[PATCH v7 3/5] drivers: firmware: add riscv SSE support
Anup Patel
anup at brainfault.org
Sun Oct 5 22:38:17 PDT 2025
On Mon, Sep 8, 2025 at 11:50 PM Clément Léger <cleger at rivosinc.com> wrote:
>
> Add driver level interface to use RISC-V SSE arch support. This interface
> allows registering SSE handlers, and receive them. This will be used by
> PMU and GHES driver.
>
> Co-developed-by: Himanshu Chauhan <hchauhan at ventanamicro.com>
> Signed-off-by: Himanshu Chauhan <hchauhan at ventanamicro.com>
> Signed-off-by: Clément Léger <cleger at rivosinc.com>
> Acked-by: Conor Dooley <conor.dooley at microchip.com>
> ---
> MAINTAINERS | 15 +
> drivers/firmware/Kconfig | 1 +
> drivers/firmware/Makefile | 1 +
> drivers/firmware/riscv/Kconfig | 15 +
> drivers/firmware/riscv/Makefile | 3 +
> drivers/firmware/riscv/riscv_sbi_sse.c | 701 +++++++++++++++++++++++++
> include/linux/riscv_sbi_sse.h | 57 ++
> 7 files changed, 793 insertions(+)
> create mode 100644 drivers/firmware/riscv/Kconfig
> create mode 100644 drivers/firmware/riscv/Makefile
> create mode 100644 drivers/firmware/riscv/riscv_sbi_sse.c
> create mode 100644 include/linux/riscv_sbi_sse.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index fe168477caa4..684d23f852c3 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -21648,6 +21648,13 @@ T: git git://git.kernel.org/pub/scm/linux/kernel/git/iommu/linux.git
> F: Documentation/devicetree/bindings/iommu/riscv,iommu.yaml
> F: drivers/iommu/riscv/
>
> +RISC-V FIRMWARE DRIVERS
> +M: Conor Dooley <conor at kernel.org>
> +L: linux-riscv at lists.infradead.org
> +S: Maintained
> +T: git git://git.kernel.org/pub/scm/linux/kernel/git/conor/linux.git
> +F: drivers/firmware/riscv/*
> +
> RISC-V MICROCHIP FPGA SUPPORT
> M: Conor Dooley <conor.dooley at microchip.com>
> M: Daire McNamara <daire.mcnamara at microchip.com>
> @@ -21712,6 +21719,14 @@ F: arch/riscv/boot/dts/spacemit/
> N: spacemit
> K: spacemit
>
> +RISC-V SSE DRIVER
> +M: Clément Léger <cleger at rivosinc.com>
> +R: Himanshu Chauhan <himanshu at thechauhan.dev>
> +L: linux-riscv at lists.infradead.org
> +S: Maintained
> +F: drivers/firmware/riscv/riscv_sse.c
> +F: include/linux/riscv_sse.h
> +
> RISC-V THEAD SoC SUPPORT
> M: Drew Fustini <fustini at kernel.org>
> M: Guo Ren <guoren at kernel.org>
> diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
> index bbd2155d8483..1894df87b08e 100644
> --- a/drivers/firmware/Kconfig
> +++ b/drivers/firmware/Kconfig
> @@ -294,6 +294,7 @@ source "drivers/firmware/meson/Kconfig"
> source "drivers/firmware/microchip/Kconfig"
> source "drivers/firmware/psci/Kconfig"
> source "drivers/firmware/qcom/Kconfig"
> +source "drivers/firmware/riscv/Kconfig"
> source "drivers/firmware/samsung/Kconfig"
> source "drivers/firmware/smccc/Kconfig"
> source "drivers/firmware/tegra/Kconfig"
> diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
> index 4ddec2820c96..6cdd84570ea7 100644
> --- a/drivers/firmware/Makefile
> +++ b/drivers/firmware/Makefile
> @@ -34,6 +34,7 @@ obj-y += efi/
> obj-y += imx/
> obj-y += psci/
> obj-y += qcom/
> +obj-y += riscv/
> obj-y += samsung/
> obj-y += smccc/
> obj-y += tegra/
> diff --git a/drivers/firmware/riscv/Kconfig b/drivers/firmware/riscv/Kconfig
> new file mode 100644
> index 000000000000..ed5b663ac5f9
> --- /dev/null
> +++ b/drivers/firmware/riscv/Kconfig
> @@ -0,0 +1,15 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +menu "Risc-V Specific firmware drivers"
> +depends on RISCV
> +
> +config RISCV_SBI_SSE
> + bool "Enable SBI Supervisor Software Events support"
> + depends on RISCV_SBI
> + default y
> + help
> + The Supervisor Software Events support allows the SBI to deliver
> + NMI-like notifications to the supervisor mode software. When enabled,
> + this option provides support to register callbacks on specific SSE
> + events.
> +
> +endmenu
> diff --git a/drivers/firmware/riscv/Makefile b/drivers/firmware/riscv/Makefile
> new file mode 100644
> index 000000000000..c8795d4bbb2e
> --- /dev/null
> +++ b/drivers/firmware/riscv/Makefile
> @@ -0,0 +1,3 @@
> +# SPDX-License-Identifier: GPL-2.0
> +
> +obj-$(CONFIG_RISCV_SBI_SSE) += riscv_sbi_sse.o
> diff --git a/drivers/firmware/riscv/riscv_sbi_sse.c b/drivers/firmware/riscv/riscv_sbi_sse.c
> new file mode 100644
> index 000000000000..57b6dad92482
> --- /dev/null
> +++ b/drivers/firmware/riscv/riscv_sbi_sse.c
> @@ -0,0 +1,701 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2024 Rivos Inc.
> + */
> +
> +#define pr_fmt(fmt) "sse: " fmt
> +
> +#include <linux/cpu.h>
> +#include <linux/cpuhotplug.h>
> +#include <linux/cpu_pm.h>
> +#include <linux/hardirq.h>
> +#include <linux/list.h>
> +#include <linux/percpu-defs.h>
> +#include <linux/reboot.h>
> +#include <linux/riscv_sbi_sse.h>
> +#include <linux/slab.h>
> +
> +#include <asm/sbi.h>
> +#include <asm/sse.h>
> +
> +struct sse_event {
> + struct list_head list;
> + u32 evt_id;
> + u32 priority;
> + sse_event_handler_fn *handler;
> + void *handler_arg;
> + /* Only valid for global events */
> + unsigned int cpu;
> +
> + union {
> + struct sse_registered_event *global;
> + struct sse_registered_event __percpu *local;
> + };
> +};
> +
> +static int sse_hp_state;
> +static bool sse_available __ro_after_init;
> +static DEFINE_SPINLOCK(events_list_lock);
> +static LIST_HEAD(events);
> +static DEFINE_MUTEX(sse_mutex);
> +
> +struct sse_registered_event {
> + struct sse_event_arch_data arch;
> + struct sse_event *event;
> + unsigned long attr;
> + bool is_enabled;
> +};
> +
<snip>
> +
> +static int __init sse_init(void)
> +{
> + int ret;
> +
> + if (sbi_probe_extension(SBI_EXT_SSE) <= 0) {
> + pr_err("Missing SBI SSE extension\n");
We might have older firmware which implements an older
SBI spec version so we should not throw errors over here.
Please change this to pr_info().
Regards,
Anup
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