linux-kernel - [PATCH 2/2] can: flexcan: add support for PE clock source select

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Date:   Thu, 13 Dec 2018 07:08:00 +0000
From:   Joakim Zhang <qiangqing.zhang@....com>
To:     "mkl@...gutronix.de" <mkl@...gutronix.de>,
        "robh@...nel.org" <robh@...nel.org>
CC:     "linux-can@...r.kernel.org" <linux-can@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>,
        Aisheng Dong <aisheng.dong@....com>,
        Joakim Zhang <qiangqing.zhang@....com>
Subject: [PATCH 2/2] can: flexcan: add support for PE clock source select

From: Dong Aisheng <aisheng.dong@....com>

Add support to select the clock source for CAN Protocol Engine (PE).
It's Soc Implementation dependent. Refer to RM for detailed definition
of each Soc. We select clock source 1 (peripheral clock) by default in
driver now, this patch add support to prase clock source in DTS file.

Signed-off-by: Dong Aisheng <aisheng.dong@....com>
Signed-off-by: Joakim Zhang <qiangqing.zhang@....com>
---
 drivers/net/can/flexcan.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index 0f36eafe3ac1..2bca867bcfaa 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -273,6 +273,8 @@ struct flexcan_priv {
 	u8 tx_mb_idx;
 	u8 mb_count;
 	u8 mb_size;
+	/* Select clock source to CAN Protocol Engine */
+	u8 clk_src;
 	u32 reg_ctrl_default;
 	u32 reg_imask1_default;
 	u32 reg_imask2_default;
@@ -1361,9 +1363,12 @@ static int register_flexcandev(struct net_device *dev)
 	err = flexcan_chip_disable(priv);
 	if (err)
 		goto out_disable_per;
-	reg = priv->read(&regs->ctrl);
-	reg |= FLEXCAN_CTRL_CLK_SRC;
-	priv->write(reg, &regs->ctrl);
+
+	if (priv->clk_src) {
+		reg = priv->read(&regs->ctrl);
+		reg |= FLEXCAN_CTRL_CLK_SRC;
+		priv->write(reg, &regs->ctrl);
+	}
 
 	err = flexcan_chip_enable(priv);
 	if (err)
@@ -1488,6 +1493,7 @@ static int flexcan_probe(struct platform_device *pdev)
 	struct clk *clk_ipg = NULL, *clk_per = NULL;
 	struct flexcan_regs __iomem *regs;
 	int err, irq;
+	u8 clk_src = 1;
 	u32 clock_freq = 0;
 
 	reg_xceiver = devm_regulator_get(&pdev->dev, "xceiver");
@@ -1496,9 +1502,12 @@ static int flexcan_probe(struct platform_device *pdev)
 	else if (IS_ERR(reg_xceiver))
 		reg_xceiver = NULL;
 
-	if (pdev->dev.of_node)
+	if (pdev->dev.of_node) {
 		of_property_read_u32(pdev->dev.of_node,
 				     "clock-frequency", &clock_freq);
+		of_property_read_u8(pdev->dev.of_node,
+				    "fsl,clk-source", &clk_src);
+	}
 
 	if (!clock_freq) {
 		clk_ipg = devm_clk_get(&pdev->dev, "ipg");
@@ -1556,6 +1565,7 @@ static int flexcan_probe(struct platform_device *pdev)
 		priv->write = flexcan_write_le;
 	}
 
+	priv->clk_src = clk_src;
 	priv->can.clock.freq = clock_freq;
 	priv->can.bittiming_const = &flexcan_bittiming_const;
 	priv->can.do_set_mode = flexcan_set_mode;
-- 
2.17.1