diff options
Diffstat (limited to 'drivers/cpufreq/ppc_cbe_cpufreq.c')
| -rw-r--r-- | drivers/cpufreq/ppc_cbe_cpufreq.c | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/drivers/cpufreq/ppc_cbe_cpufreq.c b/drivers/cpufreq/ppc_cbe_cpufreq.c new file mode 100644 index 000000000000..e577a1dbbfcd --- /dev/null +++ b/drivers/cpufreq/ppc_cbe_cpufreq.c @@ -0,0 +1,209 @@ +/* + * cpufreq driver for the cell processor + * + * (C) Copyright IBM Deutschland Entwicklung GmbH 2005-2007 + * + * Author: Christian Krafft <krafft@de.ibm.com> + * + * 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, 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, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <linux/cpufreq.h> +#include <linux/module.h> +#include <linux/of_platform.h> + +#include <asm/machdep.h> +#include <asm/prom.h> +#include <asm/cell-regs.h> + +#include "ppc_cbe_cpufreq.h" + +static DEFINE_MUTEX(cbe_switch_mutex); + + +/* the CBE supports an 8 step frequency scaling */ +static struct cpufreq_frequency_table cbe_freqs[] = { + {1, 0}, + {2, 0}, + {3, 0}, + {4, 0}, + {5, 0}, + {6, 0}, + {8, 0}, + {10, 0}, + {0, CPUFREQ_TABLE_END}, +}; + +/* + * hardware specific functions + */ + +static int set_pmode(unsigned int cpu, unsigned int slow_mode) +{ + int rc; + + if (cbe_cpufreq_has_pmi) + rc = cbe_cpufreq_set_pmode_pmi(cpu, slow_mode); + else + rc = cbe_cpufreq_set_pmode(cpu, slow_mode); + + pr_debug("register contains slow mode %d\n", cbe_cpufreq_get_pmode(cpu)); + + return rc; +} + +/* + * cpufreq functions + */ + +static int cbe_cpufreq_cpu_init(struct cpufreq_policy *policy) +{ + const u32 *max_freqp; + u32 max_freq; + int i, cur_pmode; + struct device_node *cpu; + + cpu = of_get_cpu_node(policy->cpu, NULL); + + if (!cpu) + return -ENODEV; + + pr_debug("init cpufreq on CPU %d\n", policy->cpu); + + /* + * Let's check we can actually get to the CELL regs + */ + if (!cbe_get_cpu_pmd_regs(policy->cpu) || + !cbe_get_cpu_mic_tm_regs(policy->cpu)) { + pr_info("invalid CBE regs pointers for cpufreq\n"); + return -EINVAL; + } + + max_freqp = of_get_property(cpu, "clock-frequency", NULL); + + of_node_put(cpu); + + if (!max_freqp) + return -EINVAL; + + /* we need the freq in kHz */ + max_freq = *max_freqp / 1000; + + pr_debug("max clock-frequency is at %u kHz\n", max_freq); + pr_debug("initializing frequency table\n"); + + /* initialize frequency table */ + for (i=0; cbe_freqs[i].frequency!=CPUFREQ_TABLE_END; i++) { + cbe_freqs[i].frequency = max_freq / cbe_freqs[i].index; + pr_debug("%d: %d\n", i, cbe_freqs[i].frequency); + } + + /* if DEBUG is enabled set_pmode() measures the latency + * of a transition */ + policy->cpuinfo.transition_latency = 25000; + + cur_pmode = cbe_cpufreq_get_pmode(policy->cpu); + pr_debug("current pmode is at %d\n",cur_pmode); + + policy->cur = cbe_freqs[cur_pmode].frequency; + +#ifdef CONFIG_SMP + cpumask_copy(policy->cpus, cpu_sibling_mask(policy->cpu)); +#endif + + cpufreq_frequency_table_get_attr(cbe_freqs, policy->cpu); + + /* this ensures that policy->cpuinfo_min + * and policy->cpuinfo_max are set correctly */ + return cpufreq_frequency_table_cpuinfo(policy, cbe_freqs); +} + +static int cbe_cpufreq_cpu_exit(struct cpufreq_policy *policy) +{ + cpufreq_frequency_table_put_attr(policy->cpu); + return 0; +} + +static int cbe_cpufreq_verify(struct cpufreq_policy *policy) +{ + return cpufreq_frequency_table_verify(policy, cbe_freqs); +} + +static int cbe_cpufreq_target(struct cpufreq_policy *policy, + unsigned int target_freq, + unsigned int relation) +{ + int rc; + struct cpufreq_freqs freqs; + unsigned int cbe_pmode_new; + + cpufreq_frequency_table_target(policy, + cbe_freqs, + target_freq, + relation, + &cbe_pmode_new); + + freqs.old = policy->cur; + freqs.new = cbe_freqs[cbe_pmode_new].frequency; + + mutex_lock(&cbe_switch_mutex); + cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE); + + pr_debug("setting frequency for cpu %d to %d kHz, " \ + "1/%d of max frequency\n", + policy->cpu, + cbe_freqs[cbe_pmode_new].frequency, + cbe_freqs[cbe_pmode_new].index); + + rc = set_pmode(policy->cpu, cbe_pmode_new); + + cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE); + mutex_unlock(&cbe_switch_mutex); + + return rc; +} + +static struct cpufreq_driver cbe_cpufreq_driver = { + .verify = cbe_cpufreq_verify, + .target = cbe_cpufreq_target, + .init = cbe_cpufreq_cpu_init, + .exit = cbe_cpufreq_cpu_exit, + .name = "cbe-cpufreq", + .owner = THIS_MODULE, + .flags = CPUFREQ_CONST_LOOPS, +}; + +/* + * module init and destoy + */ + +static int __init cbe_cpufreq_init(void) +{ + if (!machine_is(cell)) + return -ENODEV; + + return cpufreq_register_driver(&cbe_cpufreq_driver); +} + +static void __exit cbe_cpufreq_exit(void) +{ + cpufreq_unregister_driver(&cbe_cpufreq_driver); +} + +module_init(cbe_cpufreq_init); +module_exit(cbe_cpufreq_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>"); |