summaryrefslogtreecommitdiff
path: root/drivers/clocksource/clksrc-dbx500-prcmu.c
diff options
context:
space:
mode:
authorMattias Wallin <mattias.wallin@stericsson.com>2011-05-27 10:30:12 +0200
committerLinus Walleij <linus.walleij@linaro.org>2011-09-22 15:42:57 +0200
commit489bccea6334514a8e13436f10d0a274777bf17a (patch)
tree16ef60894e87bc95e1e44e975667325bb46f6679 /drivers/clocksource/clksrc-dbx500-prcmu.c
parentcba13830d3fcb1e025e224c496a10515a39a7f80 (diff)
clocksource: add DBX500 PRCMU Timer support
This patch adds the DBX500 PRCMU Timer driver as a clocksource and as sched_clock. Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Mattias Wallin <mattias.wallin@stericsson.com> Signed-off-by: Jonas Aaberg <jonas.aberg@stericsson.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'drivers/clocksource/clksrc-dbx500-prcmu.c')
-rw-r--r--drivers/clocksource/clksrc-dbx500-prcmu.c104
1 files changed, 104 insertions, 0 deletions
diff --git a/drivers/clocksource/clksrc-dbx500-prcmu.c b/drivers/clocksource/clksrc-dbx500-prcmu.c
new file mode 100644
index 000000000000..0ac5093a053a
--- /dev/null
+++ b/drivers/clocksource/clksrc-dbx500-prcmu.c
@@ -0,0 +1,104 @@
+/*
+ * Copyright (C) ST-Ericsson SA 2011
+ *
+ * License Terms: GNU General Public License v2
+ * Author: Mattias Wallin <mattias.wallin@stericsson.com> for ST-Ericsson
+ * Author: Sundar Iyer for ST-Ericsson
+ * sched_clock implementation is based on:
+ * plat-nomadik/timer.c Linus Walleij <linus.walleij@stericsson.com>
+ *
+ * DBx500-PRCMU Timer
+ * The PRCMU has 5 timers which are available in a always-on
+ * power domain. We use the Timer 4 for our always-on clock
+ * source on DB8500 and Timer 3 on DB5500.
+ */
+#include <linux/clockchips.h>
+#include <linux/clksrc-dbx500-prcmu.h>
+
+#include <asm/sched_clock.h>
+
+#include <mach/setup.h>
+#include <mach/hardware.h>
+
+#define RATE_32K 32768
+
+#define TIMER_MODE_CONTINOUS 0x1
+#define TIMER_DOWNCOUNT_VAL 0xffffffff
+
+#define PRCMU_TIMER_REF 0
+#define PRCMU_TIMER_DOWNCOUNT 0x4
+#define PRCMU_TIMER_MODE 0x8
+
+#define SCHED_CLOCK_MIN_WRAP 131072 /* 2^32 / 32768 */
+
+void __iomem *clksrc_dbx500_timer_base;
+
+static cycle_t clksrc_dbx500_prcmu_read(struct clocksource *cs)
+{
+ u32 count, count2;
+
+ do {
+ count = readl(clksrc_dbx500_timer_base +
+ PRCMU_TIMER_DOWNCOUNT);
+ count2 = readl(clksrc_dbx500_timer_base +
+ PRCMU_TIMER_DOWNCOUNT);
+ } while (count2 != count);
+
+ /* Negate because the timer is a decrementing counter */
+ return ~count;
+}
+
+static struct clocksource clocksource_dbx500_prcmu = {
+ .name = "dbx500-prcmu-timer",
+ .rating = 300,
+ .read = clksrc_dbx500_prcmu_read,
+ .shift = 10,
+ .mask = CLOCKSOURCE_MASK(32),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+#ifdef CONFIG_CLKSRC_DBX500_PRCMU_SCHED_CLOCK
+static DEFINE_CLOCK_DATA(cd);
+
+unsigned long long notrace sched_clock(void)
+{
+ u32 cyc;
+
+ if (unlikely(!clksrc_dbx500_timer_base))
+ return 0;
+
+ cyc = clksrc_dbx500_prcmu_read(&clocksource_dbx500_prcmu);
+
+ return cyc_to_sched_clock(&cd, cyc, (u32)~0);
+}
+
+static void notrace clksrc_dbx500_prcmu_update_sched_clock(void)
+{
+ u32 cyc = clksrc_dbx500_prcmu_read(&clocksource_dbx500_prcmu);
+ update_sched_clock(&cd, cyc, (u32)~0);
+}
+#endif
+
+void __init clksrc_dbx500_prcmu_init(void)
+{
+ /*
+ * 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(clksrc_dbx500_timer_base + PRCMU_TIMER_MODE) !=
+ TIMER_MODE_CONTINOUS) {
+ writel(TIMER_MODE_CONTINOUS,
+ clksrc_dbx500_timer_base + PRCMU_TIMER_MODE);
+ writel(TIMER_DOWNCOUNT_VAL,
+ clksrc_dbx500_timer_base + PRCMU_TIMER_REF);
+ }
+#ifdef CONFIG_CLKSRC_DBX500_PRCMU_SCHED_CLOCK
+ init_sched_clock(&cd, clksrc_dbx500_prcmu_update_sched_clock,
+ 32, RATE_32K);
+#endif
+ clocksource_calc_mult_shift(&clocksource_dbx500_prcmu,
+ RATE_32K, SCHED_CLOCK_MIN_WRAP);
+ clocksource_register(&clocksource_dbx500_prcmu);
+}