drm/radeon: add a i2c bus mutex

The i2c and aux buses use the same pads so add
a mutex to protect access to the pads.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>

4 files changed, 37 insertions, 8 deletions

diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
index bc0119fb6c12..330f8df65b09 100644
--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -95,9 +95,12 @@ static int radeon_process_aux_ch(struct radeon_i2c_chan *chan,
         int index = GetIndexIntoMasterTable(COMMAND, ProcessAuxChannelTransaction);
         unsigned char *base;
         int recv_bytes;
+        int r = 0;
 
         memset(&args, 0, sizeof(args));
 
+        mutex_lock(&chan->mutex);
+
         base = (unsigned char *)(rdev->mode_info.atom_context->scratch + 1);
 
         radeon_atom_copy_swap(base, send, send_bytes, true);
@@ -117,19 +120,22 @@ static int radeon_process_aux_ch(struct radeon_i2c_chan *chan,
         /* timeout */
         if (args.v1.ucReplyStatus == 1) {
                 DRM_DEBUG_KMS("dp_aux_ch timeout\n");
-                return -ETIMEDOUT;
+                r = -ETIMEDOUT;
+                goto done;
         }
 
         /* flags not zero */
         if (args.v1.ucReplyStatus == 2) {
                 DRM_DEBUG_KMS("dp_aux_ch flags not zero\n");
-                return -EBUSY;
+                r = -EBUSY;
+                goto done;
         }
 
         /* error */
         if (args.v1.ucReplyStatus == 3) {
                 DRM_DEBUG_KMS("dp_aux_ch error\n");
-                return -EIO;
+                r = -EIO;
+                goto done;
         }
 
         recv_bytes = args.v1.ucDataOutLen;
@@ -139,7 +145,11 @@ static int radeon_process_aux_ch(struct radeon_i2c_chan *chan,
         if (recv && recv_size)
                 radeon_atom_copy_swap(recv, base + 16, recv_bytes, false);
 
-        return recv_bytes;
+        r = recv_bytes;
+done:
+        mutex_unlock(&chan->mutex);
+
+        return r;
 }
 
 #define BARE_ADDRESS_SIZE 3
diff --git a/drivers/gpu/drm/radeon/atombios_i2c.c b/drivers/gpu/drm/radeon/atombios_i2c.c
index b5162c3b6111..9c570fb15b8c 100644
--- a/drivers/gpu/drm/radeon/atombios_i2c.c
+++ b/drivers/gpu/drm/radeon/atombios_i2c.c
@@ -43,15 +43,19 @@ static int radeon_process_i2c_ch(struct radeon_i2c_chan *chan,
         int index = GetIndexIntoMasterTable(COMMAND, ProcessI2cChannelTransaction);
         unsigned char *base;
         u16 out = cpu_to_le16(0);
+        int r = 0;
 
         memset(&args, 0, sizeof(args));
 
+        mutex_lock(&chan->mutex);
+
         base = (unsigned char *)rdev->mode_info.atom_context->scratch;
 
         if (flags & HW_I2C_WRITE) {
                 if (num > ATOM_MAX_HW_I2C_WRITE) {
                         DRM_ERROR("hw i2c: tried to write too many bytes (%d vs 3)\n", num);
-                        return -EINVAL;
+                        r = -EINVAL;
+                        goto done;
                 }
                 if (buf == NULL)
                         args.ucRegIndex = 0;
@@ -65,7 +69,8 @@ static int radeon_process_i2c_ch(struct radeon_i2c_chan *chan,
         } else {
                 if (num > ATOM_MAX_HW_I2C_READ) {
                         DRM_ERROR("hw i2c: tried to read too many bytes (%d vs 255)\n", num);
-                        return -EINVAL;
+                        r = -EINVAL;
+                        goto done;
                 }
                 args.ucRegIndex = 0;
                 args.lpI2CDataOut = 0;
@@ -82,13 +87,17 @@ static int radeon_process_i2c_ch(struct radeon_i2c_chan *chan,
         /* error */
         if (args.ucStatus != HW_ASSISTED_I2C_STATUS_SUCCESS) {
                 DRM_DEBUG_KMS("hw_i2c error\n");
-                return -EIO;
+                r = -EIO;
+                goto done;
         }
 
         if (!(flags & HW_I2C_WRITE))
                 radeon_atom_copy_swap(buf, base, num, false);
 
-        return 0;
+done:
+        mutex_unlock(&chan->mutex);
+
+        return r;
 }
 
 int radeon_atom_hw_i2c_xfer(struct i2c_adapter *i2c_adap,
diff --git a/drivers/gpu/drm/radeon/radeon_i2c.c b/drivers/gpu/drm/radeon/radeon_i2c.c
index 7b944142a9fd..427ee4d6d0b5 100644
--- a/drivers/gpu/drm/radeon/radeon_i2c.c
+++ b/drivers/gpu/drm/radeon/radeon_i2c.c
@@ -94,6 +94,8 @@ static int pre_xfer(struct i2c_adapter *i2c_adap)
         struct radeon_i2c_bus_rec *rec = &i2c->rec;
         uint32_t temp;
 
+        mutex_lock(&i2c->mutex);
+
         /* RV410 appears to have a bug where the hw i2c in reset
          * holds the i2c port in a bad state - switch hw i2c away before
          * doing DDC - do this for all r200s/r300s/r400s for safety sake
@@ -170,6 +172,8 @@ static void post_xfer(struct i2c_adapter *i2c_adap)
         temp = RREG32(rec->mask_data_reg) & ~rec->mask_data_mask;
         WREG32(rec->mask_data_reg, temp);
         temp = RREG32(rec->mask_data_reg);
+
+        mutex_unlock(&i2c->mutex);
 }
 
 static int get_clock(void *i2c_priv)
@@ -813,6 +817,8 @@ static int radeon_hw_i2c_xfer(struct i2c_adapter *i2c_adap,
         struct radeon_i2c_bus_rec *rec = &i2c->rec;
         int ret = 0;
 
+        mutex_lock(&i2c->mutex);
+
         switch (rdev->family) {
         case CHIP_R100:
         case CHIP_RV100:
@@ -879,6 +885,8 @@ static int radeon_hw_i2c_xfer(struct i2c_adapter *i2c_adap,
                 break;
         }
 
+        mutex_unlock(&i2c->mutex);
+
         return ret;
 }
 
@@ -919,6 +927,7 @@ struct radeon_i2c_chan *radeon_i2c_create(struct drm_device *dev,
         i2c->adapter.dev.parent = &dev->pdev->dev;
         i2c->dev = dev;
         i2c_set_adapdata(&i2c->adapter, i2c);
+        mutex_init(&i2c->mutex);
         if (rec->mm_i2c ||
             (rec->hw_capable &&
              radeon_hw_i2c &&
diff --git a/drivers/gpu/drm/radeon/radeon_mode.h b/drivers/gpu/drm/radeon/radeon_mode.h
index 6ddf31a2d34e..b265a8b95fe6 100644
--- a/drivers/gpu/drm/radeon/radeon_mode.h
+++ b/drivers/gpu/drm/radeon/radeon_mode.h
@@ -191,6 +191,7 @@ struct radeon_i2c_chan {
         struct radeon_i2c_bus_rec rec;
         struct drm_dp_aux aux;
         bool has_aux;
+        struct mutex mutex;
 };
 
 /* mostly for macs, but really any system without connector tables */