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authorPawel Moll <pawel.moll@arm.com>2014-04-16 18:22:59 +0100
committerPawel Moll <pawel.moll@arm.com>2014-05-15 17:02:20 +0100
commit220e2a8d22cd57d5ec8111465923c6c25691394d (patch)
treeec0f82e350f4add4dddb542a9a76a14ab9d026fc /drivers/clocksource/versatile.c
parent5ee2b877793d89f1d73338d08af12f73fbbfed4a (diff)
downloadop-kernel-dev-220e2a8d22cd57d5ec8111465923c6c25691394d.zip
op-kernel-dev-220e2a8d22cd57d5ec8111465923c6c25691394d.tar.gz
clocksource: Sched clock source for Versatile Express
This patch adds a trival sched clock source using free running, 24MHz clocked counter present in the ARM Ltd. reference platforms (Versatile, RealView, Versatile Express) System Registers block. This code replaces the call in the VE machine code. Signed-off-by: Pawel Moll <pawel.moll@arm.com> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'drivers/clocksource/versatile.c')
-rw-r--r--drivers/clocksource/versatile.c40
1 files changed, 40 insertions, 0 deletions
diff --git a/drivers/clocksource/versatile.c b/drivers/clocksource/versatile.c
new file mode 100644
index 0000000..e4c50ad
--- /dev/null
+++ b/drivers/clocksource/versatile.c
@@ -0,0 +1,40 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * Copyright (C) 2014 ARM Limited
+ */
+
+#include <linux/clocksource.h>
+#include <linux/io.h>
+#include <linux/of_address.h>
+#include <linux/sched_clock.h>
+
+#define SYS_24MHZ 0x05c
+
+static void __iomem *versatile_sys_24mhz;
+
+static u32 notrace versatile_sys_24mhz_read(void)
+{
+ return readl(versatile_sys_24mhz);
+}
+
+static void __init versatile_sched_clock_init(struct device_node *node)
+{
+ void __iomem *base = of_iomap(node, 0);
+
+ if (!base)
+ return;
+
+ versatile_sys_24mhz = base + SYS_24MHZ;
+
+ setup_sched_clock(versatile_sys_24mhz_read, 32, 24000000);
+}
+CLOCKSOURCE_OF_DECLARE(versatile, "arm,vexpress-sysreg",
+ versatile_sched_clock_init);
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