drm/sun4i: tcon: Support LVDS output on Allwinner A20

A20 SoC (found in Cubieboard 2 among others) requires different LVDS set
up procedure than A33. Timing controller (tcon) driver only implements
sun6i-style procedure, that doesn't work on A20 (sun7i).
Signed-off-by: Andrey Lebedev <andrey@lebedev.lt>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20200219180858.4806-6-andrey.lebedev@gmail.com

drivers/gpu/drm/sun4i/sun4i_tcon.c

@@ -114,6 +114,30 @@ static void sun4i_tcon_channel_set_status(struct sun4i_tcon *tcon, int channel,
 	}
 }
 
+static void sun4i_tcon_setup_lvds_phy(struct sun4i_tcon *tcon,
+				      const struct drm_encoder *encoder)
+{
+	regmap_write(tcon->regs, SUN4I_TCON0_LVDS_ANA0_REG,
+		     SUN4I_TCON0_LVDS_ANA0_CK_EN |
+		     SUN4I_TCON0_LVDS_ANA0_REG_V |
+		     SUN4I_TCON0_LVDS_ANA0_REG_C |
+		     SUN4I_TCON0_LVDS_ANA0_EN_MB |
+		     SUN4I_TCON0_LVDS_ANA0_PD |
+		     SUN4I_TCON0_LVDS_ANA0_DCHS);
+
+	udelay(2); /* delay at least 1200 ns */
+	regmap_update_bits(tcon->regs, SUN4I_TCON0_LVDS_ANA1_REG,
+			   SUN4I_TCON0_LVDS_ANA1_INIT,
+			   SUN4I_TCON0_LVDS_ANA1_INIT);
+	udelay(1); /* delay at least 120 ns */
+	regmap_update_bits(tcon->regs, SUN4I_TCON0_LVDS_ANA1_REG,
+			   SUN4I_TCON0_LVDS_ANA1_UPDATE,
+			   SUN4I_TCON0_LVDS_ANA1_UPDATE);
+	regmap_update_bits(tcon->regs, SUN4I_TCON0_LVDS_ANA0_REG,
+			   SUN4I_TCON0_LVDS_ANA0_EN_MB,
+			   SUN4I_TCON0_LVDS_ANA0_EN_MB);
+}
+
 static void sun6i_tcon_setup_lvds_phy(struct sun4i_tcon *tcon,
 				      const struct drm_encoder *encoder)
 {
@@ -1454,6 +1478,16 @@ static const struct sun4i_tcon_quirks sun6i_a31s_quirks = {
 	.dclk_min_div		= 1,
 };
 
+static const struct sun4i_tcon_quirks sun7i_a20_tcon0_quirks = {
+	.supports_lvds		= true,
+	.has_channel_0		= true,
+	.has_channel_1		= true,
+	.dclk_min_div		= 4,
+	/* Same display pipeline structure as A10 */
+	.set_mux		= sun4i_a10_tcon_set_mux,
+	.setup_lvds_phy		= sun4i_tcon_setup_lvds_phy,
+};
+
 static const struct sun4i_tcon_quirks sun7i_a20_quirks = {
 	.has_channel_0		= true,
 	.has_channel_1		= true,
@@ -1508,7 +1542,7 @@ const struct of_device_id sun4i_tcon_of_table[] = {
 	{ .compatible = "allwinner,sun6i-a31-tcon", .data = &sun6i_a31_quirks },
 	{ .compatible = "allwinner,sun6i-a31s-tcon", .data = &sun6i_a31s_quirks },
 	{ .compatible = "allwinner,sun7i-a20-tcon", .data = &sun7i_a20_quirks },
-	{ .compatible = "allwinner,sun7i-a20-tcon0", .data = &sun7i_a20_quirks },
+	{ .compatible = "allwinner,sun7i-a20-tcon0", .data = &sun7i_a20_tcon0_quirks },
 	{ .compatible = "allwinner,sun7i-a20-tcon1", .data = &sun7i_a20_quirks },
 	{ .compatible = "allwinner,sun8i-a23-tcon", .data = &sun8i_a33_quirks },
 	{ .compatible = "allwinner,sun8i-a33-tcon", .data = &sun8i_a33_quirks },

drivers/gpu/drm/sun4i/sun4i_tcon.h

@@ -193,6 +193,13 @@
 #define SUN4I_TCON_MUX_CTRL_REG			0x200
 
 #define SUN4I_TCON0_LVDS_ANA0_REG		0x220
+#define SUN4I_TCON0_LVDS_ANA0_DCHS			BIT(16)
+#define SUN4I_TCON0_LVDS_ANA0_PD			(BIT(20) | BIT(21))
+#define SUN4I_TCON0_LVDS_ANA0_EN_MB			BIT(22)
+#define SUN4I_TCON0_LVDS_ANA0_REG_C			(BIT(24) | BIT(25))
+#define SUN4I_TCON0_LVDS_ANA0_REG_V			(BIT(26) | BIT(27))
+#define SUN4I_TCON0_LVDS_ANA0_CK_EN			(BIT(29) | BIT(28))
+
 #define SUN6I_TCON0_LVDS_ANA0_EN_MB			BIT(31)
 #define SUN6I_TCON0_LVDS_ANA0_EN_LDO			BIT(30)
 #define SUN6I_TCON0_LVDS_ANA0_EN_DRVC			BIT(24)
@@ -201,6 +208,10 @@
 #define SUN6I_TCON0_LVDS_ANA0_V(x)			(((x) & 3) << 8)
 #define SUN6I_TCON0_LVDS_ANA0_PD(x)			(((x) & 3) << 4)
 
+#define SUN4I_TCON0_LVDS_ANA1_REG		0x224
+#define SUN4I_TCON0_LVDS_ANA1_INIT			(0x1f << 26 | 0x1f << 10)
+#define SUN4I_TCON0_LVDS_ANA1_UPDATE			(0x1f << 16 | 0x1f << 00)
+
 #define SUN4I_TCON1_FILL_CTL_REG		0x300
 #define SUN4I_TCON1_FILL_BEG0_REG		0x304
 #define SUN4I_TCON1_FILL_END0_REG		0x308