u5500: add MTIMER clocksource

ST-Ericsson ID: 368260
ST-Ericsson Linux next: NA
ST-Ericsson FOSS-OUT ID: Trivial

Depends-On: I5307cb7f58fdf890896d641a8e4f49098a90b68e

Change-Id: I9ef4ff1c63f6ec9293ece4013f13cf3caa707d9d
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Reviewed-on: http://gerrit.lud.stericsson.com/gerrit/34307
Reviewed-by: QATOOLS
Reviewed-by: QABUILD

7 files changed, 100 insertions, 4 deletions

diff --git a/arch/arm/mach-ux500/cpu-db5500.c b/arch/arm/mach-ux500/cpu-db5500.c
index 9518c6db7f7..ea4fbbb1fc6 100644
--- a/arch/arm/mach-ux500/cpu-db5500.c
+++ b/arch/arm/mach-ux500/cpu-db5500.c
@@ -41,6 +41,7 @@ static struct map_desc u5500_io_desc[] __initdata = {
 	__IO_DEV_DESC(U5500_MTU1_BASE, SZ_4K),
 	__IO_DEV_DESC(U5500_SCU_BASE, SZ_4K),
 	__IO_DEV_DESC(U5500_RTC_BASE, SZ_4K),
+	__IO_DEV_DESC(U5500_MTIMER_BASE, SZ_4K),
 	__IO_DEV_DESC(U5500_BACKUPRAM0_BASE, SZ_8K),
 	__MEM_DEV_DESC(U5500_BOOT_ROM_BASE, SZ_1M),
 
diff --git a/arch/arm/mach-ux500/include/mach/db5500-regs.h b/arch/arm/mach-ux500/include/mach/db5500-regs.h
index 870c3ff574c..f853c20587a 100644
--- a/arch/arm/mach-ux500/include/mach/db5500-regs.h
+++ b/arch/arm/mach-ux500/include/mach/db5500-regs.h
@@ -66,6 +66,7 @@
 #define U5500_PRCMU_TIMER_4_BASE (U5500_PER4_BASE + 0x07450)
 #define U5500_MSP1_BASE		(U5500_PER4_BASE + 0x9000)
 #define U5500_GPIO2_BASE	(U5500_PER4_BASE + 0xA000)
+#define U5500_MTIMER_BASE	(U5500_PER4_BASE + 0xC000)
 #define U5500_CDETECT_BASE	(U5500_PER4_BASE + 0xF000)
 #define U5500_PRCMU_TCDM_BASE	(U5500_PER4_BASE + 0x18000)
 #define U5500_PRCMU_TCPM_BASE	(U5500_PER4_BASE + 0x10000)
diff --git a/arch/arm/mach-ux500/timer.c b/arch/arm/mach-ux500/timer.c
index c395f5c8992..df1945b1991 100644
--- a/arch/arm/mach-ux500/timer.c
+++ b/arch/arm/mach-ux500/timer.c
@@ -7,6 +7,7 @@
 #include <linux/io.h>
 #include <linux/errno.h>
 #include <linux/clksrc-dbx500-prcmu.h>
+#include <linux/clksrc-db5500-mtimer.h>
 
 #include <asm/localtimer.h>
 
@@ -67,12 +68,18 @@ static void __init ux500_timer_init(void)
 	 * depending on delay which is not yet calibrated. RTC-RTT is in the
 	 * always-on powerdomain and is used as clockevent instead of twd when
 	 * sleeping.
-	 * The PRCMU timer 4(3 for DB5500) register a clocksource and
-	 * sched_clock with higher rating then MTU since is always-on.
 	 *
+	 * The PRCMU timer 4 (3 for DB5500) registers a clocksource and
+	 * sched_clock with higher rating than the MTU since it is
+	 * always-on.
+	 *
+	 * On DB5500, the MTIMER is the best clocksource since, unlike the
+	 * PRCMU timer, it doesn't occasionally go backwards.
 	 */
 
 	nmdk_timer_init();
+	if (cpu_is_u5500())
+		db5500_mtimer_init(__io_address(U5500_MTIMER_BASE));
 	clksrc_dbx500_prcmu_init(prcmu_timer_base);
 
 #ifdef CONFIG_UX500_CONTEXT
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 206f35f7d8c..75935af43f2 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -7,13 +7,30 @@ config CLKSRC_MMIO
 config CLKSRC_DBX500_PRCMU
 	bool "Clocksource PRCMU Timer"
 	depends on UX500_SOC_DB5500 || UX500_SOC_DB8500
-	default y
+	default y if UX500_SOC_DB8500
 	help
 	  Use the always on PRCMU Timer as clocksource
 
 config CLKSRC_DBX500_PRCMU_SCHED_CLOCK
 	bool "Clocksource PRCMU Timer sched_clock"
-	depends on (CLKSRC_DBX500_PRCMU && !NOMADIK_MTU_SCHED_CLOCK)
+	depends on (CLKSRC_DBX500_PRCMU && !NOMADIK_MTU_SCHED_CLOCK && \
+			!CLKSRC_DB5500_MTIMER_SCHED_CLOCK)
+	select HAVE_SCHED_CLOCK
+	default y
+	help
+	  Use the always on PRCMU Timer as sched_clock
+
+config CLKSRC_DB5500_MTIMER
+	bool "Clocksource MTIMER"
+	depends on UX500_SOC_DB5500
+	default y
+	help
+	  Use the always on MTIMER as clocksource
+
+config CLKSRC_DB5500_MTIMER_SCHED_CLOCK
+	bool "Clocksource MTIMER sched_clock"
+	depends on (CLKSRC_DB5500_MTIMER && !NOMADIK_MTU_SCHED_CLOCK && \
+			!CLKSRC_DBX500_PRCMU_SCHED_CLOCK)
 	select HAVE_SCHED_CLOCK
 	default y
 	help
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 285e9a3a61f..027e71d6d05 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -9,3 +9,4 @@ obj-$(CONFIG_SH_TIMER_TMU)	+= sh_tmu.o
 obj-$(CONFIG_CLKSRC_I8253)	+= i8253.o
 obj-$(CONFIG_CLKSRC_MMIO)	+= mmio.o
 obj-$(CONFIG_CLKSRC_DBX500_PRCMU)	+= clksrc-dbx500-prcmu.o
+obj-$(CONFIG_CLKSRC_DB5500_MTIMER)	+= db5500-mtimer.o
diff --git a/drivers/clocksource/db5500-mtimer.c b/drivers/clocksource/db5500-mtimer.c
new file mode 100644
index 00000000000..641279707a8
--- /dev/null
+++ b/drivers/clocksource/db5500-mtimer.c
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) ST-Ericsson SA 2011
+ *
+ * License Terms: GNU General Public License v2
+ */
+
+#include <linux/io.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/clockchips.h>
+#include <linux/clksrc-db5500-mtimer.h>
+
+#include <asm/sched_clock.h>
+
+#define MTIMER_PRIMARY_COUNTER		0x18
+
+static void __iomem *db5500_mtimer_base;
+
+#ifdef CONFIG_CLKSRC_DB5500_MTIMER_SCHED_CLOCK
+static DEFINE_CLOCK_DATA(cd);
+
+unsigned long long notrace sched_clock(void)
+{
+	u32 cyc;
+
+	if (unlikely(!db5500_mtimer_base))
+		return 0;
+
+	cyc = readl_relaxed(db5500_mtimer_base + MTIMER_PRIMARY_COUNTER);
+
+	return cyc_to_sched_clock(&cd, cyc, (u32)~0);
+}
+
+static void notrace db5500_mtimer_update_sched_clock(void)
+{
+	u32 cyc = readl_relaxed(db5500_mtimer_base + MTIMER_PRIMARY_COUNTER);
+	update_sched_clock(&cd, cyc, (u32)~0);
+}
+#endif
+
+void __init db5500_mtimer_init(void __iomem *base)
+{
+	db5500_mtimer_base = base;
+
+	clocksource_mmio_init(base + MTIMER_PRIMARY_COUNTER, "mtimer", 32768,
+			      400, 32, clocksource_mmio_readl_up);
+
+#ifdef CONFIG_CLKSRC_DB5500_MTIMER_SCHED_CLOCK
+	init_sched_clock(&cd, db5500_mtimer_update_sched_clock,
+			 32, 32768);
+#endif
+}
diff --git a/include/linux/clksrc-db5500-mtimer.h b/include/linux/clksrc-db5500-mtimer.h
new file mode 100644
index 00000000000..3112c7f2709
--- /dev/null
+++ b/include/linux/clksrc-db5500-mtimer.h
@@ -0,0 +1,17 @@
+/*
+ * Copyright (C) ST-Ericsson SA 2011
+ *
+ * License Terms: GNU General Public License v2
+ */
+#ifndef __CLKSRC_DB5500_MTIMER_H
+#define __CLKSRC_DB5500_MTIMER_H
+
+#include <linux/io.h>
+
+#ifdef CONFIG_CLKSRC_DB5500_MTIMER
+void db5500_mtimer_init(void __iomem *base);
+#else
+static inline void db5500_mtimer_init(void __iomem *base) {}
+#endif
+
+#endif