summaryrefslogtreecommitdiff
path: root/arch/arm/plat-omap/counter_32k.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/arm/plat-omap/counter_32k.c')
-rw-r--r--arch/arm/plat-omap/counter_32k.c183
1 files changed, 183 insertions, 0 deletions
diff --git a/arch/arm/plat-omap/counter_32k.c b/arch/arm/plat-omap/counter_32k.c
new file mode 100644
index 000000000000..155fe43a672b
--- /dev/null
+++ b/arch/arm/plat-omap/counter_32k.c
@@ -0,0 +1,183 @@
+/*
+ * OMAP 32ksynctimer/counter_32k-related code
+ *
+ * Copyright (C) 2009 Texas Instruments
+ * Copyright (C) 2010 Nokia Corporation
+ * Tony Lindgren <tony@atomide.com>
+ * Added OMAP4 support - Santosh Shilimkar <santosh.shilimkar@ti.com>
+ *
+ * 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.
+ *
+ * NOTE: This timer is not the same timer as the old OMAP1 MPU timer.
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+
+#include <plat/common.h>
+#include <plat/board.h>
+
+#include <plat/clock.h>
+
+
+/*
+ * 32KHz clocksource ... always available, on pretty most chips except
+ * OMAP 730 and 1510. Other timers could be used as clocksources, with
+ * higher resolution in free-running counter modes (e.g. 12 MHz xtal),
+ * but systems won't necessarily want to spend resources that way.
+ */
+
+#define OMAP16XX_TIMER_32K_SYNCHRONIZED 0xfffbc410
+
+#if !(defined(CONFIG_ARCH_OMAP730) || defined(CONFIG_ARCH_OMAP15XX))
+
+#include <linux/clocksource.h>
+
+/*
+ * offset_32k holds the init time counter value. It is then subtracted
+ * from every counter read to achieve a counter that counts time from the
+ * kernel boot (needed for sched_clock()).
+ */
+static u32 offset_32k __read_mostly;
+
+#ifdef CONFIG_ARCH_OMAP16XX
+static cycle_t omap16xx_32k_read(struct clocksource *cs)
+{
+ return omap_readl(OMAP16XX_TIMER_32K_SYNCHRONIZED) - offset_32k;
+}
+#else
+#define omap16xx_32k_read NULL
+#endif
+
+#ifdef CONFIG_ARCH_OMAP2420
+static cycle_t omap2420_32k_read(struct clocksource *cs)
+{
+ return omap_readl(OMAP2420_32KSYNCT_BASE + 0x10) - offset_32k;
+}
+#else
+#define omap2420_32k_read NULL
+#endif
+
+#ifdef CONFIG_ARCH_OMAP2430
+static cycle_t omap2430_32k_read(struct clocksource *cs)
+{
+ return omap_readl(OMAP2430_32KSYNCT_BASE + 0x10) - offset_32k;
+}
+#else
+#define omap2430_32k_read NULL
+#endif
+
+#ifdef CONFIG_ARCH_OMAP3
+static cycle_t omap34xx_32k_read(struct clocksource *cs)
+{
+ return omap_readl(OMAP3430_32KSYNCT_BASE + 0x10) - offset_32k;
+}
+#else
+#define omap34xx_32k_read NULL
+#endif
+
+#ifdef CONFIG_ARCH_OMAP4
+static cycle_t omap44xx_32k_read(struct clocksource *cs)
+{
+ return omap_readl(OMAP4430_32KSYNCT_BASE + 0x10) - offset_32k;
+}
+#else
+#define omap44xx_32k_read NULL
+#endif
+
+/*
+ * Kernel assumes that sched_clock can be called early but may not have
+ * things ready yet.
+ */
+static cycle_t omap_32k_read_dummy(struct clocksource *cs)
+{
+ return 0;
+}
+
+static struct clocksource clocksource_32k = {
+ .name = "32k_counter",
+ .rating = 250,
+ .read = omap_32k_read_dummy,
+ .mask = CLOCKSOURCE_MASK(32),
+ .shift = 10,
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+/*
+ * Returns current time from boot in nsecs. It's OK for this to wrap
+ * around for now, as it's just a relative time stamp.
+ */
+unsigned long long sched_clock(void)
+{
+ return clocksource_cyc2ns(clocksource_32k.read(&clocksource_32k),
+ clocksource_32k.mult, clocksource_32k.shift);
+}
+
+/**
+ * read_persistent_clock - Return time from a persistent clock.
+ *
+ * Reads the time from a source which isn't disabled during PM, the
+ * 32k sync timer. Convert the cycles elapsed since last read into
+ * nsecs and adds to a monotonically increasing timespec.
+ */
+static struct timespec persistent_ts;
+static cycles_t cycles, last_cycles;
+void read_persistent_clock(struct timespec *ts)
+{
+ unsigned long long nsecs;
+ cycles_t delta;
+ struct timespec *tsp = &persistent_ts;
+
+ last_cycles = cycles;
+ cycles = clocksource_32k.read(&clocksource_32k);
+ delta = cycles - last_cycles;
+
+ nsecs = clocksource_cyc2ns(delta,
+ clocksource_32k.mult, clocksource_32k.shift);
+
+ timespec_add_ns(tsp, nsecs);
+ *ts = *tsp;
+}
+
+static int __init omap_init_clocksource_32k(void)
+{
+ static char err[] __initdata = KERN_ERR
+ "%s: can't register clocksource!\n";
+
+ if (cpu_is_omap16xx() || cpu_class_is_omap2()) {
+ struct clk *sync_32k_ick;
+
+ if (cpu_is_omap16xx())
+ clocksource_32k.read = omap16xx_32k_read;
+ else if (cpu_is_omap2420())
+ clocksource_32k.read = omap2420_32k_read;
+ else if (cpu_is_omap2430())
+ clocksource_32k.read = omap2430_32k_read;
+ else if (cpu_is_omap34xx())
+ clocksource_32k.read = omap34xx_32k_read;
+ else if (cpu_is_omap44xx())
+ clocksource_32k.read = omap44xx_32k_read;
+ else
+ return -ENODEV;
+
+ sync_32k_ick = clk_get(NULL, "omap_32ksync_ick");
+ if (sync_32k_ick)
+ clk_enable(sync_32k_ick);
+
+ clocksource_32k.mult = clocksource_hz2mult(32768,
+ clocksource_32k.shift);
+
+ offset_32k = clocksource_32k.read(&clocksource_32k);
+
+ if (clocksource_register(&clocksource_32k))
+ printk(err, clocksource_32k.name);
+ }
+ return 0;
+}
+arch_initcall(omap_init_clocksource_32k);
+
+#endif /* !(defined(CONFIG_ARCH_OMAP730) || defined(CONFIG_ARCH_OMAP15XX)) */
+