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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: 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>
This commit is contained in:
David Box 2015-01-15 01:12:16 -08:00 committed by Wolfram Sang
parent 72f0271576
commit c0601d285e
2 changed files with 32 additions and 0 deletions
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26
drivers/i2c/busses/i2c-designware-core.c
View File

@ -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);

6
drivers/i2c/busses/i2c-designware-core.h
View File

@ -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