2020-10-22 08:56:26

by Peng Fan

Subject: [PATCH] nvmem: imx-ocotp: add support for the unaliged word count

From: Peng Fan <[email protected]>

When offset is not 4 bytes aligned, directly shift righty by 2 bits
will cause reading out wrong data. Since imx ocotp only supports
4 bytes reading once, we need handle offset is not 4 bytes aligned
and enlarge the bytes to 4 bytes aligned. After reading finished,
copy the needed data from buffer to caller and free buffer.

Signed-off-by: Peng Fan <[email protected]>
---
drivers/nvmem/imx-ocotp.c | 30 ++++++++++++++++++++++++------
1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/drivers/nvmem/imx-ocotp.c b/drivers/nvmem/imx-ocotp.c
index 7a1ebd6fd08b..08f41328cc71 100644
--- a/drivers/nvmem/imx-ocotp.c
+++ b/drivers/nvmem/imx-ocotp.c
@@ -4,6 +4,8 @@
*
* Copyright (c) 2015 Pengutronix, Philipp Zabel <[email protected]>
*
+ * Copyright 2019 NXP
+ *
* Based on the barebox ocotp driver,
* Copyright (c) 2010 Baruch Siach <[email protected]>,
* Orex Computed Radiography
@@ -158,22 +160,30 @@ static int imx_ocotp_read(void *context, unsigned int offset,
{
struct ocotp_priv *priv = context;
unsigned int count;
- u32 *buf = val;
+ u8 *buf, *p;
int i, ret;
- u32 index;
+ u32 index, num_bytes;

index = offset >> 2;
- count = bytes >> 2;
+ num_bytes = round_up((offset % 4) + bytes, 4);
+ count = num_bytes >> 2;

if (count > (priv->params->nregs - index))
count = priv->params->nregs - index;

+ p = kzalloc(num_bytes, GFP_KERNEL);
+ if (!p)
+ return -ENOMEM;
+
mutex_lock(&ocotp_mutex);

+ buf = p;
+
ret = clk_prepare_enable(priv->clk);
if (ret < 0) {
mutex_unlock(&ocotp_mutex);
dev_err(priv->dev, "failed to prepare/enable ocotp clk\n");
+ kfree(p);
return ret;
}

@@ -184,7 +194,7 @@ static int imx_ocotp_read(void *context, unsigned int offset,
}

for (i = index; i < (index + count); i++) {
- *buf++ = readl(priv->base + IMX_OCOTP_OFFSET_B0W0 +
+ *(u32 *)buf = readl(priv->base + IMX_OCOTP_OFFSET_B0W0 +
i * IMX_OCOTP_OFFSET_PER_WORD);

/* 47.3.1.2
@@ -193,13 +203,21 @@ static int imx_ocotp_read(void *context, unsigned int offset,
* software before any new write, read or reload access can be
* issued
*/
- if (*(buf - 1) == IMX_OCOTP_READ_LOCKED_VAL)
+ if (*((u32 *)buf) == IMX_OCOTP_READ_LOCKED_VAL)
imx_ocotp_clr_err_if_set(priv);
+
+ buf += 4;
}

+ index = offset % 4;
+ memcpy(val, &p[index], bytes);
+
read_end:
clk_disable_unprepare(priv->clk);
mutex_unlock(&ocotp_mutex);
+
+ kfree(p);
+
return ret;
}

@@ -447,7 +465,7 @@ static struct nvmem_config imx_ocotp_nvmem_config = {
.name = "imx-ocotp",
.read_only = false,
.word_size = 4,
- .stride = 4,
+ .stride = 1,
.reg_read = imx_ocotp_read,
.reg_write = imx_ocotp_write,
};
--
2.28.0

2020-11-24 10:56:06

by Srinivas Kandagatla

Subject: Re: [PATCH] nvmem: imx-ocotp: add support for the unaliged word count

On 22/10/2020 08:44, [email protected] wrote:
> From: Peng Fan <[email protected]>
>
> When offset is not 4 bytes aligned, directly shift righty by 2 bits
> will cause reading out wrong data. Since imx ocotp only supports
> 4 bytes reading once, we need handle offset is not 4 bytes aligned
> and enlarge the bytes to 4 bytes aligned. After reading finished,
> copy the needed data from buffer to caller and free buffer.
>
> Signed-off-by: Peng Fan <[email protected]>

Applied thanks,

srini