staging: fbtft: add helper fbtft_write_buf_dc

Factor out setting DC GPIO and writing buffer content to helper
fbtft_write_buf_dc.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/fbtft/fbtft-core.c

@@ -43,6 +43,21 @@ static unsigned long debug;
 module_param(debug, ulong, 0000);
 MODULE_PARM_DESC(debug, "override device debug level");
 
+int fbtft_write_buf_dc(struct fbtft_par *par, void *buf, size_t len, int dc)
+{
+	int ret;
+
+	if (gpio_is_valid(par->gpio.dc))
+		gpio_set_value(par->gpio.dc, dc);
+
+	ret = par->fbtftops.write(par, buf, len);
+	if (ret < 0)
+		dev_err(par->info->device,
+			"write() failed and returned %d\n", ret);
+	return ret;
+}
+EXPORT_SYMBOL(fbtft_write_buf_dc);
+
 void fbtft_dbg_hex(const struct device *dev, int groupsize,
 		   void *buf, size_t len, const char *fmt, ...)
 {

drivers/staging/fbtft/fbtft.h

@@ -248,6 +248,7 @@ struct fbtft_par {
 	par->fbtftops.write_register(par, NUMARGS(__VA_ARGS__), __VA_ARGS__)
 
 /* fbtft-core.c */
+int fbtft_write_buf_dc(struct fbtft_par *par, void *buf, size_t len, int dc);
 void fbtft_dbg_hex(const struct device *dev, int groupsize,
 		   void *buf, size_t len, const char *fmt, ...);
 struct fb_info *fbtft_framebuffer_alloc(struct fbtft_display *display,