1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * FB driver for the ST7789V LCD Controller 4 * 5 * Copyright (C) 2015 Dennis Menschel 6 */ 7 8 #include <linux/bitops.h> 9 #include <linux/delay.h> 10 #include <linux/init.h> 11 #include <linux/kernel.h> 12 #include <linux/module.h> 13 #include <video/mipi_display.h> 14 15 #include "fbtft.h" 16 17 #define DRVNAME "fb_st7789v" 18 19 #define DEFAULT_GAMMA \ 20 "70 2C 2E 15 10 09 48 33 53 0B 19 18 20 25\n" \ 21 "70 2C 2E 15 10 09 48 33 53 0B 19 18 20 25" 22 23 /** 24 * enum st7789v_command - ST7789V display controller commands 25 * 26 * @PORCTRL: porch setting 27 * @GCTRL: gate control 28 * @VCOMS: VCOM setting 29 * @VDVVRHEN: VDV and VRH command enable 30 * @VRHS: VRH set 31 * @VDVS: VDV set 32 * @VCMOFSET: VCOM offset set 33 * @PWCTRL1: power control 1 34 * @PVGAMCTRL: positive voltage gamma control 35 * @NVGAMCTRL: negative voltage gamma control 36 * 37 * The command names are the same as those found in the datasheet to ease 38 * looking up their semantics and usage. 39 * 40 * Note that the ST7789V display controller offers quite a few more commands 41 * which have been omitted from this list as they are not used at the moment. 42 * Furthermore, commands that are compliant with the MIPI DCS have been left 43 * out as well to avoid duplicate entries. 44 */ 45 enum st7789v_command { 46 PORCTRL = 0xB2, 47 GCTRL = 0xB7, 48 VCOMS = 0xBB, 49 VDVVRHEN = 0xC2, 50 VRHS = 0xC3, 51 VDVS = 0xC4, 52 VCMOFSET = 0xC5, 53 PWCTRL1 = 0xD0, 54 PVGAMCTRL = 0xE0, 55 NVGAMCTRL = 0xE1, 56 }; 57 58 #define MADCTL_BGR BIT(3) /* bitmask for RGB/BGR order */ 59 #define MADCTL_MV BIT(5) /* bitmask for page/column order */ 60 #define MADCTL_MX BIT(6) /* bitmask for column address order */ 61 #define MADCTL_MY BIT(7) /* bitmask for page address order */ 62 63 /** 64 * init_display() - initialize the display controller 65 * 66 * @par: FBTFT parameter object 67 * 68 * Most of the commands in this init function set their parameters to the 69 * same default values which are already in place after the display has been 70 * powered up. (The main exception to this rule is the pixel format which 71 * would default to 18 instead of 16 bit per pixel.) 72 * Nonetheless, this sequence can be used as a template for concrete 73 * displays which usually need some adjustments. 74 * 75 * Return: 0 on success, < 0 if error occurred. 76 */ 77 static int init_display(struct fbtft_par *par) 78 { 79 /* turn off sleep mode */ 80 write_reg(par, MIPI_DCS_EXIT_SLEEP_MODE); 81 mdelay(120); 82 83 /* set pixel format to RGB-565 */ 84 write_reg(par, MIPI_DCS_SET_PIXEL_FORMAT, MIPI_DCS_PIXEL_FMT_16BIT); 85 86 write_reg(par, PORCTRL, 0x08, 0x08, 0x00, 0x22, 0x22); 87 88 /* 89 * VGH = 13.26V 90 * VGL = -10.43V 91 */ 92 write_reg(par, GCTRL, 0x35); 93 94 /* 95 * VDV and VRH register values come from command write 96 * (instead of NVM) 97 */ 98 write_reg(par, VDVVRHEN, 0x01, 0xFF); 99 100 /* 101 * VAP = 4.1V + (VCOM + VCOM offset + 0.5 * VDV) 102 * VAN = -4.1V + (VCOM + VCOM offset + 0.5 * VDV) 103 */ 104 write_reg(par, VRHS, 0x0B); 105 106 /* VDV = 0V */ 107 write_reg(par, VDVS, 0x20); 108 109 /* VCOM = 0.9V */ 110 write_reg(par, VCOMS, 0x20); 111 112 /* VCOM offset = 0V */ 113 write_reg(par, VCMOFSET, 0x20); 114 115 /* 116 * AVDD = 6.8V 117 * AVCL = -4.8V 118 * VDS = 2.3V 119 */ 120 write_reg(par, PWCTRL1, 0xA4, 0xA1); 121 122 write_reg(par, MIPI_DCS_SET_DISPLAY_ON); 123 return 0; 124 } 125 126 /** 127 * set_var() - apply LCD properties like rotation and BGR mode 128 * 129 * @par: FBTFT parameter object 130 * 131 * Return: 0 on success, < 0 if error occurred. 132 */ 133 static int set_var(struct fbtft_par *par) 134 { 135 u8 madctl_par = 0; 136 137 if (par->bgr) 138 madctl_par |= MADCTL_BGR; 139 switch (par->info->var.rotate) { 140 case 0: 141 break; 142 case 90: 143 madctl_par |= (MADCTL_MV | MADCTL_MY); 144 break; 145 case 180: 146 madctl_par |= (MADCTL_MX | MADCTL_MY); 147 break; 148 case 270: 149 madctl_par |= (MADCTL_MV | MADCTL_MX); 150 break; 151 default: 152 return -EINVAL; 153 } 154 write_reg(par, MIPI_DCS_SET_ADDRESS_MODE, madctl_par); 155 return 0; 156 } 157 158 /** 159 * set_gamma() - set gamma curves 160 * 161 * @par: FBTFT parameter object 162 * @curves: gamma curves 163 * 164 * Before the gamma curves are applied, they are preprocessed with a bitmask 165 * to ensure syntactically correct input for the display controller. 166 * This implies that the curves input parameter might be changed by this 167 * function and that illegal gamma values are auto-corrected and not 168 * reported as errors. 169 * 170 * Return: 0 on success, < 0 if error occurred. 171 */ 172 static int set_gamma(struct fbtft_par *par, u32 *curves) 173 { 174 int i; 175 int j; 176 int c; /* curve index offset */ 177 178 /* 179 * Bitmasks for gamma curve command parameters. 180 * The masks are the same for both positive and negative voltage 181 * gamma curves. 182 */ 183 static const u8 gamma_par_mask[] = { 184 0xFF, /* V63[3:0], V0[3:0]*/ 185 0x3F, /* V1[5:0] */ 186 0x3F, /* V2[5:0] */ 187 0x1F, /* V4[4:0] */ 188 0x1F, /* V6[4:0] */ 189 0x3F, /* J0[1:0], V13[3:0] */ 190 0x7F, /* V20[6:0] */ 191 0x77, /* V36[2:0], V27[2:0] */ 192 0x7F, /* V43[6:0] */ 193 0x3F, /* J1[1:0], V50[3:0] */ 194 0x1F, /* V57[4:0] */ 195 0x1F, /* V59[4:0] */ 196 0x3F, /* V61[5:0] */ 197 0x3F, /* V62[5:0] */ 198 }; 199 200 for (i = 0; i < par->gamma.num_curves; i++) { 201 c = i * par->gamma.num_values; 202 for (j = 0; j < par->gamma.num_values; j++) 203 curves[c + j] &= gamma_par_mask[j]; 204 write_reg( 205 par, PVGAMCTRL + i, 206 curves[c + 0], curves[c + 1], curves[c + 2], 207 curves[c + 3], curves[c + 4], curves[c + 5], 208 curves[c + 6], curves[c + 7], curves[c + 8], 209 curves[c + 9], curves[c + 10], curves[c + 11], 210 curves[c + 12], curves[c + 13]); 211 } 212 return 0; 213 } 214 215 /** 216 * blank() - blank the display 217 * 218 * @par: FBTFT parameter object 219 * @on: whether to enable or disable blanking the display 220 * 221 * Return: 0 on success, < 0 if error occurred. 222 */ 223 static int blank(struct fbtft_par *par, bool on) 224 { 225 if (on) 226 write_reg(par, MIPI_DCS_SET_DISPLAY_OFF); 227 else 228 write_reg(par, MIPI_DCS_SET_DISPLAY_ON); 229 return 0; 230 } 231 232 static struct fbtft_display display = { 233 .regwidth = 8, 234 .width = 240, 235 .height = 320, 236 .gamma_num = 2, 237 .gamma_len = 14, 238 .gamma = DEFAULT_GAMMA, 239 .fbtftops = { 240 .init_display = init_display, 241 .set_var = set_var, 242 .set_gamma = set_gamma, 243 .blank = blank, 244 }, 245 }; 246 247 FBTFT_REGISTER_DRIVER(DRVNAME, "sitronix,st7789v", &display); 248 249 MODULE_ALIAS("spi:" DRVNAME); 250 MODULE_ALIAS("platform:" DRVNAME); 251 MODULE_ALIAS("spi:st7789v"); 252 MODULE_ALIAS("platform:st7789v"); 253 254 MODULE_DESCRIPTION("FB driver for the ST7789V LCD Controller"); 255 MODULE_AUTHOR("Dennis Menschel"); 256 MODULE_LICENSE("GPL"); 257