Probing MPAM is convoluted. MSCs that are integrated with a CPU may
only be accessible from those CPUs, and they may not be online.
Touching the hardware early is pointless as MPAM can't be used until
the system-wide common values for num_partid and num_pmg have been
discovered.

Start with driver probe/remove and mapping the MSC.

CC: Carl Worth <redacted>
Tested-by: Fenghua Yu <fenghuay@nvidia.com>
Signed-off-by: James Morse <james.morse@arm.com>
---
Changes since v2:
 * Comment in Kconfig about why EXPERT.
 * Dropped duplicate depends.
 * Fixed duplicate return statement.
 * Restructured driver probe to have a do_ function to allow breaks to be
   return instead...
 * Removed resctrl.h include, added spinlock.h
 * Removed stray DT function prototype
 * Removed stray PCC variables in struct mpam_msc.
 * Used ccflags not cflags for debug define.
 * Moved srcu header include to internal.h
 * Moved mpam_msc_destroy() into this patch.

Changes since v1:
 * Avoid selecting driver on other architectrues.
 * Removed PCC support stub.
 * Use for_each_available_child_of_node_scoped() and of_property_read_reg()
 * Clarified a comment.
 * Stopped using mpam_num_msc as an id,a and made it atomic.
 * Size of -1 returned from cache_of_calculate_id()
 * Renamed some struct members.
 * Made a bunch of pr_err() dev_err_ocne().
 * Used more cleanup magic.
 * Inlined a print message.
 * Fixed error propagation from mpam_dt_parse_resources().
 * Moved cache accessibility checks earlier.
 * Change cleanup macro to use IS_ERR_OR_NULL().

Changes since RFC:
 * Check for status=broken DT devices.
 * Moved all the files around.
 * Made Kconfig symbols depend on EXPERT
---
 arch/arm64/Kconfig              |   1 +
 drivers/Kconfig                 |   2 +
 drivers/Makefile                |   1 +
 drivers/acpi/arm64/mpam.c       |   7 ++
 drivers/resctrl/Kconfig         |  13 +++
 drivers/resctrl/Makefile        |   4 +
 drivers/resctrl/mpam_devices.c  | 190 ++++++++++++++++++++++++++++++++
 drivers/resctrl/mpam_internal.h |  52 +++++++++
 include/linux/acpi.h            |   2 +-
 9 files changed, 271 insertions(+), 1 deletion(-)
 create mode 100644 drivers/resctrl/Kconfig
 create mode 100644 drivers/resctrl/Makefile
 create mode 100644 drivers/resctrl/mpam_devices.c
 create mode 100644 drivers/resctrl/mpam_internal.h

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index c5e66d5d72cd..004d58cfbff8 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig

@@ -2025,6 +2025,7 @@ config ARM64_TLB_RANGE
 
 config ARM64_MPAM
 	bool "Enable support for MPAM"
+	select ARM64_MPAM_DRIVER if EXPERT	# does nothing yet
 	select ACPI_MPAM if ACPI
 	help
 	  Memory System Resource Partitioning and Monitoring (MPAM) is an

diff --git a/drivers/Kconfig b/drivers/Kconfig
index 4915a63866b0..3054b50a2f4c 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig

@@ -251,4 +251,6 @@ source "drivers/hte/Kconfig"
 
 source "drivers/cdx/Kconfig"
 
+source "drivers/resctrl/Kconfig"
+
 endmenu

diff --git a/drivers/Makefile b/drivers/Makefile
index 8e1ffa4358d5..20eb17596b89 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile

@@ -194,6 +194,7 @@ obj-$(CONFIG_HTE)		+= hte/
 obj-$(CONFIG_DRM_ACCEL)		+= accel/
 obj-$(CONFIG_CDX_BUS)		+= cdx/
 obj-$(CONFIG_DPLL)		+= dpll/
+obj-y				+= resctrl/
 
 obj-$(CONFIG_DIBS)		+= dibs/
 obj-$(CONFIG_S390)		+= s390/

diff --git a/drivers/acpi/arm64/mpam.c b/drivers/acpi/arm64/mpam.c
index 59712397025d..51c6f5fd4a5e 100644
--- a/drivers/acpi/arm64/mpam.c
+++ b/drivers/acpi/arm64/mpam.c

@@ -337,6 +337,13 @@ static int __init acpi_mpam_parse(void)
 	return 0;
 }
 
+/**
+ * acpi_mpam_count_msc() - Count the number of MSC described by firmware.
+ *
+ * Returns the number of of MSC, or zero for an error.
+ *
+ * This can be called before or in parallel with acpi_mpam_parse().
+ */

diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 9d66421f68ff..70f075b397ce 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h

@@ -231,7 +231,7 @@ static inline struct acpi_table_header *acpi_get_table_ret(char *signature, u32
 		return ERR_PTR(-ENOENT);
 	return table;
 }
-DEFINE_FREE(acpi_table, struct acpi_table_header *, if (!IS_ERR(_T)) acpi_put_table(_T))
+DEFINE_FREE(acpi_table, struct acpi_table_header *, if (!IS_ERR_OR_NULL(_T)) acpi_put_table(_T))