[PATCH 1/4] video: Add support for the Solomon SSD1307 OLED Controller

Jingoo Han
2012-08-01T05:44:16Z

On Tuesday, July 31, 2012 7:30 PM Maxime Ripard wrote:
>
> This patch adds support for the Solomon SSD1307 OLED
> controller found on the Crystalfontz CFA10036 board.
>
> This controller can drive a display with a resolution up
> to 128x39 and can operate over I2C or SPI.
>
> The current driver has only been tested on the CFA-10036,
> that is using this controller over I2C to driver a 96x16
> OLED screen.
>
> Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
> Cc: Brian Lilly <brian@crystalfontz.com>
> ---
> .../devicetree/bindings/video/ssd1307fb.txt | 24 ++
> drivers/video/Kconfig | 14 +
> drivers/video/Makefile | 1 +
> drivers/video/ssd1307fb.c | 418 ++++++++++++++++++++
> 4 files changed, 457 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/video/ssd1307fb.txt
> create mode 100644 drivers/video/ssd1307fb.c
>
> diff --git a/Documentation/devicetree/bindings/video/ssd1307fb.txt
> b/Documentation/devicetree/bindings/video/ssd1307fb.txt
> new file mode 100644
> index 0000000..791e14f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/video/ssd1307fb.txt
> @@ -0,0 +1,24 @@
> +* Solomon SSD1307 Framebuffer Driver
> +
> +Required properties:
> + - compatible: Should be "solomon,ssd1307fb-<bus>". The only supported bus for
> + now is i2c.
> + - reg: Should contain address of the controller on the I2C bus. Most likely
> + 0x3c or 0x3d
> + - pwm: Should contain the pwm to use according to the OF device tree PWM
> + specification [0]
> + - oled-reset-gpio: Should contain the GPIO used to reset the OLED display
> +
> +Optional properties:
> + - oled-reset-active-low: Is the reset gpio is active on physical low?
> +
> +[0]: Documentation/devicetree/bindings/pwm/pwm.txt
> +
> +Examples:
> +ssd1307: oled at 3c {
> + compatible = "solomon,ssd1307fb-i2c";
> + reg = <0x3c>;
> + pwms = <&pwm 4 3000>;
> + oled-reset-gpio = <&gpio2 7 1>;
> + oled-reset-active-low;
> +};
> diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
> index 0217f74..21ae6dd 100644
> --- a/drivers/video/Kconfig
> +++ b/drivers/video/Kconfig
> @@ -2469,4 +2469,18 @@ config FB_SH_MOBILE_MERAM
> Up to 4 memory channels can be configured, allowing 4 RGB or
> 2 YCbCr framebuffers to be configured.
>
> +

Please remove redundant line.

> +config FB_SSD1307
> + tristate "Solomon SSD1307 framebuffer support"
> + depends on FB && I2C
> + select FB_SYS_FOPS
> + select FB_SYS_FILLRECT
> + select FB_SYS_COPYAREA
> + select FB_SYS_IMAGEBLIT
> + select FB_DEFERRED_IO
> + select PWM
> + help
> + This driver implements support for the Solomon SSD1307
> + OLED controller over I2C.
> +
> endmenu
> diff --git a/drivers/video/Makefile b/drivers/video/Makefile
> index ee8dafb..6bbb72c 100644
> --- a/drivers/video/Makefile
> +++ b/drivers/video/Makefile
> @@ -164,6 +164,7 @@ obj-$(CONFIG_FB_BFIN_7393) += bfin_adv7393fb.o
> obj-$(CONFIG_FB_MX3) += mx3fb.o
> obj-$(CONFIG_FB_DA8XX) += da8xx-fb.o
> obj-$(CONFIG_FB_MXS) += mxsfb.o
> +obj-$(CONFIG_FB_SSD1307) += ssd1307fb.o
>
> # the test framebuffer is last
> obj-$(CONFIG_FB_VIRTUAL) += vfb.o
> diff --git a/drivers/video/ssd1307fb.c b/drivers/video/ssd1307fb.c
> new file mode 100644
> index 0000000..c705ab4
> --- /dev/null
> +++ b/drivers/video/ssd1307fb.c
> @@ -0,0 +1,418 @@
> +/*
> + * Driver for the Solomon SSD1307 OLED controler
> + *
> + * 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_WIDTH 96
> +#define SSD1307FB_HEIGHT 16
> +
> +#define SSD1307FB_DATA 0x40
> +#define SSD1307FB_COMMAND 0x80
> +
> +#define SSD1307FB_CONTRAST 0x81
> +#define SSD1307FB_SEG_REMAP_ON 0xa1
> +#define SSD1307FB_DISPLAY_OFF 0xae
> +#define SSD1307FB_DISPLAY_ON 0xaf
> +#define SSD1307FB_START_PAGE_ADDRESS 0xb0
> +
> +struct ssd1307fb_par {
> + struct i2c_client *client;
> + struct fb_info *info;
> + struct pwm_device *pwm;
> + u32 pwm_period;
> + int reset;
> +};
> +
> +static struct fb_fix_screeninfo ssd1307fb_fix __devinitdata = {
> + .id = "Solomon SSD1307",
> + .type = FB_TYPE_PACKED_PIXELS,
> + .visual = FB_VISUAL_MONO10,
> + .xpanstep = 0,
> + .ypanstep = 0,
> + .ywrapstep = 0,
> + .line_length = SSD1307FB_WIDTH / 8,
> + .accel = FB_ACCEL_NONE,
> +};
> +
> +static struct fb_var_screeninfo ssd1307fb_var __devinitdata = {
> + .xres = SSD1307FB_WIDTH,
> + .yres = SSD1307FB_HEIGHT,
> + .xres_virtual = SSD1307FB_WIDTH,
> + .yres_virtual = SSD1307FB_HEIGHT,
> + .bits_per_pixel = 1,
> +};
> +
> +static int ssd1307fb_write_array(struct i2c_client *client, u8 type, u8* cmd, u32 len)
> +{
> + u8 *buf;
> + int ret = 0;
> +
> + buf = kzalloc(len + 1, GFP_KERNEL);
> + if (!buf) {
> + dev_err(&client->dev, "Couldn't allocate sending buffer.\n");
> + ret = -ENOMEM;
> + goto out;
> + }

How about using returning - ENOMEM without goto.
It is simpler.

if (!buf) {
dev_err(&client->dev, "Couldn't allocate sending buffer.\n");
return -ENOMEM;
}

> +
> + buf[0] = type;
> + memcpy(buf + 1, cmd, len);
> +
> + ret = i2c_master_send(client, buf, len + 1);
> + if (ret != len + 1) {
> + dev_err(&client->dev, "Couldn't send I2C command.\n");
> + goto error;
> + }
> +
> +error:
> + kfree(buf);
> +out:
> + return ret;

Please refer to above comment.
If goto out is not used, it would be simpler.

+error:
+ kfree(buf);
+ return ret;

> +}
> +
> +static inline int ssd1307fb_write_cmd_array(struct i2c_client *client, u8* cmd, u32 len)
> +{
> + return ssd1307fb_write_array(client, SSD1307FB_COMMAND, cmd, len);
> +}
> +
> +static inline int ssd1307fb_write_cmd(struct i2c_client *client, u8 cmd)
> +{
> + return ssd1307fb_write_cmd_array(client, &cmd, 1);
> +}
> +
> +static inline int ssd1307fb_write_data_array(struct i2c_client *client, u8* cmd, u32 len)
> +{
> + return ssd1307fb_write_array(client, SSD1307FB_DATA, cmd, len);
> +}
> +
> +static inline int ssd1307fb_write_data(struct i2c_client *client, u8 data)
> +{
> + return ssd1307fb_write_data_array(client, &data, 1);
> +}
> +
> +static int ssd1307fb_set(struct i2c_client *client, u8 value)
> +{
> + int i, j, ret;
> +
> + for (i = 1; i <= (SSD1307FB_HEIGHT / 8); i++) {
> + ret = ssd1307fb_write_cmd(client, SSD1307FB_START_PAGE_ADDRESS + i);
> + if (ret < 0)
> + goto i2c_error;
> +
> + ret = ssd1307fb_write_cmd(client, 0x00);
> + if (ret < 0)
> + goto i2c_error;
> +
> + ret = ssd1307fb_write_cmd(client, 0x10);
> + if (ret < 0)
> + goto i2c_error;
> +
> + for (j = 0; j < SSD1307FB_WIDTH; j++)
> + ssd1307fb_write_data(client, value);
> + }
> +
> + return 0;
> +
> +i2c_error:
> + dev_err(&client->dev, "Couldn't send i2c command: %d\n", ret);
> + return ret;
> +}
> +
> +static void ssd1307fb_update_display(struct ssd1307fb_par *par)
> +{
> + u8 *vmem = par->info->screen_base;
> + int i, j, k;
> +
> + /*
> + * 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 < (SSD1307FB_HEIGHT / 8); i++) {
> + ssd1307fb_write_cmd(par->client, SSD1307FB_START_PAGE_ADDRESS + (i + 1));
> + ssd1307fb_write_cmd(par->client, 0x00);
> + ssd1307fb_write_cmd(par->client, 0x10);
> +
> + for (j = 0; j < SSD1307FB_WIDTH; j++) {
> + u8 buf = 0;
> + for (k = 0; k < 8; k++) {
> + u32 page_length = SSD1307FB_WIDTH * i;
> + u32 index = page_length + (SSD1307FB_WIDTH * k + j) / 8;
> + u8 byte = *(vmem + index);
> + u8 bit = byte & (1 << (7 - (j % 8)));
> + bit = bit >> (7 - (j % 8));
> + buf |= bit << k;
> + }
> + ssd1307fb_write_data(par->client, buf);
> + }
> + }
> +
> + return;
> +}
> +
> +

Please remove unnecessary line.

> +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 p = *ppos;
> + void *dst;
> + int err = 0;
> +
> + dst = (void __force *) (info->screen_base + p);
> +
> + if (copy_from_user(dst, buf, count))
> + err = -EFAULT;
> +
> + if (!err)
> + *ppos += count;
> +
> + ssd1307fb_update_display(par);
> +
> + return (err) ? err : 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 __devinit ssd1307fb_probe(struct i2c_client *client, const struct i2c_device_id *id)
> +{
> + struct fb_info *info;
> + u32 vmem_size = SSD1307FB_WIDTH * SSD1307FB_HEIGHT / 8;
> + struct ssd1307fb_par *par;
> + u8 *vmem;
> + int ret;
> +
> + if (!client->dev.of_node) {
> + dev_err(&client->dev, "No device tree data found!\n");
> + ret = -EINVAL;
> + goto generic_error;
> + }

How about using returning -EINVAL without goto.
It is simpler.

if (!client->dev.of_node) {
dev_err(&client->dev, "No device tree data found!\n");
return -EINVAL;
}

> +
> + info = framebuffer_alloc(sizeof(struct ssd1307fb_par), &client->dev);
> + if (!info) {
> + ret = -ENOMEM;
> + goto generic_error;
> + }

Ditto.

> +
> + vmem = devm_kzalloc(&client->dev, vmem_size, GFP_KERNEL);
> + if (!vmem) {
> + dev_err(&client->dev, "Couldn't allocate graphical memory.\n");
> + ret = -ENOMEM;
> + goto generic_error;
> + }

Please fix this 'goto generic_error'. goto generic_error cannot call
framebuffer_release(). If framebuffer_alloc() is already called,
framebuffer_release() should be called when error happens.

> +
> + info->fbops = &ssd1307fb_ops;
> + info->fix = ssd1307fb_fix;
> + info->fbdefio = &ssd1307fb_defio;
> +
> + info->var = ssd1307fb_var;
> + 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);
> +
> + par = info->par;
> + par->info = info;
> + par->client = client;
> +
> + par->reset = of_get_named_gpio(client->dev.of_node,
> + "oled-reset-gpio", 0);
> + if (gpio_is_valid(par->reset)) {
> + int flags = GPIOF_OUT_INIT_HIGH;
> + if (of_get_property(client->dev.of_node,
> + "oled-reset-active-low", NULL))
> + flags = GPIOF_OUT_INIT_LOW;
> + ret = devm_gpio_request_one(&client->dev, par->reset,
> + flags, "oled-reset");
> + if (ret) {
> + dev_err(&client->dev,
> + "failed to request gpio %d: %d\n",
> + par->reset, ret);
> + goto reset_oled_error;
> + }
> + }
> +
> + par->pwm = pwm_get(&client->dev, NULL);
> + if (IS_ERR(par->pwm)) {
> + dev_err(&client->dev, "Could not get PWM from device tree!\n");
> + ret = PTR_ERR(par->pwm);
> + goto pwm_error;
> + }
> +
> + par->pwm_period = pwm_get_period(par->pwm);
> +
> + dev_dbg(&client->dev, "Using PWM%d with a %dns period.\n", par->pwm->pwm, par->pwm_period);
> +
> + ret = register_framebuffer(info);
> + if (ret) {
> + dev_err(&client->dev, "Couldn't register the framebuffer\n");
> + goto fbreg_error;
> + }
> +
> + i2c_set_clientdata(client, info);
> +
> + /* Reset the screen */
> + gpio_set_value(par->reset, 1);
> + udelay(4);
> + gpio_set_value(par->reset, 0);
> + udelay(4);
> +
> + /* Enable the PWM */
> + pwm_config(par->pwm, par->pwm_period / 2, par->pwm_period);
> + pwm_enable(par->pwm);
> +
> + /* Map column 127 of the OLED to segment 0 */
> + ret = ssd1307fb_write_cmd(client, SSD1307FB_SEG_REMAP_ON);
> + if (ret < 0) {
> + dev_err(&client->dev, "Couldn't remap the screen.\n");
> + goto remap_error;
> + }
> +
> + /* Turn on the display */
> + ret = ssd1307fb_write_cmd(client, SSD1307FB_DISPLAY_ON);
> + if (ret < 0) {
> + dev_err(&client->dev, "Couldn't turn the display on.\n");
> + goto remap_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;
> +
> +remap_error:
> + unregister_framebuffer(info);
> + pwm_disable(par->pwm);
> +fbreg_error:
> + pwm_put(par->pwm);
> +pwm_error:
> +reset_oled_error:
> + fb_deferred_io_cleanup(info);
> + framebuffer_release(info);
> +generic_error:
> + return ret;
> +}
> +
> +static int __devexit ssd1307fb_remove(struct i2c_client *client)
> +{
> + struct fb_info *info = i2c_get_clientdata(client);
> + struct ssd1307fb_par *par = info->par;

How about insert new line between variables and functions
to enhance the readability?

> + unregister_framebuffer(info);
> + pwm_disable(par->pwm);
> + pwm_put(par->pwm);
> + fb_deferred_io_cleanup(info);
> + framebuffer_release(info);
> +
> + return 0;
> +}
> +
> +static const struct i2c_device_id ssd1307fb_i2c_id[] = {
> + { "ssd1307fb", 0 },
> + { }
> +};
> +MODULE_DEVICE_TABLE(i2c, ssd1307fb_i2c_id);
> +
> +static const struct of_device_id ssd1307fb_of_match[] = {
> + { .compatible = "solomon,ssd1307fb-i2c" },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, ssd1307fb_of_match);
> +
> +static struct i2c_driver ssd1307fb_driver = {
> + .probe = ssd1307fb_probe,
> + .remove = __devexit_p(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 controler");
> +MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
> +MODULE_LICENSE("GPL");
> --
> 1.7.9.5
>
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