2 * FB driver for the PCD8544 LCD Controller
4 * The display is monochrome and the video memory is RGB565.
5 * Any pixel value except 0 turns the pixel on.
7 * Copyright (C) 2013 Noralf Tronnes
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.
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.
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.
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>
33 #define DRVNAME "fb_pcd8544"
36 #define TXBUFLEN (84*6)
37 #define DEFAULT_GAMMA "40" /* gamma is used to control contrast in this driver */
40 module_param(tc
, uint
, 0);
41 MODULE_PARM_DESC(tc
, "TC[1:0] Temperature coefficient: 0-3 (default: 0)");
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)");
48 static int init_display(struct fbtft_par
*par
)
50 fbtft_par_dbg(DEBUG_INIT_DISPLAY
, par
, "%s()\n", __func__
);
52 par
->fbtftops
.reset(par
);
55 write_reg(par
, 0x21); /* 5:1 1
56 2:0 PD - Powerdown control: chip is active
57 1:0 V - Entry mode: horizontal addressing
58 0:1 H - Extended instruction set control: extended
61 /* H=1 Temperature control */
62 write_reg(par
, 0x04 | (tc
& 0x3)); /*
64 1:x TC1 - Temperature Coefficient: 0x10
69 write_reg(par
, 0x10 | (bs
& 0x7)); /*
78 write_reg(par
, 0x22); /* 5:1 1
79 2:0 PD - Powerdown control: chip is active
80 1:1 V - Entry mode: vertical addressing
81 0:0 H - Extended instruction set control: basic
84 /* H=0 Display control */
85 write_reg(par
, 0x08 | 4); /*
87 2:1 D - DE: 10=normal mode
95 static void set_addr_win(struct fbtft_par
*par
, int xs
, int ys
, int xe
, int ye
)
97 fbtft_par_dbg(DEBUG_SET_ADDR_WIN
, par
, "%s(xs=%d, ys=%d, xe=%d, ye=%d)\n", __func__
, xs
, ys
, xe
, ye
);
99 /* H=0 Set X address of RAM */
100 write_reg(par
, 0x80); /* 7:1 1
104 /* H=0 Set Y address of RAM */
105 write_reg(par
, 0x40); /* 7:0 0
111 static int write_vmem(struct fbtft_par
*par
, size_t offset
, size_t len
)
113 u16
*vmem16
= (u16
*)par
->info
->screen_base
;
114 u8
*buf
= par
->txbuf
.buf
;
118 fbtft_par_dbg(DEBUG_WRITE_VMEM
, par
, "%s()\n", __func__
);
120 for (x
= 0; x
< 84; x
++) {
121 for (y
= 0; y
< 6; y
++) {
123 for (i
= 0; i
< 8; i
++) {
124 *buf
|= (vmem16
[(y
*8+i
)*84+x
] ? 1 : 0) << i
;
131 gpio_set_value(par
->gpio
.dc
, 1);
132 ret
= par
->fbtftops
.write(par
, par
->txbuf
.buf
, 6*84);
134 dev_err(par
->info
->device
, "%s: write failed and returned: %d\n", __func__
, ret
);
139 static int set_gamma(struct fbtft_par
*par
, unsigned long *curves
)
141 fbtft_par_dbg(DEBUG_INIT_DISPLAY
, par
, "%s()\n", __func__
);
146 write_reg(par
, 0x23); /* turn on extended instruction set */
147 write_reg(par
, 0x80 | curves
[0]);
148 write_reg(par
, 0x22); /* turn off extended instruction set */
154 static struct fbtft_display display
= {
158 .txbuflen
= TXBUFLEN
,
161 .gamma
= DEFAULT_GAMMA
,
163 .init_display
= init_display
,
164 .set_addr_win
= set_addr_win
,
165 .write_vmem
= write_vmem
,
166 .set_gamma
= set_gamma
,
170 FBTFT_REGISTER_DRIVER(DRVNAME
, "philips,pdc8544", &display
);
172 MODULE_ALIAS("spi:" DRVNAME
);
173 MODULE_ALIAS("spi:pdc8544");
175 MODULE_DESCRIPTION("FB driver for the PCD8544 LCD Controller");
176 MODULE_AUTHOR("Noralf Tronnes");
177 MODULE_LICENSE("GPL");
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