1 /*
2 * OMAP 32ksynctimer/counter_32k-related code
3 *
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>
8 *
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.
12 *
13 * NOTE: This timer is not the same timer as the old OMAP1 MPU timer.
14 */
15 #include <linux/kernel.h>
16 #include <linux/init.h>
17 #include <linux/clk.h>
18 #include <linux/err.h>
19 #include <linux/io.h>
20 #include <linux/clocksource.h>
21
22 #include <asm/sched_clock.h>
23
24 #include <plat/common.h>
25 #include <plat/board.h>
26
27 #include <plat/clock.h>
28
29 /*
30 * 32KHz clocksource ... always available, on pretty most chips except
31 * OMAP 730 and 1510. Other timers could be used as clocksources, with
32 * higher resolution in free-running counter modes (e.g. 12 MHz xtal),
33 * but systems won't necessarily want to spend resources that way.
34 */
35 static void __iomem *timer_32k_base;
36
37 #define OMAP16XX_TIMER_32K_SYNCHRONIZED 0xfffbc410
38
omap_32k_read_sched_clock(void)39 static u32 notrace omap_32k_read_sched_clock(void)
40 {
41 return timer_32k_base ? __raw_readl(timer_32k_base) : 0;
42 }
43
44 /**
45 * read_persistent_clock - Return time from a persistent clock.
46 *
47 * Reads the time from a source which isn't disabled during PM, the
48 * 32k sync timer. Convert the cycles elapsed since last read into
49 * nsecs and adds to a monotonically increasing timespec.
50 */
51 static struct timespec persistent_ts;
52 static cycles_t cycles, last_cycles;
53 static unsigned int persistent_mult, persistent_shift;
read_persistent_clock(struct timespec * ts)54 void read_persistent_clock(struct timespec *ts)
55 {
56 unsigned long long nsecs;
57 cycles_t delta;
58 struct timespec *tsp = &persistent_ts;
59
60 last_cycles = cycles;
61 cycles = timer_32k_base ? __raw_readl(timer_32k_base) : 0;
62 delta = cycles - last_cycles;
63
64 nsecs = clocksource_cyc2ns(delta, persistent_mult, persistent_shift);
65
66 timespec_add_ns(tsp, nsecs);
67 *ts = *tsp;
68 }
69
omap_init_clocksource_32k(void)70 int __init omap_init_clocksource_32k(void)
71 {
72 static char err[] __initdata = KERN_ERR
73 "%s: can't register clocksource!\n";
74
75 if (cpu_is_omap16xx() || cpu_class_is_omap2()) {
76 u32 pbase;
77 unsigned long size = SZ_4K;
78 void __iomem *base;
79 struct clk *sync_32k_ick;
80
81 if (cpu_is_omap16xx()) {
82 pbase = OMAP16XX_TIMER_32K_SYNCHRONIZED;
83 size = SZ_1K;
84 } else if (cpu_is_omap2420())
85 pbase = OMAP2420_32KSYNCT_BASE + 0x10;
86 else if (cpu_is_omap2430())
87 pbase = OMAP2430_32KSYNCT_BASE + 0x10;
88 else if (cpu_is_omap34xx())
89 pbase = OMAP3430_32KSYNCT_BASE + 0x10;
90 else if (cpu_is_omap44xx())
91 pbase = OMAP4430_32KSYNCT_BASE + 0x10;
92 else
93 return -ENODEV;
94
95 /* For this to work we must have a static mapping in io.c for this area */
96 base = ioremap(pbase, size);
97 if (!base)
98 return -ENODEV;
99
100 sync_32k_ick = clk_get(NULL, "omap_32ksync_ick");
101 if (!IS_ERR(sync_32k_ick))
102 clk_enable(sync_32k_ick);
103
104 timer_32k_base = base;
105
106 /*
107 * 120000 rough estimate from the calculations in
108 * __clocksource_updatefreq_scale.
109 */
110 clocks_calc_mult_shift(&persistent_mult, &persistent_shift,
111 32768, NSEC_PER_SEC, 120000);
112
113 if (clocksource_mmio_init(base, "32k_counter", 32768, 250, 32,
114 clocksource_mmio_readl_up))
115 printk(err, "32k_counter");
116
117 setup_sched_clock(omap_32k_read_sched_clock, 32, 32768);
118 }
119 return 0;
120 }
121