drm/radeon/kms: add hw_i2c module option

Turn off hw i2c by default except for mm i2c which
is hw only until we sort out the remaining prescale
issues on older chips.  hw i2c can be enabled with
hw_i2c=1.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/radeon_drv.c b/drivers/gpu/drm/radeon/radeon_drv.c
index 6fd511e..055a517 100644
--- a/drivers/gpu/drm/radeon/radeon_drv.c
+++ b/drivers/gpu/drm/radeon/radeon_drv.c
@@ -93,6 +93,7 @@
 int radeon_dynpm = -1;
 int radeon_audio = 1;
 int radeon_disp_priority = 0;
+int radeon_hw_i2c = 0;
 
 MODULE_PARM_DESC(no_wb, "Disable AGP writeback for scratch registers");
 module_param_named(no_wb, radeon_no_wb, int, 0444);
@@ -139,6 +140,9 @@
 MODULE_PARM_DESC(disp_priority, "Display Priority (0 = auto, 1 = normal, 2 = high)");
 module_param_named(disp_priority, radeon_disp_priority, int, 0444);
 
+MODULE_PARM_DESC(hw_i2c, "hw i2c engine enable (0 = disable)");
+module_param_named(hw_i2c, radeon_hw_i2c, int, 0444);
+
 static int radeon_suspend(struct drm_device *dev, pm_message_t state)
 {
 	drm_radeon_private_t *dev_priv = dev->dev_private;