i2c: mv64xxx: Set bus frequency to 100kHz if clock-frequency is not provided

This commit adds checking whether clock-frequency property acquisition
has succeeded. If not, the frequency is set to 100kHz by default.

The Device Tree binding documentation is updated accordingly.

Based on the intials patches from Zbigniew Bodek

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Zbigniew Bodek <zbb@semihalf.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

2 files changed, 10 insertions, 2 deletions

diff --git a/Documentation/devicetree/bindings/i2c/i2c-mv64xxx.txt b/Documentation/devicetree/bindings/i2c/i2c-mv64xxx.txt
index f46d928aa73d..a1ee681942cc 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-mv64xxx.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-mv64xxx.txt
@@ -6,7 +6,11 @@ Required properties :
  - reg             : Offset and length of the register set for the device
  - compatible      : Should be "marvell,mv64xxx-i2c"
  - interrupts      : The interrupt number
- - clock-frequency : Desired I2C bus clock frequency in Hz.
+
+Optional properties :
+
+ - clock-frequency : Desired I2C bus clock frequency in Hz. If not set the
+default frequency is 100kHz
 
 Examples:
 
diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
index ed854573b427..b1f42bf40963 100644
--- a/drivers/i2c/busses/i2c-mv64xxx.c
+++ b/drivers/i2c/busses/i2c-mv64xxx.c
@@ -578,7 +578,11 @@ mv64xxx_of_config(struct mv64xxx_i2c_data *drv_data,
                 goto out;
         }
         tclk = clk_get_rate(drv_data->clk);
-        of_property_read_u32(np, "clock-frequency", &bus_freq);
+
+        rc = of_property_read_u32(np, "clock-frequency", &bus_freq);
+        if (rc)
+                bus_freq = 100000; /* 100kHz by default */
+
         if (!mv64xxx_find_baud_factors(bus_freq, tclk,
                                        &drv_data->freq_n, &drv_data->freq_m)) {
                 rc = -EINVAL;