[linux-block.git] / include / net / dsa.h

/*
 * include/net/dsa.h - Driver for Distributed Switch Architecture switch chips
 * Copyright (c) 2008-2009 Marvell Semiconductor
 *
 * 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.
 */

#ifndef __LINUX_NET_DSA_H
#define __LINUX_NET_DSA_H

#include <linux/if_ether.h>
#include <linux/list.h>
#include <linux/timer.h>
#include <linux/workqueue.h>
#include <linux/of.h>
#include <linux/phy.h>
#include <linux/phy_fixed.h>
#include <linux/ethtool.h>

enum dsa_tag_protocol {
	DSA_TAG_PROTO_NONE = 0,
	DSA_TAG_PROTO_DSA,
	DSA_TAG_PROTO_TRAILER,
	DSA_TAG_PROTO_EDSA,
	DSA_TAG_PROTO_BRCM,
};

#define DSA_MAX_SWITCHES	4
#define DSA_MAX_PORTS		12

struct dsa_chip_data {
	/*
	 * How to access the switch configuration registers.
	 */
	struct device	*host_dev;
	int		sw_addr;

	/* set to size of eeprom if supported by the switch */
	int		eeprom_len;

	/* Device tree node pointer for this specific switch chip
	 * used during switch setup in case additional properties
	 * and resources needs to be used
	 */
	struct device_node *of_node;

	/*
	 * The names of the switch's ports.  Use "cpu" to
	 * designate the switch port that the cpu is connected to,
	 * "dsa" to indicate that this port is a DSA link to
	 * another switch, NULL to indicate the port is unused,
	 * or any other string to indicate this is a physical port.
	 */
	char		*port_names[DSA_MAX_PORTS];
	struct device_node *port_dn[DSA_MAX_PORTS];

	/*
	 * An array (with nr_chips elements) of which element [a]
	 * indicates which port on this switch should be used to
	 * send packets to that are destined for switch a.  Can be
	 * NULL if there is only one switch chip.
	 */
	s8		*rtable;
};

struct dsa_platform_data {
	/*
	 * Reference to a Linux network interface that connects
	 * to the root switch chip of the tree.
	 */
	struct device	*netdev;
	struct net_device *of_netdev;

	/*
	 * Info structs describing each of the switch chips
	 * connected via this network interface.
	 */
	int		nr_chips;
	struct dsa_chip_data	*chip;
};

struct packet_type;

struct dsa_switch_tree {
	/*
	 * Configuration data for the platform device that owns
	 * this dsa switch tree instance.
	 */
	struct dsa_platform_data	*pd;

	/*
	 * Reference to network device to use, and which tagging
	 * protocol to use.
	 */
	struct net_device	*master_netdev;
	int			(*rcv)(struct sk_buff *skb,
				       struct net_device *dev,
				       struct packet_type *pt,
				       struct net_device *orig_dev);
	enum dsa_tag_protocol	tag_protocol;

	/*
	 * The switch and port to which the CPU is attached.
	 */
	s8			cpu_switch;
	s8			cpu_port;

	/*
	 * Link state polling.
	 */
	int			link_poll_needed;
	struct work_struct	link_poll_work;
	struct timer_list	link_poll_timer;

	/*
	 * Data for the individual switch chips.
	 */
	struct dsa_switch	*ds[DSA_MAX_SWITCHES];
};

struct dsa_switch {
	/*
	 * Parent switch tree, and switch index.
	 */
	struct dsa_switch_tree	*dst;
	int			index;

	/*
	 * Tagging protocol understood by this switch
	 */
	enum dsa_tag_protocol	tag_protocol;

	/*
	 * Configuration data for this switch.
	 */
	struct dsa_chip_data	*pd;

	/*
	 * The used switch driver.
	 */
	struct dsa_switch_driver	*drv;

	/*
	 * Reference to host device to use.
	 */
	struct device		*master_dev;

#ifdef CONFIG_NET_DSA_HWMON
	/*
	 * Hardware monitoring information
	 */
	char			hwmon_name[IFNAMSIZ + 8];
	struct device		*hwmon_dev;
#endif

	/*
	 * Slave mii_bus and devices for the individual ports.
	 */
	u32			dsa_port_mask;
	u32			phys_port_mask;
	u32			phys_mii_mask;
	struct mii_bus		*slave_mii_bus;
	struct net_device	*ports[DSA_MAX_PORTS];
};

static inline bool dsa_is_cpu_port(struct dsa_switch *ds, int p)
{
	return !!(ds->index == ds->dst->cpu_switch && p == ds->dst->cpu_port);
}

static inline bool dsa_is_dsa_port(struct dsa_switch *ds, int p)
{
	return !!((ds->dsa_port_mask) & (1 << p));
}

static inline bool dsa_is_port_initialized(struct dsa_switch *ds, int p)
{
	return ds->phys_port_mask & (1 << p) && ds->ports[p];
}

static inline u8 dsa_upstream_port(struct dsa_switch *ds)
{
	struct dsa_switch_tree *dst = ds->dst;

	/*
	 * If this is the root switch (i.e. the switch that connects
	 * to the CPU), return the cpu port number on this switch.
	 * Else return the (DSA) port number that connects to the
	 * switch that is one hop closer to the cpu.
	 */
	if (dst->cpu_switch == ds->index)
		return dst->cpu_port;
	else
		return ds->pd->rtable[dst->cpu_switch];
}

struct switchdev_trans;
struct switchdev_obj;
struct switchdev_obj_port_fdb;

struct dsa_switch_driver {
	struct list_head	list;

	enum dsa_tag_protocol	tag_protocol;
	int			priv_size;

	/*
	 * Probing and setup.
	 */
	char	*(*probe)(struct device *host_dev, int sw_addr);
	int	(*setup)(struct dsa_switch *ds);
	int	(*set_addr)(struct dsa_switch *ds, u8 *addr);
	u32	(*get_phy_flags)(struct dsa_switch *ds, int port);

	/*
	 * Access to the switch's PHY registers.
	 */
	int	(*phy_read)(struct dsa_switch *ds, int port, int regnum);
	int	(*phy_write)(struct dsa_switch *ds, int port,
			     int regnum, u16 val);

	/*
	 * Link state polling and IRQ handling.
	 */
	void	(*poll_link)(struct dsa_switch *ds);

	/*
	 * Link state adjustment (called from libphy)
	 */
	void	(*adjust_link)(struct dsa_switch *ds, int port,
				struct phy_device *phydev);
	void	(*fixed_link_update)(struct dsa_switch *ds, int port,
				struct fixed_phy_status *st);

	/*
	 * ethtool hardware statistics.
	 */
	void	(*get_strings)(struct dsa_switch *ds, int port, uint8_t *data);
	void	(*get_ethtool_stats)(struct dsa_switch *ds,
				     int port, uint64_t *data);
	int	(*get_sset_count)(struct dsa_switch *ds);

	/*
	 * ethtool Wake-on-LAN
	 */
	void	(*get_wol)(struct dsa_switch *ds, int port,
			   struct ethtool_wolinfo *w);
	int	(*set_wol)(struct dsa_switch *ds, int port,
			   struct ethtool_wolinfo *w);

	/*
	 * Suspend and resume
	 */
	int	(*suspend)(struct dsa_switch *ds);
	int	(*resume)(struct dsa_switch *ds);

	/*
	 * Port enable/disable
	 */
	int	(*port_enable)(struct dsa_switch *ds, int port,
			       struct phy_device *phy);
	void	(*port_disable)(struct dsa_switch *ds, int port,
				struct phy_device *phy);

	/*
	 * EEE setttings
	 */
	int	(*set_eee)(struct dsa_switch *ds, int port,
			   struct phy_device *phydev,
			   struct ethtool_eee *e);
	int	(*get_eee)(struct dsa_switch *ds, int port,
			   struct ethtool_eee *e);

#ifdef CONFIG_NET_DSA_HWMON
	/* Hardware monitoring */
	int	(*get_temp)(struct dsa_switch *ds, int *temp);
	int	(*get_temp_limit)(struct dsa_switch *ds, int *temp);
	int	(*set_temp_limit)(struct dsa_switch *ds, int temp);
	int	(*get_temp_alarm)(struct dsa_switch *ds, bool *alarm);
#endif

	/* EEPROM access */
	int	(*get_eeprom_len)(struct dsa_switch *ds);
	int	(*get_eeprom)(struct dsa_switch *ds,
			      struct ethtool_eeprom *eeprom, u8 *data);
	int	(*set_eeprom)(struct dsa_switch *ds,
			      struct ethtool_eeprom *eeprom, u8 *data);

	/*
	 * Register access.
	 */
	int	(*get_regs_len)(struct dsa_switch *ds, int port);
	void	(*get_regs)(struct dsa_switch *ds, int port,
			    struct ethtool_regs *regs, void *p);

	/*
	 * Bridge integration
	 */
	int	(*port_join_bridge)(struct dsa_switch *ds, int port,
				    u32 br_port_mask);
	int	(*port_leave_bridge)(struct dsa_switch *ds, int port,
				     u32 br_port_mask);
	int	(*port_stp_update)(struct dsa_switch *ds, int port,
				   u8 state);

	/*
	 * VLAN support
	 */
	int	(*port_pvid_get)(struct dsa_switch *ds, int port, u16 *pvid);
	int	(*port_pvid_set)(struct dsa_switch *ds, int port, u16 pvid);
	int	(*port_vlan_add)(struct dsa_switch *ds, int port, u16 vid,
				 bool untagged);
	int	(*port_vlan_del)(struct dsa_switch *ds, int port, u16 vid);
	int	(*vlan_getnext)(struct dsa_switch *ds, u16 *vid,
				unsigned long *ports, unsigned long *untagged);

	/*
	 * Forwarding database
	 */
	int	(*port_fdb_prepare)(struct dsa_switch *ds, int port,
				    const struct switchdev_obj_port_fdb *fdb,
				    struct switchdev_trans *trans);
	int	(*port_fdb_add)(struct dsa_switch *ds, int port,
				const struct switchdev_obj_port_fdb *fdb,
				struct switchdev_trans *trans);
	int	(*port_fdb_del)(struct dsa_switch *ds, int port,
				const struct switchdev_obj_port_fdb *fdb);
	int	(*port_fdb_dump)(struct dsa_switch *ds, int port,
				 struct switchdev_obj_port_fdb *fdb,
				 int (*cb)(struct switchdev_obj *obj));
};

void register_switch_driver(struct dsa_switch_driver *type);
void unregister_switch_driver(struct dsa_switch_driver *type);
struct mii_bus *dsa_host_dev_to_mii_bus(struct device *dev);

static inline void *ds_to_priv(struct dsa_switch *ds)
{
	return (void *)(ds + 1);
}

static inline bool dsa_uses_tagged_protocol(struct dsa_switch_tree *dst)
{
	return dst->rcv != NULL;
}
#endif
Commit	Line	Data
91da11f8 LB	1	/*
91da11f8 LB	2	* include/net/dsa.h - Driver for Distributed Switch Architecture switch chips
e84665c9	3	* Copyright (c) 2008-2009 Marvell Semiconductor
91da11f8 LB	4	*
	5	* This program is free software; you can redistribute it and/or modify
	6	* it under the terms of the GNU General Public License as published by
	7	* the Free Software Foundation; either version 2 of the License, or
	8	* (at your option) any later version.
	9	*/
	10
	11	#ifndef __LINUX_NET_DSA_H
	12	#define __LINUX_NET_DSA_H
	13
ea1f51be	14	#include <linux/if_ether.h>
c8f0b869	15	#include <linux/list.h>
cf50dcc2 BH	16	#include <linux/timer.h>
cf50dcc2 BH	17	#include <linux/workqueue.h>
fa981d9a	18	#include <linux/of.h>
ec9436ba	19	#include <linux/phy.h>
ce31b31c	20	#include <linux/phy_fixed.h>
a2820543	21	#include <linux/ethtool.h>
cf50dcc2	22
ac7a04c3 FF	23	enum dsa_tag_protocol {
	24	DSA_TAG_PROTO_NONE = 0,
	25	DSA_TAG_PROTO_DSA,
	26	DSA_TAG_PROTO_TRAILER,
	27	DSA_TAG_PROTO_EDSA,
	28	DSA_TAG_PROTO_BRCM,
	29	};
5037d532	30
e84665c9 LB	31	#define DSA_MAX_SWITCHES 4
	32	#define DSA_MAX_PORTS 12
	33
	34	struct dsa_chip_data {
	35	/*
	36	* How to access the switch configuration registers.
	37	*/
b4d2394d	38	struct device *host_dev;
e84665c9 LB	39	int sw_addr;
e84665c9 LB	40
6793abb4 GR	41	/* set to size of eeprom if supported by the switch */
	42	int eeprom_len;
	43
fa981d9a FF	44	/* Device tree node pointer for this specific switch chip
	45	* used during switch setup in case additional properties
	46	* and resources needs to be used
	47	*/
	48	struct device_node *of_node;
	49
e84665c9 LB	50	/*
	51	* The names of the switch's ports. Use "cpu" to
	52	* designate the switch port that the cpu is connected to,
	53	* "dsa" to indicate that this port is a DSA link to
	54	* another switch, NULL to indicate the port is unused,
	55	* or any other string to indicate this is a physical port.
	56	*/
	57	char *port_names[DSA_MAX_PORTS];
bd47497a	58	struct device_node *port_dn[DSA_MAX_PORTS];
e84665c9 LB	59
	60	/*
	61	* An array (with nr_chips elements) of which element [a]
	62	* indicates which port on this switch should be used to
	63	* send packets to that are destined for switch a. Can be
	64	* NULL if there is only one switch chip.
	65	*/
	66	s8 *rtable;
	67	};
91da11f8 LB	68
	69	struct dsa_platform_data {
	70	/*
	71	* Reference to a Linux network interface that connects
e84665c9	72	* to the root switch chip of the tree.
91da11f8 LB	73	*/
91da11f8 LB	74	struct device *netdev;
769a0202	75	struct net_device *of_netdev;
91da11f8 LB	76
91da11f8 LB	77	/*
e84665c9 LB	78	* Info structs describing each of the switch chips
e84665c9 LB	79	* connected via this network interface.
91da11f8	80	*/
e84665c9 LB	81	int nr_chips;
e84665c9 LB	82	struct dsa_chip_data *chip;
91da11f8 LB	83	};
91da11f8 LB	84
5075314e	85	struct packet_type;
3e8a72d1	86
cf50dcc2 BH	87	struct dsa_switch_tree {
	88	/*
	89	* Configuration data for the platform device that owns
	90	* this dsa switch tree instance.
	91	*/
	92	struct dsa_platform_data *pd;
	93
	94	/*
	95	* Reference to network device to use, and which tagging
	96	* protocol to use.
	97	*/
	98	struct net_device *master_netdev;
5075314e AD	99	int (rcv)(struct sk_buff skb,
	100	struct net_device *dev,
	101	struct packet_type *pt,
	102	struct net_device *orig_dev);
ac7a04c3	103	enum dsa_tag_protocol tag_protocol;
cf50dcc2 BH	104
	105	/*
	106	* The switch and port to which the CPU is attached.
	107	*/
	108	s8 cpu_switch;
	109	s8 cpu_port;
	110
	111	/*
	112	* Link state polling.
	113	*/
	114	int link_poll_needed;
	115	struct work_struct link_poll_work;
	116	struct timer_list link_poll_timer;
	117
	118	/*
	119	* Data for the individual switch chips.
	120	*/
	121	struct dsa_switch *ds[DSA_MAX_SWITCHES];
	122	};
	123
c8f0b869 BH	124	struct dsa_switch {
	125	/*
	126	* Parent switch tree, and switch index.
	127	*/
	128	struct dsa_switch_tree *dst;
	129	int index;
	130
59299031 FF	131	/*
	132	* Tagging protocol understood by this switch
	133	*/
	134	enum dsa_tag_protocol tag_protocol;
	135
c8f0b869 BH	136	/*
	137	* Configuration data for this switch.
	138	*/
	139	struct dsa_chip_data *pd;
	140
	141	/*
	142	* The used switch driver.
	143	*/
	144	struct dsa_switch_driver *drv;
	145
	146	/*
b4d2394d	147	* Reference to host device to use.
c8f0b869	148	*/
b4d2394d	149	struct device *master_dev;
c8f0b869	150
51579c3f GR	151	#ifdef CONFIG_NET_DSA_HWMON
	152	/*
	153	* Hardware monitoring information
	154	*/
	155	char hwmon_name[IFNAMSIZ + 8];
	156	struct device *hwmon_dev;
	157	#endif
	158
c8f0b869 BH	159	/*
	160	* Slave mii_bus and devices for the individual ports.
	161	*/
	162	u32 dsa_port_mask;
	163	u32 phys_port_mask;
0d8bcdd3	164	u32 phys_mii_mask;
c8f0b869 BH	165	struct mii_bus *slave_mii_bus;
	166	struct net_device *ports[DSA_MAX_PORTS];
	167	};
	168
	169	static inline bool dsa_is_cpu_port(struct dsa_switch *ds, int p)
	170	{
	171	return !!(ds->index == ds->dst->cpu_switch && p == ds->dst->cpu_port);
	172	}
	173
60045cbf AL	174	static inline bool dsa_is_dsa_port(struct dsa_switch *ds, int p)
	175	{
	176	return !!((ds->dsa_port_mask) & (1 << p));
	177	}
	178
d79d2107 GR	179	static inline bool dsa_is_port_initialized(struct dsa_switch *ds, int p)
	180	{
	181	return ds->phys_port_mask & (1 << p) && ds->ports[p];
	182	}
	183
c8f0b869 BH	184	static inline u8 dsa_upstream_port(struct dsa_switch *ds)
	185	{
	186	struct dsa_switch_tree *dst = ds->dst;
	187
	188	/*
	189	* If this is the root switch (i.e. the switch that connects
	190	* to the CPU), return the cpu port number on this switch.
	191	* Else return the (DSA) port number that connects to the
	192	* switch that is one hop closer to the cpu.
	193	*/
	194	if (dst->cpu_switch == ds->index)
	195	return dst->cpu_port;
	196	else
	197	return ds->pd->rtable[dst->cpu_switch];
	198	}
	199
146a3206	200	struct switchdev_trans;
ea70ba98	201	struct switchdev_obj;
146a3206 VD	202	struct switchdev_obj_port_fdb;
146a3206 VD	203
c8f0b869 BH	204	struct dsa_switch_driver {
	205	struct list_head list;
	206
ac7a04c3	207	enum dsa_tag_protocol tag_protocol;
c8f0b869 BH	208	int priv_size;
	209
	210	/*
	211	* Probing and setup.
	212	*/
b4d2394d	213	char (probe)(struct device *host_dev, int sw_addr);
c8f0b869 BH	214	int (setup)(struct dsa_switch ds);
c8f0b869 BH	215	int (set_addr)(struct dsa_switch ds, u8 *addr);
6819563e	216	u32 (get_phy_flags)(struct dsa_switch ds, int port);
c8f0b869 BH	217
	218	/*
	219	* Access to the switch's PHY registers.
	220	*/
	221	int (phy_read)(struct dsa_switch ds, int port, int regnum);
	222	int (phy_write)(struct dsa_switch ds, int port,
	223	int regnum, u16 val);
	224
	225	/*
	226	* Link state polling and IRQ handling.
	227	*/
	228	void (poll_link)(struct dsa_switch ds);
	229
ec9436ba FF	230	/*
	231	* Link state adjustment (called from libphy)
	232	*/
	233	void (adjust_link)(struct dsa_switch ds, int port,
	234	struct phy_device *phydev);
ce31b31c FF	235	void (fixed_link_update)(struct dsa_switch ds, int port,
ce31b31c FF	236	struct fixed_phy_status *st);
ec9436ba	237
c8f0b869 BH	238	/*
	239	* ethtool hardware statistics.
	240	*/
	241	void (get_strings)(struct dsa_switch ds, int port, uint8_t *data);
	242	void (get_ethtool_stats)(struct dsa_switch ds,
	243	int port, uint64_t *data);
	244	int (get_sset_count)(struct dsa_switch ds);
24462549	245
19e57c4e FF	246	/*
	247	* ethtool Wake-on-LAN
	248	*/
	249	void (get_wol)(struct dsa_switch ds, int port,
	250	struct ethtool_wolinfo *w);
	251	int (set_wol)(struct dsa_switch ds, int port,
	252	struct ethtool_wolinfo *w);
	253
24462549 FF	254	/*
	255	* Suspend and resume
	256	*/
	257	int (suspend)(struct dsa_switch ds);
	258	int (resume)(struct dsa_switch ds);
b2f2af21 FF	259
	260	/*
	261	* Port enable/disable
	262	*/
	263	int (port_enable)(struct dsa_switch ds, int port,
	264	struct phy_device *phy);
	265	void (port_disable)(struct dsa_switch ds, int port,
	266	struct phy_device *phy);
7905288f FF	267
	268	/*
	269	* EEE setttings
	270	*/
	271	int (set_eee)(struct dsa_switch ds, int port,
	272	struct phy_device *phydev,
	273	struct ethtool_eee *e);
	274	int (get_eee)(struct dsa_switch ds, int port,
	275	struct ethtool_eee *e);
51579c3f GR	276
	277	#ifdef CONFIG_NET_DSA_HWMON
	278	/* Hardware monitoring */
	279	int (get_temp)(struct dsa_switch ds, int *temp);
	280	int (get_temp_limit)(struct dsa_switch ds, int *temp);
	281	int (set_temp_limit)(struct dsa_switch ds, int temp);
	282	int (get_temp_alarm)(struct dsa_switch ds, bool *alarm);
	283	#endif
6793abb4 GR	284
	285	/* EEPROM access */
	286	int (get_eeprom_len)(struct dsa_switch ds);
	287	int (get_eeprom)(struct dsa_switch ds,
	288	struct ethtool_eeprom eeprom, u8 data);
	289	int (set_eeprom)(struct dsa_switch ds,
	290	struct ethtool_eeprom eeprom, u8 data);
3d762a0f GR	291
	292	/*
	293	* Register access.
	294	*/
	295	int (get_regs_len)(struct dsa_switch ds, int port);
	296	void (get_regs)(struct dsa_switch ds, int port,
	297	struct ethtool_regs regs, void p);
b73adef6 FF	298
	299	/*
	300	* Bridge integration
	301	*/
	302	int (port_join_bridge)(struct dsa_switch ds, int port,
	303	u32 br_port_mask);
	304	int (port_leave_bridge)(struct dsa_switch ds, int port,
	305	u32 br_port_mask);
	306	int (port_stp_update)(struct dsa_switch ds, int port,
	307	u8 state);
2a778e1b	308
11149536 VD	309	/*
	310	* VLAN support
	311	*/
	312	int (port_pvid_get)(struct dsa_switch ds, int port, u16 *pvid);
	313	int (port_pvid_set)(struct dsa_switch ds, int port, u16 pvid);
	314	int (port_vlan_add)(struct dsa_switch ds, int port, u16 vid,
	315	bool untagged);
	316	int (port_vlan_del)(struct dsa_switch ds, int port, u16 vid);
	317	int (vlan_getnext)(struct dsa_switch ds, u16 *vid,
	318	unsigned long ports, unsigned long untagged);
	319
2a778e1b VD	320	/*
	321	* Forwarding database
	322	*/
146a3206 VD	323	int (port_fdb_prepare)(struct dsa_switch ds, int port,
	324	const struct switchdev_obj_port_fdb *fdb,
	325	struct switchdev_trans *trans);
2a778e1b	326	int (port_fdb_add)(struct dsa_switch ds, int port,
1f36faf2 VD	327	const struct switchdev_obj_port_fdb *fdb,
1f36faf2 VD	328	struct switchdev_trans *trans);
2a778e1b	329	int (port_fdb_del)(struct dsa_switch ds, int port,
8057b3e7	330	const struct switchdev_obj_port_fdb *fdb);
ea70ba98 VD	331	int (port_fdb_dump)(struct dsa_switch ds, int port,
	332	struct switchdev_obj_port_fdb *fdb,
	333	int (cb)(struct switchdev_obj obj));
c8f0b869 BH	334	};
	335
	336	void register_switch_driver(struct dsa_switch_driver *type);
	337	void unregister_switch_driver(struct dsa_switch_driver *type);
b4d2394d	338	struct mii_bus dsa_host_dev_to_mii_bus(struct device dev);
c8f0b869	339
7fa857ed FF	340	static inline void ds_to_priv(struct dsa_switch ds)
	341	{
	342	return (void *)(ds + 1);
	343	}
	344
5aed85ce FF	345	static inline bool dsa_uses_tagged_protocol(struct dsa_switch_tree *dst)
5aed85ce FF	346	{
5075314e	347	return dst->rcv != NULL;
5aed85ce	348	}
91da11f8	349	#endif