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Subject: Re: [RFC 3/6] pseries/drcinfo: Pseries impl of arch_find_drc_info
To:     Michael Bringmann <mwb@linux.vnet.ibm.com>,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Cc:     Juliet Kim <minkim@us.ibm.com>,
        Thomas Falcon <tlfalcon@linux.vnet.ibm.com>,
        Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
References: <20181214204914.16435.59083.stgit@powerkvm6.aus.stglabs.ibm.com>
 <20181214205047.16435.19045.stgit@powerkvm6.aus.stglabs.ibm.com>
From:   Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Date:   Thu, 24 Jan 2019 16:04:37 -0800
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On 12/14/2018 12:51 PM, Michael Bringmann wrote:
> This patch provides a common interface to parse ibm,drc-indexes,
> ibm,drc-names, ibm,drc-types, ibm,drc-power-domains, or ibm,drc-info.
> The generic interface arch_find_drc_match is provided which accepts
> callback functions that may be applied to examine the data for each
> entry.
> 

The title of your patch is "pseries/drcinfo: Pseries impl of arch_find_drc_info"
but the name of the function you are ultimately implementing is
arch_find_drc_match if I'm not mistaken.

> Signed-off-by: Michael Bringmann <mwb@linux.vnet.ibm.com>
> ---
>  arch/powerpc/include/asm/prom.h             |    3 
>  arch/powerpc/platforms/pseries/of_helpers.c |  299 +++++++++++++++++++++++++++
>  include/linux/topology.h                    |    2 
>  3 files changed, 298 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/prom.h b/arch/powerpc/include/asm/prom.h
> index b04c5ce..910d1dc 100644
> --- a/arch/powerpc/include/asm/prom.h
> +++ b/arch/powerpc/include/asm/prom.h
> @@ -91,9 +91,6 @@ struct of_drc_info {
>  	u32 last_drc_index;
>  };
>  
> -extern int of_read_drc_info_cell(struct property **prop,
> -			const __be32 **curval, struct of_drc_info *data);
> -
>  
>  /*
>   * There are two methods for telling firmware what our capabilities are.
> diff --git a/arch/powerpc/platforms/pseries/of_helpers.c b/arch/powerpc/platforms/pseries/of_helpers.c
> index 0185e50..11c90cd 100644
> --- a/arch/powerpc/platforms/pseries/of_helpers.c
> +++ b/arch/powerpc/platforms/pseries/of_helpers.c
> @@ -1,5 +1,7 @@
>  // SPDX-License-Identifier: GPL-2.0
>  
> +#define pr_fmt(fmt) "drc: " fmt
> +
>  #include <linux/string.h>
>  #include <linux/err.h>
>  #include <linux/slab.h>
> @@ -11,6 +13,12 @@
>  
>  #define	MAX_DRC_NAME_LEN 64
>  
> +static int drc_debug;
> +#define dbg(args...) if (drc_debug) { printk(KERN_DEBUG args); }
> +#define err(arg...) printk(KERN_ERR args);
> +#define info(arg...) printk(KERN_INFO args);
> +#define warn(arg...) printk(KERN_WARNING args);

Its pretty standard these days to use the pr_debug, pr_err, pr_info, pr_warn
variations over printk(LEVEL args).

> +
>  /**
>   * pseries_of_derive_parent - basically like dirname(1)
>   * @path:  the full_name of a node to be added to the tree
> @@ -46,7 +54,8 @@ struct device_node *pseries_of_derive_parent(const char *path)
>  
>  /* Helper Routines to convert between drc_index to cpu numbers */
>  
> -int of_read_drc_info_cell(struct property **prop, const __be32 **curval,
> +static int of_read_drc_info_cell(struct property **prop,
> +			const __be32 **curval,
>  			struct of_drc_info *data)
>  {
>  	const char *p;
> @@ -90,4 +99,290 @@ int of_read_drc_info_cell(struct property **prop, const __be32 **curval,
>  
>  	return 0;
>  }
> -EXPORT_SYMBOL(of_read_drc_info_cell);
> +
> +static int walk_drc_info(struct device_node *dn,
> +		bool (*usercb)(struct of_drc_info *drc,
> +				void *data,
> +				int *ret_code),
> +		char *opt_drc_type,
> +		void *data)
> +{
> +	struct property *info;
> +	unsigned int entries;
> +	struct of_drc_info drc;
> +	const __be32 *value;
> +	int j, ret_code = -EINVAL;
> +	bool done = false;
> +
> +	info = of_find_property(dn, "ibm,drc-info", NULL);
> +	if (info == NULL)
> +		return -EINVAL;
> +
> +	value = info->value;
> +	entries = of_read_number(value++, 1);
> +
> +	for (j = 0, done = 0; (j < entries) && (!done); j++) {
> +		of_read_drc_info_cell(&info, &value, &drc);
> +
> +		if (opt_drc_type && strcmp(opt_drc_type, drc.drc_type))
> +			continue;
> +
> +		done = usercb(&drc, data, &ret_code);
> +	}
> +
> +	return ret_code;
> +}
> +
> +static int get_children_props(struct device_node *dn, const int **drc_indexes,
> +		const int **drc_names, const int **drc_types,
> +		const int **drc_power_domains)
> +{
> +	const int *indexes, *names, *types, *domains;
> +
> +	indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
> +	names = of_get_property(dn, "ibm,drc-names", NULL);
> +	types = of_get_property(dn, "ibm,drc-types", NULL);
> +	domains = of_get_property(dn, "ibm,drc-power-domains", NULL);
> +
> +	if (!indexes || !names || !types || !domains) {
> +		/* Slot does not have dynamically-removable children */
> +		return -EINVAL;
> +	}
> +	if (drc_indexes)
> +		*drc_indexes = indexes;
> +	if (drc_names)
> +		/* &drc_names[1] contains NULL terminated slot names */
> +		*drc_names = names;
> +	if (drc_types)
> +		/* &drc_types[1] contains NULL terminated slot types */
> +		*drc_types = types;
> +	if (drc_power_domains)
> +		*drc_power_domains = domains;
> +
> +	return 0;
> +}
> +
> +static int is_php_type(char *drc_type)
> +{
> +	unsigned long value;
> +	char *endptr;
> +
> +	/* PCI Hotplug nodes have an integer for drc_type */
> +	value = simple_strtoul(drc_type, &endptr, 10);
> +	if (endptr == drc_type)
> +		return 0;
> +
> +	return 1;
> +}
> +
> +/**
> + * is_php_dn() - return 1 if this is a hotpluggable pci slot, else 0
> + * @dn: target &device_node
> + * @indexes: passed to get_children_props()
> + * @names: passed to get_children_props()
> + * @types: returned from get_children_props()
> + * @power_domains:
> + *
> + * This routine will return true only if the device node is
> + * a hotpluggable slot. This routine will return false
> + * for built-in pci slots (even when the built-in slots are
> + * dlparable.)
> + */
> +static int is_php_dn(struct device_node *dn, const int **indexes,
> +		const int **names, const int **types,
> +		const int **power_domains)
> +{
> +	const int *drc_types;
> +	int rc;
> +
> +	rc = get_children_props(dn, indexes, names, &drc_types,
> +				power_domains);
> +	if (rc < 0)
> +		return 0;
> +
> +	if (!is_php_type((char *) &drc_types[1]))
> +		return 0;
> +
> +	*types = drc_types;
> +	return 1;
> +}
> +
> +struct find_drc_match_cb_struct {
> +	struct device_node *dn;
> +	bool (*usercb)(struct device_node *dn,
> +			u32 drc_index, char *drc_name,
> +			char *drc_type, u32 drc_power_domain,
> +			void *data);
> +	char *drc_type;
> +	char *drc_name;
> +	u32 drc_index;
> +	bool match_drc_index;
> +	bool add_slot;
> +	void *data;
> +};
> +
> +static int find_drc_match_v1(struct device_node *dn, void *data)
> +{
> +	struct find_drc_match_cb_struct *cdata = data;
> +	int i, retval = 0;
> +	const int *indexes, *names, *types, *domains;
> +	char *name, *type;
> +	struct device_node *root = dn;
> +
> +	if (cdata->match_drc_index)
> +		root = dn->parent;
> +
> +	if (cdata->add_slot) {
> +		/* If this is not a hotplug slot, return without doing
> +		 * anything.
> +		 */
> +		if (!is_php_dn(root, &indexes, &names, &types, &domains))
> +			return 0;
> +	} else {
> +		if (get_children_props(root, &indexes, &names, &types,
> +			&domains) < 0)
> +			return 0;
> +	}
> +
> +	dbg("Entry %s: dn=%pOF\n", __func__, dn);
> +
> +	name = (char *) &names[1];
> +	type = (char *) &types[1];
> +	for (i = 0; i < be32_to_cpu(indexes[0]); i++) {
> +
> +		if (cdata->match_drc_index &&
> +			((unsigned int) indexes[i + 1] != cdata->drc_index)) {
> +			name += strlen(name) + 1;
> +			type += strlen(type) + 1;
> +			continue;
> +		}
> +
> +		if (((cdata->drc_name == NULL) ||
> +		     (cdata->drc_name && !strcmp(cdata->drc_name, name))) &&
> +		    ((cdata->drc_type == NULL) ||
> +		     (cdata->drc_type && !strcmp(cdata->drc_type, type)))) {
> +
> +			if (cdata->usercb) {
> +				retval = cdata->usercb(dn,
> +					be32_to_cpu(indexes[i + 1]),
> +					name, type,
> +					be32_to_cpu(domains[i + 1]),
> +					cdata->data);
> +				if (!retval)
> +					return retval;
> +			} else {
> +				return 0;
> +			}
> +		}
> +
> +		name += strlen(name) + 1;
> +		type += strlen(type) + 1;
> +	}
> +
> +	dbg("%s - Exit: rc[%d]\n", __func__, retval);
> +
> +	/* XXX FIXME: reports a failure only if last entry in loop failed */
> +	return retval;
> +}
> +
> +static bool find_drc_match_v2_cb(struct of_drc_info *drc, void *data,
> +				int *ret_code)
> +{
> +	struct find_drc_match_cb_struct *cdata = data;
> +	u32 drc_index;
> +	char drc_name[MAX_DRC_NAME_LEN];
> +	int i, retval;
> +
> +	(*ret_code) = -EINVAL;
> +
> +	/* This set not a PHP type? */
> +	if (cdata->add_slot) {
> +		if (!is_php_type((char *) drc->drc_type)) {
> +			return false;
> +		}
> +	}
> +
> +	/* Anything to use from this set? */
> +	if (cdata->match_drc_index && (cdata->drc_index > drc->last_drc_index))
> +		return false;
> +	if ((cdata->drc_type && strcmp(cdata->drc_type, drc->drc_type))
> +		return false;
> +
> +	/* Check the drc-index entries of this set */
> +	for (i = 0, drc_index = drc->drc_index_start;
> +		i < drc->num_sequential_elems; i++, drc_index++) {
> +
> +		if (cdata->match_drc_index && (cdata->drc_index != drc_index))
> +			continue;
> +
> +		sprintf(drc_name, "%s%d", drc->drc_name_prefix,
> +			drc_index - drc->drc_index_start +
> +			drc->drc_name_suffix_start);
> +
> +		if ((cdata->drc_name == NULL) ||
> +		    (cdata->drc_name && !strcmp(cdata->drc_name, drc_name))) {
> +
> +			if (cdata->usercb) {
> +				retval = cdata->usercb(cdata->dn,
> +						drc_index, drc_name,
> +						drc->drc_type,
> +						drc->drc_power_domain,
> +						cdata->data);
> +				if (!retval) {
> +					(*ret_code) = retval;
> +					return true;
> +				}
> +			} else {
> +				(*ret_code) = 0;
> +				return true;
> +			}
> +		}
> +	}
> +
> +	(*ret_code) = retval;
> +	return false;
> +}
> +
> +static int find_drc_match_v2(struct device_node *dn, void *data)
> +{
> +	struct find_drc_match_cb_struct *cdata = data;
> +	struct device_node *root = cdata->dn;
> +
> +	if (!cdata->add_slot) {
> +		if (!cdata->drc_type ||
> +			(cdata->drc_type && strcmp(cdata->drc_type, "SLOT")))
> +			root = dn->parent;
> +	}
> +
> +	return walk_drc_info(root, find_drc_match_v2_cb, NULL, data);
> +}
> +
> +int arch_find_drc_match(struct device_node *dn,
> +			bool (*usercb)(struct device_node *dn,
> +				u32 drc_index, char *drc_name,
> +				char *drc_type, u32 drc_power_domain,
> +				void *data),
> +			char *opt_drc_type, char *opt_drc_name,
> +			bool match_drc_index, bool add_slot,
> +			void *data)
> +{
> +	struct find_drc_match_cb_struct cdata = { dn, usercb,
> +			opt_drc_type, opt_drc_name, 0,
> +			match_drc_index, add_slot, data };
> +
> +	if (match_drc_index) {
> +		const int *my_index =
> +			of_get_property(dn, "ibm,my-drc-index", NULL);
> +		if (!my_index) {
> +			/* Node isn't DLPAR/hotplug capable */
> +			return -EINVAL;
> +		}
> +		cdata.drc_index = *my_index;
> +	}
> +
> +	if (firmware_has_feature(FW_FEATURE_DRC_INFO))
> +		return find_drc_match_v2(dn, &cdata);
> +	else
> +		return find_drc_match_v1(dn, &cdata);
> +}
> +EXPORT_SYMBOL(arch_find_drc_match);
> diff --git a/include/linux/topology.h b/include/linux/topology.h
> index df97f5f..c3dfa53 100644
> --- a/include/linux/topology.h
> +++ b/include/linux/topology.h
> @@ -50,7 +50,7 @@ int arch_find_drc_match(struct device_node *dn,
>  				char *drc_type, u32 drc_power_domain,
>  				void *data),
>  			char *opt_drc_type, char *opt_drc_name,
> -			bool match_drc_index, bool ck_php_type,
> +			bool match_drc_index, bool add_slot,
>  			void *data);

Why are you making a change to the prototype here? You should just define it in
your first patch instead of touching it again here.

-Tyrel

>  
>  /* Conform to ACPI 2.0 SLIT distance definitions */
>