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Date: Wed, 5 Jan 2022 15:46:38 -0800 (PST)
From: Ilkka Koskinen <ilkka@...amperecomputing.com>
To: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
cc: Ilkka Koskinen <ilkka@...amperecomputing.com>,
guohanjun@...wei.com, sudeep.holla@....com, rafael@...nel.org,
linux@...linux.org.uk, lenb@...nel.org, robert.moore@...el.com,
linux-acpi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org, patches@...erecomputing.com,
scott@...amperecomputing.com, darren@...amperecomputing.com,
james.morse@....com
Subject: Re: [PATCH v3 2/2] ACPI: AGDI: Add driver for Arm Generic Diagnostic
Dump and Reset device
Hi Lorenzo,
On Wed, 5 Jan 2022, Lorenzo Pieralisi wrote:
> [+James, for SDEI bits]
>
> On Thu, Dec 30, 2021 at 07:37:25PM -0800, Ilkka Koskinen wrote:
>> ACPI for Arm Components 1.1 Platform Design Document v1.1 [0] specifices
>> Arm Generic Diagnostic Device Interface (AGDI). It allows an admin to
>> issue diagnostic dump and reset via an SDEI event or an interrupt.
>> This patch implements SDEI path.
>>
>> [0] https://developer.arm.com/documentation/den0093/latest/
>>
>> Signed-off-by: Ilkka Koskinen <ilkka@...amperecomputing.com>
>> ---
>> drivers/acpi/arm64/Kconfig | 8 +++
>> drivers/acpi/arm64/Makefile | 1 +
>> drivers/acpi/arm64/agdi.c | 125 ++++++++++++++++++++++++++++++++++++
>> 3 files changed, 134 insertions(+)
>> create mode 100644 drivers/acpi/arm64/agdi.c
>>
>> diff --git a/drivers/acpi/arm64/Kconfig b/drivers/acpi/arm64/Kconfig
>> index 6dba187f4f2e..24869ba5b365 100644
>> --- a/drivers/acpi/arm64/Kconfig
>> +++ b/drivers/acpi/arm64/Kconfig
>> @@ -8,3 +8,11 @@ config ACPI_IORT
>>
>> config ACPI_GTDT
>> bool
>> +
>> +config ACPI_AGDI
>> + bool "Arm Generic Diagnostic Dump and Reset Device Interface"
>> + depends on ARM_SDE_INTERFACE
>> + help
>> + Arm Generic Diagnostic Dump and Reset Device Interface (AGDI) is
>> + a standard that enables issuing a non-maskable diagnostic dump and
>> + reset command.
>> diff --git a/drivers/acpi/arm64/Makefile b/drivers/acpi/arm64/Makefile
>> index 66acbe77f46e..7b9e4045659d 100644
>> --- a/drivers/acpi/arm64/Makefile
>> +++ b/drivers/acpi/arm64/Makefile
>> @@ -1,4 +1,5 @@
>> # SPDX-License-Identifier: GPL-2.0-only
>> +obj-$(CONFIG_ACPI_AGDI) += agdi.o
>> obj-$(CONFIG_ACPI_IORT) += iort.o
>> obj-$(CONFIG_ACPI_GTDT) += gtdt.o
>> obj-y += dma.o
>> diff --git a/drivers/acpi/arm64/agdi.c b/drivers/acpi/arm64/agdi.c
>> new file mode 100644
>> index 000000000000..6525ccbae5c1
>> --- /dev/null
>> +++ b/drivers/acpi/arm64/agdi.c
>> @@ -0,0 +1,125 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * This file implements handling of
>> + * Arm Generic Diagnostic Dump and Reset Interface table (AGDI)
>> + *
>> + * Copyright (c) 2021, Ampere Computing LLC
>> + */
>> +
>> +#define pr_fmt(fmt) "ACPI: AGDI: " fmt
>> +
>> +#include <linux/kernel.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/slab.h>
>> +#include <linux/module.h>
>> +#include <linux/kernel.h>
>> +#include <linux/acpi.h>
>> +#include <linux/arm_sdei.h>
>> +#include <linux/io.h>
>
> Nit: alphabetical order.
I clean them
>
>> +
>> +struct agdi_data {
>> + int sdei_event;
>> +};
>> +
>> +static int agdi_sdei_handler(u32 sdei_event, struct pt_regs *regs, void *arg)
>> +{
>> + nmi_panic(regs, "Arm Generic Diagnostic Dump and Reset SDEI event issued");
>> + return 0;
>> +}
>> +
>> +static int agdi_sdei_probe(struct platform_device *pdev,
>> + struct agdi_data *adata)
>> +{
>> + int err;
>> +
>> + err = sdei_event_register(adata->sdei_event, agdi_sdei_handler, pdev);
>> + if (err) {
>> + dev_err(&pdev->dev, "Failed to register for SDEI event %d",
>> + adata->sdei_event);
>> + return err;
>> + }
>> +
>> + err = sdei_event_enable(adata->sdei_event);
>> + if (err) {
>> + sdei_event_unregister(adata->sdei_event);
>> + dev_err(&pdev->dev, "Failed to enable event %d\n",
>> + adata->sdei_event);
>> + return err;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int agdi_probe(struct platform_device *pdev)
>> +{
>> + struct agdi_data *adata;
>> +
>> + adata = dev_get_platdata(&pdev->dev);
>> + if (!adata)
>> + return -EINVAL;
>> +
>> + return agdi_sdei_probe(pdev, adata);
>> +}
>> +
>> +static int agdi_remove(struct platform_device *pdev)
>> +{
>> + struct agdi_data *adata = platform_get_drvdata(pdev);
>> +
>> + sdei_event_disable(adata->sdei_event);
>> + sdei_event_unregister(adata->sdei_event);
>> +
>> + return 0;
>> +}
>> +
>> +static struct platform_driver agdi_driver = {
>> + .driver = {
>> + .name = "agdi",
>> + },
>> + .probe = agdi_probe,
>> + .remove = agdi_remove,
>> +};
>
> May I ask why we need a platform device (and driver) to register
> an SDEI event ?
Well, I guess I thought to have a device/driver to handle SDEI events and
interrupts since the spec calls it a device. I can certainly remove those,
if that's preferred.
>
>> +static int __init agdi_init(void)
>> +{
>> + int ret;
>> + acpi_status status;
>> + struct acpi_table_agdi *agdi_table;
>> + struct agdi_data pdata;
>> + struct platform_device *pdev;
>> +
>> + if (acpi_disabled)
>> + return 0;
>
> Why don't we call agdi_init() from acpi_init() as we do for IORT/VIOT ?
>
> I don't think it is necessary to add a device_initcall(), with related
> ordering dependencies.
That's a good point. I change it.
>
>> +
>> + status = acpi_get_table(ACPI_SIG_AGDI, 0,
>> + (struct acpi_table_header **) &agdi_table);
>> + if (ACPI_FAILURE(status))
>> + return -ENODEV;
>> +
>> + if (agdi_table->flags & ACPI_AGDI_SIGNALING_MODE) {
>
> Is this because specs need updating ?
Yes, that's the reason. AGDI table is missing flags that would define
trigger type and polarity.
>
>> + pr_warn("Interrupt signaling is not supported");
>> + ret = -ENODEV;
>> + goto err_put_table;
>> + }
>> +
>> + pdata.sdei_event = agdi_table->sdei_event;
>> +
>> + pdev = platform_device_register_data(NULL, "agdi", 0, &pdata, sizeof(pdata));
>> + if (IS_ERR(pdev)) {
>> + ret = PTR_ERR(pdev);
>> + goto err_put_table;
>> + }
>> +
>> + ret = platform_driver_register(&agdi_driver);
>> + if (ret)
>> + goto err_device_unregister;
>> +
>> + acpi_put_table((struct acpi_table_header *)agdi_table);
>> + return 0;
>> +
>> +err_device_unregister:
>> + platform_device_unregister(pdev);
>> +err_put_table:
>> + acpi_put_table((struct acpi_table_header *)agdi_table);
>> + return ret;
>> +}
>> +device_initcall(agdi_init);
>
> See above.
>
> Thanks,
> Lorenzo
>
Cheers, Ilkka
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