1/*
2 * FB driver for the PCD8544 LCD Controller
3 *
4 * The display is monochrome and the video memory is RGB565.
5 * Any pixel value except 0 turns the pixel on.
6 *
7 * Copyright (C) 2013 Noralf Tronnes
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
22 */
23
24#include <linux/module.h>
25#include <linux/kernel.h>
26#include <linux/init.h>
27#include <linux/gpio.h>
28#include <linux/spi/spi.h>
29#include <linux/delay.h>
30
31#include "fbtft.h"
32
33#define DRVNAME	       "fb_pcd8544"
34#define WIDTH          84
35#define HEIGHT         48
36#define TXBUFLEN       (84*6)
37#define DEFAULT_GAMMA  "40" /* gamma controls the contrast in this driver */
38
39static unsigned tc;
40module_param(tc, uint, 0);
41MODULE_PARM_DESC(tc, "TC[1:0] Temperature coefficient: 0-3 (default: 0)");
42
43static unsigned bs = 4;
44module_param(bs, uint, 0);
45MODULE_PARM_DESC(bs, "BS[2:0] Bias voltage level: 0-7 (default: 4)");
46
47
48static int init_display(struct fbtft_par *par)
49{
50	fbtft_par_dbg(DEBUG_INIT_DISPLAY, par, "%s()\n", __func__);
51
52	par->fbtftops.reset(par);
53
54	/* Function set
55	 *
56	 * 5:1  1
57	 * 2:0  PD - Powerdown control: chip is active
58	 * 1:0  V  - Entry mode: horizontal addressing
59	 * 0:1  H  - Extended instruction set control: extended
60	 */
61	write_reg(par, 0x21);
62
63	/* H=1 Temperature control
64	 *
65	 * 2:1  1
66	 * 1:x  TC1 - Temperature Coefficient: 0x10
67	 * 0:x  TC0
68	 */
69	write_reg(par, 0x04 | (tc & 0x3));
70
71	/* H=1 Bias system
72	 *
73	 * 4:1  1
74	 * 3:0  0
75	 * 2:x  BS2 - Bias System
76	 * 1:x  BS1
77	 * 0:x  BS0
78	 */
79	write_reg(par, 0x10 | (bs & 0x7));
80
81	/* Function set
82	 *
83	 * 5:1  1
84	 * 2:0  PD - Powerdown control: chip is active
85	 * 1:1  V  - Entry mode: vertical addressing
86	 * 0:0  H  - Extended instruction set control: basic
87	 */
88	write_reg(par, 0x22);
89
90	/* H=0 Display control
91	 *
92	 * 3:1  1
93	 * 2:1  D  - DE: 10=normal mode
94	 * 1:0  0
95	 * 0:0  E
96	 */
97	write_reg(par, 0x08 | 4);
98
99	return 0;
100}
101
102static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
103{
104	fbtft_par_dbg(DEBUG_SET_ADDR_WIN, par, "%s(xs=%d, ys=%d, xe=%d, ye=%d)\n",
105		      __func__, xs, ys, xe, ye);
106
107	/* H=0 Set X address of RAM
108	 *
109	 * 7:1  1
110	 * 6-0: X[6:0] - 0x00
111	 */
112	write_reg(par, 0x80);
113
114	/* H=0 Set Y address of RAM
115	 *
116	 * 7:0  0
117	 * 6:1  1
118	 * 2-0: Y[2:0] - 0x0
119	 */
120	write_reg(par, 0x40);
121}
122
123static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
124{
125	u16 *vmem16 = (u16 *)par->info->screen_base;
126	u8 *buf = par->txbuf.buf;
127	int x, y, i;
128	int ret = 0;
129
130	fbtft_par_dbg(DEBUG_WRITE_VMEM, par, "%s()\n", __func__);
131
132	for (x = 0; x < 84; x++) {
133		for (y = 0; y < 6; y++) {
134			*buf = 0x00;
135			for (i = 0; i < 8; i++)
136				*buf |= (vmem16[(y*8+i)*84+x] ? 1 : 0) << i;
137			buf++;
138		}
139	}
140
141	/* Write data */
142	gpio_set_value(par->gpio.dc, 1);
143	ret = par->fbtftops.write(par, par->txbuf.buf, 6*84);
144	if (ret < 0)
145		dev_err(par->info->device, "write failed and returned: %d\n",
146			ret);
147
148	return ret;
149}
150
151static int set_gamma(struct fbtft_par *par, unsigned long *curves)
152{
153	fbtft_par_dbg(DEBUG_INIT_DISPLAY, par, "%s()\n", __func__);
154
155	/* apply mask */
156	curves[0] &= 0x7F;
157
158	write_reg(par, 0x23); /* turn on extended instruction set */
159	write_reg(par, 0x80 | curves[0]);
160	write_reg(par, 0x22); /* turn off extended instruction set */
161
162	return 0;
163}
164
165
166static struct fbtft_display display = {
167	.regwidth = 8,
168	.width = WIDTH,
169	.height = HEIGHT,
170	.txbuflen = TXBUFLEN,
171	.gamma_num = 1,
172	.gamma_len = 1,
173	.gamma = DEFAULT_GAMMA,
174	.fbtftops = {
175		.init_display = init_display,
176		.set_addr_win = set_addr_win,
177		.write_vmem = write_vmem,
178		.set_gamma = set_gamma,
179	},
180	.backlight = 1,
181};
182FBTFT_REGISTER_DRIVER(DRVNAME, "philips,pdc8544", &display);
183
184MODULE_ALIAS("spi:" DRVNAME);
185MODULE_ALIAS("spi:pdc8544");
186
187MODULE_DESCRIPTION("FB driver for the PCD8544 LCD Controller");
188MODULE_AUTHOR("Noralf Tronnes");
189MODULE_LICENSE("GPL");
190