[PATCH v2 0/3] nvmem: stm32: several minor improvements

[PATCH v2 0/3] nvmem: stm32: several minor improvements

[Patrick Delaunay]

Several minor improvement for BSEC driver = nvmem stm32 romem
- move STM32MP15_BSEC_NUM_LOWER in config, to prepare introduction
  of next STM32MP products with more OTP
- add warning when upper OTPs are updated to indicate possible ECC issue
  for second update
- add nvmem type attribute so userspace is able to know how the data is
  stored in OTPs

Changes in v2:
  - Add patch "move STM32MP15_BSEC_NUM_LOWER in config" in the serie,
    solve dependency issue for "priv->lower" in patch "nvmem: stm32:
    add warning when upper OTPs are updated"

Patrick Delaunay (3):
  nvmem: stm32: move STM32MP15_BSEC_NUM_LOWER in config
  nvmem: stm32: add warning when upper OTPs are updated
  nvmem: stm32: add nvmem type attribute

 drivers/nvmem/stm32-romem.c | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

-- 
2.25.1

[PATCH v2 1/3] nvmem: stm32: move STM32MP15_BSEC_NUM_LOWER in config

[Patrick Delaunay]

Support STM32MP15_BSEC_NUM_LOWER in stm32 romem config to prepare
the next SoC in STM32MP family.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
---

Changes in v2:
  - Add patch "move STM32MP15_BSEC_NUM_LOWER in config" in the serie,
    solve dependency issue for "priv->lower" in patch "nvmem: stm32:
    add warning when upper OTPs are updated"

 drivers/nvmem/stm32-romem.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/drivers/nvmem/stm32-romem.c b/drivers/nvmem/stm32-romem.c
index 354be526897f..d93baee01d7b 100644
--- a/drivers/nvmem/stm32-romem.c
+++ b/drivers/nvmem/stm32-romem.c
@@ -22,16 +22,15 @@
 /* shadow registers offest */
 #define STM32MP15_BSEC_DATA0		0x200
 
-/* 32 (x 32-bits) lower shadow registers */
-#define STM32MP15_BSEC_NUM_LOWER	32
-
 struct stm32_romem_cfg {
 	int size;
+	u8 lower;
 };
 
 struct stm32_romem_priv {
 	void __iomem *base;
 	struct nvmem_config cfg;
+	u8 lower;
 };
 
 static int stm32_romem_read(void *context, unsigned int offset, void *buf,
@@ -85,7 +84,7 @@ static int stm32_bsec_read(void *context, unsigned int offset, void *buf,
 	for (i = roffset; (i < roffset + rbytes); i += 4) {
 		u32 otp = i >> 2;
 
-		if (otp < STM32MP15_BSEC_NUM_LOWER) {
+		if (otp < priv->lower) {
 			/* read lower data from shadow registers */
 			val = readl_relaxed(
 				priv->base + STM32MP15_BSEC_DATA0 + i);
@@ -159,6 +158,8 @@ static int stm32_romem_probe(struct platform_device *pdev)
 	priv->cfg.priv = priv;
 	priv->cfg.owner = THIS_MODULE;
 
+	priv->lower = 0;
+
 	cfg = (const struct stm32_romem_cfg *)
 		of_match_device(dev->driver->of_match_table, dev)->data;
 	if (!cfg) {
@@ -167,6 +168,7 @@ static int stm32_romem_probe(struct platform_device *pdev)
 		priv->cfg.reg_read = stm32_romem_read;
 	} else {
 		priv->cfg.size = cfg->size;
+		priv->lower = cfg->lower;
 		priv->cfg.reg_read = stm32_bsec_read;
 		priv->cfg.reg_write = stm32_bsec_write;
 	}
@@ -174,8 +176,17 @@ static int stm32_romem_probe(struct platform_device *pdev)
 	return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &priv->cfg));
 }
 
+/*
+ * STM32MP15 BSEC OTP regions: 4096 OTP bits (with 3072 effective bits)
+ * => 96 x 32-bits data words
+ * - Lower: 1K bits, 2:1 redundancy, incremental bit programming
+ *   => 32 (x 32-bits) lower shadow registers = words 0 to 31
+ * - Upper: 2K bits, ECC protection, word programming only
+ *   => 64 (x 32-bits) = words 32 to 95
+ */
 static const struct stm32_romem_cfg stm32mp15_bsec_cfg = {
-	.size = 384, /* 96 x 32-bits data words */
+	.size = 384,
+	.lower = 32,
 };
 
 static const struct of_device_id stm32_romem_of_match[] = {
-- 
2.25.1

[PATCH v2 2/3] nvmem: stm32: add warning when upper OTPs are updated

[Patrick Delaunay]

As the upper OTPs are ECC protected, they support only one 32 bits word
programming.
For a second modification of this word, these ECC become invalid and
this OTP will be no more accessible, the shadowed value is invalid.

This patch adds a warning to indicate an upper OTP update, because this
operation is dangerous as OTP is not locked by the driver after the first
update to avoid a second update.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
---

(no changes since v1)

 drivers/nvmem/stm32-romem.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/nvmem/stm32-romem.c b/drivers/nvmem/stm32-romem.c
index d93baee01d7b..bb8aa72ba2f9 100644
--- a/drivers/nvmem/stm32-romem.c
+++ b/drivers/nvmem/stm32-romem.c
@@ -132,6 +132,9 @@ static int stm32_bsec_write(void *context, unsigned int offset, void *buf,
 		}
 	}
 
+	if (offset + bytes >= priv->lower * 4)
+		dev_warn(dev, "Update of upper OTPs with ECC protection (word programming, only once)\n");
+
 	return 0;
 }
 
-- 
2.25.1

[PATCH v2 3/3] nvmem: stm32: add nvmem type attribute

[Patrick Delaunay]

Inform NVMEM framework of type attribute for stm32-romem as NVMEM_TYPE_OTP
so userspace is able to know how the data is stored in BSEC.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
---

(no changes since v1)

 drivers/nvmem/stm32-romem.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/nvmem/stm32-romem.c b/drivers/nvmem/stm32-romem.c
index bb8aa72ba2f9..6de565639d5f 100644
--- a/drivers/nvmem/stm32-romem.c
+++ b/drivers/nvmem/stm32-romem.c
@@ -160,6 +160,7 @@ static int stm32_romem_probe(struct platform_device *pdev)
 	priv->cfg.dev = dev;
 	priv->cfg.priv = priv;
 	priv->cfg.owner = THIS_MODULE;
+	priv->cfg.type = NVMEM_TYPE_OTP;
 
 	priv->lower = 0;
 
-- 
2.25.1

Re: [PATCH v2 0/3] nvmem: stm32: several minor improvements

[Srinivas Kandagatla]

On 17/10/2022 16:49, Patrick Delaunay wrote:
> 
> Several minor improvement for BSEC driver = nvmem stm32 romem
> - move STM32MP15_BSEC_NUM_LOWER in config, to prepare introduction
>    of next STM32MP products with more OTP
> - add warning when upper OTPs are updated to indicate possible ECC issue
>    for second update
> - add nvmem type attribute so userspace is able to know how the data is
>    stored in OTPs
> 
> Changes in v2:
>    - Add patch "move STM32MP15_BSEC_NUM_LOWER in config" in the serie,
>      solve dependency issue for "priv->lower" in patch "nvmem: stm32:
>      add warning when upper OTPs are updated"
> 
> Patrick Delaunay (3):
>    nvmem: stm32: move STM32MP15_BSEC_NUM_LOWER in config
>    nvmem: stm32: add warning when upper OTPs are updated
>    nvmem: stm32: add nvmem type attribute
> 
Applied thanks,
--srini

>   drivers/nvmem/stm32-romem.c | 25 ++++++++++++++++++++-----
>   1 file changed, 20 insertions(+), 5 deletions(-)
>