// SPDX-License-Identifier: GPL-2.0+
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/*
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* FB driver for the SSD1325 OLED Controller
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/gpio.h>
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#include <linux/delay.h>
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#include "fbtft.h"
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#define DRVNAME "fb_ssd1325"
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#define WIDTH 128
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#define HEIGHT 64
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#define GAMMA_NUM 1
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#define GAMMA_LEN 15
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#define DEFAULT_GAMMA "7 1 1 1 1 2 2 3 3 4 4 5 5 6 6"
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/*
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* write_reg() caveat:
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*
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* This doesn't work because D/C has to be LOW for both values:
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* write_reg(par, val1, val2);
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*
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* Do it like this:
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* write_reg(par, val1);
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* write_reg(par, val2);
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*/
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/* Init sequence taken from the Adafruit SSD1306 Arduino library */
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static int init_display(struct fbtft_par *par)
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{
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par->fbtftops.reset(par);
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gpio_set_value(par->gpio.cs, 0);
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write_reg(par, 0xb3);
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write_reg(par, 0xf0);
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write_reg(par, 0xae);
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write_reg(par, 0xa1);
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write_reg(par, 0x00);
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write_reg(par, 0xa8);
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write_reg(par, 0x3f);
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write_reg(par, 0xa0);
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write_reg(par, 0x45);
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write_reg(par, 0xa2);
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write_reg(par, 0x40);
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write_reg(par, 0x75);
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write_reg(par, 0x00);
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write_reg(par, 0x3f);
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write_reg(par, 0x15);
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write_reg(par, 0x00);
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write_reg(par, 0x7f);
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write_reg(par, 0xa4);
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write_reg(par, 0xaf);
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return 0;
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}
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static uint8_t rgb565_to_g16(u16 pixel)
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{
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u16 b = pixel & 0x1f;
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u16 g = (pixel & (0x3f << 5)) >> 5;
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u16 r = (pixel & (0x1f << (5 + 6))) >> (5 + 6);
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pixel = (299 * r + 587 * g + 114 * b) / 195;
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if (pixel > 255)
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pixel = 255;
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return (uint8_t)pixel / 16;
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}
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static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
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{
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fbtft_par_dbg(DEBUG_SET_ADDR_WIN, par,
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"%s(xs=%d, ys=%d, xe=%d, ye=%d)\n", __func__, xs, ys, xe,
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ye);
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write_reg(par, 0x75);
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write_reg(par, 0x00);
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write_reg(par, 0x3f);
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write_reg(par, 0x15);
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write_reg(par, 0x00);
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write_reg(par, 0x7f);
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}
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static int blank(struct fbtft_par *par, bool on)
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{
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fbtft_par_dbg(DEBUG_BLANK, par, "(%s=%s)\n",
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__func__, on ? "true" : "false");
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if (on)
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write_reg(par, 0xAE);
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else
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write_reg(par, 0xAF);
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return 0;
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}
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/*
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* Grayscale Lookup Table
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* GS1 - GS15
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* The "Gamma curve" contains the relative values between the entries
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* in the Lookup table.
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*
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* 0 = Setting of GS1 < Setting of GS2 < Setting of GS3.....<
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* Setting of GS14 < Setting of GS15
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*/
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static int set_gamma(struct fbtft_par *par, u32 *curves)
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{
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int i;
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fbtft_par_dbg(DEBUG_INIT_DISPLAY, par, "%s()\n", __func__);
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for (i = 0; i < GAMMA_LEN; i++) {
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if (i > 0 && curves[i] < 1) {
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dev_err(par->info->device,
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"Illegal value in Grayscale Lookup Table at index %d.\n"
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"Must be greater than 0\n", i);
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return -EINVAL;
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}
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if (curves[i] > 7) {
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dev_err(par->info->device,
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"Illegal value(s) in Grayscale Lookup Table.\n"
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"At index=%d, the accumulated value has exceeded 7\n",
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i);
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return -EINVAL;
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}
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}
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write_reg(par, 0xB8);
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for (i = 0; i < 8; i++)
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write_reg(par, (curves[i] & 0xFF));
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return 0;
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}
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static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
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{
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u16 *vmem16 = (u16 *)par->info->screen_buffer;
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u8 *buf = par->txbuf.buf;
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u8 n1;
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u8 n2;
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int y, x;
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int ret;
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for (x = 0; x < par->info->var.xres; x++) {
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if (x % 2)
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continue;
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for (y = 0; y < par->info->var.yres; y++) {
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n1 = rgb565_to_g16(vmem16[y * par->info->var.xres + x]);
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n2 = rgb565_to_g16(vmem16
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[y * par->info->var.xres + x + 1]);
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*buf = (n1 << 4) | n2;
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buf++;
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}
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}
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gpio_set_value(par->gpio.dc, 1);
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/* Write data */
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ret = par->fbtftops.write(par, par->txbuf.buf,
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par->info->var.xres * par->info->var.yres / 2);
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if (ret < 0)
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dev_err(par->info->device,
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"%s: write failed and returned: %d\n", __func__, ret);
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return ret;
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}
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static struct fbtft_display display = {
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.regwidth = 8,
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.width = WIDTH,
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.height = HEIGHT,
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.txbuflen = WIDTH * HEIGHT / 2,
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.gamma_num = GAMMA_NUM,
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.gamma_len = GAMMA_LEN,
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.gamma = DEFAULT_GAMMA,
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.fbtftops = {
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.write_vmem = write_vmem,
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.init_display = init_display,
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.set_addr_win = set_addr_win,
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.blank = blank,
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.set_gamma = set_gamma,
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},
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};
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FBTFT_REGISTER_DRIVER(DRVNAME, "solomon,ssd1325", &display);
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MODULE_ALIAS("spi:" DRVNAME);
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MODULE_ALIAS("platform:" DRVNAME);
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MODULE_ALIAS("spi:ssd1325");
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MODULE_ALIAS("platform:ssd1325");
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MODULE_DESCRIPTION("SSD1325 OLED Driver");
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MODULE_AUTHOR("Alexey Mednyy");
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MODULE_LICENSE("GPL");
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