summaryrefslogtreecommitdiffstats
path: root/arch/mips/mips-boards/generic/time.c
blob: 659706705005de54b94527910cc4a87e9e68e509 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
/*
 * Carsten Langgaard, carstenl@mips.com
 * Copyright (C) 1999,2000 MIPS Technologies, Inc.  All rights reserved.
 *
 *  This program is free software; you can distribute it and/or modify it
 *  under the terms of the GNU General Public License (Version 2) as
 *  published by the Free Software Foundation.
 *
 *  This program is distributed in the hope 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.
 *
 * Setting up the clock on the MIPS boards.
 */

#include <linux/types.h>
#include <linux/init.h>
#include <linux/kernel_stat.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/timex.h>
#include <linux/mc146818rtc.h>

#include <asm/mipsregs.h>
#include <asm/mipsmtregs.h>
#include <asm/hardirq.h>
#include <asm/irq.h>
#include <asm/div64.h>
#include <asm/cpu.h>
#include <asm/time.h>
#include <asm/mc146818-time.h>
#include <asm/msc01_ic.h>

#include <asm/mips-boards/generic.h>
#include <asm/mips-boards/prom.h>

#ifdef CONFIG_MIPS_ATLAS
#include <asm/mips-boards/atlasint.h>
#endif
#ifdef CONFIG_MIPS_MALTA
#include <asm/mips-boards/maltaint.h>
#endif

unsigned long cpu_khz;

#if defined(CONFIG_MIPS_ATLAS)
static char display_string[] = "        LINUX ON ATLAS       ";
#endif
#if defined(CONFIG_MIPS_MALTA)
#if defined(CONFIG_MIPS_MT_SMTC)
static char display_string[] = "       SMTC LINUX ON MALTA       ";
#else
static char display_string[] = "        LINUX ON MALTA       ";
#endif /* CONFIG_MIPS_MT_SMTC */
#endif
#if defined(CONFIG_MIPS_SEAD)
static char display_string[] = "        LINUX ON SEAD       ";
#endif
static unsigned int display_count;
#define MAX_DISPLAY_COUNT (sizeof(display_string) - 8)

#define CPUCTR_IMASKBIT (0x100 << MIPSCPU_INT_CPUCTR)

static unsigned int timer_tick_count;
static int mips_cpu_timer_irq;
extern void smtc_timer_broadcast(int);

static inline void scroll_display_message(void)
{
	if ((timer_tick_count++ % HZ) == 0) {
		mips_display_message(&display_string[display_count++]);
		if (display_count == MAX_DISPLAY_COUNT)
			display_count = 0;
	}
}

static void mips_timer_dispatch(void)
{
	do_IRQ(mips_cpu_timer_irq);
}

/*
 * Redeclare until I get around mopping the timer code insanity on MIPS.
 */
extern int null_perf_irq(void);

extern int (*perf_irq)(void);

irqreturn_t mips_timer_interrupt(int irq, void *dev_id)
{
	int cpu = smp_processor_id();

#ifdef CONFIG_MIPS_MT_SMTC
	/*
	 *  In an SMTC system, one Count/Compare set exists per VPE.
	 *  Which TC within a VPE gets the interrupt is essentially
	 *  random - we only know that it shouldn't be one with
	 *  IXMT set. Whichever TC gets the interrupt needs to
	 *  send special interprocessor interrupts to the other
	 *  TCs to make sure that they schedule, etc.
	 *
	 *  That code is specific to the SMTC kernel, not to
	 *  the a particular platform, so it's invoked from
	 *  the general MIPS timer_interrupt routine.
	 */

	int vpflags;

	/*
	 * We could be here due to timer interrupt,
	 * perf counter overflow, or both.
	 */
	if (read_c0_cause() & (1 << 26))
		perf_irq();

	if (read_c0_cause() & (1 << 30)) {
		/* If timer interrupt, make it de-assert */
		write_c0_compare (read_c0_count() - 1);
		/*
		 * DVPE is necessary so long as cross-VPE interrupts
		 * are done via read-modify-write of Cause register.
		 */
		vpflags = dvpe();
		clear_c0_cause(CPUCTR_IMASKBIT);
		evpe(vpflags);
		/*
		 * There are things we only want to do once per tick
		 * in an "MP" system.   One TC of each VPE will take
		 * the actual timer interrupt.  The others will get
		 * timer broadcast IPIs. We use whoever it is that takes
		 * the tick on VPE 0 to run the full timer_interrupt().
		 */
		if (cpu_data[cpu].vpe_id == 0) {
				timer_interrupt(irq, NULL);
				smtc_timer_broadcast(cpu_data[cpu].vpe_id);
				scroll_display_message();
		} else {
			write_c0_compare(read_c0_count() +
			                 (mips_hpt_frequency/HZ));
			local_timer_interrupt(irq, dev_id);
			smtc_timer_broadcast(cpu_data[cpu].vpe_id);
		}
	}
#else /* CONFIG_MIPS_MT_SMTC */
	int r2 = cpu_has_mips_r2;

	if (cpu == 0) {
		/*
		 * CPU 0 handles the global timer interrupt job and process
		 * accounting resets count/compare registers to trigger next
		 * timer int.
		 */
		if (!r2 || (read_c0_cause() & (1 << 26)))
			if (perf_irq())
				goto out;

		/* we keep interrupt disabled all the time */
		if (!r2 || (read_c0_cause() & (1 << 30)))
			timer_interrupt(irq, NULL);

		scroll_display_message();
	} else {
		/* Everyone else needs to reset the timer int here as
		   ll_local_timer_interrupt doesn't */
		/*
		 * FIXME: need to cope with counter underflow.
		 * More support needs to be added to kernel/time for
		 * counter/timer interrupts on multiple CPU's
		 */
		write_c0_compare(read_c0_count() + (mips_hpt_frequency/HZ));

		/*
		 * Other CPUs should do profiling and process accounting
		 */
		local_timer_interrupt(irq, dev_id);
	}
out:
#endif /* CONFIG_MIPS_MT_SMTC */
	return IRQ_HANDLED;
}

/*
 * Estimate CPU frequency.  Sets mips_hpt_frequency as a side-effect
 */
static unsigned int __init estimate_cpu_frequency(void)
{
	unsigned int prid = read_c0_prid() & 0xffff00;
	unsigned int count;

#if defined(CONFIG_MIPS_SEAD) || defined(CONFIG_MIPS_SIM)
	/*
	 * The SEAD board doesn't have a real time clock, so we can't
	 * really calculate the timer frequency
	 * For now we hardwire the SEAD board frequency to 12MHz.
	 */

	if ((prid == (PRID_COMP_MIPS | PRID_IMP_20KC)) ||
	    (prid == (PRID_COMP_MIPS | PRID_IMP_25KF)))
		count = 12000000;
	else
		count = 6000000;
#endif
#if defined(CONFIG_MIPS_ATLAS) || defined(CONFIG_MIPS_MALTA)
	unsigned long flags;

	local_irq_save(flags);

	/* Start counter exactly on falling edge of update flag */
	while (CMOS_READ(RTC_REG_A) & RTC_UIP);
	while (!(CMOS_READ(RTC_REG_A) & RTC_UIP));

	/* Start r4k counter. */
	write_c0_count(0);

	/* Read counter exactly on falling edge of update flag */
	while (CMOS_READ(RTC_REG_A) & RTC_UIP);
	while (!(CMOS_READ(RTC_REG_A) & RTC_UIP));

	count = read_c0_count();

	/* restore interrupts */
	local_irq_restore(flags);
#endif

	mips_hpt_frequency = count;
	if ((prid != (PRID_COMP_MIPS | PRID_IMP_20KC)) &&
	    (prid != (PRID_COMP_MIPS | PRID_IMP_25KF)))
		count *= 2;

	count += 5000;    /* round */
	count -= count%10000;

	return count;
}

unsigned long __init mips_rtc_get_time(void)
{
	return mc146818_get_cmos_time();
}

void __init mips_time_init(void)
{
	unsigned int est_freq;

        /* Set Data mode - binary. */
        CMOS_WRITE(CMOS_READ(RTC_CONTROL) | RTC_DM_BINARY, RTC_CONTROL);

	est_freq = estimate_cpu_frequency ();

	printk("CPU frequency %d.%02d MHz\n", est_freq/1000000,
	       (est_freq%1000000)*100/1000000);

        cpu_khz = est_freq / 1000;
}

void __init plat_timer_setup(struct irqaction *irq)
{
	if (cpu_has_veic) {
		set_vi_handler (MSC01E_INT_CPUCTR, mips_timer_dispatch);
		mips_cpu_timer_irq = MSC01E_INT_BASE + MSC01E_INT_CPUCTR;
	}
	else {
		if (cpu_has_vint)
			set_vi_handler (MIPSCPU_INT_CPUCTR, mips_timer_dispatch);
		mips_cpu_timer_irq = MIPSCPU_INT_BASE + MIPSCPU_INT_CPUCTR;
	}


	/* we are using the cpu counter for timer interrupts */
	irq->handler = mips_timer_interrupt;	/* we use our own handler */
#ifdef CONFIG_MIPS_MT_SMTC
	setup_irq_smtc(mips_cpu_timer_irq, irq, CPUCTR_IMASKBIT);
#else
	setup_irq(mips_cpu_timer_irq, irq);
#endif /* CONFIG_MIPS_MT_SMTC */

#ifdef CONFIG_SMP
	/* irq_desc(riptor) is a global resource, when the interrupt overlaps
	   on seperate cpu's the first one tries to handle the second interrupt.
	   The effect is that the int remains disabled on the second cpu.
	   Mark the interrupt with IRQ_PER_CPU to avoid any confusion */
	irq_desc[mips_cpu_timer_irq].status |= IRQ_PER_CPU;
#endif

        /* to generate the first timer interrupt */
	write_c0_compare (read_c0_count() + mips_hpt_frequency/HZ);
}