Documentation\arm\firmware-优快云博客

本文详细介绍了ARM平台下固件特定操作的注册和调用接口，包括CPU空闲模式进入、物理CPU启动地址设置、CPU启动、L2缓存初始化等操作。通过struct firmware_ops结构体定义操作，使用register_firmware_ops函数注册接口，以及call_firmware_op宏调用操作。示例代码展示了如何在主板文件中注册和使用这些操作。

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Interface for registering and calling firmware-specific operations for ARM.
ARM的接口注册和固件特定操作的调用

----
Written by Tomasz Figa <t.figa@samsung.com>

作者：Tomasz Figa <t.figa@samsung.com>

Some boards are running with secure firmware running in TrustZone secure world, which changes the way some things have to be initialized.
一些主板要在安全固件上运行，而安全固件运行在TrustZone安全环境中——TrustZone安全环境可以改变一些事物初始化的方式。

This makes a need to provide an interface for such platforms to specify available firmware operations and call them when needed.
这使得需要这样的平台提供了一个接口指定可用的固件操作，并在需要时调用它们。

Firmware operations can be specified using struct firmware_ops：
利用struct firmware_ops可以指定固件操作：

struct firmware_ops {
  /*
  * Enters CPU idle mode
                  CPU进入空闲状态
  */
  int (*do_idle)(void);
  /*
  * Sets boot address of specified physical CPU
                  设置指定的物理CPU的启动地址
  */
  int (*set_cpu_boot_addr)(int cpu, unsigned long boot_addr);
  /*
  * Boots specified physical CPU
                  启动指定的物理CPU
  */
  int (*cpu_boot)(int cpu);
  /*
  * Initializes L2 cache
                  初始化L2缓存
  */
  int (*l2x0_init)(void);
};

and then registered with register_firmware_ops function void register_firmware_ops(const struct firmware_ops *ops) the ops pointer must be non-NULL.
然后注册register_firmware_ops函数：void register_firmware_ops(const struct firmware_ops *ops) ops指针必须非空。

There is a default, empty set of operations provided, so there is no need to set anything if platform does not require firmware operations.
register_firmware_ops函数包含了一个默认的空的集合，所以如果这个平台不要求固件操作，则就没有必要设置什么了。

To call a firmware operation, a helper macro is provided：
为了调用固件操作，需要包含一个宏定义：

#define call_firmware_op(op, ...)
((firmware_ops->op) ? firmware_ops->op(__VA_ARGS__) : (-ENOSYS))

the macro checks if the operation is provided and calls it or otherwise returns -ENOSYS to signal that given operation is not available (for example, to allow fallback to legacy operation).
若包含宏并调用它，则可进行宏检验或者返回-ENOSYS信号以表明该操作不可行（例如：允许返回legacy操作）。

Example of registering firmware operations:

/* board file */
   主板文件

static int platformX_do_idle(void) {
                               /* tell platformX firmware to enter idle */
                    告诉platformX固件进入空闲状态

                                  return 0; }

static int platformX_cpu_boot(int i) {
                              /* tell platformX firmware to boot CPU i */
                                告诉platformX固件去启动CPU i

return 0; }

static const struct firmware_ops platformX_firmware_ops = {
.do_idle = exynos_do_idle, .cpu_boot = exynos_cpu_boot；

                            /* other operations not available on platformX */ };
                               其他操作在platformX上不可行

                            /* init_early callback of machine descriptor */
                               init_early的回调机理描述

static void __init board_init_early(void) {
register_firmware_ops(&platformX_firmware_ops); }

Example of using a firmware operation:
利用固件操作的例子：

/* some platform code, e.g. SMP initialization */
一些平台的代码，例如SMP初始化

__raw_writel(virt_to_phys(exynos4_secondary_startup),CPU1_BOOT_REG);

/* Call Exynos specific smc call */
调用Exynos specific smc call

if (call_firmware_op(cpu_boot, cpu) == -ENOSYS)

cpu_boot_legacy(...);

/* Try legacy way */
尝试legacy方式

gic_raise_softirq(cpumask_of(cpu), 1);