Re: [PATCH 4/6] platform/apple: Add new Apple Mac SMC driver

[Lee Jones <lee@kernel.org>]

On Thu, 01 Sep 2022, Russell King wrote:

> From: Hector Martin <marcan@marcan.st>
> 
> This driver implements support for the SMC (System Management
> Controller) in Apple Macs. In contrast to the existing applesmc driver,
> it uses pluggable backends that allow it to support different SMC
> implementations, and uses the MFD subsystem to expose the core SMC
> functionality so that specific features (gpio, hwmon, battery, etc.) can
> be implemented by separate drivers in their respective downstream
> subsystems.
> 
> The initial RTKit backend adds support for Apple Silicon Macs (M1 et
> al). We hope a backend for T2 Macs will be written in the future
> (since those are not supported by applesmc), and eventually an x86
> backend would allow us to fully deprecate applesmc in favor of this
> driver.
> 
> Signed-off-by: Hector Martin <marcan@marcan.st>
> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> ---
>  drivers/platform/Kconfig           |   2 +
>  drivers/platform/Makefile          |   1 +
>  drivers/platform/apple/Kconfig     |  49 ++++
>  drivers/platform/apple/Makefile    |  11 +
>  drivers/platform/apple/smc.h       |  28 ++
>  drivers/platform/apple/smc_core.c  | 249 ++++++++++++++++
>  drivers/platform/apple/smc_rtkit.c | 451 +++++++++++++++++++++++++++++
>  include/linux/mfd/macsmc.h         |  86 ++++++
>  8 files changed, 877 insertions(+)
>  create mode 100644 drivers/platform/apple/Kconfig
>  create mode 100644 drivers/platform/apple/Makefile
>  create mode 100644 drivers/platform/apple/smc.h
>  create mode 100644 drivers/platform/apple/smc_core.c
>  create mode 100644 drivers/platform/apple/smc_rtkit.c
>  create mode 100644 include/linux/mfd/macsmc.h
> 
> diff --git a/drivers/platform/Kconfig b/drivers/platform/Kconfig
> index b437847b6237..5f8b9bcdb830 100644
> --- a/drivers/platform/Kconfig
> +++ b/drivers/platform/Kconfig
> @@ -13,4 +13,6 @@ source "drivers/platform/olpc/Kconfig"
>  
>  source "drivers/platform/surface/Kconfig"
>  
> +source "drivers/platform/apple/Kconfig"
> +
>  source "drivers/platform/x86/Kconfig"
> diff --git a/drivers/platform/Makefile b/drivers/platform/Makefile
> index 4de08ef4ec9d..3e5d5039a28c 100644
> --- a/drivers/platform/Makefile
> +++ b/drivers/platform/Makefile
> @@ -10,3 +10,4 @@ obj-$(CONFIG_OLPC_EC)		+= olpc/
>  obj-$(CONFIG_GOLDFISH)		+= goldfish/
>  obj-$(CONFIG_CHROME_PLATFORMS)	+= chrome/
>  obj-$(CONFIG_SURFACE_PLATFORMS)	+= surface/
> +obj-$(CONFIG_APPLE_PLATFORMS)	+= apple/
> diff --git a/drivers/platform/apple/Kconfig b/drivers/platform/apple/Kconfig
> new file mode 100644
> index 000000000000..42525aa9fbbe
> --- /dev/null
> +++ b/drivers/platform/apple/Kconfig
> @@ -0,0 +1,49 @@
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Apple Platform-Specific Drivers
> +#
> +
> +menuconfig APPLE_PLATFORMS
> +	bool "Apple Mac Platform-Specific Device Drivers"
> +	default y
> +	help
> +	  Say Y here to get to see options for platform-specific device drivers
> +	  for Apple devices. This option alone does not add any kernel code.
> +
> +	  If you say N, all options in this submenu will be skipped and disabled.
> +
> +if APPLE_PLATFORMS
> +
> +config APPLE_SMC
> +	tristate "Apple SMC Driver"
> +	depends on ARCH_APPLE || COMPILE_TEST
> +	default ARCH_APPLE
> +	select MFD_CORE
> +	help
> +	  Build support for the Apple System Management Controller present in
> +	  Apple Macs. This driver currently supports the SMC in Apple Silicon
> +	  Macs. For x86 Macs, see the applesmc driver (SENSORS_APPLESMC).
> +
> +	  Say Y here if you have an Apple Silicon Mac.
> +
> +	  To compile this driver as a module, choose M here: the module will
> +	  be called macsmc.
> +
> +if APPLE_SMC
> +
> +config APPLE_SMC_RTKIT
> +	tristate "RTKit (Apple Silicon) backend"
> +	depends on ARCH_APPLE || COMPILE_TEST
> +	depends on APPLE_RTKIT
> +	default ARCH_APPLE
> +	help
> +	  Build support for SMC communications via the RTKit backend. This is
> +	  required for Apple Silicon Macs.
> +
> +	  Say Y here if you have an Apple Silicon Mac.
> +
> +	  To compile this driver as a module, choose M here: the module will
> +	  be called macsmc-rtkit.
> +
> +endif
> +endif
> diff --git a/drivers/platform/apple/Makefile b/drivers/platform/apple/Makefile
> new file mode 100644
> index 000000000000..79fac195398b
> --- /dev/null
> +++ b/drivers/platform/apple/Makefile
> @@ -0,0 +1,11 @@
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Makefile for linux/drivers/platform/apple
> +# Apple Platform-Specific Drivers
> +#
> +
> +macsmc-y				+= smc_core.o
> +macsmc-rtkit-y				+= smc_rtkit.o
> +
> +obj-$(CONFIG_APPLE_SMC)			+= macsmc.o
> +obj-$(CONFIG_APPLE_SMC_RTKIT)		+= macsmc-rtkit.o
> diff --git a/drivers/platform/apple/smc.h b/drivers/platform/apple/smc.h
> new file mode 100644
> index 000000000000..8ae51887b2c5
> --- /dev/null
> +++ b/drivers/platform/apple/smc.h
> @@ -0,0 +1,28 @@
> +// SPDX-License-Identifier: GPL-2.0-only OR MIT
> +/*
> + * Apple SMC internal core definitions
> + * Copyright (C) The Asahi Linux Contributors
> + */
> +
> +#ifndef _SMC_H
> +#define _SMC_H
> +
> +#include <linux/mfd/macsmc.h>
> +
> +struct apple_smc_backend_ops {
> +	int (*read_key)(void *cookie, smc_key key, void *buf, size_t size);
> +	int (*write_key)(void *cookie, smc_key key, void *buf, size_t size);
> +	int (*write_key_atomic)(void *cookie, smc_key key, void *buf, size_t size);
> +	int (*rw_key)(void *cookie, smc_key key, void *wbuf, size_t wsize,
> +		      void *rbuf, size_t rsize);
> +	int (*get_key_by_index)(void *cookie, int index, smc_key *key);
> +	int (*get_key_info)(void *cookie, smc_key key, struct apple_smc_key_info *info);
> +};
> +
> +struct apple_smc *apple_smc_probe(struct device *dev, const struct apple_smc_backend_ops *ops,
> +				  void *cookie);
> +void *apple_smc_get_cookie(struct apple_smc *smc);
> +int apple_smc_remove(struct apple_smc *smc);
> +void apple_smc_event_received(struct apple_smc *smc, uint32_t event);
> +
> +#endif
> diff --git a/drivers/platform/apple/smc_core.c b/drivers/platform/apple/smc_core.c
> new file mode 100644
> index 000000000000..daf029cd072f
> --- /dev/null
> +++ b/drivers/platform/apple/smc_core.c
> @@ -0,0 +1,249 @@
> +// SPDX-License-Identifier: GPL-2.0-only OR MIT
> +/*
> + * Apple SMC core framework
> + * Copyright The Asahi Linux Contributors
> + */
> +
> +#include <linux/device.h>
> +#include <linux/mfd/core.h>

Please refrain from using the MFD API outside of drivers/mfd.

If you need an MFD driver, please separate it out.

If not, please replace it with the platform_*() API instead.

Thanks.

-- 
Lee Jones [李琼斯]

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