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

> +
> + 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);


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