Optimize lcd-ssd1303 driver (clip series)

Saves 100+ bytes (50 of it in iram), saves a bit of power

Internal LCD clock decreased but with added efficiency of drawing routines
loses only around 2 Hz on the scanrate (~75Hz) while fps is slightly increased

Column offsets are now calculated outside the loops saving a few instructions

Passing a LCD_NOP command after lcd_update turns off Data/Cmd# gpio
saving a bit more power

Added a function lcd_write_cmd_triple() that allows 3 commands to be sent at once
when enabled with LCD_USE_FIFO_FOR_COMMANDS it sends them back to back without
checking FIFO status in between or sending to thhe D/C# Gpio.
Makes an assumption about the FIFO being large enough to
accept 3 commands after being emptied which should be the case on the
clipv1, clipv2, clipplus. I have only enabled it for the clip plus
as thats the only device I have to test it on.

On clip+ the SSP clock is now turned off when screen is off

Change-Id: Ib5fd24697bfe4ac8b8ee017361e789e4a7910d21

1 files changed, 32 insertions, 0 deletions

diff --git a/firmware/target/arm/as3525/sansa-clipplus/lcd-clip-plus.c b/firmware/target/arm/as3525/sansa-clipplus/lcd-clip-plus.c
index c0b128a486..a50a9e5c80 100644
--- a/firmware/target/arm/as3525/sansa-clipplus/lcd-clip-plus.c
+++ b/firmware/target/arm/as3525/sansa-clipplus/lcd-clip-plus.c
@@ -64,6 +64,31 @@ void lcd_write_command(int byte)
         ;
 }
 
+void lcd_write_cmd_triplet(int cmd1, int cmd2, int cmd3)
+{
+#ifndef LCD_USE_FIFO_FOR_COMMANDS
+    lcd_write_command(cmd1);
+    lcd_write_command(cmd2);
+    lcd_write_command(cmd3);
+#else
+    /* combine writes to data register */
+    while(SSP_SR & (1<<4))  /* BSY flag */
+        ;
+    /* FIFO is empty at this point */
+
+    /* LCD command mode */
+    GPIOB_PIN(2) = 0;
+
+    /* !!makes assumption FIFO is at least (3) levels deep!! */
+    SSP_DATA = cmd1;
+    SSP_DATA = cmd2;
+    SSP_DATA = cmd3;
+
+    while(SSP_SR & (1<<4))  /* BSY flag */
+        ;
+#endif
+}
+
 void lcd_write_data(const fb_data* p_bytes, int count)
 {
     /* LCD data mode */
@@ -80,6 +105,13 @@ void lcd_write_data(const fb_data* p_bytes, int count)
 
 void lcd_enable_power(bool onoff)
 {
+#ifndef BOOTLOADER
+    if (onoff)
+        bitset32(&CGU_PERI, CGU_SSP_CLOCK_ENABLE);
+    else
+        bitclr32(&CGU_PERI, CGU_SSP_CLOCK_ENABLE);
+#else
     (void) onoff;
+#endif
 }