Re: [RFC PATCH v6 12/12] memory: RAS2: Add memory RAS2 driver

Jonathan Cameron
2024-02-20T16:12:37Z

On Thu, 15 Feb 2024 19:14:54 +0800
<shiju.jose@huawei.com> wrote:

> From: Shiju Jose <shiju.jose@huawei.com>
>
> Memory RAS2 driver binds to the platform device add by the ACPI RAS2
> driver.
> Driver registers the PCC channel for communicating with the ACPI compliant
> platform that contains RAS2 command support in the hardware.
>
> Add interface functions to support configuring the parameters of HW patrol
> scrubs in the system, which exposed to the kernel via the RAS2 and PCC,
> using the RAS2 commands.
>
> Add support for RAS2 platform devices to register with scrub subsystem
> driver. This enables user to configure the parameters of HW patrol scrubs,
> which exposed to the kernel via the RAS2 table, through the scrub sysfs
> attributes.
>
> Open Question:
> Sysfs scrub control attribute "enable_background_scrub" is added for RAS2,
> based on the feedback from Bill Schwartz <wschwartz@amperecomputing.com
> on v4 to enable/disable the background_scrubbing in the platform as defined in the
> “Configure Scrub Parameters [INPUT]“ field in RAS2 Table 5.87: Parameter Block
> Structure for PATROL_SCRUB.
> Is it a right approach to support "enable_background_scrub" in the sysfs
> scrub control?

Does anyone know what this means? IIUC patrol scrub is always background...

>
> Signed-off-by: Shiju Jose <shiju.jose@huawei.com>

A few minor comments inline. Rushed review as out of time for today though
so may have missed stuff.

> diff --git a/drivers/memory/rasf_common.c b/drivers/memory/rasf_common.c
> new file mode 100644
> index 000000000000..85f67308698d
> --- /dev/null
> +++ b/drivers/memory/rasf_common.c
> @@ -0,0 +1,269 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * rasf_common.c - Common functions for memory RASF driver
> + *
> + * Copyright (c) 2023 HiSilicon Limited.
> + *
> + * This driver implements call back functions for the scrub
> + * configure driver to configure the parameters of the hw patrol
> + * scrubbers in the system, which exposed via the ACPI RASF/RAS2
> + * table and PCC.
> + */
> +
> +#define pr_fmt(fmt) "MEMORY RASF COMMON: " fmt
> +
> +#include <linux/acpi.h>
> +#include <linux/io.h>
> +#include <linux/interrupt.h>
> +#include <linux/mailbox_controller.h>
> +#include <linux/mailbox_client.h>
> +#include <linux/module.h>
> +#include <linux/of.h>

of.h Shouldn't be here in an ACPI driver!

> +#include <linux/platform_device.h>
> +
> +#include <acpi/rasf_acpi.h>
> +#include <memory/rasf.h>
> +
> +static int enable_write(struct rasf_context *rasf_ctx, long val)
> +{
> + int ret;
> + bool enable = val;
> +
> + ret = rasf_ctx->ops->enable_scrub(rasf_ctx, enable);
> + if (ret) {
> + pr_err("enable patrol scrub fail, enable=%d ret=%d\n",
> + enable, ret);

dev_err(rasf_ctx->dev,...

> + return ret;
> + }
> +
> + return 0;
> +}

> +
> +/**
> + * rasf_hw_scrub_is_visible() - Callback to return attribute visibility
> + * @drv_data: Pointer to driver-private data structure passed
> + * as argument to devm_scrub_device_register().
> + * @attr_id: Scrub attribute
> + * @region_id: ID of the memory region
> + *
> + * Returns: 0 on success, an error otherwise
> + */
> +umode_t rasf_hw_scrub_is_visible(struct device *dev, u32 attr_id, int region_id)
> +{
> + switch (attr_id) {
> + case scrub_rate_available:
> + return 0444;
> + case scrub_enable:
> + case scrub_enable_background_scrub:
> + return 0200;
> + case scrub_addr_base:
> + case scrub_addr_size:
> + case scrub_rate:
> + return 0644;

As before, I'd prefer to see this passed the current permissions then just
return those rather than encoding them here and in the attributes where they
may end up out of sync

> + default:
> + return 0;
> + }
> +}

> +
> +/**
> + * rasf_hw_scrub_read_strings() - Read callback for string attributes
> + * @device: Pointer to scrub device
> + * @attr_id: Scrub attribute
> + * @region_id: ID of the memory region
> + * @buf: Pointer to the buffer for copying returned string
> + *
> + * Returns: 0 on success, an error otherwise
> + */
> +int rasf_hw_scrub_read_strings(struct device *device, u32 attr_id, int region_id,
> + char *buf)

dev maybe instead of device. Shorter lines and it's very common shorthand.

> +{
> + struct rasf_context *rasf_ctx;
> +
> + rasf_ctx = dev_get_drvdata(device);

struct rasf_context *rasf_ctx = dev_get_drvdata(dev);
Same throughout.
> +
> + switch (attr_id) {
> + case scrub_rate_available:
> + return rate_available_read(rasf_ctx, buf);
> + default:
> + return -ENOTSUPP;
> + }
> +}