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[V1,0/4] nvmem: introduce "reverse-data" property

Message ID 20210810073510.18218-1-qiangqing.zhang@nxp.com
Headers show
Series nvmem: introduce "reverse-data" property | expand

Message

Joakim Zhang Aug. 10, 2021, 7:35 a.m. UTC 
This patch adds "reverse-data" property at nvmem provider to reverse
buffer if nvmem consumer needed.

Please refer to [1] which reverse data at consumer side, but already
rejected by Rob Herring.

[1] https://lkml.org/lkml/2021/4/9/352

Joakim Zhang (4):
  bindings: nvmem: introduce "reverse-data" property
  nvmem: core: introduce "reverse-data" property to reverse buffer
  arm64: dts: imx8m: add "reverse-data" property for MAC ocopt
  arm64: dts: imx8m: remove unused "nvmem_macaddr_swap" property for FEC

 .../devicetree/bindings/nvmem/nvmem.yaml      |  5 ++++
 arch/arm64/boot/dts/freescale/imx8mm.dtsi     |  2 +-
 arch/arm64/boot/dts/freescale/imx8mn.dtsi     |  2 +-
 arch/arm64/boot/dts/freescale/imx8mp.dtsi     |  2 +-
 arch/arm64/boot/dts/freescale/imx8mq.dtsi     |  2 +-
 drivers/nvmem/core.c                          | 30 +++++++++++++++++++
 include/linux/nvmem-provider.h                |  2 ++
 7 files changed, 41 insertions(+), 4 deletions(-)

Comments

Srinivas Kandagatla Aug. 11, 2021, 9:52 a.m. UTC | #1 
On 10/08/2021 08:35, Joakim Zhang wrote:
> This patch intends to introduce "reverse-data" property at nvmem
> provider side to reverse buffer.
> 
> For a case used from Ethernet driver, of_get_mac_address() may call
> of_get_mac_addr_nvmem() to get MAC address from nvmem device. MAC address
> programed in imx-ocopt is MSB first in lowest address, so need reverse

Is all the data stored in imx-ocopt reverse byte order?

or someone decided to change the order for only mac-address?


> data then feedback to nvmem consumer. E.g. MAC address read from
> imx-ocopt is 98:e2:06:9f:04:00, after reversed the data is
> 00:04:9f:06:e2:98.
> 
> Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
> ---
>   drivers/nvmem/core.c           | 30 ++++++++++++++++++++++++++++++
>   include/linux/nvmem-provider.h |  2 ++
>   2 files changed, 32 insertions(+)
> 
> diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> index b3bc30a04ed7..ccc2c5801c8e 100644
> --- a/drivers/nvmem/core.c
> +++ b/drivers/nvmem/core.c
> @@ -55,6 +55,7 @@ struct nvmem_cell {
>   	struct device_node	*np;
>   	struct nvmem_device	*nvmem;
>   	struct list_head	node;
> +	u32			flags;

This flag also needs to go in struct nvmem_cell_info too.

>   };
>   
>   static DEFINE_MUTEX(nvmem_mutex);
> @@ -92,6 +93,26 @@ static int __nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
>   	return -EINVAL;
>   }
>   
> +static int nvmem_buffer_reverse(void *bufaddr, int len)
> +{
> +	u8 *buf = (u8 *)bufaddr;
> +	u8 *temp;
> +	int i;
> +
> +	temp = kzalloc(len, GFP_KERNEL);
> +	if (!temp)
> +		return -ENOMEM;
> +
> +	memcpy(temp, buf, len);
> +
> +	for (i = 0; i < len; i++)
> +		buf[i] = temp[len - i - 1];
> +

You could possibly simplify this.

static void nvmem_buffer_reverse(u8 *buf, int len)
{
	int i;

	for (i = 0; i < len/2; i++)
		swap(buf[i], buf[len - i - 1]);
}

> +	kfree(temp);
> +
> +	return 0;
> +}
> +
>   static int nvmem_access_with_keepouts(struct nvmem_device *nvmem,
>   				      unsigned int offset, void *val,
>   				      size_t bytes, int write)
> @@ -705,6 +726,9 @@ static int nvmem_add_cells_from_of(struct nvmem_device *nvmem)
>   		cell->bytes = be32_to_cpup(addr);
>   		cell->name = kasprintf(GFP_KERNEL, "%pOFn", child);
>   
> +		if (of_property_read_bool(child, "reverse-data"))
> +			cell->flags |= NVMEM_FLAGS_REVERSE_DATA;
> +
>   		addr = of_get_property(child, "bits", &len);
>   		if (addr && len == (2 * sizeof(u32))) {
>   			cell->bit_offset = be32_to_cpup(addr++);
> @@ -1398,6 +1422,12 @@ static int __nvmem_cell_read(struct nvmem_device *nvmem,
>   	if (cell->bit_offset || cell->nbits)
>   		nvmem_shift_read_buffer_in_place(cell, buf);
>   
> +	if (cell->flags & NVMEM_FLAGS_REVERSE_DATA) {
> +		rc = nvmem_buffer_reverse(buf, cell->bytes);
> +		if (rc < 0)
> +			return rc;
> +	}
> +
>   	if (len)
>   		*len = cell->bytes;
>   
> diff --git a/include/linux/nvmem-provider.h b/include/linux/nvmem-provider.h
> index 104505e9028f..364ac2a61b11 100644
> --- a/include/linux/nvmem-provider.h
> +++ b/include/linux/nvmem-provider.h
> @@ -31,6 +31,8 @@ enum nvmem_type {
>   #define NVMEM_DEVID_NONE	(-1)
>   #define NVMEM_DEVID_AUTO	(-2)
>   
> +#define NVMEM_FLAGS_REVERSE_DATA	BIT(0)

Maybe NVMEM_FLAGS_REVERSE_BYTE_ORDER and some kerneldoc would help new 
users.

--srini
> +
>   /**
>    * struct nvmem_keepout - NVMEM register keepout range.
>    *
>
Joakim Zhang Aug. 11, 2021, 10:16 a.m. UTC | #2 
> -----Original Message-----
> From: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
> Sent: 2021年8月11日 17:52
> To: Joakim Zhang <qiangqing.zhang@nxp.com>; robh+dt@kernel.org;
> shawnguo@kernel.org
> Cc: kernel@pengutronix.de; dl-linux-imx <linux-imx@nxp.com>;
> devicetree@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH V1 2/4] nvmem: core: introduce "reverse-data" property
> to reverse buffer
> 
> 
> 
> On 10/08/2021 08:35, Joakim Zhang wrote:
> > This patch intends to introduce "reverse-data" property at nvmem
> > provider side to reverse buffer.
> >
> > For a case used from Ethernet driver, of_get_mac_address() may call
> > of_get_mac_addr_nvmem() to get MAC address from nvmem device. MAC
> > address programed in imx-ocopt is MSB first in lowest address, so need
> > reverse
> 
> Is all the data stored in imx-ocopt reverse byte order?

No, it depends on how users program these data.

> or someone decided to change the order for only mac-address?

No, will not change the order for mac-address, would be consistent.

> 
> > data then feedback to nvmem consumer. E.g. MAC address read from
> > imx-ocopt is 98:e2:06:9f:04:00, after reversed the data is
> > 00:04:9f:06:e2:98.
> >
> > Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
> > ---
> >   drivers/nvmem/core.c           | 30
> ++++++++++++++++++++++++++++++
> >   include/linux/nvmem-provider.h |  2 ++
> >   2 files changed, 32 insertions(+)
> >
> > diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c index
> > b3bc30a04ed7..ccc2c5801c8e 100644
> > --- a/drivers/nvmem/core.c
> > +++ b/drivers/nvmem/core.c
> > @@ -55,6 +55,7 @@ struct nvmem_cell {
> >   	struct device_node	*np;
> >   	struct nvmem_device	*nvmem;
> >   	struct list_head	node;
> > +	u32			flags;
> 
> This flag also needs to go in struct nvmem_cell_info too.

OK.

> >   };
> >
> >   static DEFINE_MUTEX(nvmem_mutex);
> > @@ -92,6 +93,26 @@ static int __nvmem_reg_write(struct nvmem_device
> *nvmem, unsigned int offset,
> >   	return -EINVAL;
> >   }
> >
> > +static int nvmem_buffer_reverse(void *bufaddr, int len) {
> > +	u8 *buf = (u8 *)bufaddr;
> > +	u8 *temp;
> > +	int i;
> > +
> > +	temp = kzalloc(len, GFP_KERNEL);
> > +	if (!temp)
> > +		return -ENOMEM;
> > +
> > +	memcpy(temp, buf, len);
> > +
> > +	for (i = 0; i < len; i++)
> > +		buf[i] = temp[len - i - 1];
> > +
> 
> You could possibly simplify this.
> 
> static void nvmem_buffer_reverse(u8 *buf, int len) {
> 	int i;
> 
> 	for (i = 0; i < len/2; i++)
> 		swap(buf[i], buf[len - i - 1]);
> }

Thanks.

> > +	kfree(temp);
> > +
> > +	return 0;
> > +}
> > +
> >   static int nvmem_access_with_keepouts(struct nvmem_device *nvmem,
> >   				      unsigned int offset, void *val,
> >   				      size_t bytes, int write)
> > @@ -705,6 +726,9 @@ static int nvmem_add_cells_from_of(struct
> nvmem_device *nvmem)
> >   		cell->bytes = be32_to_cpup(addr);
> >   		cell->name = kasprintf(GFP_KERNEL, "%pOFn", child);
> >
> > +		if (of_property_read_bool(child, "reverse-data"))
> > +			cell->flags |= NVMEM_FLAGS_REVERSE_DATA;
> > +
> >   		addr = of_get_property(child, "bits", &len);
> >   		if (addr && len == (2 * sizeof(u32))) {
> >   			cell->bit_offset = be32_to_cpup(addr++); @@ -1398,6
> +1422,12 @@
> > static int __nvmem_cell_read(struct nvmem_device *nvmem,
> >   	if (cell->bit_offset || cell->nbits)
> >   		nvmem_shift_read_buffer_in_place(cell, buf);
> >
> > +	if (cell->flags & NVMEM_FLAGS_REVERSE_DATA) {
> > +		rc = nvmem_buffer_reverse(buf, cell->bytes);
> > +		if (rc < 0)
> > +			return rc;
> > +	}
> > +
> >   	if (len)
> >   		*len = cell->bytes;
> >
> > diff --git a/include/linux/nvmem-provider.h
> > b/include/linux/nvmem-provider.h index 104505e9028f..364ac2a61b11
> > 100644
> > --- a/include/linux/nvmem-provider.h
> > +++ b/include/linux/nvmem-provider.h
> > @@ -31,6 +31,8 @@ enum nvmem_type {
> >   #define NVMEM_DEVID_NONE	(-1)
> >   #define NVMEM_DEVID_AUTO	(-2)
> >
> > +#define NVMEM_FLAGS_REVERSE_DATA	BIT(0)
> 
> Maybe NVMEM_FLAGS_REVERSE_BYTE_ORDER and some kerneldoc would
> help new users.

Yes, will rename it, could you please point me where nvmem kerneldoc there to add new info?

Best Regards,
Joakim Zhang
> --srini
> > +
> >   /**
> >    * struct nvmem_keepout - NVMEM register keepout range.
> >    *
> >