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
39 static unsigned tc;
40 module_param(tc, uint, 0);
41 MODULE_PARM_DESC(tc, "TC[1:0] Temperature coefficient: 0-3 (default: 0)");
42
43 static unsigned bs = 4;
44 module_param(bs, uint, 0);
45 MODULE_PARM_DESC(bs, "BS[2:0] Bias voltage level: 0-7 (default: 4)");
46
47
init_display(struct fbtft_par * par)48 static 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
set_addr_win(struct fbtft_par * par,int xs,int ys,int xe,int ye)102 static 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
write_vmem(struct fbtft_par * par,size_t offset,size_t len)123 static 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
set_gamma(struct fbtft_par * par,unsigned long * curves)151 static 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
166 static 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 };
182 FBTFT_REGISTER_DRIVER(DRVNAME, "philips,pdc8544", &display);
183
184 MODULE_ALIAS("spi:" DRVNAME);
185 MODULE_ALIAS("spi:pdc8544");
186
187 MODULE_DESCRIPTION("FB driver for the PCD8544 LCD Controller");
188 MODULE_AUTHOR("Noralf Tronnes");
189 MODULE_LICENSE("GPL");
190