linux-kernel - Re: [PATCH 4/5] ocxl: Add functions to map/unmap LPC memory

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Date:   Thu, 26 Sep 2019 12:59:25 +1000
From:   "Alastair D'Silva" <alastair@....ibm.com>
To:     Frederic Barrat <fbarrat@...ux.ibm.com>
Cc:     Andrew Donnellan <ajd@...ux.ibm.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, Nicholas Piggin <npiggin@...il.com>,
        Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Anju T Sudhakar <anju@...ux.vnet.ibm.com>,
        Paul Mackerras <paulus@...ba.org>,
        Cédric Le Goater <clg@...d.org>,
        Vaibhav Jain <vaibhav@...ux.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linuxppc-dev@...ts.ozlabs.org,
        Allison Randal <allison@...utok.net>,
        David Gibson <david@...son.dropbear.id.au>
Subject: Re: [PATCH 4/5] ocxl: Add functions to map/unmap LPC memory

On Mon, 2019-09-23 at 13:39 +0200, Frederic Barrat wrote:
> 
> 
> > diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
> > index 2874811a4398..9e303a5f4d85 100644
> > --- a/drivers/misc/ocxl/link.c
> > +++ b/drivers/misc/ocxl/link.c
> > @@ -738,7 +738,7 @@ int ocxl_link_add_lpc_mem(void *link_handle,
> > u64 size)
> >   }
> >   EXPORT_SYMBOL_GPL(ocxl_link_add_lpc_mem);
> >   
> > -u64 ocxl_link_lpc_map(void *link_handle, struct pci_dev *pdev)
> > +u64 ocxl_link_lpc_online(void *link_handle, struct pci_dev *pdev)
> >   {
> >   	struct ocxl_link *link = (struct ocxl_link *) link_handle;
> >   
> 
> A bit of a nitpick, but is there any specific reason to rename with 
> "online" suffix? I'm discovering it myself, but with memory hotplug, 
> "onlining" seems to refer to the second, a.k.a logical memory
> hotplug 
> phase (as described in Documentation/admin-guide/mm/memory-
> hotplug.rst). 
> We'll need to worry about it, but the function here is really doing
> the 
> first phase, a.k.a physical memory hotplug.
> 
>    Fred

It's been a while since I wrote that, so I can't remember why, but your
reasoning is sound, I'll drop the rename.

> 
> 
> > @@ -759,7 +759,7 @@ u64 ocxl_link_lpc_map(void *link_handle, struct
> > pci_dev *pdev)
> >   	return link->lpc_mem;
> >   }
> >   
> > -void ocxl_link_lpc_release(void *link_handle, struct pci_dev
> > *pdev)
> > +void ocxl_link_lpc_offline(void *link_handle, struct pci_dev
> > *pdev)
> >   {
> >   	struct ocxl_link *link = (struct ocxl_link *) link_handle;
> >   
> > diff --git a/drivers/misc/ocxl/ocxl_internal.h
> > b/drivers/misc/ocxl/ocxl_internal.h
> > index db2647a90fc8..5656a4aab5b7 100644
> > --- a/drivers/misc/ocxl/ocxl_internal.h
> > +++ b/drivers/misc/ocxl/ocxl_internal.h
> > @@ -52,6 +52,12 @@ struct ocxl_afu {
> >   	void __iomem *global_mmio_ptr;
> >   	u64 pp_mmio_start;
> >   	void *private;
> > +	u64 lpc_base_addr; /* Covers both LPC & special purpose memory
> > */
> > +	struct bin_attribute attr_global_mmio;
> > +	struct bin_attribute attr_lpc_mem;
> > +	struct resource lpc_res;
> > +	struct bin_attribute attr_special_purpose_mem;
> > +	struct resource special_purpose_res;
> >   };
> >   
> >   enum ocxl_context_status {
> > @@ -170,7 +176,7 @@ extern u64 ocxl_link_get_lpc_mem_sz(void
> > *link_handle);
> >    * @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);
> > +u64 ocxl_link_lpc_online(void *link_handle, struct pci_dev *pdev);
> >   
> >   /**
> >    * Release the LPC memory device for an OpenCAPI device
> > @@ -181,6 +187,6 @@ u64 ocxl_link_lpc_map(void *link_handle, struct
> > pci_dev *pdev);
> >    * @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);
> > +void ocxl_link_lpc_offline(void *link_handle, struct pci_dev
> > *pdev);
> >   
> >   #endif /* _OCXL_INTERNAL_H_ */
> > diff --git a/include/misc/ocxl.h b/include/misc/ocxl.h
> > index 06dd5839e438..a1897737908d 100644
> > --- a/include/misc/ocxl.h
> > +++ b/include/misc/ocxl.h
> > @@ -212,6 +212,24 @@ int ocxl_irq_set_handler(struct ocxl_context
> > *ctx, int irq_id,
> >   
> >   // AFU Metadata
> >   
> > +/**
> > + * Map the LPC system & special purpose memory for an AFU
> > + *
> > + * Do not call this during device discovery, as there may me
> > multiple
> > + * devices on a link, and the memory is mapped for the whole link,
> > not
> > + * just one device. It should only be called after all devices
> > have
> > + * registered their memory on the link.
> > + *
> > + * afu: The AFU that has the LPC memory to map
> > + */
> > +extern int ocxl_map_lpc_mem(struct ocxl_afu *afu);
> > +
> > +/**
> > + * Get the physical address range of LPC memory for an AFU
> > + * afu: The AFU associated with the LPC memory
> > + */
> > +extern struct resource *ocxl_afu_lpc_mem(struct ocxl_afu *afu);
> > +
> >   /**
> >    * Get a pointer to the config for an AFU
> >    *
> > 
-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819