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Sansa clip zip: use a state machine for scanning buttons to avoid busy-waits

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@30871 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Bertrik Sikken 2011-10-30 20:15:08 +00:00
parent 539fb71b9d
commit eb7cf73dcb
1 changed files with 55 additions and 41 deletions
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96
firmware/target/arm/as3525/sansa-clipzip/button-clipzip.c
View file

@ -27,6 +27,59 @@
#include "kernel.h" #include "kernel.h"
#include "system-target.h" #include "system-target.h"
static int keyscan(void)
{
static int buttons = 0;
static int row = 1;
switch (row) {
case 1:
/* read row 1 */
buttons &= ~(BUTTON_RIGHT | BUTTON_SELECT | BUTTON_UP);
if (GPIOC_PIN(3)) {
buttons |= BUTTON_RIGHT;
}
if (GPIOC_PIN(4)) {
buttons |= BUTTON_SELECT;
}
if (GPIOC_PIN(5)) {
buttons |= BUTTON_UP;
}
/* prepare row 2 */
GPIOC_PIN(1) = 0;
GPIOC_PIN(2) = (1 << 2);
row = 2;
break;
case 2:
/* read row 2 */
buttons &= ~(BUTTON_HOME | BUTTON_DOWN | BUTTON_LEFT);
if (GPIOC_PIN(3)) {
buttons |= BUTTON_HOME;
}
if (GPIOC_PIN(4)) {
buttons |= BUTTON_DOWN;
}
if (GPIOC_PIN(5)) {
buttons |= BUTTON_LEFT;
}
/* prepare row 1 */
GPIOC_PIN(1) = (1 << 1);
GPIOC_PIN(2) = 0;
row = 1;
break;
default:
row = 1;
break;
}
return buttons;
}
void button_init_device(void) void button_init_device(void)
{ {
/* GPIO A6, A7 and D6 are direct button inputs */ /* GPIO A6, A7 and D6 are direct button inputs */
@ -39,15 +92,6 @@ void button_init_device(void)
GPIOC_DIR &= ~((1 << 3) | (1 << 4) | (1 << 5)); GPIOC_DIR &= ~((1 << 3) | (1 << 4) | (1 << 5));
} }
/* TODO:
Instead of using udelay to wait for buttons to settle, we could use a
simple state machine to alternate between key matrix rows (like we do on
the clip) and this way avoid burning cycles in the udelay.
TODO:
Figure out the real mappings from GPIOs to buttons.
The current mapping is just an educated guess.
*/
int button_read_device(void) int button_read_device(void)
{ {
int buttons = 0; int buttons = 0;
@ -65,38 +109,8 @@ int button_read_device(void)
buttons |= BUTTON_VOL_UP; buttons |= BUTTON_VOL_UP;
} }
/* key matrix buttons, first row */ /* keyscan buttons */
GPIOC_PIN(1) = (1 << 1); buttons |= keyscan();
GPIOC_PIN(2) = 0;
udelay(500);
if (GPIOC_PIN(3)) {
buttons |= BUTTON_RIGHT;
}
if (GPIOC_PIN(4)) {
buttons |= BUTTON_SELECT;
}
if (GPIOC_PIN(5)) {
buttons |= BUTTON_UP;
}
/* key matrix buttons, second row */
GPIOC_PIN(1) = 0;
GPIOC_PIN(2) = (1 << 2);
udelay(500);
if (GPIOC_PIN(3)) {
buttons |= BUTTON_HOME;
}
if (GPIOC_PIN(4)) {
buttons |= BUTTON_DOWN;
}
if (GPIOC_PIN(5)) {
buttons |= BUTTON_LEFT;
}
/* deselect scan rows */
GPIOC_PIN(2) = 0;
return buttons; return buttons;
} }