[PATCH 1/3] HID: Intel-thc-hid: Intel-thc: Add API to reset read DMA

[Even Xu <even.xu@intel.com>]

Add a helper function thc_rxdam_reset() to do read DMA reset, it can be
called when fatal DMA error happens.

Signed-off-by: Even Xu <even.xu@intel.com>
---
 .../intel-thc-hid/intel-thc/intel-thc-dma.c   | 37 +++++++++++++++++++
 .../intel-thc-hid/intel-thc/intel-thc-dma.h   |  1 +
 2 files changed, 38 insertions(+)

diff --git a/drivers/hid/intel-thc-hid/intel-thc/intel-thc-dma.c b/drivers/hid/intel-thc-hid/intel-thc/intel-thc-dma.c
index 6ee675e0a738..d771c85dff28 100644
--- a/drivers/hid/intel-thc-hid/intel-thc/intel-thc-dma.c
+++ b/drivers/hid/intel-thc-hid/intel-thc/intel-thc-dma.c
@@ -532,6 +532,43 @@ void thc_dma_unconfigure(struct thc_device *dev)
 }
 EXPORT_SYMBOL_NS_GPL(thc_dma_unconfigure, "INTEL_THC");
 
+/**
+ * thc_rxdma_reset - Reset all read DMA engines
+ *
+ * @dev: The pointer of THC private device context
+ *
+ * This is a helper function to reset RxDMA configure. It's typically used
+ * for RxDMA recovery when fatal error happens.
+ */
+int thc_rxdma_reset(struct thc_device *dev)
+{
+	int ret;
+
+	if (mutex_lock_interruptible(&dev->thc_bus_lock))
+		return -EINTR;
+
+	ret = thc_interrupt_quiesce(dev, true);
+	if (ret) {
+		dev_err_once(dev->dev, "Quiesce interrupt failed during RxDMA reset\n");
+		goto end;
+	}
+
+	thc_dma_unconfigure(dev);
+
+	ret = thc_dma_configure(dev);
+	if (ret) {
+		dev_err_once(dev->dev, "Re-config DMA failed during RxDMA reset\n");
+		goto end;
+	}
+
+	thc_interrupt_quiesce(dev, false);
+
+end:
+	mutex_unlock(&dev->thc_bus_lock);
+	return ret;
+}
+EXPORT_SYMBOL_NS_GPL(thc_rxdma_reset, "INTEL_THC");
+
 static int thc_wait_for_dma_pause(struct thc_device *dev, enum thc_dma_channel channel)
 {
 	u32 ctrl_reg, sts_reg, sts;
diff --git a/drivers/hid/intel-thc-hid/intel-thc/intel-thc-dma.h b/drivers/hid/intel-thc-hid/intel-thc/intel-thc-dma.h
index 541d33995baf..715423453a9d 100644
--- a/drivers/hid/intel-thc-hid/intel-thc/intel-thc-dma.h
+++ b/drivers/hid/intel-thc-hid/intel-thc/intel-thc-dma.h
@@ -145,6 +145,7 @@ int  thc_dma_allocate(struct thc_device *dev);
 int  thc_dma_configure(struct thc_device *dev);
 void thc_dma_unconfigure(struct thc_device *dev);
 void thc_dma_release(struct thc_device *dev);
+int  thc_rxdma_reset(struct thc_device *dev);
 int  thc_rxdma_read(struct thc_device *dev, enum thc_dma_channel dma_channel,
 		    void *read_buff, size_t *read_len, int *read_finished);
 int  thc_swdma_read(struct thc_device *dev, void *write_buff, size_t write_len,
-- 
2.43.0