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Diffstat (limited to 'arch/arm/plat-omap/timer-32k-sync.c')
-rw-r--r--arch/arm/plat-omap/timer-32k-sync.c324
1 files changed, 324 insertions, 0 deletions
diff --git a/arch/arm/plat-omap/timer-32k-sync.c b/arch/arm/plat-omap/timer-32k-sync.c
new file mode 100644
index 000000000000..24a00d4cd928
--- /dev/null
+++ b/arch/arm/plat-omap/timer-32k-sync.c
@@ -0,0 +1,324 @@
+/*
+ * timer-32k-sync.c -- OMAP 32k Sync Timer Clocksource Driver
+ *
+ * Copyright (C) 2005-2010 Tony Lindgren <tony@atomide.com>
+ * Copyright (C) 2010 Nokia Corporation
+ * Copyright (C) 2010 Felipe Balbi <me@felipebalbi.com>
+ * Copyright (C) 2009 Texas Instruments
+ * 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 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/time.h>
+#include <linux/clocksource.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+
+struct omap_32k_sync_device {
+ struct timespec persistent_ts;
+ struct clocksource cs;
+ cycles_t cycles;
+ cycles_t last_cycles;
+
+ struct device *dev;
+ struct clk *ick;
+ void __iomem *base;
+
+ /*
+ * 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()).
+ */
+ u32 offset_32k __read_mostly;
+};
+
+#define to_omap_32k(cs) (container_of(cs, struct omap_32k_sync_device, cs))
+
+static struct omap_32k_sync_device *thecs;
+
+static inline u32 omap_32k_sync_readl(const void __iomem *base, unsigned offset)
+{
+ return __raw_readl(base + offset);
+}
+
+static cycle_t omap_32k_sync_32k_read(struct clocksource *cs)
+{
+ struct omap_32k_sync_device *omap = to_omap_32k(cs);
+
+ return omap_32k_sync_readl(omap->base, 0x10) - omap->offset_32k;
+}
+
+/*
+ * 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)
+{
+ struct omap_32k_sync_device *omap = thecs;
+
+ if (!omap)
+ return 0;
+
+ return clocksource_cyc2ns(omap->cs.read(&omap->cs),
+ omap->cs.mult, omap->cs.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.
+ */
+void read_persistent_clock(struct timespec *ts)
+{
+ struct omap_32k_sync_device *omap = thecs;
+ unsigned long long nsecs;
+ cycles_t delta;
+ struct timespec *tsp;
+
+ if (!omap) {
+ ts->tv_sec = 0;
+ ts->tv_nsec = 0;
+ return;
+ }
+
+ tsp = &omap->persistent_ts;
+
+ omap->last_cycles = omap->cycles;
+ omap->cycles = omap->cs.read(&omap->cs);
+ delta = omap->cycles - omap->last_cycles;
+
+ nsecs = clocksource_cyc2ns(delta,
+ omap->cs.mult, omap->cs.shift);
+
+ timespec_add_ns(tsp, nsecs);
+ *ts = *tsp;
+}
+
+/* ------------------------------------------------------------------------- */
+#define DEVNAME "timer32k"
+#include <linux/fs.h>
+#include <linux/timer-32k.h>
+
+static int omap_32k_ioctl(struct inode *inode, struct file *file,
+ unsigned int cmd, unsigned long arg)
+{
+ struct omap_32k_sync_device *omap = thecs;
+
+ if (!omap)
+ return -ENODEV;
+
+ switch (cmd) {
+ case OMAP_32K_READ: {
+ uint32_t *t = (uint32_t *)arg;
+ *t = omap_32k_sync_readl(omap->base, 0x10) - omap->offset_32k;
+ return 0;
+ }
+ case OMAP_32K_READRAW: {
+ uint32_t *t = (uint32_t *)arg;
+ *t = omap_32k_sync_readl(omap->base, 0x10);
+ return 0;
+ }
+ }
+
+ return -EINVAL;
+}
+
+static int __init omap_32k_sync_register_chrdev(void)
+{
+ int major;
+ static struct file_operations fops = {
+ .ioctl = omap_32k_ioctl
+ };
+ static struct class *cls;
+ struct device *dev;
+
+ major = register_chrdev(0, DEVNAME, &fops);
+
+ if (major <= 0) {
+ printk(KERN_ERR "timer-32k-sync: unable to get major number\n");
+ goto exit_disable;
+ }
+
+ cls = class_create(THIS_MODULE, DEVNAME);
+
+ if (IS_ERR(cls)) {
+ printk(KERN_ERR "timer-32k-sync: unable to create device class\n");
+ goto exit_unregister;
+ }
+
+ dev = device_create(cls, NULL, MKDEV(major, 0), NULL, DEVNAME);
+
+ if (IS_ERR(dev)) {
+ printk(KERN_ERR "timer-32k-sync: unable to create device\n");
+ goto exit_destroy_class;
+ }
+
+ return 0;
+
+exit_destroy_class:
+ class_destroy(cls);
+exit_unregister:
+ unregister_chrdev(major, DEVNAME);
+exit_disable:
+ return -EBUSY;
+}
+/* ------------------------------------------------------------------------- */
+
+static int __init omap_32k_sync_probe(struct platform_device *pdev)
+{
+ struct omap_32k_sync_device *omap;
+ struct resource *res;
+ struct clk *ick;
+
+ int ret;
+
+ void __iomem *base;
+
+ omap = kzalloc(sizeof(*omap), GFP_KERNEL);
+ if (!omap) {
+ dev_dbg(&pdev->dev, "unable to allocate memory\n");
+ ret = -ENOMEM;
+ goto err0;
+ }
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res) {
+ dev_dbg(&pdev->dev, "couldn't get resource\n");
+ ret = -ENODEV;
+ goto err1;
+ }
+
+ base = ioremap(res->start, resource_size(res));
+ if (!base) {
+ dev_dbg(&pdev->dev, "ioremap failed\n");
+ ret = -ENOMEM;
+ goto err2;
+ }
+
+ ick = clk_get(&pdev->dev, "ick");
+ if (IS_ERR(ick)) {
+ dev_dbg(&pdev->dev, "couldn't get clock\n");
+ ret = PTR_ERR(ick);
+ goto err3;
+ }
+
+ ret = clk_enable(ick);
+ if (ret) {
+ dev_dbg(&pdev->dev, "couldn't enable clock\n");
+ goto err4;
+ }
+
+ omap->base = base;
+ omap->dev = &pdev->dev;
+ omap->ick = ick;
+
+ omap->cs.name = "timer-32k";
+ omap->cs.rating = 250;
+ omap->cs.read = omap_32k_sync_32k_read;
+ omap->cs.mask = CLOCKSOURCE_MASK(32);
+ omap->cs.shift = 10;
+ omap->cs.flags = CLOCK_SOURCE_IS_CONTINUOUS;
+ omap->cs.mult = clocksource_hz2mult(32768, omap->cs.shift);
+
+ platform_set_drvdata(pdev, omap);
+
+ ret = clocksource_register(&omap->cs);
+ if (ret) {
+ dev_dbg(&pdev->dev, "failed to register clocksource\n");
+ goto err5;
+ }
+
+ /* initialize our offset */
+ omap->offset_32k = omap_32k_sync_32k_read(&omap->cs);
+
+ /*
+ * REVISIT for now we need to keep a global static pointer
+ * to this clocksource instance. Would it make any sense
+ * to provide a get_clocksource() to fetch the clocksource
+ * we just registered ?
+ */
+ thecs = omap;
+
+ omap_32k_sync_register_chrdev();
+
+ return 0;
+
+err5:
+ clk_disable(ick);
+
+err4:
+ clk_put(ick);
+
+err3:
+ iounmap(base);
+
+err2:
+err1:
+ kfree(omap);
+
+err0:
+ return ret;
+}
+
+static int __exit omap_32k_sync_remove(struct platform_device *pdev)
+{
+ struct omap_32k_sync_device *omap = platform_get_drvdata(pdev);
+
+ clocksource_unregister(&omap->cs);
+ clk_disable(omap->ick);
+ clk_put(omap->ick);
+ iounmap(omap->base);
+ kfree(omap);
+ platform_set_drvdata(pdev, NULL);
+
+ return 0;
+}
+
+static void omap_32k_sync_shutdown(struct platform_device *pdev)
+{
+ struct omap_32k_sync_device *omap = platform_get_drvdata(pdev);
+
+ clk_disable(omap->ick);
+}
+
+static struct platform_driver omap_32k_sync_driver = {
+ .remove = __exit_p(omap_32k_sync_remove),
+ .shutdown = omap_32k_sync_shutdown,
+ .driver = {
+ .name = "omap-32k-sync-timer",
+ },
+};
+
+static int __init omap_32k_sync_init(void)
+{
+ return platform_driver_probe(&omap_32k_sync_driver, omap_32k_sync_probe);
+}
+arch_initcall(omap_32k_sync_init);
+
+static void __exit omap_32k_sync_exit(void)
+{
+ platform_driver_unregister(&omap_32k_sync_driver);
+}
+module_exit(omap_32k_sync_exit);
+
+MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>");
+MODULE_LICENSE("GPL v2");
+
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-03 01:50:49 +0000