include/linux/hdlcdrv.h

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * hdlcdrv.h  -- HDLC packet radio network driver.
 * The Linux soundcard driver for 1200 baud and 9600 baud packet radio
 * (C) 1996-1998 by Thomas Sailer, HB9JNX/AE4WA
 */
#ifndef _HDLCDRV_H
#define _HDLCDRV_H


#include <linux/netdevice.h>
#include <linux/if.h>
#include <linux/spinlock.h>
#include <uapi/linux/hdlcdrv.h>

#define HDLCDRV_MAGIC      0x5ac6e778
#define HDLCDRV_HDLCBUFFER  32 /* should be a power of 2 for speed reasons */
#define HDLCDRV_BITBUFFER  256 /* should be a power of 2 for speed reasons */
#undef HDLCDRV_LOOPBACK  /* define for HDLC debugging purposes */
#define HDLCDRV_DEBUG

/* maximum packet length, excluding CRC */
#define HDLCDRV_MAXFLEN             400	


struct hdlcdrv_hdlcbuffer {
	spinlock_t lock;
	unsigned rd, wr;
	unsigned short buf[HDLCDRV_HDLCBUFFER];
};

#ifdef HDLCDRV_DEBUG
struct hdlcdrv_bitbuffer {
	unsigned int rd;
	unsigned int wr;
	unsigned int shreg;
	unsigned char buffer[HDLCDRV_BITBUFFER];
};

static inline void hdlcdrv_add_bitbuffer(struct hdlcdrv_bitbuffer *buf, 
					 unsigned int bit)
{
	unsigned char new;

	new = buf->shreg & 1;
	buf->shreg >>= 1;
	buf->shreg |= (!!bit) << 7;
	if (new) {
		buf->buffer[buf->wr] = buf->shreg;
		buf->wr = (buf->wr+1) % sizeof(buf->buffer);
		buf->shreg = 0x80;
	}
}

static inline void hdlcdrv_add_bitbuffer_word(struct hdlcdrv_bitbuffer *buf, 
					      unsigned int bits)
{
	buf->buffer[buf->wr] = bits & 0xff;
	buf->wr = (buf->wr+1) % sizeof(buf->buffer);
	buf->buffer[buf->wr] = (bits >> 8) & 0xff;
	buf->wr = (buf->wr+1) % sizeof(buf->buffer);

}
#endif /* HDLCDRV_DEBUG */

/* -------------------------------------------------------------------- */
/*
 * Information that need to be kept for each driver. 
 */

struct hdlcdrv_ops {
	/*
	 * first some informations needed by the hdlcdrv routines
	 */
	const char *drvname;
	const char *drvinfo;
	/*
	 * the routines called by the hdlcdrv routines
	 */
	int (*open)(struct net_device *);
	int (*close)(struct net_device *);
	int (*ioctl)(struct net_device *, struct ifreq *, 
		     struct hdlcdrv_ioctl *, int);
};

struct hdlcdrv_state {
	int magic;
	int opened;

	const struct hdlcdrv_ops *ops;

	struct {
		int bitrate;
	} par;

	struct hdlcdrv_pttoutput {
		int dma2;
		int seriobase;
		int pariobase;
		int midiiobase;
		unsigned int flags;
	} ptt_out;

	struct hdlcdrv_channel_params ch_params;

	struct hdlcdrv_hdlcrx {
		struct hdlcdrv_hdlcbuffer hbuf;
		unsigned long in_hdlc_rx;
		/* 0 = sync hunt, != 0 receiving */
		int rx_state;	
		unsigned int bitstream;
		unsigned int bitbuf;
		int numbits;
		unsigned char dcd;
		
		int len;
		unsigned char *bp;
		unsigned char buffer[HDLCDRV_MAXFLEN+2];
	} hdlcrx;

	struct hdlcdrv_hdlctx {
		struct hdlcdrv_hdlcbuffer hbuf;
		unsigned long in_hdlc_tx;
		/*
		 * 0 = send flags
		 * 1 = send txtail (flags)
		 * 2 = send packet
		 */
		int tx_state;	
		int numflags;
		unsigned int bitstream;
		unsigned char ptt;
		int calibrate;
		int slotcnt;

		unsigned int bitbuf;
		int numbits;
		
		int len;
		unsigned char *bp;
		unsigned char buffer[HDLCDRV_MAXFLEN+2];
	} hdlctx;

#ifdef HDLCDRV_DEBUG
	struct hdlcdrv_bitbuffer bitbuf_channel;
	struct hdlcdrv_bitbuffer bitbuf_hdlc;
#endif /* HDLCDRV_DEBUG */

	int ptt_keyed;

	/* queued skb for transmission */
	struct sk_buff *skb;
};


/* -------------------------------------------------------------------- */

static inline int hdlcdrv_hbuf_full(struct hdlcdrv_hdlcbuffer *hb) 
{
	unsigned long flags;
	int ret;
	
	spin_lock_irqsave(&hb->lock, flags);
	ret = !((HDLCDRV_HDLCBUFFER - 1 + hb->rd - hb->wr) % HDLCDRV_HDLCBUFFER);
	spin_unlock_irqrestore(&hb->lock, flags);
	return ret;
}

/* -------------------------------------------------------------------- */

static inline int hdlcdrv_hbuf_empty(struct hdlcdrv_hdlcbuffer *hb)
{
	unsigned long flags;
	int ret;
	
	spin_lock_irqsave(&hb->lock, flags);
	ret = (hb->rd == hb->wr);
	spin_unlock_irqrestore(&hb->lock, flags);
	return ret;
}

/* -------------------------------------------------------------------- */

static inline unsigned short hdlcdrv_hbuf_get(struct hdlcdrv_hdlcbuffer *hb)
{
	unsigned long flags;
	unsigned short val;
	unsigned newr;

	spin_lock_irqsave(&hb->lock, flags);
	if (hb->rd == hb->wr)
		val = 0;
	else {
		newr = (hb->rd+1) % HDLCDRV_HDLCBUFFER;
		val = hb->buf[hb->rd];
		hb->rd = newr;
	}
	spin_unlock_irqrestore(&hb->lock, flags);
	return val;
}

/* -------------------------------------------------------------------- */

static inline void hdlcdrv_hbuf_put(struct hdlcdrv_hdlcbuffer *hb, 
				    unsigned short val)
{
	unsigned newp;
	unsigned long flags;
	
	spin_lock_irqsave(&hb->lock, flags);
	newp = (hb->wr+1) % HDLCDRV_HDLCBUFFER;
	if (newp != hb->rd) { 
		hb->buf[hb->wr] = val & 0xffff;
		hb->wr = newp;
	}
	spin_unlock_irqrestore(&hb->lock, flags);
}

/* -------------------------------------------------------------------- */

static inline void hdlcdrv_putbits(struct hdlcdrv_state *s, unsigned int bits)
{
	hdlcdrv_hbuf_put(&s->hdlcrx.hbuf, bits);
}

static inline unsigned int hdlcdrv_getbits(struct hdlcdrv_state *s)
{
	unsigned int ret;

	if (hdlcdrv_hbuf_empty(&s->hdlctx.hbuf)) {
		if (s->hdlctx.calibrate > 0)
			s->hdlctx.calibrate--;
		else
			s->hdlctx.ptt = 0;
		ret = 0;
	} else 
		ret = hdlcdrv_hbuf_get(&s->hdlctx.hbuf);
#ifdef HDLCDRV_LOOPBACK
	hdlcdrv_hbuf_put(&s->hdlcrx.hbuf, ret);
#endif /* HDLCDRV_LOOPBACK */
	return ret;
}

static inline void hdlcdrv_channelbit(struct hdlcdrv_state *s, unsigned int bit)
{
#ifdef HDLCDRV_DEBUG
	hdlcdrv_add_bitbuffer(&s->bitbuf_channel, bit);
#endif /* HDLCDRV_DEBUG */
}

static inline void hdlcdrv_setdcd(struct hdlcdrv_state *s, int dcd)
{
	s->hdlcrx.dcd = !!dcd;
}

static inline int hdlcdrv_ptt(struct hdlcdrv_state *s)
{
	return s->hdlctx.ptt || (s->hdlctx.calibrate > 0);
}

/* -------------------------------------------------------------------- */

void hdlcdrv_receiver(struct net_device *, struct hdlcdrv_state *);
void hdlcdrv_transmitter(struct net_device *, struct hdlcdrv_state *);
void hdlcdrv_arbitrate(struct net_device *, struct hdlcdrv_state *);
struct net_device *hdlcdrv_register(const struct hdlcdrv_ops *ops,
				    unsigned int privsize, const char *ifname,
				    unsigned int baseaddr, unsigned int irq, 
				    unsigned int dma);
void hdlcdrv_unregister(struct net_device *dev);

/* -------------------------------------------------------------------- */



#endif /* _HDLCDRV_H */