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@xxxxxxxx>
Cc: Colin Cross <ccross@xxxxxxxxxxx>
Cc: Eric Miao <eric.y.miao@xxxxxxxxx>
Cc: Erik Gilling <konkers@xxxxxxxxxxx>
Acked-by: "Hans J. Koch" <hjk@xxxxxxxxxxxx>
Cc: Imre Kaloz <kaloz@xxxxxxxxxxx>
Cc: Krzysztof Halasa <khc@xxxxxxxxx>
Cc: Kukjin Kim <kgene.kim@xxxxxxxxxxx>
Cc: Lennert Buytenhek <kernel@xxxxxxxxxxxxxx>
Cc: Linus Walleij <linus.walleij@xxxxxxxxxxxxxx>
Cc: linux-omap@xxxxxxxxxxxxxxx
Cc: Nicolas Pitre <nico@xxxxxxxxxxx>
Cc: Olof Johansson <olof@xxxxxxxxx>
Tested-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
Cc: Tony Lindgren <tony@xxxxxxxxxxx>
Reviewed-by: Viresh Kumar <viresh.kumar@xxxxxx>
Cc: Wan ZongShun <mcuos.com@xxxxxxxxx>
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
---
This is the version with cs->reg initialized.
drivers/Kconfig | 3 ++
drivers/clocksource/Kconfig | 2 +
drivers/clocksource/Makefile | 1 +
drivers/clocksource/mmio.c | 73 ++++++++++++++++++++++++++++++++++++++++++
include/linux/clocksource.h | 8 ++++
5 files changed, 87 insertions(+), 0 deletions(-)
create mode 100644 drivers/clocksource/Kconfig
create mode 100644 drivers/clocksource/mmio.c
diff --git a/drivers/Kconfig b/drivers/Kconfig
index 177c7d1..557a469 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -119,4 +119,7 @@ source "drivers/platform/Kconfig"
source "drivers/clk/Kconfig"
source "drivers/hwspinlock/Kconfig"
+
+source "drivers/clocksource/Kconfig"
+
endmenu
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
new file mode 100644
index 0000000..47f37b1
--- /dev/null
+++ b/drivers/clocksource/Kconfig
@@ -0,0 +1,2 @@
+config CLKSRC_MMIO
+ bool
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index be61ece..9b2ba29 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -6,3 +6,4 @@ obj-$(CONFIG_CS5535_CLOCK_EVENT_SRC) += cs5535-clockevt.o
obj-$(CONFIG_SH_TIMER_CMT) += sh_cmt.o
obj-$(CONFIG_SH_TIMER_MTU2) += sh_mtu2.o
obj-$(CONFIG_SH_TIMER_TMU) += sh_tmu.o
+obj-$(CONFIG_CLKSRC_MMIO) += mmio.o
diff --git a/drivers/clocksource/mmio.c b/drivers/clocksource/mmio.c
new file mode 100644
index 0000000..c0e2512
--- /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);
+}
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 94c1f38..a3558fd 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -341,4 +341,12 @@ static inline void update_vsyscall_tz(void)
extern void timekeeping_notify(struct clocksource *clock);
+extern cycle_t clocksource_mmio_readl_up(struct clocksource *);
+extern cycle_t clocksource_mmio_readl_down(struct clocksource *);
+extern cycle_t clocksource_mmio_readw_up(struct clocksource *);
+extern cycle_t clocksource_mmio_readw_down(struct clocksource *);
+
+extern int clocksource_mmio_init(void __iomem *, const char *,
+ unsigned long, int, unsigned, cycle_t (*)(struct clocksource *));
+
#endif /* _LINUX_CLOCKSOURCE_H */
--
1.7.4.4
--
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