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/*
 * SuperH IrDA Driver
 *
 * Copyright (C) 2009 Renesas Solutions Corp.
 * Kuninori Morimoto <morimoto.kuninori@renesas.com>
 *
 * Based on bfin_sir.c
 * Copyright 2006-2009 Analog Devices Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/io.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <net/irda/wrapper.h>
#include <net/irda/irda_device.h>
#include <asm/clock.h>

#define DRIVER_NAME "sh_sir"

#define RX_PHASE	(1 << 0)
#define TX_PHASE	(1 << 1)
#define TX_COMP_PHASE	(1 << 2) /* tx complete */
#define NONE_PHASE	(1 << 31)

#define IRIF_RINTCLR	0x0016 /* DMA rx interrupt source clear */
#define IRIF_TINTCLR	0x0018 /* DMA tx interrupt source clear */
#define IRIF_SIR0	0x0020 /* IrDA-SIR10 control */
#define IRIF_SIR1	0x0022 /* IrDA-SIR10 baudrate error correction */
#define IRIF_SIR2	0x0024 /* IrDA-SIR10 baudrate count */
#define IRIF_SIR3	0x0026 /* IrDA-SIR10 status */
#define IRIF_SIR_FRM	0x0028 /* Hardware frame processing set */
#define IRIF_SIR_EOF	0x002A /* EOF value */
#define IRIF_SIR_FLG	0x002C /* Flag clear */
#define IRIF_UART_STS2	0x002E /* UART status 2 */
#define IRIF_UART0	0x0030 /* UART control */
#define IRIF_UART1	0x0032 /* UART status */
#define IRIF_UART2	0x0034 /* UART mode */
#define IRIF_UART3	0x0036 /* UART transmit data */
#define IRIF_UART4	0x0038 /* UART receive data */
#define IRIF_UART5	0x003A /* UART interrupt mask */
#define IRIF_UART6	0x003C /* UART baud rate error correction */
#define IRIF_UART7	0x003E /* UART baud rate count set */
#define IRIF_CRC0	0x0040 /* CRC engine control */
#define IRIF_CRC1	0x0042 /* CRC engine input data */
#define IRIF_CRC2	0x0044 /* CRC engine calculation */
#define IRIF_CRC3	0x0046 /* CRC engine output data 1 */
#define IRIF_CRC4	0x0048 /* CRC engine output data 2 */

/* IRIF_SIR0 */
#define IRTPW		(1 << 1) /* transmit pulse width select */
#define IRERRC		(1 << 0) /* Clear receive pulse width error */

/* IRIF_SIR3 */
#define IRERR		(1 << 0) /* received pulse width Error */

/* IRIF_SIR_FRM */
#define EOFD		(1 << 9) /* EOF detection flag */
#define FRER		(1 << 8) /* Frame Error bit */
#define FRP		(1 << 0) /* Frame processing set */

/* IRIF_UART_STS2 */
#define IRSME		(1 << 6) /* Receive Sum     Error flag */
#define IROVE		(1 << 5) /* Receive Overrun Error flag */
#define IRFRE		(1 << 4) /* Receive Framing Error flag */
#define IRPRE		(1 << 3) /* Receive Parity  Error flag */

/* IRIF_UART0_*/
#define TBEC		(1 << 2) /* Transmit Data Clear */
#define RIE		(1 << 1) /* Receive Enable */
#define TIE		(1 << 0) /* Transmit Enable */

/* IRIF_UART1 */
#define URSME		(1 << 6) /* Receive Sum Error Flag */
#define UROVE		(1 << 5) /* Receive Overrun Error Flag */
#define URFRE		(1 << 4) /* Receive Framing Error Flag */
#define URPRE		(1 << 3) /* Receive Parity Error Flag */
#define RBF		(1 << 2) /* Receive Buffer Full Flag */
#define TSBE		(1 << 1) /* Transmit Shift Buffer Empty Flag */
#define TBE		(1 << 0) /* Transmit Buffer Empty flag */
#define TBCOMP		(TSBE | TBE)

/* IRIF_UART5 */
#define RSEIM		(1 << 6) /* Receive Sum Error Flag IRQ Mask */
#define RBFIM		(1 << 2) /* Receive Buffer Full Flag IRQ Mask */
#define TSBEIM		(1 << 1) /* Transmit Shift Buffer Empty Flag IRQ Mask */
#define TBEIM		(1 << 0) /* Transmit Buffer Empty Flag IRQ Mask */
#define RX_MASK		(RSEIM  | RBFIM)

/* IRIF_CRC0 */
#define CRC_RST		(1 << 15) /* CRC Engine Reset */
#define CRC_CT_MASK	0x0FFF

/************************************************************************


			structure


************************************************************************/
struct sh_sir_self {
	void __iomem		*membase;
	unsigned int		 irq;
	struct clk		*clk;

	struct net_device	*ndev;

	struct irlap_cb		*irlap;
	struct qos_info		qos;

	iobuff_t		tx_buff;
	iobuff_t		rx_buff;
};

/************************************************************************


			common function


************************************************************************/
static void sh_sir_write(struct sh_sir_self *self, u32 offset, u16 data)
{
	iowrite16(data, self->membase + offset);
}

static u16 sh_sir_read(struct sh_sir_self *self, u32 offset)
{
	return ioread16(self->membase + offset);
}

static void sh_sir_update_bits(struct sh_sir_self *self, u32 offset,
			       u16 mask, u16 data)
{
	u16 old, new;

	old = sh_sir_read(self, offset);
	new = (old & ~mask) | data;
	if (old != new)
		sh_sir_write(self, offset, new);
}

/************************************************************************


			CRC function


************************************************************************/
static void sh_sir_crc_reset(struct sh_sir_self *self)
{
	sh_sir_write(self, IRIF_CRC0, CRC_RST);
}

static void sh_sir_crc_add(struct sh_sir_self *self, u8 data)
{
	sh_sir_write(self, IRIF_CRC1, (u16)data);
}

static u16 sh_sir_crc_cnt(struct sh_sir_self *self)
{
	return CRC_CT_MASK & sh_sir_read(self, IRIF_CRC0);
}

static u16 sh_sir_crc_out(struct sh_sir_self *self)
{
	return sh_sir_read(self, IRIF_CRC4);
}

static int sh_sir_crc_init(struct sh_sir_self *self)
{
	struct device *dev = &self->ndev->dev;
	int ret = -EIO;
	u16 val;

	sh_sir_crc_reset(self);

	sh_sir_crc_add(self, 0xCC);
	sh_sir_crc_add(self, 0xF5);
	sh_sir_crc_add(self, 0xF1);
	sh_sir_crc_add(self, 0xA7);

	val = sh_sir_crc_cnt(self);
	if (4 != val) {
		dev_err(dev, "CRC count error %x\n", val);
		goto crc_init_out;
	}

	val = sh_sir_crc_out(self);
	if (0x51DF != val) {
		dev_err(dev, "CRC result error%x\n", val);
		goto crc_init_out;
	}

	ret = 0;

crc_init_out:

	sh_sir_crc_reset(self);
	return ret;
}

/************************************************************************


			baud rate functions


************************************************************************/
#define SCLK_BASE 1843200 /* 1.8432MHz */

static u32 sh_sir_find_sclk(struct clk *irda_clk)
{
	struct cpufreq_frequency_table *freq_table = irda_clk->freq_table;
	struct cpufreq_frequency_table *pos;
	struct clk *pclk = clk_get(NULL, "peripheral_clk");
	u32 limit, min = 0xffffffff, tmp;
	int index = 0;

	limit = clk_get_rate(pclk);
	clk_put(pclk);

	/* IrDA can not set over peripheral_clk */
	cpufreq_for_each_valid_entry(pos, freq_table) {
		u32 freq = pos->frequency;

		/* IrDA should not over peripheral_clk */
		if (freq > limit)
			continue;

		tmp = freq % SCLK_BASE;
		if (tmp < min) {
			min = tmp;
			index = pos - freq_table;
		}
	}

	return freq_table[index].frequency;
}

#define ERR_ROUNDING(a) ((a + 5000) / 10000)
static int sh_sir_set_baudrate(struct sh_sir_self *self, u32 baudrate)
{
	struct clk *clk;
	struct device *dev = &self->ndev->dev;
	u32 rate;
	u16 uabca, uabc;
	u16 irbca, irbc;
	u32 min, rerr, tmp;
	int i;

	/* Baud Rate Error Correction x 10000 */
	u32 rate_err_array[] = {
		   0,  625, 1250, 1875,
		2500, 3125, 3750, 4375,
		5000, 5625, 6250, 6875,
		7500, 8125, 8750, 9375,
	};

	/*
	 * FIXME
	 *
	 * it support 9600 only now
	 */
	switch (baudrate) {
	case 9600:
		break;
	default:
		dev_err(dev, "un-supported baudrate %d\n", baudrate);
		return -EIO;
	}

	clk = clk_get(NULL, "irda_clk");
	if (IS_ERR(clk)) {
		dev_err(dev, "can not get irda_clk\n");
		return -EIO;
	}

	clk_set_rate(clk, sh_sir_find_sclk(clk));
	rate = clk_get_rate(clk);
	clk_put(clk);

	dev_dbg(dev, "selected sclk = %d\n", rate);

	/*
	 * CALCULATION
	 *
	 * 1843200 = system rate / (irbca + (irbc + 1))
	 */

	irbc = rate / SCLK_BASE;

	tmp = rate - (SCLK_BASE * irbc);
	tmp *= 10000;

	rerr = tmp / SCLK_BASE;

	min = 0xffffffff;
	irbca = 0;
	for (i = 0; i < ARRAY_SIZE(rate_err_array); i++) {
		tmp = abs(rate_err_array[i] - rerr);
		if (min > tmp) {
			min = tmp;
			irbca = i;
		}
	}

	tmp = rate / (irbc + ERR_ROUNDING(rate_err_array[irbca]));
	if ((SCLK_BASE / 100) < abs(tmp - SCLK_BASE))
		dev_warn(dev, "IrDA freq error margin over %d\n", tmp);

	dev_dbg(dev, "target = %d, result = %d, infrared = %d.%d\n",
	       SCLK_BASE, tmp, irbc, rate_err_array[irbca]);

	irbca = (irbca & 0xF) << 4;
	irbc  = (irbc - 1) & 0xF;

	if (!irbc) {
		dev_err(dev, "sh_sir can not set 0 in IRIF_SIR2\n");
		return -EIO;
	}

	sh_sir_write(self, IRIF_SIR0, IRTPW | IRERRC);
	sh_sir_write(self, IRIF_SIR1, irbca);
	sh_sir_write(self, IRIF_SIR2, irbc);

	/*
	 * CALCULATION
	 *
	 * BaudRate[bps] = system rate / (uabca + (uabc + 1) x 16)
	 */

	uabc = rate / baudrate;
	uabc = (uabc / 16) - 1;
	uabc = (uabc + 1) * 16;

	tmp = rate - (uabc * baudrate);
	tmp *= 10000;

	rerr = tmp / baudrate;

	min = 0xffffffff;
	uabca = 0;
	for (i = 0; i < ARRAY_SIZE(rate_err_array); i++) {
		tmp = abs(rate_err_array[i] - rerr);
		if (min > tmp) {
			min = tmp;
			uabca = i;
		}
	}

	tmp = rate / (uabc + ERR_ROUNDING(rate_err_array[uabca]));
	if ((baudrate / 100) < abs(tmp - baudrate))
		dev_warn(dev, "UART freq error margin over %d\n", tmp);

	dev_dbg(dev, "target = %d, result = %d, uart = %d.%d\n",
	       baudrate, tmp,
	       uabc, rate_err_array[uabca]);

	uabca = (uabca & 0xF) << 4;
	uabc  = (uabc / 16) - 1;

	sh_sir_write(self, IRIF_UART6, uabca);
	sh_sir_write(self, IRIF_UART7, uabc);

	return 0;
}

/************************************************************************


			iobuf function


************************************************************************/
static int __sh_sir_init_iobuf(iobuff_t *io, int size)
{
	io->head = kmalloc(size, GFP_KERNEL);
	if (!io->head)
		return -ENOMEM;

	io->truesize	= size;
	io->in_frame	= FALSE;
	io->state	= OUTSIDE_FRAME;
	io->data	= io->head;

	return 0;
}

static void sh_sir_remove_iobuf(struct sh_sir_self *self)
{
	kfree(self->rx_buff.head);
	kfree(self->tx_buff.head);

	self->rx_buff.head = NULL;
	self->tx_buff.head = NULL;
}

static int sh_sir_init_iobuf(struct sh_sir_self *self, int rxsize, int txsize)
{
	int err = -ENOMEM;

	if (self->rx_buff.head ||
	    self->tx_buff.head) {
		dev_err(&self->ndev->dev, "iobuff has already existed.");
		return err;
	}

	err = __sh_sir_init_iobuf(&self->rx_buff, rxsize);
	if (err)
		goto iobuf_err;

	err = __sh_sir_init_iobuf(&self->tx_buff, txsize);

iobuf_err:
	if (err)
		sh_sir_remove_iobuf(self);

	return err;
}

/************************************************************************


			status function


************************************************************************/
static void sh_sir_clear_all_err(struct sh_sir_self *self)
{
	/* Clear error flag for receive pulse width */
	sh_sir_update_bits(self, IRIF_SIR0, IRERRC, IRERRC);

	/* Clear frame / EOF error flag */
	sh_sir_write(self, IRIF_SIR_FLG, 0xffff);

	/* Clear all status error */
	sh_sir_write(self, IRIF_UART_STS2, 0);
}

static void sh_sir_set_phase(struct sh_sir_self *self, int phase)
{
	u16 uart5 = 0;
	u16 uart0 = 0;

	switch (phase) {
	case TX_PHASE:
		uart5 = TBEIM;
		uart0 = TBEC | TIE;
		break;
	case TX_COMP_PHASE:
		uart5 = TSBEIM;
		uart0 = TIE;
		break;
	case RX_PHASE:
		uart5 = RX_MASK;
		uart0 = RIE;
		break;
	default:
		break;
	}

	sh_sir_write(self, IRIF_UART5, uart5);
	sh_sir_write(self, IRIF_UART0, uart0);
}

static int sh_sir_is_which_phase(struct sh_sir_self *self)
{
	u16 val = sh_sir_read(self, IRIF_UART5);

	if (val & TBEIM)
		return TX_PHASE;

	if (val & TSBEIM)
		return TX_COMP_PHASE;

	if (val & RX_MASK)
		return RX_PHASE;

	return NONE_PHASE;
}

static void sh_sir_tx(struct sh_sir_self *self, int phase)
{
	switch (phase) {
	case TX_PHASE:
		if (0 >= self->tx_buff.len) {
			sh_sir_set_phase(self, TX_COMP_PHASE);
		} else {
			sh_sir_write(self, IRIF_UART3, self->tx_buff.data[0]);
			self->tx_buff.len--;
			self->tx_buff.data++;
		}
		break;
	case TX_COMP_PHASE:
		sh_sir_set_phase(self, RX_PHASE);
		netif_wake_queue(self->ndev);
		break;
	default:
		dev_err(&self->ndev->dev, "should not happen\n");
		break;
	}
}

static int sh_sir_read_data(struct sh_sir_self *self)
{
	u16 val = 0;
	int timeout = 1024;

	while (timeout--) {
		val = sh_sir_read(self, IRIF_UART1);

		/* data get */
		if (val & RBF) {
			if (val & (URSME | UROVE | URFRE | URPRE))
				break;

			return (int)sh_sir_read(self, IRIF_UART4);
		}

		udelay(1);
	}

	dev_err(&self->ndev->dev, "UART1 %04x : STATUS %04x\n",
		val, sh_sir_read(self, IRIF_UART_STS2));

	/* read data register for clear error */
	sh_sir_read(self, IRIF_UART4);

	return -1;
}

static void sh_sir_rx(struct sh_sir_self *self)
{
	int timeout = 1024;
	int data;

	while (timeout--) {
		data = sh_sir_read_data(self);
		if (data < 0)
			break;

		async_unwrap_char(self->ndev, &self->ndev->stats,
				  &self->rx_buff, (u8)data);

		if (EOFD & sh_sir_read(self, IRIF_SIR_FRM))
			continue;

		break;
	}
}

static irqreturn_t sh_sir_irq(int irq, void *dev_id)
{
	struct sh_sir_self *self = dev_id;
	struct device *dev = &self->ndev->dev;
	int phase = sh_sir_is_which_phase(self);

	switch (phase) {
	case TX_COMP_PHASE:
	case TX_PHASE:
		sh_sir_tx(self, phase);
		break;
	case RX_PHASE:
		if (sh_sir_read(self, IRIF_SIR3))
			dev_err(dev, "rcv pulse width error occurred\n");

		sh_sir_rx(self);
		sh_sir_clear_all_err(self);
		break;
	default:
		dev_err(dev, "unknown interrupt\n");
	}

	 return IRQ_HANDLED;
}

/************************************************************************


			net_device_ops function


************************************************************************/
static int sh_sir_hard_xmit(struct sk_buff *skb, struct net_device *ndev)
{
	struct sh_sir_self *self = netdev_priv(ndev);
	int speed = irda_get_next_speed(skb);

	if ((0 < speed) &&
	    (9600 != speed)) {
		dev_err(&ndev->dev, "support 9600 only (%d)\n", speed);
		return -EIO;
	}

	netif_stop_queue(ndev);

	self->tx_buff.data = self->tx_buff.head;
	self->tx_buff.len = 0;
	if (skb->len)
		self->tx_buff.len = async_wrap_skb(skb, self->tx_buff.data,
						   self->tx_buff.truesize);

	sh_sir_set_phase(self, TX_PHASE);
	dev_kfree_skb(skb);

	return 0;
}

static int sh_sir_ioctl(struct net_device *ndev, struct ifreq *ifreq, int cmd)
{
	/*
	 * FIXME
	 *
	 * This function is needed for irda framework.
	 * But nothing to do now
	 */
	return 0;
}

static struct net_device_stats *sh_sir_stats(struct net_device *ndev)
{
	struct sh_sir_self *self = netdev_priv(ndev);

	return &self->ndev->stats;
}

static int sh_sir_open(struct net_device *ndev)
{
	struct sh_sir_self *self = netdev_priv(ndev);
	int err;

	clk_enable(self->clk);
	err = sh_sir_crc_init(self);
	if (err)
		goto open_err;

	sh_sir_set_baudrate(self, 9600);

	self->irlap = irlap_open(ndev, &self->qos, DRIVER_NAME);
	if (!self->irlap) {
		err = -ENODEV;
		goto open_err;
	}

	/*
	 * Now enable the interrupt then start the queue
	 */
	sh_sir_update_bits(self, IRIF_SIR_FRM, FRP, FRP);
	sh_sir_read(self, IRIF_UART1); /* flag clear */
	sh_sir_read(self, IRIF_UART4); /* flag clear */
	sh_sir_set_phase(self, RX_PHASE);

	netif_start_queue(ndev);

	dev_info(&self->ndev->dev, "opened\n");

	return 0;

open_err:
	clk_disable(self->clk);

	return err;
}

static int sh_sir_stop(struct net_device *ndev)
{
	struct sh_sir_self *self = netdev_priv(ndev);

	/* Stop IrLAP */
	if (self->irlap) {
		irlap_close(self->irlap);
		self->irlap = NULL;
	}

	netif_stop_queue(ndev);

	dev_info(&ndev->dev, "stopped\n");

	return 0;
}

static const struct net_device_ops sh_sir_ndo = {
	.ndo_open		= sh_sir_open,
	.ndo_stop		= sh_sir_stop,
	.ndo_start_xmit		= sh_sir_hard_xmit,
	.ndo_do_ioctl		= sh_sir_ioctl,
	.ndo_get_stats		= sh_sir_stats,
};

/************************************************************************


			platform_driver function


************************************************************************/
static int sh_sir_probe(struct platform_device *pdev)
{
	struct net_device *ndev;
	struct sh_sir_self *self;
	struct resource *res;
	char clk_name[8];
	int irq;
	int err = -ENOMEM;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	irq = platform_get_irq(pdev, 0);
	if (!res || irq < 0) {
		dev_err(&pdev->dev, "Not enough platform resources.\n");
		goto exit;
	}

	ndev = alloc_irdadev(sizeof(*self));
	if (!ndev)
		goto exit;

	self = netdev_priv(ndev);
	self->membase = ioremap_nocache(res->start, resource_size(res));
	if (!self->membase) {
		err = -ENXIO;
		dev_err(&pdev->dev, "Unable to ioremap.\n");
		goto err_mem_1;
	}

	err = sh_sir_init_iobuf(self, IRDA_SKB_MAX_MTU, IRDA_SIR_MAX_FRAME);
	if (err)
		goto err_mem_2;

	snprintf(clk_name, sizeof(clk_name), "irda%d", pdev->id);
	self->clk = clk_get(&pdev->dev, clk_name);
	if (IS_ERR(self->clk)) {
		dev_err(&pdev->dev, "cannot get clock \"%s\"\n", clk_name);
		err = -ENODEV;
		goto err_mem_3;
	}

	irda_init_max_qos_capabilies(&self->qos);

	ndev->netdev_ops	= &sh_sir_ndo;
	ndev->irq		= irq;

	self->ndev			= ndev;
	self->qos.baud_rate.bits	&= IR_9600; /* FIXME */
	self->qos.min_turn_time.bits	= 1; /* 10 ms or more */

	irda_qos_bits_to_value(&self->qos);

	err = register_netdev(ndev);
	if (err)
		goto err_mem_4;

	platform_set_drvdata(pdev, ndev);
	err = devm_request_irq(&pdev->dev, irq, sh_sir_irq, 0, "sh_sir", self);
	if (err) {
		dev_warn(&pdev->dev, "Unable to attach sh_sir interrupt\n");
		goto err_mem_4;
	}

	dev_info(&pdev->dev, "SuperH IrDA probed\n");

	goto exit;

err_mem_4:
	clk_put(self->clk);
err_mem_3:
	sh_sir_remove_iobuf(self);
err_mem_2:
	iounmap(self->membase);
err_mem_1:
	free_netdev(ndev);
exit:
	return err;
}

static int sh_sir_remove(struct platform_device *pdev)
{
	struct net_device *ndev = platform_get_drvdata(pdev);
	struct sh_sir_self *self = netdev_priv(ndev);

	if (!self)
		return 0;

	unregister_netdev(ndev);
	clk_put(self->clk);
	sh_sir_remove_iobuf(self);
	iounmap(self->membase);
	free_netdev(ndev);

	return 0;
}

static struct platform_driver sh_sir_driver = {
	.probe   = sh_sir_probe,
	.remove  = sh_sir_remove,
	.driver  = {
		.name = DRIVER_NAME,
	},
};

module_platform_driver(sh_sir_driver);

MODULE_AUTHOR("Kuninori Morimoto <morimoto.kuninori@renesas.com>");
MODULE_DESCRIPTION("SuperH IrDA driver");
MODULE_LICENSE("GPL");