linux-kernel - [PATCH 2/5] nvmem: sprd: Optimize the block lock operation

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Date:   Mon, 23 Mar 2020 15:00:04 +0000
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     gregkh@...uxfoundation.org
Cc:     linux-kernel@...r.kernel.org, Freeman Liu <freeman.liu@...soc.com>,
        Baolin Wang <baolin.wang7@...il.com>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Subject: [PATCH 2/5] nvmem: sprd: Optimize the block lock operation

From: Freeman Liu <freeman.liu@...soc.com>

We have some cases that will programme the eFuse block partially multiple
times, so we should allow the block to be programmed again if it was
programmed partially. But we should lock the block if the whole block
was programmed. Thus add a condition to validate if we need lock the
block or not.

Moreover we only enable the auto-check function when locking the block.

Signed-off-by: Freeman Liu <freeman.liu@...soc.com>
Signed-off-by: Baolin Wang <baolin.wang7@...il.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
---
 drivers/nvmem/sprd-efuse.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/nvmem/sprd-efuse.c b/drivers/nvmem/sprd-efuse.c
index 7a189ef52333..43b3f6ef8c20 100644
--- a/drivers/nvmem/sprd-efuse.c
+++ b/drivers/nvmem/sprd-efuse.c
@@ -217,12 +217,14 @@ static int sprd_efuse_raw_prog(struct sprd_efuse *efuse, u32 blk, bool doub,
 	 * Enable the auto-check function to validate if the programming is
 	 * successful.
 	 */
-	sprd_efuse_set_auto_check(efuse, true);
+	if (lock)
+		sprd_efuse_set_auto_check(efuse, true);
 
 	writel(*data, efuse->base + SPRD_EFUSE_MEM(blk));
 
 	/* Disable auto-check and data double after programming */
-	sprd_efuse_set_auto_check(efuse, false);
+	if (lock)
+		sprd_efuse_set_auto_check(efuse, false);
 	sprd_efuse_set_data_double(efuse, false);
 
 	/*
@@ -237,7 +239,7 @@ static int sprd_efuse_raw_prog(struct sprd_efuse *efuse, u32 blk, bool doub,
 		writel(SPRD_EFUSE_ERR_CLR_MASK,
 		       efuse->base + SPRD_EFUSE_ERR_CLR);
 		ret = -EBUSY;
-	} else {
+	} else if (lock) {
 		sprd_efuse_set_prog_lock(efuse, lock);
 		writel(0, efuse->base + SPRD_EFUSE_MEM(blk));
 		sprd_efuse_set_prog_lock(efuse, false);
@@ -322,6 +324,7 @@ static int sprd_efuse_read(void *context, u32 offset, void *val, size_t bytes)
 static int sprd_efuse_write(void *context, u32 offset, void *val, size_t bytes)
 {
 	struct sprd_efuse *efuse = context;
+	bool lock;
 	int ret;
 
 	ret = sprd_efuse_lock(efuse);
@@ -332,7 +335,20 @@ static int sprd_efuse_write(void *context, u32 offset, void *val, size_t bytes)
 	if (ret)
 		goto unlock;
 
-	ret = sprd_efuse_raw_prog(efuse, offset, false, false, val);
+	/*
+	 * If the writing bytes are equal with the block width, which means the
+	 * whole block will be programmed. For this case, we should not allow
+	 * this block to be programmed again by locking this block.
+	 *
+	 * If the block was programmed partially, we should allow this block to
+	 * be programmed again.
+	 */
+	if (bytes < SPRD_EFUSE_BLOCK_WIDTH)
+		lock = false;
+	else
+		lock = true;
+
+	ret = sprd_efuse_raw_prog(efuse, offset, false, lock, val);
 
 	clk_disable_unprepare(efuse->clk);
 
-- 
2.21.0