From 3f20fb1153b374737acd40d42cb3cab2ae5dae35 Mon Sep 17 00:00:00 2001 From: Thomas Petazzoni Date: Mon, 14 Apr 2014 15:50:28 +0200 Subject: [PATCH] ARM: mvebu: introduce CPU reset code The Armada 370 and Armada XP have registers that allow to reset the CPUs, which is particularly useful to take the secondary CPUs out of reset in the context of the SMP support. Unfortunately, an implementation mistake was originally made and the support for these registers was integrated into the PMSU driver, which is in fact completely unrelated. And it turns out that the Armada 375 has the same CPU reset registers, but does not have the PMSU registers. Therefore, this commit creates a small CPU reset driver. All it does is provide a simple mvebu_cpu_reset_deassert() function that the SMP support code can call to take secondary CPUs out of reset. As of this commit, the driver isn't being used, it will be used through changes in the following commits. Note that we initially planned to use the 'reset controller' framework, but it requires the addition of "resets" properties in the Device Tree, which are causing too many problems if we want to keep the Device Tree backward compatibility. Moreover, the 'reset controller' framework is mainly useful when a device driver needs to request a reset of its device from a separate reset controller. In our case, the CPU reset handling and the SMP core code are both located in arch/arm/mach-mvebu/ and are tightly linked together, so there's no real benefit in going through a separate framework. Signed-off-by: Thomas Petazzoni Link: https://lkml.kernel.org/r/1397483433-25836-2-git-send-email-thomas.petazzoni@free-electrons.com Signed-off-by: Jason Cooper --- .../bindings/arm/armada-cpu-reset.txt | 14 ++++ arch/arm/mach-mvebu/Makefile | 2 +- arch/arm/mach-mvebu/common.h | 1 + arch/arm/mach-mvebu/cpu-reset.c | 82 +++++++++++++++++++ 4 files changed, 98 insertions(+), 1 deletion(-) create mode 100644 Documentation/devicetree/bindings/arm/armada-cpu-reset.txt create mode 100644 arch/arm/mach-mvebu/cpu-reset.c diff --git a/Documentation/devicetree/bindings/arm/armada-cpu-reset.txt b/Documentation/devicetree/bindings/arm/armada-cpu-reset.txt new file mode 100644 index 00000000000..b63a7b6ab99 --- /dev/null +++ b/Documentation/devicetree/bindings/arm/armada-cpu-reset.txt @@ -0,0 +1,14 @@ +Marvell Armada CPU reset controller +=================================== + +Required properties: + +- compatible: Should be "marvell,armada-370-cpu-reset". + +- reg: should be register base and length as documented in the + datasheet for the CPU reset registers + +cpurst: cpurst@20800 { + compatible = "marvell,armada-370-cpu-reset"; + reg = <0x20800 0x20>; +}; diff --git a/arch/arm/mach-mvebu/Makefile b/arch/arm/mach-mvebu/Makefile index a63e43b6b45..f9cfab05c5f 100644 --- a/arch/arm/mach-mvebu/Makefile +++ b/arch/arm/mach-mvebu/Makefile @@ -3,7 +3,7 @@ ccflags-$(CONFIG_ARCH_MULTIPLATFORM) := -I$(srctree)/$(src)/include \ AFLAGS_coherency_ll.o := -Wa,-march=armv7-a -obj-y += system-controller.o mvebu-soc-id.o +obj-y += system-controller.o mvebu-soc-id.o cpu-reset.o obj-$(CONFIG_MACH_MVEBU_V7) += board-v7.o obj-$(CONFIG_MACH_DOVE) += dove.o obj-$(CONFIG_ARCH_MVEBU) += coherency.o coherency_ll.o pmsu.o diff --git a/arch/arm/mach-mvebu/common.h b/arch/arm/mach-mvebu/common.h index 55449c487c9..cfb129b144c 100644 --- a/arch/arm/mach-mvebu/common.h +++ b/arch/arm/mach-mvebu/common.h @@ -18,6 +18,7 @@ #include void mvebu_restart(enum reboot_mode mode, const char *cmd); +int mvebu_cpu_reset_deassert(int cpu); void armada_xp_cpu_die(unsigned int cpu); diff --git a/arch/arm/mach-mvebu/cpu-reset.c b/arch/arm/mach-mvebu/cpu-reset.c new file mode 100644 index 00000000000..4ff4ce77f8b --- /dev/null +++ b/arch/arm/mach-mvebu/cpu-reset.c @@ -0,0 +1,82 @@ +/* + * Copyright (C) 2014 Marvell + * + * Thomas Petazzoni + * + * This file is licensed under the terms of the GNU General Public + * License version 2. This program is licensed "as is" without any + * warranty of any kind, whether express or implied. + */ + +#define pr_fmt(fmt) "mvebu-cpureset: " fmt + +#include +#include +#include +#include +#include +#include "armada-370-xp.h" + +static void __iomem *cpu_reset_base; +static size_t cpu_reset_size; + +#define CPU_RESET_OFFSET(cpu) (cpu * 0x8) +#define CPU_RESET_ASSERT BIT(0) + +int mvebu_cpu_reset_deassert(int cpu) +{ + u32 reg; + + if (!cpu_reset_base) + return -ENODEV; + + if (CPU_RESET_OFFSET(cpu) >= cpu_reset_size) + return -EINVAL; + + reg = readl(cpu_reset_base + CPU_RESET_OFFSET(cpu)); + reg &= ~CPU_RESET_ASSERT; + writel(reg, cpu_reset_base + CPU_RESET_OFFSET(cpu)); + + return 0; +} + +static int __init mvebu_cpu_reset_init(void) +{ + struct device_node *np; + struct resource res; + int ret = 0; + + np = of_find_compatible_node(NULL, NULL, + "marvell,armada-370-cpu-reset"); + if (!np) + return 0; + + if (of_address_to_resource(np, 0, &res)) { + pr_err("unable to get resource\n"); + ret = -ENOENT; + goto out; + } + + if (!request_mem_region(res.start, resource_size(&res), + np->full_name)) { + pr_err("unable to request region\n"); + ret = -EBUSY; + goto out; + } + + cpu_reset_base = ioremap(res.start, resource_size(&res)); + if (!cpu_reset_base) { + pr_err("unable to map registers\n"); + release_mem_region(res.start, resource_size(&res)); + ret = -ENOMEM; + goto out; + } + + cpu_reset_size = resource_size(&res); + +out: + of_node_put(np); + return ret; +} + +early_initcall(mvebu_cpu_reset_init); -- 2.46.0