forked from Minki/linux
7673f5b14f
All low-level PM/SMP code using virt_to_phys() should actually use
__pa_symbol() against kernel symbols. Update the documentation to move
away from virt_to_phys().
Cfr. commit 6996cbb237 ("ARM: 8641/1: treewide: Replace uses of
virt_to_phys with __pa_symbol")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
71 lines
2.2 KiB
Plaintext
71 lines
2.2 KiB
Plaintext
Interface for registering and calling firmware-specific operations for ARM.
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----
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Written by Tomasz Figa <t.figa@samsung.com>
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Some boards are running with secure firmware running in TrustZone secure
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world, which changes the way some things have to be initialized. This makes
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a need to provide an interface for such platforms to specify available firmware
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operations and call them when needed.
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Firmware operations can be specified by filling in a struct firmware_ops
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with appropriate callbacks and then registering it with register_firmware_ops()
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function.
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void register_firmware_ops(const struct firmware_ops *ops)
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The ops pointer must be non-NULL. More information about struct firmware_ops
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and its members can be found in arch/arm/include/asm/firmware.h header.
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There is a default, empty set of operations provided, so there is no need to
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set anything if platform does not require firmware operations.
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To call a firmware operation, a helper macro is provided
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#define call_firmware_op(op, ...) \
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((firmware_ops->op) ? firmware_ops->op(__VA_ARGS__) : (-ENOSYS))
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the macro checks if the operation is provided and calls it or otherwise returns
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-ENOSYS to signal that given operation is not available (for example, to allow
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fallback to legacy operation).
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Example of registering firmware operations:
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/* board file */
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static int platformX_do_idle(void)
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{
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/* tell platformX firmware to enter idle */
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return 0;
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}
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static int platformX_cpu_boot(int i)
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{
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/* tell platformX firmware to boot CPU i */
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return 0;
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}
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static const struct firmware_ops platformX_firmware_ops = {
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.do_idle = exynos_do_idle,
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.cpu_boot = exynos_cpu_boot,
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/* other operations not available on platformX */
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};
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/* init_early callback of machine descriptor */
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static void __init board_init_early(void)
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{
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register_firmware_ops(&platformX_firmware_ops);
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}
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Example of using a firmware operation:
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/* some platform code, e.g. SMP initialization */
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__raw_writel(__pa_symbol(exynos4_secondary_startup),
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CPU1_BOOT_REG);
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/* Call Exynos specific smc call */
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if (call_firmware_op(cpu_boot, cpu) == -ENOSYS)
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cpu_boot_legacy(...); /* Try legacy way */
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gic_raise_softirq(cpumask_of(cpu), 1);
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