[PATCH 02/27] console: Unify console_simple.c and pbl/console.c

Sam Ravnborg sam at ravnborg.org
Thu Jun 14 21:58:05 PDT 2018


Hi Andrey.

> +
> +/**
> + * __console_get_default - Return default output console
> + *
> + * Internal function used to determine which console to use for early
> + * output. It has the following two use-cases:
> + *
> + *   1. PBL, where it falls back onto console_ll and whatever it is
> + *      set up to (either putc_ll or custome callback set with
> + *      pbl_set_putc())
> + *
> + *   2. CONSOLE_SIMPLE, where it falls back onto console_ll (which in
> + *      this case always boils down to a putc_ll() call) until first
> + *      (and only) console is registered via console_register().
> + */
> +struct console_device *__console_get_default(void)

If it is used as internal only then it should be static.
(Have not read the the remaining patches)

> +{
> +	/*
> +	 * Doing on-demand initialization here as opposed to in the
> +	 * definition of console_ll above has that advantage that on
> +	 * some architecutres (e.g. AArch64) it allows us to avoid
> +	 * additional relocation and makes it possible to use console
> +	 * infrastructure before any relocation happens
> +	 */
> +	if (unlikely(!console_ll.putc))
> +		console_ll.putc = __console_ll_putc;
> +
> +	if (IS_ENABLED(__PBL__) || !console)
> +		return &console_ll;
> +
> +	return console;
> +}
> +
> +/**
> + * __console_set_putc - Early console initalization helper
> + *
> + * @cdev:	Console device to initialize
> + * @putcf:	putc() implementation to be used for this console
> + * @ctx:	Context to pass to putc()
> + *
> + * Internal function used to initialize early/trivial console devices
> + * capable of only outputting a single character
> + */
> +void __console_set_putc(struct console_device *cdev,
> +			putc_func_t putcf, void *ctx)
Likewise, and so on for the reimaining __xxx functions.


> +{
> +	cdev->putc = (void *)putcf;
> +	cdev->ctx = ctx;
> +}
> +
> +/**
> + * __cdev_putc - Internal .putc() callback dispatcher
> + *
> + * @cdev:	Console device to use
> + * @c:		Character to print
> + *
> + * Internal .putc() callback dispatcher needed to correctly select
> + * which context to pass.
> + *
> + * This is needed becuase when being used in PBL in conjunction with
> + * pbl_set_putc(), .putc() callback is expecting to receive a void *
> + * context that was registered earlier.
> + *
> + * In the "normal" world, however all of the .putc() callback are
> + * written with expectation of receiving struct console_device * as a
> + * first argument.
> + *
> + * Accomodation of both of those use-cases is the purpoese of this
> + * function
> + */
> +void __cdev_putc(struct console_device *cdev, char c)
> +{
> +	void *ctx = cdev->ctx ? : cdev;
Looks strange to me.
What is ctx assigned in the "true" case?
Maybe there is some subtle C rule that I have missed/forgot.
Point is, if this is valid code it may also make other puzzeled.

> +
> +	cdev->putc(ctx, c);
> +}
> +
> +/**
> + * __console_putc - Internal high-level putc() implementation
> + *
> + * @cdev:	Console device to use
> + * @c:		Character to print
> + *
> + * Internal high-level putc() implementation based on __cdev_putc()
> + * that performs correct '\n' -> '\n\r' substitution.
> + */
> +void __console_putc(struct console_device *cdev, char c)
> +{
> +	__cdev_putc(cdev, c);
> +	if (c == '\n')
> +		__cdev_putc(cdev, '\r');
> +}
> diff --git a/pbl/console.c b/pbl/console.c
> index 75576ec79..c1c3e1dde 100644
> --- a/pbl/console.c
> +++ b/pbl/console.c
> @@ -2,12 +2,7 @@
>  #include <debug_ll.h>
>  #include <linux/err.h>
>  
> -/*
> - * Put these in the data section so that they survive the clearing of the
> - * BSS segment.
> - */
> -static __attribute__ ((section(".data"))) putc_func_t __putc;
> -static __attribute__ ((section(".data"))) void *putc_ctx;
> +extern struct console_device console_ll;

I mentioned these in previous mail, and I see them gone now. OK.

	Sam



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