Re: [PATCHv3 6/6] drivers/cpufreq: Add a CPUFreq driver for AMD processors (Fam17h and later)

[Viresh Kumar]

On 10-07-19, 18:37, Natarajan, Janakarajan wrote:
> diff --git a/drivers/cpufreq/amd-cpufreq.c b/drivers/cpufreq/amd-cpufreq.c
> +#define pr_fmt(fmt)	"AMD Cpufreq: " fmt
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/cpu.h>
> +#include <linux/vmalloc.h>
> +#include <linux/cpufreq.h>
> +#include <linux/acpi.h>
> +#include <linux/delay.h>

Please keep them in alphabetical order.

> +
> +#include <asm/unaligned.h>
> +
> +#include <acpi/cppc_acpi.h>
> +
> +struct amd_desc {
> +	int cpu_id;
> +	struct cppc_ctrls ctrls;
> +	struct kobject kobj;
> +};
> +
> +struct amd_desc **all_cpu_data;
> +
> +static unsigned int cppc_enable;
> +module_param(cppc_enable, uint, 0644);
> +MODULE_PARM_DESC(cppc_enable,
> +		 "1 - enable AMD CpuFreq, create CPPC sysfs entries.");
> +
> +#define to_amd_desc(a) container_of(a, struct amd_desc, kobj)
> +
> +#define show_func(access_fn, struct_name, member_name)			\
> +	static ssize_t show_##member_name(struct kobject *kobj,		\
> +					  struct kobj_attribute *attr,	\
> +					  char *buf)			\
> +	{								\
> +		struct amd_desc *desc = to_amd_desc(kobj);		\
> +		struct struct_name st_name = {0};			\
> +		int ret;						\
> +									\
> +		ret = access_fn(desc->cpu_id, &st_name);		\
> +		if (ret)						\
> +			return ret;					\
> +									\
> +		return scnprintf(buf, PAGE_SIZE, "%llu\n",		\
> +				 (u64)st_name.member_name);		\
> +	}								\
> +
> +#define store_func(struct_name, member_name, reg_idx)			\
> +	static ssize_t store_##member_name(struct kobject *kobj,	\
> +					   struct kobj_attribute *attr,	\
> +					   const char *buf, size_t count)\
> +	{								\
> +		struct amd_desc *desc = to_amd_desc(kobj);		\
> +		struct struct_name st_name = {0};			\
> +		u32 val;						\
> +		int ret;						\
> +									\
> +		ret = kstrtou32(buf, 0, &val);				\
> +		if (ret)						\
> +			return ret;					\
> +									\
> +		st_name.member_name = val;				\
> +									\
> +		ret = cppc_set_reg(desc->cpu_id, &st_name, reg_idx);	\
> +		if (ret)						\
> +			return ret;					\
> +									\
> +		return count;						\
> +	}								\
> +
> +#define define_one_rw(struct_name, access_fn, member_name, reg_idx)	\
> +	show_func(access_fn, struct_name, member_name)			\
> +	store_func(struct_name, member_name, reg_idx)			\
> +	define_one_global_rw(member_name)
> +
> +define_one_rw(cppc_ctrls, cppc_get_ctrls, enable, ENABLE);
> +define_one_rw(cppc_ctrls, cppc_get_ctrls, max_perf, MAX_PERF);
> +define_one_rw(cppc_ctrls, cppc_get_ctrls, min_perf, MIN_PERF);
> +define_one_rw(cppc_ctrls, cppc_get_ctrls, desired_perf, DESIRED_PERF);
> +define_one_rw(cppc_ctrls, cppc_get_ctrls, auto_sel_enable, AUTO_SEL_ENABLE);
> +
> +static struct attribute *amd_cpufreq_attributes[] = {
> +	&enable.attr,
> +	&max_perf.attr,
> +	&min_perf.attr,
> +	&desired_perf.attr,
> +	&auto_sel_enable.attr,
> +	NULL
> +};
> +
> +static const struct attribute_group amd_cpufreq_attr_group = {
> +	.attrs = amd_cpufreq_attributes,
> +};
> +
> +static struct kobj_type amd_cpufreq_type = {
> +	.sysfs_ops = &kobj_sysfs_ops,
> +	.default_attrs = amd_cpufreq_attributes,
> +};
> +
> +static int amd_cpufreq_cpu_init(struct cpufreq_policy *policy)
> +{
> +	return 0;
> +}
> +
> +static int amd_cpufreq_cpu_exit(struct cpufreq_policy *policy)
> +{
> +	return 0;
> +}
> +
> +static int amd_cpufreq_cpu_verify(struct cpufreq_policy *policy)
> +{
> +	return 0;
> +}
> +
> +static int amd_cpufreq_cpu_target_index(struct cpufreq_policy *policy,
> +					unsigned int index)
> +{
> +	return 0;
> +}

All empty helpers ? There is nothing you need to do ?

> +
> +static struct cpufreq_driver amd_cpufreq_driver = {
> +	.name = "amd_cpufreq",
> +	.init = amd_cpufreq_cpu_init,
> +	.exit = amd_cpufreq_cpu_exit,
> +	.verify = amd_cpufreq_cpu_verify,
> +	.target_index = amd_cpufreq_cpu_target_index,
> +};
> +
> +static void amd_cpufreq_sysfs_delete_params(void)
> +{
> +	int i;
> +
> +	for_each_possible_cpu(i) {
> +		if (all_cpu_data[i]) {
> +			kobject_del(&all_cpu_data[i]->kobj);

Shouldn't you use kobject_put() instead of this ?

> +			kfree(all_cpu_data[i]);
> +		}
> +	}
> +
> +	kfree(all_cpu_data);
> +}
> +
> +static int __init amd_cpufreq_sysfs_expose_params(void)
> +{
> +	struct device *cpu_dev;
> +	int i, ret;
> +
> +	all_cpu_data = kcalloc(num_possible_cpus(), sizeof(void *),
> +			       GFP_KERNEL);
> +
> +	if (!all_cpu_data)
> +		return -ENOMEM;
> +
> +	for_each_possible_cpu(i) {
> +		all_cpu_data[i] = kzalloc(sizeof(struct amd_desc), GFP_KERNEL);
> +		if (!all_cpu_data[i]) {
> +			ret = -ENOMEM;
> +			goto free;
> +		}
> +
> +		all_cpu_data[i]->cpu_id = i;
> +		cpu_dev = get_cpu_device(i);
> +		ret = kobject_init_and_add(&all_cpu_data[i]->kobj, &amd_cpufreq_type,
> +					   &cpu_dev->kobj, "amd_cpufreq");
> +		if (ret)
> +			goto free;
> +	}
> +
> +	return 0;
> +free:
> +	amd_cpufreq_sysfs_delete_params();
> +	return ret;
> +}

Instead of doing this once for all CPUs, it would be better to do it
every time the ->init() callback of the driver gets called. If you
have one cpufreq policy for each CPU (i.e. no CPUs share clock lines),
then the init() callback will get called once for each CPU.

> +
> +static int __init amd_cpufreq_init(void)
> +{
> +	int ret = 0;
> +
> +	/*
> +	 * Use only if:
> +	 * - AMD,
> +	 * - Family 17h (or) newer and,
> +	 * - Explicitly enabled
> +	 */
> +	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD ||
> +	    boot_cpu_data.x86 < 0x17 || !cppc_enable)
> +		return -ENODEV;
> +
> +	ret = cpufreq_register_driver(&amd_cpufreq_driver);
> +	if (ret) {
> +		pr_info("Failed to register driver\n");
> +		goto out;
> +	}
> +
> +	ret = amd_cpufreq_sysfs_expose_params();
> +	if (ret) {
> +		pr_info("Could not create sysfs entries\n");
> +		cpufreq_unregister_driver(&amd_cpufreq_driver);
> +		goto out;
> +	}
> +
> +	pr_info("Using amd-cpufreq driver\n");
> +	return ret;
> +
> +out:
> +	return ret;
> +}
> +
> +static void __exit amd_cpufreq_exit(void)
> +{
> +	amd_cpufreq_sysfs_delete_params();
> +	cpufreq_unregister_driver(&amd_cpufreq_driver);
> +}
> +
> +static const struct acpi_device_id amd_acpi_ids[] __used = {
> +	{ACPI_PROCESSOR_DEVICE_HID, },
> +	{}
> +};
> +
> +device_initcall(amd_cpufreq_init);
> +module_exit(amd_cpufreq_exit);
> +MODULE_DEVICE_TABLE(acpi, amd_acpi_ids);

All three should be placed directly below the struct/function they
represent without any blank lines in between. As suggested in
kernel documentation.

> +
> +MODULE_AUTHOR("Janakarajan Natarajan");
> +MODULE_DESCRIPTION("AMD CPUFreq driver based on ACPI CPPC v6.1 spec");
> +MODULE_LICENSE("GPL");

Should this be "GPL v2" ?

> -- 
> 2.17.1

-- 
viresh