#include <linux/irq.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
+#include <linux/cpufreq.h>
#include <asm/blackfin.h>
+#include <asm/time.h>
#ifdef CONFIG_CYCLES_CLOCKSOURCE
+/* Accelerators for sched_clock()
+ * convert from cycles(64bits) => nanoseconds (64bits)
+ * basic equation:
+ * ns = cycles / (freq / ns_per_sec)
+ * ns = cycles * (ns_per_sec / freq)
+ * ns = cycles * (10^9 / (cpu_khz * 10^3))
+ * ns = cycles * (10^6 / cpu_khz)
+ *
+ * Then we use scaling math (suggested by george@mvista.com) to get:
+ * ns = cycles * (10^6 * SC / cpu_khz) / SC
+ * ns = cycles * cyc2ns_scale / SC
+ *
+ * And since SC is a constant power of two, we can convert the div
+ * into a shift.
+ *
+ * We can use khz divisor instead of mhz to keep a better precision, since
+ * cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits.
+ * (mathieu.desnoyers@polymtl.ca)
+ *
+ * -johnstul@us.ibm.com "math is hard, lets go shopping!"
+ */
+
static unsigned long cyc2ns_scale;
#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
{
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC: {
- unsigned long tcount = ((get_cclk() / (HZ * 1)) - 1);
+ unsigned long tcount = ((get_cclk() / (HZ * TIME_SCALE)) - 1);
bfin_write_TCNTL(TMPWR);
+ bfin_write_TSCALE(TIME_SCALE - 1);
CSYNC();
bfin_write_TPERIOD(tcount);
bfin_write_TCOUNT(tcount);
break;
}
case CLOCK_EVT_MODE_ONESHOT:
+ bfin_write_TSCALE(0);
bfin_write_TCOUNT(0);
bfin_write_TCNTL(TMPWR | TMREN);
CSYNC();
/*
* the TSCALE prescaler counter.
*/
- bfin_write_TSCALE(0);
+ bfin_write_TSCALE(TIME_SCALE - 1);
bfin_write_TPERIOD(0);
bfin_write_TCOUNT(0);
* Created:
* Description: This file contains the bfin-specific time handling details.
* Most of the stuff is located in the machine specific files.
+ * FIXME: (This file is subject for removal)
*
* Modified:
- * Copyright 2004-2006 Analog Devices Inc.
+ * Copyright 2004-2008 Analog Devices Inc.
*
* Bugs: Enter bugs at http://blackfin.uclinux.org/
*
#include <linux/irq.h>
#include <asm/blackfin.h>
+#include <asm/time.h>
/* This is an NTP setting */
#define TICK_SIZE (tick_nsec / 1000)
.flags = IRQF_DISABLED
};
-/*
- * The way that the Blackfin core timer works is:
- * - CCLK is divided by a programmable 8-bit pre-scaler (TSCALE)
- * - Every time TSCALE ticks, a 32bit is counted down (TCOUNT)
- *
- * If you take the fastest clock (1ns, or 1GHz to make the math work easier)
- * 10ms is 10,000,000 clock ticks, which fits easy into a 32-bit counter
- * (32 bit counter is 4,294,967,296ns or 4.2 seconds) so, we don't need
- * to use TSCALE, and program it to zero (which is pass CCLK through).
- * If you feel like using it, try to keep HZ * TIMESCALE to some
- * value that divides easy (like power of 2).
- */
-
-#define TIME_SCALE 1
-
static void
time_sched_init(irq_handler_t timer_routine)
{
--- /dev/null
+/*
+ * File: arch/blackfin/mach-common/cpufreq.c
+ * Based on:
+ * Author:
+ *
+ * Created:
+ * Description: Blackfin core clock scaling
+ *
+ * Modified:
+ * Copyright 2004-2008 Analog Devices Inc.
+ *
+ * Bugs: Enter bugs at http://blackfin.uclinux.org/
+ *
+ * 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, see the file COPYING, or write
+ * to the Free Software Foundation, Inc.,
+ * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/cpufreq.h>
+#include <linux/fs.h>
+#include <asm/blackfin.h>
+#include <asm/time.h>
+
+
+/* this is the table of CCLK frequencies, in Hz */
+/* .index is the entry in the auxillary dpm_state_table[] */
+static struct cpufreq_frequency_table bfin_freq_table[] = {
+ {
+ .frequency = CPUFREQ_TABLE_END,
+ .index = 0,
+ },
+ {
+ .frequency = CPUFREQ_TABLE_END,
+ .index = 1,
+ },
+ {
+ .frequency = CPUFREQ_TABLE_END,
+ .index = 2,
+ },
+ {
+ .frequency = CPUFREQ_TABLE_END,
+ .index = 0,
+ },
+};
+
+static struct bfin_dpm_state {
+ unsigned int csel; /* system clock divider */
+ unsigned int tscale; /* change the divider on the core timer interrupt */
+} dpm_state_table[3];
+
+/**************************************************************************/
+
+static unsigned int bfin_getfreq(unsigned int cpu)
+{
+ /* The driver only support single cpu */
+ if (cpu != 0)
+ return -1;
+
+ return get_cclk();
+}
+
+
+static int bfin_target(struct cpufreq_policy *policy,
+ unsigned int target_freq, unsigned int relation)
+{
+ unsigned int index, plldiv, tscale;
+ unsigned long flags, cclk_hz;
+ struct cpufreq_freqs freqs;
+
+ if (cpufreq_frequency_table_target(policy, bfin_freq_table,
+ target_freq, relation, &index))
+ return -EINVAL;
+
+ cclk_hz = bfin_freq_table[index].frequency;
+
+ freqs.old = bfin_getfreq(0);
+ freqs.new = cclk_hz;
+ freqs.cpu = 0;
+
+ pr_debug("cpufreq: changing cclk to %lu; target = %u, oldfreq = %u\n",
+ cclk_hz, target_freq, freqs.old);
+
+ cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+ local_irq_save(flags);
+ plldiv = (bfin_read_PLL_DIV() & SSEL) | dpm_state_table[index].csel;
+ tscale = dpm_state_table[index].tscale;
+ bfin_write_PLL_DIV(plldiv);
+ /* we have to adjust the core timer, because it is using cclk */
+ bfin_write_TSCALE(tscale);
+ SSYNC();
+ local_irq_restore(flags);
+ cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+
+ return 0;
+}
+
+static int bfin_verify_speed(struct cpufreq_policy *policy)
+{
+ return cpufreq_frequency_table_verify(policy, bfin_freq_table);
+}
+
+static int __init __bfin_cpu_init(struct cpufreq_policy *policy)
+{
+
+ unsigned long cclk, sclk, csel, min_cclk;
+ int index;
+
+#ifdef CONFIG_CYCLES_CLOCKSOURCE
+/*
+ * Clocksource CYCLES is still CONTINUOUS but not longer MONOTONIC in case we enable
+ * CPU frequency scaling, since CYCLES runs off Core Clock.
+ */
+ printk(KERN_WARNING "CPU frequency scaling not supported: Clocksource not suitable\n"
+ return -ENODEV;
+#endif
+
+ if (policy->cpu != 0)
+ return -EINVAL;
+
+ cclk = get_cclk();
+ sclk = get_sclk();
+
+#if ANOMALY_05000273
+ min_cclk = sclk * 2;
+#else
+ min_cclk = sclk;
+#endif
+ csel = ((bfin_read_PLL_DIV() & CSEL) >> 4);
+
+ for (index = 0; (cclk >> index) >= min_cclk && csel <= 3; index++, csel++) {
+ bfin_freq_table[index].frequency = cclk >> index;
+ dpm_state_table[index].csel = csel << 4; /* Shift now into PLL_DIV bitpos */
+ dpm_state_table[index].tscale = (TIME_SCALE / (1 << csel)) - 1;
+
+ pr_debug("cpufreq: freq:%d csel:%d tscale:%d\n",
+ bfin_freq_table[index].frequency,
+ dpm_state_table[index].csel,
+ dpm_state_table[index].tscale);
+ }
+
+ policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
+
+ policy->cpuinfo.transition_latency = (bfin_read_PLL_LOCKCNT() / (sclk / 1000000)) * 1000;
+ /*Now ,only support one cpu */
+ policy->cur = cclk;
+ cpufreq_frequency_table_get_attr(bfin_freq_table, policy->cpu);
+ return cpufreq_frequency_table_cpuinfo(policy, bfin_freq_table);
+}
+
+static struct freq_attr *bfin_freq_attr[] = {
+ &cpufreq_freq_attr_scaling_available_freqs,
+ NULL,
+};
+
+static struct cpufreq_driver bfin_driver = {
+ .verify = bfin_verify_speed,
+ .target = bfin_target,
+ .get = bfin_getfreq,
+ .init = __bfin_cpu_init,
+ .name = "bfin cpufreq",
+ .owner = THIS_MODULE,
+ .attr = bfin_freq_attr,
+};
+
+static int __init bfin_cpu_init(void)
+{
+ return cpufreq_register_driver(&bfin_driver);
+}
+
+static void __exit bfin_cpu_exit(void)
+{
+ cpufreq_unregister_driver(&bfin_driver);
+}
+
+MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
+MODULE_DESCRIPTION("cpufreq driver for Blackfin");
+MODULE_LICENSE("GPL");
+
+module_init(bfin_cpu_init);
+module_exit(bfin_cpu_exit);
--- /dev/null
+/*
+ * asm-blackfin/time.h:
+ *
+ * Copyright 2004-2008 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#ifndef _ASM_BLACKFIN_TIME_H
+#define _ASM_BLACKFIN_TIME_H
+
+/*
+ * The way that the Blackfin core timer works is:
+ * - CCLK is divided by a programmable 8-bit pre-scaler (TSCALE)
+ * - Every time TSCALE ticks, a 32bit is counted down (TCOUNT)
+ *
+ * If you take the fastest clock (1ns, or 1GHz to make the math work easier)
+ * 10ms is 10,000,000 clock ticks, which fits easy into a 32-bit counter
+ * (32 bit counter is 4,294,967,296ns or 4.2 seconds) so, we don't need
+ * to use TSCALE, and program it to zero (which is pass CCLK through).
+ * If you feel like using it, try to keep HZ * TIMESCALE to some
+ * value that divides easy (like power of 2).
+ */
+
+#ifndef CONFIG_CPU_FREQ
+#define TIME_SCALE 1
+#else
+/*
+ * Blackfin CPU frequency scaling supports max Core Clock 1, 1/2 and 1/4 .
+ * Whenever we change the Core Clock frequency changes we immediately
+ * adjust the Core Timer Presale Register. This way we don't lose time.
+ */
+#define TIME_SCALE 4
+#endif
+
+#endif
projects / linux-2.6 / commitdiff