Introduce the helper function pci_epf_align_addr() to adjust addresses
according to PCI BAR alignment requirements, converting addresses into base
and offset values.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
change from v6 to v7
- new patch
---
 drivers/pci/endpoint/pci-epf-core.c | 39 +++++++++++++++++++++++++++++++++++++
 include/linux/pci-epf.h             | 13 +++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c
index 8fa2797d4169a..a3f172cc786e9 100644
--- a/drivers/pci/endpoint/pci-epf-core.c
+++ b/drivers/pci/endpoint/pci-epf-core.c
@@ -464,6 +464,45 @@ struct pci_epf *pci_epf_create(const char *name)
 }
 EXPORT_SYMBOL_GPL(pci_epf_create);
 
+/**
+ * pci_epf_align_addr() - Get base address and offset that match bar's
+ *			  alignment requirement
+ * @epf: the EPF device
+ * @addr: the address of the memory
+ * @bar: the BAR number corresponding to map addr
+ * @base: return base address, which match BAR's alignment requirement, nothing
+ *	  return if NULL
+ * @off: return offset, nothing return if NULL
+ *
+ * Helper function to convert input 'addr' to base and offset, which match
+ * BAR's alignment requirement.
+ */
+int pci_epf_align_addr(struct pci_epf *epf, enum pci_barno bar, u64 addr, u64 *base, size_t *off)
+{
+	const struct pci_epc_features *epc_features;
+	u64 align;
+
+	epc_features = pci_epc_get_features(epf->epc, epf->func_no, epf->vfunc_no);
+	if (!epc_features) {
+		dev_err(&epf->dev, "epc_features not implemented\n");
+		return -EOPNOTSUPP;
+	}
+
+	align = epc_features->align;
+	align = align ? align : 128;
+	if (epc_features->bar[bar].type == BAR_FIXED)
+		align = max(epc_features->bar[bar].fixed_size, align);
+
+	if (base)
+		*base = round_down(addr, align);
+
+	if (off)
+		*off = addr & (align - 1);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pci_epf_align_addr);
+
 static void pci_epf_dev_release(struct device *dev)
 {
 	struct pci_epf *epf = to_pci_epf(dev);
diff --git a/include/linux/pci-epf.h b/include/linux/pci-epf.h
index 5374e6515ffa0..20f4f31ba9b36 100644
--- a/include/linux/pci-epf.h
+++ b/include/linux/pci-epf.h
@@ -238,6 +238,19 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar,
 			  enum pci_epc_interface_type type);
 void pci_epf_free_space(struct pci_epf *epf, void *addr, enum pci_barno bar,
 			enum pci_epc_interface_type type);
+
+int pci_epf_align_addr(struct pci_epf *epf, enum pci_barno bar, u64 addr, u64 *base, size_t *off);
+static inline int pci_epf_align_addr_lo_hi(struct pci_epf *epf, enum pci_barno bar,
+					   u32 low, u32 high, u64 *base, size_t *off)
+{
+	u64 addr = high;
+
+	addr <<= 32;
+	addr |= low;
+
+	return pci_epf_align_addr(epf, bar, addr, base, off);
+}
+
 int pci_epf_bind(struct pci_epf *epf);
 void pci_epf_unbind(struct pci_epf *epf);
 int pci_epf_add_vepf(struct pci_epf *epf_pf, struct pci_epf *epf_vf);

-- 
2.34.1

On Thu, Nov 14, 2024 at 05:52:39PM -0500, Frank Li wrote:
> Introduce the helper function pci_epf_align_addr() to adjust addresses
> according to PCI BAR alignment requirements, converting addresses into base
> and offset values.
> 
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
> change from v6 to v7
> - new patch
> ---
>  drivers/pci/endpoint/pci-epf-core.c | 39 +++++++++++++++++++++++++++++++++++++
>  include/linux/pci-epf.h             | 13 +++++++++++++
>  2 files changed, 52 insertions(+)
> 
> diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c
> index 8fa2797d4169a..a3f172cc786e9 100644
> --- a/drivers/pci/endpoint/pci-epf-core.c
> +++ b/drivers/pci/endpoint/pci-epf-core.c
> @@ -464,6 +464,45 @@ struct pci_epf *pci_epf_create(const char *name)
>  }
>  EXPORT_SYMBOL_GPL(pci_epf_create);
>  
> +/**
> + * pci_epf_align_addr() - Get base address and offset that match bar's
> + *			  alignment requirement
> + * @epf: the EPF device
> + * @addr: the address of the memory
> + * @bar: the BAR number corresponding to map addr
> + * @base: return base address, which match BAR's alignment requirement, nothing
> + *	  return if NULL
> + * @off: return offset, nothing return if NULL
> + *
> + * Helper function to convert input 'addr' to base and offset, which match
> + * BAR's alignment requirement.

Should we perhaps also mention that this function is not needed in the
"normal case" ? (i.e. pci_epf_alloc_space() + pci_epc_set_bar())


Kind regards,
Niklas

On Thu, Nov 14, 2024 at 05:52:39PM -0500, Frank Li wrote:
> Introduce the helper function pci_epf_align_addr() to adjust addresses
> according to PCI BAR alignment requirements, converting addresses into base
> and offset values.
> 
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
> change from v6 to v7
> - new patch
> ---
>  drivers/pci/endpoint/pci-epf-core.c | 39 +++++++++++++++++++++++++++++++++++++
>  include/linux/pci-epf.h             | 13 +++++++++++++
>  2 files changed, 52 insertions(+)
> 
> diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c
> index 8fa2797d4169a..a3f172cc786e9 100644
> --- a/drivers/pci/endpoint/pci-epf-core.c
> +++ b/drivers/pci/endpoint/pci-epf-core.c
> @@ -464,6 +464,45 @@ struct pci_epf *pci_epf_create(const char *name)
>  }
>  EXPORT_SYMBOL_GPL(pci_epf_create);
>  
> +/**
> + * pci_epf_align_addr() - Get base address and offset that match bar's
> + *			  alignment requirement
> + * @epf: the EPF device
> + * @addr: the address of the memory
> + * @bar: the BAR number corresponding to map addr
> + * @base: return base address, which match BAR's alignment requirement, nothing
> + *	  return if NULL
> + * @off: return offset, nothing return if NULL
> + *
> + * Helper function to convert input 'addr' to base and offset, which match
> + * BAR's alignment requirement.
> + */
> +int pci_epf_align_addr(struct pci_epf *epf, enum pci_barno bar, u64 addr, u64 *base, size_t *off)

Nit: perhaps rename this function to:
pci_epf_align_ib_addr()
or
pci_epf_align_inbound_addr()

to more clearly not confuse this with:
if (epc->ops->align_addr)
.align_addr()
(Ideally those functions should have been named align_ob_addr(),
or align_outbound_addr())


> +{
> +	const struct pci_epc_features *epc_features;
> +	u64 align;
> +
> +	epc_features = pci_epc_get_features(epf->epc, epf->func_no, epf->vfunc_no);
> +	if (!epc_features) {
> +		dev_err(&epf->dev, "epc_features not implemented\n");
> +		return -EOPNOTSUPP;
> +	}
> +
> +	align = epc_features->align;
> +	align = align ? align : 128;
> +	if (epc_features->bar[bar].type == BAR_FIXED)
> +		align = max(epc_features->bar[bar].fixed_size, align);
> +
> +	if (base)
> +		*base = round_down(addr, align);
> +
> +	if (off)
> +		*off = addr & (align - 1);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(pci_epf_align_addr);
> +
>  static void pci_epf_dev_release(struct device *dev)
>  {
>  	struct pci_epf *epf = to_pci_epf(dev);
> diff --git a/include/linux/pci-epf.h b/include/linux/pci-epf.h
> index 5374e6515ffa0..20f4f31ba9b36 100644
> --- a/include/linux/pci-epf.h
> +++ b/include/linux/pci-epf.h
> @@ -238,6 +238,19 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar,
>  			  enum pci_epc_interface_type type);
>  void pci_epf_free_space(struct pci_epf *epf, void *addr, enum pci_barno bar,
>  			enum pci_epc_interface_type type);
> +
> +int pci_epf_align_addr(struct pci_epf *epf, enum pci_barno bar, u64 addr, u64 *base, size_t *off);
> +static inline int pci_epf_align_addr_lo_hi(struct pci_epf *epf, enum pci_barno bar,
> +					   u32 low, u32 high, u64 *base, size_t *off)
> +{
> +	u64 addr = high;
> +
> +	addr <<= 32;
> +	addr |= low;
> +
> +	return pci_epf_align_addr(epf, bar, addr, base, off);
> +}

I'm not sure if this function deserves to live :)
Can't the caller just do this before calling pci_epf_align_addr() ?


Kind regards,
Niklas

On Fri, Nov 15, 2024 at 10:53:07AM +0100, Niklas Cassel wrote:
> On Thu, Nov 14, 2024 at 05:52:39PM -0500, Frank Li wrote:
> > Introduce the helper function pci_epf_align_addr() to adjust addresses
> > according to PCI BAR alignment requirements, converting addresses into base
> > and offset values.
> >
> > Signed-off-by: Frank Li <Frank.Li@nxp.com>
> > ---
> > change from v6 to v7
> > - new patch
> > ---
> >  drivers/pci/endpoint/pci-epf-core.c | 39 +++++++++++++++++++++++++++++++++++++
> >  include/linux/pci-epf.h             | 13 +++++++++++++
> >  2 files changed, 52 insertions(+)
> >
> > diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c
> > index 8fa2797d4169a..a3f172cc786e9 100644
> > --- a/drivers/pci/endpoint/pci-epf-core.c
> > +++ b/drivers/pci/endpoint/pci-epf-core.c
> > @@ -464,6 +464,45 @@ struct pci_epf *pci_epf_create(const char *name)
> >  }
> >  EXPORT_SYMBOL_GPL(pci_epf_create);
> >
> > +/**
> > + * pci_epf_align_addr() - Get base address and offset that match bar's
> > + *			  alignment requirement
> > + * @epf: the EPF device
> > + * @addr: the address of the memory
> > + * @bar: the BAR number corresponding to map addr
> > + * @base: return base address, which match BAR's alignment requirement, nothing
> > + *	  return if NULL
> > + * @off: return offset, nothing return if NULL
> > + *
> > + * Helper function to convert input 'addr' to base and offset, which match
> > + * BAR's alignment requirement.
> > + */
> > +int pci_epf_align_addr(struct pci_epf *epf, enum pci_barno bar, u64 addr, u64 *base, size_t *off)
>
> Nit: perhaps rename this function to:
> pci_epf_align_ib_addr()
> or
> pci_epf_align_inbound_addr()
>
> to more clearly not confuse this with:
> if (epc->ops->align_addr)
> .align_addr()
> (Ideally those functions should have been named align_ob_addr(),
> or align_outbound_addr())
>
>
> > +{
> > +	const struct pci_epc_features *epc_features;
> > +	u64 align;
> > +
> > +	epc_features = pci_epc_get_features(epf->epc, epf->func_no, epf->vfunc_no);
> > +	if (!epc_features) {
> > +		dev_err(&epf->dev, "epc_features not implemented\n");
> > +		return -EOPNOTSUPP;
> > +	}
> > +
> > +	align = epc_features->align;
> > +	align = align ? align : 128;
> > +	if (epc_features->bar[bar].type == BAR_FIXED)
> > +		align = max(epc_features->bar[bar].fixed_size, align);
> > +
> > +	if (base)
> > +		*base = round_down(addr, align);
> > +
> > +	if (off)
> > +		*off = addr & (align - 1);
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(pci_epf_align_addr);
> > +
> >  static void pci_epf_dev_release(struct device *dev)
> >  {
> >  	struct pci_epf *epf = to_pci_epf(dev);
> > diff --git a/include/linux/pci-epf.h b/include/linux/pci-epf.h
> > index 5374e6515ffa0..20f4f31ba9b36 100644
> > --- a/include/linux/pci-epf.h
> > +++ b/include/linux/pci-epf.h
> > @@ -238,6 +238,19 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar,
> >  			  enum pci_epc_interface_type type);
> >  void pci_epf_free_space(struct pci_epf *epf, void *addr, enum pci_barno bar,
> >  			enum pci_epc_interface_type type);
> > +
> > +int pci_epf_align_addr(struct pci_epf *epf, enum pci_barno bar, u64 addr, u64 *base, size_t *off);
> > +static inline int pci_epf_align_addr_lo_hi(struct pci_epf *epf, enum pci_barno bar,
> > +					   u32 low, u32 high, u64 *base, size_t *off)
> > +{
> > +	u64 addr = high;
> > +
> > +	addr <<= 32;
> > +	addr |= low;
> > +
> > +	return pci_epf_align_addr(epf, bar, addr, base, off);
> > +}
>
> I'm not sure if this function deserves to live :)
> Can't the caller just do this before calling pci_epf_align_addr() ?

Ideally, kernel should have macro to combine 32bit macro to a 64bit, but
I have not found it.

It is quite easy to make error or warning by simple
(high << 32 | low)

It needs ((u64) high << 32 | low) at least. I just want to avoid everyone
to struggle simple issue.

And msi_msg use lo and hi. pci_function_test actually just demostrate how
to use doorbell. if other function driver use doorbell in future, avoid
"(u64) high << 32 | low" copy to everywhere.

Maybe like upper_32_bits(), add global helper macro

#define low32_high32_to_64bit(l, h) ((u64)(h) << 32 | low)

Frank
>
>
> Kind regards,
> Niklas

On Fri, Nov 15, 2024 at 11:43:22AM -0500, Frank Li wrote:
> On Fri, Nov 15, 2024 at 10:53:07AM +0100, Niklas Cassel wrote:
> > On Thu, Nov 14, 2024 at 05:52:39PM -0500, Frank Li wrote:
> > > +static inline int pci_epf_align_addr_lo_hi(struct pci_epf *epf, enum pci_barno bar,
> > > +					   u32 low, u32 high, u64 *base, size_t *off)
> > > +{
> > > +	u64 addr = high;
> > > +
> > > +	addr <<= 32;
> > > +	addr |= low;
> > > +
> > > +	return pci_epf_align_addr(epf, bar, addr, base, off);
> > > +}
> >
> > I'm not sure if this function deserves to live :)
> > Can't the caller just do this before calling pci_epf_align_addr() ?
> 
> Ideally, kernel should have macro to combine 32bit macro to a 64bit, but
> I have not found it.
> 
> It is quite easy to make error or warning by simple
> (high << 32 | low)
> 
> It needs ((u64) high << 32 | low) at least. I just want to avoid everyone
> to struggle simple issue.
> 
> And msi_msg use lo and hi. pci_function_test actually just demostrate how
> to use doorbell. if other function driver use doorbell in future, avoid
> "(u64) high << 32 | low" copy to everywhere.

Keeping the helper is fine with me, but it probably should be renamed
to include _ib_ or _inbound_ in the function name, similar to the comment
for pci_epf_align_addr().


Kind regards,
Niklas