On Fri, Dec 16, 2011 at 10:52:29AM +0000, Jamie Iles wrote: > Hi Richard, > > A couple of questions inline, but otherwise looks nice! Thanks for your review. > > 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.zhao@xxxxxxxxxx> > > --- > [...] > > 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!!! As I know, most share the same clk/volt. From the code: IMX6: yes Tegra: Yes, but strange it sets CPUFREQ_SHARED_TYPE_ALL. MSM is an exception. I can support the case, but I have to make sure it's handy to use. > > > +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? ok. Thanks. > > > + 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]); I forgot to delete this line. > > + 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. If we make recalculating smp loops_per_jiffy portable, this driver will be portable too. > > > +}; > > + > > +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! The cpu clock should already be prepared/enabled. The same to the regulator. IMHO, cpufreq is not used to handle cpu clk/power gating. The gating should be handled by cpu hotplug, idle and suspend/resume. Please correct me if I'm wrong. > > > + > > + 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. Good point. But would it be better to check cpu node compatible property? Thanks Richard > > > + > > +MODULE_AUTHOR("Freescale Semiconductor Inc. Richard Zhao <richard.zhao@xxxxxxxxxxxxx>"); > > +MODULE_DESCRIPTION("ARM SoC generic CPUFreq driver"); > > +MODULE_LICENSE("GPL"); > > -- > > 1.7.5.4 > > > > > > > > _______________________________________________ > > linux-arm-kernel mailing list > > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
