arm: npcm: add basic support for Nuvoton BMCs

Adds basic support for the Nuvoton NPCM750 BMC.

Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
Reviewed-by: Tomer Maimon <tmaimon77@gmail.com>
Reviewed-by: Avi Fishman <avifishman70@gmail.com>
Tested-by: Tomer Maimon <tmaimon77@gmail.com>
Tested-by: Avi Fishman <avifishman70@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/Kconfig

@@ -779,6 +779,8 @@ source "arch/arm/mach-netx/Kconfig"
 
 source "arch/arm/mach-nomadik/Kconfig"
 
+source "arch/arm/mach-npcm/Kconfig"
+
 source "arch/arm/mach-nspire/Kconfig"
 
 source "arch/arm/plat-omap/Kconfig"

arch/arm/Makefile

@@ -196,6 +196,7 @@ machine-$(CONFIG_ARCH_MEDIATEK)		+= mediatek
 machine-$(CONFIG_ARCH_MXS)		+= mxs
 machine-$(CONFIG_ARCH_NETX)		+= netx
 machine-$(CONFIG_ARCH_NOMADIK)		+= nomadik
+machine-$(CONFIG_ARCH_NPCM)		+= npcm
 machine-$(CONFIG_ARCH_NSPIRE)		+= nspire
 machine-$(CONFIG_ARCH_OXNAS)		+= oxnas
 machine-$(CONFIG_ARCH_OMAP1)		+= omap1

arch/arm/mach-npcm/Kconfig

+menuconfig ARCH_NPCM
+	bool "Nuvoton NPCM Architecture"
+	select ARCH_REQUIRE_GPIOLIB
+	select USE_OF
+	select PINCTRL
+	select PINCTRL_NPCM7XX
+
+if ARCH_NPCM
+
+comment "NPCM7XX CPU type"
+
+config ARCH_NPCM750
+	depends on ARCH_NPCM && ARCH_MULTI_V7
+	bool "Support for NPCM750 BMC CPU (Poleg)"
+	select CACHE_L2X0
+	select CPU_V7
+	select ARM_GIC
+	select HAVE_SMP
+	select SMP
+	select SMP_ON_UP
+	select HAVE_ARM_SCU
+	select HAVE_ARM_TWD if SMP
+	select ARM_ERRATA_720789
+	select ARM_ERRATA_754322
+	select ARM_ERRATA_764369
+	select ARM_ERRATA_794072
+	select PL310_ERRATA_588369
+	select PL310_ERRATA_727915
+	select USB_EHCI_ROOT_HUB_TT
+	select USB_ARCH_HAS_HCD
+	select USB_ARCH_HAS_EHCI
+	select USB_EHCI_HCD
+	select USB_ARCH_HAS_OHCI
+	select USB_OHCI_HCD
+	select USB
+	select FIQ
+	select CPU_USE_DOMAINS
+	select GENERIC_CLOCKEVENTS
+	select CLKDEV_LOOKUP
+	select COMMON_CLK if OF
+	select NPCM750_TIMER
+	select MFD_SYSCON
+	help
+	  Support for NPCM750 BMC CPU (Poleg).
+
+	  Nuvoton NPCM750 BMC based on the Cortex A9.
+
+endif

arch/arm/mach-npcm/Makefile

+AFLAGS_headsmp.o		+= -march=armv7-a
+
+obj-$(CONFIG_ARCH_NPCM750)	+= npcm7xx.o platsmp.o headsmp.o

arch/arm/mach-npcm/headsmp.S

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018 Nuvoton Technology corporation.
+// Copyright 2018 Google, Inc.
+
+#include <linux/linkage.h>
+#include <linux/init.h>
+#include <asm/assembler.h>
+
+/*
+ * The boot ROM does not start secondary CPUs in SVC mode, so we need to do that
+ * here.
+ */
+ENTRY(npcm7xx_secondary_startup)
+	safe_svcmode_maskall r0
+
+	b	secondary_startup
+ENDPROC(npcm7xx_secondary_startup)

arch/arm/mach-npcm/npcm7xx.c

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018 Nuvoton Technology corporation.
+// Copyright 2018 Google, Inc.
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <asm/mach/arch.h>
+#include <asm/mach-types.h>
+#include <asm/mach/map.h>
+#include <asm/hardware/cache-l2x0.h>
+
+static const char *const npcm7xx_dt_match[] = {
+	"nuvoton,npcm750",
+	NULL
+};
+
+DT_MACHINE_START(NPCM7XX_DT, "NPCM7XX Chip family")
+	.atag_offset	= 0x100,
+	.dt_compat	= npcm7xx_dt_match,
+MACHINE_END

arch/arm/mach-npcm/platsmp.c

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018 Nuvoton Technology corporation.
+// Copyright 2018 Google, Inc.
+
+#define pr_fmt(fmt) "nuvoton,npcm7xx-smp: " fmt
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/smp.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_platform.h>
+#include <linux/of_address.h>
+#include <asm/cacheflush.h>
+#include <asm/smp.h>
+#include <asm/smp_plat.h>
+#include <asm/smp_scu.h>
+
+#define NPCM7XX_SCRPAD_REG 0x13c
+
+extern void npcm7xx_secondary_startup(void);
+
+static int npcm7xx_smp_boot_secondary(unsigned int cpu,
+				      struct task_struct *idle)
+{
+	struct device_node *gcr_np;
+	void __iomem *gcr_base;
+	int ret = 0;
+
+	gcr_np = of_find_compatible_node(NULL, NULL, "nuvoton,npcm750-gcr");
+	if (!gcr_np) {
+		pr_err("no gcr device node\n");
+		ret = -ENODEV;
+		goto out;
+	}
+	gcr_base = of_iomap(gcr_np, 0);
+	if (!gcr_base) {
+		pr_err("could not iomap gcr");
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	/* give boot ROM kernel start address. */
+	iowrite32(__pa_symbol(npcm7xx_secondary_startup), gcr_base +
+		  NPCM7XX_SCRPAD_REG);
+	/* make sure the previous write is seen by all observers. */
+	dsb_sev();
+
+	iounmap(gcr_base);
+out:
+	return ret;
+}
+
+static void __init npcm7xx_smp_prepare_cpus(unsigned int max_cpus)
+{
+	struct device_node *scu_np;
+	void __iomem *scu_base;
+
+	scu_np = of_find_compatible_node(NULL, NULL, "arm,cortex-a9-scu");
+	if (!scu_np) {
+		pr_err("no scu device node\n");
+		return;
+	}
+	scu_base = of_iomap(scu_np, 0);
+	if (!scu_base) {
+		pr_err("could not iomap scu");
+		return;
+	}
+
+	scu_enable(scu_base);
+
+	iounmap(scu_base);
+}
+
+static struct smp_operations npcm7xx_smp_ops __initdata = {
+	.smp_prepare_cpus = npcm7xx_smp_prepare_cpus,
+	.smp_boot_secondary = npcm7xx_smp_boot_secondary,
+};
+
+CPU_METHOD_OF_DECLARE(npcm7xx_smp, "nuvoton,npcm750-smp", &npcm7xx_smp_ops);