linux-next/drivers/video/metronomefb.c

/*
 * linux/drivers/video/metronomefb.c -- FB driver for Metronome controller
 *
 * Copyright (C) 2008, Jaya Kumar
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License. See the file COPYING in the main directory of this archive for
 * more details.
 *
 * Layout is based on skeletonfb.c by James Simmons and Geert Uytterhoeven.
 *
 * This work was made possible by help and equipment support from E-Ink
 * Corporation. http://support.eink.com/community
 *
 * This driver is written to be used with the Metronome display controller.
 * It was tested with an E-Ink 800x600 Vizplex EPD on a Gumstix Connex board
 * using the Lyre interface board.
 *
 * General notes:
 * - User must set metronomefb_enable=1 to enable it.
 * - See Documentation/fb/metronomefb.txt for how metronome works.
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/fb.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/list.h>
#include <linux/firmware.h>
#include <linux/dma-mapping.h>
#include <linux/uaccess.h>
#include <linux/irq.h>

#include <asm/arch/pxa-regs.h>
#include <asm/unaligned.h>

#define DEBUG 1
#ifdef DEBUG
#define DPRINTK(f, a...) printk(KERN_DEBUG "%s: " f, __func__ , ## a)
#else
#define DPRINTK(f, a...)
#endif


/* Display specific information */
#define DPY_W 832
#define DPY_H 622

struct metromem_desc {
	u32 mFDADR0;
	u32 mFSADR0;
	u32 mFIDR0;
	u32 mLDCMD0;
};

struct metromem_cmd {
	u16 opcode;
	u16 args[((64-2)/2)];
	u16 csum;
};

struct metronomefb_par {
	unsigned char *metromem;
	struct metromem_desc *metromem_desc;
	struct metromem_cmd *metromem_cmd;
	unsigned char *metromem_wfm;
	unsigned char *metromem_img;
	u16 *metromem_img_csum;
	u16 *csum_table;
	int metromemsize;
	dma_addr_t metromem_dma;
	dma_addr_t metromem_desc_dma;
	struct fb_info *info;
	wait_queue_head_t waitq;
	u8 frame_count;
};

/* frame differs from image. frame includes non-visible pixels */
struct epd_frame {
	int fw; /* frame width */
	int fh; /* frame height */
};

static struct epd_frame epd_frame_table[] = {
	{
	.fw = 832,
	.fh = 622
	},
};

static struct fb_fix_screeninfo metronomefb_fix __devinitdata = {
	.id =		"metronomefb",
	.type =		FB_TYPE_PACKED_PIXELS,
	.visual =	FB_VISUAL_STATIC_PSEUDOCOLOR,
	.xpanstep =	0,
	.ypanstep =	0,
	.ywrapstep =	0,
	.line_length =	DPY_W,
	.accel =	FB_ACCEL_NONE,
};

static struct fb_var_screeninfo metronomefb_var __devinitdata = {
	.xres		= DPY_W,
	.yres		= DPY_H,
	.xres_virtual	= DPY_W,
	.yres_virtual	= DPY_H,
	.bits_per_pixel	= 8,
	.grayscale	= 1,
	.nonstd		= 1,
	.red =		{ 4, 3, 0 },
	.green =	{ 0, 0, 0 },
	.blue =		{ 0, 0, 0 },
	.transp =	{ 0, 0, 0 },
};

static unsigned int metronomefb_enable;

struct waveform_hdr {
	u8 stuff[32];

	u8 wmta[3];
	u8 fvsn;

	u8 luts;
	u8 mc;
	u8 trc;
	u8 stuff3;

	u8 endb;
	u8 swtb;
	u8 stuff2a[2];

	u8 stuff2b[3];
	u8 wfm_cs;
} __attribute__ ((packed));

/* main metronomefb functions */
static u8 calc_cksum(int start, int end, u8 *mem)
{
	u8 tmp = 0;
	int i;

	for (i = start; i < end; i++)
		tmp += mem[i];

	return tmp;
}

static u16 calc_img_cksum(u16 *start, int length)
{
	u16 tmp = 0;

	while (length--)
		tmp += *start++;

	return tmp;
}

/* here we decode the incoming waveform file and populate metromem */
#define EXP_WFORM_SIZE 47001
static int load_waveform(u8 *mem, size_t size, u8 *metromem, int m, int t,
				u8 *frame_count)
{
	int tta;
	int wmta;
	int trn = 0;
	int i;
	unsigned char v;
	u8 cksum;
	int cksum_idx;
	int wfm_idx, owfm_idx;
	int mem_idx = 0;
	struct waveform_hdr *wfm_hdr;

	if (size != EXP_WFORM_SIZE) {
		printk(KERN_ERR "Error: unexpected size %d != %d\n", size,
					EXP_WFORM_SIZE);
		return -EINVAL;
	}

	wfm_hdr = (struct waveform_hdr *) mem;

	if (wfm_hdr->fvsn != 1) {
		printk(KERN_ERR "Error: bad fvsn %x\n", wfm_hdr->fvsn);
		return -EINVAL;
	}
	if (wfm_hdr->luts != 0) {
		printk(KERN_ERR "Error: bad luts %x\n", wfm_hdr->luts);
		return -EINVAL;
	}
	cksum = calc_cksum(32, 47, mem);
	if (cksum != wfm_hdr->wfm_cs) {
		printk(KERN_ERR "Error: bad cksum %x != %x\n", cksum,
					wfm_hdr->wfm_cs);
		return -EINVAL;
	}
	wfm_hdr->mc += 1;
	wfm_hdr->trc += 1;
	for (i = 0; i < 5; i++) {
		if (*(wfm_hdr->stuff2a + i) != 0) {
			printk(KERN_ERR "Error: unexpected value in padding\n");
			return -EINVAL;
		}
	}

	/* calculating trn. trn is something used to index into
	the waveform. presumably selecting the right one for the
	desired temperature. it works out the offset of the first
	v that exceeds the specified temperature */
	if ((sizeof(*wfm_hdr) + wfm_hdr->trc) > size)
		return -EINVAL;

	for (i = sizeof(*wfm_hdr); i <= sizeof(*wfm_hdr) + wfm_hdr->trc; i++) {
		if (mem[i] > t) {
			trn = i - sizeof(*wfm_hdr) - 1;
			break;
		}
	}

	/* check temperature range table checksum */
	cksum_idx = sizeof(*wfm_hdr) + wfm_hdr->trc + 1;
	if (cksum_idx > size)
		return -EINVAL;
	cksum = calc_cksum(sizeof(*wfm_hdr), cksum_idx, mem);
	if (cksum != mem[cksum_idx]) {
		printk(KERN_ERR "Error: bad temperature range table cksum"
				" %x != %x\n", cksum, mem[cksum_idx]);
		return -EINVAL;
	}

	/* check waveform mode table address checksum */
	wmta = le32_to_cpu(get_unaligned((__le32 *) wfm_hdr->wmta));
	wmta &= 0x00FFFFFF;
	cksum_idx = wmta + m*4 + 3;
	if (cksum_idx > size)
		return -EINVAL;
	cksum = calc_cksum(cksum_idx - 3, cksum_idx, mem);
	if (cksum != mem[cksum_idx]) {
		printk(KERN_ERR "Error: bad mode table address cksum"
				" %x != %x\n", cksum, mem[cksum_idx]);
		return -EINVAL;
	}

	/* check waveform temperature table address checksum */
	tta = le32_to_cpu(get_unaligned((int *) (mem + wmta + m*4)));
	tta &= 0x00FFFFFF;
	cksum_idx = tta + trn*4 + 3;
	if (cksum_idx > size)
		return -EINVAL;
	cksum = calc_cksum(cksum_idx - 3, cksum_idx, mem);
	if (cksum != mem[cksum_idx]) {
		printk(KERN_ERR "Error: bad temperature table address cksum"
			" %x != %x\n", cksum, mem[cksum_idx]);
		return -EINVAL;
	}

	/* here we do the real work of putting the waveform into the
	metromem buffer. this does runlength decoding of the waveform */
	wfm_idx = le32_to_cpu(get_unaligned((__le32 *) (mem + tta + trn*4)));
	wfm_idx &= 0x00FFFFFF;
	owfm_idx = wfm_idx;
	if (wfm_idx > size)
		return -EINVAL;
	while (wfm_idx < size) {
		unsigned char rl;
		v = mem[wfm_idx++];
		if (v == wfm_hdr->swtb) {
			while (((v = mem[wfm_idx++]) != wfm_hdr->swtb) &&
				wfm_idx < size)
				metromem[mem_idx++] = v;

			continue;
		}

		if (v == wfm_hdr->endb)
			break;

		rl = mem[wfm_idx++];
		for (i = 0; i <= rl; i++)
			metromem[mem_idx++] = v;
	}

	cksum_idx = wfm_idx;
	if (cksum_idx > size)
		return -EINVAL;
	cksum = calc_cksum(owfm_idx, cksum_idx, mem);
	if (cksum != mem[cksum_idx]) {
		printk(KERN_ERR "Error: bad waveform data cksum"
				" %x != %x\n", cksum, mem[cksum_idx]);
		return -EINVAL;
	}
	*frame_count = (mem_idx/64);

	return 0;
}

/* register offsets for gpio control */
#define LED_GPIO_PIN 51
#define STDBY_GPIO_PIN 48
#define RST_GPIO_PIN 49
#define RDY_GPIO_PIN 32
#define ERR_GPIO_PIN 17
#define PCBPWR_GPIO_PIN 16

#define AF_SEL_GPIO_N 0x3
#define GAFR0_U_OFFSET(pin) ((pin - 16) * 2)
#define GAFR1_L_OFFSET(pin) ((pin - 32) * 2)
#define GAFR1_U_OFFSET(pin) ((pin - 48) * 2)
#define GPDR1_OFFSET(pin) (pin - 32)
#define GPCR1_OFFSET(pin) (pin - 32)
#define GPSR1_OFFSET(pin) (pin - 32)
#define GPCR0_OFFSET(pin) (pin)
#define GPSR0_OFFSET(pin) (pin)

static void metronome_set_gpio_output(int pin, int val)
{
	u8 index;

	index = pin >> 4;

	switch (index) {
	case 1:
		if (val)
			GPSR0 |= (1 << GPSR0_OFFSET(pin));
		else
			GPCR0 |= (1 << GPCR0_OFFSET(pin));
		break;
	case 2:
		break;
	case 3:
		if (val)
			GPSR1 |= (1 << GPSR1_OFFSET(pin));
		else
			GPCR1 |= (1 << GPCR1_OFFSET(pin));
		break;
	default:
		printk(KERN_ERR "unimplemented\n");
	}
}

static void __devinit metronome_init_gpio_pin(int pin, int dir)
{
	u8 index;
	/* dir 0 is output, 1 is input
	- do 2 things here:
	- set gpio alternate function to standard gpio
	- set gpio direction to input or output  */

	index = pin >> 4;
	switch (index) {
	case 1:
		GAFR0_U &= ~(AF_SEL_GPIO_N << GAFR0_U_OFFSET(pin));

		if (dir)
			GPDR0 &= ~(1 << pin);
		else
			GPDR0 |= (1 << pin);
		break;
	case 2:
		GAFR1_L &= ~(AF_SEL_GPIO_N << GAFR1_L_OFFSET(pin));

		if (dir)
			GPDR1 &= ~(1 << GPDR1_OFFSET(pin));
		else
			GPDR1 |= (1 << GPDR1_OFFSET(pin));
		break;
	case 3:
		GAFR1_U &= ~(AF_SEL_GPIO_N << GAFR1_U_OFFSET(pin));

		if (dir)
			GPDR1 &= ~(1 << GPDR1_OFFSET(pin));
		else
			GPDR1 |= (1 << GPDR1_OFFSET(pin));
		break;
	default:
		printk(KERN_ERR "unimplemented\n");
	}
}

static void __devinit metronome_init_gpio_regs(void)
{
	metronome_init_gpio_pin(LED_GPIO_PIN, 0);
	metronome_set_gpio_output(LED_GPIO_PIN, 0);

	metronome_init_gpio_pin(STDBY_GPIO_PIN, 0);
	metronome_set_gpio_output(STDBY_GPIO_PIN, 0);

	metronome_init_gpio_pin(RST_GPIO_PIN, 0);
	metronome_set_gpio_output(RST_GPIO_PIN, 0);

	metronome_init_gpio_pin(RDY_GPIO_PIN, 1);

	metronome_init_gpio_pin(ERR_GPIO_PIN, 1);

	metronome_init_gpio_pin(PCBPWR_GPIO_PIN, 0);
	metronome_set_gpio_output(PCBPWR_GPIO_PIN, 0);
}

static void metronome_disable_lcd_controller(struct metronomefb_par *par)
{
	LCSR = 0xffffffff;	/* Clear LCD Status Register */
	LCCR0 |= LCCR0_DIS;	/* Disable LCD Controller */

	/* we reset and just wait for things to settle */
	msleep(200);
}

static void metronome_enable_lcd_controller(struct metronomefb_par *par)
{
	LCSR = 0xffffffff;
	FDADR0 = par->metromem_desc_dma;
	LCCR0 |= LCCR0_ENB;
}

static void __devinit metronome_init_lcdc_regs(struct metronomefb_par *par)
{
	/* here we do:
	- disable the lcd controller
	- setup lcd control registers
	- setup dma descriptor
	- reenable lcd controller
	*/

	/* disable the lcd controller */
	metronome_disable_lcd_controller(par);

	/* setup lcd control registers */
	LCCR0 = LCCR0_LDM | LCCR0_SFM | LCCR0_IUM | LCCR0_EFM | LCCR0_PAS
		| LCCR0_QDM | LCCR0_BM | LCCR0_OUM;

	LCCR1 = (epd_frame_table[0].fw/2 - 1) /* pixels per line */
		| (27 << 10) /* hsync pulse width - 1 */
		| (33 << 16) /* eol pixel count */
		| (33 << 24); /* bol pixel count */

	LCCR2 = (epd_frame_table[0].fh - 1) /* lines per panel */
		| (24 << 10) /* vsync pulse width - 1 */
		| (2 << 16) /* eof pixel count */
		| (0 << 24); /* bof pixel count */

	LCCR3 = 2 /* pixel clock divisor */
		| (24 << 8) /* AC Bias pin freq */
		| LCCR3_16BPP /* BPP */
		| LCCR3_PCP;  /* PCP falling edge */

	/* setup dma descriptor */
	par->metromem_desc->mFDADR0 = par->metromem_desc_dma;
	par->metromem_desc->mFSADR0 = par->metromem_dma;
	par->metromem_desc->mFIDR0 = 0;
	par->metromem_desc->mLDCMD0 = epd_frame_table[0].fw
					* epd_frame_table[0].fh;
	/* reenable lcd controller */
	metronome_enable_lcd_controller(par);
}

static int metronome_display_cmd(struct metronomefb_par *par)
{
	int i;
	u16 cs;
	u16 opcode;
	static u8 borderval;
	u8 *ptr;

	/* setup display command
	we can't immediately set the opcode since the controller
	will try parse the command before we've set it all up
	so we just set cs here and set the opcode at the end */

	ptr = par->metromem;

	if (par->metromem_cmd->opcode == 0xCC40)
		opcode = cs = 0xCC41;
	else
		opcode = cs = 0xCC40;

	/* set the args ( 2 bytes ) for display */
	i = 0;
	par->metromem_cmd->args[i] = 	1 << 3 /* border update */
					| ((borderval++ % 4) & 0x0F) << 4
					| (par->frame_count - 1) << 8;
	cs += par->metromem_cmd->args[i++];

	/* the rest are 0 */
	memset((u8 *) (par->metromem_cmd->args + i), 0, (32-i)*2);

	par->metromem_cmd->csum = cs;
	par->metromem_cmd->opcode = opcode; /* display cmd */

	i = wait_event_interruptible_timeout(par->waitq, (GPLR1 & 0x01), HZ);
	return i;
}

static int __devinit metronome_powerup_cmd(struct metronomefb_par *par)
{
	int i;
	u16 cs;

	/* setup power up command */
	par->metromem_cmd->opcode = 0x1234; /* pwr up pseudo cmd */
	cs = par->metromem_cmd->opcode;

	/* set pwr1,2,3 to 1024 */
	for (i = 0; i < 3; i++) {
		par->metromem_cmd->args[i] = 1024;
		cs += par->metromem_cmd->args[i];
	}

	/* the rest are 0 */
	memset((u8 *) (par->metromem_cmd->args + i), 0, (32-i)*2);

	par->metromem_cmd->csum = cs;

	msleep(1);
	metronome_set_gpio_output(RST_GPIO_PIN, 1);

	msleep(1);
	metronome_set_gpio_output(STDBY_GPIO_PIN, 1);

	i = wait_event_timeout(par->waitq, (GPLR1 & 0x01), HZ);
	return i;
}

static int __devinit metronome_config_cmd(struct metronomefb_par *par)
{
	int i;
	u16 cs;

	/* setup config command
	we can't immediately set the opcode since the controller
	will try parse the command before we've set it all up
	so we just set cs here and set the opcode at the end */

	cs = 0xCC10;

	/* set the 12 args ( 8 bytes ) for config. see spec for meanings */
	i = 0;
	par->metromem_cmd->args[i] = 	15 /* sdlew */
					| 2 << 8 /* sdosz */
					| 0 << 11 /* sdor */
					| 0 << 12 /* sdces */
					| 0 << 15; /* sdcer */
	cs += par->metromem_cmd->args[i++];

	par->metromem_cmd->args[i] = 	42 /* gdspl */
					| 1 << 8 /* gdr1 */
					| 1 << 9 /* sdshr */
					| 0 << 15; /* gdspp */
	cs += par->metromem_cmd->args[i++];

	par->metromem_cmd->args[i] = 	18 /* gdspw */
					| 0 << 15; /* dispc */
	cs += par->metromem_cmd->args[i++];

	par->metromem_cmd->args[i] = 	599 /* vdlc */
					| 0 << 11 /* dsi */
					| 0 << 12; /* dsic */
	cs += par->metromem_cmd->args[i++];

	/* the rest are 0 */
	memset((u8 *) (par->metromem_cmd->args + i), 0, (32-i)*2);

	par->metromem_cmd->csum = cs;
	par->metromem_cmd->opcode = 0xCC10; /* config cmd */

	i = wait_event_timeout(par->waitq, (GPLR1 & 0x01), HZ);
	return i;
}

static int __devinit metronome_init_cmd(struct metronomefb_par *par)
{
	int i;
	u16 cs;

	/* setup init command
	we can't immediately set the opcode since the controller
	will try parse the command before we've set it all up
	so we just set cs here and set the opcode at the end */

	cs = 0xCC20;

	/* set the args ( 2 bytes ) for init */
	i = 0;
	par->metromem_cmd->args[i] = 0;
	cs += par->metromem_cmd->args[i++];

	/* the rest are 0 */
	memset((u8 *) (par->metromem_cmd->args + i), 0, (32-i)*2);

	par->metromem_cmd->csum = cs;
	par->metromem_cmd->opcode = 0xCC20; /* init cmd */

	i = wait_event_timeout(par->waitq, (GPLR1 & 0x01), HZ);
	return i;
}

static int __devinit metronome_init_regs(struct metronomefb_par *par)
{
	int res;

	metronome_init_gpio_regs();
	metronome_init_lcdc_regs(par);

	res = metronome_powerup_cmd(par);
	if (res)
		return res;

	res = metronome_config_cmd(par);
	if (res)
		return res;

	res = metronome_init_cmd(par);
	if (res)
		return res;

	return res;
}

static void metronomefb_dpy_update(struct metronomefb_par *par)
{
	u16 cksum;
	unsigned char *buf = (unsigned char __force *)par->info->screen_base;

	/* copy from vm to metromem */
	memcpy(par->metromem_img, buf, DPY_W*DPY_H);

	cksum = calc_img_cksum((u16 *) par->metromem_img,
				(epd_frame_table[0].fw * DPY_H)/2);
	*((u16 *) (par->metromem_img) +
			(epd_frame_table[0].fw * DPY_H)/2) = cksum;
	metronome_display_cmd(par);
}

static u16 metronomefb_dpy_update_page(struct metronomefb_par *par, int index)
{
	int i;
	u16 csum = 0;
	u16 *buf = (u16 __force *) (par->info->screen_base + index);
	u16 *img = (u16 *) (par->metromem_img + index);

	/* swizzle from vm to metromem and recalc cksum at the same time*/
	for (i = 0; i < PAGE_SIZE/2; i++) {
		*(img + i) = (buf[i] << 5) & 0xE0E0;
		csum += *(img + i);
	}
	return csum;
}

/* this is called back from the deferred io workqueue */
static void metronomefb_dpy_deferred_io(struct fb_info *info,
				struct list_head *pagelist)
{
	u16 cksum;
	struct page *cur;
	struct fb_deferred_io *fbdefio = info->fbdefio;
	struct metronomefb_par *par = info->par;

	/* walk the written page list and swizzle the data */
	list_for_each_entry(cur, &fbdefio->pagelist, lru) {
		cksum = metronomefb_dpy_update_page(par,
					(cur->index << PAGE_SHIFT));
		par->metromem_img_csum -= par->csum_table[cur->index];
		par->csum_table[cur->index] = cksum;
		par->metromem_img_csum += cksum;
	}

	metronome_display_cmd(par);
}

static void metronomefb_fillrect(struct fb_info *info,
				   const struct fb_fillrect *rect)
{
	struct metronomefb_par *par = info->par;

	cfb_fillrect(info, rect);
	metronomefb_dpy_update(par);
}

static void metronomefb_copyarea(struct fb_info *info,
				   const struct fb_copyarea *area)
{
	struct metronomefb_par *par = info->par;

	cfb_copyarea(info, area);
	metronomefb_dpy_update(par);
}

static void metronomefb_imageblit(struct fb_info *info,
				const struct fb_image *image)
{
	struct metronomefb_par *par = info->par;

	cfb_imageblit(info, image);
	metronomefb_dpy_update(par);
}

/*
 * this is the slow path from userspace. they can seek and write to
 * the fb. it is based on fb_sys_write
 */
static ssize_t metronomefb_write(struct fb_info *info, const char __user *buf,
				size_t count, loff_t *ppos)
{
	struct metronomefb_par *par = info->par;
	unsigned long p = *ppos;
	void *dst;
	int err = 0;
	unsigned long total_size;

	if (info->state != FBINFO_STATE_RUNNING)
		return -EPERM;

	total_size = info->fix.smem_len;

	if (p > total_size)
		return -EFBIG;

	if (count > total_size) {
		err = -EFBIG;
		count = total_size;
	}

	if (count + p > total_size) {
		if (!err)
			err = -ENOSPC;

		count = total_size - p;
	}

	dst = (void __force *) (info->screen_base + p);

	if (copy_from_user(dst, buf, count))
		err = -EFAULT;

	if  (!err)
		*ppos += count;

	metronomefb_dpy_update(par);

	return (err) ? err : count;
}

static struct fb_ops metronomefb_ops = {
	.owner		= THIS_MODULE,
	.fb_write	= metronomefb_write,
	.fb_fillrect	= metronomefb_fillrect,
	.fb_copyarea	= metronomefb_copyarea,
	.fb_imageblit	= metronomefb_imageblit,
};

static struct fb_deferred_io metronomefb_defio = {
	.delay		= HZ,
	.deferred_io	= metronomefb_dpy_deferred_io,
};

static irqreturn_t metronome_handle_irq(int irq, void *dev_id)
{
	struct fb_info *info = dev_id;
	struct metronomefb_par *par = info->par;

	wake_up_interruptible(&par->waitq);
	return IRQ_HANDLED;
}

static int __devinit metronomefb_probe(struct platform_device *dev)
{
	struct fb_info *info;
	int retval = -ENOMEM;
	int videomemorysize;
	unsigned char *videomemory;
	struct metronomefb_par *par;
	const struct firmware *fw_entry;
	int cmd_size, wfm_size, img_size, padding_size, totalsize;
	int i;

	/* we have two blocks of memory.
	info->screen_base which is vm, and is the fb used by apps.
	par->metromem which is physically contiguous memory and
	contains the display controller commands, waveform,
	processed image data and padding. this is the data pulled
	by the pxa255's LCD controller and pushed to Metronome */

	videomemorysize = (DPY_W*DPY_H);
	videomemory = vmalloc(videomemorysize);
	if (!videomemory)
		return retval;

	memset(videomemory, 0, videomemorysize);

	info = framebuffer_alloc(sizeof(struct metronomefb_par), &dev->dev);
	if (!info)
		goto err_vfree;

	info->screen_base = (char __iomem *) videomemory;
	info->fbops = &metronomefb_ops;

	info->var = metronomefb_var;
	info->fix = metronomefb_fix;
	info->fix.smem_len = videomemorysize;
	par = info->par;
	par->info = info;
	init_waitqueue_head(&par->waitq);

	/* this table caches per page csum values. */
	par->csum_table = vmalloc(videomemorysize/PAGE_SIZE);
	if (!par->csum_table)
		goto err_csum_table;

	/* the metromem buffer is divided as follows:
	command | CRC | padding
	16kb waveform data | CRC | padding
	image data | CRC
	and an extra 256 bytes for dma descriptors
	eg: IW=832 IH=622 WS=128
	*/

	cmd_size = 1 * epd_frame_table[0].fw;
	wfm_size = ((16*1024 + 2 + epd_frame_table[0].fw - 1)
			/ epd_frame_table[0].fw) * epd_frame_table[0].fw;
	img_size = epd_frame_table[0].fh * epd_frame_table[0].fw;
	padding_size = 4 * epd_frame_table[0].fw;
	totalsize = cmd_size + wfm_size + img_size + padding_size;
	par->metromemsize = PAGE_ALIGN(totalsize + 256);
	DPRINTK("desired memory size = %d\n", par->metromemsize);
	dev->dev.coherent_dma_mask = 0xffffffffull;
	par->metromem = dma_alloc_writecombine(&dev->dev, par->metromemsize,
						&par->metromem_dma, GFP_KERNEL);
	if (!par->metromem) {
		printk(KERN_ERR
			"metronomefb: unable to allocate dma buffer\n");
		goto err_vfree;
	}

	info->fix.smem_start = par->metromem_dma;
	par->metromem_cmd = (struct metromem_cmd *) par->metromem;
	par->metromem_wfm = par->metromem + cmd_size;
	par->metromem_img = par->metromem + cmd_size + wfm_size;
	par->metromem_img_csum = (u16 *) (par->metromem_img +
					(epd_frame_table[0].fw * DPY_H));
	DPRINTK("img offset=0x%x\n", cmd_size + wfm_size);
	par->metromem_desc = (struct metromem_desc *) (par->metromem + cmd_size
					+ wfm_size + img_size + padding_size);
	par->metromem_desc_dma = par->metromem_dma + cmd_size + wfm_size
				 + img_size + padding_size;

	/* load the waveform in. assume mode 3, temp 31 for now */
	/* 	a) request the waveform file from userspace
		b) process waveform and decode into metromem */

	retval = request_firmware(&fw_entry, "waveform.wbf", &dev->dev);
	if (retval < 0) {
		printk(KERN_ERR "metronomefb: couldn't get waveform\n");
		goto err_dma_free;
	}

	retval = load_waveform((u8 *) fw_entry->data, fw_entry->size,
				par->metromem_wfm, 3, 31, &par->frame_count);
	if (retval < 0) {
		printk(KERN_ERR "metronomefb: couldn't process waveform\n");
		goto err_ld_wfm;
	}
	release_firmware(fw_entry);

	retval = request_irq(IRQ_GPIO(RDY_GPIO_PIN), metronome_handle_irq,
				IRQF_DISABLED, "Metronome", info);
	if (retval) {
		dev_err(&dev->dev, "request_irq failed: %d\n", retval);
		goto err_ld_wfm;
	}
	set_irq_type(IRQ_GPIO(RDY_GPIO_PIN), IRQT_FALLING);

	retval = metronome_init_regs(par);
	if (retval < 0)
		goto err_free_irq;

	info->flags = FBINFO_FLAG_DEFAULT;

	info->fbdefio = &metronomefb_defio;
	fb_deferred_io_init(info);

	retval = fb_alloc_cmap(&info->cmap, 8, 0);
	if (retval < 0) {
		printk(KERN_ERR "Failed to allocate colormap\n");
		goto err_fb_rel;
	}

	/* set cmap */
	for (i = 0; i < 8; i++)
		info->cmap.red[i] = (((2*i)+1)*(0xFFFF))/16;
	memcpy(info->cmap.green, info->cmap.red, sizeof(u16)*8);
	memcpy(info->cmap.blue, info->cmap.red, sizeof(u16)*8);

	retval = register_framebuffer(info);
	if (retval < 0)
		goto err_cmap;

	platform_set_drvdata(dev, info);

	printk(KERN_INFO
		"fb%d: Metronome frame buffer device, using %dK of video"
		" memory\n", info->node, videomemorysize >> 10);

	return 0;

err_cmap:
	fb_dealloc_cmap(&info->cmap);
err_fb_rel:
	framebuffer_release(info);
err_free_irq:
	free_irq(IRQ_GPIO(RDY_GPIO_PIN), info);
err_ld_wfm:
	release_firmware(fw_entry);
err_dma_free:
	dma_free_writecombine(&dev->dev, par->metromemsize, par->metromem,
				par->metromem_dma);
err_csum_table:
	vfree(par->csum_table);
err_vfree:
	vfree(videomemory);
	return retval;
}

static int __devexit metronomefb_remove(struct platform_device *dev)
{
	struct fb_info *info = platform_get_drvdata(dev);

	if (info) {
		struct metronomefb_par *par = info->par;
		fb_deferred_io_cleanup(info);
		dma_free_writecombine(&dev->dev, par->metromemsize,
					par->metromem, par->metromem_dma);
		fb_dealloc_cmap(&info->cmap);
		vfree(par->csum_table);
		unregister_framebuffer(info);
		vfree((void __force *)info->screen_base);
		free_irq(IRQ_GPIO(RDY_GPIO_PIN), info);
		framebuffer_release(info);
	}
	return 0;
}

static struct platform_driver metronomefb_driver = {
	.probe	= metronomefb_probe,
	.remove = metronomefb_remove,
	.driver	= {
		.name	= "metronomefb",
	},
};

static struct platform_device *metronomefb_device;

static int __init metronomefb_init(void)
{
	int ret;

	if (!metronomefb_enable) {
		printk(KERN_ERR
			"Use metronomefb_enable to enable the device\n");
		return -ENXIO;
	}

	ret = platform_driver_register(&metronomefb_driver);
	if (!ret) {
		metronomefb_device = platform_device_alloc("metronomefb", 0);
		if (metronomefb_device)
			ret = platform_device_add(metronomefb_device);
		else
			ret = -ENOMEM;

		if (ret) {
			platform_device_put(metronomefb_device);
			platform_driver_unregister(&metronomefb_driver);
		}
	}
	return ret;

}

static void __exit metronomefb_exit(void)
{
	platform_device_unregister(metronomefb_device);
	platform_driver_unregister(&metronomefb_driver);
}

module_param(metronomefb_enable, uint, 0);
MODULE_PARM_DESC(metronomefb_enable, "Enable communication with Metronome");

module_init(metronomefb_init);
module_exit(metronomefb_exit);

MODULE_DESCRIPTION("fbdev driver for Metronome controller");
MODULE_AUTHOR("Jaya Kumar");
MODULE_LICENSE("GPL");