Re: [PATCH v2 01/15] Revert "dm: SMEM (Shared memory) uclass"

[Sumit Garg <sumit.garg@kernel.org>]

On Mon, May 04, 2026 at 08:57:29PM +0200, Casey Connolly wrote:
> SMEM is a highly Qualcomm specific interface, while having a dedicated
> UCLASS for it offers a nice abstraction, for things like memory layout
> parsing we need to use it before the driver model is available.
> 
> Therefore, it doesn't make sense to fit SMEM into the driver model.
> Instead let's adopt a model closer to Linux, and parse SMEM really early
> during boot (as soon as we have the FDT).
> 
> This reverts commit 7b384eccc785b596f68448b155cbda26df57fb23.
> 
> Signed-off-by: Casey Connolly <casey.connolly@linaro.org>
> ---
>  arch/arm/Kconfig           |  1 -
>  drivers/Kconfig            |  2 --
>  drivers/Makefile           |  1 -
>  drivers/smem/Kconfig       | 25 -------------
>  drivers/smem/Makefile      |  7 ----
>  drivers/smem/smem-uclass.c | 46 ------------------------
>  include/dm/uclass-id.h     |  1 -
>  include/smem.h             | 90 ----------------------------------------------
>  8 files changed, 173 deletions(-)

Reviewed-by: Sumit Garg <sumit.garg@oss.qualcomm.com>

-Sumit

> 
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index f624675eadf8..dadb18e0b8cd 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -1141,9 +1141,8 @@ config ARCH_SNAPDRAGON
>  	select POWER_DOMAIN
>  	select GPIO_EXTRA_HEADER
>  	select MSM_SMEM
>  	select OF_CONTROL
> -	select SMEM
>  	select SPMI
>  	select BOARD_LATE_INIT
>  	select OF_BOARD
>  	select SAVE_PREV_BL_FDT_ADDR if !ENABLE_ARM_SOC_BOOT0_HOOK
> diff --git a/drivers/Kconfig b/drivers/Kconfig
> index 47606ddc6c8b..aa293df37c57 100644
> --- a/drivers/Kconfig
> +++ b/drivers/Kconfig
> @@ -123,10 +123,8 @@ source "drivers/scsi/Kconfig"
>  source "drivers/serial/Kconfig"
>  
>  source "drivers/sm/Kconfig"
>  
> -source "drivers/smem/Kconfig"
> -
>  source "drivers/sound/Kconfig"
>  
>  source "drivers/soc/Kconfig"
>  
> diff --git a/drivers/Makefile b/drivers/Makefile
> index 43d0ba332818..ca3e87ffb102 100644
> --- a/drivers/Makefile
> +++ b/drivers/Makefile
> @@ -118,9 +118,8 @@ obj-y += pwm/
>  obj-y += reset/
>  obj-y += input/
>  obj-y += iommu/
>  # SOC specific infrastructure drivers.
> -obj-y += smem/
>  obj-y += thermal/
>  obj-$(CONFIG_TEE) += tee/
>  obj-$(CONFIG_ARM_FFA_TRANSPORT) += firmware/arm-ffa/
>  obj-y += axi/
> diff --git a/drivers/smem/Kconfig b/drivers/smem/Kconfig
> deleted file mode 100644
> index e5d7dcc81b17..000000000000
> --- a/drivers/smem/Kconfig
> +++ /dev/null
> @@ -1,25 +0,0 @@
> -menuconfig SMEM
> -	bool  "SMEM (Shared Memory mamanger) support"
> -
> -if SMEM
> -
> -config SANDBOX_SMEM
> -    bool "Sandbox Shared Memory Manager (SMEM)"
> -    depends on SANDBOX && DM
> -    help
> -      enable SMEM support for sandbox. This is an emulation of a real SMEM
> -      manager.
> -      The sandbox driver allocates a shared memory from the heap and
> -      initialzies it on start.
> -
> -config MSM_SMEM
> -    bool "Qualcomm Shared Memory Manager (SMEM)"
> -    depends on DM
> -    depends on ARCH_SNAPDRAGON || ARCH_IPQ40XX
> -    select DEVRES
> -    help
> -      Enable support for the Qualcomm Shared Memory Manager.
> -      The driver provides an interface to items in a heap shared among all
> -      processors in a Qualcomm platform.
> -
> -endif # menu "SMEM Support"
> diff --git a/drivers/smem/Makefile b/drivers/smem/Makefile
> deleted file mode 100644
> index af3e9b50883c..000000000000
> --- a/drivers/smem/Makefile
> +++ /dev/null
> @@ -1,7 +0,0 @@
> -# SPDX-License-Identifier: GPL-2.0+
> -#
> -# Makefile for the U-Boot SMEM interface drivers
> -
> -obj-$(CONFIG_SANDBOX_SMEM) += sandbox_smem.o
> -obj-$(CONFIG_SMEM) += smem-uclass.o
> -obj-$(CONFIG_MSM_SMEM) += msm_smem.o
> diff --git a/drivers/smem/smem-uclass.c b/drivers/smem/smem-uclass.c
> deleted file mode 100644
> index 4dea5cc4bf1c..000000000000
> --- a/drivers/smem/smem-uclass.c
> +++ /dev/null
> @@ -1,46 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0+
> -/*
> - * Copyright (c) 2018 Ramon Fried <ramon.fried@gmail.com>
> - */
> -
> -#define LOG_CATEGORY UCLASS_SMEM
> -
> -#include <dm.h>
> -#include <smem.h>
> -
> -int smem_alloc(struct udevice *dev, unsigned int host,
> -		unsigned int item, size_t size)
> -{
> -	struct smem_ops *ops = smem_get_ops(dev);
> -
> -	if (!ops->alloc)
> -		return -ENOSYS;
> -
> -	return ops->alloc(host, item, size);
> -}
> -
> -void *smem_get(struct udevice *dev, unsigned int host,
> -		unsigned int item, size_t *size)
> -{
> -	struct smem_ops *ops = smem_get_ops(dev);
> -
> -	if (!ops->get)
> -		return NULL;
> -
> -	return ops->get(host, item, size);
> -}
> -
> -int smem_get_free_space(struct udevice *dev, unsigned int host)
> -{
> -	struct smem_ops *ops = smem_get_ops(dev);
> -
> -	if (!ops->get_free_space)
> -		return -ENOSYS;
> -
> -	return ops->get_free_space(host);
> -}
> -
> -UCLASS_DRIVER(smem) = {
> -	.id     = UCLASS_SMEM,
> -	.name       = "smem",
> -};
> diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
> index 36b5d87c304f..fe0aae2720ca 100644
> --- a/include/dm/uclass-id.h
> +++ b/include/dm/uclass-id.h
> @@ -133,9 +133,8 @@ enum uclass_id {
>  	UCLASS_SCMI_BASE,	/* Interface for SCMI Base protocol */
>  	UCLASS_SCSI,		/* SCSI device */
>  	UCLASS_SERIAL,		/* Serial UART */
>  	UCLASS_SIMPLE_BUS,	/* Bus with child devices */
> -	UCLASS_SMEM,		/* Shared memory interface */
>  	UCLASS_SOC,		/* SOC Device */
>  	UCLASS_SOUND,		/* Playing simple sounds */
>  	UCLASS_SPI,		/* SPI bus */
>  	UCLASS_SPI_FLASH,	/* SPI flash */
> diff --git a/include/smem.h b/include/smem.h
> deleted file mode 100644
> index b19c534ebc43..000000000000
> --- a/include/smem.h
> +++ /dev/null
> @@ -1,90 +0,0 @@
> -/* SPDX-License-Identifier: GPL-2.0+ */
> -/*
> - * The shared memory system is an allocate-only heap structure that
> - * consists of one of more memory areas that can be accessed by the processors
> - * in the SoC.
> - *
> - * Allocation can be done globally for all processors or to an individual processor.
> - * This is controlled by the @host parameter.
> - *
> - * Allocation and management of heap can be implemented in various ways,
> - * The @item parameter should be used as an index/hash to the memory region.
> - *
> - * Copyright (c) 2018 Ramon Fried <ramon.fried@gmail.com>
> - */
> -
> -#ifndef _smemh_
> -#define _smemh_
> -
> -/* struct smem_ops: Operations for the SMEM uclass */
> -struct smem_ops {
> -	/**
> -	 * alloc() - allocate space for a smem item
> -	 *
> -	 * @host:	remote processor id, or -1 for all processors.
> -	 * @item:	smem item handle
> -	 * @size:	number of bytes to be allocated
> -	 * @return 0 if OK, -ve on error
> -	 */
> -	int (*alloc)(unsigned int host,
> -		unsigned int item, size_t size);
> -
> -	/**
> -	 * get() - Resolve ptr of size of a smem item
> -	 *
> -	 * @host:	the remote processor, of -1 for all processors.
> -	 * @item:	smem item handle
> -	 * @size:	pointer to be filled out with the size of the item
> -	 * @return	pointer on success, NULL on error
> -	 */
> -	void *(*get)(unsigned int host,
> -		unsigned int item, size_t *size);
> -
> -	/**
> -	 * get_free_space() - Get free space in smem in bytes
> -	 *
> -	 * @host:   the remote processor identifying a partition, or -1
> -	 *			for all processors.
> -	 * @return	free space, -ve on error
> -	 */
> -	int (*get_free_space)(unsigned int host);
> -};
> -
> -#define smem_get_ops(dev)	((struct smem_ops *)(dev)->driver->ops)
> -
> -/**
> - * smem_alloc() - allocate space for a smem item
> - * @host:	remote processor id, or -1
> - * @item:	smem item handle
> - * @size:	number of bytes to be allocated
> - * Return: 0 if OK, -ve on error
> - *
> - * Allocate space for a given smem item of size @size, given that the item is
> - * not yet allocated.
> - */
> -int smem_alloc(struct udevice *dev, unsigned int host, unsigned int item, size_t size);
> -
> -/**
> - * smem_get() - resolve ptr of size of a smem item
> - * @host:	the remote processor, or -1 for all processors.
> - * @item:	smem item handle
> - * @size:	pointer to be filled out with size of the item
> - * Return:	pointer on success, NULL on error
> - *
> - * Looks up smem item and returns pointer to it. Size of smem
> - * item is returned in @size.
> - */
> -void *smem_get(struct udevice *dev, unsigned int host, unsigned int item, size_t *size);
> -
> -/**
> - * smem_get_free_space() - retrieve amount of free space in a partition
> - * @host:	the remote processor identifying a partition, or -1
> - *			for all processors.
> - * Return:	size in bytes, -ve on error
> - *
> - * To be used by smem clients as a quick way to determine if any new
> - * allocations has been made.
> - */
> -int smem_get_free_space(struct udevice *dev, unsigned int host);
> -
> -#endif /* _smem_h_ */
> 
> -- 
> 2.53.0
>