Re: [PATCH v4 37/38] platform/x86: intel_pmc_ipc: Convert to MFD

Lee Jones
2020-01-22T12:34:44Z

On Tue, 21 Jan 2020, Mika Westerberg wrote:

> This driver only creates a bunch of platform devices sharing resources
> belonging to the PMC device. This is pretty much what MFD subsystem is
> for so move the driver there, renaming it to intel_pmc_bxt.c which
> should be more clear what it is.
>
> MFD subsystem provides nice helper APIs for subdevice creation so
> convert the driver to use those. Unfortunately the ACPI device includes
> separate resources for most of the subdevices so we cannot simply call
> mfd_add_devices() to create all of them but instead we need to call it
> separately for each device.
>
> The new MFD driver continues to expose two sysfs attributes that allow
> userspace to send IPC commands to the PMC/SCU to avoid breaking any
> existing applications that may use these. Generally this is bad idea so
> document this in the ABI documentation.
>
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> ---
> .../ABI/obsolete/sysfs-driver-intel_pmc_bxt | 22 +
> arch/x86/include/asm/intel_pmc_ipc.h | 47 --
> arch/x86/include/asm/intel_telemetry.h | 1 +
> drivers/mfd/Kconfig | 16 +-
> drivers/mfd/Makefile | 1 +
> drivers/mfd/intel_pmc_bxt.c | 496 ++++++++++++++
> drivers/platform/x86/Kconfig | 16 +-
> drivers/platform/x86/Makefile | 1 -
> drivers/platform/x86/intel_pmc_ipc.c | 645 ------------------
> .../platform/x86/intel_telemetry_debugfs.c | 12 +-
> drivers/platform/x86/intel_telemetry_pltdrv.c | 2 +
> drivers/usb/typec/tcpm/Kconfig | 2 +-
> include/linux/mfd/intel_pmc_bxt.h | 21 +
> 13 files changed, 572 insertions(+), 710 deletions(-)
> create mode 100644 Documentation/ABI/obsolete/sysfs-driver-intel_pmc_bxt
> delete mode 100644 arch/x86/include/asm/intel_pmc_ipc.h
> create mode 100644 drivers/mfd/intel_pmc_bxt.c
> delete mode 100644 drivers/platform/x86/intel_pmc_ipc.c
> create mode 100644 include/linux/mfd/intel_pmc_bxt.h

[...]

> +static int intel_pmc_probe(struct platform_device *pdev)
> +{
> + struct intel_scu_ipc_pdata pdata = {};
> + struct intel_pmc_dev *pmc;
> + int ret;
> +
> + pmc = devm_kzalloc(&pdev->dev, sizeof(*pmc), GFP_KERNEL);
> + if (!pmc)
> + return -ENOMEM;
> +
> + pmc->dev = &pdev->dev;
> + spin_lock_init(&pmc->gcr_lock);
> +
> + ret = intel_pmc_get_resources(pdev, pmc, &pdata);
> + if (ret) {
> + dev_err(&pdev->dev, "Failed to request resources\n");
> + return ret;
> + }
> +
> + pmc->scu = devm_intel_scu_ipc_register(&pdev->dev, &pdata);
> + if (IS_ERR(pmc->scu))
> + return PTR_ERR(pmc->scu);

*_register is better than *_probe. If it was called that (or maybe
*_init) initially I may have missed the issue altogether ...

However, I still think it the SCU IPC *device* needs to be a device
driver and abide by the rules, ensuring it uses the device driver
model/API. As such, it should be registered and probed as a device.

If you require something from it you should call into it (perhaps
using a register function like above), but that should be done *after*
the device has been bound and probed.

> + platform_set_drvdata(pdev, pmc);
> +
> + ret = intel_pmc_create_devices(pmc);
> + if (ret)
> + dev_err(&pdev->dev, "Failed to create PMC devices\n");
> +
> + return ret;
> +}

--
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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