Subject: Re: [PATCH V9 1/3] powernv: powercap: Add support for powercap framework

From: Cyril Bur <[email-masked]>
Date: Mon, 31 Jul 2017 14:54:56 +1000

On Mon, 2017-07-31 at 07:54 +0530, Shilpasri G Bhat wrote:
> Adds a generic powercap framework to change the system powercap
> inband through OPAL-OCC command/response interface.
> 
> Signed-off-by: Shilpasri G Bhat <[email-masked]>
> ---
> Changes from V8:
> - Use __pa() while passing pointer in opal call
> - Use mutex_lock_interruptible()
> - Fix error codes returned to user
> - Allocate and add sysfs attributes in a single loop
> 
>  arch/powerpc/include/asm/opal-api.h            |   5 +-
>  arch/powerpc/include/asm/opal.h                |   4 +
>  arch/powerpc/platforms/powernv/Makefile        |   2 +-
>  arch/powerpc/platforms/powernv/opal-powercap.c | 243 +++++++++++++++++++++++++
>  arch/powerpc/platforms/powernv/opal-wrappers.S |   2 +
>  arch/powerpc/platforms/powernv/opal.c          |   4 +
>  6 files changed, 258 insertions(+), 2 deletions(-)
>  create mode 100644 arch/powerpc/platforms/powernv/opal-powercap.c
> 
> diff --git a/arch/powerpc/include/asm/opal-api.h b/arch/powerpc/include/asm/opal-api.h
> index 3130a73..c3e0c4a 100644
> --- a/arch/powerpc/include/asm/opal-api.h
> +++ b/arch/powerpc/include/asm/opal-api.h
> @@ -42,6 +42,7 @@
>  #define OPAL_I2C_STOP_ERR	-24
>  #define OPAL_XIVE_PROVISIONING	-31
>  #define OPAL_XIVE_FREE_ACTIVE	-32
> +#define OPAL_TIMEOUT		-33
>  
>  /* API Tokens (in r0) */
>  #define OPAL_INVALID_CALL		       -1
> @@ -190,7 +191,9 @@
>  #define OPAL_NPU_INIT_CONTEXT			146
>  #define OPAL_NPU_DESTROY_CONTEXT		147
>  #define OPAL_NPU_MAP_LPAR			148
> -#define OPAL_LAST				148
> +#define OPAL_GET_POWERCAP			152
> +#define OPAL_SET_POWERCAP			153
> +#define OPAL_LAST				153
>  
>  /* Device tree flags */
>  
> diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
> index 588fb1c..ec2087c 100644
> --- a/arch/powerpc/include/asm/opal.h
> +++ b/arch/powerpc/include/asm/opal.h
> @@ -267,6 +267,8 @@ int64_t opal_xive_set_vp_info(uint64_t vp,
>  int64_t opal_xive_free_irq(uint32_t girq);
>  int64_t opal_xive_sync(uint32_t type, uint32_t id);
>  int64_t opal_xive_dump(uint32_t type, uint32_t id);
> +int opal_get_powercap(u32 handle, int token, u32 *pcap);
> +int opal_set_powercap(u32 handle, int token, u32 pcap);
>  
>  /* Internal functions */
>  extern int early_init_dt_scan_opal(unsigned long node, const char *uname,
> @@ -345,6 +347,8 @@ static inline int opal_get_async_rc(struct opal_msg msg)
>  
>  void opal_wake_poller(void);
>  
> +void opal_powercap_init(void);
> +
>  #endif /* __ASSEMBLY__ */
>  
>  #endif /* _ASM_POWERPC_OPAL_H */
> diff --git a/arch/powerpc/platforms/powernv/Makefile b/arch/powerpc/platforms/powernv/Makefile
> index b5d98cb..e79f806 100644
> --- a/arch/powerpc/platforms/powernv/Makefile
> +++ b/arch/powerpc/platforms/powernv/Makefile
> @@ -2,7 +2,7 @@ obj-y			+= setup.o opal-wrappers.o opal.o opal-async.o idle.o
>  obj-y			+= opal-rtc.o opal-nvram.o opal-lpc.o opal-flash.o
>  obj-y			+= rng.o opal-elog.o opal-dump.o opal-sysparam.o opal-sensor.o
>  obj-y			+= opal-msglog.o opal-hmi.o opal-power.o opal-irqchip.o
> -obj-y			+= opal-kmsg.o
> +obj-y			+= opal-kmsg.o opal-powercap.o
>  
>  obj-$(CONFIG_SMP)	+= smp.o subcore.o subcore-asm.o
>  obj-$(CONFIG_PCI)	+= pci.o pci-ioda.o npu-dma.o
> diff --git a/arch/powerpc/platforms/powernv/opal-powercap.c b/arch/powerpc/platforms/powernv/opal-powercap.c
> new file mode 100644
> index 0000000..9be5093
> --- /dev/null
> +++ b/arch/powerpc/platforms/powernv/opal-powercap.c
> @@ -0,0 +1,243 @@
> +/*
> + * PowerNV OPAL Powercap interface
> + *
> + * Copyright 2017 IBM Corp.
> + *
> + * 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.
> + */
> +
> +#define pr_fmt(fmt)     "opal-powercap: " fmt
> +
> +#include <linux/of.h>
> +#include <linux/kobject.h>
> +#include <linux/slab.h>
> +
> +#include <asm/opal.h>
> +
> +DEFINE_MUTEX(powercap_mutex);
> +
> +static struct kobject *powercap_kobj;
> +
> +struct powercap_attr {
> +	u32 handle;
> +	struct kobj_attribute attr;
> +};
> +
> +static struct pcap {
> +	struct attribute_group pg;
> +	struct powercap_attr *pattrs;
> +} *pcaps;
> +
> +static ssize_t powercap_show(struct kobject *kobj, struct kobj_attribute *attr,
> +			     char *buf)
> +{
> +	struct powercap_attr *pcap_attr = container_of(attr,
> +						struct powercap_attr, attr);
> +	struct opal_msg msg;
> +	u32 pcap;
> +	int ret, token;
> +
> +	token = opal_async_get_token_interruptible();
> +	if (token < 0) {
> +		pr_devel("Failed to get token\n");
> +		return token;
> +	}
> +
> +	ret = mutex_lock_interruptible(&powercap_mutex);
> +	if (ret)

You'll need to release the token here.

> +		return ret;
> +
> +	ret = opal_get_powercap(pcap_attr->handle, token, (u32 *)__pa(&pcap));
> +	switch (ret) {
> +	case OPAL_ASYNC_COMPLETION:
> +		ret = opal_async_wait_response(token, &msg);
> +		if (ret) {
> +			pr_devel("Failed to wait for the async response\n");
> +			ret = -EIO;
> +			goto out;
> +		}
> +		ret = opal_error_code(opal_get_async_rc(msg));
> +		if (!ret) {
> +			ret = sprintf(buf, "%u\n", be32_to_cpu(pcap));
> +			if (ret < 0)
> +				ret = -EIO;
> +		}
> +		break;
> +	case OPAL_SUCCESS:
> +		ret = sprintf(buf, "%u\n", be32_to_cpu(pcap));
> +		if (ret < 0)
> +			ret = -EIO;
> +		break;
> +	default:
> +		ret = opal_error_code(ret);
> +	}
> +
> +out:
> +	mutex_unlock(&powercap_mutex);
> +	opal_async_release_token(token);
> +	return ret;
> +}
> +
> +static ssize_t powercap_store(struct kobject *kobj,
> +			      struct kobj_attribute *attr, const char *buf,
> +			      size_t count)
> +{
> +	struct powercap_attr *pcap_attr = container_of(attr,
> +						struct powercap_attr, attr);
> +	struct opal_msg msg;
> +	u32 pcap;
> +	int ret, token;
> +
> +	ret = kstrtoint(buf, 0, &pcap);
> +	if (ret)
> +		return ret;
> +
> +	token = opal_async_get_token_interruptible();
> +	if (token < 0) {
> +		pr_devel("Failed to get token\n");
> +		return token;
> +	}
> +
> +	ret = mutex_lock_interruptible(&powercap_mutex);
> +	if (ret)

You'll need to release the token here.

> +		return ret;
> +
> +	ret = opal_set_powercap(pcap_attr->handle, token, pcap);
> +	switch (ret) {
> +	case OPAL_ASYNC_COMPLETION:
> +		ret = opal_async_wait_response(token, &msg);
> +		if (ret) {
> +			pr_devel("Failed to wait for the async response\n");
> +			ret = -EIO;
> +			goto out;
> +		}
> +		ret = opal_error_code(opal_get_async_rc(msg));
> +		if (!ret)
> +			ret = count;
> +		break;
> +	case OPAL_SUCCESS:
> +		ret = count;
> +		break;
> +	default:
> +		ret = opal_error_code(ret);
> +	}
> +
> +out:
> +	mutex_unlock(&powercap_mutex);
> +	opal_async_release_token(token);
> +
> +	return ret;
> +}
> +
> +static void powercap_add_attr(int handle, const char *name,
> +			      struct powercap_attr *attr)
> +{
> +	attr->handle = handle;
> +	sysfs_attr_init(&attr->attr.attr);
> +	attr->attr.attr.name = name;
> +	attr->attr.attr.mode = 0444;
> +	attr->attr.show = powercap_show;
> +}
> +
> +void __init opal_powercap_init(void)
> +{
> +	struct device_node *powercap, *node;
> +	int i = 0;
> +
> +	powercap = of_find_compatible_node(NULL, NULL, "ibm,opal-powercap");
> +	if (!powercap) {
> +		pr_devel("Powercap node not found\n");
> +		return;
> +	}
> +
> +	pcaps = kcalloc(of_get_child_count(powercap), sizeof(*pcaps),
> +			GFP_KERNEL);
> +	if (!pcaps)
> +		return;
> +
> +	powercap_kobj = kobject_create_and_add("powercap", opal_kobj);
> +	if (!powercap_kobj) {
> +		pr_warn("Failed to create powercap kobject\n");
> +		goto out_pcaps;
> +	}
> +
> +	i = 0;
> +	for_each_child_of_node(powercap, node) {
> +		u32 cur, min, max;
> +		int j = 0;
> +		bool has_cur = false, has_min = false, has_max = false;
> +
> +		if (!of_property_read_u32(node, "powercap-min", &min)) {
> +			j++;
> +			has_min = true;
> +		}
> +
> +		if (!of_property_read_u32(node, "powercap-max", &max)) {
> +			j++;
> +			has_max = true;
> +		}
> +
> +		if (!of_property_read_u32(node, "powercap-current", &cur)) {
> +			j++;
> +			has_cur = true;
> +		}
> +
> +		pcaps[i].pattrs = kcalloc(j, sizeof(struct powercap_attr),
> +					  GFP_KERNEL);
> +		if (!pcaps[i].pattrs)
> +			goto out_pcaps_pattrs;
> +
> +		pcaps[i].pg.attrs = kcalloc(j + 1, sizeof(struct attribute *),
> +					    GFP_KERNEL);
> +		if (!pcaps[i].pg.attrs) {
> +			kfree(pcaps[i].pattrs);
> +			goto out_pcaps_pattrs;
> +		}
> +
> +		j = 0;
> +		pcaps[i].pg.name = node->name;
> +		if (has_min) {
> +			powercap_add_attr(min, "powercap-min",
> +					  &pcaps[i].pattrs[j]);
> +			pcaps[i].pg.attrs[j] = &pcaps[i].pattrs[j].attr.attr;
> +			j++;
> +		}
> +
> +		if (has_max) {
> +			powercap_add_attr(max, "powercap-max",
> +					  &pcaps[i].pattrs[j]);
> +			pcaps[i].pg.attrs[j] = &pcaps[i].pattrs[j].attr.attr;
> +			j++;
> +		}
> +
> +		if (has_cur) {
> +			powercap_add_attr(cur, "powercap-current",
> +					  &pcaps[i].pattrs[j]);
> +			pcaps[i].pattrs[j].attr.attr.mode |= 0220;
> +			pcaps[i].pattrs[j].attr.store = powercap_store;
> +			pcaps[i].pg.attrs[j] = &pcaps[i].pattrs[j].attr.attr;
> +			j++;
> +		}
> +
> +		if (sysfs_create_group(powercap_kobj, &pcaps[i].pg)) {
> +			pr_warn("Failed to create powercap attribute group %s\n",
> +				pcaps[i].pg.name);
> +			goto out_pcaps_pattrs;
> +		}
> +		i++;
> +	}
> +
> +	return;
> +
> +out_pcaps_pattrs:
> +	while (--i >= 0) {
> +		kfree(pcaps[i].pattrs);
> +		kfree(pcaps[i].pg.attrs);
> +	}
> +	kobject_put(powercap_kobj);
> +out_pcaps:
> +	kfree(pcaps);
> +}
> diff --git a/arch/powerpc/platforms/powernv/opal-wrappers.S b/arch/powerpc/platforms/powernv/opal-wrappers.S
> index 4ca6c26..eff5fe7 100644
> --- a/arch/powerpc/platforms/powernv/opal-wrappers.S
> +++ b/arch/powerpc/platforms/powernv/opal-wrappers.S
> @@ -310,3 +310,5 @@ OPAL_CALL(opal_xive_dump,			OPAL_XIVE_DUMP);
>  OPAL_CALL(opal_npu_init_context,		OPAL_NPU_INIT_CONTEXT);
>  OPAL_CALL(opal_npu_destroy_context,		OPAL_NPU_DESTROY_CONTEXT);
>  OPAL_CALL(opal_npu_map_lpar,			OPAL_NPU_MAP_LPAR);
> +OPAL_CALL(opal_get_powercap,			OPAL_GET_POWERCAP);
> +OPAL_CALL(opal_set_powercap,			OPAL_SET_POWERCAP);
> diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
> index cad6b57..889da97 100644
> --- a/arch/powerpc/platforms/powernv/opal.c
> +++ b/arch/powerpc/platforms/powernv/opal.c
> @@ -836,6 +836,9 @@ static int __init opal_init(void)
>  	/* Initialise OPAL kmsg dumper for flushing console on panic */
>  	opal_kmsg_init();
>  
> +	/* Initialise OPAL powercap interface */
> +	opal_powercap_init();
> +
>  	return 0;
>  }
>  machine_subsys_initcall(powernv, opal_init);
> @@ -952,6 +955,7 @@ int opal_error_code(int rc)
>  	case OPAL_UNSUPPORTED:		return -EIO;
>  	case OPAL_HARDWARE:		return -EIO;
>  	case OPAL_INTERNAL_ERROR:	return -EIO;
> +	case OPAL_TIMEOUT:		return -ETIMEDOUT;
>  	default:
>  		pr_err("%s: unexpected OPAL error %d\n", __func__, rc);
>  		return -EIO;