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Subject[PATCH 2/3] clocksource: add DB8500 PRCMU Timer support
Date
This patch adds the DB8500 PRCMU Timer driver as a clocksource
and as sched_clock.

Signed-off-by: Mattias Wallin <mattias.wallin@stericsson.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
---
drivers/clocksource/Kconfig | 15 +++++
drivers/clocksource/Makefile | 1 +
drivers/clocksource/clksrc-db8500-prcmu.c | 89 +++++++++++++++++++++++++++++
include/linux/clksrc-db8500-prcmu.h | 17 ++++++
4 files changed, 122 insertions(+), 0 deletions(-)
create mode 100644 drivers/clocksource/clksrc-db8500-prcmu.c
create mode 100644 include/linux/clksrc-db8500-prcmu.h

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 96c9219..d7ee415 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -3,3 +3,18 @@ config CLKSRC_I8253

config CLKSRC_MMIO
bool
+
+config CLKSRC_DB8500_PRCMU
+ bool "Clocksource PRCMU Timer"
+ depends on MFD_DB8500_PRCMU
+ default y
+ help
+ Use the always on PRCMU Timer as clocksource
+
+config CLKSRC_DB8500_PRCMU_SCHED_CLOCK
+ bool "Clocksource PRCMU Timer sched_clock"
+ depends on (CLKSRC_DB8500_PRCMU && !NOMADIK_MTU_SCHED_CLOCK)
+ select HAVE_SCHED_CLOCK
+ default y
+ help
+ Use the always on PRCMU Timer as sched_clock
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index b995942..f2308ba 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -8,3 +8,4 @@ obj-$(CONFIG_SH_TIMER_MTU2) += sh_mtu2.o
obj-$(CONFIG_SH_TIMER_TMU) += sh_tmu.o
obj-$(CONFIG_CLKSRC_I8253) += i8253.o
obj-$(CONFIG_CLKSRC_MMIO) += mmio.o
+obj-$(CONFIG_CLKSRC_DB8500_PRCMU) += clksrc-db8500-prcmu.o
diff --git a/drivers/clocksource/clksrc-db8500-prcmu.c b/drivers/clocksource/clksrc-db8500-prcmu.c
new file mode 100644
index 0000000..07a4d1a
--- /dev/null
+++ b/drivers/clocksource/clksrc-db8500-prcmu.c
@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) ST-Ericsson SA 2011
+ *
+ * License Terms: GNU General Public License v2
+ * Author: Mattias Wallin <mattias.wallin@stericsson.com> for ST-Ericsson
+ * sched_clock implementation is based on:
+ * plat-nomadik/timer.c Linus Walleij <linus.walleij@stericsson.com>
+ *
+ * Clocksource DB8500 PRCMU Timer
+ * The PRCMU in the DB8500 chip has 5 timers which
+ * are available in an always-on power domain.
+ * Timer 4 is dedicated to our always-on clock source.
+ */
+#include <linux/clockchips.h>
+#include <linux/clksrc-db8500-prcmu.h>
+#include <asm/sched_clock.h>
+#include <mach/setup.h>
+#include <mach/db8500-regs.h>
+#include <mach/hardware.h>
+
+#define RATE_32K (32768)
+
+#define TIMER_MODE_CONTINOUS (0x1)
+#define TIMER_DOWNCOUNT_VAL (0xffffffff)
+
+/* PRCMU Timer 4 */
+#define PRCMU_TIMER_4_REF (prcmu_base + 0x450)
+#define PRCMU_TIMER_4_DOWNCOUNT (prcmu_base + 0x454)
+#define PRCMU_TIMER_4_MODE (prcmu_base + 0x458)
+
+static __iomem void *prcmu_base;
+
+#define SCHED_CLOCK_MIN_WRAP (131072) /* 2^32 / 32768 */
+
+static cycle_t clksrc_db8500_prcmu_read(struct clocksource *cs)
+{
+ u32 count, count2;
+
+ do {
+ count = readl(PRCMU_TIMER_4_DOWNCOUNT);
+ count2 = readl(PRCMU_TIMER_4_DOWNCOUNT);
+ } while (count2 != count);
+
+ /* Negate because the timer is a decrementing counter */
+ return ~count;
+}
+
+static struct clocksource clocksource_db8500_prcmu = {
+ .name = "clksrc-db8500-prcmu-timer4",
+ .rating = 300,
+ .read = clksrc_db8500_prcmu_read,
+ .shift = 10,
+ .mask = CLOCKSOURCE_MASK(32),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+#ifdef CONFIG_CS_DB8500_PRCMU_SCHED_CLOCK
+static DEFINE_CLOCK_DATA(cd);
+
+static void notrace clksrc_db8500_prcmu_update_sched_clock(void)
+{
+ u32 cyc = clksrc_db8500_prcmu_read(&clocksource_db8500_prcmu);
+ update_sched_clock(&cd, cyc, (u32)~0);
+}
+#endif
+
+void __init clksrc_db8500_prcmu_init(void)
+{
+ prcmu_base = __io_address(U8500_PRCMU_BASE);
+
+ /*
+ * The A9 sub system expects the timer to be configured as
+ * a continous looping timer.
+ * The PRCMU should configure it but if it for some reason
+ * don't we do it here.
+ */
+ if (readl(PRCMU_TIMER_4_MODE) != TIMER_MODE_CONTINOUS) {
+ writel(TIMER_MODE_CONTINOUS, PRCMU_TIMER_4_MODE);
+ writel(TIMER_DOWNCOUNT_VAL, PRCMU_TIMER_4_REF);
+ }
+#ifdef CONFIG_CS_DB8500_PRCMU_SCHED_CLOCK
+ init_sched_clock(&cd, clksrc_db8500_prcmu_update_sched_clock,
+ 32, RATE_32K);
+#endif
+ clocksource_calc_mult_shift(&clocksource_db8500_prcmu,
+ RATE_32K, SCHED_CLOCK_MIN_WRAP);
+ clocksource_register(&clocksource_db8500_prcmu);
+}
+
diff --git a/include/linux/clksrc-db8500-prcmu.h b/include/linux/clksrc-db8500-prcmu.h
new file mode 100644
index 0000000..42b8587
--- /dev/null
+++ b/include/linux/clksrc-db8500-prcmu.h
@@ -0,0 +1,17 @@
+/*
+ * Copyright (C) ST-Ericsson SA 2011
+ *
+ * License Terms: GNU General Public License v2
+ * Author: Mattias Wallin <mattias.wallin@stericsson.com>
+ *
+ */
+#ifndef __CLKSRC_DB8500_PRCMU_H
+#define __CLKSRC_DB8500_PRCMU_H
+
+#ifdef CONFIG_CLKSRC_DB8500_PRCMU
+void __init clksrc_db8500_prcmu_init(void);
+#else
+void __init clksrc_db8500_prcmu_init(void) {}
+#endif
+
+#endif
--
1.7.4.3


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