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Commit c0601d28 authored by David Box's avatar David Box Committed by Wolfram Sang
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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: default avatarDavid E. Box <david.e.box@linux.intel.com>
Reviewed-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
parent 72f02715

drivers/i2c/busses/i2c-designware-core.c

+26 −0
Original line number Diff line number Diff line
@@ -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);

drivers/i2c/busses/i2c-designware-core.h

+6 −0
Original line number Diff line number Diff line
@@ -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