[PATCH v3 0/5] nvmem: qfprom: add Qualcomm SAR2130P support

[PATCH v3 0/5] nvmem: qfprom: add Qualcomm SAR2130P support

[Dmitry Baryshkov]

Qualcomm SAR2130P is one of the platforms which require 4-byte reads
when accessing the QFPROM data. Fix several omission in the NVMEM core,
rework the QFPROM driver to use readl() instead of readb() and finally
add compatible string for the QFPROM as present on the Qualcomm
SAR2130P.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
Changes in v3:
- Reworked the qfprom driver to specify stride and word size (Srinivas)
- Link to v2: https://lore.kernel.org/r/20241027-sar2130p-nvmem-v2-0-743c1271bf2d@linaro.org

Changes in v2:
- Picked up required patch from QCLinux.
- Link to v1: https://lore.kernel.org/r/20241017-sar2130p-nvmem-v1-1-6cc32789afc6@linaro.org

---
Dmitry Baryshkov (5):
      nvmem: core: fix bit offsets of more than one byte
      nvmem: core: verify cell's raw_len
      nvmem: core: update raw_len if the bit reading is required
      nvmem: qfprom: switch to 4-byte aligned reads
      dt-bindings: nvmem: qcom,qfprom: Add SAR2130P compatible

 .../devicetree/bindings/nvmem/qcom,qfprom.yaml     |  1 +
 drivers/nvmem/core.c                               | 36 +++++++++++++++++-----
 drivers/nvmem/qfprom.c                             | 26 ++++++++++++----
 3 files changed, 49 insertions(+), 14 deletions(-)
---
base-commit: f8bde2c106663ee2398a16bf6500f1cc8f5cf64e
change-id: 20241017-sar2130p-nvmem-5f856d99bbb7

Best regards,
-- 
Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

[PATCH v3 1/5] nvmem: core: fix bit offsets of more than one byte

[Dmitry Baryshkov]

If the NVMEM specifies a stride to access data, reading particular cell
might require bit offset that is bigger than one byte. Rework NVMEM core
code to support bit offsets of more than 8 bits.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/nvmem/core.c | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index d6494dfc20a7324bde6415776dcabbb0bfdd334b..c0af43a37195c3869507a203b370615309aeee67 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -834,7 +834,9 @@ static int nvmem_add_cells_from_dt(struct nvmem_device *nvmem, struct device_nod
 		if (addr && len == (2 * sizeof(u32))) {
 			info.bit_offset = be32_to_cpup(addr++);
 			info.nbits = be32_to_cpup(addr);
-			if (info.bit_offset >= BITS_PER_BYTE || info.nbits < 1) {
+			if (info.bit_offset >= BITS_PER_BYTE * info.bytes ||
+			    info.nbits < 1 ||
+			    info.bit_offset + info.nbits >= BITS_PER_BYTE * info.bytes) {
 				dev_err(dev, "nvmem: invalid bits on %pOF\n", child);
 				of_node_put(child);
 				return -EINVAL;
@@ -1627,21 +1629,29 @@ EXPORT_SYMBOL_GPL(nvmem_cell_put);
 static void nvmem_shift_read_buffer_in_place(struct nvmem_cell_entry *cell, void *buf)
 {
 	u8 *p, *b;
-	int i, extra, bit_offset = cell->bit_offset;
+	int i, extra, bytes_offset;
+	int bit_offset = cell->bit_offset;
 
 	p = b = buf;
-	if (bit_offset) {
+
+	bytes_offset = bit_offset / BITS_PER_BYTE;
+	b += bytes_offset;
+	bit_offset %= BITS_PER_BYTE;
+
+	if (bit_offset % BITS_PER_BYTE) {
 		/* First shift */
-		*b++ >>= bit_offset;
+		*p = *b++ >> bit_offset;
 
 		/* setup rest of the bytes if any */
 		for (i = 1; i < cell->bytes; i++) {
 			/* Get bits from next byte and shift them towards msb */
-			*p |= *b << (BITS_PER_BYTE - bit_offset);
+			*p++ |= *b << (BITS_PER_BYTE - bit_offset);
 
-			p = b;
-			*b++ >>= bit_offset;
+			*p = *b++ >> bit_offset;
 		}
+	} else if (p != b) {
+		memmove(p, b, cell->bytes - bytes_offset);
+		p += cell->bytes - 1;
 	} else {
 		/* point to the msb */
 		p += cell->bytes - 1;

-- 
2.39.5

Re: [PATCH v3 1/5] nvmem: core: fix bit offsets of more than one byte

[Akhil P Oommen]

On 1/4/2025 11:49 AM, Dmitry Baryshkov wrote:
> If the NVMEM specifies a stride to access data, reading particular cell
> might require bit offset that is bigger than one byte. Rework NVMEM core
> code to support bit offsets of more than 8 bits.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---
>  drivers/nvmem/core.c | 24 +++++++++++++++++-------
>  1 file changed, 17 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> index d6494dfc20a7324bde6415776dcabbb0bfdd334b..c0af43a37195c3869507a203b370615309aeee67 100644
> --- a/drivers/nvmem/core.c
> +++ b/drivers/nvmem/core.c
> @@ -834,7 +834,9 @@ static int nvmem_add_cells_from_dt(struct nvmem_device *nvmem, struct device_nod
>  		if (addr && len == (2 * sizeof(u32))) {
>  			info.bit_offset = be32_to_cpup(addr++);
>  			info.nbits = be32_to_cpup(addr);
> -			if (info.bit_offset >= BITS_PER_BYTE || info.nbits < 1) {
> +			if (info.bit_offset >= BITS_PER_BYTE * info.bytes ||
> +			    info.nbits < 1 ||
> +			    info.bit_offset + info.nbits >= BITS_PER_BYTE * info.bytes) {

Should it be ">" check instead of ">=" check here?
For eg: bit_offset = 7, nbits = 1 and info.bytes = 1 is valid, isn't it?

-Akhil

>  				dev_err(dev, "nvmem: invalid bits on %pOF\n", child);
>  				of_node_put(child);
>  				return -EINVAL;
> @@ -1627,21 +1629,29 @@ EXPORT_SYMBOL_GPL(nvmem_cell_put);
>  static void nvmem_shift_read_buffer_in_place(struct nvmem_cell_entry *cell, void *buf)
>  {
>  	u8 *p, *b;
> -	int i, extra, bit_offset = cell->bit_offset;
> +	int i, extra, bytes_offset;
> +	int bit_offset = cell->bit_offset;
>  
>  	p = b = buf;
> -	if (bit_offset) {
> +
> +	bytes_offset = bit_offset / BITS_PER_BYTE;
> +	b += bytes_offset;
> +	bit_offset %= BITS_PER_BYTE;
> +
> +	if (bit_offset % BITS_PER_BYTE) {
>  		/* First shift */
> -		*b++ >>= bit_offset;
> +		*p = *b++ >> bit_offset;
>  
>  		/* setup rest of the bytes if any */
>  		for (i = 1; i < cell->bytes; i++) {
>  			/* Get bits from next byte and shift them towards msb */
> -			*p |= *b << (BITS_PER_BYTE - bit_offset);
> +			*p++ |= *b << (BITS_PER_BYTE - bit_offset);
>  
> -			p = b;
> -			*b++ >>= bit_offset;
> +			*p = *b++ >> bit_offset;
>  		}
> +	} else if (p != b) {
> +		memmove(p, b, cell->bytes - bytes_offset);
> +		p += cell->bytes - 1;
>  	} else {
>  		/* point to the msb */
>  		p += cell->bytes - 1;
> 

Re: [PATCH v3 1/5] nvmem: core: fix bit offsets of more than one byte

[Dmitry Baryshkov]

On Thu, Jan 09, 2025 at 03:17:08AM +0530, Akhil P Oommen wrote:
> On 1/4/2025 11:49 AM, Dmitry Baryshkov wrote:
> > If the NVMEM specifies a stride to access data, reading particular cell
> > might require bit offset that is bigger than one byte. Rework NVMEM core
> > code to support bit offsets of more than 8 bits.
> > 
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> > ---
> >  drivers/nvmem/core.c | 24 +++++++++++++++++-------
> >  1 file changed, 17 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> > index d6494dfc20a7324bde6415776dcabbb0bfdd334b..c0af43a37195c3869507a203b370615309aeee67 100644
> > --- a/drivers/nvmem/core.c
> > +++ b/drivers/nvmem/core.c
> > @@ -834,7 +834,9 @@ static int nvmem_add_cells_from_dt(struct nvmem_device *nvmem, struct device_nod
> >  		if (addr && len == (2 * sizeof(u32))) {
> >  			info.bit_offset = be32_to_cpup(addr++);
> >  			info.nbits = be32_to_cpup(addr);
> > -			if (info.bit_offset >= BITS_PER_BYTE || info.nbits < 1) {
> > +			if (info.bit_offset >= BITS_PER_BYTE * info.bytes ||
> > +			    info.nbits < 1 ||
> > +			    info.bit_offset + info.nbits >= BITS_PER_BYTE * info.bytes) {
> 
> Should it be ">" check instead of ">=" check here?
> For eg: bit_offset = 7, nbits = 1 and info.bytes = 1 is valid, isn't it?

Indeed. I'll send v-next.

> 
> -Akhil
> 
> >  				dev_err(dev, "nvmem: invalid bits on %pOF\n", child);
> >  				of_node_put(child);
> >  				return -EINVAL;
> > @@ -1627,21 +1629,29 @@ EXPORT_SYMBOL_GPL(nvmem_cell_put);
> >  static void nvmem_shift_read_buffer_in_place(struct nvmem_cell_entry *cell, void *buf)
> >  {
> >  	u8 *p, *b;
> > -	int i, extra, bit_offset = cell->bit_offset;
> > +	int i, extra, bytes_offset;
> > +	int bit_offset = cell->bit_offset;
> >  
> >  	p = b = buf;
> > -	if (bit_offset) {
> > +
> > +	bytes_offset = bit_offset / BITS_PER_BYTE;
> > +	b += bytes_offset;
> > +	bit_offset %= BITS_PER_BYTE;
> > +
> > +	if (bit_offset % BITS_PER_BYTE) {
> >  		/* First shift */
> > -		*b++ >>= bit_offset;
> > +		*p = *b++ >> bit_offset;
> >  
> >  		/* setup rest of the bytes if any */
> >  		for (i = 1; i < cell->bytes; i++) {
> >  			/* Get bits from next byte and shift them towards msb */
> > -			*p |= *b << (BITS_PER_BYTE - bit_offset);
> > +			*p++ |= *b << (BITS_PER_BYTE - bit_offset);
> >  
> > -			p = b;
> > -			*b++ >>= bit_offset;
> > +			*p = *b++ >> bit_offset;
> >  		}
> > +	} else if (p != b) {
> > +		memmove(p, b, cell->bytes - bytes_offset);
> > +		p += cell->bytes - 1;
> >  	} else {
> >  		/* point to the msb */
> >  		p += cell->bytes - 1;
> > 
> 

-- 
With best wishes
Dmitry

[PATCH v3 2/5] nvmem: core: verify cell's raw_len

[Dmitry Baryshkov]

Check that the NVMEM cell's raw_len is a aligned to word_size. Otherwise
Otherwise drivers might face incomplete read while accessing the last
part of the NVMEM cell.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/nvmem/core.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index c0af43a37195c3869507a203b370615309aeee67..a03a3006bd611ea6e91703cd19c2842bd4f56659 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -602,6 +602,14 @@ static int nvmem_cell_info_to_nvmem_cell_entry_nodup(struct nvmem_device *nvmem,
 		return -EINVAL;
 	}
 
+	if (!IS_ALIGNED(cell->raw_len, nvmem->word_size)) {
+		dev_err(&nvmem->dev,
+			"cell %s raw len %zd unaligned to nvmem word size %d\n",
+			cell->name ?: "<unknown>", cell->raw_len,
+			nvmem->word_size);
+		return -EINVAL;
+	}
+
 	return 0;
 }
 

-- 
2.39.5

[PATCH v3 3/5] nvmem: core: update raw_len if the bit reading is required

[Dmitry Baryshkov]

If NVMEM cell uses bit offset or specifies bit truncation, update
raw_len manually (following the cell->bytes update), ensuring that the
NVMEM access is still word-aligned.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/nvmem/core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index a03a3006bd611ea6e91703cd19c2842bd4f56659..17b320bcbe207aed8a32aa2cc7d8dab9b58c13cf 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -591,9 +591,11 @@ static int nvmem_cell_info_to_nvmem_cell_entry_nodup(struct nvmem_device *nvmem,
 	cell->nbits = info->nbits;
 	cell->np = info->np;
 
-	if (cell->nbits)
+	if (cell->nbits) {
 		cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
 					   BITS_PER_BYTE);
+		cell->raw_len = ALIGN(cell->bytes, nvmem->word_size);
+	}
 
 	if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 		dev_err(&nvmem->dev,

-- 
2.39.5

[PATCH v3 4/5] nvmem: qfprom: switch to 4-byte aligned reads

[Dmitry Baryshkov]

All platforms since Snapdragon 8 Gen1 (SM8450) require using 4-byte
reads to access QFPROM data. While older platforms were more than happy
with 1-byte reads, change the qfprom driver to use 4-byte reads for all
the platforms. Specify stride and word size of 4 bytes. To retain
compatibility with the existing DT and to simplify porting data from
vendor kernels, use fixup_dt_cell_info in order to bump alignment
requirements.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/nvmem/qfprom.c | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/drivers/nvmem/qfprom.c b/drivers/nvmem/qfprom.c
index 116a39e804c70b4a0374f8ea3ac6ba1dd612109d..a872c640b8c5a558da9ea00e3804c904f8987247 100644
--- a/drivers/nvmem/qfprom.c
+++ b/drivers/nvmem/qfprom.c
@@ -321,19 +321,32 @@ static int qfprom_reg_read(void *context,
 			unsigned int reg, void *_val, size_t bytes)
 {
 	struct qfprom_priv *priv = context;
-	u8 *val = _val;
-	int i = 0, words = bytes;
+	u32 *val = _val;
 	void __iomem *base = priv->qfpcorrected;
+	int words = DIV_ROUND_UP(bytes, sizeof(u32));
+	int i;
 
 	if (read_raw_data && priv->qfpraw)
 		base = priv->qfpraw;
 
-	while (words--)
-		*val++ = readb(base + reg + i++);
+	for (i = 0; i < words; i++)
+		*val++ = readl(base + reg + i * sizeof(u32));
 
 	return 0;
 }
 
+/* Align reads to word boundary */
+static void qfprom_fixup_dt_cell_info(struct nvmem_device *nvmem,
+				      struct nvmem_cell_info *cell)
+{
+	unsigned int byte_offset = cell->offset % sizeof(u32);
+
+	cell->bit_offset += byte_offset * BITS_PER_BYTE;
+	cell->offset -= byte_offset;
+	if (byte_offset && !cell->nbits)
+		cell->nbits = cell->bytes * BITS_PER_BYTE;
+}
+
 static void qfprom_runtime_disable(void *data)
 {
 	pm_runtime_disable(data);
@@ -358,10 +371,11 @@ static int qfprom_probe(struct platform_device *pdev)
 	struct nvmem_config econfig = {
 		.name = "qfprom",
 		.add_legacy_fixed_of_cells = true,
-		.stride = 1,
-		.word_size = 1,
+		.stride = 4,
+		.word_size = 4,
 		.id = NVMEM_DEVID_AUTO,
 		.reg_read = qfprom_reg_read,
+		.fixup_dt_cell_info = qfprom_fixup_dt_cell_info,
 	};
 	struct device *dev = &pdev->dev;
 	struct resource *res;

-- 
2.39.5

[PATCH v3 5/5] dt-bindings: nvmem: qcom,qfprom: Add SAR2130P compatible

[Dmitry Baryshkov]

Document compatible for the QFPROM on SAR2130P platform.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 Documentation/devicetree/bindings/nvmem/qcom,qfprom.yaml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/devicetree/bindings/nvmem/qcom,qfprom.yaml b/Documentation/devicetree/bindings/nvmem/qcom,qfprom.yaml
index 80845c722ae46611c722effeaaf014a0caf76e4a..9755b31946bf9d4c1055a993145d06c274b61a37 100644
--- a/Documentation/devicetree/bindings/nvmem/qcom,qfprom.yaml
+++ b/Documentation/devicetree/bindings/nvmem/qcom,qfprom.yaml
@@ -32,6 +32,7 @@ properties:
           - qcom,msm8998-qfprom
           - qcom,qcm2290-qfprom
           - qcom,qcs404-qfprom
+          - qcom,sar2130p-qfprom
           - qcom,sc7180-qfprom
           - qcom,sc7280-qfprom
           - qcom,sc8280xp-qfprom

-- 
2.39.5

Re: [PATCH v3 5/5] dt-bindings: nvmem: qcom,qfprom: Add SAR2130P compatible

[Rob Herring (Arm)]

On Sat, 04 Jan 2025 08:19:16 +0200, Dmitry Baryshkov wrote:
> Document compatible for the QFPROM on SAR2130P platform.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---
>  Documentation/devicetree/bindings/nvmem/qcom,qfprom.yaml | 1 +
>  1 file changed, 1 insertion(+)
> 

Acked-by: Rob Herring (Arm) <robh@kernel.org>