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From:   Michal Simek <michal.simek@amd.com>
To:     <linux-kernel@vger.kernel.org>, <monstr@monstr.eu>,
        <michal.simek@xilinx.com>, <git@xilinx.com>
CC:     Srinivas Neeli <srinivas.neeli@amd.com>,
        Appana Durga Kedareswara rao <appana.durga.rao@xilinx.com>,
        "David S. Miller" <davem@davemloft.net>,
        "Eric Dumazet" <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        "Marc Kleine-Budde" <mkl@pengutronix.de>,
        Naga Sureshkumar Relli <naga.sureshkumar.relli@xilinx.com>,
        Paolo Abeni <pabeni@redhat.com>,
        "Philipp Zabel" <p.zabel@pengutronix.de>,
        Wolfgang Grandegger <wg@grandegger.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-can@vger.kernel.org>, <netdev@vger.kernel.org>
Subject: [PATCH 2/2] can: xilinx_can: Add support for controller reset
Date:   Tue, 11 Jul 2023 16:03:55 +0200
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From: Srinivas Neeli <srinivas.neeli@amd.com>

Add support for an optional reset for the CAN controller using the reset
driver. If the CAN node contains the "resets" property, then this logic
will perform CAN controller reset.

Signed-off-by: Srinivas Neeli <srinivas.neeli@amd.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
---

 drivers/net/can/xilinx_can.c | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/xilinx_can.c b/drivers/net/can/xilinx_can.c
index 4d3283db3a13..929e00061898 100644
--- a/drivers/net/can/xilinx_can.c
+++ b/drivers/net/can/xilinx_can.c
@@ -30,6 +30,7 @@
 #include <linux/can/error.h>
 #include <linux/phy/phy.h>
 #include <linux/pm_runtime.h>
+#include <linux/reset.h>
 
 #define DRIVER_NAME	"xilinx_can"
 
@@ -200,6 +201,7 @@ struct xcan_devtype_data {
  * @can_clk:			Pointer to struct clk
  * @devtype:			Device type specific constants
  * @transceiver:		Optional pointer to associated CAN transceiver
+ * @rstc:			Pointer to reset control
  */
 struct xcan_priv {
 	struct can_priv can;
@@ -218,6 +220,7 @@ struct xcan_priv {
 	struct clk *can_clk;
 	struct xcan_devtype_data devtype;
 	struct phy *transceiver;
+	struct reset_control *rstc;
 };
 
 /* CAN Bittiming constants as per Xilinx CAN specs */
@@ -1799,6 +1802,16 @@ static int xcan_probe(struct platform_device *pdev)
 	priv->can.do_get_berr_counter = xcan_get_berr_counter;
 	priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
 					CAN_CTRLMODE_BERR_REPORTING;
+	priv->rstc = devm_reset_control_get_optional_exclusive(&pdev->dev, NULL);
+	if (IS_ERR(priv->rstc)) {
+		dev_err(&pdev->dev, "Cannot get CAN reset.\n");
+		ret = PTR_ERR(priv->rstc);
+		goto err_free;
+	}
+
+	ret = reset_control_reset(priv->rstc);
+	if (ret)
+		goto err_free;
 
 	if (devtype->cantype == XAXI_CANFD) {
 		priv->can.data_bittiming_const =
@@ -1827,7 +1840,7 @@ static int xcan_probe(struct platform_device *pdev)
 	/* Get IRQ for the device */
 	ret = platform_get_irq(pdev, 0);
 	if (ret < 0)
-		goto err_free;
+		goto err_reset;
 
 	ndev->irq = ret;
 
@@ -1843,21 +1856,21 @@ static int xcan_probe(struct platform_device *pdev)
 	if (IS_ERR(priv->can_clk)) {
 		ret = dev_err_probe(&pdev->dev, PTR_ERR(priv->can_clk),
 				    "device clock not found\n");
-		goto err_free;
+		goto err_reset;
 	}
 
 	priv->bus_clk = devm_clk_get(&pdev->dev, devtype->bus_clk_name);
 	if (IS_ERR(priv->bus_clk)) {
 		ret = dev_err_probe(&pdev->dev, PTR_ERR(priv->bus_clk),
 				    "bus clock not found\n");
-		goto err_free;
+		goto err_reset;
 	}
 
 	transceiver = devm_phy_optional_get(&pdev->dev, NULL);
 	if (IS_ERR(transceiver)) {
 		ret = PTR_ERR(transceiver);
 		dev_err_probe(&pdev->dev, ret, "failed to get phy\n");
-		goto err_free;
+		goto err_reset;
 	}
 	priv->transceiver = transceiver;
 
@@ -1904,6 +1917,8 @@ static int xcan_probe(struct platform_device *pdev)
 err_disableclks:
 	pm_runtime_put(priv->dev);
 	pm_runtime_disable(&pdev->dev);
+err_reset:
+	reset_control_assert(priv->rstc);
 err_free:
 	free_candev(ndev);
 err:
@@ -1920,10 +1935,12 @@ static int xcan_probe(struct platform_device *pdev)
 static void xcan_remove(struct platform_device *pdev)
 {
 	struct net_device *ndev = platform_get_drvdata(pdev);
+	struct xcan_priv *priv = netdev_priv(ndev);
 
 	unregister_candev(ndev);
 	pm_runtime_disable(&pdev->dev);
 	free_candev(ndev);
+	reset_control_assert(priv->rstc);
 }
 
 static struct platform_driver xcan_driver = {
-- 
2.36.1