1 /*
2 * FB driver for the ST7789V LCD Controller
3 *
4 * Copyright (C) 2015 Dennis Menschel
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 */
16
17 #include <linux/bitops.h>
18 #include <linux/delay.h>
19 #include <linux/init.h>
20 #include <linux/kernel.h>
21 #include <linux/module.h>
22 #include <video/mipi_display.h>
23
24 #include "fbtft.h"
25
26 #define DRVNAME "fb_st7789v"
27
28 #define DEFAULT_GAMMA \
29 "70 2C 2E 15 10 09 48 33 53 0B 19 18 20 25\n" \
30 "70 2C 2E 15 10 09 48 33 53 0B 19 18 20 25"
31
32 /**
33 * enum st7789v_command - ST7789V display controller commands
34 *
35 * @PORCTRL: porch setting
36 * @GCTRL: gate control
37 * @VCOMS: VCOM setting
38 * @VDVVRHEN: VDV and VRH command enable
39 * @VRHS: VRH set
40 * @VDVS: VDV set
41 * @VCMOFSET: VCOM offset set
42 * @PWCTRL1: power control 1
43 * @PVGAMCTRL: positive voltage gamma control
44 * @NVGAMCTRL: negative voltage gamma control
45 *
46 * The command names are the same as those found in the datasheet to ease
47 * looking up their semantics and usage.
48 *
49 * Note that the ST7789V display controller offers quite a few more commands
50 * which have been omitted from this list as they are not used at the moment.
51 * Furthermore, commands that are compliant with the MIPI DCS have been left
52 * out as well to avoid duplicate entries.
53 */
54 enum st7789v_command {
55 PORCTRL = 0xB2,
56 GCTRL = 0xB7,
57 VCOMS = 0xBB,
58 VDVVRHEN = 0xC2,
59 VRHS = 0xC3,
60 VDVS = 0xC4,
61 VCMOFSET = 0xC5,
62 PWCTRL1 = 0xD0,
63 PVGAMCTRL = 0xE0,
64 NVGAMCTRL = 0xE1,
65 };
66
67 #define MADCTL_BGR BIT(3) /* bitmask for RGB/BGR order */
68 #define MADCTL_MV BIT(5) /* bitmask for page/column order */
69 #define MADCTL_MX BIT(6) /* bitmask for column address order */
70 #define MADCTL_MY BIT(7) /* bitmask for page address order */
71
72 /**
73 * init_display() - initialize the display controller
74 *
75 * @par: FBTFT parameter object
76 *
77 * Most of the commands in this init function set their parameters to the
78 * same default values which are already in place after the display has been
79 * powered up. (The main exception to this rule is the pixel format which
80 * would default to 18 instead of 16 bit per pixel.)
81 * Nonetheless, this sequence can be used as a template for concrete
82 * displays which usually need some adjustments.
83 *
84 * Return: 0 on success, < 0 if error occurred.
85 */
init_display(struct fbtft_par * par)86 static int init_display(struct fbtft_par *par)
87 {
88 /* turn off sleep mode */
89 write_reg(par, MIPI_DCS_EXIT_SLEEP_MODE);
90 mdelay(120);
91
92 /* set pixel format to RGB-565 */
93 write_reg(par, MIPI_DCS_SET_PIXEL_FORMAT, MIPI_DCS_PIXEL_FMT_16BIT);
94
95 write_reg(par, PORCTRL, 0x08, 0x08, 0x00, 0x22, 0x22);
96
97 /*
98 * VGH = 13.26V
99 * VGL = -10.43V
100 */
101 write_reg(par, GCTRL, 0x35);
102
103 /*
104 * VDV and VRH register values come from command write
105 * (instead of NVM)
106 */
107 write_reg(par, VDVVRHEN, 0x01, 0xFF);
108
109 /*
110 * VAP = 4.1V + (VCOM + VCOM offset + 0.5 * VDV)
111 * VAN = -4.1V + (VCOM + VCOM offset + 0.5 * VDV)
112 */
113 write_reg(par, VRHS, 0x0B);
114
115 /* VDV = 0V */
116 write_reg(par, VDVS, 0x20);
117
118 /* VCOM = 0.9V */
119 write_reg(par, VCOMS, 0x20);
120
121 /* VCOM offset = 0V */
122 write_reg(par, VCMOFSET, 0x20);
123
124 /*
125 * AVDD = 6.8V
126 * AVCL = -4.8V
127 * VDS = 2.3V
128 */
129 write_reg(par, PWCTRL1, 0xA4, 0xA1);
130
131 write_reg(par, MIPI_DCS_SET_DISPLAY_ON);
132 return 0;
133 }
134
135 /**
136 * set_var() - apply LCD properties like rotation and BGR mode
137 *
138 * @par: FBTFT parameter object
139 *
140 * Return: 0 on success, < 0 if error occurred.
141 */
set_var(struct fbtft_par * par)142 static int set_var(struct fbtft_par *par)
143 {
144 u8 madctl_par = 0;
145
146 if (par->bgr)
147 madctl_par |= MADCTL_BGR;
148 switch (par->info->var.rotate) {
149 case 0:
150 break;
151 case 90:
152 madctl_par |= (MADCTL_MV | MADCTL_MY);
153 break;
154 case 180:
155 madctl_par |= (MADCTL_MX | MADCTL_MY);
156 break;
157 case 270:
158 madctl_par |= (MADCTL_MV | MADCTL_MX);
159 break;
160 default:
161 return -EINVAL;
162 }
163 write_reg(par, MIPI_DCS_SET_ADDRESS_MODE, madctl_par);
164 return 0;
165 }
166
167 /**
168 * set_gamma() - set gamma curves
169 *
170 * @par: FBTFT parameter object
171 * @curves: gamma curves
172 *
173 * Before the gamma curves are applied, they are preprocessed with a bitmask
174 * to ensure syntactically correct input for the display controller.
175 * This implies that the curves input parameter might be changed by this
176 * function and that illegal gamma values are auto-corrected and not
177 * reported as errors.
178 *
179 * Return: 0 on success, < 0 if error occurred.
180 */
set_gamma(struct fbtft_par * par,unsigned long * curves)181 static int set_gamma(struct fbtft_par *par, unsigned long *curves)
182 {
183 int i;
184 int j;
185 int c; /* curve index offset */
186
187 /*
188 * Bitmasks for gamma curve command parameters.
189 * The masks are the same for both positive and negative voltage
190 * gamma curves.
191 */
192 const u8 gamma_par_mask[] = {
193 0xFF, /* V63[3:0], V0[3:0]*/
194 0x3F, /* V1[5:0] */
195 0x3F, /* V2[5:0] */
196 0x1F, /* V4[4:0] */
197 0x1F, /* V6[4:0] */
198 0x3F, /* J0[1:0], V13[3:0] */
199 0x7F, /* V20[6:0] */
200 0x77, /* V36[2:0], V27[2:0] */
201 0x7F, /* V43[6:0] */
202 0x3F, /* J1[1:0], V50[3:0] */
203 0x1F, /* V57[4:0] */
204 0x1F, /* V59[4:0] */
205 0x3F, /* V61[5:0] */
206 0x3F, /* V62[5:0] */
207 };
208
209 for (i = 0; i < par->gamma.num_curves; i++) {
210 c = i * par->gamma.num_values;
211 for (j = 0; j < par->gamma.num_values; j++)
212 curves[c + j] &= gamma_par_mask[j];
213 write_reg(
214 par, PVGAMCTRL + i,
215 curves[c + 0], curves[c + 1], curves[c + 2],
216 curves[c + 3], curves[c + 4], curves[c + 5],
217 curves[c + 6], curves[c + 7], curves[c + 8],
218 curves[c + 9], curves[c + 10], curves[c + 11],
219 curves[c + 12], curves[c + 13]);
220 }
221 return 0;
222 }
223
224 /**
225 * blank() - blank the display
226 *
227 * @par: FBTFT parameter object
228 * @on: whether to enable or disable blanking the display
229 *
230 * Return: 0 on success, < 0 if error occurred.
231 */
blank(struct fbtft_par * par,bool on)232 static int blank(struct fbtft_par *par, bool on)
233 {
234 if (on)
235 write_reg(par, MIPI_DCS_SET_DISPLAY_OFF);
236 else
237 write_reg(par, MIPI_DCS_SET_DISPLAY_ON);
238 return 0;
239 }
240
241 static struct fbtft_display display = {
242 .regwidth = 8,
243 .width = 240,
244 .height = 320,
245 .gamma_num = 2,
246 .gamma_len = 14,
247 .gamma = DEFAULT_GAMMA,
248 .fbtftops = {
249 .init_display = init_display,
250 .set_var = set_var,
251 .set_gamma = set_gamma,
252 .blank = blank,
253 },
254 };
255
256 FBTFT_REGISTER_DRIVER(DRVNAME, "sitronix,st7789v", &display);
257
258 MODULE_ALIAS("spi:" DRVNAME);
259 MODULE_ALIAS("platform:" DRVNAME);
260 MODULE_ALIAS("spi:st7789v");
261 MODULE_ALIAS("platform:st7789v");
262
263 MODULE_DESCRIPTION("FB driver for the ST7789V LCD Controller");
264 MODULE_AUTHOR("Dennis Menschel");
265 MODULE_LICENSE("GPL");
266