[PATCH] i2c: designware: deduce speed mode from device tree setting
From: atull
Date: Tue Aug 19 2014 - 16:24:13 EST
From: Alan Tull <atull@xxxxxxxxxxxxxxxxxxxxx>
Use the documented, but unimplemented "clock-frequency"
Device Tree setting as a guide on whether to set the speed
mode bits in DW_IC_CON to standard or fast i2c mode.
Previously, the driver was hardwired to fast mode. Default
to fast mode if the "clock-frequency" property is not present
for backwards compatiblity.
Signed-off-by: Alan Tull <atull@xxxxxxxxxxxxxxxxxxxxx>
---
drivers/i2c/busses/i2c-designware-platdrv.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index bc87733..18cd3d9 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -122,7 +122,8 @@ static int dw_i2c_probe(struct platform_device *pdev)
struct dw_i2c_dev *dev;
struct i2c_adapter *adap;
struct resource *mem;
- int irq, r;
+ int irq, r, ret, speed = DW_IC_CON_SPEED_FAST;
+ u32 bus_rate;
irq = platform_get_irq(pdev, 0);
if (irq < 0) {
@@ -167,6 +168,11 @@ static int dw_i2c_probe(struct platform_device *pdev)
of_property_read_u32(pdev->dev.of_node,
"i2c-scl-falling-time-ns",
&dev->scl_falling_time);
+
+ ret = of_property_read_u32(pdev->dev.of_node,
+ "clock-frequency", &bus_rate);
+ if (!ret && (bus_rate <= 100000))
+ speed = DW_IC_CON_SPEED_STD;
}
dev->functionality =
@@ -177,7 +183,7 @@ static int dw_i2c_probe(struct platform_device *pdev)
I2C_FUNC_SMBUS_WORD_DATA |
I2C_FUNC_SMBUS_I2C_BLOCK;
dev->master_cfg = DW_IC_CON_MASTER | DW_IC_CON_SLAVE_DISABLE |
- DW_IC_CON_RESTART_EN | DW_IC_CON_SPEED_FAST;
+ DW_IC_CON_RESTART_EN | speed;
/* Try first if we can configure the device from ACPI */
r = dw_i2c_acpi_configure(pdev);
--
1.7.9.5
--
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