[PATCH v6 1/2] bus: mhi: core: Introduce internal register poll helper function

[Bhaumik Bhatt]

Introduce helper function to allow MHI core driver to poll for
a value in a register field. This helps reach a common path to
read and poll register values along with a retry time interval.

Signed-off-by: Bhaumik Bhatt <bbh...@codeaurora.org>
Reviewed-by: Loic Poulain <loic.poul...@linaro.org>
---
 drivers/bus/mhi/core/internal.h |  3 +++
 drivers/bus/mhi/core/main.c     | 23 +++++++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/drivers/bus/mhi/core/internal.h b/drivers/bus/mhi/core/internal.h
index 7aa5cfd..e690f15 100644
--- a/drivers/bus/mhi/core/internal.h
+++ b/drivers/bus/mhi/core/internal.h
@@ -646,6 +646,9 @@ int __must_check mhi_read_reg(struct mhi_controller 
*mhi_cntrl,
 int __must_check mhi_read_reg_field(struct mhi_controller *mhi_cntrl,
                                    void __iomem *base, u32 offset, u32 mask,
                                    u32 shift, u32 *out);
+int __must_check mhi_poll_reg_field(struct mhi_controller *mhi_cntrl,
+                                   void __iomem *base, u32 offset, u32 mask,
+                                   u32 shift, u32 val, u32 delayus);
 void mhi_write_reg(struct mhi_controller *mhi_cntrl, void __iomem *base,
                   u32 offset, u32 val);
 void mhi_write_reg_field(struct mhi_controller *mhi_cntrl, void __iomem *base,
diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index 8b68657..58b8111 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -4,6 +4,7 @@
  *
  */
 
+#include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/dma-direction.h>
 #include <linux/dma-mapping.h>
@@ -37,6 +38,28 @@ int __must_check mhi_read_reg_field(struct mhi_controller 
*mhi_cntrl,
        return 0;
 }
 
+int __must_check mhi_poll_reg_field(struct mhi_controller *mhi_cntrl,
+                                   void __iomem *base, u32 offset,
+                                   u32 mask, u32 shift, u32 val, u32 delayus)
+{
+       int ret;
+       u32 out, retry = (mhi_cntrl->timeout_ms * 1000) / delayus;
+
+       while (retry--) {
+               ret = mhi_read_reg_field(mhi_cntrl, base, offset, mask, shift,
+                                        &out);
+               if (ret)
+                       return ret;
+
+               if (out == val)
+                       return 0;
+
+               fsleep(delayus);
+       }
+
+       return -ETIMEDOUT;
+}
+
 void mhi_write_reg(struct mhi_controller *mhi_cntrl, void __iomem *base,
                   u32 offset, u32 val)
 {
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project