[U-Boot] [PATCH v2 1/5] lib: Add wait_for_bit

[Marek Vasut <marex@denx.de>]

On Wednesday, December 16, 2015 at 10:58:38 PM, Mateusz Kulikowski wrote:
> Add function to poll register waiting for specific bit(s).
> Similar functions are implemented in few drivers - they are almost
> identical and can be generalized.
> 
> Signed-off-by: Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
> ---
> 
>  include/wait_bit.h | 35 +++++++++++++++++++++++++++++++++++
>  lib/Makefile       |  1 +
>  lib/wait_bit.c     | 45 +++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 81 insertions(+)
>  create mode 100644 include/wait_bit.h
>  create mode 100644 lib/wait_bit.c
> 
> diff --git a/include/wait_bit.h b/include/wait_bit.h
> new file mode 100644
> index 0000000..052a09b
> --- /dev/null
> +++ b/include/wait_bit.h
> @@ -0,0 +1,35 @@
> +/*
> + * Wait for bit with timeout and ctrlc
> + *
> + * (C) Copyright 2015 Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
> + *
> + * SPDX-License-Identifier:	GPL-2.0+
> + */
> +
> +#ifndef __WAIT_BIT_H
> +#define __WAIT_BIT_H
> +
> +/**
> + * wait_for_bit()	waits for bit set/cleared in register
> + *
> + * Function polls register waiting for specific bit(s) change
> + * (either 0->1 or 1->0). It can fail under two conditions:
> + * - Timeout
> + * - User interaction (CTRL-C)
> + * Function succeeds only if all bits of masked register are set/cleared
> + * (depending on set option).
> + *
> + * @param prefix	Prefix added to timeout messagge (message visible only
> + *			with debug enabled)
> + * @param reg		Register that will be read (using readl())
> + * @param mask		Bit(s) of register that must be active
> + * @param set		Selects wait condition (bit set or clear)
> + * @param timeout	Timeout (in miliseconds)
> + * @param breakable	Enables CTRL-C interruption
> + * @return		0 on success, -ETIMEDOUT or -EINTR on failure
> + */
> +int wait_for_bit(const char *prefix, const u32 *reg, const u32 mask,
> +		 const bool set, const unsigned int timeout,
> +		 const bool breakable);
> +
> +#endif
> diff --git a/lib/Makefile b/lib/Makefile
> index 1f1ff6f..6fe3ab5 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -81,6 +81,7 @@ obj-y += time.o
>  obj-$(CONFIG_TRACE) += trace.o
>  obj-$(CONFIG_LIB_UUID) += uuid.o
>  obj-$(CONFIG_LIB_RAND) += rand.o
> +obj-y += wait_bit.o
> 
>  ifdef CONFIG_SPL_BUILD
>  # SPL U-Boot may use full-printf, tiny-printf or none at all
> diff --git a/lib/wait_bit.c b/lib/wait_bit.c
> new file mode 100644
> index 0000000..ac35f68
> --- /dev/null
> +++ b/lib/wait_bit.c
> @@ -0,0 +1,45 @@
> +/*
> + * Wait for bit interruptible by timeout or ctrlc
> + *
> + * (C) Copyright 2015 Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
> + *
> + * SPDX-License-Identifier:	GPL-2.0+
> + */
> +
> +#include <common.h>
> +#include <console.h>
> +#include <asm/io.h>
> +#include <asm/errno.h>
> +
> +int wait_for_bit(const char *prefix, const u32 *reg, const u32 mask,
> +		 const bool set, const unsigned int timeout,
> +		 const bool breakable)
> +{

I wonder, what would happen if you stuffed this function into the header
file altogether ? I think this would allow the compiler to do interprocedure
optimalization on whichever file this would be included into. I wonder if
that would have any impact on the resulting code size.