diff options
Diffstat (limited to 'drivers/parisc/led.c')
| -rw-r--r-- | drivers/parisc/led.c | 780 |
1 files changed, 780 insertions, 0 deletions
diff --git a/drivers/parisc/led.c b/drivers/parisc/led.c new file mode 100644 index 000000000..3737c1021 --- /dev/null +++ b/drivers/parisc/led.c @@ -0,0 +1,780 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Chassis LCD/LED driver for HP-PARISC workstations + * + * (c) Copyright 2000 Red Hat Software + * (c) Copyright 2000 Helge Deller <hdeller@redhat.com> + * (c) Copyright 2001-2009 Helge Deller <deller@gmx.de> + * (c) Copyright 2001 Randolph Chung <tausq@debian.org> + * + * TODO: + * - speed-up calculations with inlined assembler + * - interface to write to second row of LCD from /proc (if technically possible) + * + * Changes: + * - Audit copy_from_user in led_proc_write. + * Daniele Bellucci <bellucda@tiscali.it> + * - Switch from using a tasklet to a work queue, so the led_LCD_driver + * can sleep. + * David Pye <dmp@davidmpye.dyndns.org> + */ + +#include <linux/module.h> +#include <linux/stddef.h> /* for offsetof() */ +#include <linux/init.h> +#include <linux/types.h> +#include <linux/ioport.h> +#include <linux/utsname.h> +#include <linux/capability.h> +#include <linux/delay.h> +#include <linux/netdevice.h> +#include <linux/inetdevice.h> +#include <linux/in.h> +#include <linux/interrupt.h> +#include <linux/kernel_stat.h> +#include <linux/reboot.h> +#include <linux/proc_fs.h> +#include <linux/seq_file.h> +#include <linux/ctype.h> +#include <linux/blkdev.h> +#include <linux/workqueue.h> +#include <linux/rcupdate.h> +#include <asm/io.h> +#include <asm/processor.h> +#include <asm/hardware.h> +#include <asm/param.h> /* HZ */ +#include <asm/led.h> +#include <asm/pdc.h> +#include <linux/uaccess.h> + +/* The control of the LEDs and LCDs on PARISC-machines have to be done + completely in software. The necessary calculations are done in a work queue + task which is scheduled regularly, and since the calculations may consume a + relatively large amount of CPU time, some of the calculations can be + turned off with the following variables (controlled via procfs) */ + +static int led_type __read_mostly = -1; +static unsigned char lastleds; /* LED state from most recent update */ +static unsigned int led_heartbeat __read_mostly = 1; +static unsigned int led_diskio __read_mostly; +static unsigned int led_lanrxtx __read_mostly; +static char lcd_text[32] __read_mostly; +static char lcd_text_default[32] __read_mostly; +static int lcd_no_led_support __read_mostly = 0; /* KittyHawk doesn't support LED on its LCD */ + + +static struct workqueue_struct *led_wq; +static void led_work_func(struct work_struct *); +static DECLARE_DELAYED_WORK(led_task, led_work_func); + +#if 0 +#define DPRINTK(x) printk x +#else +#define DPRINTK(x) +#endif + +struct lcd_block { + unsigned char command; /* stores the command byte */ + unsigned char on; /* value for turning LED on */ + unsigned char off; /* value for turning LED off */ +}; + +/* Structure returned by PDC_RETURN_CHASSIS_INFO */ +/* NOTE: we use unsigned long:16 two times, since the following member + lcd_cmd_reg_addr needs to be 64bit aligned on 64bit PA2.0-machines */ +struct pdc_chassis_lcd_info_ret_block { + unsigned long model:16; /* DISPLAY_MODEL_XXXX */ + unsigned long lcd_width:16; /* width of the LCD in chars (DISPLAY_MODEL_LCD only) */ + unsigned long lcd_cmd_reg_addr; /* ptr to LCD cmd-register & data ptr for LED */ + unsigned long lcd_data_reg_addr; /* ptr to LCD data-register (LCD only) */ + unsigned int min_cmd_delay; /* delay in uS after cmd-write (LCD only) */ + unsigned char reset_cmd1; /* command #1 for writing LCD string (LCD only) */ + unsigned char reset_cmd2; /* command #2 for writing LCD string (LCD only) */ + unsigned char act_enable; /* 0 = no activity (LCD only) */ + struct lcd_block heartbeat; + struct lcd_block disk_io; + struct lcd_block lan_rcv; + struct lcd_block lan_tx; + char _pad; +}; + + +/* LCD_CMD and LCD_DATA for KittyHawk machines */ +#define KITTYHAWK_LCD_CMD F_EXTEND(0xf0190000UL) /* 64bit-ready */ +#define KITTYHAWK_LCD_DATA (KITTYHAWK_LCD_CMD+1) + +/* lcd_info is pre-initialized to the values needed to program KittyHawk LCD's + * HP seems to have used Sharp/Hitachi HD44780 LCDs most of the time. */ +static struct pdc_chassis_lcd_info_ret_block +lcd_info __attribute__((aligned(8))) __read_mostly = +{ + .model = DISPLAY_MODEL_LCD, + .lcd_width = 16, + .lcd_cmd_reg_addr = KITTYHAWK_LCD_CMD, + .lcd_data_reg_addr = KITTYHAWK_LCD_DATA, + .min_cmd_delay = 80, + .reset_cmd1 = 0x80, + .reset_cmd2 = 0xc0, +}; + + +/* direct access to some of the lcd_info variables */ +#define LCD_CMD_REG lcd_info.lcd_cmd_reg_addr +#define LCD_DATA_REG lcd_info.lcd_data_reg_addr +#define LED_DATA_REG lcd_info.lcd_cmd_reg_addr /* LASI & ASP only */ + +#define LED_HASLCD 1 +#define LED_NOLCD 0 + +/* The workqueue must be created at init-time */ +static int start_task(void) +{ + /* Display the default text now */ + if (led_type == LED_HASLCD) lcd_print( lcd_text_default ); + + /* KittyHawk has no LED support on its LCD */ + if (lcd_no_led_support) return 0; + + /* Create the work queue and queue the LED task */ + led_wq = create_singlethread_workqueue("led_wq"); + if (!led_wq) + return -ENOMEM; + + queue_delayed_work(led_wq, &led_task, 0); + + return 0; +} + +device_initcall(start_task); + +/* ptr to LCD/LED-specific function */ +static void (*led_func_ptr) (unsigned char) __read_mostly; + +#ifdef CONFIG_PROC_FS +static int led_proc_show(struct seq_file *m, void *v) +{ + switch ((long)m->private) + { + case LED_NOLCD: + seq_printf(m, "Heartbeat: %d\n", led_heartbeat); + seq_printf(m, "Disk IO: %d\n", led_diskio); + seq_printf(m, "LAN Rx/Tx: %d\n", led_lanrxtx); + break; + case LED_HASLCD: + seq_printf(m, "%s\n", lcd_text); + break; + default: + return 0; + } + return 0; +} + +static int led_proc_open(struct inode *inode, struct file *file) +{ + return single_open(file, led_proc_show, pde_data(inode)); +} + + +static ssize_t led_proc_write(struct file *file, const char __user *buf, + size_t count, loff_t *pos) +{ + void *data = pde_data(file_inode(file)); + char *cur, lbuf[32]; + int d; + + if (!capable(CAP_SYS_ADMIN)) + return -EACCES; + + if (count >= sizeof(lbuf)) + count = sizeof(lbuf)-1; + + if (copy_from_user(lbuf, buf, count)) + return -EFAULT; + lbuf[count] = 0; + + cur = lbuf; + + switch ((long)data) + { + case LED_NOLCD: + d = *cur++ - '0'; + if (d != 0 && d != 1) goto parse_error; + led_heartbeat = d; + + if (*cur++ != ' ') goto parse_error; + + d = *cur++ - '0'; + if (d != 0 && d != 1) goto parse_error; + led_diskio = d; + + if (*cur++ != ' ') goto parse_error; + + d = *cur++ - '0'; + if (d != 0 && d != 1) goto parse_error; + led_lanrxtx = d; + + break; + case LED_HASLCD: + if (*cur && cur[strlen(cur)-1] == '\n') + cur[strlen(cur)-1] = 0; + if (*cur == 0) + cur = lcd_text_default; + lcd_print(cur); + break; + default: + return 0; + } + + return count; + +parse_error: + if ((long)data == LED_NOLCD) + printk(KERN_CRIT "Parse error: expect \"n n n\" (n == 0 or 1) for heartbeat,\ndisk io and lan tx/rx indicators\n"); + return -EINVAL; +} + +static const struct proc_ops led_proc_ops = { + .proc_open = led_proc_open, + .proc_read = seq_read, + .proc_lseek = seq_lseek, + .proc_release = single_release, + .proc_write = led_proc_write, +}; + +static int __init led_create_procfs(void) +{ + struct proc_dir_entry *proc_pdc_root = NULL; + struct proc_dir_entry *ent; + + if (led_type == -1) return -1; + + proc_pdc_root = proc_mkdir("pdc", NULL); + if (!proc_pdc_root) return -1; + + if (!lcd_no_led_support) + { + ent = proc_create_data("led", 0644, proc_pdc_root, + &led_proc_ops, (void *)LED_NOLCD); /* LED */ + if (!ent) return -1; + } + + if (led_type == LED_HASLCD) + { + ent = proc_create_data("lcd", 0644, proc_pdc_root, + &led_proc_ops, (void *)LED_HASLCD); /* LCD */ + if (!ent) return -1; + } + + return 0; +} +#endif + +/* + ** + ** led_ASP_driver() + ** + */ +#define LED_DATA 0x01 /* data to shift (0:on 1:off) */ +#define LED_STROBE 0x02 /* strobe to clock data */ +static void led_ASP_driver(unsigned char leds) +{ + int i; + + leds = ~leds; + for (i = 0; i < 8; i++) { + unsigned char value; + value = (leds & 0x80) >> 7; + gsc_writeb( value, LED_DATA_REG ); + gsc_writeb( value | LED_STROBE, LED_DATA_REG ); + leds <<= 1; + } +} + + +/* + ** + ** led_LASI_driver() + ** + */ +static void led_LASI_driver(unsigned char leds) +{ + leds = ~leds; + gsc_writeb( leds, LED_DATA_REG ); +} + + +/* + ** + ** led_LCD_driver() + ** + */ +static void led_LCD_driver(unsigned char leds) +{ + static int i; + static unsigned char mask[4] = { LED_HEARTBEAT, LED_DISK_IO, + LED_LAN_RCV, LED_LAN_TX }; + + static struct lcd_block * blockp[4] = { + &lcd_info.heartbeat, + &lcd_info.disk_io, + &lcd_info.lan_rcv, + &lcd_info.lan_tx + }; + + /* Convert min_cmd_delay to milliseconds */ + unsigned int msec_cmd_delay = 1 + (lcd_info.min_cmd_delay / 1000); + + for (i=0; i<4; ++i) + { + if ((leds & mask[i]) != (lastleds & mask[i])) + { + gsc_writeb( blockp[i]->command, LCD_CMD_REG ); + msleep(msec_cmd_delay); + + gsc_writeb( leds & mask[i] ? blockp[i]->on : + blockp[i]->off, LCD_DATA_REG ); + msleep(msec_cmd_delay); + } + } +} + + +/* + ** + ** led_get_net_activity() + ** + ** calculate if there was TX- or RX-throughput on the network interfaces + ** (analog to dev_get_info() from net/core/dev.c) + ** + */ +static __inline__ int led_get_net_activity(void) +{ +#ifndef CONFIG_NET + return 0; +#else + static u64 rx_total_last, tx_total_last; + u64 rx_total, tx_total; + struct net_device *dev; + int retval; + + rx_total = tx_total = 0; + + /* we are running as a workqueue task, so we can use an RCU lookup */ + rcu_read_lock(); + for_each_netdev_rcu(&init_net, dev) { + const struct rtnl_link_stats64 *stats; + struct rtnl_link_stats64 temp; + struct in_device *in_dev = __in_dev_get_rcu(dev); + if (!in_dev || !in_dev->ifa_list) + continue; + if (ipv4_is_loopback(in_dev->ifa_list->ifa_local)) + continue; + stats = dev_get_stats(dev, &temp); + rx_total += stats->rx_packets; + tx_total += stats->tx_packets; + } + rcu_read_unlock(); + + retval = 0; + + if (rx_total != rx_total_last) { + rx_total_last = rx_total; + retval |= LED_LAN_RCV; + } + + if (tx_total != tx_total_last) { + tx_total_last = tx_total; + retval |= LED_LAN_TX; + } + + return retval; +#endif +} + + +/* + ** + ** led_get_diskio_activity() + ** + ** calculate if there was disk-io in the system + ** + */ +static __inline__ int led_get_diskio_activity(void) +{ + static unsigned long last_pgpgin, last_pgpgout; + unsigned long events[NR_VM_EVENT_ITEMS]; + int changed; + + all_vm_events(events); + + /* Just use a very simple calculation here. Do not care about overflow, + since we only want to know if there was activity or not. */ + changed = (events[PGPGIN] != last_pgpgin) || + (events[PGPGOUT] != last_pgpgout); + last_pgpgin = events[PGPGIN]; + last_pgpgout = events[PGPGOUT]; + + return (changed ? LED_DISK_IO : 0); +} + + + +/* + ** led_work_func() + ** + ** manages when and which chassis LCD/LED gets updated + + TODO: + - display load average (older machines like 715/64 have 4 "free" LED's for that) + - optimizations + */ + +#define HEARTBEAT_LEN (HZ*10/100) +#define HEARTBEAT_2ND_RANGE_START (HZ*28/100) +#define HEARTBEAT_2ND_RANGE_END (HEARTBEAT_2ND_RANGE_START + HEARTBEAT_LEN) + +#define LED_UPDATE_INTERVAL (1 + (HZ*19/1000)) + +static void led_work_func (struct work_struct *unused) +{ + static unsigned long last_jiffies; + static unsigned long count_HZ; /* counter in range 0..HZ */ + unsigned char currentleds = 0; /* stores current value of the LEDs */ + + /* exit if not initialized */ + if (!led_func_ptr) + return; + + /* increment the heartbeat timekeeper */ + count_HZ += jiffies - last_jiffies; + last_jiffies = jiffies; + if (count_HZ >= HZ) + count_HZ = 0; + + if (likely(led_heartbeat)) + { + /* flash heartbeat-LED like a real heart + * (2 x short then a long delay) + */ + if (count_HZ < HEARTBEAT_LEN || + (count_HZ >= HEARTBEAT_2ND_RANGE_START && + count_HZ < HEARTBEAT_2ND_RANGE_END)) + currentleds |= LED_HEARTBEAT; + } + + if (likely(led_lanrxtx)) currentleds |= led_get_net_activity(); + if (likely(led_diskio)) currentleds |= led_get_diskio_activity(); + + /* blink LEDs if we got an Oops (HPMC) */ + if (unlikely(oops_in_progress)) { + if (boot_cpu_data.cpu_type >= pcxl2) { + /* newer machines don't have loadavg. LEDs, so we + * let all LEDs blink twice per second instead */ + currentleds = (count_HZ <= (HZ/2)) ? 0 : 0xff; + } else { + /* old machines: blink loadavg. LEDs twice per second */ + if (count_HZ <= (HZ/2)) + currentleds &= ~(LED4|LED5|LED6|LED7); + else + currentleds |= (LED4|LED5|LED6|LED7); + } + } + + if (currentleds != lastleds) + { + led_func_ptr(currentleds); /* Update the LCD/LEDs */ + lastleds = currentleds; + } + + queue_delayed_work(led_wq, &led_task, LED_UPDATE_INTERVAL); +} + +/* + ** led_halt() + ** + ** called by the reboot notifier chain at shutdown and stops all + ** LED/LCD activities. + ** + */ + +static int led_halt(struct notifier_block *, unsigned long, void *); + +static struct notifier_block led_notifier = { + .notifier_call = led_halt, +}; +static int notifier_disabled = 0; + +static int led_halt(struct notifier_block *nb, unsigned long event, void *buf) +{ + char *txt; + + if (notifier_disabled) + return NOTIFY_OK; + + notifier_disabled = 1; + switch (event) { + case SYS_RESTART: txt = "SYSTEM RESTART"; + break; + case SYS_HALT: txt = "SYSTEM HALT"; + break; + case SYS_POWER_OFF: txt = "SYSTEM POWER OFF"; + break; + default: return NOTIFY_DONE; + } + + /* Cancel the work item and delete the queue */ + if (led_wq) { + cancel_delayed_work_sync(&led_task); + destroy_workqueue(led_wq); + led_wq = NULL; + } + + if (lcd_info.model == DISPLAY_MODEL_LCD) + lcd_print(txt); + else + if (led_func_ptr) + led_func_ptr(0xff); /* turn all LEDs ON */ + + return NOTIFY_OK; +} + +/* + ** register_led_driver() + ** + ** registers an external LED or LCD for usage by this driver. + ** currently only LCD-, LASI- and ASP-style LCD/LED's are supported. + ** + */ + +int __init register_led_driver(int model, unsigned long cmd_reg, unsigned long data_reg) +{ + static int initialized; + + if (initialized || !data_reg) + return 1; + + lcd_info.model = model; /* store the values */ + LCD_CMD_REG = (cmd_reg == LED_CMD_REG_NONE) ? 0 : cmd_reg; + + switch (lcd_info.model) { + case DISPLAY_MODEL_LCD: + LCD_DATA_REG = data_reg; + printk(KERN_INFO "LCD display at %lx,%lx registered\n", + LCD_CMD_REG , LCD_DATA_REG); + led_func_ptr = led_LCD_driver; + led_type = LED_HASLCD; + break; + + case DISPLAY_MODEL_LASI: + /* Skip to register LED in QEMU */ + if (running_on_qemu) + return 1; + LED_DATA_REG = data_reg; + led_func_ptr = led_LASI_driver; + printk(KERN_INFO "LED display at %lx registered\n", LED_DATA_REG); + led_type = LED_NOLCD; + break; + + case DISPLAY_MODEL_OLD_ASP: + LED_DATA_REG = data_reg; + led_func_ptr = led_ASP_driver; + printk(KERN_INFO "LED (ASP-style) display at %lx registered\n", + LED_DATA_REG); + led_type = LED_NOLCD; + break; + + default: + printk(KERN_ERR "%s: Wrong LCD/LED model %d !\n", + __func__, lcd_info.model); + return 1; + } + + /* mark the LCD/LED driver now as initialized and + * register to the reboot notifier chain */ + initialized++; + register_reboot_notifier(&led_notifier); + + /* Ensure the work is queued */ + if (led_wq) { + queue_delayed_work(led_wq, &led_task, 0); + } + + return 0; +} + +/* + ** register_led_regions() + ** + ** register_led_regions() registers the LCD/LED regions for /procfs. + ** At bootup - where the initialisation of the LCD/LED normally happens - + ** not all internal structures of request_region() are properly set up, + ** so that we delay the led-registration until after busdevices_init() + ** has been executed. + ** + */ + +void __init register_led_regions(void) +{ + switch (lcd_info.model) { + case DISPLAY_MODEL_LCD: + request_mem_region((unsigned long)LCD_CMD_REG, 1, "lcd_cmd"); + request_mem_region((unsigned long)LCD_DATA_REG, 1, "lcd_data"); + break; + case DISPLAY_MODEL_LASI: + case DISPLAY_MODEL_OLD_ASP: + request_mem_region((unsigned long)LED_DATA_REG, 1, "led_data"); + break; + } +} + + +/* + ** + ** lcd_print() + ** + ** Displays the given string on the LCD-Display of newer machines. + ** lcd_print() disables/enables the timer-based led work queue to + ** avoid a race condition while writing the CMD/DATA register pair. + ** + */ +int lcd_print( const char *str ) +{ + int i; + + if (!led_func_ptr || lcd_info.model != DISPLAY_MODEL_LCD) + return 0; + + /* temporarily disable the led work task */ + if (led_wq) + cancel_delayed_work_sync(&led_task); + + /* copy display string to buffer for procfs */ + strscpy(lcd_text, str, sizeof(lcd_text)); + + /* Set LCD Cursor to 1st character */ + gsc_writeb(lcd_info.reset_cmd1, LCD_CMD_REG); + udelay(lcd_info.min_cmd_delay); + + /* Print the string */ + for (i=0; i < lcd_info.lcd_width; i++) { + if (str && *str) + gsc_writeb(*str++, LCD_DATA_REG); + else + gsc_writeb(' ', LCD_DATA_REG); + udelay(lcd_info.min_cmd_delay); + } + + /* re-queue the work */ + if (led_wq) { + queue_delayed_work(led_wq, &led_task, 0); + } + + return lcd_info.lcd_width; +} + +/* + ** led_init() + ** + ** led_init() is called very early in the bootup-process from setup.c + ** and asks the PDC for an usable chassis LCD or LED. + ** If the PDC doesn't return any info, then the LED + ** is detected by lasi.c or asp.c and registered with the + ** above functions lasi_led_init() or asp_led_init(). + ** KittyHawk machines have often a buggy PDC, so that + ** we explicitly check for those machines here. + */ + +int __init led_init(void) +{ + struct pdc_chassis_info chassis_info; + int ret; + + snprintf(lcd_text_default, sizeof(lcd_text_default), + "Linux %s", init_utsname()->release); + + /* Work around the buggy PDC of KittyHawk-machines */ + switch (CPU_HVERSION) { + case 0x580: /* KittyHawk DC2-100 (K100) */ + case 0x581: /* KittyHawk DC3-120 (K210) */ + case 0x582: /* KittyHawk DC3 100 (K400) */ + case 0x583: /* KittyHawk DC3 120 (K410) */ + case 0x58B: /* KittyHawk DC2 100 (K200) */ + printk(KERN_INFO "%s: KittyHawk-Machine (hversion 0x%x) found, " + "LED detection skipped.\n", __FILE__, CPU_HVERSION); + lcd_no_led_support = 1; + goto found; /* use the preinitialized values of lcd_info */ + } + + /* initialize the struct, so that we can check for valid return values */ + lcd_info.model = DISPLAY_MODEL_NONE; + chassis_info.actcnt = chassis_info.maxcnt = 0; + + ret = pdc_chassis_info(&chassis_info, &lcd_info, sizeof(lcd_info)); + if (ret == PDC_OK) { + DPRINTK((KERN_INFO "%s: chassis info: model=%d (%s), " + "lcd_width=%d, cmd_delay=%u,\n" + "%s: sizecnt=%d, actcnt=%ld, maxcnt=%ld\n", + __FILE__, lcd_info.model, + (lcd_info.model==DISPLAY_MODEL_LCD) ? "LCD" : + (lcd_info.model==DISPLAY_MODEL_LASI) ? "LED" : "unknown", + lcd_info.lcd_width, lcd_info.min_cmd_delay, + __FILE__, sizeof(lcd_info), + chassis_info.actcnt, chassis_info.maxcnt)); + DPRINTK((KERN_INFO "%s: cmd=%p, data=%p, reset1=%x, reset2=%x, act_enable=%d\n", + __FILE__, lcd_info.lcd_cmd_reg_addr, + lcd_info.lcd_data_reg_addr, lcd_info.reset_cmd1, + lcd_info.reset_cmd2, lcd_info.act_enable )); + + /* check the results. Some machines have a buggy PDC */ + if (chassis_info.actcnt <= 0 || chassis_info.actcnt != chassis_info.maxcnt) + goto not_found; + + switch (lcd_info.model) { + case DISPLAY_MODEL_LCD: /* LCD display */ + if (chassis_info.actcnt < + offsetof(struct pdc_chassis_lcd_info_ret_block, _pad)-1) + goto not_found; + if (!lcd_info.act_enable) { + DPRINTK((KERN_INFO "PDC prohibited usage of the LCD.\n")); + goto not_found; + } + break; + + case DISPLAY_MODEL_NONE: /* no LED or LCD available */ + printk(KERN_INFO "PDC reported no LCD or LED.\n"); + goto not_found; + + case DISPLAY_MODEL_LASI: /* Lasi style 8 bit LED display */ + if (chassis_info.actcnt != 8 && chassis_info.actcnt != 32) + goto not_found; + break; + + default: + printk(KERN_WARNING "PDC reported unknown LCD/LED model %d\n", + lcd_info.model); + goto not_found; + } /* switch() */ + +found: + /* register the LCD/LED driver */ + register_led_driver(lcd_info.model, LCD_CMD_REG, LCD_DATA_REG); + return 0; + + } else { /* if() */ + DPRINTK((KERN_INFO "pdc_chassis_info call failed with retval = %d\n", ret)); + } + +not_found: + lcd_info.model = DISPLAY_MODEL_NONE; + return 1; +} + +static void __exit led_exit(void) +{ + unregister_reboot_notifier(&led_notifier); + return; +} + +#ifdef CONFIG_PROC_FS +module_init(led_create_procfs) +#endif |