1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * (C) Copyright 2008
4 * Stefano Babic, DENX Software Engineering, sbabic@denx.de.
5 *
6 * This driver implements a lcd device for the ILITEK 922x display
7 * controller. The interface to the display is SPI and the display's
8 * memory is cyclically updated over the RGB interface.
9 */
10
11#include <linux/fb.h>
12#include <linux/delay.h>
13#include <linux/errno.h>
14#include <linux/init.h>
15#include <linux/kernel.h>
16#include <linux/lcd.h>
17#include <linux/module.h>
18#include <linux/of.h>
19#include <linux/slab.h>
20#include <linux/spi/spi.h>
21#include <linux/string.h>
22
23/* Register offset, see manual section 8.2 */
24#define REG_START_OSCILLATION 0x00
25#define REG_DRIVER_CODE_READ 0x00
26#define REG_DRIVER_OUTPUT_CONTROL 0x01
27#define REG_LCD_AC_DRIVEING_CONTROL 0x02
28#define REG_ENTRY_MODE 0x03
29#define REG_COMPARE_1 0x04
30#define REG_COMPARE_2 0x05
31#define REG_DISPLAY_CONTROL_1 0x07
32#define REG_DISPLAY_CONTROL_2 0x08
33#define REG_DISPLAY_CONTROL_3 0x09
34#define REG_FRAME_CYCLE_CONTROL 0x0B
35#define REG_EXT_INTF_CONTROL 0x0C
36#define REG_POWER_CONTROL_1 0x10
37#define REG_POWER_CONTROL_2 0x11
38#define REG_POWER_CONTROL_3 0x12
39#define REG_POWER_CONTROL_4 0x13
40#define REG_RAM_ADDRESS_SET 0x21
41#define REG_WRITE_DATA_TO_GRAM 0x22
42#define REG_RAM_WRITE_MASK1 0x23
43#define REG_RAM_WRITE_MASK2 0x24
44#define REG_GAMMA_CONTROL_1 0x30
45#define REG_GAMMA_CONTROL_2 0x31
46#define REG_GAMMA_CONTROL_3 0x32
47#define REG_GAMMA_CONTROL_4 0x33
48#define REG_GAMMA_CONTROL_5 0x34
49#define REG_GAMMA_CONTROL_6 0x35
50#define REG_GAMMA_CONTROL_7 0x36
51#define REG_GAMMA_CONTROL_8 0x37
52#define REG_GAMMA_CONTROL_9 0x38
53#define REG_GAMMA_CONTROL_10 0x39
54#define REG_GATE_SCAN_CONTROL 0x40
55#define REG_VERT_SCROLL_CONTROL 0x41
56#define REG_FIRST_SCREEN_DRIVE_POS 0x42
57#define REG_SECOND_SCREEN_DRIVE_POS 0x43
58#define REG_RAM_ADDR_POS_H 0x44
59#define REG_RAM_ADDR_POS_V 0x45
60#define REG_OSCILLATOR_CONTROL 0x4F
61#define REG_GPIO 0x60
62#define REG_OTP_VCM_PROGRAMMING 0x61
63#define REG_OTP_VCM_STATUS_ENABLE 0x62
64#define REG_OTP_PROGRAMMING_ID_KEY 0x65
65
66/*
67 * maximum frequency for register access
68 * (not for the GRAM access)
69 */
70#define ILITEK_MAX_FREQ_REG 4000000
71
72/*
73 * Device ID as found in the datasheet (supports 9221 and 9222)
74 */
75#define ILITEK_DEVICE_ID 0x9220
76#define ILITEK_DEVICE_ID_MASK 0xFFF0
77
78/* Last two bits in the START BYTE */
79#define START_RS_INDEX 0
80#define START_RS_REG 1
81#define START_RW_WRITE 0
82#define START_RW_READ 1
83
84/*
85 * START_BYTE(id, rs, rw)
86 *
87 * Set the start byte according to the required operation.
88 * The start byte is defined as:
89 * ----------------------------------
90 * | 0 | 1 | 1 | 1 | 0 | ID | RS | RW |
91 * ----------------------------------
92 * @id: display's id as set by the manufacturer
93 * @rs: operation type bit, one of:
94 * - START_RS_INDEX set the index register
95 * - START_RS_REG write/read registers/GRAM
96 * @rw: read/write operation
97 * - START_RW_WRITE write
98 * - START_RW_READ read
99 */
100#define START_BYTE(id, rs, rw) \
101 (0x70 | (((id) & 0x01) << 2) | (((rs) & 0x01) << 1) | ((rw) & 0x01))
102
103/*
104 * CHECK_FREQ_REG(spi_device s, spi_transfer x) - Check the frequency
105 * for the SPI transfer. According to the datasheet, the controller
106 * accept higher frequency for the GRAM transfer, but it requires
107 * lower frequency when the registers are read/written.
108 * The macro sets the frequency in the spi_transfer structure if
109 * the frequency exceeds the maximum value.
110 * @s: pointer to an SPI device
111 * @x: pointer to the read/write buffer pair
112 */
113#define CHECK_FREQ_REG(s, x) \
114 do { \
115 if (s->max_speed_hz > ILITEK_MAX_FREQ_REG) \
116 ((struct spi_transfer *)x)->speed_hz = \
117 ILITEK_MAX_FREQ_REG; \
118 } while (0)
119
120#define CMD_BUFSIZE 16
121
122#define POWER_IS_ON(pwr) ((pwr) <= FB_BLANK_NORMAL)
123
124#define set_tx_byte(b) (tx_invert ? ~(b) : b)
125
126/*
127 * ili922x_id - id as set by manufacturer
128 */
129static int ili922x_id = 1;
130module_param(ili922x_id, int, 0);
131
132static int tx_invert;
133module_param(tx_invert, int, 0);
134
135/*
136 * driver's private structure
137 */
138struct ili922x {
139 struct spi_device *spi;
140 struct lcd_device *ld;
141 int power;
142};
143
144/**
145 * ili922x_read_status - read status register from display
146 * @spi: spi device
147 * @rs: output value
148 */
149static int ili922x_read_status(struct spi_device *spi, u16 *rs)
150{
151 struct spi_message msg;
152 struct spi_transfer xfer;
153 unsigned char tbuf[CMD_BUFSIZE];
154 unsigned char rbuf[CMD_BUFSIZE];
155 int ret, i;
156
157 memset(&xfer, 0, sizeof(struct spi_transfer));
158 spi_message_init(m: &msg);
159 xfer.tx_buf = tbuf;
160 xfer.rx_buf = rbuf;
161 xfer.cs_change = 1;
162 CHECK_FREQ_REG(spi, &xfer);
163
164 tbuf[0] = set_tx_byte(START_BYTE(ili922x_id, START_RS_INDEX,
165 START_RW_READ));
166 /*
167 * we need 4-byte xfer here due to invalid dummy byte
168 * received after start byte
169 */
170 for (i = 1; i < 4; i++)
171 tbuf[i] = set_tx_byte(0); /* dummy */
172
173 xfer.bits_per_word = 8;
174 xfer.len = 4;
175 spi_message_add_tail(t: &xfer, m: &msg);
176 ret = spi_sync(spi, message: &msg);
177 if (ret < 0) {
178 dev_dbg(&spi->dev, "Error sending SPI message 0x%x", ret);
179 return ret;
180 }
181
182 *rs = (rbuf[2] << 8) + rbuf[3];
183 return 0;
184}
185
186/**
187 * ili922x_read - read register from display
188 * @spi: spi device
189 * @reg: offset of the register to be read
190 * @rx: output value
191 */
192static int ili922x_read(struct spi_device *spi, u8 reg, u16 *rx)
193{
194 struct spi_message msg;
195 struct spi_transfer xfer_regindex, xfer_regvalue;
196 unsigned char tbuf[CMD_BUFSIZE];
197 unsigned char rbuf[CMD_BUFSIZE];
198 int ret, len = 0, send_bytes;
199
200 memset(&xfer_regindex, 0, sizeof(struct spi_transfer));
201 memset(&xfer_regvalue, 0, sizeof(struct spi_transfer));
202 spi_message_init(m: &msg);
203 xfer_regindex.tx_buf = tbuf;
204 xfer_regindex.rx_buf = rbuf;
205 xfer_regindex.cs_change = 1;
206 CHECK_FREQ_REG(spi, &xfer_regindex);
207
208 tbuf[0] = set_tx_byte(START_BYTE(ili922x_id, START_RS_INDEX,
209 START_RW_WRITE));
210 tbuf[1] = set_tx_byte(0);
211 tbuf[2] = set_tx_byte(reg);
212 xfer_regindex.bits_per_word = 8;
213 len = xfer_regindex.len = 3;
214 spi_message_add_tail(t: &xfer_regindex, m: &msg);
215
216 send_bytes = len;
217
218 tbuf[len++] = set_tx_byte(START_BYTE(ili922x_id, START_RS_REG,
219 START_RW_READ));
220 tbuf[len++] = set_tx_byte(0);
221 tbuf[len] = set_tx_byte(0);
222
223 xfer_regvalue.cs_change = 1;
224 xfer_regvalue.len = 3;
225 xfer_regvalue.tx_buf = &tbuf[send_bytes];
226 xfer_regvalue.rx_buf = &rbuf[send_bytes];
227 CHECK_FREQ_REG(spi, &xfer_regvalue);
228
229 spi_message_add_tail(t: &xfer_regvalue, m: &msg);
230 ret = spi_sync(spi, message: &msg);
231 if (ret < 0) {
232 dev_dbg(&spi->dev, "Error sending SPI message 0x%x", ret);
233 return ret;
234 }
235
236 *rx = (rbuf[1 + send_bytes] << 8) + rbuf[2 + send_bytes];
237 return 0;
238}
239
240/**
241 * ili922x_write - write a controller register
242 * @spi: struct spi_device *
243 * @reg: offset of the register to be written
244 * @value: value to be written
245 */
246static int ili922x_write(struct spi_device *spi, u8 reg, u16 value)
247{
248 struct spi_message msg;
249 struct spi_transfer xfer_regindex, xfer_regvalue;
250 unsigned char tbuf[CMD_BUFSIZE];
251 unsigned char rbuf[CMD_BUFSIZE];
252 int ret;
253
254 memset(&xfer_regindex, 0, sizeof(struct spi_transfer));
255 memset(&xfer_regvalue, 0, sizeof(struct spi_transfer));
256
257 spi_message_init(m: &msg);
258 xfer_regindex.tx_buf = tbuf;
259 xfer_regindex.rx_buf = rbuf;
260 xfer_regindex.cs_change = 1;
261 CHECK_FREQ_REG(spi, &xfer_regindex);
262
263 tbuf[0] = set_tx_byte(START_BYTE(ili922x_id, START_RS_INDEX,
264 START_RW_WRITE));
265 tbuf[1] = set_tx_byte(0);
266 tbuf[2] = set_tx_byte(reg);
267 xfer_regindex.bits_per_word = 8;
268 xfer_regindex.len = 3;
269 spi_message_add_tail(t: &xfer_regindex, m: &msg);
270
271 ret = spi_sync(spi, message: &msg);
272 if (ret < 0) {
273 dev_err(&spi->dev, "Error sending SPI message 0x%x", ret);
274 return ret;
275 }
276
277 spi_message_init(m: &msg);
278 tbuf[0] = set_tx_byte(START_BYTE(ili922x_id, START_RS_REG,
279 START_RW_WRITE));
280 tbuf[1] = set_tx_byte((value & 0xFF00) >> 8);
281 tbuf[2] = set_tx_byte(value & 0x00FF);
282
283 xfer_regvalue.cs_change = 1;
284 xfer_regvalue.len = 3;
285 xfer_regvalue.tx_buf = tbuf;
286 xfer_regvalue.rx_buf = rbuf;
287 CHECK_FREQ_REG(spi, &xfer_regvalue);
288
289 spi_message_add_tail(t: &xfer_regvalue, m: &msg);
290
291 ret = spi_sync(spi, message: &msg);
292 if (ret < 0) {
293 dev_err(&spi->dev, "Error sending SPI message 0x%x", ret);
294 return ret;
295 }
296 return 0;
297}
298
299#ifdef DEBUG
300/**
301 * ili922x_reg_dump - dump all registers
302 *
303 * @spi: pointer to an SPI device
304 */
305static void ili922x_reg_dump(struct spi_device *spi)
306{
307 u8 reg;
308 u16 rx;
309
310 dev_dbg(&spi->dev, "ILI922x configuration registers:\n");
311 for (reg = REG_START_OSCILLATION;
312 reg <= REG_OTP_PROGRAMMING_ID_KEY; reg++) {
313 ili922x_read(spi, reg, &rx);
314 dev_dbg(&spi->dev, "reg @ 0x%02X: 0x%04X\n", reg, rx);
315 }
316}
317#else
318static inline void ili922x_reg_dump(struct spi_device *spi) {}
319#endif
320
321/**
322 * set_write_to_gram_reg - initialize the display to write the GRAM
323 * @spi: spi device
324 */
325static void set_write_to_gram_reg(struct spi_device *spi)
326{
327 struct spi_message msg;
328 struct spi_transfer xfer;
329 unsigned char tbuf[CMD_BUFSIZE];
330
331 memset(&xfer, 0, sizeof(struct spi_transfer));
332
333 spi_message_init(m: &msg);
334 xfer.tx_buf = tbuf;
335 xfer.rx_buf = NULL;
336 xfer.cs_change = 1;
337
338 tbuf[0] = START_BYTE(ili922x_id, START_RS_INDEX, START_RW_WRITE);
339 tbuf[1] = 0;
340 tbuf[2] = REG_WRITE_DATA_TO_GRAM;
341
342 xfer.bits_per_word = 8;
343 xfer.len = 3;
344 spi_message_add_tail(t: &xfer, m: &msg);
345 spi_sync(spi, message: &msg);
346}
347
348/**
349 * ili922x_poweron - turn the display on
350 * @spi: spi device
351 *
352 * The sequence to turn on the display is taken from
353 * the datasheet and/or the example code provided by the
354 * manufacturer.
355 */
356static int ili922x_poweron(struct spi_device *spi)
357{
358 int ret;
359
360 /* Power on */
361 ret = ili922x_write(spi, REG_POWER_CONTROL_1, value: 0x0000);
362 usleep_range(min: 10000, max: 10500);
363 ret += ili922x_write(spi, REG_POWER_CONTROL_2, value: 0x0000);
364 ret += ili922x_write(spi, REG_POWER_CONTROL_3, value: 0x0000);
365 msleep(msecs: 40);
366 ret += ili922x_write(spi, REG_POWER_CONTROL_4, value: 0x0000);
367 msleep(msecs: 40);
368 /* register 0x56 is not documented in the datasheet */
369 ret += ili922x_write(spi, reg: 0x56, value: 0x080F);
370 ret += ili922x_write(spi, REG_POWER_CONTROL_1, value: 0x4240);
371 usleep_range(min: 10000, max: 10500);
372 ret += ili922x_write(spi, REG_POWER_CONTROL_2, value: 0x0000);
373 ret += ili922x_write(spi, REG_POWER_CONTROL_3, value: 0x0014);
374 msleep(msecs: 40);
375 ret += ili922x_write(spi, REG_POWER_CONTROL_4, value: 0x1319);
376 msleep(msecs: 40);
377
378 return ret;
379}
380
381/**
382 * ili922x_poweroff - turn the display off
383 * @spi: spi device
384 */
385static int ili922x_poweroff(struct spi_device *spi)
386{
387 int ret;
388
389 /* Power off */
390 ret = ili922x_write(spi, REG_POWER_CONTROL_1, value: 0x0000);
391 usleep_range(min: 10000, max: 10500);
392 ret += ili922x_write(spi, REG_POWER_CONTROL_2, value: 0x0000);
393 ret += ili922x_write(spi, REG_POWER_CONTROL_3, value: 0x0000);
394 msleep(msecs: 40);
395 ret += ili922x_write(spi, REG_POWER_CONTROL_4, value: 0x0000);
396 msleep(msecs: 40);
397
398 return ret;
399}
400
401/**
402 * ili922x_display_init - initialize the display by setting
403 * the configuration registers
404 * @spi: spi device
405 */
406static void ili922x_display_init(struct spi_device *spi)
407{
408 ili922x_write(spi, REG_START_OSCILLATION, value: 1);
409 usleep_range(min: 10000, max: 10500);
410 ili922x_write(spi, REG_DRIVER_OUTPUT_CONTROL, value: 0x691B);
411 ili922x_write(spi, REG_LCD_AC_DRIVEING_CONTROL, value: 0x0700);
412 ili922x_write(spi, REG_ENTRY_MODE, value: 0x1030);
413 ili922x_write(spi, REG_COMPARE_1, value: 0x0000);
414 ili922x_write(spi, REG_COMPARE_2, value: 0x0000);
415 ili922x_write(spi, REG_DISPLAY_CONTROL_1, value: 0x0037);
416 ili922x_write(spi, REG_DISPLAY_CONTROL_2, value: 0x0202);
417 ili922x_write(spi, REG_DISPLAY_CONTROL_3, value: 0x0000);
418 ili922x_write(spi, REG_FRAME_CYCLE_CONTROL, value: 0x0000);
419
420 /* Set RGB interface */
421 ili922x_write(spi, REG_EXT_INTF_CONTROL, value: 0x0110);
422
423 ili922x_poweron(spi);
424
425 ili922x_write(spi, REG_GAMMA_CONTROL_1, value: 0x0302);
426 ili922x_write(spi, REG_GAMMA_CONTROL_2, value: 0x0407);
427 ili922x_write(spi, REG_GAMMA_CONTROL_3, value: 0x0304);
428 ili922x_write(spi, REG_GAMMA_CONTROL_4, value: 0x0203);
429 ili922x_write(spi, REG_GAMMA_CONTROL_5, value: 0x0706);
430 ili922x_write(spi, REG_GAMMA_CONTROL_6, value: 0x0407);
431 ili922x_write(spi, REG_GAMMA_CONTROL_7, value: 0x0706);
432 ili922x_write(spi, REG_GAMMA_CONTROL_8, value: 0x0000);
433 ili922x_write(spi, REG_GAMMA_CONTROL_9, value: 0x0C06);
434 ili922x_write(spi, REG_GAMMA_CONTROL_10, value: 0x0F00);
435 ili922x_write(spi, REG_RAM_ADDRESS_SET, value: 0x0000);
436 ili922x_write(spi, REG_GATE_SCAN_CONTROL, value: 0x0000);
437 ili922x_write(spi, REG_VERT_SCROLL_CONTROL, value: 0x0000);
438 ili922x_write(spi, REG_FIRST_SCREEN_DRIVE_POS, value: 0xDB00);
439 ili922x_write(spi, REG_SECOND_SCREEN_DRIVE_POS, value: 0xDB00);
440 ili922x_write(spi, REG_RAM_ADDR_POS_H, value: 0xAF00);
441 ili922x_write(spi, REG_RAM_ADDR_POS_V, value: 0xDB00);
442 ili922x_reg_dump(spi);
443 set_write_to_gram_reg(spi);
444}
445
446static int ili922x_lcd_power(struct ili922x *lcd, int power)
447{
448 int ret = 0;
449
450 if (POWER_IS_ON(power) && !POWER_IS_ON(lcd->power))
451 ret = ili922x_poweron(spi: lcd->spi);
452 else if (!POWER_IS_ON(power) && POWER_IS_ON(lcd->power))
453 ret = ili922x_poweroff(spi: lcd->spi);
454
455 if (!ret)
456 lcd->power = power;
457
458 return ret;
459}
460
461static int ili922x_set_power(struct lcd_device *ld, int power)
462{
463 struct ili922x *ili = lcd_get_data(ld_dev: ld);
464
465 return ili922x_lcd_power(lcd: ili, power);
466}
467
468static int ili922x_get_power(struct lcd_device *ld)
469{
470 struct ili922x *ili = lcd_get_data(ld_dev: ld);
471
472 return ili->power;
473}
474
475static struct lcd_ops ili922x_ops = {
476 .get_power = ili922x_get_power,
477 .set_power = ili922x_set_power,
478};
479
480static int ili922x_probe(struct spi_device *spi)
481{
482 struct ili922x *ili;
483 struct lcd_device *lcd;
484 int ret;
485 u16 reg = 0;
486
487 ili = devm_kzalloc(dev: &spi->dev, size: sizeof(*ili), GFP_KERNEL);
488 if (!ili)
489 return -ENOMEM;
490
491 ili->spi = spi;
492 spi_set_drvdata(spi, data: ili);
493
494 /* check if the device is connected */
495 ret = ili922x_read(spi, REG_DRIVER_CODE_READ, rx: &reg);
496 if (ret || ((reg & ILITEK_DEVICE_ID_MASK) != ILITEK_DEVICE_ID)) {
497 dev_err(&spi->dev,
498 "no LCD found: Chip ID 0x%x, ret %d\n",
499 reg, ret);
500 return -ENODEV;
501 }
502
503 dev_info(&spi->dev, "ILI%x found, SPI freq %d, mode %d\n",
504 reg, spi->max_speed_hz, spi->mode);
505
506 ret = ili922x_read_status(spi, rs: &reg);
507 if (ret) {
508 dev_err(&spi->dev, "reading RS failed...\n");
509 return ret;
510 }
511
512 dev_dbg(&spi->dev, "status: 0x%x\n", reg);
513
514 ili922x_display_init(spi);
515
516 ili->power = FB_BLANK_POWERDOWN;
517
518 lcd = devm_lcd_device_register(dev: &spi->dev, name: "ili922xlcd", parent: &spi->dev, devdata: ili,
519 ops: &ili922x_ops);
520 if (IS_ERR(ptr: lcd)) {
521 dev_err(&spi->dev, "cannot register LCD\n");
522 return PTR_ERR(ptr: lcd);
523 }
524
525 ili->ld = lcd;
526 spi_set_drvdata(spi, data: ili);
527
528 ili922x_lcd_power(lcd: ili, power: FB_BLANK_UNBLANK);
529
530 return 0;
531}
532
533static void ili922x_remove(struct spi_device *spi)
534{
535 ili922x_poweroff(spi);
536}
537
538static struct spi_driver ili922x_driver = {
539 .driver = {
540 .name = "ili922x",
541 },
542 .probe = ili922x_probe,
543 .remove = ili922x_remove,
544};
545
546module_spi_driver(ili922x_driver);
547
548MODULE_AUTHOR("Stefano Babic <sbabic@denx.de>");
549MODULE_DESCRIPTION("ILI9221/9222 LCD driver");
550MODULE_LICENSE("GPL");
551MODULE_PARM_DESC(ili922x_id, "set controller identifier (default=1)");
552MODULE_PARM_DESC(tx_invert, "invert bytes before sending");
553

source code of linux/drivers/video/backlight/ili922x.c