2 files changed, 57 insertions, 10 deletions

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index b522eb6e59a4..3da1af46625c 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -1807,6 +1807,7 @@ enum skl_disp_power_wells {
 #define   GMBUS_CYCLE_INDEX     (2<<25)
 #define   GMBUS_CYCLE_STOP      (4<<25)
 #define   GMBUS_BYTE_COUNT_SHIFT 16
+#define   GMBUS_BYTE_COUNT_MAX   256U
 #define   GMBUS_SLAVE_INDEX_SHIFT 8
 #define   GMBUS_SLAVE_ADDR_SHIFT 1
 #define   GMBUS_SLAVE_READ      (1<<0)
diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c
index b31088a551f2..56e437e31580 100644
--- a/drivers/gpu/drm/i915/intel_i2c.c
+++ b/drivers/gpu/drm/i915/intel_i2c.c
@@ -270,18 +270,17 @@ gmbus_wait_idle(struct drm_i915_private *dev_priv)
 }
 
 static int
-gmbus_xfer_read(struct drm_i915_private *dev_priv, struct i2c_msg *msg,
-                u32 gmbus1_index)
+gmbus_xfer_read_chunk(struct drm_i915_private *dev_priv,
+                      unsigned short addr, u8 *buf, unsigned int len,
+                      u32 gmbus1_index)
 {
         int reg_offset = dev_priv->gpio_mmio_base;
-        u16 len = msg->len;
-        u8 *buf = msg->buf;
 
         I915_WRITE(GMBUS1 + reg_offset,
                    gmbus1_index |
                    GMBUS_CYCLE_WAIT |
                    (len << GMBUS_BYTE_COUNT_SHIFT) |
-                   (msg->addr << GMBUS_SLAVE_ADDR_SHIFT) |
+                   (addr << GMBUS_SLAVE_ADDR_SHIFT) |
                    GMBUS_SLAVE_READ | GMBUS_SW_RDY);
         while (len) {
                 int ret;
@@ -303,11 +302,35 @@ gmbus_xfer_read(struct drm_i915_private *dev_priv, struct i2c_msg *msg,
 }
 
 static int
-gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg)
+gmbus_xfer_read(struct drm_i915_private *dev_priv, struct i2c_msg *msg,
+                u32 gmbus1_index)
 {
-        int reg_offset = dev_priv->gpio_mmio_base;
-        u16 len = msg->len;
         u8 *buf = msg->buf;
+        unsigned int rx_size = msg->len;
+        unsigned int len;
+        int ret;
+
+        do {
+                len = min(rx_size, GMBUS_BYTE_COUNT_MAX);
+
+                ret = gmbus_xfer_read_chunk(dev_priv, msg->addr,
+                                            buf, len, gmbus1_index);
+                if (ret)
+                        return ret;
+
+                rx_size -= len;
+                buf += len;
+        } while (rx_size != 0);
+
+        return 0;
+}
+
+static int
+gmbus_xfer_write_chunk(struct drm_i915_private *dev_priv,
+                       unsigned short addr, u8 *buf, unsigned int len)
+{
+        int reg_offset = dev_priv->gpio_mmio_base;
+        unsigned int chunk_size = len;
         u32 val, loop;
 
         val = loop = 0;
@@ -319,8 +342,8 @@ gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg)
         I915_WRITE(GMBUS3 + reg_offset, val);
         I915_WRITE(GMBUS1 + reg_offset,
                    GMBUS_CYCLE_WAIT |
-                   (msg->len << GMBUS_BYTE_COUNT_SHIFT) |
-                   (msg->addr << GMBUS_SLAVE_ADDR_SHIFT) |
+                   (chunk_size << GMBUS_BYTE_COUNT_SHIFT) |
+                   (addr << GMBUS_SLAVE_ADDR_SHIFT) |
                    GMBUS_SLAVE_WRITE | GMBUS_SW_RDY);
         while (len) {
                 int ret;
@@ -337,6 +360,29 @@ gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg)
                 if (ret)
                         return ret;
         }
+
+        return 0;
+}
+
+static int
+gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg)
+{
+        u8 *buf = msg->buf;
+        unsigned int tx_size = msg->len;
+        unsigned int len;
+        int ret;
+
+        do {
+                len = min(tx_size, GMBUS_BYTE_COUNT_MAX);
+
+                ret = gmbus_xfer_write_chunk(dev_priv, msg->addr, buf, len);
+                if (ret)
+                        return ret;
+
+                buf += len;
+                tx_size -= len;
+        } while (tx_size != 0);
+
         return 0;
 }