diff options
Diffstat (limited to 'arch/blackfin/mach-common/cpufreq.c')
| -rw-r--r-- | arch/blackfin/mach-common/cpufreq.c | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/arch/blackfin/mach-common/cpufreq.c b/arch/blackfin/mach-common/cpufreq.c new file mode 100644 index 00000000000..ed81e00d20e --- /dev/null +++ b/arch/blackfin/mach-common/cpufreq.c @@ -0,0 +1,194 @@ +/* + * 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); |