Subject: Re: [PATCH V8 2/3] powernv: Add support to set power-shifting-ratio

From: Cyril Bur <[email-masked]>
Date: Fri, 28 Jul 2017 14:15:42 +1000

On Wed, 2017-07-26 at 10:35 +0530, Shilpasri G Bhat wrote:
> This patch adds support to set power-shifting-ratio for CPU-GPU which
> is used by OCC power capping algorithm.
> 
> Signed-off-by: Shilpasri G Bhat <[email-masked]>

Hi Shilpasri,

I started looking though this - a lot the comments to patch 1/3 apply
here so I'll stop repeating myself :).

Thanks,

Cyril
> ---
> Changes from V7:
> - Replaced sscanf with kstrtoint
> 
>  arch/powerpc/include/asm/opal-api.h            |   4 +-
>  arch/powerpc/include/asm/opal.h                |   3 +
>  arch/powerpc/platforms/powernv/Makefile        |   2 +-
>  arch/powerpc/platforms/powernv/opal-psr.c      | 169 +++++++++++++++++++++++++
>  arch/powerpc/platforms/powernv/opal-wrappers.S |   2 +
>  arch/powerpc/platforms/powernv/opal.c          |   3 +
>  6 files changed, 181 insertions(+), 2 deletions(-)
>  create mode 100644 arch/powerpc/platforms/powernv/opal-psr.c
> 
> diff --git a/arch/powerpc/include/asm/opal-api.h b/arch/powerpc/include/asm/opal-api.h
> index c3e0c4a..0d37315 100644
> --- a/arch/powerpc/include/asm/opal-api.h
> +++ b/arch/powerpc/include/asm/opal-api.h
> @@ -193,7 +193,9 @@
>  #define OPAL_NPU_MAP_LPAR			148
>  #define OPAL_GET_POWERCAP			152
>  #define OPAL_SET_POWERCAP			153
> -#define OPAL_LAST				153
> +#define OPAL_GET_PSR				154
> +#define OPAL_SET_PSR				155
> +#define OPAL_LAST				155
>  
>  /* Device tree flags */
>  
> diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
> index ec2087c..58b30a4 100644
> --- a/arch/powerpc/include/asm/opal.h
> +++ b/arch/powerpc/include/asm/opal.h
> @@ -269,6 +269,8 @@ int64_t opal_xive_set_vp_info(uint64_t vp,
>  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);
> +int opal_get_power_shifting_ratio(u32 handle, int token, u32 *psr);
> +int opal_set_power_shifting_ratio(u32 handle, int token, u32 psr);
>  
>  /* Internal functions */
>  extern int early_init_dt_scan_opal(unsigned long node, const char *uname,
> @@ -348,6 +350,7 @@ static inline int opal_get_async_rc(struct opal_msg msg)
>  void opal_wake_poller(void);
>  
>  void opal_powercap_init(void);
> +void opal_psr_init(void);
>  
>  #endif /* __ASSEMBLY__ */
>  
> diff --git a/arch/powerpc/platforms/powernv/Makefile b/arch/powerpc/platforms/powernv/Makefile
> index e79f806..9ed7d33 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 opal-powercap.o
> +obj-y			+= opal-kmsg.o opal-powercap.o opal-psr.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-psr.c b/arch/powerpc/platforms/powernv/opal-psr.c
> new file mode 100644
> index 0000000..07e3f78
> --- /dev/null
> +++ b/arch/powerpc/platforms/powernv/opal-psr.c
> @@ -0,0 +1,169 @@
> +/*
> + * PowerNV OPAL Power-Shifting-Ratio 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-psr: " fmt
> +
> +#include <linux/of.h>
> +#include <linux/kobject.h>
> +#include <linux/slab.h>
> +
> +#include <asm/opal.h>
> +
> +DEFINE_MUTEX(psr_mutex);
> +
> +static struct kobject *psr_kobj;
> +
> +struct psr_attr {
> +	u32 handle;
> +	struct kobj_attribute attr;
> +};
> +
> +static struct psr_attr *psr_attrs;
> +static struct kobject *psr_kobj;
> +
> +static ssize_t psr_show(struct kobject *kobj, struct kobj_attribute *attr,
> +			char *buf)
> +{
> +	struct psr_attr *psr_attr = container_of(attr, struct psr_attr, attr);
> +	struct opal_msg msg;
> +	int psr, ret, token;
> +
> +	token = opal_async_get_token_interruptible();
> +	if (token < 0) {
> +		pr_devel("Failed to get token\n");
> +		return token;
> +	}
> +
> +	mutex_lock(&psr_mutex);
> +	ret = opal_get_power_shifting_ratio(psr_attr->handle, token, &psr);

__pa()

> +	switch (ret) {
> +	case OPAL_ASYNC_COMPLETION:
> +		ret = opal_async_wait_response(token, &msg);
> +		if (ret) {
> +			pr_devel("Failed to wait for the async response %d\n",
> +				 ret);
> +			goto out;
> +		}
> +		ret = opal_error_code(opal_get_async_rc(msg));
> +		if (!ret)
> +			ret = sprintf(buf, "%u\n", be32_to_cpu(psr));
> +		break;
> +	case OPAL_SUCCESS:
> +		ret = sprintf(buf, "%u\n", be32_to_cpu(psr));
> +		break;
> +	default:
> +		ret = opal_error_code(ret);
> +	}
> +
> +out:
> +	mutex_unlock(&psr_mutex);
> +	opal_async_release_token(token);

Same comment as previous patch - I don't know if returning the -EINVAL
from opal_async_wait_response()... we should probably start deciding at
a higher level what to do...

> +	return ret;
> +}
> +
> +static ssize_t psr_store(struct kobject *kobj, struct kobj_attribute *attr,
> +			 const char *buf, size_t count)
> +{
> +	struct psr_attr *psr_attr = container_of(attr, struct psr_attr, attr);
> +	struct opal_msg msg;
> +	int psr, ret, token;
> +
> +	ret = kstrtoint(buf, 0, &psr);
> +	if (ret)
> +		return ret;
> +
> +	token = opal_async_get_token_interruptible();
> +	if (token < 0) {
> +		pr_devel("Failed to get token\n");
> +		return token;
> +	}
> +
> +	mutex_lock(&psr_mutex);
> +	ret = opal_set_power_shifting_ratio(psr_attr->handle, token, psr);
> +	switch (ret) {
> +	case OPAL_ASYNC_COMPLETION:
> +		ret = opal_async_wait_response(token, &msg);
> +		if (ret) {
> +			pr_devel("Failed to wait for the async response %d\n",
> +				 ret);
> +			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(&psr_mutex);
> +	opal_async_release_token(token);
> +
> +	return ret;
> +}
> +
> +void __init opal_psr_init(void)
> +{
> +	struct device_node *psr, *node;
> +	int psr_attr_count = 0, i = 0;
> +
> +	psr = of_find_node_by_path("/ibm,opal/power-mgt/psr");
> +	if (!psr) {
> +		pr_devel("/ibm,opal/power-mgt/psr node not found\n");
> +		return;
> +	}
> +
> +	for_each_child_of_node(psr, node)
> +		psr_attr_count++;
> +
> +	psr_attrs = kcalloc(psr_attr_count, sizeof(struct psr_attr),
> +			    GFP_KERNEL);
> +	if (!psr_attrs)
> +		return;
> +
> +	for_each_child_of_node(psr, node) {
> +		if (of_property_read_u32(node, "handle",
> +					 &psr_attrs[i].handle))
> +			goto out;
> +
> +		sysfs_attr_init(&psr_attrs[i].attr.attr);
> +		if (of_property_read_string(node, "label",
> +					    &psr_attrs[i].attr.attr.name))
> +			goto out;
> +		psr_attrs[i].attr.attr.mode = 0664;
> +		psr_attrs[i].attr.show = psr_show;
> +		psr_attrs[i].attr.store = psr_store;
> +		i++;
> +	}
> +
> +	psr_kobj = kobject_create_and_add("psr", opal_kobj);
> +	if (!psr_kobj) {
> +		pr_warn("Failed to create psr kobkect\n");

Typo

> +		goto out;
> +	}
> +
> +	for (i = 0; i < psr_attr_count; i++)
> +		if (sysfs_create_file(psr_kobj, &psr_attrs[i].attr.attr)) {
> +			pr_devel("Failed to create sysfs file %s\n",
> +				 psr_attrs[i].attr.attr.name);
> +			goto out_kobj;
> +

Can't we do all that in the first loop?

> 		}
> +
> +	return;
> +out_kobj:
> +	kobject_put(psr_kobj);
> +out:
> +	kfree(psr_attrs);
> +}
> diff --git a/arch/powerpc/platforms/powernv/opal-wrappers.S b/arch/powerpc/platforms/powernv/opal-wrappers.S
> index eff5fe7..9867726 100644
> --- a/arch/powerpc/platforms/powernv/opal-wrappers.S
> +++ b/arch/powerpc/platforms/powernv/opal-wrappers.S
> @@ -312,3 +312,5 @@ 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);
> +OPAL_CALL(opal_get_power_shifting_ratio,	OPAL_GET_PSR);
> +OPAL_CALL(opal_set_power_shifting_ratio,	OPAL_SET_PSR);
> diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
> index 889da97..280a736 100644
> --- a/arch/powerpc/platforms/powernv/opal.c
> +++ b/arch/powerpc/platforms/powernv/opal.c
> @@ -839,6 +839,9 @@ static int __init opal_init(void)
>  	/* Initialise OPAL powercap interface */
>  	opal_powercap_init();
>  
> +	/* Initialise OPAL Power-Shifting-Ratio interface */
> +	opal_psr_init();
> +
>  	return 0;
>  }
>  machine_subsys_initcall(powernv, opal_init);