Subject: [PATCH 2/9] ARM: sunxi: quirk support

From: [email-masked] (Maxime Ripard)
Date: Sun, 3 Aug 2014 14:42:11 +0200

On Thu, Jul 31, 2014 at 06:28:05PM -0300, Emilio L?pez wrote:
> Currently, some hardware revisions of sunxi SoCs need special care on
> some blocks because of hardware differences and/or bugs. Unfortunately,
> it is unfeasible to account for these issues directly when writing the
> device tree, as SoC revision can vary between different units of the
> same device. This commit introduces a place to adjust DT compatibles
> as needed to work around said issues before devices are probed. To
> demonstrate usage, two quirks are added for the PLL2 and audio codec
> on sun4i.
> 
> Signed-off-by: Emilio L?pez <[email-masked]>
> ---
>  arch/arm/mach-sunxi/Makefile |  2 +-
>  arch/arm/mach-sunxi/quirks.c | 82 ++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 83 insertions(+), 1 deletion(-)
>  create mode 100644 arch/arm/mach-sunxi/quirks.c
> 
> diff --git a/arch/arm/mach-sunxi/Makefile b/arch/arm/mach-sunxi/Makefile
> index 589239b..7c13f99 100644
> --- a/arch/arm/mach-sunxi/Makefile
> +++ b/arch/arm/mach-sunxi/Makefile
> @@ -1,2 +1,2 @@
> -obj-$(CONFIG_ARCH_SUNXI) += sunxi.o sunxi-soc-id.o
> +obj-$(CONFIG_ARCH_SUNXI) += sunxi.o sunxi-soc-id.o quirks.o
>  obj-$(CONFIG_SMP) += platsmp.o
> diff --git a/arch/arm/mach-sunxi/quirks.c b/arch/arm/mach-sunxi/quirks.c
> new file mode 100644
> index 0000000..99cdaa0
> --- /dev/null
> +++ b/arch/arm/mach-sunxi/quirks.c
> @@ -0,0 +1,82 @@
> +/*
> + * Runtime quirk handling for sunxi SoCs
> + *
> + * Copyright 2014 Emilio L?pez
> + *
> + * Emilio L?pez <[email-masked]>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/of.h>
> +#include <linux/slab.h>
> +#include <linux/string.h>
> +
> +#include "sunxi-soc-id.h"
> +
> +static int __init update_compatible_string(const char *oldc, const char *newc)
> +{
> +	int count = 0;
> +	struct property *newprop;
> +	size_t newlen = strlen(newc);
> +	struct device_node *np = NULL;
> +
> +	for_each_compatible_node(np, NULL, oldc) {
> +		newprop = kzalloc(sizeof(*newprop), GFP_KERNEL);
> +		if (!newprop)
> +			return -ENOMEM;
> +
> +		newprop->name = kstrdup("compatible", GFP_KERNEL);
> +		newprop->value = kstrdup(newc, GFP_KERNEL);
> +		newprop->length = newlen;
> +
> +		if (!newprop->name || !newprop->value) {
> +			kfree(newprop);
> +			return -ENOMEM;
> +		}
> +
> +		of_update_property(np, newprop);
> +		count++;
> +	}
> +
> +	return count;
> +}
> +
> +static void __init sun4i_pll2_quirk(void)
> +{
> +	/* Only revision A is affected */
> +	if (sunxi_soc_revision() != 'A')
> +		return;
> +
> +	WARN_ON(!update_compatible_string("allwinner,sun4i-a10-b-pll2",
> +					  "allwinner,sun4i-a10-a-pll2"));
> +}
> +
> +static void __init sun4i_codec_quirk(void)
> +{
> +	/* Only revision A is affected */
> +	if (sunxi_soc_revision() != 'A')
> +		return;
> +
> +	WARN_ON(!update_compatible_string("allwinner,sun4i-a10-b-codec",
> +					  "allwinner,sun4i-a10-a-codec"));
> +}
> +
> +static int __init sunxi_apply_quirks(void)
> +{
> +	if (of_machine_is_compatible("allwinner,sun4i-a10")) {
> +		sun4i_pll2_quirk();
> +		sun4i_codec_quirk();
> +	}
> +
> +	return 0;
> +}
> +postcore_initcall(sunxi_apply_quirks)

Have you tested it? My guess is that it wolud have to run *much*
sooner, before of_platform_populate to be effective.

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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