Interface for registering and calling firmware-specific operations for ARM¶
Written by Tomasz Figa <t.figa@samsung.com>
Some boards are running with secure firmware running in TrustZone secureworld, which changes the way some things have to be initialized. This makesa need to provide an interface for such platforms to specify available firmwareoperations and call them when needed.
Firmware operations can be specified by filling in astructfirmware_opswith appropriate callbacks and then registering it withregister_firmware_ops()function:
void register_firmware_ops(const struct firmware_ops *ops)
The ops pointer must be non-NULL. More information aboutstructfirmware_opsand its members can be found in arch/arm/include/asm/firmware.h header.
There is a default, empty set of operations provided, so there is no need toset anything if platform does not require firmware operations.
To call a firmware operation, a helper macro is provided:
#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 allowfallback to legacy operation).
Example of registering firmware operations:
/* board file */static int platformX_do_idle(void){ /* tell platformX firmware to enter idle */ return 0;}static int platformX_cpu_boot(int i){ /* tell platformX firmware to boot 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 */};/* init_early callback of machine descriptor */static void __init board_init_early(void){ register_firmware_ops(&platformX_firmware_ops);}Example of using a firmware operation:
/* some platform code, e.g. SMP initialization */__raw_writel(__pa_symbol(exynos4_secondary_startup), CPU1_BOOT_REG);/* Call Exynos specific smc call */if (call_firmware_op(cpu_boot, cpu) == -ENOSYS) cpu_boot_legacy(...); /* Try legacy way */gic_raise_softirq(cpumask_of(cpu), 1);