i2c: designware: Do not require clock when SSCN and FFCN are provided

The current driver uses input clock source frequency to calculate
values for [SS|FS]_[HC|LC] registers. However, when booting ACPI, we do not
currently have a good way to provide the frequency information.
Instead, we can leverage the SSCN and FFCN ACPI methods, which can be used
to directly provide these values. So, the clock information should
no longer be required during probing.

However, since clk can be invalid, additional checks must be done where
we are making use of it.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Tested-by: Loc Ho <lho@apm.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

1 files changed, 20 insertions, 11 deletions

diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 8ffc36b8a6d3..965512c3b1cf 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -128,6 +128,18 @@ static inline int dw_i2c_acpi_configure(struct platform_device *pdev)
 }
 #endif
 
+static int i2c_dw_plat_prepare_clk(struct dw_i2c_dev *i_dev, bool prepare)
+{
+	if (IS_ERR(i_dev->clk))
+		return PTR_ERR(i_dev->clk);
+
+	if (prepare)
+		return clk_prepare_enable(i_dev->clk);
+
+	clk_disable_unprepare(i_dev->clk);
+	return 0;
+}
+
 static int dw_i2c_plat_probe(struct platform_device *pdev)
 {
 	struct dw_i2c_dev *dev;
@@ -205,16 +217,13 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
 			DW_IC_CON_RESTART_EN | DW_IC_CON_SPEED_FAST;
 
 	dev->clk = devm_clk_get(&pdev->dev, NULL);
-	dev->get_clk_rate_khz = i2c_dw_get_clk_rate_khz;
-	if (IS_ERR(dev->clk))
-		return PTR_ERR(dev->clk);
-	clk_prepare_enable(dev->clk);
+	if (!i2c_dw_plat_prepare_clk(dev, true)) {
+		dev->get_clk_rate_khz = i2c_dw_get_clk_rate_khz;
 
-	if (!dev->sda_hold_time && ht) {
-		u32 ic_clk = dev->get_clk_rate_khz(dev);
-
-		dev->sda_hold_time = div_u64((u64)ic_clk * ht + 500000,
-					     1000000);
+		if (!dev->sda_hold_time && ht)
+			dev->sda_hold_time = div_u64(
+				(u64)dev->get_clk_rate_khz(dev) * ht + 500000,
+				1000000);
 	}
 
 	if (!dev->tx_fifo_depth) {
@@ -297,7 +306,7 @@ static int dw_i2c_plat_suspend(struct device *dev)
 	struct dw_i2c_dev *i_dev = platform_get_drvdata(pdev);
 
 	i2c_dw_disable(i_dev);
-	clk_disable_unprepare(i_dev->clk);
+	i2c_dw_plat_prepare_clk(i_dev, false);
 
 	return 0;
 }
@@ -307,7 +316,7 @@ static int dw_i2c_plat_resume(struct device *dev)
 	struct platform_device *pdev = to_platform_device(dev);
 	struct dw_i2c_dev *i_dev = platform_get_drvdata(pdev);
 
-	clk_prepare_enable(i_dev->clk);
+	i2c_dw_plat_prepare_clk(i_dev, true);
 
 	if (!i_dev->pm_runtime_disabled)
 		i2c_dw_init(i_dev);