linux-kernel - [PATCH v2 7/9] ARC: use fixed frequencies in arc_set_early_base

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Date:	Tue, 8 Mar 2016 17:56:10 +0530
From:	Vineet Gupta <Vineet.Gupta1@...opsys.com>
To:	<linux-snps-arc@...ts.infradead.org>
CC:	lkml <linux-kernel@...r.kernel.org>, Noam Camus <noamc@...hip.com>,
	Alexey Brodkin <Alexey.Brodkin@...opsys.com>,
	Rob Herring <robh@...nel.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Christian Ruppert <christian.ruppert@...tech.com>,
	Vineet Gupta <Vineet.Gupta1@...opsys.com>
Subject: [PATCH v2 7/9] ARC: use fixed frequencies in arc_set_early_base_baud()

From: Alexey Brodkin <abrodkin@...opsys.com>

UARTs usually have fixed clock so we're switching to use of
constant values instead of something derived from core clock
frequency.

Among other things this will allow us to get rid of
arc_{get|set}_core_freq() and switch to generic clock
framework later on.

Cc: Christian Ruppert <christian.ruppert@...tech.com>
Signed-off-by: Alexey Brodkin <abrodkin@...opsys.com>
Signed-off-by: Vineet Gupta <vgupta@...opsys.com>
---
Changes v1 -> v2
 - Base baud TB10x needs to be 166.66 not 166.67	[Christian]

v1:
 - http://lists.infradead.org/pipermail/linux-snps-arc/2016-February/000453.html

Signed-off-by: Vineet Gupta <vgupta@...opsys.com>
---
 arch/arc/kernel/devtree.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/arc/kernel/devtree.c b/arch/arc/kernel/devtree.c
index 7e844fd8213f..fecbc96df828 100644
--- a/arch/arc/kernel/devtree.c
+++ b/arch/arc/kernel/devtree.c
@@ -28,14 +28,12 @@ unsigned int __init arc_early_base_baud(void)
 
 static void __init arc_set_early_base_baud(unsigned long dt_root)
 {
-	unsigned int core_clk = arc_get_core_freq();
-
 	if (of_flat_dt_is_compatible(dt_root, "abilis,arc-tb10x"))
-		arc_base_baud = core_clk/3;
+		arc_base_baud = 166666666;	/* Fixed 166.6MHz clk (TB10x) */
 	else if (of_flat_dt_is_compatible(dt_root, "snps,arc-sdp"))
 		arc_base_baud = 33333333;	/* Fixed 33MHz clk (AXS10x) */
 	else
-		arc_base_baud = core_clk;
+		arc_base_baud = 50000000;	/* Fixed default 50MHz */
 }
 #else
 #define arc_set_early_base_baud(dt_root)
-- 
2.5.0