ARM: omap: 32ktimer: Turn into a driver

Turn OMAP 32KHz timer into a driver and move to drivers/clocksource.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 106 insertions, 0 deletions

diff --git a/drivers/clocksource/timer-ti-32k.c b/drivers/clocksource/timer-ti-32k.c
new file mode 100644
index 0000000000..f93ab5bcff
--- /dev/null
+++ b/drivers/clocksource/timer-ti-32k.c
@@ -0,0 +1,106 @@
+/**
+ * @file
+ * @brief Provide @ref clocksource functionality for OMAP
+ *
+ * @ref clocksource provides a neat architecture. all we do is
+ * To loop in with Sync 32Khz clock ticking away at 32768hz on OMAP.
+ * Sync 32Khz clock is an always ON clock.
+ *
+ * (C) Copyright 2008
+ * Texas Instruments, <www.ti.com>
+ * Nishanth Menon <x0nishan@ti.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <common.h>
+#include <clock.h>
+#include <init.h>
+#include <io.h>
+#include <mach/omap3-silicon.h>
+#include <mach/omap4-silicon.h>
+#include <mach/clocks.h>
+#include <mach/timers.h>
+#include <mach/sys_info.h>
+#include <mach/syslib.h>
+
+/** Sync 32Khz Timer registers */
+#define S32K_CR			0x10
+#define S32K_FREQUENCY		32768
+
+static void __iomem *timerbase;
+
+/**
+ * @brief Provide a simple clock read
+ *
+ * Nothing is simpler.. read direct from clock and provide it
+ * to the caller.
+ *
+ * @return S32K clock counter
+ */
+static uint64_t s32k_clocksource_read(void)
+{
+	return readl(timerbase + S32K_CR);
+}
+
+/* A bit obvious isn't it? */
+static struct clocksource s32k_cs = {
+	.read = s32k_clocksource_read,
+	.mask	= CLOCKSOURCE_MASK(32),
+	.shift = 10,
+};
+
+/**
+ * @brief Initialize the Clock
+ *
+ * There is nothing to do on OMAP as SYNC32K clock is
+ * always on, and we do a simple data structure initialization.
+ * 32K clock gives 32768 ticks a seconds
+ *
+ * @return result of @ref init_clock
+ */
+static int omap_32ktimer_probe(struct device_d *dev)
+{
+	struct resource *iores;
+
+	/* one timer is enough */
+	if (timerbase)
+		return 0;
+
+	iores = dev_request_mem_resource(dev, 0);
+	if (IS_ERR(iores))
+		return PTR_ERR(iores);
+	timerbase = IOMEM(iores->start);
+
+	s32k_cs.mult = clocksource_hz2mult(S32K_FREQUENCY, s32k_cs.shift);
+
+	return init_clock(&s32k_cs);
+}
+
+static __maybe_unused struct of_device_id omap_32ktimer_dt_ids[] = {
+	{
+		.compatible = "ti,omap-counter32k",
+	}, {
+		/* sentinel */
+	}
+};
+
+static struct driver_d omap_32ktimer_driver = {
+	.name = "omap-32ktimer",
+	.probe = omap_32ktimer_probe,
+	.of_compatible = DRV_OF_COMPAT(omap_32ktimer_dt_ids),
+};
+
+static int omap_32ktimer_init(void)
+{
+	return platform_driver_register(&omap_32ktimer_driver);
+}
+postcore_initcall(omap_32ktimer_init);