staging: fbtft: fb_ssd1306: Support smaller screen sizes

There is 64x48 display exists. In order to support that set multiplexer
to 48 pixels and window address to proper position in the graphic display
data RAM.

Acked-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/fbtft/fb_ssd1306.c b/drivers/staging/fbtft/fb_ssd1306.c
index 80fc57029fee7f256851e2c53b024ae551835f9d..bede2d5a55717ff322e3e56a18aff3da53ac59fa 100644 (file)
--- a/drivers/staging/fbtft/fb_ssd1306.c
+++ b/drivers/staging/fbtft/fb_ssd1306.c
@@ -62,6 +62,8 @@ static int init_display(struct fbtft_par *par)
        write_reg(par, 0xA8);
        if (par->info->var.yres == 64)
                write_reg(par, 0x3F);
+       else if (par->info->var.yres == 48)
+               write_reg(par, 0x2F);
        else
                write_reg(par, 0x1F);
 
@@ -95,6 +97,9 @@ static int init_display(struct fbtft_par *par)
        if (par->info->var.yres == 64)
                /* A[4]=1b, Alternative COM pin configuration */
                write_reg(par, 0x12);
+       else if (par->info->var.yres == 48)
+               /* A[4]=1b, Alternative COM pin configuration */
+               write_reg(par, 0x12);
        else
                /* A[4]=0b, Sequential COM pin configuration */
                write_reg(par, 0x02);
@@ -124,6 +129,19 @@ static int init_display(struct fbtft_par *par)
        return 0;
 }
 
+static void set_addr_win_64x48(struct fbtft_par *par)
+{
+       /* Set Column Address */
+       write_reg(par, 0x21);
+       write_reg(par, 0x20);
+       write_reg(par, 0x5F);
+
+       /* Set Page Address */
+       write_reg(par, 0x22);
+       write_reg(par, 0x0);
+       write_reg(par, 0x5);
+}
+
 static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
 {
        /* Set Lower Column Start Address for Page Addressing Mode */
@@ -132,6 +150,9 @@ static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
        write_reg(par, 0x10 | 0x0);
        /* Set Display Start Line */
        write_reg(par, 0x40 | 0x0);
+
+       if (par->info->var.xres == 64 && par->info->var.yres == 48)
+               set_addr_win_64x48(par);
 }
 
 static int blank(struct fbtft_par *par, bool on)