i2c: designware: Add i2c bus locking support

Adds support for acquiring and releasing a hardware bus lock in the i2c
designware core transfer function. This is needed for i2c bus controllers
that are shared with but not controlled by the kernel.

Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

2 files changed, 32 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index e2799483dc45..fbb48fb138e7 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -285,6 +285,15 @@ int i2c_dw_init(struct dw_i2c_dev *dev)
         u32 hcnt, lcnt;
         u32 reg;
         u32 sda_falling_time, scl_falling_time;
+        int ret;
+
+        if (dev->acquire_lock) {
+                ret = dev->acquire_lock(dev);
+                if (ret) {
+                        dev_err(dev->dev, "couldn't acquire bus ownership\n");
+                        return ret;
+                }
+        }
 
         input_clock_khz = dev->get_clk_rate_khz(dev);
 
@@ -298,6 +307,8 @@ int i2c_dw_init(struct dw_i2c_dev *dev)
         } else if (reg != DW_IC_COMP_TYPE_VALUE) {
                 dev_err(dev->dev, "Unknown Synopsys component type: "
                         "0x%08x\n", reg);
+                if (dev->release_lock)
+                        dev->release_lock(dev);
                 return -ENODEV;
         }
 
@@ -364,6 +375,9 @@ int i2c_dw_init(struct dw_i2c_dev *dev)
 
         /* configure the i2c master */
         dw_writel(dev, dev->master_cfg , DW_IC_CON);
+
+        if (dev->release_lock)
+                dev->release_lock(dev);
         return 0;
 }
 EXPORT_SYMBOL_GPL(i2c_dw_init);
@@ -627,6 +641,14 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
         dev->abort_source = 0;
         dev->rx_outstanding = 0;
 
+        if (dev->acquire_lock) {
+                ret = dev->acquire_lock(dev);
+                if (ret) {
+                        dev_err(dev->dev, "couldn't acquire bus ownership\n");
+                        goto done_nolock;
+                }
+        }
+
         ret = i2c_dw_wait_bus_not_busy(dev);
         if (ret < 0)
                 goto done;
@@ -672,6 +694,10 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
         ret = -EIO;
 
 done:
+        if (dev->release_lock)
+                dev->release_lock(dev);
+
+done_nolock:
         pm_runtime_mark_last_busy(dev->dev);
         pm_runtime_put_autosuspend(dev->dev);
         mutex_unlock(&dev->lock);
diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 5a410ef17abd..ef8ba839e2d3 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -61,6 +61,9 @@
  * @ss_lcnt: standard speed LCNT value
  * @fs_hcnt: fast speed HCNT value
  * @fs_lcnt: fast speed LCNT value
+ * @acquire_lock: function to acquire a hardware lock on the bus
+ * @release_lock: function to release a hardware lock on the bus
+ * @pm_runtime_disabled: true if pm runtime is disabled
  *
  * HCNT and LCNT parameters can be used if the platform knows more accurate
  * values than the one computed based only on the input clock frequency.
@@ -101,6 +104,9 @@ struct dw_i2c_dev {
         u16                     ss_lcnt;
         u16                     fs_hcnt;
         u16                     fs_lcnt;
+        int                     (*acquire_lock)(struct dw_i2c_dev *dev);
+        void                    (*release_lock)(struct dw_i2c_dev *dev);
+        bool                    pm_runtime_disabled;
 };
 
 #define ACCESS_SWAP             0x00000001