[PATCH v2] staging: fbtft: fb_st7789v: support setting offset

[Yuguo Pei <purofle@gmail.com>]

Some screen sizes using st7789v chips are different from 240x320,
and offsets need to be set to display all images properly.

For those who use screens with offset, they only need to modify the values
of size and offset, and do not need to a new set_addr_win function.

Signed-off-by: Yuguo Pei <purofle@gmail.com>
---
v2: modify Signed-off-by, fix explanation of changes

 drivers/staging/fbtft/fb_st7789v.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/staging/fbtft/fb_st7789v.c b/drivers/staging/fbtft/fb_st7789v.c
index 861a154144e6..d47ab4262374 100644
--- a/drivers/staging/fbtft/fb_st7789v.c
+++ b/drivers/staging/fbtft/fb_st7789v.c
@@ -30,6 +30,12 @@
 
 #define HSD20_IPS 1
 
+#define WIDTH 240
+#define HEIGHT 320
+
+#define LEFT_OFFSET 0
+#define TOP_OFFSET 0
+
 /**
  * enum st7789v_command - ST7789V display controller commands
  *
@@ -349,6 +355,21 @@ static int set_gamma(struct fbtft_par *par, u32 *curves)
 	return 0;
 }
 
+static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
+{
+	unsigned int x = xs + TOP_OFFSET, y = xe + TOP_OFFSET;
+
+	write_reg(par, MIPI_DCS_SET_COLUMN_ADDRESS, (x >> 8) & 0xFF, xs & 0xFF,
+		  (y >> 8) & 0xFF, xe & 0xFF);
+
+	x = ys + LEFT_OFFSET, y = ye + LEFT_OFFSET;
+
+	write_reg(par, MIPI_DCS_SET_PAGE_ADDRESS, (x >> 8) & 0xFF, ys & 0xFF,
+		  (y >> 8) & 0xFF, ye & 0xFF);
+
+	write_reg(par, MIPI_DCS_WRITE_MEMORY_START);
+}
+
 /**
  * blank() - blank the display
  *
@@ -379,6 +400,7 @@ static struct fbtft_display display = {
 		.set_var = set_var,
 		.set_gamma = set_gamma,
 		.blank = blank,
+		.set_addr_win = set_addr_win,
 	},
 };
 
-- 
2.44.0