
+		/* Reset FIFO ECC counters */
+		priv->write_reg(priv, XCAN_ECC_CFG_OFFSET, XCAN_ECC_CFG_REECRX_MASK |
+			XCAN_ECC_CFG_REECTXOL_MASK | XCAN_ECC_CFG_REECTXTL_MASK);
+	}
 	return 0;
 
 err_disableclks:
-- 
2.1.1


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