blob: 7c0665faa8e12572acd10f2a3063f6cd9c8ab28a [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0+
#include <asm/io.h>
#include <cpu_func.h>
#include <dm.h>
#include <malloc.h>
#include <net.h>
#include <netdev.h>
#include <pci.h>
#include <linux/bitops.h>
#include <linux/delay.h>
#define SROM_DLEVEL 0
/* PCI Registers. */
#define PCI_CFDA_PSM 0x43
#define CFRV_RN 0x000000f0 /* Revision Number */
#define WAKEUP 0x00 /* Power Saving Wakeup */
#define SLEEP 0x80 /* Power Saving Sleep Mode */
#define DC2114x_BRK 0x0020 /* CFRV break between DC21142 & DC21143 */
/* Ethernet chip registers. */
#define DE4X5_BMR 0x000 /* Bus Mode Register */
#define DE4X5_TPD 0x008 /* Transmit Poll Demand Reg */
#define DE4X5_RRBA 0x018 /* RX Ring Base Address Reg */
#define DE4X5_TRBA 0x020 /* TX Ring Base Address Reg */
#define DE4X5_STS 0x028 /* Status Register */
#define DE4X5_OMR 0x030 /* Operation Mode Register */
#define DE4X5_SICR 0x068 /* SIA Connectivity Register */
#define DE4X5_APROM 0x048 /* Ethernet Address PROM */
/* Register bits. */
#define BMR_SWR 0x00000001 /* Software Reset */
#define STS_TS 0x00700000 /* Transmit Process State */
#define STS_RS 0x000e0000 /* Receive Process State */
#define OMR_ST 0x00002000 /* Start/Stop Transmission Command */
#define OMR_SR 0x00000002 /* Start/Stop Receive */
#define OMR_PS 0x00040000 /* Port Select */
#define OMR_SDP 0x02000000 /* SD Polarity - MUST BE ASSERTED */
#define OMR_PM 0x00000080 /* Pass All Multicast */
/* Descriptor bits. */
#define R_OWN 0x80000000 /* Own Bit */
#define RD_RER 0x02000000 /* Receive End Of Ring */
#define RD_LS 0x00000100 /* Last Descriptor */
#define RD_ES 0x00008000 /* Error Summary */
#define TD_TER 0x02000000 /* Transmit End Of Ring */
#define T_OWN 0x80000000 /* Own Bit */
#define TD_LS 0x40000000 /* Last Segment */
#define TD_FS 0x20000000 /* First Segment */
#define TD_ES 0x00008000 /* Error Summary */
#define TD_SET 0x08000000 /* Setup Packet */
/* The EEPROM commands include the alway-set leading bit. */
#define SROM_WRITE_CMD 5
#define SROM_READ_CMD 6
#define SROM_ERASE_CMD 7
#define SROM_HWADD 0x0014 /* Hardware Address offset in SROM */
#define SROM_RD 0x00004000 /* Read from Boot ROM */
#define EE_DATA_WRITE 0x04 /* EEPROM chip data in. */
#define EE_WRITE_0 0x4801
#define EE_WRITE_1 0x4805
#define EE_DATA_READ 0x08 /* EEPROM chip data out. */
#define SROM_SR 0x00000800 /* Select Serial ROM when set */
#define DT_IN 0x00000004 /* Serial Data In */
#define DT_CLK 0x00000002 /* Serial ROM Clock */
#define DT_CS 0x00000001 /* Serial ROM Chip Select */
#define POLL_DEMAND 1
#if CONFIG_IS_ENABLED(TULIP_SUPPORT_NON_PCI)
#define phys_to_bus(dev, a) virt_to_phys((volatile const void *)(a))
#else
#define phys_to_bus(dev, a) dm_pci_phys_to_mem((dev), (a))
#endif
/* Number of TX descriptors */
#if CONFIG_IS_ENABLED(TULIP_MULTIPLE_TX_DESC)
#define NUM_TX_DESC 4
#else
#define NUM_TX_DESC 1
#endif
#define NUM_RX_DESC PKTBUFSRX
#define RX_BUFF_SZ PKTSIZE_ALIGN
#define TOUT_LOOP 1000000
#define SETUP_FRAME_LEN 192
struct de4x5_desc {
volatile s32 status;
u32 des1;
u32 buf;
u32 next;
};
/* Assigned for network card's ring buffer:
* Some CPU might treat these memories as cached, and changes to these memories
* won't immediately be visible to each other. It is necessary to ensure that
* these memories between the CPU and the network card are marked as uncached.
*/
static struct de4x5_desc rx_ring[NUM_RX_DESC] __aligned(32);
static struct de4x5_desc tx_ring[NUM_TX_DESC] __aligned(32);
struct dc2114x_priv {
struct de4x5_desc *rx_ring; /* Must be uncached to CPU */
struct de4x5_desc *tx_ring; /* Must be uncached to CPU */
int rx_new; /* RX descriptor ring pointer */
int tx_new; /* TX descriptor ring pointer */
char rx_ring_size;
char tx_ring_size;
struct udevice *devno;
char *name;
void __iomem *iobase;
u8 *enetaddr;
};
/* RX and TX descriptor ring */
static u32 dc2114x_inl(struct dc2114x_priv *priv, u32 addr)
{
return le32_to_cpu(readl(priv->iobase + addr));
}
static void dc2114x_outl(struct dc2114x_priv *priv, u32 command, u32 addr)
{
writel(cpu_to_le32(command), priv->iobase + addr);
}
static void reset_de4x5(struct dc2114x_priv *priv)
{
u32 i;
i = dc2114x_inl(priv, DE4X5_BMR);
mdelay(1);
dc2114x_outl(priv, i | BMR_SWR, DE4X5_BMR);
mdelay(1);
dc2114x_outl(priv, i, DE4X5_BMR);
mdelay(1);
for (i = 0; i < 5; i++) {
dc2114x_inl(priv, DE4X5_BMR);
mdelay(10);
}
mdelay(1);
}
static void start_de4x5(struct dc2114x_priv *priv)
{
u32 omr;
omr = dc2114x_inl(priv, DE4X5_OMR);
omr |= OMR_ST | OMR_SR;
dc2114x_outl(priv, omr, DE4X5_OMR); /* Enable the TX and/or RX */
}
static void stop_de4x5(struct dc2114x_priv *priv)
{
u32 omr;
omr = dc2114x_inl(priv, DE4X5_OMR);
omr &= ~(OMR_ST | OMR_SR);
dc2114x_outl(priv, omr, DE4X5_OMR); /* Disable the TX and/or RX */
}
/* SROM Read and write routines. */
static void sendto_srom(struct dc2114x_priv *priv, u_int command, u_long addr)
{
dc2114x_outl(priv, command, addr);
udelay(1);
}
static int getfrom_srom(struct dc2114x_priv *priv, u_long addr)
{
u32 tmp = dc2114x_inl(priv, addr);
udelay(1);
return tmp;
}
/* Note: this routine returns extra data bits for size detection. */
static int do_read_eeprom(struct dc2114x_priv *priv, u_long ioaddr, int location,
int addr_len)
{
int read_cmd = location | (SROM_READ_CMD << addr_len);
unsigned int retval = 0;
int i;
sendto_srom(priv, SROM_RD | SROM_SR, ioaddr);
sendto_srom(priv, SROM_RD | SROM_SR | DT_CS, ioaddr);
debug_cond(SROM_DLEVEL >= 1, " EEPROM read at %d ", location);
/* Shift the read command bits out. */
for (i = 4 + addr_len; i >= 0; i--) {
short dataval = (read_cmd & (1 << i)) ? EE_DATA_WRITE : 0;
sendto_srom(priv, SROM_RD | SROM_SR | DT_CS | dataval,
ioaddr);
udelay(10);
sendto_srom(priv, SROM_RD | SROM_SR | DT_CS | dataval | DT_CLK,
ioaddr);
udelay(10);
debug_cond(SROM_DLEVEL >= 2, "%X",
getfrom_srom(priv, ioaddr) & 15);
retval = (retval << 1) |
!!(getfrom_srom(priv, ioaddr) & EE_DATA_READ);
}
sendto_srom(priv, SROM_RD | SROM_SR | DT_CS, ioaddr);
debug_cond(SROM_DLEVEL >= 2, " :%X:", getfrom_srom(priv, ioaddr) & 15);
for (i = 16; i > 0; i--) {
sendto_srom(priv, SROM_RD | SROM_SR | DT_CS | DT_CLK, ioaddr);
udelay(10);
debug_cond(SROM_DLEVEL >= 2, "%X",
getfrom_srom(priv, ioaddr) & 15);
retval = (retval << 1) |
!!(getfrom_srom(priv, ioaddr) & EE_DATA_READ);
sendto_srom(priv, SROM_RD | SROM_SR | DT_CS, ioaddr);
udelay(10);
}
/* Terminate the EEPROM access. */
sendto_srom(priv, SROM_RD | SROM_SR, ioaddr);
debug_cond(SROM_DLEVEL >= 2, " EEPROM value at %d is %5.5x.\n",
location, retval);
return retval;
}
/*
* This executes a generic EEPROM command, typically a write or write
* enable. It returns the data output from the EEPROM, and thus may
* also be used for reads.
*/
static int do_eeprom_cmd(struct dc2114x_priv *priv, u_long ioaddr, int cmd,
int cmd_len)
{
unsigned int retval = 0;
debug_cond(SROM_DLEVEL >= 1, " EEPROM op 0x%x: ", cmd);
sendto_srom(priv, SROM_RD | SROM_SR | DT_CS | DT_CLK, ioaddr);
/* Shift the command bits out. */
do {
short dataval = (cmd & BIT(cmd_len)) ? EE_WRITE_1 : EE_WRITE_0;
sendto_srom(priv, dataval, ioaddr);
udelay(10);
debug_cond(SROM_DLEVEL >= 2, "%X",
getfrom_srom(priv, ioaddr) & 15);
sendto_srom(priv, dataval | DT_CLK, ioaddr);
udelay(10);
retval = (retval << 1) |
!!(getfrom_srom(priv, ioaddr) & EE_DATA_READ);
} while (--cmd_len >= 0);
sendto_srom(priv, SROM_RD | SROM_SR | DT_CS, ioaddr);
/* Terminate the EEPROM access. */
sendto_srom(priv, SROM_RD | SROM_SR, ioaddr);
debug_cond(SROM_DLEVEL >= 1, " EEPROM result is 0x%5.5x.\n", retval);
return retval;
}
static int read_srom(struct dc2114x_priv *priv, u_long ioaddr, int index)
{
int ee_addr_size;
ee_addr_size = (do_read_eeprom(priv, ioaddr, 0xff, 8) & BIT(18)) ? 8 : 6;
return do_eeprom_cmd(priv, ioaddr, 0xffff |
(((SROM_READ_CMD << ee_addr_size) | index) << 16),
3 + ee_addr_size + 16);
}
static void send_setup_frame(struct dc2114x_priv *priv)
{
/* We are writing setup frame and these changes should be visible to the
* network card immediately. So let's directly read/write through the
* uncached window.
*/
char __setup_frame[SETUP_FRAME_LEN] __aligned(32);
char *setup_frame = (char *)map_physmem((phys_addr_t)virt_to_phys(__setup_frame), 0, MAP_NOCACHE);
char *pa = &setup_frame[0];
int i;
memset(pa, 0xff, SETUP_FRAME_LEN);
for (i = 0; i < ETH_ALEN; i++) {
*(pa + (i & 1)) = priv->enetaddr[i];
if (i & 0x01)
pa += 4;
}
for (i = 0; priv->tx_ring[priv->tx_new].status & cpu_to_le32(T_OWN); i++) {
if (i < TOUT_LOOP)
continue;
printf("%s: tx error buffer not ready\n", priv->name);
return;
}
priv->tx_ring[priv->tx_new].buf = cpu_to_le32(phys_to_bus(priv->devno,
(phys_addr_t)&setup_frame[0]));
#if CONFIG_IS_ENABLED(TULIP_MULTIPLE_TX_DESC)
priv->tx_ring[priv->tx_new].des1 = cpu_to_le32(TD_SET | SETUP_FRAME_LEN);
priv->tx_ring[priv->tx_ring_size - 1].des1 |= cpu_to_le32(TD_TER);
#else
priv->tx_ring[priv->tx_new].des1 = cpu_to_le32(TD_TER | TD_SET | SETUP_FRAME_LEN);
#endif
priv->tx_ring[priv->tx_new].status = cpu_to_le32(T_OWN);
dc2114x_outl(priv, POLL_DEMAND, DE4X5_TPD);
for (i = 0; priv->tx_ring[priv->tx_new].status & cpu_to_le32(T_OWN); i++) {
if (i < TOUT_LOOP)
continue;
printf("%s: tx buffer not ready\n", priv->name);
return;
}
if (le32_to_cpu(priv->tx_ring[priv->tx_new].status) != 0x7FFFFFFF) {
debug("TX error status2 = 0x%08X\n",
le32_to_cpu(priv->tx_ring[priv->tx_new].status));
}
priv->tx_new = (priv->tx_new + 1) % NUM_TX_DESC;
}
static int dc21x4x_send_common(struct dc2114x_priv *priv, void *packet, int length)
{
int status = -1;
int i;
if (length <= 0) {
printf("%s: bad packet size: %d\n", priv->name, length);
goto done;
}
for (i = 0; priv->tx_ring[priv->tx_new].status & cpu_to_le32(T_OWN); i++) {
if (i < TOUT_LOOP)
continue;
printf("%s: tx error buffer not ready\n", priv->name);
goto done;
}
/* Packet should be visible to the network card */
flush_dcache_range((phys_addr_t)packet, (phys_addr_t)(packet + RX_BUFF_SZ));
priv->tx_ring[priv->tx_new].buf = cpu_to_le32(phys_to_bus(priv->devno,
(phys_addr_t)packet));
#if CONFIG_IS_ENABLED(TULIP_MULTIPLE_TX_DESC)
priv->tx_ring[priv->tx_new].des1 = cpu_to_le32(TD_LS | TD_FS | length);
priv->tx_ring[priv->tx_ring_size - 1].des1 |= cpu_to_le32(TD_TER);
#else
priv->tx_ring[priv->tx_new].des1 = cpu_to_le32(TD_TER | TD_LS | TD_FS | length);
#endif
priv->tx_ring[priv->tx_new].status = cpu_to_le32(T_OWN);
dc2114x_outl(priv, POLL_DEMAND, DE4X5_TPD);
for (i = 0; priv->tx_ring[priv->tx_new].status & cpu_to_le32(T_OWN); i++) {
if (i < TOUT_LOOP)
continue;
printf(".%s: tx buffer not ready\n", priv->name);
goto done;
}
if (le32_to_cpu(priv->tx_ring[priv->tx_new].status) & TD_ES) {
priv->tx_ring[priv->tx_new].status = 0x0;
#if !CONFIG_IS_ENABLED(TULIP_IGNORE_TX_NO_CARRIER)
goto done;
#endif
}
status = length;
done:
priv->tx_new = (priv->tx_new + 1) % NUM_TX_DESC;
return status;
}
static int dc21x4x_recv_check(struct dc2114x_priv *priv)
{
int length = 0;
u32 status;
status = le32_to_cpu(priv->rx_ring[priv->rx_new].status);
if (status & R_OWN)
return 0;
if (status & RD_LS) {
/* Valid frame status. */
if (status & RD_ES) {
/* There was an error. */
printf("RX error status = 0x%08X\n", status);
return -EINVAL;
} else {
/* A valid frame received. */
length = (le32_to_cpu(priv->rx_ring[priv->rx_new].status)
>> 16);
return length;
}
}
return -EAGAIN;
}
static int dc21x4x_init_common(struct dc2114x_priv *priv)
{
int i;
reset_de4x5(priv);
if (dc2114x_inl(priv, DE4X5_STS) & (STS_TS | STS_RS)) {
printf("Error: Cannot reset ethernet controller.\n");
return -1;
}
/* 2024-07:
* Remove the OMR_PM flag and choose 16 perfect filtering mode since in
* modern networks there're plenty of multicasts and set ORM_PM flag will
* increase the dc2114x's workload and ask the U-Boot to handle packets
* not related to itself. And most of the time, U-Boot does not need this
* feature.
*
* A better way: let user to decide whether to have this flag.
*/
dc2114x_outl(priv, OMR_SDP | OMR_PS, DE4X5_OMR);
for (i = 0; i < NUM_RX_DESC; i++) {
priv->rx_ring[i].status = cpu_to_le32(R_OWN);
priv->rx_ring[i].des1 = cpu_to_le32(RX_BUFF_SZ);
priv->rx_ring[i].buf = cpu_to_le32(phys_to_bus(priv->devno,
(phys_addr_t)net_rx_packets[i]));
priv->rx_ring[i].next = 0;
}
for (i = 0; i < NUM_TX_DESC; i++) {
priv->tx_ring[i].status = 0;
priv->tx_ring[i].des1 = 0;
priv->tx_ring[i].buf = 0;
priv->tx_ring[i].next = 0;
}
priv->rx_ring_size = NUM_RX_DESC;
priv->tx_ring_size = NUM_TX_DESC;
/* Write the end of list marker to the descriptor lists. */
priv->rx_ring[priv->rx_ring_size - 1].des1 |= cpu_to_le32(RD_RER);
priv->tx_ring[priv->tx_ring_size - 1].des1 |= cpu_to_le32(TD_TER);
/* Tell the adapter where the TX/RX rings are located. */
dc2114x_outl(priv, phys_to_bus(priv->devno, (phys_addr_t)priv->rx_ring),
DE4X5_RRBA);
dc2114x_outl(priv, phys_to_bus(priv->devno, (phys_addr_t)priv->tx_ring),
DE4X5_TRBA);
start_de4x5(priv);
priv->tx_new = 0;
priv->rx_new = 0;
send_setup_frame(priv);
return 0;
}
static void dc21x4x_halt_common(struct dc2114x_priv *priv)
{
stop_de4x5(priv);
dc2114x_outl(priv, 0, DE4X5_SICR);
}
static void read_hw_addr(struct dc2114x_priv *priv)
{
u_short tmp, *p = (u_short *)(&priv->enetaddr[0]);
int i, j = 0;
for (i = 0; i < (ETH_ALEN >> 1); i++) {
tmp = read_srom(priv, DE4X5_APROM, (SROM_HWADD >> 1) + i);
*p = le16_to_cpu(tmp);
j += *p++;
}
if (!j || j == 0x2fffd) {
memset(priv->enetaddr, 0, ETH_ALEN);
debug("Warning: can't read HW address from SROM.\n");
}
}
#if !CONFIG_IS_ENABLED(TULIP_SUPPORT_NON_PCI)
static struct pci_device_id supported[] = {
{ PCI_DEVICE(PCI_VENDOR_ID_DEC, PCI_DEVICE_ID_DEC_TULIP_FAST) },
{ PCI_DEVICE(PCI_VENDOR_ID_DEC, PCI_DEVICE_ID_DEC_21142) },
{ }
};
#endif
static int dc2114x_start(struct udevice *dev)
{
struct dc2114x_priv *priv = dev_get_priv(dev);
int rval;
if (!priv->enetaddr) {
rval = eth_env_get_enetaddr("ethaddr", priv->enetaddr);
if (!rval) {
printf("dc2114x: Err: please set a valid MAC address\n");
return -EINVAL;
}
}
#if !CONFIG_IS_ENABLED(TULIP_SUPPORT_NON_PCI)
/* Ensure we're not sleeping. */
dm_pci_write_config8(dev, PCI_CFDA_PSM, WAKEUP);
#endif
return dc21x4x_init_common(priv);
}
static void dc2114x_stop(struct udevice *dev)
{
struct dc2114x_priv *priv = dev_get_priv(dev);
dc21x4x_halt_common(priv);
#if !CONFIG_IS_ENABLED(TULIP_SUPPORT_NON_PCI)
dm_pci_write_config8(dev, PCI_CFDA_PSM, SLEEP);
#endif
}
static int dc2114x_send(struct udevice *dev, void *packet, int length)
{
struct dc2114x_priv *priv = dev_get_priv(dev);
int ret;
ret = dc21x4x_send_common(priv, packet, length);
return ret ? 0 : -ETIMEDOUT;
}
static int dc2114x_recv(struct udevice *dev, int flags, uchar **packetp)
{
struct dc2114x_priv *priv = dev_get_priv(dev);
int ret;
ret = dc21x4x_recv_check(priv);
if (ret < 0) {
/* Update entry information. */
priv->rx_new = (priv->rx_new + 1) % priv->rx_ring_size;
ret = 0;
}
if (!ret)
return 0;
invalidate_dcache_range((phys_addr_t)net_rx_packets[priv->rx_new], (phys_addr_t)(net_rx_packets[priv->rx_new] + RX_BUFF_SZ));
*packetp = (uchar *)net_rx_packets[priv->rx_new];
return ret - 4;
}
static int dc2114x_free_pkt(struct udevice *dev, uchar *packet, int length)
{
struct dc2114x_priv *priv = dev_get_priv(dev);
priv->rx_ring[priv->rx_new].status = cpu_to_le32(R_OWN);
/* Update entry information. */
priv->rx_new = (priv->rx_new + 1) % priv->rx_ring_size;
return 0;
}
static int dc2114x_read_rom_hwaddr(struct udevice *dev)
{
struct dc2114x_priv *priv = dev_get_priv(dev);
read_hw_addr(priv);
return 0;
}
static int dc2114x_bind(struct udevice *dev)
{
static int card_number = 0;
char name[16];
sprintf(name, "dc2114x#%u", card_number++);
return device_set_name(dev, name);
}
static int dc2114x_probe(struct udevice *dev)
{
struct eth_pdata *plat = dev_get_plat(dev);
struct dc2114x_priv *priv = dev_get_priv(dev);
#if !CONFIG_IS_ENABLED(TULIP_SUPPORT_NON_PCI)
u16 command, status;
u32 iobase;
dm_pci_read_config32(dev, PCI_BASE_ADDRESS_1, &iobase);
iobase &= ~0xf;
debug("dc2114x: DEC 2114x PCI Device @0x%x\n", iobase);
priv->iobase = (void __iomem *)dm_pci_mem_to_phys(dev, iobase);
command = PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER;
dm_pci_write_config16(dev, PCI_COMMAND, command);
dm_pci_read_config16(dev, PCI_COMMAND, &status);
if ((status & command) != command) {
printf("dc2114x: Couldn't enable IO access or Bus Mastering\n");
return -EINVAL;
}
dm_pci_write_config8(dev, PCI_LATENCY_TIMER, 0x60);
#endif
priv->devno = dev;
priv->enetaddr = plat->enetaddr;
priv->rx_ring = (struct de4x5_desc *)map_physmem((phys_addr_t)virt_to_phys(rx_ring), 0, MAP_NOCACHE);
priv->tx_ring = (struct de4x5_desc *)map_physmem((phys_addr_t)virt_to_phys(tx_ring), 0, MAP_NOCACHE);
return 0;
}
#if CONFIG_IS_ENABLED(TULIP_SUPPORT_NON_PCI)
static int dc2114x_of_to_plat(struct udevice *dev)
{
struct eth_pdata *plat = dev_get_plat(dev);
struct dc2114x_priv *priv = dev_get_priv(dev);
plat->iobase = (phys_addr_t)map_physmem((phys_addr_t)devfdt_get_addr(dev), 0, MAP_NOCACHE);
priv->iobase = (void *)plat->iobase;
return 0;
}
#endif
static const struct eth_ops dc2114x_ops = {
.start = dc2114x_start,
.send = dc2114x_send,
.recv = dc2114x_recv,
.stop = dc2114x_stop,
.free_pkt = dc2114x_free_pkt,
.read_rom_hwaddr = dc2114x_read_rom_hwaddr,
};
#if CONFIG_IS_ENABLED(TULIP_SUPPORT_NON_PCI)
static const struct udevice_id dc2114x_eth_ids[] = {
{ .compatible = "dec,dmfe" },
{ .compatible = "tulip,dmfe" },
{ .compatible = "dec,dc2114x" },
{ .compatible = "tulip,dc2114x" },
{ }
};
#endif
U_BOOT_DRIVER(eth_dc2114x) = {
.name = "eth_dc2114x",
.id = UCLASS_ETH,
#if CONFIG_IS_ENABLED(TULIP_SUPPORT_NON_PCI)
.of_match = dc2114x_eth_ids,
.of_to_plat = dc2114x_of_to_plat,
#endif
.bind = dc2114x_bind,
.probe = dc2114x_probe,
.ops = &dc2114x_ops,
.priv_auto = sizeof(struct dc2114x_priv),
.plat_auto = sizeof(struct eth_pdata),
};
#if !CONFIG_IS_ENABLED(TULIP_SUPPORT_NON_PCI)
U_BOOT_PCI_DEVICE(eth_dc2114x, supported);
#endif