/*
 * 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 = 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");