misc: panel: Abstract temporary backlight handling

Currently the periodic scan timer is used for three purposes,
entangling keypad and display handling, which are both optional:
  1. Scanning the keypad,
  2. Flashing the backlight when a key is pressed,
  3. Disabling temporary backlighting after a fixed period of time.

Abstract the second purpose using a new lcd_poke() function.
Make the non-periodic temporary backlight handling independent from
keypad handling by converting it to a delayed workqueue.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/misc/panel.c b/drivers/misc/panel.c
index 9c7b00951c22b1c27ec2b69b0843359f3e02def9..ef2ece0f26afc6b513ff72dabb08e2ac81c13a56 100644 (file)
--- a/drivers/misc/panel.c
+++ b/drivers/misc/panel.c
@@ -56,6 +56,7 @@
 #include <linux/list.h>
 #include <linux/notifier.h>
 #include <linux/reboot.h>
+#include <linux/workqueue.h>
 #include <generated/utsrelease.h>
 
 #include <linux/io.h>
@@ -75,8 +76,8 @@
 /* a key repeats this times INPUT_POLL_TIME */
 #define KEYPAD_REP_DELAY       (2)
 
-/* keep the light on this times INPUT_POLL_TIME for each flash */
-#define FLASH_LIGHT_TEMPO      (200)
+/* keep the light on this many seconds for each flash */
+#define FLASH_LIGHT_TEMPO      (4)
 
 /* converts an r_str() input to an active high, bits string : 000BAOSE */
 #define PNL_PINPUT(a)          ((((unsigned char)(a)) ^ 0x7F) >> 3)
@@ -252,7 +253,10 @@ static struct {
        int hwidth;
        int charset;
        int proto;
-       int light_tempo;
+
+       struct delayed_work bl_work;
+       struct mutex bl_tempo_lock;     /* Protects access to bl_tempo */
+       bool bl_tempo;
 
        /* TODO: use union here? */
        struct {
@@ -657,8 +661,6 @@ static void lcd_get_bits(unsigned int port, int *val)
        }
 }
 
-static void init_scan_timer(void);
-
 /* sets data port bits according to current signals values */
 static int set_data_bits(void)
 {
@@ -790,11 +792,8 @@ static void lcd_send_serial(int byte)
 }
 
 /* turn the backlight on or off */
-static void lcd_backlight(int on)
+static void __lcd_backlight(int on)
 {
-       if (lcd.pins.bl == PIN_NONE)
-               return;
-
        /* The backlight is activated by setting the AUTOFEED line to +5V  */
        spin_lock_irq(&pprt_lock);
        if (on)
@@ -805,6 +804,44 @@ static void lcd_backlight(int on)
        spin_unlock_irq(&pprt_lock);
 }
 
+static void lcd_backlight(int on)
+{
+       if (lcd.pins.bl == PIN_NONE)
+               return;
+
+       mutex_lock(&lcd.bl_tempo_lock);
+       if (!lcd.bl_tempo)
+               __lcd_backlight(on);
+       mutex_unlock(&lcd.bl_tempo_lock);
+}
+
+static void lcd_bl_off(struct work_struct *work)
+{
+       mutex_lock(&lcd.bl_tempo_lock);
+       if (lcd.bl_tempo) {
+               lcd.bl_tempo = false;
+               if (!(lcd.flags & LCD_FLAG_L))
+                       __lcd_backlight(0);
+       }
+       mutex_unlock(&lcd.bl_tempo_lock);
+}
+
+/* turn the backlight on for a little while */
+static void lcd_poke(void)
+{
+       if (lcd.pins.bl == PIN_NONE)
+               return;
+
+       cancel_delayed_work_sync(&lcd.bl_work);
+
+       mutex_lock(&lcd.bl_tempo_lock);
+       if (!lcd.bl_tempo && !(lcd.flags & LCD_FLAG_L))
+               __lcd_backlight(1);
+       lcd.bl_tempo = true;
+       schedule_delayed_work(&lcd.bl_work, FLASH_LIGHT_TEMPO * HZ);
+       mutex_unlock(&lcd.bl_tempo_lock);
+}
+
 /* send a command to the LCD panel in serial mode */
 static void lcd_write_cmd_s(int cmd)
 {
@@ -1099,13 +1136,8 @@ static inline int handle_lcd_special_code(void)
                processed = 1;
                break;
        case '*':
-               /* flash back light using the keypad timer */
-               if (scan_timer.function) {
-                       if (lcd.light_tempo == 0 &&
-                           ((lcd.flags & LCD_FLAG_L) == 0))
-                               lcd_backlight(1);
-                       lcd.light_tempo = FLASH_LIGHT_TEMPO;
-               }
+               /* flash back light */
+               lcd_poke();
                processed = 1;
                break;
        case 'f':       /* Small Font */
@@ -1275,16 +1307,8 @@ static inline int handle_lcd_special_code(void)
                                                      ? LCD_CMD_TWO_LINES
                                                                      : 0));
                /* check whether L flag was changed */
-               else if ((oldflags ^ lcd.flags) & (LCD_FLAG_L)) {
-                       if (lcd.flags & (LCD_FLAG_L))
-                               lcd_backlight(1);
-                       else if (lcd.light_tempo == 0)
-                               /*
-                                * switch off the light only when the tempo
-                                * lighting is gone
-                                */
-                               lcd_backlight(0);
-               }
+               else if ((oldflags ^ lcd.flags) & (LCD_FLAG_L))
+                       lcd_backlight(!!(lcd.flags & LCD_FLAG_L));
        }
 
        return processed;
@@ -1615,8 +1639,10 @@ static void lcd_init(void)
        else
                lcd_char_conv = NULL;
 
-       if (lcd.pins.bl != PIN_NONE)
-               init_scan_timer();
+       if (lcd.pins.bl != PIN_NONE) {
+               mutex_init(&lcd.bl_tempo_lock);
+               INIT_DELAYED_WORK(&lcd.bl_work, lcd_bl_off);
+       }
 
        pin_to_bits(lcd.pins.e, lcd_bits[LCD_PORT_D][LCD_BIT_E],
                    lcd_bits[LCD_PORT_C][LCD_BIT_E]);
@@ -1984,19 +2010,8 @@ static void panel_scan_timer(void)
                        panel_process_inputs();
        }
 
-       if (lcd.enabled && lcd.initialized) {
-               if (keypressed) {
-                       if (lcd.light_tempo == 0 &&
-                           ((lcd.flags & LCD_FLAG_L) == 0))
-                               lcd_backlight(1);
-                       lcd.light_tempo = FLASH_LIGHT_TEMPO;
-               } else if (lcd.light_tempo > 0) {
-                       lcd.light_tempo--;
-                       if (lcd.light_tempo == 0 &&
-                           ((lcd.flags & LCD_FLAG_L) == 0))
-                               lcd_backlight(0);
-               }
-       }
+       if (keypressed && lcd.enabled && lcd.initialized)
+               lcd_poke();
 
        mod_timer(&scan_timer, jiffies + INPUT_POLL_TIME);
 }
@@ -2265,6 +2280,10 @@ static void panel_detach(struct parport *port)
        if (lcd.enabled) {
                panel_lcd_print("\x0cLCD driver unloaded.\x1b[Lc\x1b[Lb\x1b[L-");
                misc_deregister(&lcd_dev);
+               if (lcd.pins.bl != PIN_NONE) {
+                       cancel_delayed_work_sync(&lcd.bl_work);
+                       __lcd_backlight(0);
+               }
                lcd.initialized = false;
        }