drivers/video: add support for the Solomon SSD1307 OLED Controller

Add 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.

[[e-mail]: checkpatch fixes]
Signed-off-by: Maxime Ripard <[e-mail]>
Cc: Brian Lilly <[e-mail]>
Cc: Greg KH <[e-mail]>
Cc: Florian Tobias Schandinat <[e-mail]>
Cc: Thomas Petazzoni <[e-mail]>
Cc: Tomi Valkeinen <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Tomi Valkeinen <[e-mail]>

Documentation/devicetree/bindings/video/ssd1307fb.txt

···
+* 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]
+  - reset-gpios: Should contain the GPIO used to reset the OLED display
+
+Optional properties:
+  - reset-active-low: Is the reset gpio is active on physical low?
+
+[0]: Documentation/devicetree/bindings/pwm/pwm.txt
+
+Examples:
+ssd1307: oled@3c {
+        compatible = "solomon,ssd1307fb-i2c";
+        reg = <0x3c>;
+        pwms = <&pwm 4 3000>;
+        reset-gpios = <&gpio2 7>;
+        reset-active-low;
+};

drivers/video/Kconfig

···
 	  Up to 4 memory channels can be configured, allowing 4 RGB or
 	  2 YCbCr framebuffers to be configured.
 
+config FB_SSD1307
+	tristate "Solomon SSD1307 framebuffer support"
+	depends on FB && I2C
+	depends on OF
+	depends on GENERIC_GPIO
+	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

drivers/video/Makefile

···
 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

drivers/video/ssd1307fb.c

···
+/*
+ * 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");
+		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);
+	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 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);
+		}
+	}
+}
+
+
+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 __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");
+		return -EINVAL;
+	}
+
+	info = framebuffer_alloc(sizeof(struct ssd1307fb_par), &client->dev);
+	if (!info) {
+		dev_err(&client->dev, "Couldn't allocate framebuffer.\n");
+		return -ENOMEM;
+	}
+
+	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->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,
+					 "reset-gpios", 0);
+	if (!gpio_is_valid(par->reset)) {
+		ret = -EINVAL;
+		goto reset_oled_error;
+	}
+
+	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;
+	}
+
+	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, 0);
+	udelay(4);
+	gpio_set_value(par->reset, 1);
+	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);
+fb_alloc_error:
+	framebuffer_release(info);
+	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;
+
+	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 <[e-mail]>");
+MODULE_LICENSE("GPL");