[PATCH v3 3/4] ARM: BCM: Add SMP support for Broadcom NSP

[Kapil Hali <kapilh@broadcom.com>]

Add SMP support for Broadcom's Northstar Plus SoC
cpu enable method. This changes also consolidates
iProc family's - BCM NSP and BCM Kona, platform
SMP handling in a common file.

Northstar Plus SoC is based on ARM Cortex-A9
revision r3p0 which requires configuration for ARM
Errata 764369 for SMP. This change adds the needed
configuration option.

Signed-off-by: Kapil Hali <kapilh@broadcom.com>
---
 arch/arm/mach-bcm/Kconfig                   |  2 +
 arch/arm/mach-bcm/Makefile                  |  8 ++-
 arch/arm/mach-bcm/{kona_smp.c => platsmp.c} | 82 +++++++++++++++++++++++++----
 3 files changed, 81 insertions(+), 11 deletions(-)
 rename arch/arm/mach-bcm/{kona_smp.c => platsmp.c} (75%)

diff --git a/arch/arm/mach-bcm/Kconfig b/arch/arm/mach-bcm/Kconfig
index 1679fa4..2e9dbb5 100644
--- a/arch/arm/mach-bcm/Kconfig
+++ b/arch/arm/mach-bcm/Kconfig
@@ -40,6 +40,8 @@ config ARCH_BCM_NSP
 	select ARCH_BCM_IPROC
 	select ARM_ERRATA_754322
 	select ARM_ERRATA_775420
+	select ARM_ERRATA_764369 if SMP
+	select HAVE_SMP
 	help
 	  Support for Broadcom Northstar Plus SoC.
 	  Broadcom Northstar Plus family of SoCs are used for switching control
diff --git a/arch/arm/mach-bcm/Makefile b/arch/arm/mach-bcm/Makefile
index 892261f..5193a25 100644
--- a/arch/arm/mach-bcm/Makefile
+++ b/arch/arm/mach-bcm/Makefile
@@ -14,7 +14,11 @@
 obj-$(CONFIG_ARCH_BCM_CYGNUS) +=  bcm_cygnus.o
 
 # Northstar Plus
-obj-$(CONFIG_ARCH_BCM_NSP) += bcm_nsp.o
+obj-$(CONFIG_ARCH_BCM_NSP)	+= bcm_nsp.o
+
+ifeq ($(CONFIG_ARCH_BCM_NSP),y)
+obj-$(CONFIG_SMP)		+= platsmp.o
+endif
 
 # BCM281XX
 obj-$(CONFIG_ARCH_BCM_281XX)	+= board_bcm281xx.o
@@ -23,7 +27,7 @@ obj-$(CONFIG_ARCH_BCM_281XX)	+= board_bcm281xx.o
 obj-$(CONFIG_ARCH_BCM_21664)	+= board_bcm21664.o
 
 # BCM281XX and BCM21664 SMP support
-obj-$(CONFIG_ARCH_BCM_MOBILE_SMP) += kona_smp.o
+obj-$(CONFIG_ARCH_BCM_MOBILE_SMP) += platsmp.o
 
 # BCM281XX and BCM21664 L2 cache control
 obj-$(CONFIG_ARCH_BCM_MOBILE_L2_CACHE) += kona_l2_cache.o
diff --git a/arch/arm/mach-bcm/kona_smp.c b/arch/arm/mach-bcm/platsmp.c
similarity index 75%
rename from arch/arm/mach-bcm/kona_smp.c
rename to arch/arm/mach-bcm/platsmp.c
index 66a0465..dbf14fb 100644
--- a/arch/arm/mach-bcm/kona_smp.c
+++ b/arch/arm/mach-bcm/platsmp.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014 Broadcom Corporation
+ * Copyright (C) 2014-2015 Broadcom Corporation
  * Copyright 2014 Linaro Limited
  *
  * This program is free software; you can redistribute it and/or
@@ -12,12 +12,17 @@
  * GNU General Public License for more details.
  */
 
-#include <linux/init.h>
+#include <linux/cpumask.h>
+#include <linux/delay.h>
 #include <linux/errno.h>
+#include <linux/init.h>
 #include <linux/io.h>
+#include <linux/jiffies.h>
 #include <linux/of.h>
 #include <linux/sched.h>
+#include <linux/smp.h>
 
+#include <asm/cacheflush.h>
 #include <asm/smp.h>
 #include <asm/smp_plat.h>
 #include <asm/smp_scu.h>
@@ -75,6 +80,37 @@ static int __init scu_a9_enable(void)
 	return 0;
 }
 
+static int nsp_write_lut(void)
+{
+	void __iomem *sku_rom_lut;
+	phys_addr_t secondary_startup_phy;
+
+	if (!secondary_boot) {
+		pr_warn("required secondary boot register not specified\n");
+		return -EINVAL;
+	}
+
+	sku_rom_lut = ioremap_nocache((phys_addr_t)secondary_boot,
+						sizeof(secondary_boot));
+	if (!sku_rom_lut) {
+		pr_warn("unable to ioremap SKU-ROM LUT register\n");
+		return -ENOMEM;
+	}
+
+	secondary_startup_phy = virt_to_phys(secondary_startup);
+	BUG_ON(secondary_startup_phy > (phys_addr_t)U32_MAX);
+
+	writel_relaxed(secondary_startup_phy, sku_rom_lut);
+	/*
+	 * Ensure the write is visible to the secondary core.
+	 */
+	smp_wmb();
+
+	iounmap(sku_rom_lut);
+
+	return 0;
+}
+
 static void __init bcm_smp_prepare_cpus(unsigned int max_cpus)
 {
 	static cpumask_t only_cpu_0 = { CPU_BITS_CPU0 };
@@ -95,11 +131,11 @@ static void __init bcm_smp_prepare_cpus(unsigned int max_cpus)
 	/*
 	 * Our secondary enable method requires a "secondary-boot-reg"
 	 * property to specify a register address used to request the
-	 * ROM code boot a secondary code.  If we have any trouble
+	 * ROM code boot a secondary core.  If we have any trouble
 	 * getting this we fall back to uniprocessor mode.
 	 */
 	if (of_property_read_u32(node, OF_SECONDARY_BOOT, &secondary_boot)) {
-		pr_err("%s: missing/invalid " OF_SECONDARY_BOOT " property\n",
+		pr_warn("%s: missing/invalid " OF_SECONDARY_BOOT " property\n",
 			node->name);
 		ret = -ENOENT;		/* Arrange to disable SMP */
 		goto out;
@@ -115,7 +151,6 @@ out:
 	of_node_put(node);
 	if (ret) {
 		/* Update the CPU present map to reflect uniprocessor mode */
-		BUG_ON(ret != -ENOENT);
 		pr_warn("disabling SMP\n");
 		init_cpu_present(&only_cpu_0);
 	}
@@ -139,7 +174,7 @@ out:
  * - Wait for the secondary boot register to be re-written, which
  *   indicates the secondary core has started.
  */
-static int bcm_boot_secondary(unsigned int cpu, struct task_struct *idle)
+static int kona_boot_secondary(unsigned int cpu, struct task_struct *idle)
 {
 	void __iomem *boot_reg;
 	phys_addr_t boot_func;
@@ -162,7 +197,7 @@ static int bcm_boot_secondary(unsigned int cpu, struct task_struct *idle)
 	boot_reg = ioremap_nocache((phys_addr_t)secondary_boot, sizeof(u32));
 	if (!boot_reg) {
 		pr_err("unable to map boot register for cpu %u\n", cpu_id);
-		return -ENOSYS;
+		return -ENOMEM;
 	}
 
 	/*
@@ -191,12 +226,41 @@ static int bcm_boot_secondary(unsigned int cpu, struct task_struct *idle)
 
 	pr_err("timeout waiting for cpu %u to start\n", cpu_id);
 
-	return -ENOSYS;
+	return -ENXIO;
+}
+
+static int nsp_boot_secondary(unsigned int cpu, struct task_struct *idle)
+{
+	int ret;
+
+	/*
+	 * After wake up, secondary core branches to the startup
+	 * address programmed at SKU ROM LUT location.
+	 */
+	ret = nsp_write_lut();
+	if (ret) {
+		pr_err("unable to write startup addr to SKU ROM LUT\n");
+		goto out;
+	}
+
+	/*
+	 * Send a CPU wakeup interrupt to the secondary core.
+	 */
+	arch_send_wakeup_ipi_mask(cpumask_of(cpu));
+
+out:
+	return ret;
 }
 
 static struct smp_operations bcm_smp_ops __initdata = {
 	.smp_prepare_cpus	= bcm_smp_prepare_cpus,
-	.smp_boot_secondary	= bcm_boot_secondary,
+	.smp_boot_secondary	= kona_boot_secondary,
 };
 CPU_METHOD_OF_DECLARE(bcm_smp_bcm281xx, "brcm,bcm11351-cpu-method",
 			&bcm_smp_ops);
+
+struct smp_operations nsp_smp_ops __initdata = {
+	.smp_prepare_cpus	= bcm_smp_prepare_cpus,
+	.smp_boot_secondary	= nsp_boot_secondary,
+};
+CPU_METHOD_OF_DECLARE(bcm_smp_nsp, "brcm,bcm-nsp-smp", &nsp_smp_ops);
-- 
2.1.0