Merge tag 'docs/v5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media

Pull rst conversion of docs from Mauro Carvalho Chehab:
 "As agreed with Jon, I'm sending this big series directly to you, c/c
  him, as this series required a special care, in order to avoid
  conflicts with other trees"

* tag 'docs/v5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (77 commits)
  docs: kbuild: fix build with pdf and fix some minor issues
  docs: block: fix pdf output
  docs: arm: fix a breakage with pdf output
  docs: don't use nested tables
  docs: gpio: add sysfs interface to the admin-guide
  docs: locking: add it to the main index
  docs: add some directories to the main documentation index
  docs: add SPDX tags to new index files
  docs: add a memory-devices subdir to driver-api
  docs: phy: place documentation under driver-api
  docs: serial: move it to the driver-api
  docs: driver-api: add remaining converted dirs to it
  docs: driver-api: add xilinx driver API documentation
  docs: driver-api: add a series of orphaned documents
  docs: admin-guide: add a series of orphaned documents
  docs: cgroup-v1: add it to the admin-guide book
  docs: aoe: add it to the driver-api book
  docs: add some documentation dirs to the driver-api book
  docs: driver-model: move it to the driver-api book
  docs: lp855x-driver.rst: add it to the driver-api book
  ...

1 files changed, 72 insertions, 0 deletions

diff --git a/Documentation/arm/firmware.rst b/Documentation/arm/firmware.rst
new file mode 100644
index 000000000000..efd844baec1d
--- /dev/null
+++ b/Documentation/arm/firmware.rst
@@ -0,0 +1,72 @@
+==========================================================================
+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 secure
+world, which changes the way some things have to be initialized. This makes
+a need to provide an interface for such platforms to specify available firmware
+operations and call them when needed.
+
+Firmware operations can be specified by filling in a struct firmware_ops
+with appropriate callbacks and then registering it with register_firmware_ops()
+function::
+
+	void register_firmware_ops(const struct firmware_ops *ops)
+
+The ops pointer must be non-NULL. More information about struct firmware_ops
+and 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 to
+set 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 allow
+fallback 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);