From mboxrd@z Thu Jan  1 00:00:00 1970
From: =?UTF-8?q?Pali=20Roh=C3=A1r?= <pali.rohar@gmail.com>
Subject: [PATCH 4/5] arm: devtree: Read ATAGs structure from DT "/chosen/linux,atags" entry
Date: Mon,  6 Jul 2015 22:26:12 +0200
Message-ID: <1436214373-12969-5-git-send-email-pali.rohar@gmail.com>
References: <1436214373-12969-1-git-send-email-pali.rohar@gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: QUOTED-PRINTABLE
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <1436214373-12969-1-git-send-email-pali.rohar@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
To: Russell King <linux@arm.linux.org.uk>, Laura Abbott <lauraa@codeaurora.org>, Grant Likely <grant.likely@linaro.org>, Rob Herring <robherring2@gmail.com>, Will Deacon <will.deacon@arm.com>, Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>, Sebastian Reichel <sre@debian.org>, Pavel Machek <pavel@ucw.cz>, Tony Lindgren <tony@atomide.com>, =?UTF-8?q?Andreas=20F=C3=A4rber?= <afaerber@suse.de>
Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, =?UTF-8?q?Pali=20Roh=C3=A1r?= <pali.rohar@gmail.com>
List-Id: linux-omap@vger.kernel.org

With this patch when linux kernel is compiled with ARM_ATAG_DTB_COMPAT =
it
reads ATAGs structure from "/chosen/linux,atags" entry and store it int=
o
/proc/atags file. ATAGs structure is not parsed or evaluated, just kern=
el
exports it to userspace via procfs. It is needed for legacy userspace
application which expect some data from bootloader in /proc/atags file.
This patch keeps them running also on DT kernel if DT "/chosen/linux,at=
ags"
entry exists.

TODO: add documentation

Signed-off-by: Pali Roh=C3=A1r <pali.rohar@gmail.com>
---
 arch/arm/kernel/devtree.c |   24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/arch/arm/kernel/devtree.c b/arch/arm/kernel/devtree.c
index 7d82749..69ff048 100644
--- a/arch/arm/kernel/devtree.c
+++ b/arch/arm/kernel/devtree.c
@@ -20,6 +20,7 @@
 #include <linux/of_platform.h>
 #include <linux/smp.h>
 #include <linux/libfdt_env.h>
+#include <linux/libfdt.h>
=20
 #include <asm/cputype.h>
 #include <asm/setup.h>
@@ -29,6 +30,7 @@
 #include <asm/mach-types.h>
 #include <asm/system_info.h>
=20
+#include "atags.h"
=20
 #ifdef CONFIG_SMP
 extern struct of_cpu_method __cpu_method_of_table[];
@@ -208,6 +210,11 @@ const struct machine_desc * __init setup_machine_f=
dt(unsigned int dt_phys)
 	const struct machine_desc *mdesc, *mdesc_best =3D NULL;
 	unsigned long dt_root;
 	const u32 *rev;
+	void *dt_virt;
+#ifdef CONFIG_ARM_ATAG_DTB_COMPAT
+	const void *atags;
+	unsigned long dt_chosen;
+#endif
=20
 #ifdef CONFIG_ARCH_MULTIPLATFORM
 	DT_MACHINE_START(GENERIC_DT, "Generic DT based system")
@@ -216,7 +223,12 @@ const struct machine_desc * __init setup_machine_f=
dt(unsigned int dt_phys)
 	mdesc_best =3D &__mach_desc_GENERIC_DT;
 #endif
=20
-	if (!dt_phys || !early_init_dt_verify(phys_to_virt(dt_phys)))
+	if (!dt_phys)
+		return NULL;
+
+	dt_virt =3D phys_to_virt(dt_phys);
+
+	if (!early_init_dt_verify(dt_virt))
 		return NULL;
=20
 	dt_root =3D of_get_flat_dt_root();
@@ -254,5 +266,15 @@ const struct machine_desc * __init setup_machine_f=
dt(unsigned int dt_phys)
 	if (rev)
 		system_rev =3D fdt32_to_cpu(*rev);
=20
+#ifdef CONFIG_ARM_ATAG_DTB_COMPAT
+	/* Store DT /chosen/linux,atags into /proc/atags */
+	dt_chosen =3D fdt_path_offset(dt_virt, "/chosen");
+	if (dt_chosen >=3D 0) {
+		atags =3D of_get_flat_dt_prop(dt_chosen, "linux,atags", NULL);
+		if (atags)
+			save_atags(atags);
+	}
+#endif
+
 	return mdesc;
 }
--=20
1.7.9.5