1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * FB driver for the UltraChip UC1611 LCD controller
4 *
5 * The display is 4-bit grayscale (16 shades) 240x160.
6 *
7 * Copyright (C) 2015 Henri Chain
8 */
9
10#include <linux/module.h>
11#include <linux/kernel.h>
12#include <linux/init.h>
13#include <linux/gpio/consumer.h>
14#include <linux/spi/spi.h>
15#include <linux/delay.h>
16
17#include "fbtft.h"
18
19#define DRVNAME "fb_uc1611"
20#define WIDTH 240
21#define HEIGHT 160
22#define BPP 8
23#define FPS 40
24
25/*
26 * LCD voltage is a combination of ratio, gain, pot and temp
27 *
28 * V_LCD = V_BIAS * ratio
29 * V_LCD = (C_V0 + C_PM × pot) * (1 + (T - 25) * temp)
30 * C_V0 and C_PM depend on ratio and gain
31 * T is ambient temperature
32 */
33
34/* BR -> actual ratio: 0-3 -> 5, 10, 11, 13 */
35static unsigned int ratio = 2;
36module_param(ratio, uint, 0000);
37MODULE_PARM_DESC(ratio, "BR[1:0] Bias voltage ratio: 0-3 (default: 2)");
38
39static unsigned int gain = 3;
40module_param(gain, uint, 0000);
41MODULE_PARM_DESC(gain, "GN[1:0] Bias voltage gain: 0-3 (default: 3)");
42
43static unsigned int pot = 16;
44module_param(pot, uint, 0000);
45MODULE_PARM_DESC(pot, "PM[6:0] Bias voltage pot.: 0-63 (default: 16)");
46
47/* TC -> % compensation per deg C: 0-3 -> -.05, -.10, -.015, -.20 */
48static unsigned int temp;
49module_param(temp, uint, 0000);
50MODULE_PARM_DESC(temp, "TC[1:0] Temperature compensation: 0-3 (default: 0)");
51
52/* PC[1:0] -> LCD capacitance: 0-3 -> <20nF, 20-28 nF, 29-40 nF, 40-56 nF */
53static unsigned int load = 1;
54module_param(load, uint, 0000);
55MODULE_PARM_DESC(load, "PC[1:0] Panel Loading: 0-3 (default: 1)");
56
57/* PC[3:2] -> V_LCD: 0, 1, 3 -> ext., int. with ratio = 5, int. standard */
58static unsigned int pump = 3;
59module_param(pump, uint, 0000);
60MODULE_PARM_DESC(pump, "PC[3:2] Pump control: 0,1,3 (default: 3)");
61
62static int init_display(struct fbtft_par *par)
63{
64 int ret;
65
66 /*
67 * Set CS active inverse polarity: just setting SPI_CS_HIGH does not
68 * work with GPIO based chip selects that are logically active high
69 * but inverted inside the GPIO library, so enforce inverted
70 * semantics.
71 */
72 par->spi->mode ^= SPI_CS_HIGH;
73 ret = spi_setup(spi: par->spi);
74 if (ret) {
75 dev_err(par->info->device,
76 "Could not set inverse CS polarity\n");
77 return ret;
78 }
79
80 /* Reset controller */
81 write_reg(par, 0xE2);
82
83 /* Set bias ratio */
84 write_reg(par, 0xE8 | (ratio & 0x03));
85
86 /* Set bias gain and potentiometer */
87 write_reg(par, 0x81);
88 write_reg(par, (gain & 0x03) << 6 | (pot & 0x3F));
89
90 /* Set temperature compensation */
91 write_reg(par, 0x24 | (temp & 0x03));
92
93 /* Set panel loading */
94 write_reg(par, 0x28 | (load & 0x03));
95
96 /* Set pump control */
97 write_reg(par, 0x2C | (pump & 0x03));
98
99 /* Set inverse display */
100 write_reg(par, 0xA6 | 0x01);
101
102 /* Set 4-bit grayscale mode */
103 write_reg(par, 0xD0 | (0x02 & 0x03));
104
105 /* Set Display enable */
106 write_reg(par, 0xA8 | 0x07);
107
108 return 0;
109}
110
111static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
112{
113 switch (par->info->var.rotate) {
114 case 90:
115 case 270:
116 /* Set column address */
117 write_reg(par, ys & 0x0F);
118 write_reg(par, 0x10 | (ys >> 4));
119
120 /* Set page address (divide xs by 2) (not used by driver) */
121 write_reg(par, 0x60 | ((xs >> 1) & 0x0F));
122 write_reg(par, 0x70 | (xs >> 5));
123 break;
124 default:
125 /* Set column address (not used by driver) */
126 write_reg(par, xs & 0x0F);
127 write_reg(par, 0x10 | (xs >> 4));
128
129 /* Set page address (divide ys by 2) */
130 write_reg(par, 0x60 | ((ys >> 1) & 0x0F));
131 write_reg(par, 0x70 | (ys >> 5));
132 break;
133 }
134}
135
136static int blank(struct fbtft_par *par, bool on)
137{
138 fbtft_par_dbg(DEBUG_BLANK, par, "(%s=%s)\n",
139 __func__, on ? "true" : "false");
140
141 if (on)
142 write_reg(par, 0xA8 | 0x00);
143 else
144 write_reg(par, 0xA8 | 0x07);
145 return 0;
146}
147
148static int set_var(struct fbtft_par *par)
149{
150 /* par->info->fix.visual = FB_VISUAL_PSEUDOCOLOR; */
151 par->info->var.grayscale = 1;
152 par->info->var.red.offset = 0;
153 par->info->var.red.length = 8;
154 par->info->var.green.offset = 0;
155 par->info->var.green.length = 8;
156 par->info->var.blue.offset = 0;
157 par->info->var.blue.length = 8;
158 par->info->var.transp.offset = 0;
159 par->info->var.transp.length = 0;
160
161 switch (par->info->var.rotate) {
162 case 90:
163 /* Set RAM address control */
164 write_reg(par, 0x88
165 | (0x0 & 0x1) << 2 /* Increment positively */
166 | (0x1 << 1) /* Increment page first */
167 | 0x1); /* Wrap around (default) */
168
169 /* Set LCD mapping */
170 write_reg(par, 0xC0
171 | (0x0 & 0x1) << 2 /* Mirror Y OFF */
172 | (0x0 & 0x1) << 1 /* Mirror X OFF */
173 | (0x0 & 0x1)); /* MS nibble last (default) */
174 break;
175 case 180:
176 /* Set RAM address control */
177 write_reg(par, 0x88
178 | (0x0 & 0x1) << 2 /* Increment positively */
179 | (0x0 & 0x1) << 1 /* Increment column first */
180 | 0x1); /* Wrap around (default) */
181
182 /* Set LCD mapping */
183 write_reg(par, 0xC0
184 | (0x1 << 2) /* Mirror Y ON */
185 | (0x0 & 0x1) << 1 /* Mirror X OFF */
186 | (0x0 & 0x1)); /* MS nibble last (default) */
187 break;
188 case 270:
189 /* Set RAM address control */
190 write_reg(par, 0x88
191 | (0x0 & 0x1) << 2 /* Increment positively */
192 | (0x1 << 1) /* Increment page first */
193 | 0x1); /* Wrap around (default) */
194
195 /* Set LCD mapping */
196 write_reg(par, 0xC0
197 | (0x1 << 2) /* Mirror Y ON */
198 | (0x1 << 1) /* Mirror X ON */
199 | (0x0 & 0x1)); /* MS nibble last (default) */
200 break;
201 default:
202 /* Set RAM address control */
203 write_reg(par, 0x88
204 | (0x0 & 0x1) << 2 /* Increment positively */
205 | (0x0 & 0x1) << 1 /* Increment column first */
206 | 0x1); /* Wrap around (default) */
207
208 /* Set LCD mapping */
209 write_reg(par, 0xC0
210 | (0x0 & 0x1) << 2 /* Mirror Y OFF */
211 | (0x1 << 1) /* Mirror X ON */
212 | (0x0 & 0x1)); /* MS nibble last (default) */
213 break;
214 }
215
216 return 0;
217}
218
219static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
220{
221 u8 *vmem8 = (u8 *)(par->info->screen_buffer);
222 u8 *buf8 = par->txbuf.buf;
223 u16 *buf16 = par->txbuf.buf;
224 int line_length = par->info->fix.line_length;
225 int y_start = offset / line_length;
226 int y_end = (offset + len - 1) / line_length;
227 int x, y, i;
228 int ret = 0;
229
230 switch (par->pdata->display.buswidth) {
231 case 8:
232 switch (par->info->var.rotate) {
233 case 90:
234 case 270:
235 i = y_start * line_length;
236 for (y = y_start; y <= y_end; y++) {
237 for (x = 0; x < line_length; x += 2) {
238 *buf8 = vmem8[i] >> 4;
239 *buf8 |= vmem8[i + 1] & 0xF0;
240 buf8++;
241 i += 2;
242 }
243 }
244 break;
245 default:
246 /* Must be even because pages are two lines */
247 y_start &= 0xFE;
248 i = y_start * line_length;
249 for (y = y_start; y <= y_end; y += 2) {
250 for (x = 0; x < line_length; x++) {
251 *buf8 = vmem8[i] >> 4;
252 *buf8 |= vmem8[i + line_length] & 0xF0;
253 buf8++;
254 i++;
255 }
256 i += line_length;
257 }
258 break;
259 }
260 gpiod_set_value(desc: par->gpio.dc, value: 1);
261
262 /* Write data */
263 ret = par->fbtftops.write(par, par->txbuf.buf, len / 2);
264 break;
265 case 9:
266 switch (par->info->var.rotate) {
267 case 90:
268 case 270:
269 i = y_start * line_length;
270 for (y = y_start; y <= y_end; y++) {
271 for (x = 0; x < line_length; x += 2) {
272 *buf16 = 0x100;
273 *buf16 |= vmem8[i] >> 4;
274 *buf16 |= vmem8[i + 1] & 0xF0;
275 buf16++;
276 i += 2;
277 }
278 }
279 break;
280 default:
281 /* Must be even because pages are two lines */
282 y_start &= 0xFE;
283 i = y_start * line_length;
284 for (y = y_start; y <= y_end; y += 2) {
285 for (x = 0; x < line_length; x++) {
286 *buf16 = 0x100;
287 *buf16 |= vmem8[i] >> 4;
288 *buf16 |= vmem8[i + line_length] & 0xF0;
289 buf16++;
290 i++;
291 }
292 i += line_length;
293 }
294 break;
295 }
296
297 /* Write data */
298 ret = par->fbtftops.write(par, par->txbuf.buf, len);
299 break;
300 default:
301 dev_err(par->info->device, "unsupported buswidth %d\n",
302 par->pdata->display.buswidth);
303 }
304
305 if (ret < 0)
306 dev_err(par->info->device, "write failed and returned: %d\n",
307 ret);
308
309 return ret;
310}
311
312static struct fbtft_display display = {
313 .txbuflen = -1,
314 .regwidth = 8,
315 .width = WIDTH,
316 .height = HEIGHT,
317 .bpp = BPP,
318 .fps = FPS,
319 .fbtftops = {
320 .write_vmem = write_vmem,
321 .init_display = init_display,
322 .set_addr_win = set_addr_win,
323 .set_var = set_var,
324 .blank = blank,
325 },
326};
327
328FBTFT_REGISTER_DRIVER(DRVNAME, "ultrachip,uc1611", &display);
329
330MODULE_ALIAS("spi:" DRVNAME);
331MODULE_ALIAS("platform:" DRVNAME);
332MODULE_ALIAS("spi:uc1611");
333MODULE_ALIAS("platform:uc1611");
334
335MODULE_DESCRIPTION("FB driver for the UC1611 LCD controller");
336MODULE_AUTHOR("Henri Chain");
337MODULE_LICENSE("GPL");
338

source code of linux/drivers/staging/fbtft/fb_uc1611.c