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

[Weilong Chen <chenweilong@huawei.com>]

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@huawei.com>
---
 drivers/i2c/busses/i2c-hisi.c | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/i2c/busses/i2c-hisi.c b/drivers/i2c/busses/i2c-hisi.c
index 67031024217c..5e48d4ee0c6d 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>
@@ -91,6 +92,7 @@ struct hisi_i2c_controller {
 	void __iomem *iobase;
 	struct device *dev;
 	int irq;
+	struct clk *clk;
 
 	/* Intermediates for recording the transfer process */
 	struct completion *completion;
@@ -456,10 +458,21 @@ 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(&pdev->dev, NULL);
+	if (IS_ERR(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 {
+		ret = clk_prepare_enable(ctlr->clk);
+		if (ret) {
+			dev_err(dev, "failed to enable clock, ret = %d\n", ret);
+			return ret;
+		}
+
+		clk_rate_hz = clk_get_rate(ctlr->clk);
 	}
 
 	ctlr->clk_rate_khz = DIV_ROUND_UP_ULL(clk_rate_hz, HZ_PER_KHZ);
@@ -475,8 +488,10 @@ static int hisi_i2c_probe(struct platform_device *pdev)
 	i2c_set_adapdata(adapter, ctlr);
 
 	ret = devm_i2c_add_adapter(dev, adapter);
-	if (ret)
+	if (ret) {
+		clk_disable_unprepare(ctlr->clk);
 		return ret;
+	}
 
 	hw_version = readl(ctlr->iobase + HISI_I2C_VERSION);
 	dev_info(ctlr->dev, "speed mode is %s. hw version 0x%x\n",
-- 
2.31.GIT