RE: [PATCH v2 12/27] nvdimm/ocxl: Read the capability registers & wait for device ready

["Alastair D'Silva" <alastair@au1.ibm.com>]

On Mon, 2020-02-03 at 13:23 +0000, Jonathan Cameron wrote:
> On Tue, 3 Dec 2019 14:46:40 +1100
> Alastair D'Silva <alastair@au1.ibm.com> wrote:
> 
> > From: Alastair D'Silva <alastair@d-silva.org>
> > 
> > This patch reads timeouts & firmware version from the controller,
> > and
> > uses those timeouts to wait for the controller to report that it is
> > ready
> > before handing the memory over to libnvdimm.
> > 
> > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> > ---
> >  drivers/nvdimm/ocxl/Makefile       |  2 +-
> >  drivers/nvdimm/ocxl/scm.c          | 84
> > ++++++++++++++++++++++++++++++
> >  drivers/nvdimm/ocxl/scm_internal.c | 19 +++++++
> >  drivers/nvdimm/ocxl/scm_internal.h | 24 +++++++++
> >  4 files changed, 128 insertions(+), 1 deletion(-)
> >  create mode 100644 drivers/nvdimm/ocxl/scm_internal.c
> > 
> > diff --git a/drivers/nvdimm/ocxl/Makefile
> > b/drivers/nvdimm/ocxl/Makefile
> > index 74a1bd98848e..9b6e31f0eb3e 100644
> > --- a/drivers/nvdimm/ocxl/Makefile
> > +++ b/drivers/nvdimm/ocxl/Makefile
> > @@ -4,4 +4,4 @@ ccflags-$(CONFIG_PPC_WERROR)	+= -Werror
> >  
> >  obj-$(CONFIG_OCXL_SCM) += ocxlscm.o
> >  
> > -ocxlscm-y := scm.o
> > +ocxlscm-y := scm.o scm_internal.o
> > diff --git a/drivers/nvdimm/ocxl/scm.c b/drivers/nvdimm/ocxl/scm.c
> > index 571058a9e7b8..8088f65c289e 100644
> > --- a/drivers/nvdimm/ocxl/scm.c
> > +++ b/drivers/nvdimm/ocxl/scm.c
> > @@ -7,6 +7,7 @@
> >  
> >  #include <linux/module.h>
> >  #include <misc/ocxl.h>
> > +#include <linux/delay.h>
> >  #include <linux/ndctl.h>
> >  #include <linux/mm_types.h>
> >  #include <linux/memory_hotplug.h>
> > @@ -266,6 +267,30 @@ static int scm_register_lpc_mem(struct
> > scm_data *scm_data)
> >  	return 0;
> >  }
> >  
> > +/**
> > + * scm_is_usable() - Is a controller usable?
> > + * @scm_data: a pointer to the SCM device data
> > + * Return: true if the controller is usable
> > + */
> > +static bool scm_is_usable(const struct scm_data *scm_data)
> > +{
> > +	u64 chi = 0;
> > +	int rc = scm_chi(scm_data, &chi);
> > +
> > +	if (!(chi & GLOBAL_MMIO_CHI_CRDY)) {
> > +		dev_err(&scm_data->dev, "SCM controller is not
> > ready.\n");
> > +		return false;
> > +	}
> > +
> > +	if (!(chi & GLOBAL_MMIO_CHI_MA)) {
> > +		dev_err(&scm_data->dev,
> > +			"SCM controller does not have memory
> > available.\n");
> > +		return false;
> > +	}
> > +
> > +	return true;
> > +}
> > +
> >  /**
> >   * allocate_scm_minor() - Allocate a minor number to use for an
> > SCM device
> >   * @scm_data: The SCM device to associate the minor with
> > @@ -380,6 +405,48 @@ static void scm_remove(struct pci_dev *pdev)
> >  	}
> >  }
> >  
> > +/**
> > + * read_device_metadata() - Retrieve config information from the
> > AFU and save it for future use
> > + * @scm_data: the SCM metadata
> > + * Return: 0 on success, negative on failure
> > + */
> > +static int read_device_metadata(struct scm_data *scm_data)
> > +{
> > +	u64 val;
> > +	int rc;
> > +
> > +	rc = ocxl_global_mmio_read64(scm_data->ocxl_afu,
> > GLOBAL_MMIO_CCAP0,
> > +				     OCXL_LITTLE_ENDIAN, &val);
> > +	if (rc)
> > +		return rc;
> > +
> > +	scm_data->scm_revision = val & 0xFFFF;
> > +	scm_data->read_latency = (val >> 32) & 0xFF;
> > +	scm_data->readiness_timeout = (val >> 48) & 0xff;
> > +	scm_data->memory_available_timeout = val >> 52;
> 
> This overlaps with the masked region for readiness_timeout.  I'll
> guess the maks
> on that should be 0xF.
> 
Good catch, you're correct.

> > +
> > +	rc = ocxl_global_mmio_read64(scm_data->ocxl_afu,
> > GLOBAL_MMIO_CCAP1,
> > +				     OCXL_LITTLE_ENDIAN, &val);
> > +	if (rc)
> > +		return rc;
> > +
> > +	scm_data->max_controller_dump_size = val & 0xFFFFFFFF;
> > +
> > +	// Extract firmware version text
> > +	rc = ocxl_global_mmio_read64(scm_data->ocxl_afu,
> > GLOBAL_MMIO_FWVER,
> > +				     OCXL_HOST_ENDIAN, (u64 *)scm_data-
> > >fw_version);
> > +	if (rc)
> > +		return rc;
> > +
> > +	scm_data->fw_version[8] = '\0';
> > +
> > +	dev_info(&scm_data->dev,
> > +		 "Firmware version '%s' SCM revision %d:%d\n",
> > scm_data->fw_version,
> > +		 scm_data->scm_revision >> 4, scm_data->scm_revision &
> > 0x0F);
> > +
> > +	return 0;
> > +}
> > +
> >  /**
> >   * scm_probe_function_0 - Set up function 0 for an OpenCAPI
> > Storage Class Memory device
> >   * This is important as it enables templates higher than 0 across
> > all other functions,
> > @@ -420,6 +487,8 @@ static int scm_probe_function_0(struct pci_dev
> > *pdev)
> >  static int scm_probe(struct pci_dev *pdev, const struct
> > pci_device_id *ent)
> >  {
> >  	struct scm_data *scm_data = NULL;
> > +	int elapsed;
> > +	u16 timeout;
> >  
> >  	if (PCI_FUNC(pdev->devfn) == 0)
> >  		return scm_probe_function_0(pdev);
> > @@ -469,6 +538,21 @@ static int scm_probe(struct pci_dev *pdev,
> > const struct pci_device_id *ent)
> >  		goto err;
> >  	}
> >  
> > +	if (read_device_metadata(scm_data)) {
> > +		dev_err(&pdev->dev, "Could not read SCM device
> > metadata\n");
> > +		goto err;
> > +	}
> > +
> > +	elapsed = 0;
> > +	timeout = scm_data->readiness_timeout + scm_data-
> > >memory_available_timeout;
> > +	while (!scm_is_usable(scm_data)) {
> > +		if (elapsed++ > timeout) {
> > +			dev_warn(&scm_data->dev, "SCM ready
> > timeout.\n");
> > +			goto err;
> > +		}
> > +
> > +		msleep(1000);
> > +	}
> >  	if (scm_register_lpc_mem(scm_data)) {
> >  		dev_err(&pdev->dev, "Could not register OCXL SCM memory
> > with libnvdimm\n");
> >  		goto err;
> > diff --git a/drivers/nvdimm/ocxl/scm_internal.c
> > b/drivers/nvdimm/ocxl/scm_internal.c
> > new file mode 100644
> > index 000000000000..72d3c0e7d846
> > --- /dev/null
> > +++ b/drivers/nvdimm/ocxl/scm_internal.c
> > @@ -0,0 +1,19 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +// Copyright 2019 IBM Corp.
> > +
> > +#include <misc/ocxl.h>
> > +#include <linux/delay.h>
> > +#include "scm_internal.h"
> > +
> > +int scm_chi(const struct scm_data *scm_data, u64 *chi)
> > +{
> > +	u64 val;
> > +	int rc = ocxl_global_mmio_read64(scm_data->ocxl_afu,
> > GLOBAL_MMIO_CHI,
> > +					 OCXL_LITTLE_ENDIAN, &val);
> > +	if (rc)
> > +		return rc;
> > +
> > +	*chi = val;
> > +
> > +	return 0;
> > +}
> > diff --git a/drivers/nvdimm/ocxl/scm_internal.h
> > b/drivers/nvdimm/ocxl/scm_internal.h
> > index d6ab361f5de9..584450f55e30 100644
> > --- a/drivers/nvdimm/ocxl/scm_internal.h
> > +++ b/drivers/nvdimm/ocxl/scm_internal.h
> > @@ -97,4 +97,28 @@ struct scm_data {
> >  	void *metadata_addr;
> >  	struct resource scm_res;
> >  	struct nd_region *nd_region;
> > +	char fw_version[8+1];
> > +
> > +	u32 max_controller_dump_size;
> > +	u16 scm_revision; // major/minor
> > +	u8 readiness_timeout;  /* The worst case time (in seconds) that
> > the host shall
> > +				* wait for the controller to become
> > operational following a reset (CHI.CRDY).
> > +				*/
> > +	u8 memory_available_timeout;   /* The worst case time (in
> > seconds) that the host shall
> > +					* wait for memory to become
> > available following a reset (CHI.MA).
> > +					*/
> > +
> > +	u16 read_latency; /* The nominal measure of latency (in
> > nanoseconds)
> > +			   * associated with an unassisted read of a
> > memory block.
> > +			   * This represents the capability of the raw
> > media technology without assistance
> > +			   */
> >  };
> > +
> > +/**
> > + * scm_chi() - Get the value of the CHI register
> > + * @scm_data: The SCM metadata
> > + * @chi: returns the CHI value
> > + *
> > + * Returns 0 on success, negative on error
> > + */
> > +int scm_chi(const struct scm_data *scm_data, u64 *chi);
-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819