staging/fbtft: Add support for display variants

Display variants are intended as a replacement for the now-deleted
fbtft_device drivers. Drivers can register additional compatible
strings with a custom callback that can make the required changes
to the fbtft_display structure.

Start the ball rolling by adding adafruit18, adafruit18_green and
sainsmart18 displays.

Signed-off-by: Phil Elwell <phil@raspberrypi.com>

drivers/staging/fbtft/fb_st7735r.c

@@ -16,6 +16,10 @@
 #define DEFAULT_GAMMA   "0F 1A 0F 18 2F 28 20 22 1F 1B 23 37 00 07 02 10\n" \
 			"0F 1B 0F 17 33 2C 29 2E 30 30 39 3F 00 07 03 10"
 
+#define ADAFRUIT18_GAMMA \
+			"02 1c 07 12 37 32 29 2d 29 25 2B 39 00 01 03 10\n" \
+			"03 1d 07 06 2E 2C 29 2D 2E 2E 37 3F 00 00 02 10"
+
 static const s16 default_init_sequence[] = {
 	-1, MIPI_DCS_SOFT_RESET,
 	-2, 150,                               /* delay */
@@ -94,6 +98,14 @@ static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
 	write_reg(par, MIPI_DCS_WRITE_MEMORY_START);
 }
 
+static void adafruit18_green_tab_set_addr_win(struct fbtft_par *par,
+					      int xs, int ys, int xe, int ye)
+{
+	write_reg(par, 0x2A, 0, xs + 2, 0, xe + 2);
+	write_reg(par, 0x2B, 0, ys + 1, 0, ye + 1);
+	write_reg(par, 0x2C);
+}
+
 #define MY BIT(7)
 #define MX BIT(6)
 #define MV BIT(5)
@@ -174,12 +186,36 @@ static struct fbtft_display display = {
 	},
 };
 
-FBTFT_REGISTER_DRIVER(DRVNAME, "sitronix,st7735r", &display);
+int variant_adafruit18(struct fbtft_display *display)
+{
+	display->gamma = ADAFRUIT18_GAMMA;
+	return 0;
+}
+
+int variant_adafruit18_green(struct fbtft_display *display)
+{
+	display->gamma = ADAFRUIT18_GAMMA;
+	display->fbtftops.set_addr_win = adafruit18_green_tab_set_addr_win;
+	return 0;
+}
+
+FBTFT_REGISTER_DRIVER_START(&display)
+FBTFT_COMPATIBLE("sitronix,st7735r")
+FBTFT_COMPATIBLE("fbtft,sainsmart18")
+FBTFT_VARIANT_COMPATIBLE("fbtft,adafruit18", variant_adafruit18)
+FBTFT_VARIANT_COMPATIBLE("fbtft,adafruit18_green", variant_adafruit18_green)
+FBTFT_REGISTER_DRIVER_END(DRVNAME, &display);
 
 MODULE_ALIAS("spi:" DRVNAME);
 MODULE_ALIAS("platform:" DRVNAME);
 MODULE_ALIAS("spi:st7735r");
 MODULE_ALIAS("platform:st7735r");
+MODULE_ALIAS("spi:sainsmart18");
+MODULE_ALIAS("platform:sainsmart");
+MODULE_ALIAS("spi:adafruit18");
+MODULE_ALIAS("platform:adafruit18");
+MODULE_ALIAS("spi:adafruit18_green");
+MODULE_ALIAS("platform:adafruit18_green");
 
 MODULE_DESCRIPTION("FB driver for the ST7735R LCD Controller");
 MODULE_AUTHOR("Noralf Tronnes");

drivers/staging/fbtft/fbtft-core.c

@@ -24,6 +24,8 @@
 #include <linux/platform_device.h>
 #include <linux/property.h>
 #include <linux/spinlock.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
 
 #include <video/mipi_display.h>
 
@@ -1199,6 +1201,7 @@ static struct fbtft_platform_data *fbtft_properties_read(struct device *dev)
  * @display: Display properties
  * @sdev: SPI device
  * @pdev: Platform device
+ * @dt_ids: Compatible string table
  *
  * Allocates, initializes and registers a framebuffer
  *
@@ -1208,12 +1211,15 @@ static struct fbtft_platform_data *fbtft_properties_read(struct device *dev)
  */
 int fbtft_probe_common(struct fbtft_display *display,
 		       struct spi_device *sdev,
-		       struct platform_device *pdev)
+		       struct platform_device *pdev,
+		       const struct of_device_id *dt_ids)
 {
 	struct device *dev;
 	struct fb_info *info;
 	struct fbtft_par *par;
 	struct fbtft_platform_data *pdata;
+	const struct of_device_id *match;
+	int (*variant)(struct fbtft_display *);
 	int ret;
 
 	if (sdev)
@@ -1229,6 +1235,14 @@ int fbtft_probe_common(struct fbtft_display *display,
 		pdata = fbtft_properties_read(dev);
 		if (IS_ERR(pdata))
 			return PTR_ERR(pdata);
+		match = of_match_device(dt_ids, dev);
+		if (match && match->data) {
+			/* apply the variant */
+			variant = match->data;
+			ret = (*variant)(display);
+			if (ret)
+				return ret;
+		}
 	}
 
 	info = fbtft_framebuffer_alloc(display, dev, pdata);

drivers/staging/fbtft/fbtft.h

@@ -251,7 +251,8 @@ void fbtft_register_backlight(struct fbtft_par *par);
 void fbtft_unregister_backlight(struct fbtft_par *par);
 int fbtft_init_display(struct fbtft_par *par);
 int fbtft_probe_common(struct fbtft_display *display, struct spi_device *sdev,
-		       struct platform_device *pdev);
+		       struct platform_device *pdev,
+		       const struct of_device_id *dt_ids);
 int fbtft_remove_common(struct device *dev, struct fb_info *info);
 
 /* fbtft-io.c */
@@ -272,11 +273,13 @@ void fbtft_write_reg8_bus9(struct fbtft_par *par, int len, ...);
 void fbtft_write_reg16_bus8(struct fbtft_par *par, int len, ...);
 void fbtft_write_reg16_bus16(struct fbtft_par *par, int len, ...);
 
-#define FBTFT_REGISTER_DRIVER(_name, _compatible, _display)                \
+#define FBTFT_REGISTER_DRIVER_START(_display)                              \
+									   \
+static const struct of_device_id dt_ids[];                                 \
 									   \
 static int fbtft_driver_probe_spi(struct spi_device *spi)                  \
 {                                                                          \
-	return fbtft_probe_common(_display, spi, NULL);                    \
+	return fbtft_probe_common(_display, spi, NULL, dt_ids);	           \
 }                                                                          \
 									   \
 static int fbtft_driver_remove_spi(struct spi_device *spi)                 \
@@ -288,7 +291,7 @@ static int fbtft_driver_remove_spi(struct spi_device *spi)                 \
 									   \
 static int fbtft_driver_probe_pdev(struct platform_device *pdev)           \
 {                                                                          \
-	return fbtft_probe_common(_display, NULL, pdev);                   \
+	return fbtft_probe_common(_display, NULL, pdev, dt_ids);           \
 }                                                                          \
 									   \
 static int fbtft_driver_remove_pdev(struct platform_device *pdev)          \
@@ -298,8 +301,16 @@ static int fbtft_driver_remove_pdev(struct platform_device *pdev)          \
 	return fbtft_remove_common(&pdev->dev, info);                      \
 }                                                                          \
 									   \
-static const struct of_device_id dt_ids[] = {                              \
+static const struct of_device_id dt_ids[] = {
-	{ .compatible = _compatible },                                     \
+
+#define FBTFT_COMPATIBLE(_compatible)                                      \
+	{ .compatible = _compatible },
+
+#define FBTFT_VARIANT_COMPATIBLE(_compatible, _variant)                    \
+	{ .compatible = _compatible, .data = _variant },
+
+#define FBTFT_REGISTER_DRIVER_END(_name, _display)                         \
+									   \
 	{},                                                                \
 };                                                                         \
 									   \
@@ -344,6 +355,11 @@ static void __exit fbtft_driver_module_exit(void)                          \
 module_init(fbtft_driver_module_init);                                     \
 module_exit(fbtft_driver_module_exit);
 
+#define FBTFT_REGISTER_DRIVER(_name, _compatible, _display)                \
+	FBTFT_REGISTER_DRIVER_START(_display)                              \
+	FBTFT_COMPATIBLE(_compatible)                                      \
+	FBTFT_REGISTER_DRIVER_END(_name, _display)
+
 /* Debug macros */
 
 /* shorthand debug levels */