From: Grant Grundler Date: Sat, 22 Oct 2005 02:46:18 +0000 (-0400) Subject: [PARISC] Use work queue in LED/LCD driver instead of tasklet. X-Git-Tag: v2.6.15-rc1~732^2^2~9^2~35 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3499495205a676d85fcc2f3c28e35ec9b43c47e3;p=linux-2.6 [PARISC] Use work queue in LED/LCD driver instead of tasklet. 2.6.12-rc1-pa6 use work queue in LED/LCD driver instead of tasklet. Main advantage is it allows use of msleep() in the led_LCD_driver to "atomically" perform two MMIO writes (CMD, then DATA). Lead to nice cleanup of the main led_work_func() and led_LCD_driver(). Kudos to David for being persistent. From: David Pye Signed-off-by: Grant Grundler Signed-off-by: Kyle McMartin --- diff --git a/arch/parisc/kernel/time.c b/arch/parisc/kernel/time.c index 163cdf39be..bc979e1abd 100644 --- a/arch/parisc/kernel/time.c +++ b/arch/parisc/kernel/time.c @@ -89,14 +89,6 @@ irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) } } -#ifdef CONFIG_CHASSIS_LCD_LED - /* Only schedule the led tasklet on cpu 0, and only if it - * is enabled. - */ - if (cpu == 0 && !atomic_read(&led_tasklet.count)) - tasklet_schedule(&led_tasklet); -#endif - /* check soft power switch status */ if (cpu == 0 && !atomic_read(&power_tasklet.count)) tasklet_schedule(&power_tasklet); diff --git a/drivers/parisc/led.c b/drivers/parisc/led.c index 286902298e..95bd07b8b6 100644 --- a/drivers/parisc/led.c +++ b/drivers/parisc/led.c @@ -18,6 +18,9 @@ * Changes: * - Audit copy_from_user in led_proc_write. * Daniele Bellucci + * - Switch from using a tasklet to a work queue, so the led_LCD_driver + * can sleep. + * David Pye */ #include @@ -37,6 +40,7 @@ #include #include #include +#include #include #include #include @@ -47,25 +51,30 @@ #include /* The control of the LEDs and LCDs on PARISC-machines have to be done - completely in software. The necessary calculations are done in a tasklet - which is scheduled at every timer interrupt and since the calculations - may consume relatively much CPU-time some of the calculations can be + 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 = -1; -static int led_heartbeat = 1; -static int led_diskio = 1; -static int led_lanrxtx = 1; +static unsigned char lastleds; /* LED state from most recent update */ +static unsigned int led_heartbeat = 1; +static unsigned int led_diskio = 1; +static unsigned int led_lanrxtx = 1; static char lcd_text[32]; static char lcd_text_default[32]; + +static struct workqueue_struct *led_wq; +static void led_work_func(void *); +static DECLARE_WORK(led_task, led_work_func, NULL); + #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 */ @@ -116,12 +125,27 @@ lcd_info __attribute__((aligned(8))) = #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 ); + + /* Create the work queue and queue the LED task */ + led_wq = create_singlethread_workqueue("led_wq"); + queue_work(led_wq, &led_task); + + return 0; +} + +device_initcall(start_task); /* ptr to LCD/LED-specific function */ static void (*led_func_ptr) (unsigned char); -#define LED_HASLCD 1 -#define LED_NOLCD 0 #ifdef CONFIG_PROC_FS static int led_proc_read(char *page, char **start, off_t off, int count, int *eof, void *data) @@ -286,52 +310,35 @@ static void led_LASI_driver(unsigned char leds) /* ** ** led_LCD_driver() - ** - ** The logic of the LCD driver is, that we write at every scheduled call - ** only to one of LCD_CMD_REG _or_ LCD_DATA_REG - registers. - ** That way we don't need to let this tasklet busywait for min_cmd_delay - ** milliseconds. - ** - ** TODO: check the value of "min_cmd_delay" against the value of HZ. ** */ static void led_LCD_driver(unsigned char leds) { - static int last_index; /* 0:heartbeat, 1:disk, 2:lan_in, 3:lan_out */ - static int last_was_cmd;/* 0: CMD was written last, 1: DATA was last */ - struct lcd_block *block_ptr; - int value; - - switch (last_index) { - case 0: block_ptr = &lcd_info.heartbeat; - value = leds & LED_HEARTBEAT; - break; - case 1: block_ptr = &lcd_info.disk_io; - value = leds & LED_DISK_IO; - break; - case 2: block_ptr = &lcd_info.lan_rcv; - value = leds & LED_LAN_RCV; - break; - case 3: block_ptr = &lcd_info.lan_tx; - value = leds & LED_LAN_TX; - break; - default: /* should never happen: */ - return; - } - - if (last_was_cmd) { - /* write the value to the LCD data port */ - gsc_writeb( value ? block_ptr->on : block_ptr->off, LCD_DATA_REG ); - } else { - /* write the command-byte to the LCD command register */ - gsc_writeb( block_ptr->command, LCD_CMD_REG ); - } + static int i; + static unsigned char mask[4] = { LED_HEARTBEAT, LED_DISK_IO, + LED_LAN_RCV, LED_LAN_TX }; - /* now update the vars for the next interrupt iteration */ - if (++last_was_cmd == 2) { /* switch between cmd & data */ - last_was_cmd = 0; - if (++last_index == 4) - last_index = 0; /* switch back to heartbeat index */ + 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); + } } } @@ -356,7 +363,7 @@ static __inline__ int led_get_net_activity(void) rx_total = tx_total = 0; - /* we are running as tasklet, so locking dev_base + /* we are running as a workqueue task, so locking dev_base * for reading should be OK */ read_lock(&dev_base_lock); rcu_read_lock(); @@ -405,7 +412,7 @@ static __inline__ int led_get_diskio_activity(void) static unsigned long last_pgpgin, last_pgpgout; struct page_state pgstat; int changed; - + get_full_page_state(&pgstat); /* get no of sectors in & out */ /* Just use a very simple calculation here. Do not care about overflow, @@ -413,86 +420,70 @@ static __inline__ int led_get_diskio_activity(void) changed = (pgstat.pgpgin != last_pgpgin) || (pgstat.pgpgout != last_pgpgout); last_pgpgin = pgstat.pgpgin; last_pgpgout = pgstat.pgpgout; - + return (changed ? LED_DISK_IO : 0); } /* - ** led_tasklet_func() + ** led_work_func() ** - ** is scheduled at every timer interrupt from time.c and - ** updates the chassis LCD/LED + ** 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*6/100) -#define HEARTBEAT_2ND_RANGE_START (HZ*22/100) +#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 NORMALIZED_COUNT(count) (count/(HZ/100)) +#define LED_UPDATE_INTERVAL (1 + (HZ*19/1000)) -static void led_tasklet_func(unsigned long unused) +static void led_work_func (void *unused) { - static unsigned char lastleds; - unsigned char currentleds; /* stores current value of the LEDs */ - static unsigned long count; /* static incremented value, not wrapped */ + 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 local counters */ - ++count; - if (++count_HZ == HZ) + /* increment the heartbeat timekeeper */ + count_HZ += jiffies - last_jiffies; + last_jiffies = jiffies; + if (count_HZ >= HZ) count_HZ = 0; - currentleds = lastleds; - - if (led_heartbeat) - { - /* flash heartbeat-LED like a real heart (2 x short then a long delay) */ - if (count_HZ=HEARTBEAT_2ND_RANGE_START && count_HZ= HEARTBEAT_2ND_RANGE_START && + count_HZ < HEARTBEAT_2ND_RANGE_END)) + currentleds |= LED_HEARTBEAT; } - /* avoid to calculate diskio-stats at same irq as netio-stats */ - if (led_diskio && (NORMALIZED_COUNT(count) & 7) == 0) - { - currentleds &= ~LED_DISK_IO; - currentleds |= led_get_diskio_activity(); - } + if (likely(led_lanrxtx)) currentleds |= led_get_net_activity(); + if (likely(led_diskio)) currentleds |= led_get_diskio_activity(); /* blink all LEDs twice a second if we got an Oops (HPMC) */ - if (oops_in_progress) { + if (unlikely(oops_in_progress)) currentleds = (count_HZ<=(HZ/2)) ? 0 : 0xff; - } - - /* update the LCD/LEDs */ - if (currentleds != lastleds) { - led_func_ptr(currentleds); - lastleds = currentleds; - } -} -/* main led tasklet struct (scheduled from time.c) */ -DECLARE_TASKLET_DISABLED(led_tasklet, led_tasklet_func, 0); + 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() @@ -522,9 +513,13 @@ static int led_halt(struct notifier_block *nb, unsigned long event, void *buf) default: return NOTIFY_DONE; } - /* completely stop the LED/LCD tasklet */ - tasklet_disable(&led_tasklet); - + /* Cancel the work item and delete the queue */ + if (led_wq) { + cancel_rearming_delayed_workqueue(led_wq, &led_task); + destroy_workqueue(led_wq); + led_wq = NULL; + } + if (lcd_info.model == DISPLAY_MODEL_LCD) lcd_print(txt); else @@ -559,7 +554,6 @@ int __init register_led_driver(int model, unsigned long cmd_reg, unsigned long d printk(KERN_INFO "LCD display at %lx,%lx registered\n", LCD_CMD_REG , LCD_DATA_REG); led_func_ptr = led_LCD_driver; - lcd_print( lcd_text_default ); led_type = LED_HASLCD; break; @@ -589,9 +583,11 @@ int __init register_led_driver(int model, unsigned long cmd_reg, unsigned long d initialized++; register_reboot_notifier(&led_notifier); - /* start the led tasklet for the first time */ - tasklet_enable(&led_tasklet); - + /* Ensure the work is queued */ + if (led_wq) { + queue_work(led_wq, &led_task); + } + return 0; } @@ -626,8 +622,8 @@ void __init register_led_regions(void) ** lcd_print() ** ** Displays the given string on the LCD-Display of newer machines. - ** lcd_print() disables the timer-based led tasklet during its - ** execution and enables it afterwards again. + ** 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( char *str ) @@ -637,12 +633,13 @@ int lcd_print( char *str ) if (!led_func_ptr || lcd_info.model != DISPLAY_MODEL_LCD) return 0; - /* temporarily disable the led tasklet */ - tasklet_disable(&led_tasklet); + /* temporarily disable the led work task */ + if (led_wq) + cancel_rearming_delayed_workqueue(led_wq, &led_task); /* copy display string to buffer for procfs */ strlcpy(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); @@ -656,8 +653,10 @@ int lcd_print( char *str ) udelay(lcd_info.min_cmd_delay); } - /* re-enable the led tasklet */ - tasklet_enable(&led_tasklet); + /* re-queue the work */ + if (led_wq) { + queue_work(led_wq, &led_task); + } return lcd_info.lcd_width; } diff --git a/include/asm-parisc/led.h b/include/asm-parisc/led.h index 1ac8ab6c58..efadfd543e 100644 --- a/include/asm-parisc/led.h +++ b/include/asm-parisc/led.h @@ -23,9 +23,6 @@ #define LED_CMD_REG_NONE 0 /* NULL == no addr for the cmd register */ -/* led tasklet struct */ -extern struct tasklet_struct led_tasklet; - /* register_led_driver() */ int __init register_led_driver(int model, unsigned long cmd_reg, unsigned long data_reg);