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authorRussell King <rmk+kernel@arm.linux.org.uk>2011-05-08 17:06:52 +0400
committerRussell King <rmk+kernel@arm.linux.org.uk>2011-05-23 21:04:51 +0400
commit442c8176d2efa468577738e3a99a6e051f6e8e55 (patch)
treefcf309e5f23b60b96e95ef22d70bb5f0e473c512 /drivers/clocksource/mmio.c
parent1ba4c3cb171d9899a3eaa2e45fa171e0704c1377 (diff)
downloadlinux-442c8176d2efa468577738e3a99a6e051f6e8e55.tar.xz
clocksource: add common mmio clocksource
Add a generic mmio clocksource, covering both 32-bit and 16-bit register access sizes, for up or down counters. This can be used to easily create clocksources for simple counter-based implementations. Cc: Alessandro Rubini <rubini@unipv.it> Cc: Colin Cross <ccross@android.com> Cc: Eric Miao <eric.y.miao@gmail.com> Cc: Erik Gilling <konkers@android.com> Acked-by: "Hans J. Koch" <hjk@hansjkoch.de> Cc: Imre Kaloz <kaloz@openwrt.org> Cc: Krzysztof Halasa <khc@pm.waw.pl> Cc: Kukjin Kim <kgene.kim@samsung.com> Cc: Lennert Buytenhek <kernel@wantstofly.org> Cc: Linus Walleij <linus.walleij@stericsson.com> Cc: linux-omap@vger.kernel.org Acked-by: Nicolas Pitre <nico@fluxnic.net> Cc: Olof Johansson <olof@lixom.net> Tested-by: Sascha Hauer <s.hauer@pengutronix.de> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Tony Lindgren <tony@atomide.com> Reviewed-by: Viresh Kumar <viresh.kumar@st.com> Cc: Wan ZongShun <mcuos.com@gmail.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'drivers/clocksource/mmio.c')
-rw-r--r--drivers/clocksource/mmio.c73
1 files changed, 73 insertions, 0 deletions
diff --git a/drivers/clocksource/mmio.c b/drivers/clocksource/mmio.c
new file mode 100644
index 000000000000..c0e25125a55e
--- /dev/null
+++ b/drivers/clocksource/mmio.c
@@ -0,0 +1,73 @@
+/*
+ * Generic MMIO clocksource support
+ *
+ * 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.
+ */
+#include <linux/clocksource.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+
+struct clocksource_mmio {
+ void __iomem *reg;
+ struct clocksource clksrc;
+};
+
+static inline struct clocksource_mmio *to_mmio_clksrc(struct clocksource *c)
+{
+ return container_of(c, struct clocksource_mmio, clksrc);
+}
+
+cycle_t clocksource_mmio_readl_up(struct clocksource *c)
+{
+ return readl_relaxed(to_mmio_clksrc(c)->reg);
+}
+
+cycle_t clocksource_mmio_readl_down(struct clocksource *c)
+{
+ return ~readl_relaxed(to_mmio_clksrc(c)->reg);
+}
+
+cycle_t clocksource_mmio_readw_up(struct clocksource *c)
+{
+ return readw_relaxed(to_mmio_clksrc(c)->reg);
+}
+
+cycle_t clocksource_mmio_readw_down(struct clocksource *c)
+{
+ return ~(unsigned)readw_relaxed(to_mmio_clksrc(c)->reg);
+}
+
+/**
+ * clocksource_mmio_init - Initialize a simple mmio based clocksource
+ * @base: Virtual address of the clock readout register
+ * @name: Name of the clocksource
+ * @hz: Frequency of the clocksource in Hz
+ * @rating: Rating of the clocksource
+ * @bits: Number of valid bits
+ * @read: One of clocksource_mmio_read*() above
+ */
+int __init clocksource_mmio_init(void __iomem *base, const char *name,
+ unsigned long hz, int rating, unsigned bits,
+ cycle_t (*read)(struct clocksource *))
+{
+ struct clocksource_mmio *cs;
+
+ if (bits > 32 || bits < 16)
+ return -EINVAL;
+
+ cs = kzalloc(sizeof(struct clocksource_mmio), GFP_KERNEL);
+ if (!cs)
+ return -ENOMEM;
+
+ cs->reg = base;
+ cs->clksrc.name = name;
+ cs->clksrc.rating = rating;
+ cs->clksrc.read = read;
+ cs->clksrc.mask = CLOCKSOURCE_MASK(bits);
+ cs->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS;
+
+ return clocksource_register_hz(&cs->clksrc, hz);
+}