[PATCH v4 1/3] bus: mhi: core: Introduce internal register poll helper function

[Bhaumik Bhatt <bbhatt@codeaurora.org>]

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 <bbhatt@codeaurora.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 6f80ec3..005286b 100644
--- a/drivers/bus/mhi/core/internal.h
+++ b/drivers/bus/mhi/core/internal.h
@@ -643,6 +643,9 @@ 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 4e0131b..7c7f41a 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;
+
+		udelay(delayus);
+	}
+
+	return -ENOENT;
+}
+
 void mhi_write_reg(struct mhi_controller *mhi_cntrl, void __iomem *base,
 		   u32 offset, u32 val)
 {
-- 
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