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linux-next/drivers/video/ssd1307fb.c
Maxime Ripard 301bc0675b video: ssd1307fb: Make use of horizontal addressing mode 
By default, the ssd1307 controller uses an addressing mode called page
addressing. This mode only increments the column cursor in memory when
writing data but will not increments the page cursor when we are at the
end of the page.

However, the controller supports another addressing mode, called
horizontal addressing, that will maintain both the page and column
cursors when writing data to the controller.

That means that we can just remove the code that increments the current
page address and reset the column cursor when reaching the end of the
line, allowing to have a lower data overhead, and a simpler driver.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
2013-05-28 14:41:58 +03:00

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/*
* Driver for the Solomon SSD1307 OLED controller
*
* Copyright 2012 Free Electrons
*
* Licensed under the GPLv2 or later.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/i2c.h>
#include <linux/fb.h>
#include <linux/uaccess.h>
#include <linux/of_device.h>
#include <linux/of_gpio.h>
#include <linux/pwm.h>
#include <linux/delay.h>
#define SSD1307FB_DATA 0x40
#define SSD1307FB_COMMAND 0x80
#define SSD1307FB_SET_ADDRESS_MODE 0x20
#define SSD1307FB_SET_ADDRESS_MODE_HORIZONTAL (0x00)
#define SSD1307FB_SET_ADDRESS_MODE_VERTICAL (0x01)
#define SSD1307FB_SET_ADDRESS_MODE_PAGE (0x02)
#define SSD1307FB_SET_COL_RANGE 0x21
#define SSD1307FB_SET_PAGE_RANGE 0x22
#define SSD1307FB_CONTRAST 0x81
#define SSD1307FB_CHARGE_PUMP 0x8d
#define SSD1307FB_SEG_REMAP_ON 0xa1
#define SSD1307FB_DISPLAY_OFF 0xae
#define SSD1307FB_SET_MULTIPLEX_RATIO 0xa8
#define SSD1307FB_DISPLAY_ON 0xaf
#define SSD1307FB_START_PAGE_ADDRESS 0xb0
#define SSD1307FB_SET_DISPLAY_OFFSET 0xd3
#define SSD1307FB_SET_CLOCK_FREQ 0xd5
#define SSD1307FB_SET_PRECHARGE_PERIOD 0xd9
#define SSD1307FB_SET_COM_PINS_CONFIG 0xda
#define SSD1307FB_SET_VCOMH 0xdb
struct ssd1307fb_par;
struct ssd1307fb_ops {
int (*init)(struct ssd1307fb_par *);
int (*remove)(struct ssd1307fb_par *);
};
struct ssd1307fb_par {
struct i2c_client *client;
u32 height;
struct fb_info *info;
struct ssd1307fb_ops *ops;
u32 page_offset;
struct pwm_device *pwm;
u32 pwm_period;
int reset;
u32 width;
};
struct ssd1307fb_array {
u8 type;
u8 data[0];
};
static struct fb_fix_screeninfo ssd1307fb_fix = {
.id = "Solomon SSD1307",
.type = FB_TYPE_PACKED_PIXELS,
.visual = FB_VISUAL_MONO10,
.xpanstep = 0,
.ypanstep = 0,
.ywrapstep = 0,
.accel = FB_ACCEL_NONE,
};
static struct fb_var_screeninfo ssd1307fb_var = {
.bits_per_pixel = 1,
};
static struct ssd1307fb_array *ssd1307fb_alloc_array(u32 len, u8 type)
{
struct ssd1307fb_array *array;
array = kzalloc(sizeof(struct ssd1307fb_array) + len, GFP_KERNEL);
if (!array)
return NULL;
array->type = type;
return array;
}
static int ssd1307fb_write_array(struct i2c_client *client,
struct ssd1307fb_array *array, u32 len)
{
int ret;
len += sizeof(struct ssd1307fb_array);
ret = i2c_master_send(client, (u8 *)array, len);
if (ret != len) {
dev_err(&client->dev, "Couldn't send I2C command.\n");
return ret;
}
return 0;
}
static inline int ssd1307fb_write_cmd(struct i2c_client *client, u8 cmd)
{
struct ssd1307fb_array *array;
int ret;
array = ssd1307fb_alloc_array(1, SSD1307FB_COMMAND);
if (!array)
return -ENOMEM;
array->data[0] = cmd;
ret = ssd1307fb_write_array(client, array, 1);
kfree(array);
return ret;
}
static inline int ssd1307fb_write_data(struct i2c_client *client, u8 data)
{
struct ssd1307fb_array *array;
int ret;
array = ssd1307fb_alloc_array(1, SSD1307FB_DATA);
if (!array)
return -ENOMEM;
array->data[0] = data;
ret = ssd1307fb_write_array(client, array, 1);
kfree(array);
return ret;
}
static void ssd1307fb_update_display(struct ssd1307fb_par *par)
{
struct ssd1307fb_array *array;
u8 *vmem = par->info->screen_base;
int i, j, k;
array = ssd1307fb_alloc_array(par->width * par->height / 8,
SSD1307FB_DATA);
if (!array)
return;
/*
* The screen is divided in pages, each having a height of 8
* pixels, and the width of the screen. When sending a byte of
* data to the controller, it gives the 8 bits for the current
* column. I.e, the first byte are the 8 bits of the first
* column, then the 8 bits for the second column, etc.
*
*
* Representation of the screen, assuming it is 5 bits
* wide. Each letter-number combination is a bit that controls
* one pixel.
*
* A0 A1 A2 A3 A4
* B0 B1 B2 B3 B4
* C0 C1 C2 C3 C4
* D0 D1 D2 D3 D4
* E0 E1 E2 E3 E4
* F0 F1 F2 F3 F4
* G0 G1 G2 G3 G4
* H0 H1 H2 H3 H4
*
* If you want to update this screen, you need to send 5 bytes:
* (1) A0 B0 C0 D0 E0 F0 G0 H0
* (2) A1 B1 C1 D1 E1 F1 G1 H1
* (3) A2 B2 C2 D2 E2 F2 G2 H2
* (4) A3 B3 C3 D3 E3 F3 G3 H3
* (5) A4 B4 C4 D4 E4 F4 G4 H4
*/
for (i = 0; i < (par->height / 8); i++) {
for (j = 0; j < par->width; j++) {
u32 array_idx = i * par->width + j;
array->data[array_idx] = 0;
for (k = 0; k < 8; k++) {
u32 page_length = par->width * i;
u32 index = page_length + (par->width * k + j) / 8;
u8 byte = *(vmem + index);
u8 bit = byte & (1 << (j % 8));
bit = bit >> (j % 8);
array->data[array_idx] |= bit << k;
}
}
}
ssd1307fb_write_array(par->client, array, par->width * par->height / 8);
kfree(array);
}
static ssize_t ssd1307fb_write(struct fb_info *info, const char __user *buf,
size_t count, loff_t *ppos)
{
struct ssd1307fb_par *par = info->par;
unsigned long total_size;
unsigned long p = *ppos;
u8 __iomem *dst;
total_size = info->fix.smem_len;
if (p > total_size)
return -EINVAL;
if (count + p > total_size)
count = total_size - p;
if (!count)
return -EINVAL;
dst = (void __force *) (info->screen_base + p);
if (copy_from_user(dst, buf, count))
return -EFAULT;
ssd1307fb_update_display(par);
*ppos += count;
return count;
}
static void ssd1307fb_fillrect(struct fb_info *info, const struct fb_fillrect *rect)
{
struct ssd1307fb_par *par = info->par;
sys_fillrect(info, rect);
ssd1307fb_update_display(par);
}
static void ssd1307fb_copyarea(struct fb_info *info, const struct fb_copyarea *area)
{
struct ssd1307fb_par *par = info->par;
sys_copyarea(info, area);
ssd1307fb_update_display(par);
}
static void ssd1307fb_imageblit(struct fb_info *info, const struct fb_image *image)
{
struct ssd1307fb_par *par = info->par;
sys_imageblit(info, image);
ssd1307fb_update_display(par);
}
static struct fb_ops ssd1307fb_ops = {
.owner = THIS_MODULE,
.fb_read = fb_sys_read,
.fb_write = ssd1307fb_write,
.fb_fillrect = ssd1307fb_fillrect,
.fb_copyarea = ssd1307fb_copyarea,
.fb_imageblit = ssd1307fb_imageblit,
};
static void ssd1307fb_deferred_io(struct fb_info *info,
struct list_head *pagelist)
{
ssd1307fb_update_display(info->par);
}
static struct fb_deferred_io ssd1307fb_defio = {
.delay = HZ,
.deferred_io = ssd1307fb_deferred_io,
};
static int ssd1307fb_ssd1307_init(struct ssd1307fb_par *par)
{
int ret;
par->pwm = pwm_get(&par->client->dev, NULL);
if (IS_ERR(par->pwm)) {
dev_err(&par->client->dev, "Could not get PWM from device tree!\n");
return PTR_ERR(par->pwm);
}
par->pwm_period = pwm_get_period(par->pwm);
/* Enable the PWM */
pwm_config(par->pwm, par->pwm_period / 2, par->pwm_period);
pwm_enable(par->pwm);
dev_dbg(&par->client->dev, "Using PWM%d with a %dns period.\n",
par->pwm->pwm, par->pwm_period);
/* Map column 127 of the OLED to segment 0 */
ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SEG_REMAP_ON);
if (ret < 0)
return ret;
/* Turn on the display */
ret = ssd1307fb_write_cmd(par->client, SSD1307FB_DISPLAY_ON);
if (ret < 0)
return ret;
return 0;
}
static int ssd1307fb_ssd1307_remove(struct ssd1307fb_par *par)
{
pwm_disable(par->pwm);
pwm_put(par->pwm);
return 0;
}
static struct ssd1307fb_ops ssd1307fb_ssd1307_ops = {
.init = ssd1307fb_ssd1307_init,
.remove = ssd1307fb_ssd1307_remove,
};
static int ssd1307fb_ssd1306_init(struct ssd1307fb_par *par)
{
int ret;
/* Set initial contrast */
ret = ssd1307fb_write_cmd(par->client, SSD1307FB_CONTRAST);
ret = ret & ssd1307fb_write_cmd(par->client, 0x7f);
if (ret < 0)
return ret;
/* Set COM direction */
ret = ssd1307fb_write_cmd(par->client, 0xc8);
if (ret < 0)
return ret;
/* Set segment re-map */
ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SEG_REMAP_ON);
if (ret < 0)
return ret;
/* Set multiplex ratio value */
ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_MULTIPLEX_RATIO);
ret = ret & ssd1307fb_write_cmd(par->client, par->height - 1);
if (ret < 0)
return ret;
/* set display offset value */
ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_DISPLAY_OFFSET);
ret = ssd1307fb_write_cmd(par->client, 0x20);
if (ret < 0)
return ret;
/* Set clock frequency */
ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_CLOCK_FREQ);
ret = ret & ssd1307fb_write_cmd(par->client, 0xf0);
if (ret < 0)
return ret;
/* Set precharge period in number of ticks from the internal clock */
ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_PRECHARGE_PERIOD);
ret = ret & ssd1307fb_write_cmd(par->client, 0x22);
if (ret < 0)
return ret;
/* Set COM pins configuration */
ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_COM_PINS_CONFIG);
ret = ret & ssd1307fb_write_cmd(par->client, 0x22);
if (ret < 0)
return ret;
/* Set VCOMH */
ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_VCOMH);
ret = ret & ssd1307fb_write_cmd(par->client, 0x49);
if (ret < 0)
return ret;
/* Turn on the DC-DC Charge Pump */
ret = ssd1307fb_write_cmd(par->client, SSD1307FB_CHARGE_PUMP);
ret = ret & ssd1307fb_write_cmd(par->client, 0x14);
if (ret < 0)
return ret;
/* Switch to horizontal addressing mode */
ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_ADDRESS_MODE);
ret = ret & ssd1307fb_write_cmd(par->client,
SSD1307FB_SET_ADDRESS_MODE_HORIZONTAL);
if (ret < 0)
return ret;
ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_COL_RANGE);
ret = ret & ssd1307fb_write_cmd(par->client, 0x0);
ret = ret & ssd1307fb_write_cmd(par->client, par->width - 1);
if (ret < 0)
return ret;
ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_PAGE_RANGE);
ret = ret & ssd1307fb_write_cmd(par->client, 0x0);
ret = ret & ssd1307fb_write_cmd(par->client,
par->page_offset + (par->height / 8) - 1);
if (ret < 0)
return ret;
/* Turn on the display */
ret = ssd1307fb_write_cmd(par->client, SSD1307FB_DISPLAY_ON);
if (ret < 0)
return ret;
return 0;
}
static struct ssd1307fb_ops ssd1307fb_ssd1306_ops = {
.init = ssd1307fb_ssd1306_init,
};
static const struct of_device_id ssd1307fb_of_match[] = {
{
.compatible = "solomon,ssd1306fb-i2c",
.data = (void *)&ssd1307fb_ssd1306_ops,
},
{
.compatible = "solomon,ssd1307fb-i2c",
.data = (void *)&ssd1307fb_ssd1307_ops,
},
{},
};
MODULE_DEVICE_TABLE(of, ssd1307fb_of_match);
static int ssd1307fb_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct fb_info *info;
struct device_node *node = client->dev.of_node;
u32 vmem_size;
struct ssd1307fb_par *par;
u8 *vmem;
int ret;
if (!node) {
dev_err(&client->dev, "No device tree data found!\n");
return -EINVAL;
}
info = framebuffer_alloc(sizeof(struct ssd1307fb_par), &client->dev);
if (!info) {
dev_err(&client->dev, "Couldn't allocate framebuffer.\n");
return -ENOMEM;
}
par = info->par;
par->info = info;
par->client = client;
par->ops = (struct ssd1307fb_ops *)of_match_device(ssd1307fb_of_match,
&client->dev)->data;
par->reset = of_get_named_gpio(client->dev.of_node,
"reset-gpios", 0);
if (!gpio_is_valid(par->reset)) {
ret = -EINVAL;
goto fb_alloc_error;
}
if (of_property_read_u32(node, "solomon,width", &par->width))
par->width = 96;
if (of_property_read_u32(node, "solomon,height", &par->height))
par->width = 16;
if (of_property_read_u32(node, "solomon,page-offset", &par->page_offset))
par->page_offset = 1;
vmem_size = par->width * par->height / 8;
vmem = devm_kzalloc(&client->dev, vmem_size, GFP_KERNEL);
if (!vmem) {
dev_err(&client->dev, "Couldn't allocate graphical memory.\n");
ret = -ENOMEM;
goto fb_alloc_error;
}
info->fbops = &ssd1307fb_ops;
info->fix = ssd1307fb_fix;
info->fix.line_length = par->width / 8;
info->fbdefio = &ssd1307fb_defio;
info->var = ssd1307fb_var;
info->var.xres = par->width;
info->var.xres_virtual = par->width;
info->var.yres = par->height;
info->var.yres_virtual = par->height;
info->var.red.length = 1;
info->var.red.offset = 0;
info->var.green.length = 1;
info->var.green.offset = 0;
info->var.blue.length = 1;
info->var.blue.offset = 0;
info->screen_base = (u8 __force __iomem *)vmem;
info->fix.smem_start = (unsigned long)vmem;
info->fix.smem_len = vmem_size;
fb_deferred_io_init(info);
ret = devm_gpio_request_one(&client->dev, par->reset,
GPIOF_OUT_INIT_HIGH,
"oled-reset");
if (ret) {
dev_err(&client->dev,
"failed to request gpio %d: %d\n",
par->reset, ret);
goto reset_oled_error;
}
i2c_set_clientdata(client, info);
/* Reset the screen */
gpio_set_value(par->reset, 0);
udelay(4);
gpio_set_value(par->reset, 1);
udelay(4);
if (par->ops->init) {
ret = par->ops->init(par);
if (ret)
goto reset_oled_error;
}
ret = register_framebuffer(info);
if (ret) {
dev_err(&client->dev, "Couldn't register the framebuffer\n");
goto panel_init_error;
}
dev_info(&client->dev, "fb%d: %s framebuffer device registered, using %d bytes of video memory\n", info->node, info->fix.id, vmem_size);
return 0;
panel_init_error:
if (par->ops->remove)
par->ops->remove(par);
reset_oled_error:
fb_deferred_io_cleanup(info);
fb_alloc_error:
framebuffer_release(info);
return ret;
}
static int ssd1307fb_remove(struct i2c_client *client)
{
struct fb_info *info = i2c_get_clientdata(client);
struct ssd1307fb_par *par = info->par;
unregister_framebuffer(info);
if (par->ops->remove)
par->ops->remove(par);
fb_deferred_io_cleanup(info);
framebuffer_release(info);
return 0;
}
static const struct i2c_device_id ssd1307fb_i2c_id[] = {
{ "ssd1306fb", 0 },
{ "ssd1307fb", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, ssd1307fb_i2c_id);
static struct i2c_driver ssd1307fb_driver = {
.probe = ssd1307fb_probe,
.remove = ssd1307fb_remove,
.id_table = ssd1307fb_i2c_id,
.driver = {
.name = "ssd1307fb",
.of_match_table = of_match_ptr(ssd1307fb_of_match),
.owner = THIS_MODULE,
},
};
module_i2c_driver(ssd1307fb_driver);
MODULE_DESCRIPTION("FB driver for the Solomon SSD1307 OLED controller");
MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
MODULE_LICENSE("GPL");
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