CXL spec v3.0 9.17.3 CXL Root Device Specific Methods (_DSM) Add support to retrieve QTG ID via ACPI _DSM call. The _DSM call requires an input of an ACPI package with 4 dwords (read latency, write latency, read bandwidth, write bandwidth). The call returns a package with 1 WORD that provides the max supported QTG ID and a package that may contain 0 or more WORDs as the recommended QTG IDs in the recommended order. Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx> --- drivers/cxl/core/Makefile | 1 drivers/cxl/core/acpi.c | 99 +++++++++++++++++++++++++++++++++++++++++++++ drivers/cxl/cxl.h | 15 +++++++ 3 files changed, 115 insertions(+) create mode 100644 drivers/cxl/core/acpi.c diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile index 438ce27faf77..11ccc2016ab7 100644 --- a/drivers/cxl/core/Makefile +++ b/drivers/cxl/core/Makefile @@ -11,4 +11,5 @@ cxl_core-y += mbox.o cxl_core-y += pci.o cxl_core-y += hdm.o cxl_core-y += cdat.o +cxl_core-y += acpi.o cxl_core-$(CONFIG_CXL_REGION) += region.o diff --git a/drivers/cxl/core/acpi.c b/drivers/cxl/core/acpi.c new file mode 100644 index 000000000000..86dc6c9c1f24 --- /dev/null +++ b/drivers/cxl/core/acpi.c @@ -0,0 +1,99 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Copyright(c) 2022 Intel Corporation. All rights reserved. */ +#include <linux/module.h> +#include <linux/device.h> +#include <linux/kernel.h> +#include <linux/acpi.h> +#include <linux/pci.h> +#include <asm/div64.h> +#include "cxlpci.h" +#include "cxl.h" + +const guid_t acpi_cxl_qtg_id_guid = + GUID_INIT(0xF365F9A6, 0xA7DE, 0x4071, + 0xA6, 0x6A, 0xB4, 0x0C, 0x0B, 0x4F, 0x8E, 0x52); + +/** + * cxl_acpi_evaluate_qtg_dsm - Retrieve QTG ids via ACPI _DSM + * @handle: ACPI handle + * @input: bandwidth and latency data + * + * Issue QTG _DSM with accompanied bandwidth and latency data in order to get + * the QTG IDs that falls within the performance data. + */ +struct qtg_dsm_output *cxl_acpi_evaluate_qtg_dsm(acpi_handle handle, + struct qtg_dsm_input *input) +{ + struct qtg_dsm_output *output; + union acpi_object *out_obj, *out_buf, *pkg, in_buf, in_obj; + int len; + int rc; + + in_obj.type = ACPI_TYPE_PACKAGE; + in_obj.package.count = 1; + in_obj.package.elements = &in_buf; + in_buf.type = ACPI_TYPE_BUFFER; + in_buf.buffer.pointer = (u8 *)input; + in_buf.buffer.length = sizeof(u32) * 4; + + out_obj = acpi_evaluate_dsm(handle, &acpi_cxl_qtg_id_guid, 1, 1, &in_obj); + if (!out_obj) + return ERR_PTR(-ENXIO); + + if (out_obj->type != ACPI_TYPE_PACKAGE) { + rc = -ENXIO; + goto err; + } + + /* + * CXL spec v3.0 9.17.3.1 + * There should be 2 elements in the package. 1 WORD for max QTG ID supported + * by the platform, and the other a package of recommended QTGs + */ + if (out_obj->package.count != 2) { + rc = -ENXIO; + goto err; + } + + pkg = &out_obj->package.elements[1]; + if (pkg->type != ACPI_TYPE_PACKAGE) { + rc = -ENXIO; + goto err; + } + + out_buf = &pkg->package.elements[0]; + if (out_buf->type != ACPI_TYPE_BUFFER) { + rc = -ENXIO; + goto err; + } + + len = out_buf->buffer.length; + output = kmalloc(len + sizeof(*output), GFP_KERNEL); + if (!output) { + rc = -ENOMEM; + goto err; + } + + /* It's legal to have 0 QTG entries */ + if (len == 0) { + output->nr = 0; + goto out; + } + + /* Malformed package, not multiple of WORD size */ + if (len % sizeof(u16)) { + rc = -ENXIO; + goto out; + } + + output->nr = len / sizeof(u16); + memcpy(output->qtg_ids, out_buf->buffer.pointer, len); +out: + ACPI_FREE(out_obj); + return output; + +err: + ACPI_FREE(out_obj); + return ERR_PTR(rc); +} +EXPORT_SYMBOL_NS_GPL(cxl_acpi_evaluate_qtg_dsm, CXL); diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h index 849b22236f1d..e70df07f9b4b 100644 --- a/drivers/cxl/cxl.h +++ b/drivers/cxl/cxl.h @@ -719,6 +719,21 @@ int cdat_table_parse_dslbis(void *table, cdat_tbl_entry_handler handler, int cxl_dsmas_parse_entry(struct acpi_cdat_header *header, void *arg); int cxl_dslbis_parse_entry(struct acpi_cdat_header *header, void *arg); +struct qtg_dsm_input { + u32 rd_lat; + u32 wr_lat; + u32 rd_bw; + u32 wr_bw; +}; + +struct qtg_dsm_output { + int nr; + u16 qtg_ids[]; +}; + +struct qtg_dsm_output *cxl_acpi_evaluate_qtg_dsm(acpi_handle handle, + struct qtg_dsm_input *input); + /* * Unit test builds overrides this to __weak, find the 'strong' version * of these symbols in tools/testing/cxl/.