2 * OMAP 32ksynctimer/counter_32k-related code
4 * Copyright (C) 2009 Texas Instruments
5 * Copyright (C) 2010 Nokia Corporation
6 * Tony Lindgren <tony@atomide.com>
7 * Added OMAP4 support - Santosh Shilimkar <santosh.shilimkar@ti.com>
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
13 * NOTE: This timer is not the same timer as the old OMAP1 MPU timer.
15 #include <linux/kernel.h>
16 #include <linux/init.h>
17 #include <linux/clk.h>
18 #include <linux/err.h>
20 #include <linux/clocksource.h>
22 #include <asm/sched_clock.h>
24 #include <plat/hardware.h>
25 #include <plat/common.h>
26 #include <plat/board.h>
28 #include <plat/clock.h>
31 * 32KHz clocksource ... always available, on pretty most chips except
32 * OMAP 730 and 1510. Other timers could be used as clocksources, with
33 * higher resolution in free-running counter modes (e.g. 12 MHz xtal),
34 * but systems won't necessarily want to spend resources that way.
36 static void __iomem *timer_32k_base;
38 #define OMAP16XX_TIMER_32K_SYNCHRONIZED 0xfffbc410
40 static u32 notrace omap_32k_read_sched_clock(void)
42 return timer_32k_base ? __raw_readl(timer_32k_base) : 0;
46 * read_persistent_clock - Return time from a persistent clock.
48 * Reads the time from a source which isn't disabled during PM, the
49 * 32k sync timer. Convert the cycles elapsed since last read into
50 * nsecs and adds to a monotonically increasing timespec.
52 static struct timespec persistent_ts;
53 static cycles_t cycles, last_cycles;
54 static unsigned int persistent_mult, persistent_shift;
55 void read_persistent_clock(struct timespec *ts)
57 unsigned long long nsecs;
59 struct timespec *tsp = &persistent_ts;
62 cycles = timer_32k_base ? __raw_readl(timer_32k_base) : 0;
63 delta = cycles - last_cycles;
65 nsecs = clocksource_cyc2ns(delta, persistent_mult, persistent_shift);
67 timespec_add_ns(tsp, nsecs);
71 int __init omap_init_clocksource_32k(void)
73 static char err[] __initdata = KERN_ERR
74 "%s: can't register clocksource!\n";
76 if (cpu_is_omap16xx() || cpu_class_is_omap2()) {
78 unsigned long size = SZ_4K;
80 struct clk *sync_32k_ick;
82 if (cpu_is_omap16xx()) {
83 pbase = OMAP16XX_TIMER_32K_SYNCHRONIZED;
85 } else if (cpu_is_omap2420())
86 pbase = OMAP2420_32KSYNCT_BASE + 0x10;
87 else if (cpu_is_omap2430())
88 pbase = OMAP2430_32KSYNCT_BASE + 0x10;
89 else if (cpu_is_omap34xx())
90 pbase = OMAP3430_32KSYNCT_BASE + 0x10;
91 else if (cpu_is_omap44xx())
92 pbase = OMAP4430_32KSYNCT_BASE + 0x10;
96 /* For this to work we must have a static mapping in io.c for this area */
97 base = ioremap(pbase, size);
101 sync_32k_ick = clk_get(NULL, "omap_32ksync_ick");
102 if (!IS_ERR(sync_32k_ick))
103 clk_enable(sync_32k_ick);
105 timer_32k_base = base;
108 * 120000 rough estimate from the calculations in
109 * __clocksource_updatefreq_scale.
111 clocks_calc_mult_shift(&persistent_mult, &persistent_shift,
112 32768, NSEC_PER_SEC, 120000);
114 if (clocksource_mmio_init(base, "32k_counter", 32768, 250, 32,
115 clocksource_mmio_readl_up))
116 printk(err, "32k_counter");
118 setup_sched_clock(omap_32k_read_sched_clock, 32, 32768);