[PATCH v2 2/2] can: flexcan: make PE clock info conditional

[Pankaj Bansal <pankaj.bansal@xxxxxxx>]

PE clock info can be skipped if the synchronous clocking is to be used
in flexcan.

Refer Documentation/devicetree/bindings/net/can/fsl-flexcan.txt for more
info.

Signed-off-by: Pankaj Bansal <pankaj.bansal@xxxxxxx>
---

Notes:
    Dependencies:
    [1] https://lore.kernel.org/patchwork/cover/1024536/
    [2] https://lore.kernel.org/patchwork/patch/1001918/
    
    V2:
    - modified the clk_src == 0 to !clk_src
    - modified changes in flexcan_clks_enable
    - Added Dependencies in Notes

 drivers/net/can/flexcan.c | 39 +++++++++++++++++++++++++------------
 1 file changed, 27 insertions(+), 12 deletions(-)

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index 5f4075d598d0..249fc0a6f85d 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -515,21 +515,24 @@ static int flexcan_clks_enable(const struct flexcan_priv *priv)
 {
 	int err;
 
-	err = clk_prepare_enable(priv->clk_ipg);
+	err = clk_prepare_enable(priv->clk_per);
 	if (err)
 		return err;
 
-	err = clk_prepare_enable(priv->clk_per);
-	if (err)
-		clk_disable_unprepare(priv->clk_ipg);
+	if (priv->clk_ipg) {
+		err = clk_prepare_enable(priv->clk_ipg);
+		if (err)
+			clk_disable_unprepare(priv->clk_per);
+	}
 
 	return err;
 }
 
 static void flexcan_clks_disable(const struct flexcan_priv *priv)
 {
+	if (priv->clk_ipg)
+		clk_disable_unprepare(priv->clk_ipg);
 	clk_disable_unprepare(priv->clk_per);
-	clk_disable_unprepare(priv->clk_ipg);
 }
 
 static inline int flexcan_transceiver_enable(const struct flexcan_priv *priv)
@@ -1688,18 +1691,30 @@ static int flexcan_probe(struct platform_device *pdev)
 	}
 
 	if (!clock_freq) {
-		clk_ipg = devm_clk_get(&pdev->dev, "ipg");
-		if (IS_ERR(clk_ipg)) {
-			dev_err(&pdev->dev, "no ipg clock defined\n");
-			return PTR_ERR(clk_ipg);
-		}
-
 		clk_per = devm_clk_get(&pdev->dev, "per");
 		if (IS_ERR(clk_per)) {
 			dev_err(&pdev->dev, "no per clock defined\n");
 			return PTR_ERR(clk_per);
 		}
-		clock_freq = clk_get_rate(clk_per);
+
+		if (!clk_src) {
+			// only get oscillator clock if asynchronous clocking
+			// is to be used.
+			clk_ipg = devm_clk_get(&pdev->dev, "ipg");
+			if (IS_ERR(clk_ipg)) {
+				dev_err(&pdev->dev, "no ipg clock defined\n");
+				return PTR_ERR(clk_ipg);
+			}
+
+			clock_freq = clk_get_rate(clk_ipg);
+			if (clock_freq >= clk_get_rate(clk_per)) {
+				dev_err(&pdev->dev,
+					"PE clock should be less than CHI\n");
+				return -EINVAL;
+			}
+		} else {
+			clock_freq = clk_get_rate(clk_per);
+		}
 	}
 
 	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-- 
2.17.1