xref: /linux/drivers/gpu/drm/tiny/pixpaper.c (revision f6e8dc9edf963dbc99085e54f6ced6da9daa6100)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * DRM driver for PIXPAPER e-ink panel
4  *
5  * Author: LiangCheng Wang <zaq14760@gmail.com>,
6  */
7 #include <linux/delay.h>
8 #include <linux/module.h>
9 #include <linux/spi/spi.h>
10 
11 #include <drm/clients/drm_client_setup.h>
12 #include <drm/drm_atomic.h>
13 #include <drm/drm_atomic_helper.h>
14 #include <drm/drm_drv.h>
15 #include <drm/drm_fbdev_shmem.h>
16 #include <drm/drm_framebuffer.h>
17 #include <drm/drm_gem_atomic_helper.h>
18 #include <drm/drm_gem_shmem_helper.h>
19 #include <drm/drm_gem_framebuffer_helper.h>
20 #include <drm/drm_print.h>
21 #include <drm/drm_probe_helper.h>
22 
23 /*
24  * Note on Undocumented Commands/Registers:
25  *
26  * Several commands and register parameters defined in this header are not
27  * documented in the datasheet. Their values and usage have been derived
28  * through analysis of existing userspace example programs.
29  *
30  * These 'unknown' definitions are crucial for the proper initialization
31  * and stable operation of the panel. Modifying these values without
32  * thorough understanding may lead to display anomalies, panel damage,
33  * or unexpected behavior.
34  */
35 
36 /* Command definitions */
37 #define PIXPAPER_CMD_PANEL_SETTING 0x00	/* R00H: Panel settings */
38 #define PIXPAPER_CMD_POWER_SETTING 0x01	/* R01H: Power settings */
39 #define PIXPAPER_CMD_POWER_OFF 0x02		/* R02H: Power off */
40 #define PIXPAPER_CMD_POWER_OFF_SEQUENCE 0x03	/* R03H: Power off sequence */
41 #define PIXPAPER_CMD_POWER_ON 0x04		/* R04H: Power on */
42 #define PIXPAPER_CMD_BOOSTER_SOFT_START 0x06	/* R06H: Booster soft start */
43 #define PIXPAPER_CMD_DEEP_SLEEP 0x07		/* R07H: Deep sleep */
44 #define PIXPAPER_CMD_DATA_START_TRANSMISSION 0x10
45 /* R10H: Data transmission start */
46 #define PIXPAPER_CMD_DISPLAY_REFRESH 0x12	/* R12H: Display refresh */
47 #define PIXPAPER_CMD_PLL_CONTROL 0x30		/* R30H: PLL control */
48 #define PIXPAPER_CMD_TEMP_SENSOR_CALIB 0x41
49 /* R41H: Temperature sensor calibration */
50 #define PIXPAPER_CMD_UNKNOWN_4D 0x4D		/* R4DH: Unknown command */
51 #define PIXPAPER_CMD_VCOM_INTERVAL 0x50	/* R50H: VCOM interval */
52 #define PIXPAPER_CMD_UNKNOWN_60 0x60		/* R60H: Unknown command */
53 #define PIXPAPER_CMD_RESOLUTION_SETTING 0x61	/* R61H: Resolution settings */
54 #define PIXPAPER_CMD_GATE_SOURCE_START 0x65	/* R65H: Gate/source start */
55 #define PIXPAPER_CMD_UNKNOWN_B4 0xB4		/* RB4H: Unknown command */
56 #define PIXPAPER_CMD_UNKNOWN_B5 0xB5		/* RB5H: Unknown command */
57 #define PIXPAPER_CMD_UNKNOWN_E0 0xE0		/* RE0H: Unknown command */
58 #define PIXPAPER_CMD_POWER_SAVING 0xE3		/* RE3H: Power saving */
59 #define PIXPAPER_CMD_UNKNOWN_E7 0xE7		/* RE7H: Unknown command */
60 #define PIXPAPER_CMD_UNKNOWN_E9 0xE9		/* RE9H: Unknown command */
61 
62 /* R00H PSR - First Parameter */
63 #define PIXPAPER_PSR_RST_N BIT(0)
64 /* Bit 0: RST_N, 1=no effect (default), 0=reset with booster OFF */
65 #define PIXPAPER_PSR_SHD_N BIT(1)
66 /* Bit 1: SHD_N, 1=booster ON (default), 0=booster OFF */
67 #define PIXPAPER_PSR_SHL BIT(2)
68 /* Bit 2: SHL, 1=shift right (default), 0=shift left */
69 #define PIXPAPER_PSR_UD BIT(3)
70 /* Bit 3: UD, 1=scan up (default), 0=scan down */
71 #define PIXPAPER_PSR_PST_MODE BIT(5)
72 /* Bit 5: PST_MODE, 0=frame scanning (default), 1=external */
73 #define PIXPAPER_PSR_RES_MASK (3 << 6)
74 /* Bits 7-6: RES[1:0], resolution setting */
75 #define PIXPAPER_PSR_RES_176x296 (0x0 << 6)	/* 00: 176x296 */
76 #define PIXPAPER_PSR_RES_128x296 (0x1 << 6)	/* 01: 128x296 */
77 #define PIXPAPER_PSR_RES_128x250 (0x2 << 6)	/* 10: 128x250 */
78 #define PIXPAPER_PSR_RES_112x204 (0x3 << 6)	/* 11: 112x204 */
79 #define PIXPAPER_PSR_CONFIG                                           \
80 	(PIXPAPER_PSR_RST_N | PIXPAPER_PSR_SHD_N | PIXPAPER_PSR_SHL | \
81 	 PIXPAPER_PSR_UD)
82 /* 0x0F: Default settings, resolution set by R61H */
83 
84 /* R00H PSR - Second Parameter */
85 #define PIXPAPER_PSR2_VC_LUTZ \
86 	(1 << 0) /* Bit 0: VC_LUTZ, 1=VCOM float after refresh (default), 0=no effect */
87 #define PIXPAPER_PSR2_NORG \
88 	(1 << 1) /* Bit 1: NORG, 1=VCOM to GND before power off, 0=no effect (default) */
89 #define PIXPAPER_PSR2_TIEG \
90 	(1 << 2) /* Bit 2: TIEG, 1=VGN to GND on power off, 0=no effect (default) */
91 #define PIXPAPER_PSR2_TS_AUTO \
92 	(1 << 3) /* Bit 3: TS_AUTO, 1=sensor on RST_N low to high (default), 0=on booster */
93 #define PIXPAPER_PSR2_VCMZ \
94 	(1 << 4) /* Bit 4: VCMZ, 1=VCOM always floating, 0=no effect (default) */
95 #define PIXPAPER_PSR2_FOPT \
96 	(1 << 5) /* Bit 5: FOPT, 0=scan 1 frame (default), 1=no scan, HiZ */
97 #define PIXPAPER_PSR_CONFIG2     \
98 	(PIXPAPER_PSR2_VC_LUTZ | \
99 	 PIXPAPER_PSR2_TS_AUTO) /* 0x09: Default VCOM and temp sensor settings */
100 
101 /* R01H PWR - Power Setting Register */
102 /* First Parameter */
103 #define PIXPAPER_PWR_VDG_EN \
104 	(1 << 0) /* Bit 0: VDG_EN, 1=internal DCDC for VGP/VGN (default), 0=external */
105 #define PIXPAPER_PWR_VDS_EN \
106 	(1 << 1) /* Bit 1: VDS_EN, 1=internal regulator for VSP/VSN (default), 0=external */
107 #define PIXPAPER_PWR_VSC_EN \
108 	(1 << 2) /* Bit 2: VSC_EN, 1=internal regulator for VSPL (default), 0=external */
109 #define PIXPAPER_PWR_V_MODE \
110 	(1 << 3) /* Bit 3: V_MODE, 0=Mode0 (default), 1=Mode1 */
111 #define PIXPAPER_PWR_CONFIG1                         \
112 	(PIXPAPER_PWR_VDG_EN | PIXPAPER_PWR_VDS_EN | \
113 	 PIXPAPER_PWR_VSC_EN) /* 0x07: Internal power for VGP/VGN, VSP/VSN, VSPL */
114 
115 /* Second Parameter */
116 #define PIXPAPER_PWR_VGPN_MASK \
117 	(3 << 0) /* Bits 1-0: VGPN, VGP/VGN voltage levels */
118 #define PIXPAPER_PWR_VGPN_20V (0x0 << 0) /* 00: VGP=20V, VGN=-20V (default) */
119 #define PIXPAPER_PWR_VGPN_17V (0x1 << 0) /* 01: VGP=17V, VGN=-17V */
120 #define PIXPAPER_PWR_VGPN_15V (0x2 << 0) /* 10: VGP=15V, VGN=-15V */
121 #define PIXPAPER_PWR_VGPN_10V (0x3 << 0) /* 11: VGP=10V, VGN=-10V */
122 #define PIXPAPER_PWR_CONFIG2 PIXPAPER_PWR_VGPN_20V /* 0x00: VGP=20V, VGN=-20V */
123 
124 /* Third, Fourth, Sixth Parameters (VSP_1, VSPL_0, VSPL_1) */
125 #define PIXPAPER_PWR_VSP_8_2V 0x22 /* VSP_1/VSPL_1: 8.2V (34 decimal) */
126 #define PIXPAPER_PWR_VSPL_15V 0x78 /* VSPL_0: 15V (120 decimal) */
127 
128 /* Fifth Parameter (VSN_1) */
129 #define PIXPAPER_PWR_VSN_4V 0x0A /* VSN_1: -4V (10 decimal) */
130 
131 /* R03H PFS - Power Off Sequence Setting Register */
132 /* First Parameter */
133 #define PIXPAPER_PFS_T_VDS_OFF_MASK \
134 	(3 << 0) /* Bits 1-0: T_VDS_OFF, VSP/VSN power-off sequence */
135 #define PIXPAPER_PFS_T_VDS_OFF_20MS (0x0 << 0) /* 00: 20 ms (default) */
136 #define PIXPAPER_PFS_T_VDS_OFF_40MS (0x1 << 0) /* 01: 40 ms */
137 #define PIXPAPER_PFS_T_VDS_OFF_60MS (0x2 << 0) /* 10: 60 ms */
138 #define PIXPAPER_PFS_T_VDS_OFF_80MS (0x3 << 0) /* 11: 80 ms */
139 #define PIXPAPER_PFS_T_VDPG_OFF_MASK \
140 	(3 << 4) /* Bits 5-4: T_VDPG_OFF, VGP/VGN power-off sequence */
141 #define PIXPAPER_PFS_T_VDPG_OFF_20MS (0x0 << 4) /* 00: 20 ms (default) */
142 #define PIXPAPER_PFS_T_VDPG_OFF_40MS (0x1 << 4) /* 01: 40 ms */
143 #define PIXPAPER_PFS_T_VDPG_OFF_60MS (0x2 << 4) /* 10: 60 ms */
144 #define PIXPAPER_PFS_T_VDPG_OFF_80MS (0x3 << 4) /* 11: 80 ms */
145 #define PIXPAPER_PFS_CONFIG1           \
146 	(PIXPAPER_PFS_T_VDS_OFF_20MS | \
147 	 PIXPAPER_PFS_T_VDPG_OFF_20MS) /* 0x10: Default 20 ms for VSP/VSN and VGP/VGN */
148 
149 /* Second Parameter */
150 #define PIXPAPER_PFS_VGP_EXT_MASK \
151 	(0xF << 0) /* Bits 3-0: VGP_EXT, VGP extension time */
152 #define PIXPAPER_PFS_VGP_EXT_0MS (0x0 << 0) /* 0000: 0 ms */
153 #define PIXPAPER_PFS_VGP_EXT_500MS (0x1 << 0) /* 0001: 500 ms */
154 #define PIXPAPER_PFS_VGP_EXT_1000MS (0x2 << 0) /* 0010: 1000 ms */
155 #define PIXPAPER_PFS_VGP_EXT_1500MS (0x3 << 0) /* 0011: 1500 ms */
156 #define PIXPAPER_PFS_VGP_EXT_2000MS (0x4 << 0) /* 0100: 2000 ms (default) */
157 #define PIXPAPER_PFS_VGP_EXT_2500MS (0x5 << 0) /* 0101: 2500 ms */
158 #define PIXPAPER_PFS_VGP_EXT_3000MS (0x6 << 0) /* 0110: 3000 ms */
159 #define PIXPAPER_PFS_VGP_EXT_3500MS (0x7 << 0) /* 0111: 3500 ms */
160 #define PIXPAPER_PFS_VGP_EXT_4000MS (0x8 << 0) /* 1000: 4000 ms */
161 #define PIXPAPER_PFS_VGP_EXT_4500MS (0x9 << 0) /* 1001: 4500 ms */
162 #define PIXPAPER_PFS_VGP_EXT_5000MS (0xA << 0) /* 1010: 5000 ms */
163 #define PIXPAPER_PFS_VGP_EXT_5500MS (0xB << 0) /* 1011: 5500 ms */
164 #define PIXPAPER_PFS_VGP_EXT_6000MS (0xC << 0) /* 1100: 6000 ms */
165 #define PIXPAPER_PFS_VGP_EXT_6500MS (0xD << 0) /* 1101: 6500 ms */
166 #define PIXPAPER_PFS_VGP_LEN_MASK \
167 	(0xF << 4) /* Bits 7-4: VGP_LEN, VGP at 10V during power-off */
168 #define PIXPAPER_PFS_VGP_LEN_0MS (0x0 << 4) /* 0000: 0 ms */
169 #define PIXPAPER_PFS_VGP_LEN_500MS (0x1 << 4) /* 0001: 500 ms */
170 #define PIXPAPER_PFS_VGP_LEN_1000MS (0x2 << 4) /* 0010: 1000 ms */
171 #define PIXPAPER_PFS_VGP_LEN_1500MS (0x3 << 4) /* 0011: 1500 ms */
172 #define PIXPAPER_PFS_VGP_LEN_2000MS (0x4 << 4) /* 0100: 2000 ms */
173 #define PIXPAPER_PFS_VGP_LEN_2500MS (0x5 << 4) /* 0101: 2500 ms (default) */
174 #define PIXPAPER_PFS_VGP_LEN_3000MS (0x6 << 4) /* 0110: 3000 ms */
175 #define PIXPAPER_PFS_VGP_LEN_3500MS (0x7 << 4) /* 0111: 3500 ms */
176 #define PIXPAPER_PFS_VGP_LEN_4000MS (0x8 << 4) /* 1000: 4000 ms */
177 #define PIXPAPER_PFS_VGP_LEN_4500MS (0x9 << 4) /* 1001: 4500 ms */
178 #define PIXPAPER_PFS_VGP_LEN_5000MS (0xA << 4) /* 1010: 5000 ms */
179 #define PIXPAPER_PFS_VGP_LEN_5500MS (0xB << 4) /* 1011: 5500 ms */
180 #define PIXPAPER_PFS_VGP_LEN_6000MS (0xC << 4) /* 1100: 6000 ms */
181 #define PIXPAPER_PFS_VGP_LEN_6500MS (0xD << 4) /* 1101: 6500 ms */
182 #define PIXPAPER_PFS_CONFIG2           \
183 	(PIXPAPER_PFS_VGP_EXT_1000MS | \
184 	 PIXPAPER_PFS_VGP_LEN_2500MS) /* 0x54: VGP extension 1000 ms, VGP at 10V for 2500 ms */
185 
186 /* Third Parameter */
187 #define PIXPAPER_PFS_XON_LEN_MASK \
188 	(0xF << 0) /* Bits 3-0: XON_LEN, XON enable time */
189 #define PIXPAPER_PFS_XON_LEN_0MS (0x0 << 0) /* 0000: 0 ms */
190 #define PIXPAPER_PFS_XON_LEN_500MS (0x1 << 0) /* 0001: 500 ms */
191 #define PIXPAPER_PFS_XON_LEN_1000MS (0x2 << 0) /* 0010: 1000 ms */
192 #define PIXPAPER_PFS_XON_LEN_1500MS (0x3 << 0) /* 0011: 1500 ms */
193 #define PIXPAPER_PFS_XON_LEN_2000MS (0x4 << 0) /* 0100: 2000 ms (default) */
194 #define PIXPAPER_PFS_XON_LEN_2500MS (0x5 << 0) /* 0101: 2500 ms */
195 #define PIXPAPER_PFS_XON_LEN_3000MS (0x6 << 0) /* 0110: 3000 ms */
196 #define PIXPAPER_PFS_XON_LEN_3500MS (0x7 << 0) /* 0111: 3500 ms */
197 #define PIXPAPER_PFS_XON_LEN_4000MS (0x8 << 0) /* 1000: 4000 ms */
198 #define PIXPAPER_PFS_XON_LEN_4500MS (0x9 << 0) /* 1001: 4500 ms */
199 #define PIXPAPER_PFS_XON_LEN_5000MS (0xA << 0) /* 1010: 5000 ms */
200 #define PIXPAPER_PFS_XON_LEN_5500MS (0xB << 0) /* 1011: 5500 ms */
201 #define PIXPAPER_PFS_XON_LEN_6000MS (0xC << 0) /* 1100: 6000 ms */
202 #define PIXPAPER_PFS_XON_DLY_MASK \
203 	(0xF << 4) /* Bits 7-4: XON_DLY, XON delay time */
204 #define PIXPAPER_PFS_XON_DLY_0MS (0x0 << 4) /* 0000: 0 ms */
205 #define PIXPAPER_PFS_XON_DLY_500MS (0x1 << 4) /* 0001: 500 ms */
206 #define PIXPAPER_PFS_XON_DLY_1000MS (0x2 << 4) /* 0010: 1000 ms */
207 #define PIXPAPER_PFS_XON_DLY_1500MS (0x3 << 4) /* 0011: 1500 ms */
208 #define PIXPAPER_PFS_XON_DLY_2000MS (0x4 << 4) /* 0100: 2000 ms (default) */
209 #define PIXPAPER_PFS_XON_DLY_2500MS (0x5 << 4) /* 0101: 2500 ms */
210 #define PIXPAPER_PFS_XON_DLY_3000MS (0x6 << 4) /* 0110: 3000 ms */
211 #define PIXPAPER_PFS_XON_DLY_3500MS (0x7 << 4) /* 0111: 3500 ms */
212 #define PIXPAPER_PFS_XON_DLY_4000MS (0x8 << 4) /* 1000: 4000 ms */
213 #define PIXPAPER_PFS_XON_DLY_4500MS (0x9 << 4) /* 1001: 4500 ms */
214 #define PIXPAPER_PFS_XON_DLY_5000MS (0xA << 4) /* 1010: 5000 ms */
215 #define PIXPAPER_PFS_XON_DLY_5500MS (0xB << 4) /* 1011: 5500 ms */
216 #define PIXPAPER_PFS_XON_DLY_6000MS (0xC << 4) /* 1100: 6000 ms */
217 #define PIXPAPER_PFS_CONFIG3           \
218 	(PIXPAPER_PFS_XON_LEN_2000MS | \
219 	 PIXPAPER_PFS_XON_DLY_2000MS) /* 0x44: XON enable and delay at 2000 ms */
220 
221 /* R06H BTST - Booster Soft Start Command */
222 /* First Parameter */
223 #define PIXPAPER_BTST_PHA_SFT_MASK \
224 	(3 << 0) /* Bits 1-0: PHA_SFT, soft start period for phase A */
225 #define PIXPAPER_BTST_PHA_SFT_10MS (0x0 << 0) /* 00: 10 ms (default) */
226 #define PIXPAPER_BTST_PHA_SFT_20MS (0x1 << 0) /* 01: 20 ms */
227 #define PIXPAPER_BTST_PHA_SFT_30MS (0x2 << 0) /* 10: 30 ms */
228 #define PIXPAPER_BTST_PHA_SFT_40MS (0x3 << 0) /* 11: 40 ms */
229 #define PIXPAPER_BTST_PHB_SFT_MASK \
230 	(3 << 2) /* Bits 3-2: PHB_SFT, soft start period for phase B */
231 #define PIXPAPER_BTST_PHB_SFT_10MS (0x0 << 2) /* 00: 10 ms (default) */
232 #define PIXPAPER_BTST_PHB_SFT_20MS (0x1 << 2) /* 01: 20 ms */
233 #define PIXPAPER_BTST_PHB_SFT_30MS (0x2 << 2) /* 10: 30 ms */
234 #define PIXPAPER_BTST_PHB_SFT_40MS (0x3 << 2) /* 11: 40 ms */
235 #define PIXPAPER_BTST_CONFIG1         \
236 	(PIXPAPER_BTST_PHA_SFT_40MS | \
237 	 PIXPAPER_BTST_PHB_SFT_40MS) /* 0x0F: 40 ms for phase A and B */
238 
239 /* Second to Seventh Parameters (Driving Strength or Minimum OFF Time) */
240 #define PIXPAPER_BTST_CONFIG2 0x0A /* Strength11 */
241 #define PIXPAPER_BTST_CONFIG3 0x2F /* Period48 */
242 #define PIXPAPER_BTST_CONFIG4 0x25 /* Strength38 */
243 #define PIXPAPER_BTST_CONFIG5 0x22 /* Period35 */
244 #define PIXPAPER_BTST_CONFIG6 0x2E /* Strength47 */
245 #define PIXPAPER_BTST_CONFIG7 0x21 /* Period34 */
246 
247 /* R12H: DRF (Display Refresh) */
248 #define PIXPAPER_DRF_VCOM_AC 0x00 /* AC VCOM: VCOM follows LUTC (default) */
249 #define PIXPAPER_DRF_VCOM_DC 0x01 /* DC VCOM: VCOM fixed to VCOMDC */
250 
251 /* R30H PLL - PLL Control Register */
252 /* First Parameter */
253 #define PIXPAPER_PLL_FR_MASK (0x7 << 0) /* Bits 2-0: FR, frame rate */
254 #define PIXPAPER_PLL_FR_12_5HZ (0x0 << 0) /* 000: 12.5 Hz */
255 #define PIXPAPER_PLL_FR_25HZ (0x1 << 0)	/* 001: 25 Hz */
256 #define PIXPAPER_PLL_FR_50HZ (0x2 << 0) /* 010: 50 Hz (default) */
257 #define PIXPAPER_PLL_FR_65HZ (0x3 << 0) /* 011: 65 Hz */
258 #define PIXPAPER_PLL_FR_75HZ (0x4 << 0) /* 100: 75 Hz */
259 #define PIXPAPER_PLL_FR_85HZ (0x5 << 0) /* 101: 85 Hz */
260 #define PIXPAPER_PLL_FR_100HZ (0x6 << 0) /* 110: 100 Hz */
261 #define PIXPAPER_PLL_FR_120HZ (0x7 << 0) /* 111: 120 Hz */
262 #define PIXPAPER_PLL_DFR \
263 	(1 << 3) /* Bit 3: Dynamic frame rate, 0=disabled (default), 1=enabled */
264 #define PIXPAPER_PLL_CONFIG \
265 	(PIXPAPER_PLL_FR_50HZ) /* 0x02: 50 Hz, dynamic frame rate disabled */
266 
267 /* R41H TSE - Temperature Sensor Calibration Register */
268 /* First Parameter */
269 #define PIXPAPER_TSE_TO_MASK \
270 	(0xF << 0) /* Bits 3-0: TO[3:0], temperature offset */
271 #define PIXPAPER_TSE_TO_POS_0C (0x0 << 0) /* 0000: +0°C (default) */
272 #define PIXPAPER_TSE_TO_POS_0_5C (0x1 << 0) /* 0001: +0.5°C */
273 #define PIXPAPER_TSE_TO_POS_1C (0x2 << 0) /* 0010: +1°C */
274 #define PIXPAPER_TSE_TO_POS_1_5C (0x3 << 0) /* 0011: +1.5°C */
275 #define PIXPAPER_TSE_TO_POS_2C (0x4 << 0) /* 0100: +2°C */
276 #define PIXPAPER_TSE_TO_POS_2_5C (0x5 << 0) /* 0101: +2.5°C */
277 #define PIXPAPER_TSE_TO_POS_3C (0x6 << 0) /* 0110: +3°C */
278 #define PIXPAPER_TSE_TO_POS_3_5C (0x7 << 0) /* 0111: +3.5°C */
279 #define PIXPAPER_TSE_TO_NEG_4C (0x8 << 0) /* 1000: -4°C */
280 #define PIXPAPER_TSE_TO_NEG_3_5C (0x9 << 0) /* 1001: -3.5°C */
281 #define PIXPAPER_TSE_TO_NEG_3C (0xA << 0) /* 1010: -3°C */
282 #define PIXPAPER_TSE_TO_NEG_2_5C (0xB << 0) /* 1011: -2.5°C */
283 #define PIXPAPER_TSE_TO_NEG_2C (0xC << 0) /* 1100: -2°C */
284 #define PIXPAPER_TSE_TO_NEG_1_5C (0xD << 0) /* 1101: -1.5°C */
285 #define PIXPAPER_TSE_TO_NEG_1C (0xE << 0) /* 1110: -1°C */
286 #define PIXPAPER_TSE_TO_NEG_0_5C (0xF << 0) /* 1111: -0.5°C */
287 #define PIXPAPER_TSE_TO_FINE_MASK \
288 	(0x3 << 4) /* Bits 5-4: TO[5:4], fine adjustment for positive offsets */
289 #define PIXPAPER_TSE_TO_FINE_0C (0x0 << 4) /* 00: +0.0°C (default) */
290 #define PIXPAPER_TSE_TO_FINE_0_25C (0x1 << 4) /* 01: +0.25°C */
291 #define PIXPAPER_TSE_ENABLE \
292 	(0 << 7) /* Bit 7: TSE, 0=internal sensor enabled (default), 1=disabled (external) */
293 #define PIXPAPER_TSE_DISABLE \
294 	(1 << 7) /* Bit 7: TSE, 1=internal sensor disabled, use external */
295 #define PIXPAPER_TSE_CONFIG                                 \
296 	(PIXPAPER_TSE_TO_POS_0C | PIXPAPER_TSE_TO_FINE_0C | \
297 	 PIXPAPER_TSE_ENABLE) /* 0x00: Internal sensor enabled, +0°C offset */
298 
299 /* R4DH */
300 #define PIXPAPER_UNKNOWN_4D_CONFIG \
301 	0x78 /* This value is essential for initialization, derived from userspace examples. */
302 
303 /* R50H CDI - VCOM and DATA Interval Setting Register */
304 /* First Parameter */
305 #define PIXPAPER_CDI_INTERVAL_MASK \
306 	(0xF << 0) /* Bits 3-0: CDI[3:0], VCOM and data interval (hsync) */
307 #define PIXPAPER_CDI_17_HSYNC (0x0 << 0) /* 0000: 17 hsync */
308 #define PIXPAPER_CDI_16_HSYNC (0x1 << 0) /* 0001: 16 hsync */
309 #define PIXPAPER_CDI_15_HSYNC (0x2 << 0) /* 0010: 15 hsync */
310 #define PIXPAPER_CDI_14_HSYNC (0x3 << 0) /* 0011: 14 hsync */
311 #define PIXPAPER_CDI_13_HSYNC (0x4 << 0) /* 0100: 13 hsync */
312 #define PIXPAPER_CDI_12_HSYNC (0x5 << 0) /* 0101: 12 hsync */
313 #define PIXPAPER_CDI_11_HSYNC (0x6 << 0) /* 0110: 11 hsync */
314 #define PIXPAPER_CDI_10_HSYNC (0x7 << 0) /* 0111: 10 hsync (default) */
315 #define PIXPAPER_CDI_9_HSYNC (0x8 << 0) /* 1000: 9 hsync */
316 #define PIXPAPER_CDI_8_HSYNC (0x9 << 0) /* 1001: 8 hsync */
317 #define PIXPAPER_CDI_7_HSYNC (0xA << 0) /* 1010: 7 hsync */
318 #define PIXPAPER_CDI_6_HSYNC (0xB << 0) /* 1011: 6 hsync */
319 #define PIXPAPER_CDI_5_HSYNC (0xC << 0) /* 1100: 5 hsync */
320 #define PIXPAPER_CDI_4_HSYNC (0xD << 0) /* 1101: 4 hsync */
321 #define PIXPAPER_CDI_3_HSYNC (0xE << 0) /* 1110: 3 hsync */
322 #define PIXPAPER_CDI_2_HSYNC (0xF << 0) /* 1111: 2 hsync */
323 #define PIXPAPER_CDI_DDX \
324 	(1 << 4) /* Bit 4: DDX, 0=grayscale mapping 0, 1=grayscale mapping 1 (default) */
325 #define PIXPAPER_CDI_VBD_MASK \
326 	(0x7 << 5) /* Bits 7-5: VBD[2:0], border data selection */
327 #define PIXPAPER_CDI_VBD_FLOAT (0x0 << 5) /* 000: Floating (DDX=0 or 1) */
328 #define PIXPAPER_CDI_VBD_GRAY3_DDX0 \
329 	(0x1 << 5) /* 001: Gray3 (border_buf=011) when DDX=0 */
330 #define PIXPAPER_CDI_VBD_GRAY2_DDX0 \
331 	(0x2 << 5) /* 010: Gray2 (border_buf=010) when DDX=0 */
332 #define PIXPAPER_CDI_VBD_GRAY1_DDX0 \
333 	(0x3 << 5) /* 011: Gray1 (border_buf=001) when DDX=0 */
334 #define PIXPAPER_CDI_VBD_GRAY0_DDX0 \
335 	(0x4 << 5) /* 100: Gray0 (border_buf=000) when DDX=0 */
336 #define PIXPAPER_CDI_VBD_GRAY0_DDX1 \
337 	(0x0 << 5) /* 000: Gray0 (border_buf=000) when DDX=1 */
338 #define PIXPAPER_CDI_VBD_GRAY1_DDX1 \
339 	(0x1 << 5) /* 001: Gray1 (border_buf=001) when DDX=1 */
340 #define PIXPAPER_CDI_VBD_GRAY2_DDX1 \
341 	(0x2 << 5) /* 010: Gray2 (border_buf=010) when DDX=1 */
342 #define PIXPAPER_CDI_VBD_GRAY3_DDX1 \
343 	(0x3 << 5) /* 011: Gray3 (border_buf=011) when DDX=1 */
344 #define PIXPAPER_CDI_VBD_FLOAT_DDX1 (0x4 << 5) /* 100: Floating when DDX=1 */
345 #define PIXPAPER_CDI_CONFIG                         \
346 	(PIXPAPER_CDI_10_HSYNC | PIXPAPER_CDI_DDX | \
347 	 PIXPAPER_CDI_VBD_GRAY1_DDX1) /* 0x37: 10 hsync, DDX=1, border Gray1 */
348 
349 /* R60H */
350 #define PIXPAPER_UNKNOWN_60_CONFIG1 \
351 	0x02 /* This value is essential for initialization, derived from userspace examples. */
352 #define PIXPAPER_UNKNOWN_60_CONFIG2 \
353 	0x02 /* This value is essential for initialization, derived from userspace examples. */
354 
355 /* R61H TRES - Resolution Setting Register */
356 #define PIXPAPER_TRES_HRES_H                  \
357 	((PIXPAPER_PANEL_BUFFER_WIDTH >> 8) & \
358 	 0xFF) /* HRES[9:8]: High byte of horizontal resolution (128) */
359 #define PIXPAPER_TRES_HRES_L           \
360 	(PIXPAPER_PANEL_BUFFER_WIDTH & \
361 	 0xFF) /* HRES[7:0]: Low byte of horizontal resolution (128 = 0x80) */
362 #define PIXPAPER_TRES_VRES_H      \
363 	((PIXPAPER_HEIGHT >> 8) & \
364 	 0xFF) /* VRES[9:8]: High byte of vertical resolution (250) */
365 #define PIXPAPER_TRES_VRES_L \
366 	(PIXPAPER_HEIGHT &   \
367 	 0xFF) /* VRES[7:0]: Low byte of vertical resolution (250 = 0xFA) */
368 
369 /* R65H GSST - Gate/Source Start Setting Register */
370 #define PIXPAPER_GSST_S_START 0x00 /* S_Start[7:0]: First source line (S0) */
371 #define PIXPAPER_GSST_RESERVED 0x00 /* Reserved byte */
372 #define PIXPAPER_GSST_G_START_H \
373 	0x00 /* G_Start[8]: High bit of first gate line (G0) */
374 #define PIXPAPER_GSST_G_START_L \
375 	0x00 /* G_Start[7:0]: Low byte of first gate line (G0) */
376 
377 /* RB4H */
378 #define PIXPAPER_UNKNOWN_B4_CONFIG \
379 	0xD0 /* This value is essential for initialization, derived from userspace examples. */
380 
381 /* RB5H */
382 #define PIXPAPER_UNKNOWN_B5_CONFIG \
383 	0x03 /* This value is essential for initialization, derived from userspace examples. */
384 
385 /* RE0H */
386 #define PIXPAPER_UNKNOWN_E0_CONFIG \
387 	0x00 /* This value is essential for initialization, derived from userspace examples. */
388 
389 /* RE3H PWS - Power Saving Register */
390 /* First Parameter */
391 #define PIXPAPER_PWS_VCOM_W_MASK \
392 	(0xF                     \
393 	 << 4) /* Bits 7-4: VCOM_W[3:0], VCOM power-saving width (line periods) */
394 #define PIXPAPER_PWS_VCOM_W_0 (0x0 << 4) /* 0000: 0 line periods */
395 #define PIXPAPER_PWS_VCOM_W_1 (0x1 << 4) /* 0001: 1 line period */
396 #define PIXPAPER_PWS_VCOM_W_2 (0x2 << 4) /* 0010: 2 line periods */
397 #define PIXPAPER_PWS_VCOM_W_3 (0x3 << 4) /* 0011: 3 line periods */
398 #define PIXPAPER_PWS_VCOM_W_4 (0x4 << 4) /* 0100: 4 line periods */
399 #define PIXPAPER_PWS_VCOM_W_5 (0x5 << 4) /* 0101: 5 line periods */
400 #define PIXPAPER_PWS_VCOM_W_6 (0x6 << 4) /* 0110: 6 line periods */
401 #define PIXPAPER_PWS_VCOM_W_7 (0x7 << 4) /* 0111: 7 line periods */
402 #define PIXPAPER_PWS_VCOM_W_8 (0x8 << 4) /* 1000: 8 line periods */
403 #define PIXPAPER_PWS_VCOM_W_9 (0x9 << 4) /* 1001: 9 line periods */
404 #define PIXPAPER_PWS_VCOM_W_10 (0xA << 4) /* 1010: 10 line periods */
405 #define PIXPAPER_PWS_VCOM_W_11 (0xB << 4) /* 1011: 11 line periods */
406 #define PIXPAPER_PWS_VCOM_W_12 (0xC << 4) /* 1100: 12 line periods */
407 #define PIXPAPER_PWS_VCOM_W_13 (0xD << 4) /* 1101: 13 line periods */
408 #define PIXPAPER_PWS_VCOM_W_14 (0xE << 4) /* 1110: 14 line periods */
409 #define PIXPAPER_PWS_VCOM_W_15 (0xF << 4) /* 1111: 15 line periods */
410 #define PIXPAPER_PWS_SD_W_MASK \
411 	(0xF << 0) /* Bits 3-0: SD_W[3:0], source power-saving width (660 ns units) */
412 #define PIXPAPER_PWS_SD_W_0 (0x0 << 0) /* 0000: 0 ns */
413 #define PIXPAPER_PWS_SD_W_1 (0x1 << 0) /* 0001: 660 ns */
414 #define PIXPAPER_PWS_SD_W_2 (0x2 << 0) /* 0010: 1320 ns */
415 #define PIXPAPER_PWS_SD_W_3 (0x3 << 0) /* 0011: 1980 ns */
416 #define PIXPAPER_PWS_SD_W_4 (0x4 << 0) /* 0100: 2640 ns */
417 #define PIXPAPER_PWS_SD_W_5 (0x5 << 0) /* 0101: 3300 ns */
418 #define PIXPAPER_PWS_SD_W_6 (0x6 << 0) /* 0110: 3960 ns */
419 #define PIXPAPER_PWS_SD_W_7 (0x7 << 0) /* 0111: 4620 ns */
420 #define PIXPAPER_PWS_SD_W_8 (0x8 << 0) /* 1000: 5280 ns */
421 #define PIXPAPER_PWS_SD_W_9 (0x9 << 0) /* 1001: 5940 ns */
422 #define PIXPAPER_PWS_SD_W_10 (0xA << 0) /* 1010: 6600 ns */
423 #define PIXPAPER_PWS_SD_W_11 (0xB << 0) /* 1011: 7260 ns */
424 #define PIXPAPER_PWS_SD_W_12 (0xC << 0) /* 1100: 7920 ns */
425 #define PIXPAPER_PWS_SD_W_13 (0xD << 0) /* 1101: 8580 ns */
426 #define PIXPAPER_PWS_SD_W_14 (0xE << 0) /* 1110: 9240 ns */
427 #define PIXPAPER_PWS_SD_W_15 (0xF << 0) /* 1111: 9900 ns */
428 #define PIXPAPER_PWS_CONFIG      \
429 	(PIXPAPER_PWS_VCOM_W_2 | \
430 	 PIXPAPER_PWS_SD_W_2) /* 0x22: VCOM 2 line periods (160 µs), source 1320 ns */
431 
432 /* RE7H */
433 #define PIXPAPER_UNKNOWN_E7_CONFIG \
434 	0x1C /* This value is essential for initialization, derived from userspace examples. */
435 
436 /* RE9H */
437 #define PIXPAPER_UNKNOWN_E9_CONFIG \
438 	0x01 /* This value is essential for initialization, derived from userspace examples. */
439 
440 MODULE_IMPORT_NS("DMA_BUF");
441 
442 /*
443  * The panel has a visible resolution of 122x250.
444  * However, the controller requires the horizontal resolution to be aligned to 128 pixels.
445  * No porch or sync timing values are provided in the datasheet, so we define minimal
446  * placeholder values to satisfy the DRM framework.
447  */
448 
449 /* Panel visible resolution */
450 #define PIXPAPER_WIDTH           122
451 #define PIXPAPER_HEIGHT          250
452 
453 /* Controller requires 128 horizontal pixels total (for memory alignment) */
454 #define PIXPAPER_HTOTAL          128
455 #define PIXPAPER_HFP             2
456 #define PIXPAPER_HSYNC           2
457 #define PIXPAPER_HBP             (PIXPAPER_HTOTAL - PIXPAPER_WIDTH - PIXPAPER_HFP - PIXPAPER_HSYNC)
458 
459 /*
460  * According to the datasheet, the total vertical blanking must be 55 lines,
461  * regardless of how the vertical back porch is set.
462  * Here we allocate VFP=2, VSYNC=2, and VBP=51 to sum up to 55 lines.
463  * Total vertical lines = 250 (visible) + 55 (blanking) = 305.
464  */
465 #define PIXPAPER_VTOTAL  (250 + 55)
466 #define PIXPAPER_VFP     2
467 #define PIXPAPER_VSYNC   2
468 #define PIXPAPER_VBP     (55 - PIXPAPER_VFP - PIXPAPER_VSYNC)
469 
470 /*
471  * Pixel clock calculation:
472  * pixel_clock = htotal * vtotal * refresh_rate
473  *             = 128 * 305 * 50
474  *             = 1,952,000 Hz = 1952 kHz
475  */
476 #define PIXPAPER_PIXEL_CLOCK     1952
477 
478 #define PIXPAPER_WIDTH_MM        24    /* approximate from 23.7046mm */
479 #define PIXPAPER_HEIGHT_MM       49    /* approximate from 48.55mm */
480 
481 #define PIXPAPER_SPI_BITS_PER_WORD	8
482 #define PIXPAPER_SPI_SPEED_DEFAULT      1000000
483 
484 #define PIXPAPER_PANEL_BUFFER_WIDTH	128
485 #define PIXPAPER_PANEL_BUFFER_TWO_BYTES_PER_ROW (PIXPAPER_PANEL_BUFFER_WIDTH / 4)
486 
487 #define PIXPAPER_COLOR_THRESHOLD_LOW_CHANNEL		60
488 #define PIXPAPER_COLOR_THRESHOLD_HIGH_CHANNEL		200
489 #define PIXPAPER_COLOR_THRESHOLD_YELLOW_MIN_GREEN	180
490 
491 struct pixpaper_error_ctx {
492 	int errno_code;
493 };
494 
495 struct pixpaper_panel {
496 	struct drm_device drm;
497 	struct drm_plane plane;
498 	struct drm_crtc crtc;
499 	struct drm_encoder encoder;
500 	struct drm_connector connector;
501 
502 	struct spi_device *spi;
503 	struct gpio_desc *reset;
504 	struct gpio_desc *busy;
505 	struct gpio_desc *dc;
506 };
507 
508 static inline struct pixpaper_panel *to_pixpaper_panel(struct drm_device *drm)
509 {
510 	return container_of(drm, struct pixpaper_panel, drm);
511 }
512 
513 static void pixpaper_wait_for_panel(struct pixpaper_panel *panel)
514 {
515 	unsigned int timeout_ms = 10000;
516 	unsigned long timeout_jiffies = jiffies + msecs_to_jiffies(timeout_ms);
517 
518 	usleep_range(1000, 1500);
519 	while (gpiod_get_value_cansleep(panel->busy) != 1) {
520 		if (time_after(jiffies, timeout_jiffies)) {
521 			drm_warn(&panel->drm, "Busy wait timed out\n");
522 			return;
523 		}
524 		usleep_range(100, 200);
525 	}
526 }
527 
528 static void pixpaper_spi_sync(struct spi_device *spi, struct spi_message *msg,
529 			      struct pixpaper_error_ctx *err)
530 {
531 	if (err->errno_code)
532 		return;
533 
534 	int ret = spi_sync(spi, msg);
535 
536 	if (ret < 0)
537 		err->errno_code = ret;
538 }
539 
540 static void pixpaper_send_cmd(struct pixpaper_panel *panel, u8 cmd,
541 			      struct pixpaper_error_ctx *err)
542 {
543 	if (err->errno_code)
544 		return;
545 
546 	struct spi_transfer xfer = {
547 		.tx_buf = &cmd,
548 		.len = 1,
549 	};
550 	struct spi_message msg;
551 
552 	spi_message_init(&msg);
553 	spi_message_add_tail(&xfer, &msg);
554 
555 	gpiod_set_value_cansleep(panel->dc, 0);
556 	usleep_range(1, 5);
557 	pixpaper_spi_sync(panel->spi, &msg, err);
558 }
559 
560 static void pixpaper_send_data(struct pixpaper_panel *panel, u8 data,
561 			       struct pixpaper_error_ctx *err)
562 {
563 	if (err->errno_code)
564 		return;
565 
566 	struct spi_transfer xfer = {
567 		.tx_buf = &data,
568 		.len = 1,
569 	};
570 	struct spi_message msg;
571 
572 	spi_message_init(&msg);
573 	spi_message_add_tail(&xfer, &msg);
574 
575 	gpiod_set_value_cansleep(panel->dc, 1);
576 	usleep_range(1, 5);
577 	pixpaper_spi_sync(panel->spi, &msg, err);
578 }
579 
580 static int pixpaper_panel_hw_init(struct pixpaper_panel *panel)
581 {
582 	struct pixpaper_error_ctx err = { .errno_code = 0 };
583 
584 	gpiod_set_value_cansleep(panel->reset, 0);
585 	msleep(50);
586 	gpiod_set_value_cansleep(panel->reset, 1);
587 	msleep(50);
588 
589 	pixpaper_wait_for_panel(panel);
590 
591 	pixpaper_send_cmd(panel, PIXPAPER_CMD_UNKNOWN_4D, &err);
592 	pixpaper_send_data(panel, PIXPAPER_UNKNOWN_4D_CONFIG, &err);
593 	if (err.errno_code)
594 		goto init_fail;
595 	pixpaper_wait_for_panel(panel);
596 
597 	pixpaper_send_cmd(panel, PIXPAPER_CMD_PANEL_SETTING, &err);
598 	pixpaper_send_data(panel, PIXPAPER_PSR_CONFIG, &err);
599 	pixpaper_send_data(panel, PIXPAPER_PSR_CONFIG2, &err);
600 	if (err.errno_code)
601 		goto init_fail;
602 	pixpaper_wait_for_panel(panel);
603 
604 	pixpaper_send_cmd(panel, PIXPAPER_CMD_POWER_SETTING, &err);
605 	pixpaper_send_data(panel, PIXPAPER_PWR_CONFIG1, &err);
606 	pixpaper_send_data(panel, PIXPAPER_PWR_CONFIG2, &err);
607 	pixpaper_send_data(panel, PIXPAPER_PWR_VSP_8_2V, &err);
608 	pixpaper_send_data(panel, PIXPAPER_PWR_VSPL_15V, &err);
609 	pixpaper_send_data(panel, PIXPAPER_PWR_VSN_4V, &err);
610 	pixpaper_send_data(panel, PIXPAPER_PWR_VSP_8_2V, &err);
611 	if (err.errno_code)
612 		goto init_fail;
613 	pixpaper_wait_for_panel(panel);
614 
615 	pixpaper_send_cmd(panel, PIXPAPER_CMD_POWER_OFF_SEQUENCE, &err);
616 	pixpaper_send_data(panel, PIXPAPER_PFS_CONFIG1, &err);
617 	pixpaper_send_data(panel, PIXPAPER_PFS_CONFIG2, &err);
618 	pixpaper_send_data(panel, PIXPAPER_PFS_CONFIG3, &err);
619 	if (err.errno_code)
620 		goto init_fail;
621 	pixpaper_wait_for_panel(panel);
622 
623 	pixpaper_send_cmd(panel, PIXPAPER_CMD_BOOSTER_SOFT_START, &err);
624 	pixpaper_send_data(panel, PIXPAPER_BTST_CONFIG1, &err);
625 	pixpaper_send_data(panel, PIXPAPER_BTST_CONFIG2, &err);
626 	pixpaper_send_data(panel, PIXPAPER_BTST_CONFIG3, &err);
627 	pixpaper_send_data(panel, PIXPAPER_BTST_CONFIG4, &err);
628 	pixpaper_send_data(panel, PIXPAPER_BTST_CONFIG5, &err);
629 	pixpaper_send_data(panel, PIXPAPER_BTST_CONFIG6, &err);
630 	pixpaper_send_data(panel, PIXPAPER_BTST_CONFIG7, &err);
631 	if (err.errno_code)
632 		goto init_fail;
633 	pixpaper_wait_for_panel(panel);
634 
635 	pixpaper_send_cmd(panel, PIXPAPER_CMD_PLL_CONTROL, &err);
636 	pixpaper_send_data(panel, PIXPAPER_PLL_CONFIG, &err);
637 	if (err.errno_code)
638 		goto init_fail;
639 	pixpaper_wait_for_panel(panel);
640 
641 	pixpaper_send_cmd(panel, PIXPAPER_CMD_TEMP_SENSOR_CALIB, &err);
642 	pixpaper_send_data(panel, PIXPAPER_TSE_CONFIG, &err);
643 	if (err.errno_code)
644 		goto init_fail;
645 	pixpaper_wait_for_panel(panel);
646 
647 	pixpaper_send_cmd(panel, PIXPAPER_CMD_VCOM_INTERVAL, &err);
648 	pixpaper_send_data(panel, PIXPAPER_CDI_CONFIG, &err);
649 	if (err.errno_code)
650 		goto init_fail;
651 	pixpaper_wait_for_panel(panel);
652 
653 	pixpaper_send_cmd(panel, PIXPAPER_CMD_UNKNOWN_60, &err);
654 	pixpaper_send_data(panel, PIXPAPER_UNKNOWN_60_CONFIG1, &err);
655 	pixpaper_send_data(panel, PIXPAPER_UNKNOWN_60_CONFIG2, &err);
656 	if (err.errno_code)
657 		goto init_fail;
658 	pixpaper_wait_for_panel(panel);
659 
660 	pixpaper_send_cmd(panel, PIXPAPER_CMD_RESOLUTION_SETTING, &err);
661 	pixpaper_send_data(panel, PIXPAPER_TRES_HRES_H, &err);
662 	pixpaper_send_data(panel, PIXPAPER_TRES_HRES_L, &err);
663 	pixpaper_send_data(panel, PIXPAPER_TRES_VRES_H, &err);
664 	pixpaper_send_data(panel, PIXPAPER_TRES_VRES_L, &err);
665 	if (err.errno_code)
666 		goto init_fail;
667 	pixpaper_wait_for_panel(panel);
668 
669 	pixpaper_send_cmd(panel, PIXPAPER_CMD_GATE_SOURCE_START, &err);
670 	pixpaper_send_data(panel, PIXPAPER_GSST_S_START, &err);
671 	pixpaper_send_data(panel, PIXPAPER_GSST_RESERVED, &err);
672 	pixpaper_send_data(panel, PIXPAPER_GSST_G_START_H, &err);
673 	pixpaper_send_data(panel, PIXPAPER_GSST_G_START_L, &err);
674 	if (err.errno_code)
675 		goto init_fail;
676 	pixpaper_wait_for_panel(panel);
677 
678 	pixpaper_send_cmd(panel, PIXPAPER_CMD_UNKNOWN_E7, &err);
679 	pixpaper_send_data(panel, PIXPAPER_UNKNOWN_E7_CONFIG, &err);
680 	if (err.errno_code)
681 		goto init_fail;
682 	pixpaper_wait_for_panel(panel);
683 
684 	pixpaper_send_cmd(panel, PIXPAPER_CMD_POWER_SAVING, &err);
685 	pixpaper_send_data(panel, PIXPAPER_PWS_CONFIG, &err);
686 	if (err.errno_code)
687 		goto init_fail;
688 	pixpaper_wait_for_panel(panel);
689 
690 	pixpaper_send_cmd(panel, PIXPAPER_CMD_UNKNOWN_E0, &err);
691 	pixpaper_send_data(panel, PIXPAPER_UNKNOWN_E0_CONFIG, &err);
692 	if (err.errno_code)
693 		goto init_fail;
694 	pixpaper_wait_for_panel(panel);
695 
696 	pixpaper_send_cmd(panel, PIXPAPER_CMD_UNKNOWN_B4, &err);
697 	pixpaper_send_data(panel, PIXPAPER_UNKNOWN_B4_CONFIG, &err);
698 	if (err.errno_code)
699 		goto init_fail;
700 	pixpaper_wait_for_panel(panel);
701 
702 	pixpaper_send_cmd(panel, PIXPAPER_CMD_UNKNOWN_B5, &err);
703 	pixpaper_send_data(panel, PIXPAPER_UNKNOWN_B5_CONFIG, &err);
704 	if (err.errno_code)
705 		goto init_fail;
706 	pixpaper_wait_for_panel(panel);
707 
708 	pixpaper_send_cmd(panel, PIXPAPER_CMD_UNKNOWN_E9, &err);
709 	pixpaper_send_data(panel, PIXPAPER_UNKNOWN_E9_CONFIG, &err);
710 	if (err.errno_code)
711 		goto init_fail;
712 	pixpaper_wait_for_panel(panel);
713 
714 	return 0;
715 
716 init_fail:
717 	drm_err(&panel->drm, "Hardware initialization failed (err=%d)\n",
718 		err.errno_code);
719 	return err.errno_code;
720 }
721 
722 /*
723  * Convert framebuffer pixels to 2-bit e-paper format:
724  *   00 - White
725  *   01 - Black
726  *   10 - Yellow
727  *   11 - Red
728  */
729 static u8 pack_pixels_to_byte(__le32 *src_pixels, int i, int j,
730 			      struct drm_framebuffer *fb)
731 {
732 	u8 packed_byte = 0;
733 	int k;
734 
735 	for (k = 0; k < 4; k++) {
736 		int current_pixel_x = j * 4 + k;
737 		u8 two_bit_val;
738 
739 		if (current_pixel_x < PIXPAPER_WIDTH) {
740 			u32 pixel_offset =
741 				(i * (fb->pitches[0] / 4)) + current_pixel_x;
742 			u32 pixel = le32_to_cpu(src_pixels[pixel_offset]);
743 			u32 r = (pixel >> 16) & 0xFF;
744 			u32 g = (pixel >> 8) & 0xFF;
745 			u32 b = pixel & 0xFF;
746 
747 			if (r < PIXPAPER_COLOR_THRESHOLD_LOW_CHANNEL &&
748 			    g < PIXPAPER_COLOR_THRESHOLD_LOW_CHANNEL &&
749 			    b < PIXPAPER_COLOR_THRESHOLD_LOW_CHANNEL) {
750 				two_bit_val = 0b00;
751 			} else if (r > PIXPAPER_COLOR_THRESHOLD_HIGH_CHANNEL &&
752 				   g > PIXPAPER_COLOR_THRESHOLD_HIGH_CHANNEL &&
753 				   b > PIXPAPER_COLOR_THRESHOLD_HIGH_CHANNEL) {
754 				two_bit_val = 0b01;
755 			} else if (r > PIXPAPER_COLOR_THRESHOLD_HIGH_CHANNEL &&
756 				   g < PIXPAPER_COLOR_THRESHOLD_LOW_CHANNEL &&
757 				   b < PIXPAPER_COLOR_THRESHOLD_LOW_CHANNEL) {
758 				two_bit_val = 0b11;
759 			} else if (r > PIXPAPER_COLOR_THRESHOLD_HIGH_CHANNEL &&
760 				   g > PIXPAPER_COLOR_THRESHOLD_YELLOW_MIN_GREEN &&
761 				   b < PIXPAPER_COLOR_THRESHOLD_LOW_CHANNEL) {
762 				two_bit_val = 0b10;
763 			} else {
764 				two_bit_val = 0b01;
765 			}
766 		} else {
767 			two_bit_val = 0b01;
768 		}
769 
770 		packed_byte |= two_bit_val << ((3 - k) * 2);
771 	}
772 
773 	return packed_byte;
774 }
775 
776 static int pixpaper_plane_helper_atomic_check(struct drm_plane *plane,
777 					      struct drm_atomic_state *state)
778 {
779 	struct drm_plane_state *new_plane_state =
780 		drm_atomic_get_new_plane_state(state, plane);
781 	struct drm_crtc *new_crtc = new_plane_state->crtc;
782 	struct drm_crtc_state *new_crtc_state = NULL;
783 	int ret;
784 
785 	if (new_crtc)
786 		new_crtc_state = drm_atomic_get_new_crtc_state(state, new_crtc);
787 
788 	ret = drm_atomic_helper_check_plane_state(new_plane_state,
789 						  new_crtc_state, DRM_PLANE_NO_SCALING,
790 						  DRM_PLANE_NO_SCALING, false, false);
791 	if (ret)
792 		return ret;
793 	else if (!new_plane_state->visible)
794 		return 0;
795 
796 	return 0;
797 }
798 
799 static int pixpaper_crtc_helper_atomic_check(struct drm_crtc *crtc,
800 					     struct drm_atomic_state *state)
801 {
802 	struct drm_crtc_state *crtc_state =
803 		drm_atomic_get_new_crtc_state(state, crtc);
804 
805 	if (!crtc_state->enable)
806 		return 0;
807 
808 	return drm_atomic_helper_check_crtc_primary_plane(crtc_state);
809 }
810 
811 static void pixpaper_crtc_atomic_enable(struct drm_crtc *crtc,
812 					struct drm_atomic_state *state)
813 {
814 	struct pixpaper_panel *panel = to_pixpaper_panel(crtc->dev);
815 	struct drm_device *drm = &panel->drm;
816 	int idx;
817 	struct pixpaper_error_ctx err = { .errno_code = 0 };
818 
819 	if (!drm_dev_enter(drm, &idx))
820 		return;
821 
822 	pixpaper_send_cmd(panel, PIXPAPER_CMD_POWER_ON, &err);
823 	if (err.errno_code) {
824 		drm_err_once(drm, "Failed to send PON command: %d\n", err.errno_code);
825 		goto exit_drm_dev;
826 	}
827 
828 	pixpaper_wait_for_panel(panel);
829 
830 	drm_dbg(drm, "Panel enabled and powered on\n");
831 
832 exit_drm_dev:
833 	drm_dev_exit(idx);
834 }
835 
836 static void pixpaper_crtc_atomic_disable(struct drm_crtc *crtc,
837 					 struct drm_atomic_state *state)
838 {
839 	struct pixpaper_panel *panel = to_pixpaper_panel(crtc->dev);
840 	struct drm_device *drm = &panel->drm;
841 	struct pixpaper_error_ctx err = { .errno_code = 0 };
842 	int idx;
843 
844 	if (!drm_dev_enter(drm, &idx))
845 		return;
846 
847 	pixpaper_send_cmd(panel, PIXPAPER_CMD_POWER_OFF, &err);
848 	if (err.errno_code) {
849 		drm_err_once(drm, "Failed to send POF command: %d\n", err.errno_code);
850 		goto exit_drm_dev;
851 	}
852 	pixpaper_wait_for_panel(panel);
853 
854 	drm_dbg(drm, "Panel disabled\n");
855 
856 exit_drm_dev:
857 	drm_dev_exit(idx);
858 }
859 
860 static void pixpaper_plane_atomic_update(struct drm_plane *plane,
861 					 struct drm_atomic_state *state)
862 {
863 	struct drm_plane_state *plane_state =
864 		drm_atomic_get_new_plane_state(state, plane);
865 	struct drm_shadow_plane_state *shadow_plane_state =
866 		to_drm_shadow_plane_state(plane_state);
867 	struct drm_crtc *crtc = plane_state->crtc;
868 	struct pixpaper_panel *panel = to_pixpaper_panel(crtc->dev);
869 
870 	struct drm_device *drm = &panel->drm;
871 	struct drm_framebuffer *fb = plane_state->fb;
872 	struct iosys_map map = shadow_plane_state->data[0];
873 	void *vaddr = map.vaddr;
874 	int i, j, idx;
875 	__le32 *src_pixels = NULL;
876 	struct pixpaper_error_ctx err = { .errno_code = 0 };
877 
878 	if (!drm_dev_enter(drm, &idx))
879 		return;
880 
881 	drm_dbg(drm, "Starting frame update (phys=%dx%d, buf_w=%d)\n",
882 		PIXPAPER_WIDTH, PIXPAPER_HEIGHT, PIXPAPER_PANEL_BUFFER_WIDTH);
883 
884 	if (!fb || !plane_state->visible) {
885 		drm_err_once(drm, "No framebuffer or plane not visible, skipping update\n");
886 		goto update_cleanup;
887 	}
888 
889 	src_pixels = (__le32 *)vaddr;
890 
891 	pixpaper_send_cmd(panel, PIXPAPER_CMD_DATA_START_TRANSMISSION, &err);
892 	if (err.errno_code)
893 		goto update_cleanup;
894 
895 	pixpaper_wait_for_panel(panel);
896 
897 	for (i = 0; i < PIXPAPER_HEIGHT; i++) {
898 		for (j = 0; j < PIXPAPER_PANEL_BUFFER_TWO_BYTES_PER_ROW; j++) {
899 			u8 packed_byte =
900 				pack_pixels_to_byte(src_pixels, i, j, fb);
901 
902 			pixpaper_wait_for_panel(panel);
903 			pixpaper_send_data(panel, packed_byte, &err);
904 		}
905 	}
906 	pixpaper_wait_for_panel(panel);
907 
908 	pixpaper_send_cmd(panel, PIXPAPER_CMD_POWER_ON, &err);
909 	if (err.errno_code) {
910 		drm_err_once(drm, "Failed to send PON command: %d\n", err.errno_code);
911 		goto update_cleanup;
912 	}
913 	pixpaper_wait_for_panel(panel);
914 
915 	pixpaper_send_cmd(panel, PIXPAPER_CMD_DISPLAY_REFRESH, &err);
916 	pixpaper_send_data(panel, PIXPAPER_DRF_VCOM_AC, &err);
917 	if (err.errno_code) {
918 		drm_err_once(drm, "Failed sending data after DRF: %d\n", err.errno_code);
919 		goto update_cleanup;
920 	}
921 	pixpaper_wait_for_panel(panel);
922 
923 update_cleanup:
924 	if (err.errno_code && err.errno_code != -ETIMEDOUT)
925 		drm_err_once(drm, "Frame update function failed with error %d\n", err.errno_code);
926 
927 	drm_dev_exit(idx);
928 }
929 
930 static const struct drm_display_mode pixpaper_mode = {
931 	.clock = PIXPAPER_PIXEL_CLOCK,
932 	.hdisplay = PIXPAPER_WIDTH,
933 	.hsync_start = PIXPAPER_WIDTH + PIXPAPER_HFP,
934 	.hsync_end = PIXPAPER_WIDTH + PIXPAPER_HFP + PIXPAPER_HSYNC,
935 	.htotal = PIXPAPER_HTOTAL,
936 	.vdisplay = PIXPAPER_HEIGHT,
937 	.vsync_start = PIXPAPER_HEIGHT + PIXPAPER_VFP,
938 	.vsync_end = PIXPAPER_HEIGHT + PIXPAPER_VFP + PIXPAPER_VSYNC,
939 	.vtotal = PIXPAPER_VTOTAL,
940 	.width_mm = PIXPAPER_WIDTH_MM,
941 	.height_mm = PIXPAPER_HEIGHT_MM,
942 	.type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED,
943 };
944 
945 static int pixpaper_connector_get_modes(struct drm_connector *connector)
946 {
947 	return drm_connector_helper_get_modes_fixed(connector, &pixpaper_mode);
948 }
949 
950 static const struct drm_plane_funcs pixpaper_plane_funcs = {
951 	.update_plane = drm_atomic_helper_update_plane,
952 	.disable_plane = drm_atomic_helper_disable_plane,
953 	.destroy = drm_plane_cleanup,
954 	DRM_GEM_SHADOW_PLANE_FUNCS,
955 };
956 
957 static const struct drm_plane_helper_funcs pixpaper_plane_helper_funcs = {
958 	DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
959 	.atomic_check = pixpaper_plane_helper_atomic_check,
960 	.atomic_update = pixpaper_plane_atomic_update,
961 };
962 
963 static const struct drm_crtc_funcs pixpaper_crtc_funcs = {
964 	.set_config = drm_atomic_helper_set_config,
965 	.page_flip = drm_atomic_helper_page_flip,
966 	.reset = drm_atomic_helper_crtc_reset,
967 	.destroy = drm_crtc_cleanup,
968 	.atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
969 	.atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
970 };
971 
972 static enum drm_mode_status
973 pixpaper_mode_valid(struct drm_crtc *crtc, const struct drm_display_mode *mode)
974 {
975 	if (mode->hdisplay == PIXPAPER_WIDTH &&
976 	    mode->vdisplay == PIXPAPER_HEIGHT) {
977 		return MODE_OK;
978 	}
979 	return MODE_BAD;
980 }
981 
982 static const struct drm_crtc_helper_funcs pixpaper_crtc_helper_funcs = {
983 	.mode_valid = pixpaper_mode_valid,
984 	.atomic_check = pixpaper_crtc_helper_atomic_check,
985 	.atomic_enable = pixpaper_crtc_atomic_enable,
986 	.atomic_disable = pixpaper_crtc_atomic_disable,
987 };
988 
989 static const struct drm_encoder_funcs pixpaper_encoder_funcs = {
990 	.destroy = drm_encoder_cleanup,
991 };
992 
993 static const struct drm_connector_funcs pixpaper_connector_funcs = {
994 	.reset = drm_atomic_helper_connector_reset,
995 	.fill_modes = drm_helper_probe_single_connector_modes,
996 	.destroy = drm_connector_cleanup,
997 	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
998 	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
999 };
1000 
1001 static const struct drm_connector_helper_funcs pixpaper_connector_helper_funcs = {
1002 	.get_modes = pixpaper_connector_get_modes,
1003 };
1004 
1005 DEFINE_DRM_GEM_FOPS(pixpaper_fops);
1006 
1007 static struct drm_driver pixpaper_drm_driver = {
1008 	.driver_features = DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
1009 	.fops = &pixpaper_fops,
1010 	.name = "pixpaper",
1011 	.desc = "DRM driver for PIXPAPER e-ink",
1012 	.major = 1,
1013 	.minor = 0,
1014 	DRM_GEM_SHMEM_DRIVER_OPS,
1015 	DRM_FBDEV_SHMEM_DRIVER_OPS,
1016 };
1017 
1018 static const struct drm_mode_config_funcs pixpaper_mode_config_funcs = {
1019 	.fb_create = drm_gem_fb_create_with_dirty,
1020 	.atomic_check = drm_atomic_helper_check,
1021 	.atomic_commit = drm_atomic_helper_commit,
1022 };
1023 
1024 static int pixpaper_probe(struct spi_device *spi)
1025 {
1026 	struct device *dev = &spi->dev;
1027 	struct pixpaper_panel *panel;
1028 	struct drm_device *drm;
1029 	int ret;
1030 
1031 	panel = devm_drm_dev_alloc(dev, &pixpaper_drm_driver,
1032 				   struct pixpaper_panel, drm);
1033 	if (IS_ERR(panel))
1034 		return PTR_ERR(panel);
1035 
1036 	drm = &panel->drm;
1037 	panel->spi = spi;
1038 	spi_set_drvdata(spi, panel);
1039 
1040 	spi->mode = SPI_MODE_0;
1041 	spi->bits_per_word = PIXPAPER_SPI_BITS_PER_WORD;
1042 
1043 	if (!spi->max_speed_hz) {
1044 		drm_warn(drm,
1045 			 "spi-max-frequency not specified in DT, using default %u Hz\n",
1046 			 PIXPAPER_SPI_SPEED_DEFAULT);
1047 		spi->max_speed_hz = PIXPAPER_SPI_SPEED_DEFAULT;
1048 	}
1049 
1050 	ret = spi_setup(spi);
1051 	if (ret < 0) {
1052 		drm_err(drm, "SPI setup failed: %d\n", ret);
1053 		return ret;
1054 	}
1055 
1056 	if (!dev->dma_mask)
1057 		dev->dma_mask = &dev->coherent_dma_mask;
1058 	ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
1059 	if (ret) {
1060 		drm_err(drm, "Failed to set DMA mask: %d\n", ret);
1061 		return ret;
1062 	}
1063 
1064 	panel->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
1065 	if (IS_ERR(panel->reset))
1066 		return PTR_ERR(panel->reset);
1067 
1068 	panel->busy = devm_gpiod_get(dev, "busy", GPIOD_IN);
1069 	if (IS_ERR(panel->busy))
1070 		return PTR_ERR(panel->busy);
1071 
1072 	panel->dc = devm_gpiod_get(dev, "dc", GPIOD_OUT_HIGH);
1073 	if (IS_ERR(panel->dc))
1074 		return PTR_ERR(panel->dc);
1075 
1076 	ret = pixpaper_panel_hw_init(panel);
1077 	if (ret) {
1078 		drm_err(drm, "Panel hardware initialization failed: %d\n", ret);
1079 		return ret;
1080 	}
1081 
1082 	ret = drmm_mode_config_init(drm);
1083 	if (ret)
1084 		return ret;
1085 	drm->mode_config.funcs = &pixpaper_mode_config_funcs;
1086 	drm->mode_config.min_width = PIXPAPER_WIDTH;
1087 	drm->mode_config.max_width = PIXPAPER_WIDTH;
1088 	drm->mode_config.min_height = PIXPAPER_HEIGHT;
1089 	drm->mode_config.max_height = PIXPAPER_HEIGHT;
1090 
1091 	ret = drm_universal_plane_init(drm, &panel->plane, 1,
1092 				       &pixpaper_plane_funcs,
1093 				       (const uint32_t[]){ DRM_FORMAT_XRGB8888 },
1094 				       1, NULL, DRM_PLANE_TYPE_PRIMARY, NULL);
1095 	if (ret)
1096 		return ret;
1097 	drm_plane_helper_add(&panel->plane, &pixpaper_plane_helper_funcs);
1098 
1099 	ret = drm_crtc_init_with_planes(drm, &panel->crtc, &panel->plane, NULL,
1100 					&pixpaper_crtc_funcs, NULL);
1101 	if (ret)
1102 		return ret;
1103 	drm_crtc_helper_add(&panel->crtc, &pixpaper_crtc_helper_funcs);
1104 
1105 	ret = drm_encoder_init(drm, &panel->encoder, &pixpaper_encoder_funcs,
1106 			       DRM_MODE_ENCODER_NONE, NULL);
1107 	if (ret)
1108 		return ret;
1109 	panel->encoder.possible_crtcs = drm_crtc_mask(&panel->crtc);
1110 
1111 	ret = drm_connector_init(drm, &panel->connector,
1112 				 &pixpaper_connector_funcs,
1113 				 DRM_MODE_CONNECTOR_SPI);
1114 	if (ret)
1115 		return ret;
1116 
1117 	drm_connector_helper_add(&panel->connector,
1118 				 &pixpaper_connector_helper_funcs);
1119 	drm_connector_attach_encoder(&panel->connector, &panel->encoder);
1120 
1121 	drm_mode_config_reset(drm);
1122 
1123 	ret = drm_dev_register(drm, 0);
1124 	if (ret)
1125 		return ret;
1126 
1127 	drm_client_setup(drm, NULL);
1128 
1129 	return 0;
1130 }
1131 
1132 static void pixpaper_remove(struct spi_device *spi)
1133 {
1134 	struct pixpaper_panel *panel = spi_get_drvdata(spi);
1135 
1136 	if (!panel)
1137 		return;
1138 
1139 	drm_dev_unplug(&panel->drm);
1140 	drm_atomic_helper_shutdown(&panel->drm);
1141 }
1142 
1143 static const struct spi_device_id pixpaper_ids[] = { { "pixpaper", 0 }, {} };
1144 MODULE_DEVICE_TABLE(spi, pixpaper_ids);
1145 
1146 static const struct of_device_id pixpaper_dt_ids[] = {
1147 	{ .compatible = "mayqueen,pixpaper" },
1148 	{}
1149 };
1150 MODULE_DEVICE_TABLE(of, pixpaper_dt_ids);
1151 
1152 static struct spi_driver pixpaper_spi_driver = {
1153 	.driver = {
1154 		.name = "pixpaper",
1155 		.of_match_table = pixpaper_dt_ids,
1156 	},
1157 	.id_table = pixpaper_ids,
1158 	.probe = pixpaper_probe,
1159 	.remove = pixpaper_remove,
1160 };
1161 
1162 module_spi_driver(pixpaper_spi_driver);
1163 
1164 MODULE_AUTHOR("LiangCheng Wang");
1165 MODULE_DESCRIPTION("DRM SPI driver for PIXPAPER e-ink panel");
1166 MODULE_LICENSE("GPL");
1167