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 *
--
2.49.0On 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
> >
> >
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