Add driver to parse the ACPI RISC-V Quality of Service Controller (RQSC)
table which describes the capacity and bandwidth QoS controllers in a
system. The QoS controllers implement the RISC-V Capacity and Bandwidth
Controller QoS Register Interface (CBQRI) specification.
Link: https://github.com/riscv-non-isa/riscv-cbqri/releases/tag/v1.0
Link: https://github.com/riscv-non-isa/riscv-rqsc/blob/main/src/
Signed-off-by: Drew Fustini <fustini@kernel.org>
---
MAINTAINERS | 1 +
arch/riscv/include/asm/acpi.h | 10 ++++
drivers/acpi/riscv/Makefile | 2 +-
drivers/acpi/riscv/rqsc.c | 112 ++++++++++++++++++++++++++++++++++++++++++
4 files changed, 124 insertions(+), 1 deletion(-)
diff --git a/MAINTAINERS b/MAINTAINERS
index 96ead357a634..e96a83dc9a02 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -22512,6 +22512,7 @@ S: Supported
F: arch/riscv/include/asm/qos.h
F: arch/riscv/include/asm/resctrl.h
F: arch/riscv/kernel/qos/
+F: drivers/acpi/riscv/rqsc.c
F: include/linux/riscv_qos.h
RISC-V RPMI AND MPXY DRIVERS
diff --git a/arch/riscv/include/asm/acpi.h b/arch/riscv/include/asm/acpi.h
index 6e13695120bc..16c6e25eed1e 100644
--- a/arch/riscv/include/asm/acpi.h
+++ b/arch/riscv/include/asm/acpi.h
@@ -71,6 +71,16 @@ int acpi_get_riscv_isa(struct acpi_table_header *table,
void acpi_get_cbo_block_size(struct acpi_table_header *table, u32 *cbom_size,
u32 *cboz_size, u32 *cbop_size);
+
+#ifdef CONFIG_RISCV_ISA_SSQOSID
+int acpi_parse_rqsc(struct acpi_table_header *table);
+#else
+static inline int acpi_parse_rqsc(struct acpi_table_header *table)
+{
+ return -EINVAL;
+}
+#endif /* CONFIG_RISCV_ISA_SSQOSID */
+
#else
static inline void acpi_init_rintc_map(void) { }
static inline struct acpi_madt_rintc *acpi_cpu_get_madt_rintc(int cpu)
diff --git a/drivers/acpi/riscv/Makefile b/drivers/acpi/riscv/Makefile
index 1284a076fa88..cf0f38c93a9f 100644
--- a/drivers/acpi/riscv/Makefile
+++ b/drivers/acpi/riscv/Makefile
@@ -1,5 +1,5 @@
# SPDX-License-Identifier: GPL-2.0-only
-obj-y += rhct.o init.o irq.o
+obj-y += rhct.o rqsc.o init.o irq.o
obj-$(CONFIG_ACPI_PROCESSOR_IDLE) += cpuidle.o
obj-$(CONFIG_ACPI_CPPC_LIB) += cppc.o
obj-$(CONFIG_ACPI_RIMT) += rimt.o
diff --git a/drivers/acpi/riscv/rqsc.c b/drivers/acpi/riscv/rqsc.c
new file mode 100644
index 000000000000..a86ddb39fae4
--- /dev/null
+++ b/drivers/acpi/riscv/rqsc.c
@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2025 Tenstorrent
+ * Author: Drew Fustini <fustini@kernel.org>
+ *
+ */
+
+#define pr_fmt(fmt) "ACPI: RQSC: " fmt
+
+#include <linux/acpi.h>
+#include <linux/bits.h>
+#include <linux/riscv_qos.h>
+
+#ifdef CONFIG_RISCV_ISA_SSQOSID
+
+#define CBQRI_CTRL_SIZE 0x1000
+
+static struct acpi_table_rqsc *acpi_get_rqsc(void)
+{
+ static struct acpi_table_header *rqsc;
+ acpi_status status;
+
+ /*
+ * RQSC will be used at runtime on every CPU, so we
+ * don't need to call acpi_put_table() to release the table mapping.
+ */
+ if (!rqsc) {
+ status = acpi_get_table(ACPI_SIG_RQSC, 0, &rqsc);
+ if (ACPI_FAILURE(status)) {
+ pr_warn_once("No RQSC table found\n");
+ return NULL;
+ }
+ }
+
+ return (struct acpi_table_rqsc *)rqsc;
+}
+
+int acpi_parse_rqsc(struct acpi_table_header *table)
+{
+ struct acpi_table_rqsc *rqsc;
+ int err;
+
+ BUG_ON(acpi_disabled);
+ if (!table) {
+ rqsc = acpi_get_rqsc();
+ if (!rqsc)
+ return -ENOENT;
+ } else {
+ rqsc = (struct acpi_table_rqsc *)table;
+ }
+
+ for (int i = 0; i < rqsc->num; i++) {
+ struct cbqri_controller_info *ctrl_info;
+
+ ctrl_info = kzalloc(sizeof(*ctrl_info), GFP_KERNEL);
+ if (!ctrl_info)
+ return -ENOMEM;
+
+ ctrl_info->type = rqsc->f[i].type;
+ ctrl_info->addr = rqsc->f[i].reg[1];
+ ctrl_info->size = CBQRI_CTRL_SIZE;
+ ctrl_info->rcid_count = rqsc->f[i].rcid;
+ ctrl_info->mcid_count = rqsc->f[i].mcid;
+
+ pr_info("Found controller with type %u addr 0x%lx size %lu rcid %u mcid %u",
+ ctrl_info->type, ctrl_info->addr, ctrl_info->size,
+ ctrl_info->rcid_count, ctrl_info->mcid_count);
+
+ if (ctrl_info->type == CBQRI_CONTROLLER_TYPE_CAPACITY) {
+ ctrl_info->cache.cache_id = rqsc->f[i].res.id1;
+ ctrl_info->cache.cache_level =
+ find_acpi_cache_level_from_id(ctrl_info->cache.cache_id);
+
+ struct acpi_pptt_cache *cache;
+
+ cache = find_acpi_cache_from_id(ctrl_info->cache.cache_id);
+ if (cache) {
+ ctrl_info->cache.cache_size = cache->size;
+ } else {
+ pr_warn("%s(): failed to determine size for cache id 0x%x",
+ __func__, ctrl_info->cache.cache_id);
+ ctrl_info->cache.cache_size = 0;
+ }
+
+ pr_info("Cache controller has ID 0x%x level %u size %u ",
+ ctrl_info->cache.cache_id, ctrl_info->cache.cache_level,
+ ctrl_info->cache.cache_size);
+
+ /*
+ * For CBQRI, any cpu (technically a hart in RISC-V terms)
+ * can access the memory-mapped registers of any CBQRI
+ * controller in the system.
+ */
+ err = cpumask_parse("FF", &ctrl_info->cache.cpu_mask);
+ if (err)
+ pr_err("Failed to convert cores mask string to cpumask (%d)", err);
+
+ } else if (ctrl_info->type == CBQRI_CONTROLLER_TYPE_BANDWIDTH) {
+ ctrl_info->mem.prox_dom = rqsc->f[i].res.id1;
+ pr_info("Memory controller with proximity domain %u",
+ ctrl_info->mem.prox_dom);
+ }
+
+ /* Fill the list shared with RISC-V QoS resctrl */
+ INIT_LIST_HEAD(&ctrl_info->list);
+ list_add_tail(&ctrl_info->list, &cbqri_controllers);
+ }
+
+ return 0;
+}
+
+#endif /* CONFIG_RISCV_ISA_SSQOSID */
--
2.43.0Hi Drew,
On Thu, Jan 29, 2026 at 4:28 AM Drew Fustini <fustini@kernel.org> wrote:
>
> Add driver to parse the ACPI RISC-V Quality of Service Controller (RQSC)
> table which describes the capacity and bandwidth QoS controllers in a
> system. The QoS controllers implement the RISC-V Capacity and Bandwidth
> Controller QoS Register Interface (CBQRI) specification.
>
> Link: https://github.com/riscv-non-isa/riscv-cbqri/releases/tag/v1.0
> Link: https://github.com/riscv-non-isa/riscv-rqsc/blob/main/src/
> Signed-off-by: Drew Fustini <fustini@kernel.org>
> ---
> MAINTAINERS | 1 +
> arch/riscv/include/asm/acpi.h | 10 ++++
> drivers/acpi/riscv/Makefile | 2 +-
> drivers/acpi/riscv/rqsc.c | 112 ++++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 124 insertions(+), 1 deletion(-)
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 96ead357a634..e96a83dc9a02 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -22512,6 +22512,7 @@ S: Supported
> F: arch/riscv/include/asm/qos.h
> F: arch/riscv/include/asm/resctrl.h
> F: arch/riscv/kernel/qos/
> +F: drivers/acpi/riscv/rqsc.c
> F: include/linux/riscv_qos.h
>
> RISC-V RPMI AND MPXY DRIVERS
> diff --git a/arch/riscv/include/asm/acpi.h b/arch/riscv/include/asm/acpi.h
> index 6e13695120bc..16c6e25eed1e 100644
> --- a/arch/riscv/include/asm/acpi.h
> +++ b/arch/riscv/include/asm/acpi.h
> @@ -71,6 +71,16 @@ int acpi_get_riscv_isa(struct acpi_table_header *table,
>
> void acpi_get_cbo_block_size(struct acpi_table_header *table, u32 *cbom_size,
> u32 *cboz_size, u32 *cbop_size);
> +
> +#ifdef CONFIG_RISCV_ISA_SSQOSID
> +int acpi_parse_rqsc(struct acpi_table_header *table);
> +#else
> +static inline int acpi_parse_rqsc(struct acpi_table_header *table)
> +{
> + return -EINVAL;
> +}
> +#endif /* CONFIG_RISCV_ISA_SSQOSID */
> +
> #else
> static inline void acpi_init_rintc_map(void) { }
> static inline struct acpi_madt_rintc *acpi_cpu_get_madt_rintc(int cpu)
> diff --git a/drivers/acpi/riscv/Makefile b/drivers/acpi/riscv/Makefile
> index 1284a076fa88..cf0f38c93a9f 100644
> --- a/drivers/acpi/riscv/Makefile
> +++ b/drivers/acpi/riscv/Makefile
> @@ -1,5 +1,5 @@
> # SPDX-License-Identifier: GPL-2.0-only
> -obj-y += rhct.o init.o irq.o
> +obj-y += rhct.o rqsc.o init.o irq.o
> obj-$(CONFIG_ACPI_PROCESSOR_IDLE) += cpuidle.o
> obj-$(CONFIG_ACPI_CPPC_LIB) += cppc.o
> obj-$(CONFIG_ACPI_RIMT) += rimt.o
> diff --git a/drivers/acpi/riscv/rqsc.c b/drivers/acpi/riscv/rqsc.c
> new file mode 100644
> index 000000000000..a86ddb39fae4
> --- /dev/null
> +++ b/drivers/acpi/riscv/rqsc.c
> @@ -0,0 +1,112 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2025 Tenstorrent
> + * Author: Drew Fustini <fustini@kernel.org>
> + *
> + */
> +
> +#define pr_fmt(fmt) "ACPI: RQSC: " fmt
> +
> +#include <linux/acpi.h>
> +#include <linux/bits.h>
> +#include <linux/riscv_qos.h>
> +
> +#ifdef CONFIG_RISCV_ISA_SSQOSID
> +
> +#define CBQRI_CTRL_SIZE 0x1000
> +
> +static struct acpi_table_rqsc *acpi_get_rqsc(void)
> +{
> + static struct acpi_table_header *rqsc;
> + acpi_status status;
> +
> + /*
> + * RQSC will be used at runtime on every CPU, so we
> + * don't need to call acpi_put_table() to release the table mapping.
> + */
> + if (!rqsc) {
> + status = acpi_get_table(ACPI_SIG_RQSC, 0, &rqsc);
> + if (ACPI_FAILURE(status)) {
> + pr_warn_once("No RQSC table found\n");
> + return NULL;
> + }
> + }
> +
> + return (struct acpi_table_rqsc *)rqsc;
> +}
> +
> +int acpi_parse_rqsc(struct acpi_table_header *table)
> +{
> + struct acpi_table_rqsc *rqsc;
> + int err;
> +
> + BUG_ON(acpi_disabled);
> + if (!table) {
> + rqsc = acpi_get_rqsc();
> + if (!rqsc)
> + return -ENOENT;
> + } else {
> + rqsc = (struct acpi_table_rqsc *)table;
> + }
> +
> + for (int i = 0; i < rqsc->num; i++) {
> + struct cbqri_controller_info *ctrl_info;
> +
> + ctrl_info = kzalloc(sizeof(*ctrl_info), GFP_KERNEL);
> + if (!ctrl_info)
> + return -ENOMEM;
> +
> + ctrl_info->type = rqsc->f[i].type;
> + ctrl_info->addr = rqsc->f[i].reg[1];
> + ctrl_info->size = CBQRI_CTRL_SIZE;
> + ctrl_info->rcid_count = rqsc->f[i].rcid;
> + ctrl_info->mcid_count = rqsc->f[i].mcid;
> +
> + pr_info("Found controller with type %u addr 0x%lx size %lu rcid %u mcid %u",
> + ctrl_info->type, ctrl_info->addr, ctrl_info->size,
> + ctrl_info->rcid_count, ctrl_info->mcid_count);
> +
> + if (ctrl_info->type == CBQRI_CONTROLLER_TYPE_CAPACITY) {
> + ctrl_info->cache.cache_id = rqsc->f[i].res.id1;
> + ctrl_info->cache.cache_level =
> + find_acpi_cache_level_from_id(ctrl_info->cache.cache_id);
> +
> + struct acpi_pptt_cache *cache;
> +
> + cache = find_acpi_cache_from_id(ctrl_info->cache.cache_id);
> + if (cache) {
> + ctrl_info->cache.cache_size = cache->size;
> + } else {
> + pr_warn("%s(): failed to determine size for cache id 0x%x",
> + __func__, ctrl_info->cache.cache_id);
> + ctrl_info->cache.cache_size = 0;
> + }
> +
> + pr_info("Cache controller has ID 0x%x level %u size %u ",
> + ctrl_info->cache.cache_id, ctrl_info->cache.cache_level,
> + ctrl_info->cache.cache_size);
> +
> + /*
> + * For CBQRI, any cpu (technically a hart in RISC-V terms)
> + * can access the memory-mapped registers of any CBQRI
> + * controller in the system.
> + */
> + err = cpumask_parse("FF", &ctrl_info->cache.cpu_mask);
Hardcode? acpi_pptt_get_cpumask_from_cache_id(ctrl_info->cache.cache_id,
&ctrl_info->cache.cpu_mask); ?
> + if (err)
> + pr_err("Failed to convert cores mask string to cpumask (%d)", err);
> +
> + } else if (ctrl_info->type == CBQRI_CONTROLLER_TYPE_BANDWIDTH) {
> + ctrl_info->mem.prox_dom = rqsc->f[i].res.id1;
> + pr_info("Memory controller with proximity domain %u",
> + ctrl_info->mem.prox_dom);
> + }
> +
> + /* Fill the list shared with RISC-V QoS resctrl */
> + INIT_LIST_HEAD(&ctrl_info->list);
> + list_add_tail(&ctrl_info->list, &cbqri_controllers);
> + }
> +
> + return 0;
> +}
> +
> +#endif /* CONFIG_RISCV_ISA_SSQOSID */
>
> --
> 2.43.0
>
Thanks,
Yunhui
On Mon, Feb 02, 2026 at 07:08:48PM +0800, yunhui cui wrote:
> Hi Drew,
>
> On Thu, Jan 29, 2026 at 4:28 AM Drew Fustini <fustini@kernel.org> wrote:
> >
> > Add driver to parse the ACPI RISC-V Quality of Service Controller (RQSC)
> > table which describes the capacity and bandwidth QoS controllers in a
> > system. The QoS controllers implement the RISC-V Capacity and Bandwidth
> > Controller QoS Register Interface (CBQRI) specification.
> >
> > Link: https://github.com/riscv-non-isa/riscv-cbqri/releases/tag/v1.0
> > Link: https://github.com/riscv-non-isa/riscv-rqsc/blob/main/src/
> > Signed-off-by: Drew Fustini <fustini@kernel.org>
> > ---
> > MAINTAINERS | 1 +
> > arch/riscv/include/asm/acpi.h | 10 ++++
> > drivers/acpi/riscv/Makefile | 2 +-
> > drivers/acpi/riscv/rqsc.c | 112 ++++++++++++++++++++++++++++++++++++++++++
> > 4 files changed, 124 insertions(+), 1 deletion(-)
> >
[..]
> > +int acpi_parse_rqsc(struct acpi_table_header *table)
> > +{
> > + struct acpi_table_rqsc *rqsc;
> > + int err;
> > +
> > + BUG_ON(acpi_disabled);
> > + if (!table) {
> > + rqsc = acpi_get_rqsc();
> > + if (!rqsc)
> > + return -ENOENT;
> > + } else {
> > + rqsc = (struct acpi_table_rqsc *)table;
> > + }
> > +
> > + for (int i = 0; i < rqsc->num; i++) {
> > + struct cbqri_controller_info *ctrl_info;
> > +
> > + ctrl_info = kzalloc(sizeof(*ctrl_info), GFP_KERNEL);
> > + if (!ctrl_info)
> > + return -ENOMEM;
> > +
> > + ctrl_info->type = rqsc->f[i].type;
> > + ctrl_info->addr = rqsc->f[i].reg[1];
> > + ctrl_info->size = CBQRI_CTRL_SIZE;
> > + ctrl_info->rcid_count = rqsc->f[i].rcid;
> > + ctrl_info->mcid_count = rqsc->f[i].mcid;
> > +
> > + pr_info("Found controller with type %u addr 0x%lx size %lu rcid %u mcid %u",
> > + ctrl_info->type, ctrl_info->addr, ctrl_info->size,
> > + ctrl_info->rcid_count, ctrl_info->mcid_count);
> > +
> > + if (ctrl_info->type == CBQRI_CONTROLLER_TYPE_CAPACITY) {
> > + ctrl_info->cache.cache_id = rqsc->f[i].res.id1;
> > + ctrl_info->cache.cache_level =
> > + find_acpi_cache_level_from_id(ctrl_info->cache.cache_id);
> > +
> > + struct acpi_pptt_cache *cache;
> > +
> > + cache = find_acpi_cache_from_id(ctrl_info->cache.cache_id);
> > + if (cache) {
> > + ctrl_info->cache.cache_size = cache->size;
> > + } else {
> > + pr_warn("%s(): failed to determine size for cache id 0x%x",
> > + __func__, ctrl_info->cache.cache_id);
> > + ctrl_info->cache.cache_size = 0;
> > + }
> > +
> > + pr_info("Cache controller has ID 0x%x level %u size %u ",
> > + ctrl_info->cache.cache_id, ctrl_info->cache.cache_level,
> > + ctrl_info->cache.cache_size);
> > +
> > + /*
> > + * For CBQRI, any cpu (technically a hart in RISC-V terms)
> > + * can access the memory-mapped registers of any CBQRI
> > + * controller in the system.
> > + */
> > + err = cpumask_parse("FF", &ctrl_info->cache.cpu_mask);
>
> Hardcode? acpi_pptt_get_cpumask_from_cache_id(ctrl_info->cache.cache_id,
> &ctrl_info->cache.cpu_mask); ?
Thanks, I will give that a try as the current value 0xFF is not flexible.
Drew
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