bus: mhi: host: Add a new API for getting channel doorbell offset

Some controllers may want to access a specific doorbell register. Hence add
a new API that reads the CHDBOFF register and returns the offset of the
doorbell registers from MMIO base, so that the controller can calculate the
address of the specific doorbell register by adding the register offset
with doorbell offset and MMIO base address.

Signed-off-by: Qiang Yu <quic_qianyu@quicinc.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Link: https://lore.kernel.org/r/1713928915-18229-3-git-send-email-quic_qianyu@quicinc.com
[mani: reworded commit message and Kdoc]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

diff --git a/drivers/bus/mhi/host/init.c b/drivers/bus/mhi/host/init.c
index 7104c18569876265bb9c9b09653b46657b7f54bb..173f79918741b6fd00643590ae3a681a5337ace0 100644 (file)
--- a/drivers/bus/mhi/host/init.c
+++ b/drivers/bus/mhi/host/init.c
@@ -541,11 +541,9 @@ int mhi_init_mmio(struct mhi_controller *mhi_cntrl)
        dev_dbg(dev, "Initializing MHI registers\n");
 
        /* Read channel db offset */
-       ret = mhi_read_reg(mhi_cntrl, base, CHDBOFF, &val);
-       if (ret) {
-               dev_err(dev, "Unable to read CHDBOFF register\n");
-               return -EIO;
-       }
+       ret = mhi_get_channel_doorbell_offset(mhi_cntrl, &val);
+       if (ret)
+               return ret;
 
        if (val >= mhi_cntrl->reg_len - (8 * MHI_DEV_WAKE_DB)) {
                dev_err(dev, "CHDB offset: 0x%x is out of range: 0x%zx\n",

diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
index 15d657af9b5b8685bfa0a70b0c4dd2c498c3bf06..4de75674f19350ef5fe02105bd4cc4539a76966e 100644 (file)
--- a/drivers/bus/mhi/host/main.c
+++ b/drivers/bus/mhi/host/main.c
@@ -1691,3 +1691,19 @@ void mhi_unprepare_from_transfer(struct mhi_device *mhi_dev)
        }
 }
 EXPORT_SYMBOL_GPL(mhi_unprepare_from_transfer);
+
+int mhi_get_channel_doorbell_offset(struct mhi_controller *mhi_cntrl, u32 *chdb_offset)
+{
+       struct device *dev = &mhi_cntrl->mhi_dev->dev;
+       void __iomem *base = mhi_cntrl->regs;
+       int ret;
+
+       ret = mhi_read_reg(mhi_cntrl, base, CHDBOFF, chdb_offset);
+       if (ret) {
+               dev_err(dev, "Unable to read CHDBOFF register\n");
+               return -EIO;
+       }
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(mhi_get_channel_doorbell_offset);

diff --git a/include/linux/mhi.h b/include/linux/mhi.h
index d968e1ab44dc503ed9b243c55b1089417825fedf..b573f15762f85a643d06a49de762e0b463699696 100644 (file)
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -816,4 +816,13 @@ int mhi_queue_skb(struct mhi_device *mhi_dev, enum dma_data_direction dir,
  */
 bool mhi_queue_is_full(struct mhi_device *mhi_dev, enum dma_data_direction dir);
 
+/**
+ * mhi_get_channel_doorbell_offset - Get the channel doorbell offset
+ * @mhi_cntrl: MHI controller
+ * @chdb_offset: Read channel doorbell offset
+ *
+ * Return: 0 if the read succeeds, a negative error code otherwise
+ */
+int mhi_get_channel_doorbell_offset(struct mhi_controller *mhi_cntrl, u32 *chdb_offset);
+
 #endif /* _MHI_H_ */