Add support for Mayqueen Pixpaper e-ink panel

Introduce a DRM driver for the Mayqueen Pixpaper e-ink display panel, which is controlled via SPI. The driver supports a 122x250 resolution display with XRGB8888 format.

Also, add a MAINTAINERS entry for the Pixpaper driver.

Signed-off-by LiangCheng Wang <[email protected]>

---
  MAINTAINERS                          |   7 +
  drivers/gpu/drm/tiny/Kconfig         |  15 +
  drivers/gpu/drm/tiny/Makefile        |   1 +
  drivers/gpu/drm/tiny/pixpaper-regs.h | 428 +++++++++++++++++++

  drivers/gpu/drm/tiny/pixpaper.c      | 789 +++++++++++++++++++++++++++++++++++
  5 files changed, 1240 insertions(+)

MAINTAINERS +0 -0

index 1b57dd4fcf0154cdea9f83bccf5be3325f87d993..fe25537276c25eabfb38253c0e1352ed0d1ebb86 100644

MAINTAINERS +1 -0

+
  DRM DRIVER FOR QEMU'S CIRRUS DEVICE
  M:	Dave Airlie <[email protected]>
  M:	Gerd Hoffmann <[email protected]>

drivers/gpu/drm/tiny/Kconfig +15 -0

index 06e54694a7f2fe1649e1886f039926b24f698e0d..94a5bf61a115929640022128e20c723ab7c0e735 100644
@@ -82,6 +82,21 @@ config DRM_PANEL_MIPI_DBI
  	  https://github.com/notro/panel-mipi-dbi/wiki.
  	  To compile this driver as a module, choose M here.
 
+config DRM_PIXPAPER
+        tristate "DRM support for PIXPAPER display panels"
+        depends on DRM && SPI
+        select DRM_CLIENT_SELECTION
+        select DRM_GEM_DMA_HELPER
+        select DRM_KMS_HELPER
+        help
+	  DRM driver for the Mayqueen Pixpaper e-ink display panel.
+
+	  This driver supports small e-paper displays connected over SPI,
+	  with a resolution of 122x250 and XRGB8888 framebuffer format.
+	  It is intended for low-power embedded applications.
+
+	  If M is selected, the module will be built as pixpaper.ko.
+
  config TINYDRM_HX8357D
  	tristate "DRM support for HX8357D display panels"
  	depends on DRM && SPI

drivers/gpu/drm/tiny/Makefile +1 -0

index 4a9ff61ec25420e2c0a648c04eaab7ca25dd5407..48d30bf6152f979404ac1004174587823a30109e 100644
@@ -6,6 +6,7 @@ obj-$(CONFIG_DRM_BOCHS)			+= bochs.o
  obj-$(CONFIG_DRM_CIRRUS_QEMU)		+= cirrus-qemu.o
  obj-$(CONFIG_DRM_GM12U320)		+= gm12u320.o
  obj-$(CONFIG_DRM_PANEL_MIPI_DBI)	+= panel-mipi-dbi.o
+obj-$(CONFIG_DRM_PIXPAPER)              += pixpaper.o
  obj-$(CONFIG_TINYDRM_HX8357D)		+= hx8357d.o
  obj-$(CONFIG_TINYDRM_ILI9163)		+= ili9163.o
  obj-$(CONFIG_TINYDRM_ILI9225)		+= ili9225.o

drivers/gpu/drm/tiny/pixpaper-regs.h new file +428 -0

new file mode 100644
index 0000000000000000000000000000000000000000..d6ea0531ded6879c13de334345cef7add210b931
@@ -0,0 +1,428 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Register definitions for PIXPAPER e-ink panel
+ *
+ * Author: LiangCheng Wang <[email protected]>
+ */
+
+#ifndef __PIXPAPER_REGS_H__
+#define __PIXPAPER_REGS_H__
+
+/*
+ * Note on Undocumented Commands/Registers:
+ *
+ * Several commands and register parameters defined in this header are not
+ * documented in the datasheet. Their values and usage have been derived
+ * through analysis of existing userspace example programs.
+ *
+ * These 'unknown' definitions are crucial for the proper initialization
+ * and stable operation of the panel. Modifying these values without
+ * thorough understanding may lead to display anomalies, panel damage,
+ * or unexpected behavior.
+ */
+
+/* Command definitions */
+#define PIXPAPER_CMD_PANEL_SETTING 0x00	/* R00H: Panel settings */
+#define PIXPAPER_CMD_POWER_SETTING 0x01	/* R01H: Power settings */
+#define PIXPAPER_CMD_POWER_OFF 0x02		/* R02H: Power off */
+#define PIXPAPER_CMD_POWER_OFF_SEQUENCE 0x03	/* R03H: Power off sequence */
+#define PIXPAPER_CMD_POWER_ON 0x04		/* R04H: Power on */
+#define PIXPAPER_CMD_BOOSTER_SOFT_START 0x06	/* R06H: Booster soft start */
+#define PIXPAPER_CMD_DEEP_SLEEP 0x07		/* R07H: Deep sleep */
+#define PIXPAPER_CMD_DATA_START_TRANSMISSION 0x10
+/* R10H: Data transmission start */
+#define PIXPAPER_CMD_DISPLAY_REFRESH 0x12	/* R12H: Display refresh */
+#define PIXPAPER_CMD_PLL_CONTROL 0x30		/* R30H: PLL control */
+#define PIXPAPER_CMD_TEMP_SENSOR_CALIB 0x41
+/* R41H: Temperature sensor calibration */
+#define PIXPAPER_CMD_UNKNOWN_4D 0x4D		/* R4DH: Unknown command */
+#define PIXPAPER_CMD_VCOM_INTERVAL 0x50	/* R50H: VCOM interval */
+#define PIXPAPER_CMD_UNKNOWN_60 0x60		/* R60H: Unknown command */
+#define PIXPAPER_CMD_RESOLUTION_SETTING 0x61	/* R61H: Resolution settings */
+#define PIXPAPER_CMD_GATE_SOURCE_START 0x65	/* R65H: Gate/source start */
+#define PIXPAPER_CMD_UNKNOWN_B4 0xB4		/* RB4H: Unknown command */
+#define PIXPAPER_CMD_UNKNOWN_B5 0xB5		/* RB5H: Unknown command */
+#define PIXPAPER_CMD_UNKNOWN_E0 0xE0		/* RE0H: Unknown command */
+#define PIXPAPER_CMD_POWER_SAVING 0xE3		/* RE3H: Power saving */
+#define PIXPAPER_CMD_UNKNOWN_E7 0xE7		/* RE7H: Unknown command */
+#define PIXPAPER_CMD_UNKNOWN_E9 0xE9		/* RE9H: Unknown command */
+
+/* R00H PSR - First Parameter */
+#define PIXPAPER_PSR_RST_N BIT(0)
+/* Bit 0: RST_N, 1=no effect (default), 0=reset with booster OFF */
+#define PIXPAPER_PSR_SHD_N BIT(1)
+/* Bit 1: SHD_N, 1=booster ON (default), 0=booster OFF */
+#define PIXPAPER_PSR_SHL BIT(2)
+/* Bit 2: SHL, 1=shift right (default), 0=shift left */
+#define PIXPAPER_PSR_UD BIT(3)
+/* Bit 3: UD, 1=scan up (default), 0=scan down */
+#define PIXPAPER_PSR_PST_MODE BIT(5)
+/* Bit 5: PST_MODE, 0=frame scanning (default), 1=external */
+#define PIXPAPER_PSR_RES_MASK (3 << 6)
+/* Bits 7-6: RES[1:0], resolution setting */
+#define PIXPAPER_PSR_RES_176x296 (0x0 << 6)	/* 00: 176x296 */
+#define PIXPAPER_PSR_RES_128x296 (0x1 << 6)	/* 01: 128x296 */
+#define PIXPAPER_PSR_RES_128x250 (0x2 << 6)	/* 10: 128x250 */
+#define PIXPAPER_PSR_RES_112x204 (0x3 << 6)	/* 11: 112x204 */
+#define PIXPAPER_PSR_CONFIG                                           \
+	(PIXPAPER_PSR_RST_N | PIXPAPER_PSR_SHD_N | PIXPAPER_PSR_SHL | \
+	 PIXPAPER_PSR_UD)
+/* 0x0F: Default settings, resolution set by R61H */
+
+/* R00H PSR - Second Parameter */
+#define PIXPAPER_PSR2_VC_LUTZ \
+	(1 << 0) /* Bit 0: VC_LUTZ, 1=VCOM float after refresh (default), 0=no effect */
+#define PIXPAPER_PSR2_NORG \
+	(1 << 1) /* Bit 1: NORG, 1=VCOM to GND before power off, 0=no effect (default) */
+#define PIXPAPER_PSR2_TIEG \
+	(1 << 2) /* Bit 2: TIEG, 1=VGN to GND on power off, 0=no effect (default) */
+#define PIXPAPER_PSR2_TS_AUTO \
+	(1 << 3) /* Bit 3: TS_AUTO, 1=sensor on RST_N low to high (default), 0=on booster */
+#define PIXPAPER_PSR2_VCMZ \
+	(1 << 4) /* Bit 4: VCMZ, 1=VCOM always floating, 0=no effect (default) */
+#define PIXPAPER_PSR2_FOPT \
+	(1 << 5) /* Bit 5: FOPT, 0=scan 1 frame (default), 1=no scan, HiZ */
+#define PIXPAPER_PSR_CONFIG2     \
+	(PIXPAPER_PSR2_VC_LUTZ | \
+	 PIXPAPER_PSR2_TS_AUTO) /* 0x09: Default VCOM and temp sensor settings */
+
+/* R01H PWR - Power Setting Register */
+/* First Parameter */
+#define PIXPAPER_PWR_VDG_EN \
+	(1 << 0) /* Bit 0: VDG_EN, 1=internal DCDC for VGP/VGN (default), 0=external */
+#define PIXPAPER_PWR_VDS_EN \
+	(1 << 1) /* Bit 1: VDS_EN, 1=internal regulator for VSP/VSN (default), 0=external */
+#define PIXPAPER_PWR_VSC_EN \
+	(1 << 2) /* Bit 2: VSC_EN, 1=internal regulator for VSPL (default), 0=external */
+#define PIXPAPER_PWR_V_MODE \
+	(1 << 3) /* Bit 3: V_MODE, 0=Mode0 (default), 1=Mode1 */
+#define PIXPAPER_PWR_CONFIG1                         \
+	(PIXPAPER_PWR_VDG_EN | PIXPAPER_PWR_VDS_EN | \
+	 PIXPAPER_PWR_VSC_EN) /* 0x07: Internal power for VGP/VGN, VSP/VSN, VSPL */
+
+/* Second Parameter */
+#define PIXPAPER_PWR_VGPN_MASK \
+	(3 << 0) /* Bits 1-0: VGPN, VGP/VGN voltage levels */
+#define PIXPAPER_PWR_VGPN_20V (0x0 << 0) /* 00: VGP=20V, VGN=-20V (default) */
+#define PIXPAPER_PWR_VGPN_17V (0x1 << 0) /* 01: VGP=17V, VGN=-17V */
+#define PIXPAPER_PWR_VGPN_15V (0x2 << 0) /* 10: VGP=15V, VGN=-15V */
+#define PIXPAPER_PWR_VGPN_10V (0x3 << 0) /* 11: VGP=10V, VGN=-10V */
+#define PIXPAPER_PWR_CONFIG2 PIXPAPER_PWR_VGPN_20V /* 0x00: VGP=20V, VGN=-20V */
+
+/* Third, Fourth, Sixth Parameters (VSP_1, VSPL_0, VSPL_1) */
+#define PIXPAPER_PWR_VSP_8_2V 0x22 /* VSP_1/VSPL_1: 8.2V (34 decimal) */
+#define PIXPAPER_PWR_VSPL_15V 0x78 /* VSPL_0: 15V (120 decimal) */
+
+/* Fifth Parameter (VSN_1) */
+#define PIXPAPER_PWR_VSN_4V 0x0A /* VSN_1: -4V (10 decimal) */
+
+/* R03H PFS - Power Off Sequence Setting Register */
+/* First Parameter */
+#define PIXPAPER_PFS_T_VDS_OFF_MASK \
+	(3 << 0) /* Bits 1-0: T_VDS_OFF, VSP/VSN power-off sequence */
+#define PIXPAPER_PFS_T_VDS_OFF_20MS (0x0 << 0) /* 00: 20 ms (default) */
+#define PIXPAPER_PFS_T_VDS_OFF_40MS (0x1 << 0) /* 01: 40 ms */
+#define PIXPAPER_PFS_T_VDS_OFF_60MS (0x2 << 0) /* 10: 60 ms */
+#define PIXPAPER_PFS_T_VDS_OFF_80MS (0x3 << 0) /* 11: 80 ms */
+#define PIXPAPER_PFS_T_VDPG_OFF_MASK \
+	(3 << 4) /* Bits 5-4: T_VDPG_OFF, VGP/VGN power-off sequence */
+#define PIXPAPER_PFS_T_VDPG_OFF_20MS (0x0 << 4) /* 00: 20 ms (default) */
+#define PIXPAPER_PFS_T_VDPG_OFF_40MS (0x1 << 4) /* 01: 40 ms */
+#define PIXPAPER_PFS_T_VDPG_OFF_60MS (0x2 << 4) /* 10: 60 ms */
+#define PIXPAPER_PFS_T_VDPG_OFF_80MS (0x3 << 4) /* 11: 80 ms */
+#define PIXPAPER_PFS_CONFIG1           \
+	(PIXPAPER_PFS_T_VDS_OFF_20MS | \
+	 PIXPAPER_PFS_T_VDPG_OFF_20MS) /* 0x10: Default 20 ms for VSP/VSN and VGP/VGN */
+
+/* Second Parameter */
+#define PIXPAPER_PFS_VGP_EXT_MASK \
+	(0xF << 0) /* Bits 3-0: VGP_EXT, VGP extension time */
+#define PIXPAPER_PFS_VGP_EXT_0MS (0x0 << 0) /* 0000: 0 ms */
+#define PIXPAPER_PFS_VGP_EXT_500MS (0x1 << 0) /* 0001: 500 ms */
+#define PIXPAPER_PFS_VGP_EXT_1000MS (0x2 << 0) /* 0010: 1000 ms */
+#define PIXPAPER_PFS_VGP_EXT_1500MS (0x3 << 0) /* 0011: 1500 ms */
+#define PIXPAPER_PFS_VGP_EXT_2000MS (0x4 << 0) /* 0100: 2000 ms (default) */
+#define PIXPAPER_PFS_VGP_EXT_2500MS (0x5 << 0) /* 0101: 2500 ms */
+#define PIXPAPER_PFS_VGP_EXT_3000MS (0x6 << 0) /* 0110: 3000 ms */
+#define PIXPAPER_PFS_VGP_EXT_3500MS (0x7 << 0) /* 0111: 3500 ms */
+#define PIXPAPER_PFS_VGP_EXT_4000MS (0x8 << 0) /* 1000: 4000 ms */
+#define PIXPAPER_PFS_VGP_EXT_4500MS (0x9 << 0) /* 1001: 4500 ms */
+#define PIXPAPER_PFS_VGP_EXT_5000MS (0xA << 0) /* 1010: 5000 ms */
+#define PIXPAPER_PFS_VGP_EXT_5500MS (0xB << 0) /* 1011: 5500 ms */
+#define PIXPAPER_PFS_VGP_EXT_6000MS (0xC << 0) /* 1100: 6000 ms */
+#define PIXPAPER_PFS_VGP_EXT_6500MS (0xD << 0) /* 1101: 6500 ms */
+#define PIXPAPER_PFS_VGP_LEN_MASK \
+	(0xF << 4) /* Bits 7-4: VGP_LEN, VGP at 10V during power-off */
+#define PIXPAPER_PFS_VGP_LEN_0MS (0x0 << 4) /* 0000: 0 ms */
+#define PIXPAPER_PFS_VGP_LEN_500MS (0x1 << 4) /* 0001: 500 ms */
+#define PIXPAPER_PFS_VGP_LEN_1000MS (0x2 << 4) /* 0010: 1000 ms */
+#define PIXPAPER_PFS_VGP_LEN_1500MS (0x3 << 4) /* 0011: 1500 ms */
+#define PIXPAPER_PFS_VGP_LEN_2000MS (0x4 << 4) /* 0100: 2000 ms */
+#define PIXPAPER_PFS_VGP_LEN_2500MS (0x5 << 4) /* 0101: 2500 ms (default) */
+#define PIXPAPER_PFS_VGP_LEN_3000MS (0x6 << 4) /* 0110: 3000 ms */
+#define PIXPAPER_PFS_VGP_LEN_3500MS (0x7 << 4) /* 0111: 3500 ms */
+#define PIXPAPER_PFS_VGP_LEN_4000MS (0x8 << 4) /* 1000: 4000 ms */
+#define PIXPAPER_PFS_VGP_LEN_4500MS (0x9 << 4) /* 1001: 4500 ms */
+#define PIXPAPER_PFS_VGP_LEN_5000MS (0xA << 4) /* 1010: 5000 ms */
+#define PIXPAPER_PFS_VGP_LEN_5500MS (0xB << 4) /* 1011: 5500 ms */
+#define PIXPAPER_PFS_VGP_LEN_6000MS (0xC << 4) /* 1100: 6000 ms */
+#define PIXPAPER_PFS_VGP_LEN_6500MS (0xD << 4) /* 1101: 6500 ms */
+#define PIXPAPER_PFS_CONFIG2           \
+	(PIXPAPER_PFS_VGP_EXT_1000MS | \
+	 PIXPAPER_PFS_VGP_LEN_2500MS) /* 0x54: VGP extension 1000 ms, VGP at 10V for 2500 ms */
+
+/* Third Parameter */
+#define PIXPAPER_PFS_XON_LEN_MASK \
+	(0xF << 0) /* Bits 3-0: XON_LEN, XON enable time */
+#define PIXPAPER_PFS_XON_LEN_0MS (0x0 << 0) /* 0000: 0 ms */
+#define PIXPAPER_PFS_XON_LEN_500MS (0x1 << 0) /* 0001: 500 ms */
+#define PIXPAPER_PFS_XON_LEN_1000MS (0x2 << 0) /* 0010: 1000 ms */
+#define PIXPAPER_PFS_XON_LEN_1500MS (0x3 << 0) /* 0011: 1500 ms */
+#define PIXPAPER_PFS_XON_LEN_2000MS (0x4 << 0) /* 0100: 2000 ms (default) */
+#define PIXPAPER_PFS_XON_LEN_2500MS (0x5 << 0) /* 0101: 2500 ms */
+#define PIXPAPER_PFS_XON_LEN_3000MS (0x6 << 0) /* 0110: 3000 ms */
+#define PIXPAPER_PFS_XON_LEN_3500MS (0x7 << 0) /* 0111: 3500 ms */
+#define PIXPAPER_PFS_XON_LEN_4000MS (0x8 << 0) /* 1000: 4000 ms */
+#define PIXPAPER_PFS_XON_LEN_4500MS (0x9 << 0) /* 1001: 4500 ms */
+#define PIXPAPER_PFS_XON_LEN_5000MS (0xA << 0) /* 1010: 5000 ms */
+#define PIXPAPER_PFS_XON_LEN_5500MS (0xB << 0) /* 1011: 5500 ms */
+#define PIXPAPER_PFS_XON_LEN_6000MS (0xC << 0) /* 1100: 6000 ms */
+#define PIXPAPER_PFS_XON_DLY_MASK \
+	(0xF << 4) /* Bits 7-4: XON_DLY, XON delay time */
+#define PIXPAPER_PFS_XON_DLY_0MS (0x0 << 4) /* 0000: 0 ms */
+#define PIXPAPER_PFS_XON_DLY_500MS (0x1 << 4) /* 0001: 500 ms */
+#define PIXPAPER_PFS_XON_DLY_1000MS (0x2 << 4) /* 0010: 1000 ms */
+#define PIXPAPER_PFS_XON_DLY_1500MS (0x3 << 4) /* 0011: 1500 ms */
+#define PIXPAPER_PFS_XON_DLY_2000MS (0x4 << 4) /* 0100: 2000 ms (default) */
+#define PIXPAPER_PFS_XON_DLY_2500MS (0x5 << 4) /* 0101: 2500 ms */
+#define PIXPAPER_PFS_XON_DLY_3000MS (0x6 << 4) /* 0110: 3000 ms */
+#define PIXPAPER_PFS_XON_DLY_3500MS (0x7 << 4) /* 0111: 3500 ms */
+#define PIXPAPER_PFS_XON_DLY_4000MS (0x8 << 4) /* 1000: 4000 ms */
+#define PIXPAPER_PFS_XON_DLY_4500MS (0x9 << 4) /* 1001: 4500 ms */
+#define PIXPAPER_PFS_XON_DLY_5000MS (0xA << 4) /* 1010: 5000 ms */
+#define PIXPAPER_PFS_XON_DLY_5500MS (0xB << 4) /* 1011: 5500 ms */
+#define PIXPAPER_PFS_XON_DLY_6000MS (0xC << 4) /* 1100: 6000 ms */
+#define PIXPAPER_PFS_CONFIG3           \
+	(PIXPAPER_PFS_XON_LEN_2000MS | \
+	 PIXPAPER_PFS_XON_DLY_2000MS) /* 0x44: XON enable and delay at 2000 ms */
+
+/* R06H BTST - Booster Soft Start Command */
+/* First Parameter */
+#define PIXPAPER_BTST_PHA_SFT_MASK \
+	(3 << 0) /* Bits 1-0: PHA_SFT, soft start period for phase A */
+#define PIXPAPER_BTST_PHA_SFT_10MS (0x0 << 0) /* 00: 10 ms (default) */
+#define PIXPAPER_BTST_PHA_SFT_20MS (0x1 << 0) /* 01: 20 ms */
+#define PIXPAPER_BTST_PHA_SFT_30MS (0x2 << 0) /* 10: 30 ms */
+#define PIXPAPER_BTST_PHA_SFT_40MS (0x3 << 0) /* 11: 40 ms */
+#define PIXPAPER_BTST_PHB_SFT_MASK \
+	(3 << 2) /* Bits 3-2: PHB_SFT, soft start period for phase B */
+#define PIXPAPER_BTST_PHB_SFT_10MS (0x0 << 2) /* 00: 10 ms (default) */
+#define PIXPAPER_BTST_PHB_SFT_20MS (0x1 << 2) /* 01: 20 ms */
+#define PIXPAPER_BTST_PHB_SFT_30MS (0x2 << 2) /* 10: 30 ms */
+#define PIXPAPER_BTST_PHB_SFT_40MS (0x3 << 2) /* 11: 40 ms */
+#define PIXPAPER_BTST_CONFIG1         \
+	(PIXPAPER_BTST_PHA_SFT_40MS | \
+	 PIXPAPER_BTST_PHB_SFT_40MS) /* 0x0F: 40 ms for phase A and B */
+
+/* Second to Seventh Parameters (Driving Strength or Minimum OFF Time) */
+#define PIXPAPER_BTST_CONFIG2 0x0A /* Strength11 */
+#define PIXPAPER_BTST_CONFIG3 0x2F /* Period48 */
+#define PIXPAPER_BTST_CONFIG4 0x25 /* Strength38 */
+#define PIXPAPER_BTST_CONFIG5 0x22 /* Period35 */
+#define PIXPAPER_BTST_CONFIG6 0x2E /* Strength47 */
+#define PIXPAPER_BTST_CONFIG7 0x21 /* Period34 */
+
+/* R12H: DRF (Display Refresh) */
+#define PIXPAPER_DRF_VCOM_AC 0x00 /* AC VCOM: VCOM follows LUTC (default) */
+#define PIXPAPER_DRF_VCOM_DC 0x01 /* DC VCOM: VCOM fixed to VCOMDC */
+
+/* R30H PLL - PLL Control Register */
+/* First Parameter */
+#define PIXPAPER_PLL_FR_MASK (0x7 << 0) /* Bits 2-0: FR, frame rate */
+#define PIXPAPER_PLL_FR_12_5HZ (0x0 << 0) /* 000: 12.5 Hz */
+#define PIXPAPER_PLL_FR_25HZ (0x1 << 0)	/* 001: 25 Hz */
+#define PIXPAPER_PLL_FR_50HZ (0x2 << 0) /* 010: 50 Hz (default) */
+#define PIXPAPER_PLL_FR_65HZ (0x3 << 0) /* 011: 65 Hz */
+#define PIXPAPER_PLL_FR_75HZ (0x4 << 0) /* 100: 75 Hz */
+#define PIXPAPER_PLL_FR_85HZ (0x5 << 0) /* 101: 85 Hz */
+#define PIXPAPER_PLL_FR_100HZ (0x6 << 0) /* 110: 100 Hz */
+#define PIXPAPER_PLL_FR_120HZ (0x7 << 0) /* 111: 120 Hz */
+#define PIXPAPER_PLL_DFR \
+	(1 << 3) /* Bit 3: Dynamic frame rate, 0=disabled (default), 1=enabled */
+#define PIXPAPER_PLL_CONFIG \
+	(PIXPAPER_PLL_FR_50HZ) /* 0x02: 50 Hz, dynamic frame rate disabled */
+
+/* R41H TSE - Temperature Sensor Calibration Register */
+/* First Parameter */
+#define PIXPAPER_TSE_TO_MASK \
+	(0xF << 0) /* Bits 3-0: TO[3:0], temperature offset */
+#define PIXPAPER_TSE_TO_POS_0C (0x0 << 0) /* 0000: +0°C (default) */
+#define PIXPAPER_TSE_TO_POS_0_5C (0x1 << 0) /* 0001: +0.5°C */
+#define PIXPAPER_TSE_TO_POS_1C (0x2 << 0) /* 0010: +1°C */
+#define PIXPAPER_TSE_TO_POS_1_5C (0x3 << 0) /* 0011: +1.5°C */
+#define PIXPAPER_TSE_TO_POS_2C (0x4 << 0) /* 0100: +2°C */
+#define PIXPAPER_TSE_TO_POS_2_5C (0x5 << 0) /* 0101: +2.5°C */
+#define PIXPAPER_TSE_TO_POS_3C (0x6 << 0) /* 0110: +3°C */
+#define PIXPAPER_TSE_TO_POS_3_5C (0x7 << 0) /* 0111: +3.5°C */
+#define PIXPAPER_TSE_TO_NEG_4C (0x8 << 0) /* 1000: -4°C */
+#define PIXPAPER_TSE_TO_NEG_3_5C (0x9 << 0) /* 1001: -3.5°C */
+#define PIXPAPER_TSE_TO_NEG_3C (0xA << 0) /* 1010: -3°C */
+#define PIXPAPER_TSE_TO_NEG_2_5C (0xB << 0) /* 1011: -2.5°C */
+#define PIXPAPER_TSE_TO_NEG_2C (0xC << 0) /* 1100: -2°C */
+#define PIXPAPER_TSE_TO_NEG_1_5C (0xD << 0) /* 1101: -1.5°C */
+#define PIXPAPER_TSE_TO_NEG_1C (0xE << 0) /* 1110: -1°C */
+#define PIXPAPER_TSE_TO_NEG_0_5C (0xF << 0) /* 1111: -0.5°C */
+#define PIXPAPER_TSE_TO_FINE_MASK \
+	(0x3 << 4) /* Bits 5-4: TO[5:4], fine adjustment for positive offsets */
+#define PIXPAPER_TSE_TO_FINE_0C (0x0 << 4) /* 00: +0.0°C (default) */
+#define PIXPAPER_TSE_TO_FINE_0_25C (0x1 << 4) /* 01: +0.25°C */
+#define PIXPAPER_TSE_ENABLE \
+	(0 << 7) /* Bit 7: TSE, 0=internal sensor enabled (default), 1=disabled (external) */
+#define PIXPAPER_TSE_DISABLE \
+	(1 << 7) /* Bit 7: TSE, 1=internal sensor disabled, use external */
+#define PIXPAPER_TSE_CONFIG                                 \
+	(PIXPAPER_TSE_TO_POS_0C | PIXPAPER_TSE_TO_FINE_0C | \
+	 PIXPAPER_TSE_ENABLE) /* 0x00: Internal sensor enabled, +0°C offset */
+
+/* R4DH */
+#define PIXPAPER_UNKNOWN_4D_CONFIG \
+	0x78 /* This value is essential for initialization, derived from userspace examples. */
+
+/* R50H CDI - VCOM and DATA Interval Setting Register */
+/* First Parameter */
+#define PIXPAPER_CDI_INTERVAL_MASK \
+	(0xF << 0) /* Bits 3-0: CDI[3:0], VCOM and data interval (hsync) */
+#define PIXPAPER_CDI_17_HSYNC (0x0 << 0) /* 0000: 17 hsync */
+#define PIXPAPER_CDI_16_HSYNC (0x1 << 0) /* 0001: 16 hsync */
+#define PIXPAPER_CDI_15_HSYNC (0x2 << 0) /* 0010: 15 hsync */
+#define PIXPAPER_CDI_14_HSYNC (0x3 << 0) /* 0011: 14 hsync */
+#define PIXPAPER_CDI_13_HSYNC (0x4 << 0) /* 0100: 13 hsync */
+#define PIXPAPER_CDI_12_HSYNC (0x5 << 0) /* 0101: 12 hsync */
+#define PIXPAPER_CDI_11_HSYNC (0x6 << 0) /* 0110: 11 hsync */
+#define PIXPAPER_CDI_10_HSYNC (0x7 << 0) /* 0111: 10 hsync (default) */
+#define PIXPAPER_CDI_9_HSYNC (0x8 << 0) /* 1000: 9 hsync */
+#define PIXPAPER_CDI_8_HSYNC (0x9 << 0) /* 1001: 8 hsync */
+#define PIXPAPER_CDI_7_HSYNC (0xA << 0) /* 1010: 7 hsync */
+#define PIXPAPER_CDI_6_HSYNC (0xB << 0) /* 1011: 6 hsync */
+#define PIXPAPER_CDI_5_HSYNC (0xC << 0) /* 1100: 5 hsync */
+#define PIXPAPER_CDI_4_HSYNC (0xD << 0) /* 1101: 4 hsync */
+#define PIXPAPER_CDI_3_HSYNC (0xE << 0) /* 1110: 3 hsync */
+#define PIXPAPER_CDI_2_HSYNC (0xF << 0) /* 1111: 2 hsync */
+#define PIXPAPER_CDI_DDX \
+	(1 << 4) /* Bit 4: DDX, 0=grayscale mapping 0, 1=grayscale mapping 1 (default) */
+#define PIXPAPER_CDI_VBD_MASK \
+	(0x7 << 5) /* Bits 7-5: VBD[2:0], border data selection */
+#define PIXPAPER_CDI_VBD_FLOAT (0x0 << 5) /* 000: Floating (DDX=0 or 1) */
+#define PIXPAPER_CDI_VBD_GRAY3_DDX0 \
+	(0x1 << 5) /* 001: Gray3 (border_buf=011) when DDX=0 */
+#define PIXPAPER_CDI_VBD_GRAY2_DDX0 \
+	(0x2 << 5) /* 010: Gray2 (border_buf=010) when DDX=0 */
+#define PIXPAPER_CDI_VBD_GRAY1_DDX0 \
+	(0x3 << 5) /* 011: Gray1 (border_buf=001) when DDX=0 */
+#define PIXPAPER_CDI_VBD_GRAY0_DDX0 \
+	(0x4 << 5) /* 100: Gray0 (border_buf=000) when DDX=0 */
+#define PIXPAPER_CDI_VBD_GRAY0_DDX1 \
+	(0x0 << 5) /* 000: Gray0 (border_buf=000) when DDX=1 */
+#define PIXPAPER_CDI_VBD_GRAY1_DDX1 \
+	(0x1 << 5) /* 001: Gray1 (border_buf=001) when DDX=1 */
+#define PIXPAPER_CDI_VBD_GRAY2_DDX1 \
+	(0x2 << 5) /* 010: Gray2 (border_buf=010) when DDX=1 */
+#define PIXPAPER_CDI_VBD_GRAY3_DDX1 \
+	(0x3 << 5) /* 011: Gray3 (border_buf=011) when DDX=1 */
+#define PIXPAPER_CDI_VBD_FLOAT_DDX1 (0x4 << 5) /* 100: Floating when DDX=1 */
+#define PIXPAPER_CDI_CONFIG                         \
+	(PIXPAPER_CDI_10_HSYNC | PIXPAPER_CDI_DDX | \
+	 PIXPAPER_CDI_VBD_GRAY1_DDX1) /* 0x37: 10 hsync, DDX=1, border Gray1 */
+
+/* R60H */
+#define PIXPAPER_UNKNOWN_60_CONFIG1 \
+	0x02 /* This value is essential for initialization, derived from userspace examples. */
+#define PIXPAPER_UNKNOWN_60_CONFIG2 \
+	0x02 /* This value is essential for initialization, derived from userspace examples. */
+
+/* R61H TRES - Resolution Setting Register */
+#define PIXPAPER_TRES_HRES_H                  \
+	((PIXPAPER_PANEL_BUFFER_WIDTH >> 8) & \
+	 0xFF) /* HRES[9:8]: High byte of horizontal resolution (128) */
+#define PIXPAPER_TRES_HRES_L           \
+	(PIXPAPER_PANEL_BUFFER_WIDTH & \
+	 0xFF) /* HRES[7:0]: Low byte of horizontal resolution (128 = 0x80) */
+#define PIXPAPER_TRES_VRES_H      \
+	((PIXPAPER_HEIGHT >> 8) & \
+	 0xFF) /* VRES[9:8]: High byte of vertical resolution (250) */
+#define PIXPAPER_TRES_VRES_L \
+	(PIXPAPER_HEIGHT &   \
+	 0xFF) /* VRES[7:0]: Low byte of vertical resolution (250 = 0xFA) */
+
+/* R65H GSST - Gate/Source Start Setting Register */
+#define PIXPAPER_GSST_S_START 0x00 /* S_Start[7:0]: First source line (S0) */
+#define PIXPAPER_GSST_RESERVED 0x00 /* Reserved byte */
+#define PIXPAPER_GSST_G_START_H \
+	0x00 /* G_Start[8]: High bit of first gate line (G0) */
+#define PIXPAPER_GSST_G_START_L \
+	0x00 /* G_Start[7:0]: Low byte of first gate line (G0) */
+
+/* RB4H */
+#define PIXPAPER_UNKNOWN_B4_CONFIG \
+	0xD0 /* This value is essential for initialization, derived from userspace examples. */
+
+/* RB5H */
+#define PIXPAPER_UNKNOWN_B5_CONFIG \
+	0x03 /* This value is essential for initialization, derived from userspace examples. */
+
+/* RE0H */
+#define PIXPAPER_UNKNOWN_E0_CONFIG \
+	0x00 /* This value is essential for initialization, derived from userspace examples. */
+
+/* RE3H PWS - Power Saving Register */
+/* First Parameter */
+#define PIXPAPER_PWS_VCOM_W_MASK \
+	(0xF                     \
+	 << 4) /* Bits 7-4: VCOM_W[3:0], VCOM power-saving width (line periods) */
+#define PIXPAPER_PWS_VCOM_W_0 (0x0 << 4) /* 0000: 0 line periods */
+#define PIXPAPER_PWS_VCOM_W_1 (0x1 << 4) /* 0001: 1 line period */
+#define PIXPAPER_PWS_VCOM_W_2 (0x2 << 4) /* 0010: 2 line periods */
+#define PIXPAPER_PWS_VCOM_W_3 (0x3 << 4) /* 0011: 3 line periods */
+#define PIXPAPER_PWS_VCOM_W_4 (0x4 << 4) /* 0100: 4 line periods */
+#define PIXPAPER_PWS_VCOM_W_5 (0x5 << 4) /* 0101: 5 line periods */
+#define PIXPAPER_PWS_VCOM_W_6 (0x6 << 4) /* 0110: 6 line periods */
+#define PIXPAPER_PWS_VCOM_W_7 (0x7 << 4) /* 0111: 7 line periods */
+#define PIXPAPER_PWS_VCOM_W_8 (0x8 << 4) /* 1000: 8 line periods */
+#define PIXPAPER_PWS_VCOM_W_9 (0x9 << 4) /* 1001: 9 line periods */
+#define PIXPAPER_PWS_VCOM_W_10 (0xA << 4) /* 1010: 10 line periods */
+#define PIXPAPER_PWS_VCOM_W_11 (0xB << 4) /* 1011: 11 line periods */
+#define PIXPAPER_PWS_VCOM_W_12 (0xC << 4) /* 1100: 12 line periods */
+#define PIXPAPER_PWS_VCOM_W_13 (0xD << 4) /* 1101: 13 line periods */
+#define PIXPAPER_PWS_VCOM_W_14 (0xE << 4) /* 1110: 14 line periods */
+#define PIXPAPER_PWS_VCOM_W_15 (0xF << 4) /* 1111: 15 line periods */
+#define PIXPAPER_PWS_SD_W_MASK \
+	(0xF << 0) /* Bits 3-0: SD_W[3:0], source power-saving width (660 ns units) */
+#define PIXPAPER_PWS_SD_W_0 (0x0 << 0) /* 0000: 0 ns */
+#define PIXPAPER_PWS_SD_W_1 (0x1 << 0) /* 0001: 660 ns */
+#define PIXPAPER_PWS_SD_W_2 (0x2 << 0) /* 0010: 1320 ns */
+#define PIXPAPER_PWS_SD_W_3 (0x3 << 0) /* 0011: 1980 ns */
+#define PIXPAPER_PWS_SD_W_4 (0x4 << 0) /* 0100: 2640 ns */
+#define PIXPAPER_PWS_SD_W_5 (0x5 << 0) /* 0101: 3300 ns */
+#define PIXPAPER_PWS_SD_W_6 (0x6 << 0) /* 0110: 3960 ns */
+#define PIXPAPER_PWS_SD_W_7 (0x7 << 0) /* 0111: 4620 ns */
+#define PIXPAPER_PWS_SD_W_8 (0x8 << 0) /* 1000: 5280 ns */
+#define PIXPAPER_PWS_SD_W_9 (0x9 << 0) /* 1001: 5940 ns */
+#define PIXPAPER_PWS_SD_W_10 (0xA << 0) /* 1010: 6600 ns */
+#define PIXPAPER_PWS_SD_W_11 (0xB << 0) /* 1011: 7260 ns */
+#define PIXPAPER_PWS_SD_W_12 (0xC << 0) /* 1100: 7920 ns */
+#define PIXPAPER_PWS_SD_W_13 (0xD << 0) /* 1101: 8580 ns */
+#define PIXPAPER_PWS_SD_W_14 (0xE << 0) /* 1110: 9240 ns */
+#define PIXPAPER_PWS_SD_W_15 (0xF << 0) /* 1111: 9900 ns */
+#define PIXPAPER_PWS_CONFIG      \
+	(PIXPAPER_PWS_VCOM_W_2 | \
+	 PIXPAPER_PWS_SD_W_2) /* 0x22: VCOM 2 line periods (160 µs), source 1320 ns */
+
+/* RE7H */
+#define PIXPAPER_UNKNOWN_E7_CONFIG \
+	0x1C /* This value is essential for initialization, derived from userspace examples. */
+
+/* RE9H */
+#define PIXPAPER_UNKNOWN_E9_CONFIG \
+	0x01 /* This value is essential for initialization, derived from userspace examples. */
+
+#endif /* __PIXPAPER_REGS_H__ */

drivers/gpu/drm/tiny/pixpaper.c new file +87 -0

new file mode 100644
index 0000000000000000000000000000000000000000..75643ed337120b5713706e0cbd942785db2aba12
@@ -0,0 +1,789 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * DRM driver for PIXPAPER e-ink panel
+ *
+ * Author: LiangCheng Wang <[email protected]>,
+ */
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+
+#include <drm/clients/drm_client_setup.h>
+#include <drm/drm_atomic.h>
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_fbdev_shmem.h>
+#include <drm/drm_framebuffer.h>
+#include <drm/drm_gem_atomic_helper.h>
+#include <drm/drm_gem_shmem_helper.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_probe_helper.h>
+
+#include "pixpaper-regs.h"
+
+MODULE_IMPORT_NS("DMA_BUF");
+
+/*
+ * The panel has a visible resolution of 122x250.
+ * However, the controller requires the horizontal resolution to be aligned to 128 pixels.
+ * No porch or sync timing values are provided in the datasheet, so we define minimal
+ * placeholder values to satisfy the DRM framework.
+ */
+
+/* Panel visible resolution */
+#define PIXPAPER_WIDTH           122
+#define PIXPAPER_HEIGHT          250
+
+/* Controller requires 128 horizontal pixels total (for memory alignment) */
+#define PIXPAPER_HTOTAL          128
+#define PIXPAPER_HFP             2
+#define PIXPAPER_HSYNC           2
+#define PIXPAPER_HBP             (PIXPAPER_HTOTAL - PIXPAPER_WIDTH - PIXPAPER_HFP - PIXPAPER_HSYNC)
+
+/*
+ * According to the datasheet, the total vertical blanking must be 55 lines,
+ * regardless of how the vertical back porch is set.
+ * Here we allocate VFP=2, VSYNC=2, and VBP=51 to sum up to 55 lines.
+ * Total vertical lines = 250 (visible) + 55 (blanking) = 305.
+ */
+#define PIXPAPER_VTOTAL  (250 + 55)
+#define PIXPAPER_VFP     2
+#define PIXPAPER_VSYNC   2
+#define PIXPAPER_VBP     (55 - PIXPAPER_VFP - PIXPAPER_VSYNC)
+
+/*
+ * Pixel clock calculation:
+ * pixel_clock = htotal * vtotal * refresh_rate
+ *             = 128 * 305 * 50
+ *             = 1,952,000 Hz = 1952 kHz
+ */
+#define PIXPAPER_PIXEL_CLOCK     1952
+
+#define PIXPAPER_WIDTH_MM        24    /* approximate from 23.7046mm */
+#define PIXPAPER_HEIGHT_MM       49    /* approximate from 48.55mm */
+
+#define PIXPAPER_SPI_BITS_PER_WORD	8
+#define PIXPAPER_SPI_SPEED_DEFAULT      1000000
+
+#define PIXPAPER_PANEL_BUFFER_WIDTH	128
+#define PIXPAPER_PANEL_BUFFER_TWO_BYTES_PER_ROW (PIXPAPER_PANEL_BUFFER_WIDTH / 4)
+
+#define PIXPAPER_COLOR_THRESHOLD_LOW_CHANNEL		60
+#define PIXPAPER_COLOR_THRESHOLD_HIGH_CHANNEL		200
+#define PIXPAPER_COLOR_THRESHOLD_YELLOW_MIN_GREEN	180
+
+struct pixpaper_error_ctx {
+	int errno_code;
+};
+
+struct pixpaper_panel {
+	struct drm_device drm;
+	struct drm_plane plane;
+	struct drm_crtc crtc;
+	struct drm_encoder encoder;
+	struct drm_connector connector;
+
+	struct spi_device *spi;
+	struct gpio_desc *reset;

drivers/gpu/drm/tiny/pixpaper.c new file +219 -0

+{
+	unsigned int timeout_ms = 10000;
+	unsigned long timeout_jiffies = jiffies + msecs_to_jiffies(timeout_ms);
+
+	usleep_range(1000, 1500);
+	while (gpiod_get_value_cansleep(panel->busy) != 1) {
+		if (time_after(jiffies, timeout_jiffies)) {
+			drm_warn(&panel->drm, "Busy wait timed out\n");
+			return;
+		}
+		usleep_range(100, 200);
+	}
+}
+
+static void pixpaper_spi_sync(struct spi_device *spi, struct spi_message *msg,
+			      struct pixpaper_error_ctx *err)
+{
+	if (err->errno_code)
+		return;
+
+	int ret = spi_sync(spi, msg);
+
+	if (ret < 0)
+		err->errno_code = ret;
+}
+
+static void pixpaper_send_cmd(struct pixpaper_panel *panel, u8 cmd,
+			      struct pixpaper_error_ctx *err)
+{
+	if (err->errno_code)
+		return;
+
+	struct spi_transfer xfer = {
+		.tx_buf = &cmd,
+		.len = 1,
+	};
+	struct spi_message msg;
+
+	spi_message_init(&msg);
+	spi_message_add_tail(&xfer, &msg);
+
+	gpiod_set_value_cansleep(panel->dc, 0);
+	usleep_range(1, 5);
+	pixpaper_spi_sync(panel->spi, &msg, err);
+}
+
+static void pixpaper_send_data(struct pixpaper_panel *panel, u8 data,
+			       struct pixpaper_error_ctx *err)
+{
+	if (err->errno_code)
+		return;
+
+	struct spi_transfer xfer = {
+		.tx_buf = &data,
+		.len = 1,
+	};
+	struct spi_message msg;
+
+	spi_message_init(&msg);
+	spi_message_add_tail(&xfer, &msg);
+
+	gpiod_set_value_cansleep(panel->dc, 1);
+	usleep_range(1, 5);
+	pixpaper_spi_sync(panel->spi, &msg, err);
+}
+
+static int pixpaper_panel_hw_init(struct pixpaper_panel *panel)
+{
+	struct pixpaper_error_ctx err = { .errno_code = 0 };
+
+	gpiod_set_value_cansleep(panel->reset, 0);
+	msleep(50);
+	gpiod_set_value_cansleep(panel->reset, 1);
+	msleep(50);
+
+	pixpaper_wait_busy(panel);
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_UNKNOWN_4D, &err);
+	pixpaper_send_data(panel, PIXPAPER_UNKNOWN_4D_CONFIG, &err);
+	if (err.errno_code)
+		goto init_fail;
+	pixpaper_wait_busy(panel);
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_PANEL_SETTING, &err);
+	pixpaper_send_data(panel, PIXPAPER_PSR_CONFIG, &err);
+	pixpaper_send_data(panel, PIXPAPER_PSR_CONFIG2, &err);
+	if (err.errno_code)
+		goto init_fail;
+	pixpaper_wait_busy(panel);
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_POWER_SETTING, &err);
+	pixpaper_send_data(panel, PIXPAPER_PWR_CONFIG1, &err);
+	pixpaper_send_data(panel, PIXPAPER_PWR_CONFIG2, &err);
+	pixpaper_send_data(panel, PIXPAPER_PWR_VSP_8_2V, &err);
+	pixpaper_send_data(panel, PIXPAPER_PWR_VSPL_15V, &err);
+	pixpaper_send_data(panel, PIXPAPER_PWR_VSN_4V, &err);
+	pixpaper_send_data(panel, PIXPAPER_PWR_VSP_8_2V, &err);
+	if (err.errno_code)
+		goto init_fail;
+	pixpaper_wait_busy(panel);
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_POWER_OFF_SEQUENCE, &err);
+	pixpaper_send_data(panel, PIXPAPER_PFS_CONFIG1, &err);
+	pixpaper_send_data(panel, PIXPAPER_PFS_CONFIG2, &err);
+	pixpaper_send_data(panel, PIXPAPER_PFS_CONFIG3, &err);
+	if (err.errno_code)
+		goto init_fail;
+	pixpaper_wait_busy(panel);
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_BOOSTER_SOFT_START, &err);
+	pixpaper_send_data(panel, PIXPAPER_BTST_CONFIG1, &err);
+	pixpaper_send_data(panel, PIXPAPER_BTST_CONFIG2, &err);
+	pixpaper_send_data(panel, PIXPAPER_BTST_CONFIG3, &err);
+	pixpaper_send_data(panel, PIXPAPER_BTST_CONFIG4, &err);
+	pixpaper_send_data(panel, PIXPAPER_BTST_CONFIG5, &err);
+	pixpaper_send_data(panel, PIXPAPER_BTST_CONFIG6, &err);
+	pixpaper_send_data(panel, PIXPAPER_BTST_CONFIG7, &err);
+	if (err.errno_code)
+		goto init_fail;
+	pixpaper_wait_busy(panel);
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_PLL_CONTROL, &err);
+	pixpaper_send_data(panel, PIXPAPER_PLL_CONFIG, &err);
+	if (err.errno_code)
+		goto init_fail;
+	pixpaper_wait_busy(panel);
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_TEMP_SENSOR_CALIB, &err);
+	pixpaper_send_data(panel, PIXPAPER_TSE_CONFIG, &err);
+	if (err.errno_code)
+		goto init_fail;
+	pixpaper_wait_busy(panel);
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_VCOM_INTERVAL, &err);
+	pixpaper_send_data(panel, PIXPAPER_CDI_CONFIG, &err);
+	if (err.errno_code)
+		goto init_fail;
+	pixpaper_wait_busy(panel);
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_UNKNOWN_60, &err);
+	pixpaper_send_data(panel, PIXPAPER_UNKNOWN_60_CONFIG1, &err);
+	pixpaper_send_data(panel, PIXPAPER_UNKNOWN_60_CONFIG2, &err);
+	if (err.errno_code)
+		goto init_fail;
+	pixpaper_wait_busy(panel);
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_RESOLUTION_SETTING, &err);
+	pixpaper_send_data(panel, PIXPAPER_TRES_HRES_H, &err);
+	pixpaper_send_data(panel, PIXPAPER_TRES_HRES_L, &err);
+	pixpaper_send_data(panel, PIXPAPER_TRES_VRES_H, &err);
+	pixpaper_send_data(panel, PIXPAPER_TRES_VRES_L, &err);
+	if (err.errno_code)
+		goto init_fail;
+	pixpaper_wait_busy(panel);
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_GATE_SOURCE_START, &err);
+	pixpaper_send_data(panel, PIXPAPER_GSST_S_START, &err);
+	pixpaper_send_data(panel, PIXPAPER_GSST_RESERVED, &err);
+	pixpaper_send_data(panel, PIXPAPER_GSST_G_START_H, &err);
+	pixpaper_send_data(panel, PIXPAPER_GSST_G_START_L, &err);
+	if (err.errno_code)
+		goto init_fail;
+	pixpaper_wait_busy(panel);
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_UNKNOWN_E7, &err);
+	pixpaper_send_data(panel, PIXPAPER_UNKNOWN_E7_CONFIG, &err);
+	if (err.errno_code)
+		goto init_fail;
+	pixpaper_wait_busy(panel);
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_POWER_SAVING, &err);
+	pixpaper_send_data(panel, PIXPAPER_PWS_CONFIG, &err);
+	if (err.errno_code)
+		goto init_fail;
+	pixpaper_wait_busy(panel);
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_UNKNOWN_E0, &err);
+	pixpaper_send_data(panel, PIXPAPER_UNKNOWN_E0_CONFIG, &err);
+	if (err.errno_code)
+		goto init_fail;
+	pixpaper_wait_busy(panel);
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_UNKNOWN_B4, &err);
+	pixpaper_send_data(panel, PIXPAPER_UNKNOWN_B4_CONFIG, &err);
+	if (err.errno_code)
+		goto init_fail;
+	pixpaper_wait_busy(panel);
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_UNKNOWN_B5, &err);
+	pixpaper_send_data(panel, PIXPAPER_UNKNOWN_B5_CONFIG, &err);
+	if (err.errno_code)
+		goto init_fail;
+	pixpaper_wait_busy(panel);
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_UNKNOWN_E9, &err);
+	pixpaper_send_data(panel, PIXPAPER_UNKNOWN_E9_CONFIG, &err);
+	if (err.errno_code)
+		goto init_fail;
+	pixpaper_wait_busy(panel);
+
+	return 0;
+
+init_fail:
+	drm_err(&panel->drm, "Hardware initialization failed (err=%d)\n",
+		err.errno_code);
+	return err.errno_code;
+}
+
+/*
+ * Convert framebuffer pixels to 2-bit e-paper format:
+ *   00 - White
+ *   01 - Black
+ *   10 - Yellow
+ *   11 - Red
+ */
+static u8 pack_pixels_to_byte(u32 *src_pixels, int i, int j,
+			      struct drm_framebuffer *fb)
+{
+	u8 packed_byte = 0;

drivers/gpu/drm/tiny/pixpaper.c new file +73 -0

+			u32 r = (pixel >> 16) & 0xFF;
+			u32 g = (pixel >> 8) & 0xFF;
+			u32 b = pixel & 0xFF;
+
+			if (r < PIXPAPER_COLOR_THRESHOLD_LOW_CHANNEL &&
+			    g < PIXPAPER_COLOR_THRESHOLD_LOW_CHANNEL &&
+			    b < PIXPAPER_COLOR_THRESHOLD_LOW_CHANNEL) {
+				two_bit_val = 0b00;
+			} else if (r > PIXPAPER_COLOR_THRESHOLD_HIGH_CHANNEL &&
+				   g > PIXPAPER_COLOR_THRESHOLD_HIGH_CHANNEL &&
+				   b > PIXPAPER_COLOR_THRESHOLD_HIGH_CHANNEL) {
+				two_bit_val = 0b01;
+			} else if (r > PIXPAPER_COLOR_THRESHOLD_HIGH_CHANNEL &&
+				   g < PIXPAPER_COLOR_THRESHOLD_LOW_CHANNEL &&
+				   b < PIXPAPER_COLOR_THRESHOLD_LOW_CHANNEL) {
+				two_bit_val = 0b11;
+			} else if (r > PIXPAPER_COLOR_THRESHOLD_HIGH_CHANNEL &&
+				   g > PIXPAPER_COLOR_THRESHOLD_YELLOW_MIN_GREEN &&
+				   b < PIXPAPER_COLOR_THRESHOLD_LOW_CHANNEL) {
+				two_bit_val = 0b10;
+			} else {
+				two_bit_val = 0b01;
+			}
+		} else {
+			two_bit_val = 0b01;
+		}
+
+		packed_byte |= two_bit_val << ((3 - k) * 2);
+	}
+
+	return packed_byte;
+}
+
+static int pixpaper_plane_helper_atomic_check(struct drm_plane *plane,
+					      struct drm_atomic_state *state)
+{
+	struct drm_plane_state *new_plane_state =
+		drm_atomic_get_new_plane_state(state, plane);
+	struct drm_crtc *new_crtc = new_plane_state->crtc;
+	struct drm_crtc_state *new_crtc_state = NULL;
+	int ret;
+
+	if (new_crtc)
+		new_crtc_state = drm_atomic_get_new_crtc_state(state, new_crtc);
+
+	ret = drm_atomic_helper_check_plane_state(new_plane_state,
+						  new_crtc_state, DRM_PLANE_NO_SCALING,
+						  DRM_PLANE_NO_SCALING, false, false);
+	if (ret)
+		return ret;
+	else if (!new_plane_state->visible)
+		return 0;
+
+	return 0;
+}
+
+static int pixpaper_crtc_helper_atomic_check(struct drm_crtc *crtc,
+					     struct drm_atomic_state *state)
+{
+	struct drm_crtc_state *crtc_state =
+		drm_atomic_get_new_crtc_state(state, crtc);
+
+	if (!crtc_state->enable)
+		return 0;
+
+	return drm_atomic_helper_check_crtc_primary_plane(crtc_state);
+}
+
+static void pixpaper_crtc_atomic_enable(struct drm_crtc *crtc,
+					struct drm_atomic_state *state)
+{
+	struct pixpaper_panel *panel = to_pixpaper_panel(crtc->dev);
+	struct drm_device *drm = &panel->drm;

drivers/gpu/drm/tiny/pixpaper.c new file +112 -0

+		goto exit_drm_dev;
+	}
+
+	pixpaper_wait_busy(panel);
+
+	drm_dbg(drm, "Panel enabled and powered on\n");
+
+exit_drm_dev:
+	drm_dev_exit(idx);
+}
+
+static void pixpaper_crtc_atomic_disable(struct drm_crtc *crtc,
+					 struct drm_atomic_state *state)
+{
+	struct pixpaper_panel *panel = to_pixpaper_panel(crtc->dev);
+	struct drm_device *drm = &panel->drm;
+	struct pixpaper_error_ctx err = { .errno_code = 0 };
+	int idx;
+
+	if (!drm_dev_enter(drm, &idx))
+		return;
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_POWER_OFF, &err);
+	if (err.errno_code) {
+		drm_err(drm, "Failed to send POF command: %d\n",
+			err.errno_code);
+		goto exit_drm_dev;
+	}
+	pixpaper_wait_busy(panel);
+
+	drm_dbg(drm, "Panel disabled\n");
+
+exit_drm_dev:
+	drm_dev_exit(idx);
+}
+
+static void pixpaper_plane_atomic_update(struct drm_plane *plane,
+					 struct drm_atomic_state *state)
+{
+	struct drm_plane_state *plane_state =
+		drm_atomic_get_new_plane_state(state, plane);
+	struct drm_shadow_plane_state *shadow_plane_state =
+		to_drm_shadow_plane_state(plane_state);
+	struct drm_crtc *crtc = plane_state->crtc;
+	struct pixpaper_panel *panel = to_pixpaper_panel(crtc->dev);
+
+	struct drm_device *drm = &panel->drm;
+	struct drm_framebuffer *fb = plane_state->fb;
+	struct iosys_map map = shadow_plane_state->data[0];
+	void *vaddr = map.vaddr;
+	int i, j, idx;
+	u32 *src_pixels = NULL;
+	struct pixpaper_error_ctx err = { .errno_code = 0 };
+
+	if (!drm_dev_enter(drm, &idx))
+		return;
+
+	drm_dbg(drm, "Starting frame update (phys=%dx%d, buf_w=%d)\n",
+		PIXPAPER_WIDTH, PIXPAPER_HEIGHT, PIXPAPER_PANEL_BUFFER_WIDTH);
+
+	if (!fb || !plane_state->visible) {
+		drm_err(drm,
+			"No framebuffer or plane not visible, skipping update\n");
+		goto update_cleanup;
+	}
+
+	src_pixels = (u32 *)vaddr;
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_DATA_START_TRANSMISSION, &err);
+	if (err.errno_code)
+		goto update_cleanup;
+
+	pixpaper_wait_busy(panel);
+
+	for (i = 0; i < PIXPAPER_HEIGHT; i++) {
+		for (j = 0; j < PIXPAPER_PANEL_BUFFER_TWO_BYTES_PER_ROW; j++) {
+			u8 packed_byte =
+				pack_pixels_to_byte(src_pixels, i, j, fb);
+
+			pixpaper_wait_busy(panel);
+			pixpaper_send_data(panel, packed_byte, &err);
+		}
+	}
+	pixpaper_wait_busy(panel);
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_POWER_ON, &err);
+	if (err.errno_code) {
+		drm_err(drm, "Failed to send PON command: %d\n",
+			err.errno_code);
+		goto update_cleanup;
+	}
+	pixpaper_wait_busy(panel);
+
+	pixpaper_send_cmd(panel, PIXPAPER_CMD_DISPLAY_REFRESH, &err);
+	pixpaper_send_data(panel, PIXPAPER_DRF_VCOM_AC, &err);
+	if (err.errno_code) {
+		drm_err(drm, "Failed sending data after DRF: %d\n",
+			err.errno_code);
+		goto update_cleanup;
+	}
+	pixpaper_wait_busy(panel);
+
+update_cleanup:
+	if (err.errno_code && err.errno_code != -ETIMEDOUT)
+		drm_err(drm, "Frame update function failed with error %d\n",
+			err.errno_code);
+
+	drm_dev_exit(idx);
+}
+
+static int pixpaper_connector_get_modes(struct drm_connector *connector)
+{

drivers/gpu/drm/tiny/pixpaper.c new file +7 -0

+		return 0;
+	}
+
+	mode->hdisplay     = PIXPAPER_WIDTH;
+	mode->hsync_start  = PIXPAPER_WIDTH + PIXPAPER_HFP;
+	mode->hsync_end    = mode->hsync_start + PIXPAPER_HSYNC;
+	mode->htotal       = PIXPAPER_HTOTAL;

drivers/gpu/drm/tiny/pixpaper.c new file +64 -0

+		drm_mode_destroy(connector->dev, mode);
+		return 0;
+	}
+
+	drm_mode_probed_add(connector, mode);
+	drm_dbg(connector->dev, "Added mode '%s' (%dx%d@%d) to connector %s\n",
+		mode->name, mode->hdisplay, mode->vdisplay,
+		drm_mode_vrefresh(mode), connector->name);
+
+	connector->display_info.width_mm  = PIXPAPER_WIDTH_MM;
+	connector->display_info.height_mm = PIXPAPER_HEIGHT_MM;
+
+	return 1;
+}
+
+static const struct drm_plane_funcs pixpaper_plane_funcs = {
+	.update_plane = drm_atomic_helper_update_plane,
+	.disable_plane = drm_atomic_helper_disable_plane,
+	.destroy = drm_plane_cleanup,
+	DRM_GEM_SHADOW_PLANE_FUNCS,
+};
+
+static const struct drm_plane_helper_funcs pixpaper_plane_helper_funcs = {
+	DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
+	.atomic_check = pixpaper_plane_helper_atomic_check,
+	.atomic_update = pixpaper_plane_atomic_update,
+};
+
+static const struct drm_crtc_funcs pixpaper_crtc_funcs = {
+	.set_config = drm_atomic_helper_set_config,
+	.page_flip = drm_atomic_helper_page_flip,
+	.reset = drm_atomic_helper_crtc_reset,
+	.destroy = drm_crtc_cleanup,
+	.atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
+};
+
+static const struct drm_crtc_helper_funcs pixpaper_crtc_helper_funcs = {
+	.atomic_check = pixpaper_crtc_helper_atomic_check,
+	.atomic_enable = pixpaper_crtc_atomic_enable,
+	.atomic_disable = pixpaper_crtc_atomic_disable,
+};
+
+static const struct drm_encoder_funcs pixpaper_encoder_funcs = {
+	.destroy = drm_encoder_cleanup,
+};
+
+static const struct drm_connector_funcs pixpaper_connector_funcs = {
+	.reset = drm_atomic_helper_connector_reset,
+	.fill_modes = drm_helper_probe_single_connector_modes,
+	.destroy = drm_connector_cleanup,
+	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+};
+
+static const struct drm_connector_helper_funcs pixpaper_connector_helper_funcs = {
+	.get_modes = pixpaper_connector_get_modes,
+};
+
+DEFINE_DRM_GEM_FOPS(pixpaper_fops);
+
+static struct drm_driver pixpaper_drm_driver = {
+	.driver_features = DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
+	.fops = &pixpaper_fops,

drivers/gpu/drm/tiny/pixpaper.c new file +158 -0

+{
+	if (mode->hdisplay == PIXPAPER_WIDTH &&
+	    mode->vdisplay == PIXPAPER_HEIGHT) {
+		return MODE_OK;
+	}
+	return MODE_BAD;
+}
+
+static const struct drm_mode_config_funcs pixpaper_mode_config_funcs = {
+	.fb_create = drm_gem_fb_create_with_dirty,
+	.mode_valid = pixpaper_mode_valid,
+	.atomic_check = drm_atomic_helper_check,
+	.atomic_commit = drm_atomic_helper_commit,
+};
+
+static int pixpaper_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	struct pixpaper_panel *panel;
+	struct drm_device *drm;
+	int ret;
+
+	panel = devm_drm_dev_alloc(dev, &pixpaper_drm_driver,
+				   struct pixpaper_panel, drm);
+	if (IS_ERR(panel))
+		return PTR_ERR(panel);
+
+	drm = &panel->drm;
+	panel->spi = spi;
+	spi_set_drvdata(spi, panel);
+
+	spi->mode = SPI_MODE_0;
+	spi->bits_per_word = PIXPAPER_SPI_BITS_PER_WORD;
+
+	if (!spi->max_speed_hz) {
+		drm_warn(drm,
+			 "spi-max-frequency not specified in DT, using default %u Hz\n",
+			 PIXPAPER_SPI_SPEED_DEFAULT);
+		spi->max_speed_hz = PIXPAPER_SPI_SPEED_DEFAULT;
+	}
+
+	ret = spi_setup(spi);
+	if (ret < 0) {
+		drm_err(drm, "SPI setup failed: %d\n", ret);
+		return ret;
+	}
+
+	if (!dev->dma_mask)
+		dev->dma_mask = &dev->coherent_dma_mask;
+	ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
+	if (ret) {
+		drm_err(drm, "Failed to set DMA mask: %d\n", ret);
+		return ret;
+	}
+
+	panel->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(panel->reset))
+		return PTR_ERR(panel->reset);
+
+	panel->busy = devm_gpiod_get(dev, "busy", GPIOD_IN);
+	if (IS_ERR(panel->busy))
+		return PTR_ERR(panel->busy);
+
+	panel->dc = devm_gpiod_get(dev, "dc", GPIOD_OUT_HIGH);
+	if (IS_ERR(panel->dc))
+		return PTR_ERR(panel->dc);
+
+	ret = pixpaper_panel_hw_init(panel);
+	if (ret) {
+		drm_err(drm, "Panel hardware initialization failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = drmm_mode_config_init(drm);
+	if (ret)
+		return ret;
+	drm->mode_config.funcs = &pixpaper_mode_config_funcs;
+	drm->mode_config.min_width = PIXPAPER_WIDTH;
+	drm->mode_config.max_width = PIXPAPER_WIDTH;
+	drm->mode_config.min_height = PIXPAPER_HEIGHT;
+	drm->mode_config.max_height = PIXPAPER_HEIGHT;
+
+	ret = drm_universal_plane_init(drm, &panel->plane, 1,
+				       &pixpaper_plane_funcs,
+				       (const uint32_t[]){ DRM_FORMAT_XRGB8888 },
+				       1, NULL, DRM_PLANE_TYPE_PRIMARY, NULL);
+	if (ret)
+		return ret;
+	drm_plane_helper_add(&panel->plane, &pixpaper_plane_helper_funcs);
+
+	ret = drm_crtc_init_with_planes(drm, &panel->crtc, &panel->plane, NULL,
+					&pixpaper_crtc_funcs, NULL);
+	if (ret)
+		return ret;
+	drm_crtc_helper_add(&panel->crtc, &pixpaper_crtc_helper_funcs);
+
+	ret = drm_encoder_init(drm, &panel->encoder, &pixpaper_encoder_funcs,
+			       DRM_MODE_ENCODER_NONE, NULL);
+	if (ret)
+		return ret;
+	panel->encoder.possible_crtcs = drm_crtc_mask(&panel->crtc);
+
+	ret = drm_connector_init(drm, &panel->connector,
+				 &pixpaper_connector_funcs,
+				 DRM_MODE_CONNECTOR_SPI);
+	if (ret)
+		return ret;
+
+	drm_connector_helper_add(&panel->connector,
+				 &pixpaper_connector_helper_funcs);
+	drm_connector_attach_encoder(&panel->connector, &panel->encoder);
+
+	drm_mode_config_reset(drm);
+
+	ret = drm_dev_register(drm, 0);
+	if (ret)
+		return ret;
+
+	drm_client_setup(drm, NULL);
+
+	return 0;
+}
+
+static void pixpaper_remove(struct spi_device *spi)
+{
+	struct pixpaper_panel *panel = spi_get_drvdata(spi);
+
+	if (!panel)
+		return;
+
+	drm_dev_unplug(&panel->drm);
+	drm_atomic_helper_shutdown(&panel->drm);
+}
+
+static const struct spi_device_id pixpaper_ids[] = { { "pixpaper", 0 }, {} };
+MODULE_DEVICE_TABLE(spi, pixpaper_ids);
+
+static const struct of_device_id pixpaper_dt_ids[] = {
+	{ .compatible = "mayqueen,pixpaper" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, pixpaper_dt_ids);
+
+static struct spi_driver pixpaper_spi_driver = {
+	.driver = {
+		.name = "pixpaper",
+		.of_match_table = pixpaper_dt_ids,
+	},
+	.id_table = pixpaper_ids,
+	.probe = pixpaper_probe,
+	.remove = pixpaper_remove,
+};
+
+module_spi_driver(pixpaper_spi_driver);
+
+MODULE_AUTHOR("LiangCheng Wang");
+MODULE_DESCRIPTION("DRM SPI driver for PIXPAPER e-ink panel");
+MODULE_LICENSE("GPL");