[PATCH v1 1/2] bus: mhi: core: Bail on writing register fields if read fails

[Bhaumik Bhatt <bbhatt@codeaurora.org>]

Helper API to write register fields relies on successful reads
of the register/address prior to the write. Bail out if a failure
is seen when reading the register before the actual write is
performed.

Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
---
 drivers/bus/mhi/core/boot.c     | 25 +++++++++++++++++--------
 drivers/bus/mhi/core/init.c     | 24 ++++++++++++++++++------
 drivers/bus/mhi/core/internal.h |  7 ++++---
 drivers/bus/mhi/core/main.c     |  9 ++++++---
 4 files changed, 45 insertions(+), 20 deletions(-)

diff --git a/drivers/bus/mhi/core/boot.c b/drivers/bus/mhi/core/boot.c
index 0a97262..13eacda 100644
--- a/drivers/bus/mhi/core/boot.c
+++ b/drivers/bus/mhi/core/boot.c
@@ -19,8 +19,8 @@
 #include "internal.h"
 
 /* Setup RDDM vector table for RDDM transfer and program RXVEC */
-void mhi_rddm_prepare(struct mhi_controller *mhi_cntrl,
-		      struct image_info *img_info)
+int mhi_rddm_prepare(struct mhi_controller *mhi_cntrl,
+		     struct image_info *img_info)
 {
 	struct mhi_buf *mhi_buf = img_info->mhi_buf;
 	struct bhi_vec_entry *bhi_vec = img_info->bhi_vec;
@@ -28,6 +28,7 @@ void mhi_rddm_prepare(struct mhi_controller *mhi_cntrl,
 	struct device *dev = &mhi_cntrl->mhi_dev->dev;
 	u32 sequence_id;
 	unsigned int i;
+	int ret;
 
 	for (i = 0; i < img_info->entries - 1; i++, mhi_buf++, bhi_vec++) {
 		bhi_vec->dma_addr = mhi_buf->dma_addr;
@@ -45,12 +46,17 @@ void mhi_rddm_prepare(struct mhi_controller *mhi_cntrl,
 	mhi_write_reg(mhi_cntrl, base, BHIE_RXVECSIZE_OFFS, mhi_buf->len);
 	sequence_id = MHI_RANDOM_U32_NONZERO(BHIE_RXVECSTATUS_SEQNUM_BMSK);
 
-	mhi_write_reg_field(mhi_cntrl, base, BHIE_RXVECDB_OFFS,
-			    BHIE_RXVECDB_SEQNUM_BMSK, BHIE_RXVECDB_SEQNUM_SHFT,
-			    sequence_id);
+	ret = mhi_write_reg_field(mhi_cntrl, base, BHIE_RXVECDB_OFFS,
+				  BHIE_RXVECDB_SEQNUM_BMSK,
+				  BHIE_RXVECDB_SEQNUM_SHFT, sequence_id);
+	if (ret) {
+		dev_err(dev, "Failed to write sequence ID for BHIE_RXVECDB\n");
+		return ret;
+	}
 
 	dev_dbg(dev, "Address: %p and len: 0x%zx sequence: %u\n",
 		&mhi_buf->dma_addr, mhi_buf->len, sequence_id);
+	return 0;
 }
 
 /* Collect RDDM buffer during kernel panic */
@@ -202,11 +208,14 @@ static int mhi_fw_load_bhie(struct mhi_controller *mhi_cntrl,
 
 	mhi_write_reg(mhi_cntrl, base, BHIE_TXVECSIZE_OFFS, mhi_buf->len);
 
-	mhi_write_reg_field(mhi_cntrl, base, BHIE_TXVECDB_OFFS,
-			    BHIE_TXVECDB_SEQNUM_BMSK, BHIE_TXVECDB_SEQNUM_SHFT,
-			    sequence_id);
+	ret = mhi_write_reg_field(mhi_cntrl, base, BHIE_TXVECDB_OFFS,
+				  BHIE_TXVECDB_SEQNUM_BMSK,
+				  BHIE_TXVECDB_SEQNUM_SHFT, sequence_id);
 	read_unlock_bh(pm_lock);
 
+	if (ret)
+		return ret;
+
 	/* Wait for the image download to complete */
 	ret = wait_event_timeout(mhi_cntrl->state_event,
 				 MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state) ||
diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
index 5aaca6d..0917465 100644
--- a/drivers/bus/mhi/core/init.c
+++ b/drivers/bus/mhi/core/init.c
@@ -544,10 +544,15 @@ int mhi_init_mmio(struct mhi_controller *mhi_cntrl)
 	mhi_cntrl->mhi_cmd[PRIMARY_CMD_RING].ring.db_addr = base + CRDB_LOWER;
 
 	/* Write to MMIO registers */
-	for (i = 0; reg_info[i].offset; i++)
-		mhi_write_reg_field(mhi_cntrl, base, reg_info[i].offset,
-				    reg_info[i].mask, reg_info[i].shift,
-				    reg_info[i].val);
+	for (i = 0; reg_info[i].offset; i++) {
+		ret = mhi_write_reg_field(mhi_cntrl, base, reg_info[i].offset,
+					  reg_info[i].mask, reg_info[i].shift,
+					  reg_info[i].val);
+		if (ret) {
+			dev_err(dev, "Unable to write to MMIO registers");
+			return ret;
+		}
+	}
 
 	return 0;
 }
@@ -1118,8 +1123,15 @@ int mhi_prepare_for_power_up(struct mhi_controller *mhi_cntrl)
 		 */
 		mhi_alloc_bhie_table(mhi_cntrl, &mhi_cntrl->rddm_image,
 				     mhi_cntrl->rddm_size);
-		if (mhi_cntrl->rddm_image)
-			mhi_rddm_prepare(mhi_cntrl, mhi_cntrl->rddm_image);
+		if (mhi_cntrl->rddm_image) {
+			ret = mhi_rddm_prepare(mhi_cntrl,
+					       mhi_cntrl->rddm_image);
+			if (ret) {
+				mhi_free_bhie_table(mhi_cntrl,
+						    mhi_cntrl->rddm_image);
+				goto error_reg_offset;
+			}
+		}
 	}
 
 	mutex_unlock(&mhi_cntrl->pm_mutex);
diff --git a/drivers/bus/mhi/core/internal.h b/drivers/bus/mhi/core/internal.h
index 721739c..3d17ec3 100644
--- a/drivers/bus/mhi/core/internal.h
+++ b/drivers/bus/mhi/core/internal.h
@@ -663,8 +663,9 @@ int __must_check mhi_poll_reg_field(struct mhi_controller *mhi_cntrl,
 				    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,
-			 u32 offset, u32 mask, u32 shift, u32 val);
+int __must_check mhi_write_reg_field(struct mhi_controller *mhi_cntrl,
+				     void __iomem *base, u32 offset,
+				     u32 mask, u32 shift, u32 val);
 void mhi_ring_er_db(struct mhi_event *mhi_event);
 void mhi_write_db(struct mhi_controller *mhi_cntrl, void __iomem *db_addr,
 		  dma_addr_t db_val);
@@ -678,7 +679,7 @@ int mhi_init_dev_ctxt(struct mhi_controller *mhi_cntrl);
 void mhi_deinit_dev_ctxt(struct mhi_controller *mhi_cntrl);
 int mhi_init_irq_setup(struct mhi_controller *mhi_cntrl);
 void mhi_deinit_free_irq(struct mhi_controller *mhi_cntrl);
-void mhi_rddm_prepare(struct mhi_controller *mhi_cntrl,
+int mhi_rddm_prepare(struct mhi_controller *mhi_cntrl,
 		      struct image_info *img_info);
 void mhi_fw_load_handler(struct mhi_controller *mhi_cntrl);
 int mhi_prepare_channel(struct mhi_controller *mhi_cntrl,
diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index c01ec2f..902d854 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -66,19 +66,22 @@ void mhi_write_reg(struct mhi_controller *mhi_cntrl, void __iomem *base,
 	mhi_cntrl->write_reg(mhi_cntrl, base + offset, val);
 }
 
-void mhi_write_reg_field(struct mhi_controller *mhi_cntrl, void __iomem *base,
-			 u32 offset, u32 mask, u32 shift, u32 val)
+int __must_check mhi_write_reg_field(struct mhi_controller *mhi_cntrl,
+				     void __iomem *base, u32 offset,
+				     u32 mask, u32 shift, u32 val)
 {
 	int ret;
 	u32 tmp;
 
 	ret = mhi_read_reg(mhi_cntrl, base, offset, &tmp);
 	if (ret)
-		return;
+		return ret;
 
 	tmp &= ~mask;
 	tmp |= (val << shift);
 	mhi_write_reg(mhi_cntrl, base, offset, tmp);
+
+	return 0;
 }
 
 void mhi_write_db(struct mhi_controller *mhi_cntrl, void __iomem *db_addr,
-- 
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