diff mbox series

[v2,06/27] ocxl: Tally up the LPC memory on a link & allow it to be mapped

Message ID 20191203034655.51561-7-alastair@au1.ibm.com
State New, archived
Headers show
Series Add support for OpenCAPI SCM devices | expand

Commit Message

Alastair D'Silva Dec. 3, 2019, 3:46 a.m. UTC
From: Alastair D'Silva <alastair@d-silva.org>

Tally up the LPC memory on an OpenCAPI link & allow it to be mapped

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 drivers/misc/ocxl/core.c          | 10 ++++++
 drivers/misc/ocxl/link.c          | 60 +++++++++++++++++++++++++++++++
 drivers/misc/ocxl/ocxl_internal.h | 33 +++++++++++++++++
 3 files changed, 103 insertions(+)

Comments

Frederic Barrat Jan. 9, 2020, 2:48 p.m. UTC | #1
Le 03/12/2019 à 04:46, Alastair D'Silva a écrit :
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> Tally up the LPC memory on an OpenCAPI link & allow it to be mapped
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---
>   drivers/misc/ocxl/core.c          | 10 ++++++
>   drivers/misc/ocxl/link.c          | 60 +++++++++++++++++++++++++++++++
>   drivers/misc/ocxl/ocxl_internal.h | 33 +++++++++++++++++
>   3 files changed, 103 insertions(+)
> 
> diff --git a/drivers/misc/ocxl/core.c b/drivers/misc/ocxl/core.c
> index b7a09b21ab36..2531c6cf19a0 100644
> --- a/drivers/misc/ocxl/core.c
> +++ b/drivers/misc/ocxl/core.c
> @@ -230,8 +230,18 @@ static int configure_afu(struct ocxl_afu *afu, u8 afu_idx, struct pci_dev *dev)
>   	if (rc)
>   		goto err_free_pasid;
>   
> +	if (afu->config.lpc_mem_size || afu->config.special_purpose_mem_size) {
> +		rc = ocxl_link_add_lpc_mem(afu->fn->link, afu->config.lpc_mem_offset,
> +					   afu->config.lpc_mem_size +
> +					   afu->config.special_purpose_mem_size);
> +		if (rc)
> +			goto err_free_mmio;
> +	}
> +
>   	return 0;
>   
> +err_free_mmio:
> +	unmap_mmio_areas(afu);
>   err_free_pasid:
>   	reclaim_afu_pasid(afu);
>   err_free_actag:
> diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
> index 58d111afd9f6..d8503f0dc6ec 100644
> --- a/drivers/misc/ocxl/link.c
> +++ b/drivers/misc/ocxl/link.c
> @@ -84,6 +84,11 @@ struct ocxl_link {
>   	int dev;
>   	atomic_t irq_available;
>   	struct spa *spa;
> +	struct mutex lpc_mem_lock;
> +	u64 lpc_mem_sz; /* Total amount of LPC memory presented on the link */
> +	u64 lpc_mem;
> +	int lpc_consumers;
> +
>   	void *platform_data;
>   };
>   static struct list_head links_list = LIST_HEAD_INIT(links_list);
> @@ -396,6 +401,8 @@ static int alloc_link(struct pci_dev *dev, int PE_mask, struct ocxl_link **out_l
>   	if (rc)
>   		goto err_spa;
>   
> +	mutex_init(&link->lpc_mem_lock);
> +
>   	/* platform specific hook */
>   	rc = pnv_ocxl_spa_setup(dev, link->spa->spa_mem, PE_mask,
>   				&link->platform_data);
> @@ -711,3 +718,56 @@ void ocxl_link_free_irq(void *link_handle, int hw_irq)
>   	atomic_inc(&link->irq_available);
>   }
>   EXPORT_SYMBOL_GPL(ocxl_link_free_irq);
> +
> +int ocxl_link_add_lpc_mem(void *link_handle, u64 offset, u64 size)
> +{
> +	struct ocxl_link *link = (struct ocxl_link *) link_handle;
> +
> +	// Check for overflow
> +	if (offset > (offset + size))
> +		return -EINVAL;
> +
> +	mutex_lock(&link->lpc_mem_lock);
> +	link->lpc_mem_sz = max(link->lpc_mem_sz, offset + size);
> +
> +	mutex_unlock(&link->lpc_mem_lock);
> +
> +	return 0;
> +}
> +
> +u64 ocxl_link_lpc_map(void *link_handle, struct pci_dev *pdev)
> +{
> +	struct ocxl_link *link = (struct ocxl_link *) link_handle;
> +	u64 lpc_mem;
> +
> +	mutex_lock(&link->lpc_mem_lock);
> +	if (link->lpc_mem) {
> +		lpc_mem = link->lpc_mem;
> +
> +		link->lpc_consumers++;
> +		mutex_unlock(&link->lpc_mem_lock);
> +		return lpc_mem;
> +	}
> +
> +	link->lpc_mem = pnv_ocxl_platform_lpc_setup(pdev, link->lpc_mem_sz);
> +	if (link->lpc_mem)
> +		link->lpc_consumers++;


So if we fail to setup the lpc access in opal, we don't increment 
link->lpc_consumers and we shouldn't call ocxl_link_lpc_release(). Is 
that always true? Risk is to trigger the warning in 
ocxl_link_lpc_release(). So maybe we should check link->lpc_mem first in 
ocxl_link_lpc_release() and exit early if no memory is mapped. It would 
probably avoid hitting the WARN on an error path for example.

    Fred


> +	lpc_mem = link->lpc_mem;
> +	mutex_unlock(&link->lpc_mem_lock);
> +
> +	return lpc_mem;
> +}
> +
> +void ocxl_link_lpc_release(void *link_handle, struct pci_dev *pdev)
> +{
> +	struct ocxl_link *link = (struct ocxl_link *) link_handle;
> +
> +	mutex_lock(&link->lpc_mem_lock);
> +	WARN_ON(--link->lpc_consumers < 0);
> +	if (link->lpc_consumers == 0) {
> +		pnv_ocxl_platform_lpc_release(pdev);
> +		link->lpc_mem = 0;
> +	}
> +
> +	mutex_unlock(&link->lpc_mem_lock);
> +}
> diff --git a/drivers/misc/ocxl/ocxl_internal.h b/drivers/misc/ocxl/ocxl_internal.h
> index 97415afd79f3..20b417e00949 100644
> --- a/drivers/misc/ocxl/ocxl_internal.h
> +++ b/drivers/misc/ocxl/ocxl_internal.h
> @@ -141,4 +141,37 @@ int ocxl_irq_offset_to_id(struct ocxl_context *ctx, u64 offset);
>   u64 ocxl_irq_id_to_offset(struct ocxl_context *ctx, int irq_id);
>   void ocxl_afu_irq_free_all(struct ocxl_context *ctx);
>   
> +/**
> + * ocxl_link_add_lpc_mem() - Increment the amount of memory required by an OpenCAPI link
> + *
> + * @link_handle: The OpenCAPI link handle
> + * @offset: The offset of the memory to add
> + * @size: The amount of memory to increment by
> + *
> + * Return 0 on success, negative on overflow
> + */
> +int ocxl_link_add_lpc_mem(void *link_handle, u64 offset, u64 size);
> +
> +/**
> + * ocxl_link_lpc_map() - Map the LPC memory for an OpenCAPI device
> + *
> + * Since LPC memory belongs to a link, the whole LPC memory available
> + * on the link bust be mapped in order to make it accessible to a device.
> + *
> + * @link_handle: The OpenCAPI link handle
> + * @pdev: A device that is on the link
> + */
> +u64 ocxl_link_lpc_map(void *link_handle, struct pci_dev *pdev);
> +
> +/**
> + * ocxl_link_lpc_release() - Release the LPC memory device for an OpenCAPI device
> + *
> + * Offlines LPC memory on an OpenCAPI link for a device. If this is the
> + * last device on the link to release the memory, unmap it from the link.
> + *
> + * @link_handle: The OpenCAPI link handle
> + * @pdev: A device that is on the link
> + */
> +void ocxl_link_lpc_release(void *link_handle, struct pci_dev *pdev);
> +
>   #endif /* _OCXL_INTERNAL_H_ */
>
Jonathan Cameron Feb. 3, 2020, 12:37 p.m. UTC | #2
On Tue, 3 Dec 2019 14:46:34 +1100
Alastair D'Silva <alastair@au1.ibm.com> wrote:

> From: Alastair D'Silva <alastair@d-silva.org>
> 
> Tally up the LPC memory on an OpenCAPI link & allow it to be mapped
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
Hi Alastair,

A few trivial comments inline.

Jonathan

> ---
>  drivers/misc/ocxl/core.c          | 10 ++++++
>  drivers/misc/ocxl/link.c          | 60 +++++++++++++++++++++++++++++++
>  drivers/misc/ocxl/ocxl_internal.h | 33 +++++++++++++++++
>  3 files changed, 103 insertions(+)
> 
> diff --git a/drivers/misc/ocxl/core.c b/drivers/misc/ocxl/core.c
> index b7a09b21ab36..2531c6cf19a0 100644
> --- a/drivers/misc/ocxl/core.c
> +++ b/drivers/misc/ocxl/core.c
> @@ -230,8 +230,18 @@ static int configure_afu(struct ocxl_afu *afu, u8 afu_idx, struct pci_dev *dev)
>  	if (rc)
>  		goto err_free_pasid;
>  
> +	if (afu->config.lpc_mem_size || afu->config.special_purpose_mem_size) {
> +		rc = ocxl_link_add_lpc_mem(afu->fn->link, afu->config.lpc_mem_offset,
> +					   afu->config.lpc_mem_size +
> +					   afu->config.special_purpose_mem_size);
> +		if (rc)
> +			goto err_free_mmio;
> +	}
> +
>  	return 0;
>  
> +err_free_mmio:
> +	unmap_mmio_areas(afu);
>  err_free_pasid:
>  	reclaim_afu_pasid(afu);
>  err_free_actag:
> diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
> index 58d111afd9f6..d8503f0dc6ec 100644
> --- a/drivers/misc/ocxl/link.c
> +++ b/drivers/misc/ocxl/link.c
> @@ -84,6 +84,11 @@ struct ocxl_link {
>  	int dev;
>  	atomic_t irq_available;
>  	struct spa *spa;
> +	struct mutex lpc_mem_lock;

Always a good idea to explicitly document what a lock is intended to protect.

> +	u64 lpc_mem_sz; /* Total amount of LPC memory presented on the link */
> +	u64 lpc_mem;
> +	int lpc_consumers;
> +
>  	void *platform_data;
>  };
>  static struct list_head links_list = LIST_HEAD_INIT(links_list);
> @@ -396,6 +401,8 @@ static int alloc_link(struct pci_dev *dev, int PE_mask, struct ocxl_link **out_l
>  	if (rc)
>  		goto err_spa;
>  
> +	mutex_init(&link->lpc_mem_lock);
> +
>  	/* platform specific hook */
>  	rc = pnv_ocxl_spa_setup(dev, link->spa->spa_mem, PE_mask,
>  				&link->platform_data);
> @@ -711,3 +718,56 @@ void ocxl_link_free_irq(void *link_handle, int hw_irq)
>  	atomic_inc(&link->irq_available);
>  }
>  EXPORT_SYMBOL_GPL(ocxl_link_free_irq);
> +
> +int ocxl_link_add_lpc_mem(void *link_handle, u64 offset, u64 size)
> +{
> +	struct ocxl_link *link = (struct ocxl_link *) link_handle;
> +
> +	// Check for overflow

Stray c++ style comment.

> +	if (offset > (offset + size))
> +		return -EINVAL;
> +
> +	mutex_lock(&link->lpc_mem_lock);
> +	link->lpc_mem_sz = max(link->lpc_mem_sz, offset + size);
> +
> +	mutex_unlock(&link->lpc_mem_lock);
> +
> +	return 0;
> +}
> +
> +u64 ocxl_link_lpc_map(void *link_handle, struct pci_dev *pdev)
> +{
> +	struct ocxl_link *link = (struct ocxl_link *) link_handle;
> +	u64 lpc_mem;
> +
> +	mutex_lock(&link->lpc_mem_lock);
> +	if (link->lpc_mem) {

If you don't modify this later in the series (I haven't read it all yet :),
it rather feels like it would be more compact and just as readable as
something like...

	if (!link->lpc_mem)
		link->lpc_mem = pnv_ocxl...

	if (link->lpc_mem)
		link->lpc_consumers++;
	mutex_unlock(&link->lpc_mem_lock);
		
	return link->lpc_mem;

> +		lpc_mem = link->lpc_mem;
> +
> +		link->lpc_consumers++;
> +		mutex_unlock(&link->lpc_mem_lock);
> +		return lpc_mem;
> +	}
> +
> +	link->lpc_mem = pnv_ocxl_platform_lpc_setup(pdev, link->lpc_mem_sz);
> +	if (link->lpc_mem)
> +		link->lpc_consumers++;
> +	lpc_mem = link->lpc_mem;
> +	mutex_unlock(&link->lpc_mem_lock);
> +
> +	return lpc_mem;
> +}
> +
> +void ocxl_link_lpc_release(void *link_handle, struct pci_dev *pdev)
> +{
> +	struct ocxl_link *link = (struct ocxl_link *) link_handle;
> +
> +	mutex_lock(&link->lpc_mem_lock);
> +	WARN_ON(--link->lpc_consumers < 0);
> +	if (link->lpc_consumers == 0) {
> +		pnv_ocxl_platform_lpc_release(pdev);
> +		link->lpc_mem = 0;
> +	}
> +
> +	mutex_unlock(&link->lpc_mem_lock);
> +}
> diff --git a/drivers/misc/ocxl/ocxl_internal.h b/drivers/misc/ocxl/ocxl_internal.h
> index 97415afd79f3..20b417e00949 100644
> --- a/drivers/misc/ocxl/ocxl_internal.h
> +++ b/drivers/misc/ocxl/ocxl_internal.h
> @@ -141,4 +141,37 @@ int ocxl_irq_offset_to_id(struct ocxl_context *ctx, u64 offset);
>  u64 ocxl_irq_id_to_offset(struct ocxl_context *ctx, int irq_id);
>  void ocxl_afu_irq_free_all(struct ocxl_context *ctx);
>  
> +/**
> + * ocxl_link_add_lpc_mem() - Increment the amount of memory required by an OpenCAPI link
> + *
> + * @link_handle: The OpenCAPI link handle
> + * @offset: The offset of the memory to add
> + * @size: The amount of memory to increment by
> + *
> + * Return 0 on success, negative on overflow
> + */
> +int ocxl_link_add_lpc_mem(void *link_handle, u64 offset, u64 size);
> +
> +/**
> + * ocxl_link_lpc_map() - Map the LPC memory for an OpenCAPI device
> + *
> + * Since LPC memory belongs to a link, the whole LPC memory available
> + * on the link bust be mapped in order to make it accessible to a device.

must

> + *
> + * @link_handle: The OpenCAPI link handle
> + * @pdev: A device that is on the link
> + */
> +u64 ocxl_link_lpc_map(void *link_handle, struct pci_dev *pdev);
> +
> +/**
> + * ocxl_link_lpc_release() - Release the LPC memory device for an OpenCAPI device
> + *
> + * Offlines LPC memory on an OpenCAPI link for a device. If this is the
> + * last device on the link to release the memory, unmap it from the link.
> + *
> + * @link_handle: The OpenCAPI link handle
> + * @pdev: A device that is on the link
> + */
> +void ocxl_link_lpc_release(void *link_handle, struct pci_dev *pdev);
> +
>  #endif /* _OCXL_INTERNAL_H_ */
Alastair D'Silva Feb. 19, 2020, 12:01 a.m. UTC | #3
On Mon, 2020-02-03 at 12:37 +0000, Jonathan Cameron wrote:
> On Tue, 3 Dec 2019 14:46:34 +1100
> Alastair D'Silva <alastair@au1.ibm.com> wrote:
> 
> > From: Alastair D'Silva <alastair@d-silva.org>
> > 
> > Tally up the LPC memory on an OpenCAPI link & allow it to be mapped
> > 
> > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> Hi Alastair,
> 
> A few trivial comments inline.
> 
> Jonathan
> 
> > ---
> >  drivers/misc/ocxl/core.c          | 10 ++++++
> >  drivers/misc/ocxl/link.c          | 60
> > +++++++++++++++++++++++++++++++
> >  drivers/misc/ocxl/ocxl_internal.h | 33 +++++++++++++++++
> >  3 files changed, 103 insertions(+)
> > 
> > diff --git a/drivers/misc/ocxl/core.c b/drivers/misc/ocxl/core.c
> > index b7a09b21ab36..2531c6cf19a0 100644
> > --- a/drivers/misc/ocxl/core.c
> > +++ b/drivers/misc/ocxl/core.c
> > @@ -230,8 +230,18 @@ static int configure_afu(struct ocxl_afu *afu,
> > u8 afu_idx, struct pci_dev *dev)
> >  	if (rc)
> >  		goto err_free_pasid;
> >  
> > +	if (afu->config.lpc_mem_size || afu-
> > >config.special_purpose_mem_size) {
> > +		rc = ocxl_link_add_lpc_mem(afu->fn->link, afu-
> > >config.lpc_mem_offset,
> > +					   afu->config.lpc_mem_size +
> > +					   afu-
> > >config.special_purpose_mem_size);
> > +		if (rc)
> > +			goto err_free_mmio;
> > +	}
> > +
> >  	return 0;
> >  
> > +err_free_mmio:
> > +	unmap_mmio_areas(afu);
> >  err_free_pasid:
> >  	reclaim_afu_pasid(afu);
> >  err_free_actag:
> > diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
> > index 58d111afd9f6..d8503f0dc6ec 100644
> > --- a/drivers/misc/ocxl/link.c
> > +++ b/drivers/misc/ocxl/link.c
> > @@ -84,6 +84,11 @@ struct ocxl_link {
> >  	int dev;
> >  	atomic_t irq_available;
> >  	struct spa *spa;
> > +	struct mutex lpc_mem_lock;
> 
> Always a good idea to explicitly document what a lock is intended to
> protect.
> 
Ok

> > +	u64 lpc_mem_sz; /* Total amount of LPC memory presented on the
> > link */
> > +	u64 lpc_mem;
> > +	int lpc_consumers;
> > +
> >  	void *platform_data;
> >  };
> >  static struct list_head links_list = LIST_HEAD_INIT(links_list);
> > @@ -396,6 +401,8 @@ static int alloc_link(struct pci_dev *dev, int
> > PE_mask, struct ocxl_link **out_l
> >  	if (rc)
> >  		goto err_spa;
> >  
> > +	mutex_init(&link->lpc_mem_lock);
> > +
> >  	/* platform specific hook */
> >  	rc = pnv_ocxl_spa_setup(dev, link->spa->spa_mem, PE_mask,
> >  				&link->platform_data);
> > @@ -711,3 +718,56 @@ void ocxl_link_free_irq(void *link_handle, int
> > hw_irq)
> >  	atomic_inc(&link->irq_available);
> >  }
> >  EXPORT_SYMBOL_GPL(ocxl_link_free_irq);
> > +
> > +int ocxl_link_add_lpc_mem(void *link_handle, u64 offset, u64 size)
> > +{
> > +	struct ocxl_link *link = (struct ocxl_link *) link_handle;
> > +
> > +	// Check for overflow
> 
> Stray c++ style comment.
> 
This is permitted in powerpc.

> > +	if (offset > (offset + size))
> > +		return -EINVAL;
> > +
> > +	mutex_lock(&link->lpc_mem_lock);
> > +	link->lpc_mem_sz = max(link->lpc_mem_sz, offset + size);
> > +
> > +	mutex_unlock(&link->lpc_mem_lock);
> > +
> > +	return 0;
> > +}
> > +
> > +u64 ocxl_link_lpc_map(void *link_handle, struct pci_dev *pdev)
> > +{
> > +	struct ocxl_link *link = (struct ocxl_link *) link_handle;
> > +	u64 lpc_mem;
> > +
> > +	mutex_lock(&link->lpc_mem_lock);
> > +	if (link->lpc_mem) {
> 
> If you don't modify this later in the series (I haven't read it all
> yet :),
> it rather feels like it would be more compact and just as readable as
> something like...
> 
> 	if (!link->lpc_mem)
> 		link->lpc_mem = pnv_ocxl...
> 
> 	if (link->lpc_mem)
> 		link->lpc_consumers++;
> 	mutex_unlock(&link->lpc_mem_lock);
> 		
> 	return link->lpc_mem;
> 

Agreed, thanks.

> > +		lpc_mem = link->lpc_mem;
> > +
> > +		link->lpc_consumers++;
> > +		mutex_unlock(&link->lpc_mem_lock);
> > +		return lpc_mem;
> > +	}
> > +
> > +	link->lpc_mem = pnv_ocxl_platform_lpc_setup(pdev, link-
> > >lpc_mem_sz);
> > +	if (link->lpc_mem)
> > +		link->lpc_consumers++;
> > +	lpc_mem = link->lpc_mem;
> > +	mutex_unlock(&link->lpc_mem_lock);
> > +
> > +	return lpc_mem;
> > +}
> > +
> > +void ocxl_link_lpc_release(void *link_handle, struct pci_dev
> > *pdev)
> > +{
> > +	struct ocxl_link *link = (struct ocxl_link *) link_handle;
> > +
> > +	mutex_lock(&link->lpc_mem_lock);
> > +	WARN_ON(--link->lpc_consumers < 0);
> > +	if (link->lpc_consumers == 0) {
> > +		pnv_ocxl_platform_lpc_release(pdev);
> > +		link->lpc_mem = 0;
> > +	}
> > +
> > +	mutex_unlock(&link->lpc_mem_lock);
> > +}
> > diff --git a/drivers/misc/ocxl/ocxl_internal.h
> > b/drivers/misc/ocxl/ocxl_internal.h
> > index 97415afd79f3..20b417e00949 100644
> > --- a/drivers/misc/ocxl/ocxl_internal.h
> > +++ b/drivers/misc/ocxl/ocxl_internal.h
> > @@ -141,4 +141,37 @@ int ocxl_irq_offset_to_id(struct ocxl_context
> > *ctx, u64 offset);
> >  u64 ocxl_irq_id_to_offset(struct ocxl_context *ctx, int irq_id);
> >  void ocxl_afu_irq_free_all(struct ocxl_context *ctx);
> >  
> > +/**
> > + * ocxl_link_add_lpc_mem() - Increment the amount of memory
> > required by an OpenCAPI link
> > + *
> > + * @link_handle: The OpenCAPI link handle
> > + * @offset: The offset of the memory to add
> > + * @size: The amount of memory to increment by
> > + *
> > + * Return 0 on success, negative on overflow
> > + */
> > +int ocxl_link_add_lpc_mem(void *link_handle, u64 offset, u64
> > size);
> > +
> > +/**
> > + * ocxl_link_lpc_map() - Map the LPC memory for an OpenCAPI device
> > + *
> > + * Since LPC memory belongs to a link, the whole LPC memory
> > available
> > + * on the link bust be mapped in order to make it accessible to a
> > device.
> 
> must

Whoops :)
> 
> > + *
> > + * @link_handle: The OpenCAPI link handle
> > + * @pdev: A device that is on the link
> > + */
> > +u64 ocxl_link_lpc_map(void *link_handle, struct pci_dev *pdev);
> > +
> > +/**
> > + * ocxl_link_lpc_release() - Release the LPC memory device for an
> > OpenCAPI device
> > + *
> > + * Offlines LPC memory on an OpenCAPI link for a device. If this
> > is the
> > + * last device on the link to release the memory, unmap it from
> > the link.
> > + *
> > + * @link_handle: The OpenCAPI link handle
> > + * @pdev: A device that is on the link
> > + */
> > +void ocxl_link_lpc_release(void *link_handle, struct pci_dev
> > *pdev);
> > +
> >  #endif /* _OCXL_INTERNAL_H_ */
diff mbox series

Patch

diff --git a/drivers/misc/ocxl/core.c b/drivers/misc/ocxl/core.c
index b7a09b21ab36..2531c6cf19a0 100644
--- a/drivers/misc/ocxl/core.c
+++ b/drivers/misc/ocxl/core.c
@@ -230,8 +230,18 @@  static int configure_afu(struct ocxl_afu *afu, u8 afu_idx, struct pci_dev *dev)
 	if (rc)
 		goto err_free_pasid;
 
+	if (afu->config.lpc_mem_size || afu->config.special_purpose_mem_size) {
+		rc = ocxl_link_add_lpc_mem(afu->fn->link, afu->config.lpc_mem_offset,
+					   afu->config.lpc_mem_size +
+					   afu->config.special_purpose_mem_size);
+		if (rc)
+			goto err_free_mmio;
+	}
+
 	return 0;
 
+err_free_mmio:
+	unmap_mmio_areas(afu);
 err_free_pasid:
 	reclaim_afu_pasid(afu);
 err_free_actag:
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index 58d111afd9f6..d8503f0dc6ec 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -84,6 +84,11 @@  struct ocxl_link {
 	int dev;
 	atomic_t irq_available;
 	struct spa *spa;
+	struct mutex lpc_mem_lock;
+	u64 lpc_mem_sz; /* Total amount of LPC memory presented on the link */
+	u64 lpc_mem;
+	int lpc_consumers;
+
 	void *platform_data;
 };
 static struct list_head links_list = LIST_HEAD_INIT(links_list);
@@ -396,6 +401,8 @@  static int alloc_link(struct pci_dev *dev, int PE_mask, struct ocxl_link **out_l
 	if (rc)
 		goto err_spa;
 
+	mutex_init(&link->lpc_mem_lock);
+
 	/* platform specific hook */
 	rc = pnv_ocxl_spa_setup(dev, link->spa->spa_mem, PE_mask,
 				&link->platform_data);
@@ -711,3 +718,56 @@  void ocxl_link_free_irq(void *link_handle, int hw_irq)
 	atomic_inc(&link->irq_available);
 }
 EXPORT_SYMBOL_GPL(ocxl_link_free_irq);
+
+int ocxl_link_add_lpc_mem(void *link_handle, u64 offset, u64 size)
+{
+	struct ocxl_link *link = (struct ocxl_link *) link_handle;
+
+	// Check for overflow
+	if (offset > (offset + size))
+		return -EINVAL;
+
+	mutex_lock(&link->lpc_mem_lock);
+	link->lpc_mem_sz = max(link->lpc_mem_sz, offset + size);
+
+	mutex_unlock(&link->lpc_mem_lock);
+
+	return 0;
+}
+
+u64 ocxl_link_lpc_map(void *link_handle, struct pci_dev *pdev)
+{
+	struct ocxl_link *link = (struct ocxl_link *) link_handle;
+	u64 lpc_mem;
+
+	mutex_lock(&link->lpc_mem_lock);
+	if (link->lpc_mem) {
+		lpc_mem = link->lpc_mem;
+
+		link->lpc_consumers++;
+		mutex_unlock(&link->lpc_mem_lock);
+		return lpc_mem;
+	}
+
+	link->lpc_mem = pnv_ocxl_platform_lpc_setup(pdev, link->lpc_mem_sz);
+	if (link->lpc_mem)
+		link->lpc_consumers++;
+	lpc_mem = link->lpc_mem;
+	mutex_unlock(&link->lpc_mem_lock);
+
+	return lpc_mem;
+}
+
+void ocxl_link_lpc_release(void *link_handle, struct pci_dev *pdev)
+{
+	struct ocxl_link *link = (struct ocxl_link *) link_handle;
+
+	mutex_lock(&link->lpc_mem_lock);
+	WARN_ON(--link->lpc_consumers < 0);
+	if (link->lpc_consumers == 0) {
+		pnv_ocxl_platform_lpc_release(pdev);
+		link->lpc_mem = 0;
+	}
+
+	mutex_unlock(&link->lpc_mem_lock);
+}
diff --git a/drivers/misc/ocxl/ocxl_internal.h b/drivers/misc/ocxl/ocxl_internal.h
index 97415afd79f3..20b417e00949 100644
--- a/drivers/misc/ocxl/ocxl_internal.h
+++ b/drivers/misc/ocxl/ocxl_internal.h
@@ -141,4 +141,37 @@  int ocxl_irq_offset_to_id(struct ocxl_context *ctx, u64 offset);
 u64 ocxl_irq_id_to_offset(struct ocxl_context *ctx, int irq_id);
 void ocxl_afu_irq_free_all(struct ocxl_context *ctx);
 
+/**
+ * ocxl_link_add_lpc_mem() - Increment the amount of memory required by an OpenCAPI link
+ *
+ * @link_handle: The OpenCAPI link handle
+ * @offset: The offset of the memory to add
+ * @size: The amount of memory to increment by
+ *
+ * Return 0 on success, negative on overflow
+ */
+int ocxl_link_add_lpc_mem(void *link_handle, u64 offset, u64 size);
+
+/**
+ * ocxl_link_lpc_map() - Map the LPC memory for an OpenCAPI device
+ *
+ * Since LPC memory belongs to a link, the whole LPC memory available
+ * on the link bust be mapped in order to make it accessible to a device.
+ *
+ * @link_handle: The OpenCAPI link handle
+ * @pdev: A device that is on the link
+ */
+u64 ocxl_link_lpc_map(void *link_handle, struct pci_dev *pdev);
+
+/**
+ * ocxl_link_lpc_release() - Release the LPC memory device for an OpenCAPI device
+ *
+ * Offlines LPC memory on an OpenCAPI link for a device. If this is the
+ * last device on the link to release the memory, unmap it from the link.
+ *
+ * @link_handle: The OpenCAPI link handle
+ * @pdev: A device that is on the link
+ */
+void ocxl_link_lpc_release(void *link_handle, struct pci_dev *pdev);
+
 #endif /* _OCXL_INTERNAL_H_ */