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

Alastair D'Silva
2020-02-19T04:47:33Z

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