[PATCH next v3] i2c: hisi: Add support to get clock frequency from clock property

[Weilong Chen]

Support the driver to obtain clock information by clk_rate or
clock property. Find clock first, if not, fall back to clk_rate.

Signed-off-by: Weilong Chen <chenweilong@xxxxxxxxxx>
Acked-by: Yicong Yang <yangyicong@xxxxxxxxxxxxx>
---
Change since v1:
- Ordered struct field to inverted triangle.
- Use devm_clk_get_optional_enabled().
- Use IS_ERR_OR_NULL.
Link: https://lore.kernel.org/lkml/20220921101540.352553-1-chenweilong@xxxxxxxxxx/

Change since v2:
- Remove redundant blank line
Link: https://lore.kernel.org/all/20220923011417.78994-1-chenweilong@xxxxxxxxxx/

 drivers/i2c/busses/i2c-hisi.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-hisi.c b/drivers/i2c/busses/i2c-hisi.c
index 67031024217c..e4b0ebe54f6f 100644
--- a/drivers/i2c/busses/i2c-hisi.c
+++ b/drivers/i2c/busses/i2c-hisi.c
@@ -8,6 +8,7 @@
 #include <linux/acpi.h>
 #include <linux/bits.h>
 #include <linux/bitfield.h>
+#include <linux/clk.h>
 #include <linux/completion.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
@@ -90,6 +91,7 @@ struct hisi_i2c_controller {
 	struct i2c_adapter adapter;
 	void __iomem *iobase;
 	struct device *dev;
+	struct clk *clk;
 	int irq;
 
 	/* Intermediates for recording the transfer process */
@@ -456,10 +458,15 @@ static int hisi_i2c_probe(struct platform_device *pdev)
 		return ret;
 	}
 
-	ret = device_property_read_u64(dev, "clk_rate", &clk_rate_hz);
-	if (ret) {
-		dev_err(dev, "failed to get clock frequency, ret = %d\n", ret);
-		return ret;
+	ctlr->clk = devm_clk_get_optional_enabled(&pdev->dev, NULL);
+	if (IS_ERR_OR_NULL(ctlr->clk)) {
+		ret = device_property_read_u64(dev, "clk_rate", &clk_rate_hz);
+		if (ret) {
+			dev_err(dev, "failed to get clock frequency, ret = %d\n", ret);
+			return ret;
+		}
+	} else {
+		clk_rate_hz = clk_get_rate(ctlr->clk);
 	}
 
 	ctlr->clk_rate_khz = DIV_ROUND_UP_ULL(clk_rate_hz, HZ_PER_KHZ);
-- 
2.31.GIT