Hi Richard, A couple of questions inline, but otherwise looks nice!
Jamie On Fri, Dec 16, 2011 at 06:30:59PM +0800, Richard Zhao wrote: > It support single core and multi-core ARM SoCs. But it assume > all cores share the same frequency and voltage. > > Signed-off-by: Richard Zhao <richard.z...@linaro.org> > --- [...] > diff --git a/drivers/cpufreq/arm-cpufreq.c b/drivers/cpufreq/arm-cpufreq.c > new file mode 100644 > index 0000000..e4d20da > --- /dev/null > +++ b/drivers/cpufreq/arm-cpufreq.c > @@ -0,0 +1,269 @@ > +/* > + * Copyright (C) 2011 Freescale Semiconductor, Inc. > + */ > + > +/* > + * The code contained herein is licensed under the GNU General Public > + * License. You may obtain a copy of the GNU General Public License > + * Version 2 or later at the following locations: > + * > + * http://www.opensource.org/licenses/gpl-license.html > + * http://www.gnu.org/copyleft/gpl.html > + */ > + > +#include <linux/module.h> > +#include <linux/cpufreq.h> > +#include <linux/clk.h> > +#include <linux/regulator/consumer.h> > +#include <linux/err.h> > +#include <linux/slab.h> > +#include <linux/of.h> > +#include <asm/cpu.h> > + > +static u32 *cpu_freqs; /* HZ */ > +static u32 *cpu_volts; /* uV */ > +static u32 trans_latency; /* ns */ > +static int cpu_op_nr; > + > +static DEFINE_PER_CPU(unsigned long, l_p_j_ref); > +static unsigned long l_p_j_ref_freq; > + > +static struct clk *cpu_clk; This assumes that all CPU's share the same clk and run at the same rate. Is that a fair/safe assumption? I honestly don't know the answer to this so it's just a question!!! > +static struct regulator *cpu_reg; > +static struct cpufreq_frequency_table *arm_freq_table; > + > +static int set_cpu_freq(unsigned long freq, int index, int higher) > +{ > + int ret = 0; > + > + if (higher && cpu_reg) > + regulator_set_voltage(cpu_reg, > + cpu_volts[index], cpu_volts[index]); > + > + ret = clk_set_rate(cpu_clk, freq); > + if (ret != 0) { > + printk(KERN_DEBUG "cannot set CPU clock rate\n"); Perhaps use pr_debug() and friends throughout this driver? > + return ret; > + } > + > + if (!higher && cpu_reg) > + regulator_set_voltage(cpu_reg, > + cpu_volts[index], cpu_volts[index]); > + > + return ret; > +} > + > +static int arm_verify_speed(struct cpufreq_policy *policy) > +{ > + return cpufreq_frequency_table_verify(policy, arm_freq_table); > +} > + > +static unsigned int arm_get_speed(unsigned int cpu) > +{ > + return clk_get_rate(cpu_clk) / 1000; > +} > + > +static int arm_set_target(struct cpufreq_policy *policy, > + unsigned int target_freq, unsigned int relation) > +{ > + struct cpufreq_freqs freqs; > + unsigned long freq_Hz; > + int cpu; > + int ret = 0; > + unsigned int index; > + > + cpufreq_frequency_table_target(policy, arm_freq_table, > + target_freq, relation, &index); > + freq_Hz = clk_round_rate(cpu_clk, cpu_freqs[index]); > + freq_Hz = freq_Hz ? freq_Hz : cpu_freqs[index]; > + freqs.old = clk_get_rate(cpu_clk) / 1000; > + freqs.new = clk_round_rate(cpu_clk, cpu_freqs[index]); > + freqs.new = freq_Hz / 1000; Why round the rate then overwrite it? Should this be freqs.new /= 1000? > + freqs.flags = 0; > + > + if (freqs.old == freqs.new) > + return 0; > + > + for_each_possible_cpu(cpu) { > + freqs.cpu = cpu; > + cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); > + } > + > + ret = set_cpu_freq(freq_Hz, index, (freqs.new > freqs.old)); > + > +#ifdef CONFIG_SMP > + /* loops_per_jiffy is not updated by the cpufreq core for SMP systems. > + * So update it for all CPUs. > + */ > + for_each_possible_cpu(cpu) > + per_cpu(cpu_data, cpu).loops_per_jiffy = > + cpufreq_scale(per_cpu(l_p_j_ref, cpu), l_p_j_ref_freq, > + freqs.new); > +#endif > + > + for_each_possible_cpu(cpu) { > + freqs.cpu = cpu; > + cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); > + } > + > + return ret; > +} > + > +static int arm_cpufreq_init(struct cpufreq_policy *policy) > +{ > + int ret; > + > + if (policy->cpu >= num_possible_cpus()) > + return -EINVAL; > + > + policy->cur = clk_get_rate(cpu_clk) / 1000; > + policy->shared_type = CPUFREQ_SHARED_TYPE_ANY; > + cpumask_setall(policy->cpus); > + /* Manual states, that PLL stabilizes in two CLK32 periods */ > + policy->cpuinfo.transition_latency = trans_latency; > + > + ret = cpufreq_frequency_table_cpuinfo(policy, arm_freq_table); > + > + if (ret < 0) { > + printk(KERN_ERR "%s: invalid frequency table for cpu %d\n", > + __func__, policy->cpu); > + return ret; > + } > + > + cpufreq_frequency_table_get_attr(arm_freq_table, policy->cpu); > + return 0; > +} > + > +static int arm_cpufreq_exit(struct cpufreq_policy *policy) > +{ > + cpufreq_frequency_table_put_attr(policy->cpu); > + return 0; > +} > + > +static struct cpufreq_driver arm_cpufreq_driver = { > + .flags = CPUFREQ_STICKY, > + .verify = arm_verify_speed, > + .target = arm_set_target, > + .get = arm_get_speed, > + .init = arm_cpufreq_init, > + .exit = arm_cpufreq_exit, > + .name = "arm", Is this really just for ARM or can it be a generic-clk driver? I can't see any ARM specifics here. > +}; > + > +static int __devinit arm_cpufreq_driver_init(void) > +{ > + struct device_node *cpu0; > + const struct property *pp; > + int cpu, i, ret; > + > + printk(KERN_INFO "ARM SoC generic CPU frequency driver\n"); > + > + cpu0 = of_find_node_by_path("/cpus/cpu@0"); > + if (!cpu0) > + return -ENODEV; > + > + pp = of_find_property(cpu0, "cpu-freqs", NULL); > + if (!pp) { > + ret = -ENODEV; > + goto put_node; > + } > + cpu_op_nr = pp->length / sizeof(u32); > + if (!cpu_op_nr) { > + ret = -ENODEV; > + goto put_node; > + } > + ret = -ENOMEM; > + cpu_freqs = kzalloc(sizeof(*cpu_freqs) * cpu_op_nr, GFP_KERNEL); > + if (!cpu_freqs) > + goto put_node; > + of_property_read_u32_array(cpu0, "cpu-freqs", cpu_freqs, cpu_op_nr); > + > + pp = of_find_property(cpu0, "cpu-volts", NULL); > + if (pp) { > + if (cpu_op_nr == pp->length / sizeof(u32)) { > + cpu_volts = kzalloc(sizeof(*cpu_freqs) * cpu_op_nr, > + GFP_KERNEL); > + if (!cpu_volts) > + goto free_cpu_freqs; > + of_property_read_u32_array(cpu0, "cpu-volts", > + cpu_volts, cpu_op_nr); > + } else > + printk(KERN_WARNING "cpufreq: invalid cpu_volts!\n"); > + } > + > + if (of_property_read_u32(cpu0, "trans-latency", &trans_latency)) > + trans_latency = CPUFREQ_ETERNAL; > + > + arm_freq_table = kmalloc(sizeof(struct cpufreq_frequency_table) > + * (cpu_op_nr + 1), GFP_KERNEL); > + if (!arm_freq_table) > + goto free_cpu_volts; > + > + for (i = 0; i < cpu_op_nr; i++) { > + arm_freq_table[i].index = i; > + arm_freq_table[i].frequency = cpu_freqs[i] / 1000; > + } > + > + arm_freq_table[i].index = i; > + arm_freq_table[i].frequency = CPUFREQ_TABLE_END; > + > + cpu_clk = clk_get(NULL, "cpu"); > + if (IS_ERR(cpu_clk)) { > + printk(KERN_ERR "%s: failed to get cpu clock\n", __func__); > + ret = PTR_ERR(cpu_clk); > + goto free_freq_table; > + } Should there be a clk_prepare() + clk_enable() pair here? I can't see it would really be needed but maybe for completeness? Again, just a question! > + > + if (cpu_volts) { > + cpu_reg = regulator_get(NULL, "cpu"); > + if (IS_ERR(cpu_reg)) { > + printk(KERN_WARNING > + "cpufreq: regulator cpu get failed.\n"); > + cpu_reg = NULL; > + } > + } > + > + l_p_j_ref_freq = clk_get_rate(cpu_clk); > + for_each_possible_cpu(cpu) > + per_cpu(l_p_j_ref, cpu) = > + per_cpu(cpu_data, cpu).loops_per_jiffy; > + > + ret = cpufreq_register_driver(&arm_cpufreq_driver); > + if (ret) > + goto reg_put; > + > + of_node_put(cpu0); > + > + return 0; > + > +reg_put: > + if (cpu_reg) > + regulator_put(cpu_reg); > + clk_put(cpu_clk); > +free_freq_table: > + kfree(arm_freq_table); > +free_cpu_volts: > + kfree(cpu_volts); > +free_cpu_freqs: > + kfree(cpu_freqs); > +put_node: > + of_node_put(cpu0); > + > + return ret; > +} > + > +static void arm_cpufreq_driver_exit(void) > +{ > + cpufreq_unregister_driver(&arm_cpufreq_driver); > + kfree(cpu_freqs); > + kfree(cpu_volts); > + kfree(arm_freq_table); > + clk_put(cpu_clk); > +} > + > +module_init(arm_cpufreq_driver_init); > +module_exit(arm_cpufreq_driver_exit); Are there any ARM platforms that wouldn't be able to use this driver? If there are then should platforms "opt-in" by calling a register function rather than having it auto registering as when we have multiple platforms in a single zImage the probe errors might not be too nice. > + > +MODULE_AUTHOR("Freescale Semiconductor Inc. Richard Zhao > <richard.z...@freescale.com>"); > +MODULE_DESCRIPTION("ARM SoC generic CPUFreq driver"); > +MODULE_LICENSE("GPL"); > -- > 1.7.5.4 > > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-ker...@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel _______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
