Instead of rolling our own custom quirk_xfer function, use the bit_algo
pre_xfer and post_xfer functions to setup and teardown bit-banged
i2c transactions.

gmbus_xfer uses .force_bit to determine which i2c_algorithm to use,
either i2c_bit_algo.master_xfer or its own.  So, Similarly, let gmbus_func
use .force_bit to determine which i2c functionalities are available,
either i2c_bit_algo.functionality, or its own.

Signed-off-by: Daniel Kurtz <djkurtz at chromium.org>
---
 drivers/gpu/drm/i915/intel_i2c.c |   72 +++++++++++++++++++++++--------------
 1 files changed, 45 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c
index 54f85a1..ae08a08 100644
--- a/drivers/gpu/drm/i915/intel_i2c.c
+++ b/drivers/gpu/drm/i915/intel_i2c.c
@@ -137,6 +137,35 @@ static void set_data(void *data, int state_high)
        POSTING_READ(bus->gpio_reg);
 }

+static int
+intel_gpio_pre_xfer(struct i2c_adapter *adapter)
+{
+       struct intel_gmbus *bus = container_of(adapter,
+                                              struct intel_gmbus,
+                                              adapter);
+       struct drm_i915_private *dev_priv = bus->dev_priv;
+
+       intel_i2c_reset(dev_priv->dev);
+       intel_i2c_quirk_set(dev_priv, true);
+       set_data(bus, 1);
+       set_clock(bus, 1);
+       udelay(I2C_RISEFALL_TIME);
+       return 0;
+}
+
+static void
+intel_gpio_post_xfer(struct i2c_adapter *adapter)
+{
+       struct intel_gmbus *bus = container_of(adapter,
+                                              struct intel_gmbus,
+                                              adapter);
+       struct drm_i915_private *dev_priv = bus->dev_priv;
+
+       set_data(bus, 1);
+       set_clock(bus, 1);
+       intel_i2c_quirk_set(dev_priv, false);
+}
+
 static bool
 intel_gpio_setup(struct intel_gmbus *bus, u32 pin)
 {
@@ -166,6 +195,8 @@ intel_gpio_setup(struct intel_gmbus *bus, u32 pin)
        algo->setscl = set_clock;
        algo->getsda = get_data;
        algo->getscl = get_clock;
+       algo->pre_xfer = intel_gpio_pre_xfer;
+       algo->post_xfer = intel_gpio_post_xfer;
        algo->udelay = I2C_RISEFALL_TIME;
        algo->timeout = usecs_to_jiffies(2200);
        algo->data = bus;
@@ -174,30 +205,6 @@ intel_gpio_setup(struct intel_gmbus *bus, u32 pin)
 }

 static int
-intel_i2c_quirk_xfer(struct intel_gmbus *bus,
-                    struct i2c_msg *msgs,
-                    int num)
-{
-       struct drm_i915_private *dev_priv = bus->dev_priv;
-       int ret;
-
-       intel_i2c_reset(dev_priv->dev);
-
-       intel_i2c_quirk_set(dev_priv, true);
-       set_data(bus, 1);
-       set_clock(bus, 1);
-       udelay(I2C_RISEFALL_TIME);
-
-       ret = i2c_bit_algo.master_xfer(&bus->adapter, msgs, num);
-
-       set_data(bus, 1);
-       set_clock(bus, 1);
-       intel_i2c_quirk_set(dev_priv, false);
-
-       return ret;
-}
-
-static int
 gmbus_xfer(struct i2c_adapter *adapter,
           struct i2c_msg *msgs,
           int num)
@@ -211,7 +218,7 @@ gmbus_xfer(struct i2c_adapter *adapter,
        mutex_lock(&dev_priv->gmbus_mutex);

        if (bus->force_bit) {
-               ret = intel_i2c_quirk_xfer(bus, msgs, num);
+               ret = i2c_bit_algo.master_xfer(adapter, msgs, num);
                goto out;
        }

@@ -325,8 +332,9 @@ timeout:
                ret = -EIO;
        } else {
                bus->force_bit = true;
-               ret = intel_i2c_quirk_xfer(bus, msgs, num);
+               ret = i2c_bit_algo.master_xfer(adapter, msgs, num);
        }
+
 out:
        mutex_unlock(&dev_priv->gmbus_mutex);
        return ret;
@@ -334,11 +342,21 @@ out:

 static u32 gmbus_func(struct i2c_adapter *adapter)
 {
-       return i2c_bit_algo.functionality(adapter) &
+       struct intel_gmbus *bus = container_of(adapter,
+                                              struct intel_gmbus,
+                                              adapter);
+       struct drm_i915_private *dev_priv = bus->dev_priv;
+       u32 func;
+
+       mutex_lock(&dev_priv->gmbus_mutex);
+       func = bus->force_bit ? i2c_bit_algo.functionality(adapter) :
                (I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
                /* I2C_FUNC_10BIT_ADDR | */
                I2C_FUNC_SMBUS_READ_BLOCK_DATA |
                I2C_FUNC_SMBUS_BLOCK_PROC_CALL);
+       mutex_unlock(&dev_priv->gmbus_mutex);
+
+       return func;
 }

 static const struct i2c_algorithm gmbus_algorithm = {
-- 
1.7.7.3

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