arm: vexpress: Remove obsolete RTSM DCSCB support

The Arm Versatile DCSCB support is unused as the compatible
"arm,rtsm,dcscb" is unused in any .dts file. It was only ever
implemented on a s/w model (RTSM).
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20240510123238.3904779-1-robh@kernel.orgSigned-off-by: Sudeep Holla <sudeep.holla@arm.com>

arch/arm/configs/vexpress_defconfig

@@ -14,7 +14,6 @@ CONFIG_CPUSETS=y
 CONFIG_BLK_DEV_INITRD=y
 CONFIG_PROFILING=y
 CONFIG_ARCH_VEXPRESS=y
-CONFIG_ARCH_VEXPRESS_DCSCB=y
 CONFIG_ARCH_VEXPRESS_TC2_PM=y
 CONFIG_SMP=y
 CONFIG_HAVE_ARM_ARCH_TIMER=y

arch/arm/mach-versatile/Kconfig

@@ -278,15 +278,6 @@ config ARCH_VEXPRESS_CORTEX_A5_A9_ERRATA
 	  build a working kernel, you must also enable relevant core
 	  tile support or Flattened Device Tree based support options.
 
-config ARCH_VEXPRESS_DCSCB
-	bool "Dual Cluster System Control Block (DCSCB) support"
-	depends on MCPM
-	select ARM_CCI400_PORT_CTRL
-	help
-	  Support for the Dual Cluster System Configuration Block (DCSCB).
-	  This is needed to provide CPU and cluster power management
-	  on RTSM implementing big.LITTLE.
-
 config ARCH_VEXPRESS_SPC
 	bool "Versatile Express Serial Power Controller (SPC)"
 	select PM_OPP

arch/arm/mach-versatile/Makefile

@@ -16,9 +16,6 @@ obj-$(CONFIG_ARCH_REALVIEW)		+= realview.o
 
 # vexpress
 obj-$(CONFIG_ARCH_VEXPRESS)		:= v2m.o
-obj-$(CONFIG_ARCH_VEXPRESS_DCSCB)	+= dcscb.o	dcscb_setup.o
-CFLAGS_dcscb.o				+= -march=armv7-a
-CFLAGS_REMOVE_dcscb.o			= -pg
 obj-$(CONFIG_ARCH_VEXPRESS_SPC)		+= spc.o
 CFLAGS_REMOVE_spc.o			= -pg
 obj-$(CONFIG_ARCH_VEXPRESS_TC2_PM)	+= tc2_pm.o

arch/arm/mach-versatile/dcscb.c

-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * dcscb.c - Dual Cluster System Configuration Block
- *
- * Created by:	Nicolas Pitre, May 2012
- * Copyright:	(C) 2012-2013  Linaro Limited
- */
-
-#include <linux/init.h>
-#include <linux/kernel.h>
-#include <linux/io.h>
-#include <linux/errno.h>
-#include <linux/of_address.h>
-#include <linux/vexpress.h>
-#include <linux/arm-cci.h>
-
-#include <asm/mcpm.h>
-#include <asm/proc-fns.h>
-#include <asm/cacheflush.h>
-#include <asm/cputype.h>
-#include <asm/cp15.h>
-
-#include "vexpress.h"
-
-#define RST_HOLD0	0x0
-#define RST_HOLD1	0x4
-#define SYS_SWRESET	0x8
-#define RST_STAT0	0xc
-#define RST_STAT1	0x10
-#define EAG_CFG_R	0x20
-#define EAG_CFG_W	0x24
-#define KFC_CFG_R	0x28
-#define KFC_CFG_W	0x2c
-#define DCS_CFG_R	0x30
-
-static void __iomem *dcscb_base;
-static int dcscb_allcpus_mask[2];
-
-static int dcscb_cpu_powerup(unsigned int cpu, unsigned int cluster)
-{
-	unsigned int rst_hold, cpumask = (1 << cpu);
-
-	pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
-	if (cluster >= 2 || !(cpumask & dcscb_allcpus_mask[cluster]))
-		return -EINVAL;
-
-	rst_hold = readl_relaxed(dcscb_base + RST_HOLD0 + cluster * 4);
-	rst_hold &= ~(cpumask | (cpumask << 4));
-	writel_relaxed(rst_hold, dcscb_base + RST_HOLD0 + cluster * 4);
-	return 0;
-}
-
-static int dcscb_cluster_powerup(unsigned int cluster)
-{
-	unsigned int rst_hold;
-
-	pr_debug("%s: cluster %u\n", __func__, cluster);
-	if (cluster >= 2)
-		return -EINVAL;
-
-	/* remove cluster reset and add individual CPU's reset */
-	rst_hold = readl_relaxed(dcscb_base + RST_HOLD0 + cluster * 4);
-	rst_hold &= ~(1 << 8);
-	rst_hold |= dcscb_allcpus_mask[cluster];
-	writel_relaxed(rst_hold, dcscb_base + RST_HOLD0 + cluster * 4);
-	return 0;
-}
-
-static void dcscb_cpu_powerdown_prepare(unsigned int cpu, unsigned int cluster)
-{
-	unsigned int rst_hold;
-
-	pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
-	BUG_ON(cluster >= 2 || !((1 << cpu) & dcscb_allcpus_mask[cluster]));
-
-	rst_hold = readl_relaxed(dcscb_base + RST_HOLD0 + cluster * 4);
-	rst_hold |= (1 << cpu);
-	writel_relaxed(rst_hold, dcscb_base + RST_HOLD0 + cluster * 4);
-}
-
-static void dcscb_cluster_powerdown_prepare(unsigned int cluster)
-{
-	unsigned int rst_hold;
-
-	pr_debug("%s: cluster %u\n", __func__, cluster);
-	BUG_ON(cluster >= 2);
-
-	rst_hold = readl_relaxed(dcscb_base + RST_HOLD0 + cluster * 4);
-	rst_hold |= (1 << 8);
-	writel_relaxed(rst_hold, dcscb_base + RST_HOLD0 + cluster * 4);
-}
-
-static void dcscb_cpu_cache_disable(void)
-{
-	/* Disable and flush the local CPU cache. */
-	v7_exit_coherency_flush(louis);
-}
-
-static void dcscb_cluster_cache_disable(void)
-{
-	/* Flush all cache levels for this cluster. */
-	v7_exit_coherency_flush(all);
-
-	/*
-	 * A full outer cache flush could be needed at this point
-	 * on platforms with such a cache, depending on where the
-	 * outer cache sits. In some cases the notion of a "last
-	 * cluster standing" would need to be implemented if the
-	 * outer cache is shared across clusters. In any case, when
-	 * the outer cache needs flushing, there is no concurrent
-	 * access to the cache controller to worry about and no
-	 * special locking besides what is already provided by the
-	 * MCPM state machinery is needed.
-	 */
-
-	/*
-	 * Disable cluster-level coherency by masking
-	 * incoming snoops and DVM messages:
-	 */
-	cci_disable_port_by_cpu(read_cpuid_mpidr());
-}
-
-static const struct mcpm_platform_ops dcscb_power_ops = {
-	.cpu_powerup		= dcscb_cpu_powerup,
-	.cluster_powerup	= dcscb_cluster_powerup,
-	.cpu_powerdown_prepare	= dcscb_cpu_powerdown_prepare,
-	.cluster_powerdown_prepare = dcscb_cluster_powerdown_prepare,
-	.cpu_cache_disable	= dcscb_cpu_cache_disable,
-	.cluster_cache_disable	= dcscb_cluster_cache_disable,
-};
-
-extern void dcscb_power_up_setup(unsigned int affinity_level);
-
-static int __init dcscb_init(void)
-{
-	struct device_node *node;
-	unsigned int cfg;
-	int ret;
-
-	if (!cci_probed())
-		return -ENODEV;
-
-	node = of_find_compatible_node(NULL, NULL, "arm,rtsm,dcscb");
-	if (!node)
-		return -ENODEV;
-	dcscb_base = of_iomap(node, 0);
-	of_node_put(node);
-	if (!dcscb_base)
-		return -EADDRNOTAVAIL;
-	cfg = readl_relaxed(dcscb_base + DCS_CFG_R);
-	dcscb_allcpus_mask[0] = (1 << (((cfg >> 16) >> (0 << 2)) & 0xf)) - 1;
-	dcscb_allcpus_mask[1] = (1 << (((cfg >> 16) >> (1 << 2)) & 0xf)) - 1;
-
-	ret = mcpm_platform_register(&dcscb_power_ops);
-	if (!ret)
-		ret = mcpm_sync_init(dcscb_power_up_setup);
-	if (ret) {
-		iounmap(dcscb_base);
-		return ret;
-	}
-
-	pr_info("VExpress DCSCB support installed\n");
-
-	/*
-	 * Future entries into the kernel can now go
-	 * through the cluster entry vectors.
-	 */
-	vexpress_flags_set(__pa_symbol(mcpm_entry_point));
-
-	return 0;
-}
-
-early_initcall(dcscb_init);

arch/arm/mach-versatile/dcscb_setup.S

-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * Created by:  Dave Martin, 2012-06-22
- * Copyright:   (C) 2012-2013  Linaro Limited
- */
-
-#include <linux/linkage.h>
-
-
-ENTRY(dcscb_power_up_setup)
-
-	cmp	r0, #0			@ check affinity level
-	beq	2f
-
-/*
- * Enable cluster-level coherency, in preparation for turning on the MMU.
- * The ACTLR SMP bit does not need to be set here, because cpu_resume()
- * already restores that.
- *
- * A15/A7 may not require explicit L2 invalidation on reset, dependent
- * on hardware integration decisions.
- * For now, this code assumes that L2 is either already invalidated,
- * or invalidation is not required.
- */
-
-	b	cci_enable_port_for_self
-
-2:	@ Implementation-specific local CPU setup operations should go here,
-	@ if any.  In this case, there is nothing to do.
-
-	bx	lr
-
-ENDPROC(dcscb_power_up_setup)