The i3c abstraction excepts u8 buffers, but some controllers have a bus
width of 32-bits and don't support flagging valid bytes, so it is
required to read/write long words and to use memcpy on the remainder of
the number of bytes by 32-bits to not write/read outside the buffer
bounds.

Signed-off-by: Jorge Marques <jorge.marques@analog.com>
---
 include/linux/i3c/master.h | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h
index c67922ece617d6320c0c7e4838c2e7edda8c19f5..11401f2acb42e4d3a60df33b7c794d8a0360cdc2 100644
--- a/include/linux/i3c/master.h
+++ b/include/linux/i3c/master.h
@@ -674,6 +674,42 @@ i3c_master_get_bus(struct i3c_master_controller *master)
 	return &master->bus;
 }
 
+/**
+ * i3c_master_writesl- Write bytes to long memory region from byte array
+ * @addr: Register to write to
+ * @bytes: Pointer to the data bytes to write
+ * @nbytes: Number of bytes to write
+ */
+static inline void i3c_master_writesl(void __iomem *addr, const u8 *bytes,
+				      int nbytes)
+{
+writesl(addr, bytes, nbytes / 4);
+	if (nbytes & 3) {
+		u32 tmp = 0;
+
+		memcpy(&tmp, bytes + (nbytes & ~3), nbytes & 3);
+		writel(tmp, addr);
+	}
+}
+
+/**
+ * i3c_master_readsl - Read bytes from long memory region to byte array
+ * @addr: Register to read from
+ * @bytes: Pointer to the buffer to store read bytes
+ * @nbytes: Number of bytes to read
+ */
+static inline void i3c_master_readsl(const void __iomem *addr, u8 *bytes,
+				     int nbytes)
+{
+readsl(addr, bytes, nbytes / 4);
+	if (nbytes & 3) {
+		u32 tmp;
+
+		tmp = readl(addr);
+		memcpy(bytes + (nbytes & ~3), &tmp, nbytes & 3);
+	}
+}
+
 struct i3c_generic_ibi_pool;
 
 struct i3c_generic_ibi_pool *

-- 
2.49.0

On Fri, Jun 20, 2025 at 06:54:59PM +0200, Jorge Marques wrote:
> The i3c abstraction excepts u8 buffers, but some controllers have a bus
> width of 32-bits and don't support flagging valid bytes, so it is
> required to read/write long words and to use memcpy on the remainder of
> the number of bytes by 32-bits to not write/read outside the buffer
> bounds.
> 
> Signed-off-by: Jorge Marques <jorge.marques@analog.com>

Suggested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

> + * i3c_master_writesl- Write bytes to long memory region from byte array

Frank proposed the name 'i3c_writel_fifo' which I like a tad better.
Opinions?

On Fri, Jun 20, 2025 at 11:15:09PM +0200, Wolfram Sang wrote:
> On Fri, Jun 20, 2025 at 06:54:59PM +0200, Jorge Marques wrote:
> > The i3c abstraction excepts u8 buffers, but some controllers have a bus
> > width of 32-bits and don't support flagging valid bytes, so it is
> > required to read/write long words and to use memcpy on the remainder of
> > the number of bytes by 32-bits to not write/read outside the buffer
> > bounds.
> > 
> > Signed-off-by: Jorge Marques <jorge.marques@analog.com>
> 
> Suggested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> 
> > + * i3c_master_writesl- Write bytes to long memory region from byte array
> 
Hi Wolfram,
> Frank proposed the name 'i3c_writel_fifo' which I like a tad better.
> Opinions?
>
I don't oppose the change and I'll rename, as well moving the method to
internals.h

  i3c_master_writesl -> i3c_writel_fifo
  i3c_master_readsl -> i3c_readl_fifo

Best Regards,
Jorge

On Fri, Jun 20, 2025 at 06:54:59PM +0200, Jorge Marques wrote:
> The i3c abstraction excepts u8 buffers, but some controllers have a bus
> width of 32-bits and don't support flagging valid bytes, so it is
> required to read/write long words and to use memcpy on the remainder of
> the number of bytes by 32-bits to not write/read outside the buffer
> bounds.
>
> Signed-off-by: Jorge Marques <jorge.marques@analog.com>
> ---
>  include/linux/i3c/master.h | 36 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
>
> diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h
> index c67922ece617d6320c0c7e4838c2e7edda8c19f5..11401f2acb42e4d3a60df33b7c794d8a0360cdc2 100644
> --- a/include/linux/i3c/master.h
> +++ b/include/linux/i3c/master.h

suggest move to drivers/i3c/internals.h becaue only master drivers use it.

> @@ -674,6 +674,42 @@ i3c_master_get_bus(struct i3c_master_controller *master)
>  	return &master->bus;
>  }
>
> +/**
> + * i3c_master_writesl- Write bytes to long memory region from byte array
> + * @addr: Register to write to
> + * @bytes: Pointer to the data bytes to write
> + * @nbytes: Number of bytes to write
> + */
> +static inline void i3c_master_writesl(void __iomem *addr, const u8 *bytes,
> +				      int nbytes)

const void *bytes

> +{
> +writesl(addr, bytes, nbytes / 4);

fix indention

Frank

> +	if (nbytes & 3) {
> +		u32 tmp = 0;
> +
> +		memcpy(&tmp, bytes + (nbytes & ~3), nbytes & 3);
> +		writel(tmp, addr);
> +	}
> +}
> +
> +/**
> + * i3c_master_readsl - Read bytes from long memory region to byte array
> + * @addr: Register to read from
> + * @bytes: Pointer to the buffer to store read bytes
> + * @nbytes: Number of bytes to read
> + */
> +static inline void i3c_master_readsl(const void __iomem *addr, u8 *bytes,
> +				     int nbytes)
> +{
> +readsl(addr, bytes, nbytes / 4);
> +	if (nbytes & 3) {
> +		u32 tmp;
> +
> +		tmp = readl(addr);
> +		memcpy(bytes + (nbytes & ~3), &tmp, nbytes & 3);
> +	}
> +}
> +
>  struct i3c_generic_ibi_pool;
>
>  struct i3c_generic_ibi_pool *
>
> --
> 2.49.0
>
>

On Fri, Jun 20, 2025 at 02:41:12PM -0400, Frank Li wrote:
> On Fri, Jun 20, 2025 at 06:54:59PM +0200, Jorge Marques wrote:
> > The i3c abstraction excepts u8 buffers, but some controllers have a bus
> > width of 32-bits and don't support flagging valid bytes, so it is
> > required to read/write long words and to use memcpy on the remainder of
> > the number of bytes by 32-bits to not write/read outside the buffer
> > bounds.
> >
> > Signed-off-by: Jorge Marques <jorge.marques@analog.com>
> > ---
> >  include/linux/i3c/master.h | 36 ++++++++++++++++++++++++++++++++++++
> >  1 file changed, 36 insertions(+)
> >
> > diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h
> > index c67922ece617d6320c0c7e4838c2e7edda8c19f5..11401f2acb42e4d3a60df33b7c794d8a0360cdc2 100644
> > --- a/include/linux/i3c/master.h
> > +++ b/include/linux/i3c/master.h
> 
> suggest move to drivers/i3c/internals.h becaue only master drivers use it.
> 
Hi Frank,
Ok, also renaming to i3c_writel_fifo() and i3c_readl_fifo() as well
reworking the commit messages.
> > @@ -674,6 +674,42 @@ i3c_master_get_bus(struct i3c_master_controller *master)
> >  	return &master->bus;
> >  }
> >
> > +/**
> > + * i3c_master_writesl- Write bytes to long memory region from byte array
> > + * @addr: Register to write to
> > + * @bytes: Pointer to the data bytes to write
> > + * @nbytes: Number of bytes to write
> > + */
> > +static inline void i3c_master_writesl(void __iomem *addr, const u8 *bytes,
> > +				      int nbytes)
> 
> const void *bytes
> 
Ack.

> > +{
> > +writesl(addr, bytes, nbytes / 4);
> 
> fix indention
> 
> Frank
> 
Ack.

Best regards,
Jorge
> > +	if (nbytes & 3) {
> > +		u32 tmp = 0;
> > +
> > +		memcpy(&tmp, bytes + (nbytes & ~3), nbytes & 3);
> > +		writel(tmp, addr);
> > +	}
> > +}
> > +
> > +/**
> > + * i3c_master_readsl - Read bytes from long memory region to byte array
> > + * @addr: Register to read from
> > + * @bytes: Pointer to the buffer to store read bytes
> > + * @nbytes: Number of bytes to read
> > + */
> > +static inline void i3c_master_readsl(const void __iomem *addr, u8 *bytes,
> > +				     int nbytes)
> > +{
> > +readsl(addr, bytes, nbytes / 4);
> > +	if (nbytes & 3) {
> > +		u32 tmp;
> > +
> > +		tmp = readl(addr);
> > +		memcpy(bytes + (nbytes & ~3), &tmp, nbytes & 3);
> > +	}
> > +}
> > +
> >  struct i3c_generic_ibi_pool;
> >
> >  struct i3c_generic_ibi_pool *
> >
> > --
> > 2.49.0
> >
> >