linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Oleksandr Tyshchenko <olekstysh@gmail.com>
To: linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: julien.grall@arm.com, horms@verge.net.au, magnus.damm@gmail.com,
	linux@armlinux.org.uk,
	Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Subject: [PATCH] ARM: mach-shmobile: Don't configure ARCH timer if PSCI is enabled
Date: Wed, 17 Apr 2019 20:10:40 +0300	[thread overview]
Message-ID: <1555521040-16706-1-git-send-email-olekstysh@gmail.com> (raw)

From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>

If CONFIG_PSCI is enabled then most likely we are running on
PSCI-enabled U-Boot which, we assume, has already taken care of
configuring ARCH timer stuff before switching to non-secure mode.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>

---
A bit of context here...

We are highly interested in Renesas "Stout" board support (r8a7790)
in Xen hypervisor. The reason is to have fully supported HW for
performing "OSSTEST" (Xen automatic test system) on ARM32.

To reach that target we need a "generic way" for the secondary CPU cores
bring up and switching them to non-secure hyp mode.
So, the PSCI as a generic well-known way to bring up CPUs, was chosen
for that purpose. 

You can find corresponding patches for U-Boot here:
http://u-boot.10912.n7.nabble.com/PATCH-0-3-PSCI-support-for-r8a7790-SoC-Lager-Stout-boards-td357352.html

You can find corresponding patches for Xen hypervisor here:
https://www.mail-archive.com/xen-devel@lists.xenproject.org/msg43332.html

To sumarize:
Together with enabling CONFIG_PSCI in shmobile_defconfig, current patch
is a minimal required change needed to run mainline Linux on top of
PSCI-enabled U-Boot.
There is no need to modify device tree. U-Boot will take care of inserting
proper "enable-method" strings in CPU nodes.

---
 arch/arm/mach-shmobile/setup-rcar-gen2.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-shmobile/setup-rcar-gen2.c b/arch/arm/mach-shmobile/setup-rcar-gen2.c
index eea60b2..bac4490 100644
--- a/arch/arm/mach-shmobile/setup-rcar-gen2.c
+++ b/arch/arm/mach-shmobile/setup-rcar-gen2.c
@@ -32,7 +32,7 @@ static const struct of_device_id cpg_matches[] __initconst = {
 	{ /* sentinel */ }
 };
 
-static unsigned int __init get_extal_freq(void)
+static unsigned int __init __maybe_unused get_extal_freq(void)
 {
 	const struct of_device_id *match;
 	struct device_node *cpg, *extal;
@@ -60,6 +60,12 @@ static unsigned int __init get_extal_freq(void)
 
 void __init rcar_gen2_timer_init(void)
 {
+/*
+ * If CONFIG_PSCI is enabled then most likely we are running on PSCI-enabled
+ * U-Boot which, we assume, has already taken care of configuring ARCH timer
+ * stuff before switching to non-secure mode.
+ */
+#if !defined(CONFIG_ARM_PSCI)
 	void __iomem *base;
 	u32 freq;
 
@@ -101,6 +107,7 @@ void __init rcar_gen2_timer_init(void)
 	}
 
 	iounmap(base);
+#endif /* #if !defined(CONFIG_ARM_PSCI) */
 
 	of_clk_init(NULL);
 	timer_probe();
-- 
2.7.4


             reply	other threads:[~2019-04-17 17:11 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-17 17:10 Oleksandr Tyshchenko [this message]
2019-04-18  7:14 ` [PATCH] ARM: mach-shmobile: Don't configure ARCH timer if PSCI is enabled Biju Das
2019-04-18 10:35   ` Oleksandr
2019-04-18  9:32 ` Julien Grall
2019-04-18 11:15   ` Oleksandr
2019-04-24 12:31     ` Julien Grall
2019-04-26 19:51       ` Oleksandr

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1555521040-16706-1-git-send-email-olekstysh@gmail.com \
    --to=olekstysh@gmail.com \
    --cc=horms@verge.net.au \
    --cc=julien.grall@arm.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-renesas-soc@vger.kernel.org \
    --cc=linux@armlinux.org.uk \
    --cc=magnus.damm@gmail.com \
    --cc=oleksandr_tyshchenko@epam.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).