fb_ssd1351.c

  1// SPDX-License-Identifier: GPL-2.0
  2
  3#include <linux/backlight.h>
  4#include <linux/module.h>
  5#include <linux/kernel.h>
  6#include <linux/init.h>
  7#include <linux/spi/spi.h>
  8#include <linux/delay.h>
  9#include <linux/string_choices.h>
 10
 11#include "fbtft.h"
 12
 13#define DRVNAME		"fb_ssd1351"
 14#define WIDTH		128
 15#define HEIGHT		128
 16#define GAMMA_NUM	1
 17#define GAMMA_LEN	63
 18#define DEFAULT_GAMMA	"0 2 2 2 2 2 2 2 " \
 19			"2 2 2 2 2 2 2 2 " \
 20			"2 2 2 2 2 2 2 2 " \
 21			"2 2 2 2 2 2 2 2 " \
 22			"2 2 2 2 2 2 2 2 " \
 23			"2 2 2 2 2 2 2 2 " \
 24			"2 2 2 2 2 2 2 2 " \
 25			"2 2 2 2 2 2 2" \
 26
 27static void register_onboard_backlight(struct fbtft_par *par);
 28
 29static int init_display(struct fbtft_par *par)
 30{
 31	if (par->pdata &&
 32	    par->pdata->display.backlight == FBTFT_ONBOARD_BACKLIGHT) {
 33		/* module uses onboard GPIO for panel power */
 34		par->fbtftops.register_backlight = register_onboard_backlight;
 35	}
 36
 37	par->fbtftops.reset(par);
 38
 39	write_reg(par, 0xfd, 0x12); /* Command Lock */
 40	write_reg(par, 0xfd, 0xb1); /* Command Lock */
 41	write_reg(par, 0xae); /* Display Off */
 42	write_reg(par, 0xb3, 0xf1); /* Front Clock Div */
 43	write_reg(par, 0xca, 0x7f); /* Set Mux Ratio */
 44	write_reg(par, 0x15, 0x00, 0x7f); /* Set Column Address */
 45	write_reg(par, 0x75, 0x00, 0x7f); /* Set Row Address */
 46	write_reg(par, 0xa1, 0x00); /* Set Display Start Line */
 47	write_reg(par, 0xa2, 0x00); /* Set Display Offset */
 48	write_reg(par, 0xb5, 0x00); /* Set GPIO */
 49	write_reg(par, 0xab, 0x01); /* Set Function Selection */
 50	write_reg(par, 0xb1, 0x32); /* Set Phase Length */
 51	write_reg(par, 0xb4, 0xa0, 0xb5, 0x55); /* Set Segment Low Voltage */
 52	write_reg(par, 0xbb, 0x17); /* Set Precharge Voltage */
 53	write_reg(par, 0xbe, 0x05); /* Set VComH Voltage */
 54	write_reg(par, 0xc1, 0xc8, 0x80, 0xc8); /* Set Contrast */
 55	write_reg(par, 0xc7, 0x0f); /* Set Master Contrast */
 56	write_reg(par, 0xb6, 0x01); /* Set Second Precharge Period */
 57	write_reg(par, 0xa6); /* Set Display Mode Reset */
 58	write_reg(par, 0xaf); /* Set Sleep Mode Display On */
 59
 60	return 0;
 61}
 62
 63static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
 64{
 65	write_reg(par, 0x15, xs, xe);
 66	write_reg(par, 0x75, ys, ye);
 67	write_reg(par, 0x5c);
 68}
 69
 70static int set_var(struct fbtft_par *par)
 71{
 72	unsigned int remap;
 73
 74	if (par->fbtftops.init_display != init_display) {
 75		/* don't risk messing up register A0h */
 76		return 0;
 77	}
 78
 79	remap = 0x60 | (par->bgr << 2); /* Set Colour Depth */
 80
 81	switch (par->info->var.rotate) {
 82	case 0:
 83		write_reg(par, 0xA0, remap | 0x00 | BIT(4));
 84		break;
 85	case 270:
 86		write_reg(par, 0xA0, remap | 0x03 | BIT(4));
 87		break;
 88	case 180:
 89		write_reg(par, 0xA0, remap | 0x02);
 90		break;
 91	case 90:
 92		write_reg(par, 0xA0, remap | 0x01);
 93		break;
 94	}
 95
 96	return 0;
 97}
 98
 99/*
100 * Grayscale Lookup Table
101 * GS1 - GS63
102 * The driver Gamma curve contains the relative values between the entries
103 * in the Lookup table.
104 *
105 * From datasheet:
106 * 8.8 Gray Scale Decoder
107 *
108 *	there are total 180 Gamma Settings (Setting 0 to Setting 180)
109 *	available for the Gray Scale table.
110 *
111 *	The gray scale is defined in incremental way, with reference
112 *	to the length of previous table entry:
113 *		Setting of GS1 has to be >= 0
114 *		Setting of GS2 has to be > Setting of GS1 +1
115 *		Setting of GS3 has to be > Setting of GS2 +1
116 *		:
117 *		Setting of GS63 has to be > Setting of GS62 +1
118 *
119 */
120static int set_gamma(struct fbtft_par *par, u32 *curves)
121{
122	unsigned long tmp[GAMMA_NUM * GAMMA_LEN];
123	int i, acc = 0;
124
125	for (i = 0; i < 63; i++) {
126		if (i > 0 && curves[i] < 2) {
127			dev_err(par->info->device,
128				"Illegal value in Grayscale Lookup Table at index %d : %d. Must be greater than 1\n",
129				i, curves[i]);
130			return -EINVAL;
131		}
132		acc += curves[i];
133		tmp[i] = acc;
134		if (acc > 180) {
135			dev_err(par->info->device,
136				"Illegal value(s) in Grayscale Lookup Table. At index=%d : %d, the accumulated value has exceeded 180\n",
137				i, acc);
138			return -EINVAL;
139		}
140	}
141
142	write_reg(par, 0xB8,
143		  tmp[0],  tmp[1],  tmp[2],  tmp[3],
144		  tmp[4],  tmp[5],  tmp[6],  tmp[7],
145		  tmp[8],  tmp[9],  tmp[10], tmp[11],
146		  tmp[12], tmp[13], tmp[14], tmp[15],
147		  tmp[16], tmp[17], tmp[18], tmp[19],
148		  tmp[20], tmp[21], tmp[22], tmp[23],
149		  tmp[24], tmp[25], tmp[26], tmp[27],
150		  tmp[28], tmp[29], tmp[30], tmp[31],
151		  tmp[32], tmp[33], tmp[34], tmp[35],
152		  tmp[36], tmp[37], tmp[38], tmp[39],
153		  tmp[40], tmp[41], tmp[42], tmp[43],
154		  tmp[44], tmp[45], tmp[46], tmp[47],
155		  tmp[48], tmp[49], tmp[50], tmp[51],
156		  tmp[52], tmp[53], tmp[54], tmp[55],
157		  tmp[56], tmp[57], tmp[58], tmp[59],
158		  tmp[60], tmp[61], tmp[62]);
159
160	return 0;
161}
162
163static int blank(struct fbtft_par *par, bool on)
164{
165	fbtft_par_dbg(DEBUG_BLANK, par, "(%s=%s)\n",
166		      __func__, str_true_false(on));
167	if (on)
168		write_reg(par, 0xAE);
169	else
170		write_reg(par, 0xAF);
171	return 0;
172}
173
174static struct fbtft_display display = {
175	.regwidth = 8,
176	.width = WIDTH,
177	.height = HEIGHT,
178	.gamma_num = GAMMA_NUM,
179	.gamma_len = GAMMA_LEN,
180	.gamma = DEFAULT_GAMMA,
181	.fbtftops = {
182		.init_display = init_display,
183		.set_addr_win = set_addr_win,
184		.set_var = set_var,
185		.set_gamma = set_gamma,
186		.blank = blank,
187	},
188};
189
190static int update_onboard_backlight(struct backlight_device *bd)
191{
192	struct fbtft_par *par = bl_get_data(bd);
193	bool on;
194
195	fbtft_par_dbg(DEBUG_BACKLIGHT, par, "%s: power=%d\n", __func__, bd->props.power);
196
197	on = !backlight_is_blank(bd);
198	/* Onboard backlight connected to GPIO0 on SSD1351, GPIO1 unused */
199	write_reg(par, 0xB5, on ? 0x03 : 0x02);
200
201	return 0;
202}
203
204static const struct backlight_ops bl_ops = {
205	.update_status = update_onboard_backlight,
206};
207
208static void register_onboard_backlight(struct fbtft_par *par)
209{
210	struct backlight_device *bd;
211	struct backlight_properties bl_props = { 0, };
212
213	bl_props.type = BACKLIGHT_RAW;
214	bl_props.power = BACKLIGHT_POWER_OFF;
215
216	bd = backlight_device_register(dev_driver_string(par->info->device),
217				       par->info->device, par, &bl_ops,
218				       &bl_props);
219	if (IS_ERR(bd)) {
220		dev_err(par->info->device,
221			"cannot register backlight device (%ld)\n",
222			PTR_ERR(bd));
223		return;
224	}
225	par->info->bl_dev = bd;
226
227	if (!par->fbtftops.unregister_backlight)
228		par->fbtftops.unregister_backlight = fbtft_unregister_backlight;
229}
230
231FBTFT_REGISTER_DRIVER(DRVNAME, "solomon,ssd1351", &display);
232
233MODULE_ALIAS("spi:" DRVNAME);
234MODULE_ALIAS("platform:" DRVNAME);
235MODULE_ALIAS("spi:ssd1351");
236MODULE_ALIAS("platform:ssd1351");
237
238MODULE_DESCRIPTION("SSD1351 OLED Driver");
239MODULE_AUTHOR("James Davies");
240MODULE_LICENSE("GPL");