drm/radeon/kms/dce3+: add support for hw i2c using atom
Starting with DCE3 hardware, atom contains a general purpose
ProcessI2cChannelTransaction similar to ProcessAuxChannelTransaction.
Add an implementation using the atom tables for DCE3+ hardware.
This should be a little less CPU intensive than bit banging and
may work better in certain cases.
Enable it by setting the radeon hw_i2c module parameter to 1. E.g.,
radeon.hw_i2c=1
on the kernel command line in grub.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/radeon_i2c.c b/drivers/gpu/drm/radeon/radeon_i2c.c
index c47f222f..3265a7a 100644
--- a/drivers/gpu/drm/radeon/radeon_i2c.c
+++ b/drivers/gpu/drm/radeon/radeon_i2c.c
@@ -30,6 +30,10 @@
#include "radeon.h"
#include "atom.h"
+extern int radeon_atom_hw_i2c_xfer(struct i2c_adapter *i2c_adap,
+ struct i2c_msg *msgs, int num);
+extern u32 radeon_atom_hw_i2c_func(struct i2c_adapter *adap);
+
/**
* radeon_ddc_probe
*
@@ -882,6 +886,11 @@
.functionality = radeon_hw_i2c_func,
};
+static const struct i2c_algorithm radeon_atom_i2c_algo = {
+ .master_xfer = radeon_atom_hw_i2c_xfer,
+ .functionality = radeon_atom_hw_i2c_func,
+};
+
struct radeon_i2c_chan *radeon_i2c_create(struct drm_device *dev,
struct radeon_i2c_bus_rec *rec,
const char *name)
@@ -914,6 +923,18 @@
DRM_ERROR("Failed to register hw i2c %s\n", name);
goto out_free;
}
+ } else if (rec->hw_capable &&
+ radeon_hw_i2c &&
+ ASIC_IS_DCE3(rdev)) {
+ /* hw i2c using atom */
+ snprintf(i2c->adapter.name, sizeof(i2c->adapter.name),
+ "Radeon i2c hw bus %s", name);
+ i2c->adapter.algo = &radeon_atom_i2c_algo;
+ ret = i2c_add_adapter(&i2c->adapter);
+ if (ret) {
+ DRM_ERROR("Failed to register hw i2c %s\n", name);
+ goto out_free;
+ }
} else {
/* set the radeon bit adapter */
snprintf(i2c->adapter.name, sizeof(i2c->adapter.name),