scc.h

/*
 * atari_SCC.h: Definitions for the Am8530 Serial Communications Controller
 *
 * Copyright 1994 Roman Hodek <Roman.Hodek@informatik.uni-erlangen.de>
 *
 * 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.
 *
 */


#ifndef _SCC_H
#define _SCC_H

#include <linux/delay.h>

/* Special configuration ioctls for the Atari SCC5380 Serial
 * Communications Controller
 */

/* ioctl command codes */

#define TIOCGATSCC	0x54c0	/* get SCC configuration */
#define TIOCSATSCC	0x54c1	/* set SCC configuration */
#define TIOCDATSCC	0x54c2	/* reset configuration to defaults */

/* Clock sources */

#define CLK_RTxC	0
#define CLK_TRxC	1
#define CLK_PCLK	2

/* baud_bases for the common clocks in the Atari. These are the real
 * frequencies divided by 16.
 */
   
#define SCC_BAUD_BASE_TIMC	19200	/* 0.3072 MHz from TT-MFP, Timer C */
#define SCC_BAUD_BASE_BCLK	153600	/* 2.4576 MHz */
#define SCC_BAUD_BASE_PCLK4	229500	/* 3.6720 MHz */
#define SCC_BAUD_BASE_PCLK	503374	/* 8.0539763 MHz */
#define SCC_BAUD_BASE_NONE	0	/* for not connected or unused
					 * clock sources */

/* The SCC clock configuration structure */

struct scc_clock_config {
	unsigned	RTxC_base;	/* base_baud of RTxC */
	unsigned	TRxC_base;	/* base_baud of TRxC */
	unsigned	PCLK_base;	/* base_baud of PCLK, both channels! */
	struct {
		unsigned clksrc;	/* CLK_RTxC, CLK_TRxC or CLK_PCLK */
		unsigned divisor;	/* divisor for base baud, valid values:
					 * see below */
	} baud_table[17];		/* For 50, 75, 110, 135, 150, 200, 300,
					 * 600, 1200, 1800, 2400, 4800, 9600,
					 * 19200, 38400, 57600 and 115200 bps.
					 * The last two could be replaced by
					 * other rates > 38400 if they're not
					 * possible.
					 */
};

/* The following divisors are valid:
 *
 *   - CLK_RTxC: 1 or even (1, 2 and 4 are the direct modes, > 4 use
 *               the BRG)
 *
 *   - CLK_TRxC: 1, 2 or 4 (no BRG, only direct modes possible)
 *
 *   - CLK_PCLK: >= 4 and even (no direct modes, only BRG)
 *
 */

struct scc_port {
	struct gs_port		gs;
	volatile unsigned char	*ctrlp;
	volatile unsigned char	*datap;
	int			x_char;		/* xon/xoff character */
	int			c_dcd;
	int			channel;
	struct scc_port		*port_a;	/* Reference to port A and B */
	struct scc_port		*port_b;	/*   structs for reg access  */
};

#define SCC_MAGIC	0x52696368

/***********************************************************************/
/*                                                                     */
/*                             Register Names                          */
/*                                                                     */
/***********************************************************************/

/* The SCC documentation gives no explicit names to the registers,
 * they're just called WR0..15 and RR0..15. To make the source code
 * better readable and make the transparent write reg read access (see
 * below) possible, I christen them here with self-invented names.
 * Note that (real) read registers are assigned numbers 16..31. WR7'
 * has number 33.
 */

#define	COMMAND_REG		0	/* wo */
#define	INT_AND_DMA_REG		1	/* wo */
#define	INT_VECTOR_REG		2	/* rw, common to both channels */
#define	RX_CTRL_REG		3	/* rw */
#define	AUX1_CTRL_REG		4	/* rw */
#define	TX_CTRL_REG		5	/* rw */
#define	SYNC_ADR_REG		6	/* wo */
#define	SYNC_CHAR_REG		7	/* wo */
#define	SDLC_OPTION_REG		33	/* wo */
#define	TX_DATA_REG		8	/* wo */
#define	MASTER_INT_CTRL		9	/* wo, common to both channels */
#define	AUX2_CTRL_REG		10	/* rw */
#define	CLK_CTRL_REG		11	/* wo */
#define	TIMER_LOW_REG		12	/* rw */
#define	TIMER_HIGH_REG		13	/* rw */
#define	DPLL_CTRL_REG		14	/* wo */
#define	INT_CTRL_REG		15	/* rw */

#define	STATUS_REG		16	/* ro */
#define	SPCOND_STATUS_REG	17	/* wo */
/* RR2 is WR2 for Channel A, Channel B gives vector + current status: */
#define	CURR_VECTOR_REG		18	/* Ch. B only, Ch. A for rw */
#define	INT_PENDING_REG		19	/* Channel A only! */
/* RR4 is WR4, if b6(MR7') == 1 */
/* RR5 is WR5, if b6(MR7') == 1 */
#define	FS_FIFO_LOW_REG		22	/* ro */
#define	FS_FIFO_HIGH_REG	23	/* ro */
#define	RX_DATA_REG		24	/* ro */
/* RR9 is WR3, if b6(MR7') == 1 */
#define	DPLL_STATUS_REG		26	/* ro */
/* RR11 is WR10, if b6(MR7') == 1 */
/* RR12 is WR12 */
/* RR13 is WR13 */
/* RR14 not present */
/* RR15 is WR15 */


/***********************************************************************/
/*                                                                     */
/*                             Register Values                         */
/*                                                                     */
/***********************************************************************/


/* WR0: COMMAND_REG "CR" */

#define	CR_RX_CRC_RESET		0x40
#define	CR_TX_CRC_RESET		0x80
#define	CR_TX_UNDERRUN_RESET	0xc0

#define	CR_EXTSTAT_RESET	0x10
#define	CR_SEND_ABORT		0x18
#define	CR_ENAB_INT_NEXT_RX	0x20
#define	CR_TX_PENDING_RESET	0x28
#define	CR_ERROR_RESET		0x30
#define	CR_HIGHEST_IUS_RESET	0x38


/* WR1: INT_AND_DMA_REG "IDR" */

#define	IDR_EXTSTAT_INT_ENAB	0x01
#define	IDR_TX_INT_ENAB		0x02
#define	IDR_PARERR_AS_SPCOND	0x04

#define	IDR_RX_INT_DISAB	0x00
#define	IDR_RX_INT_FIRST	0x08
#define	IDR_RX_INT_ALL		0x10
#define	IDR_RX_INT_SPCOND	0x18
#define	IDR_RX_INT_MASK		0x18

#define	IDR_WAITREQ_RX		0x20
#define	IDR_WAITREQ_IS_REQ	0x40
#define	IDR_WAITREQ_ENAB	0x80


/* WR3: RX_CTRL_REG "RCR" */

#define	RCR_RX_ENAB		0x01
#define	RCR_DISCARD_SYNC_CHARS	0x02
#define	RCR_ADDR_SEARCH		0x04
#define	RCR_CRC_ENAB		0x08
#define	RCR_SEARCH_MODE		0x10
#define	RCR_AUTO_ENAB_MODE	0x20

#define	RCR_CHSIZE_MASK		0xc0
#define	RCR_CHSIZE_5		0x00
#define	RCR_CHSIZE_6		0x40
#define	RCR_CHSIZE_7		0x80
#define	RCR_CHSIZE_8		0xc0


/* WR4: AUX1_CTRL_REG "A1CR" */

#define	A1CR_PARITY_MASK	0x03
#define	A1CR_PARITY_NONE	0x00
#define	A1CR_PARITY_ODD		0x01
#define	A1CR_PARITY_EVEN	0x03

#define	A1CR_MODE_MASK		0x0c
#define	A1CR_MODE_SYNCR		0x00
#define	A1CR_MODE_ASYNC_1	0x04
#define	A1CR_MODE_ASYNC_15	0x08
#define	A1CR_MODE_ASYNC_2	0x0c

#define	A1CR_SYNCR_MODE_MASK	0x30
#define	A1CR_SYNCR_MONOSYNC	0x00
#define	A1CR_SYNCR_BISYNC	0x10
#define	A1CR_SYNCR_SDLC		0x20
#define	A1CR_SYNCR_EXTCSYNC	0x30

#define	A1CR_CLKMODE_MASK	0xc0
#define	A1CR_CLKMODE_x1		0x00
#define	A1CR_CLKMODE_x16	0x40
#define	A1CR_CLKMODE_x32	0x80
#define	A1CR_CLKMODE_x64	0xc0


/* WR5: TX_CTRL_REG "TCR" */

#define	TCR_TX_CRC_ENAB		0x01
#define	TCR_RTS			0x02
#define	TCR_USE_CRC_CCITT	0x00
#define	TCR_USE_CRC_16		0x04
#define	TCR_TX_ENAB		0x08
#define	TCR_SEND_BREAK		0x10

#define	TCR_CHSIZE_MASK		0x60
#define	TCR_CHSIZE_5		0x00
#define	TCR_CHSIZE_6		0x20
#define	TCR_CHSIZE_7		0x40
#define	TCR_CHSIZE_8		0x60

#define	TCR_DTR			0x80


/* WR7': SLDC_OPTION_REG "SOR" */

#define	SOR_AUTO_TX_ENAB	0x01
#define	SOR_AUTO_EOM_RESET	0x02
#define	SOR_AUTO_RTS_MODE	0x04
#define	SOR_NRZI_DISAB_HIGH	0x08
#define	SOR_ALT_DTRREQ_TIMING	0x10
#define	SOR_READ_CRC_CHARS	0x20
#define	SOR_EXTENDED_REG_ACCESS	0x40


/* WR9: MASTER_INT_CTRL "MIC" */

#define	MIC_VEC_INCL_STAT	0x01
#define	MIC_NO_VECTOR		0x02
#define	MIC_DISAB_LOWER_CHAIN	0x04
#define	MIC_MASTER_INT_ENAB	0x08
#define	MIC_STATUS_HIGH		0x10
#define	MIC_IGN_INTACK		0x20

#define	MIC_NO_RESET		0x00
#define	MIC_CH_A_RESET		0x40
#define	MIC_CH_B_RESET		0x80
#define	MIC_HARD_RESET		0xc0


/* WR10: AUX2_CTRL_REG "A2CR" */

#define	A2CR_SYNC_6		0x01
#define	A2CR_LOOP_MODE		0x02
#define	A2CR_ABORT_ON_UNDERRUN	0x04
#define	A2CR_MARK_IDLE		0x08
#define	A2CR_GO_ACTIVE_ON_POLL	0x10

#define	A2CR_CODING_MASK	0x60
#define	A2CR_CODING_NRZ		0x00
#define	A2CR_CODING_NRZI	0x20
#define	A2CR_CODING_FM1		0x40
#define	A2CR_CODING_FM0		0x60

#define	A2CR_PRESET_CRC_1	0x80


/* WR11: CLK_CTRL_REG "CCR" */

#define	CCR_TRxCOUT_MASK	0x03
#define	CCR_TRxCOUT_XTAL	0x00
#define	CCR_TRxCOUT_TXCLK	0x01
#define	CCR_TRxCOUT_BRG		0x02
#define	CCR_TRxCOUT_DPLL	0x03

#define	CCR_TRxC_OUTPUT		0x04

#define	CCR_TXCLK_MASK		0x18
#define	CCR_TXCLK_RTxC		0x00
#define	CCR_TXCLK_TRxC		0x08
#define	CCR_TXCLK_BRG		0x10
#define	CCR_TXCLK_DPLL		0x18

#define	CCR_RXCLK_MASK		0x60
#define	CCR_RXCLK_RTxC		0x00
#define	CCR_RXCLK_TRxC		0x20
#define	CCR_RXCLK_BRG		0x40
#define	CCR_RXCLK_DPLL		0x60

#define	CCR_RTxC_XTAL		0x80


/* WR14: DPLL_CTRL_REG "DCR" */

#define	DCR_BRG_ENAB		0x01
#define	DCR_BRG_USE_PCLK	0x02
#define	DCR_DTRREQ_IS_REQ	0x04
#define	DCR_AUTO_ECHO		0x08
#define	DCR_LOCAL_LOOPBACK	0x10

#define	DCR_DPLL_EDGE_SEARCH	0x20
#define	DCR_DPLL_ERR_RESET	0x40
#define	DCR_DPLL_DISAB		0x60
#define	DCR_DPLL_CLK_BRG	0x80
#define	DCR_DPLL_CLK_RTxC	0xa0
#define	DCR_DPLL_FM		0xc0
#define	DCR_DPLL_NRZI		0xe0


/* WR15: INT_CTRL_REG "ICR" */

#define	ICR_OPTIONREG_SELECT	0x01
#define	ICR_ENAB_BRG_ZERO_INT	0x02
#define	ICR_USE_FS_FIFO		0x04
#define	ICR_ENAB_DCD_INT	0x08
#define	ICR_ENAB_SYNC_INT	0x10
#define	ICR_ENAB_CTS_INT	0x20
#define	ICR_ENAB_UNDERRUN_INT	0x40
#define	ICR_ENAB_BREAK_INT	0x80


/* RR0: STATUS_REG "SR" */

#define	SR_CHAR_AVAIL		0x01
#define	SR_BRG_ZERO		0x02
#define	SR_TX_BUF_EMPTY		0x04
#define	SR_DCD			0x08
#define	SR_SYNC_ABORT		0x10
#define	SR_CTS			0x20
#define	SR_TX_UNDERRUN		0x40
#define	SR_BREAK		0x80


/* RR1: SPCOND_STATUS_REG "SCSR" */

#define	SCSR_ALL_SENT		0x01
#define	SCSR_RESIDUAL_MASK	0x0e
#define	SCSR_PARITY_ERR		0x10
#define	SCSR_RX_OVERRUN		0x20
#define	SCSR_CRC_FRAME_ERR	0x40
#define	SCSR_END_OF_FRAME	0x80


/* RR3: INT_PENDING_REG "IPR" */

#define	IPR_B_EXTSTAT		0x01
#define	IPR_B_TX		0x02
#define	IPR_B_RX		0x04
#define	IPR_A_EXTSTAT		0x08
#define	IPR_A_TX		0x10
#define	IPR_A_RX		0x20


/* RR7: FS_FIFO_HIGH_REG "FFHR" */

#define	FFHR_CNT_MASK		0x3f
#define	FFHR_IS_FROM_FIFO	0x40
#define	FFHR_FIFO_OVERRUN	0x80


/* RR10: DPLL_STATUS_REG "DSR" */

#define	DSR_ON_LOOP		0x02
#define	DSR_ON_LOOP_SENDING	0x10
#define	DSR_TWO_CLK_MISSING	0x40
#define	DSR_ONE_CLK_MISSING	0x80

/***********************************************************************/
/*                                                                     */
/*                             Register Access                         */
/*                                                                     */
/***********************************************************************/


/* The SCC needs 3.5 PCLK cycles recovery time between to register
 * accesses. PCLK runs with 8 MHz on an Atari, so this delay is 3.5 *
 * 125 ns = 437.5 ns. This is too short for udelay().
 * 10/16/95: A tstb st_mfp.par_dt_reg takes 600ns (sure?) and thus should be
 * quite right
 */

#define scc_reg_delay() \
    do {			\
	if (MACH_IS_MVME16x || MACH_IS_BVME6000 || MACH_IS_MVME147)	\
		__asm__ __volatile__ ( " nop; nop");			\
	else if (MACH_IS_ATARI)						\
		__asm__ __volatile__ ( "tstb %0" : : "g" (*_scc_del) : "cc" );\
    } while (0)

static unsigned char scc_shadow[2][16];

/* The following functions should relax the somehow complicated
 * register access of the SCC. _SCCwrite() stores all written values
 * (except for WR0 and WR8) in shadow registers for later recall. This
 * removes the burden of remembering written values as needed. The
 * extra work of storing the value doesn't count, since a delay is
 * needed after a SCC access anyway. Additionally, _SCCwrite() manages
 * writes to WR0 and WR8 differently, because these can be accessed
 * directly with less overhead. Another special case are WR7 and WR7'.
 * _SCCwrite automatically checks what of this registers is selected
 * and changes b0 of WR15 if needed.
 * 
 * _SCCread() for standard read registers is straightforward, except
 * for RR2 (split into two "virtual" registers: one for the value
 * written to WR2 (from the shadow) and one for the vector including
 * status from RR2, Ch. B) and RR3. The latter must be read from
 * Channel A, because it reads as all zeros on Ch. B. RR0 and RR8 can
 * be accessed directly as before.
 * 
 * The two inline function contain complicated switch statements. But
 * I rely on regno and final_delay being constants, so gcc can reduce
 * the whole stuff to just some assembler statements.
 * 
 * _SCCwrite and _SCCread aren't intended to be used directly under
 * normal circumstances. The macros SCCread[_ND] and SCCwrite[_ND] are
 * for that purpose. They assume that a local variable 'port' is
 * declared and pointing to the port's scc_struct entry. The
 * variants with "_NB" appended should be used if no other SCC
 * accesses follow immediately (within 0.5 usecs). They just skip the
 * final delay nops.
 * 
 * Please note that accesses to SCC registers should only take place
 * when interrupts are turned off (at least if SCC interrupts are
 * enabled). Otherwise, an interrupt could interfere with the
 * two-stage accessing process.
 *
 */


static __inline__ void _SCCwrite(
	struct scc_port *port,
	unsigned char *shadow,
	volatile unsigned char *_scc_del,
	int regno,
	unsigned char val, int final_delay )
{
	switch( regno ) {

	  case COMMAND_REG:
		/* WR0 can be written directly without pointing */
		*port->ctrlp = val;
		break;

	  case SYNC_CHAR_REG:
		/* For WR7, first set b0 of WR15 to 0, if needed */
		if (shadow[INT_CTRL_REG] & ICR_OPTIONREG_SELECT) {
			*port->ctrlp = 15;
			shadow[INT_CTRL_REG] &= ~ICR_OPTIONREG_SELECT;
			scc_reg_delay();
			*port->ctrlp = shadow[INT_CTRL_REG];
			scc_reg_delay();
		}
		goto normal_case;
		
	  case SDLC_OPTION_REG:
		/* For WR7', first set b0 of WR15 to 1, if needed */
		if (!(shadow[INT_CTRL_REG] & ICR_OPTIONREG_SELECT)) {
			*port->ctrlp = 15;
			shadow[INT_CTRL_REG] |= ICR_OPTIONREG_SELECT;
			scc_reg_delay();
			*port->ctrlp = shadow[INT_CTRL_REG];
			scc_reg_delay();
		}
		*port->ctrlp = 7;
		shadow[8] = val;	/* WR7' shadowed at WR8 */
		scc_reg_delay();
		*port->ctrlp = val;
		break;

	  case TX_DATA_REG:		/* WR8 */
		/* TX_DATA_REG can be accessed directly on some h/w */
		if (MACH_IS_MVME16x || MACH_IS_BVME6000 || MACH_IS_MVME147)
		{
			*port->ctrlp = regno;
			scc_reg_delay();
			*port->ctrlp = val;
		}
		else
			*port->datap = val;
		break;

	  case MASTER_INT_CTRL:
		*port->ctrlp = regno;
		val &= 0x3f;	/* bits 6..7 are the reset commands */
		scc_shadow[0][regno] = val;
		scc_reg_delay();
		*port->ctrlp = val;
		break;

	  case DPLL_CTRL_REG:
		*port->ctrlp = regno;
		val &= 0x1f;			/* bits 5..7 are the DPLL commands */
		shadow[regno] = val;
		scc_reg_delay();
		*port->ctrlp = val;
		break;

	  case 1 ... 6:	
	  case 10 ... 13:
	  case 15:
	  normal_case:
		*port->ctrlp = regno;
		shadow[regno] = val;
		scc_reg_delay();
		*port->ctrlp = val;
		break;
		
	  default:
		printk( "Bad SCC write access to WR%d\n", regno );
		break;
		
	}

	if (final_delay)
		scc_reg_delay();
}


static __inline__ unsigned char _SCCread(
	struct scc_port *port,
	unsigned char *shadow,
	volatile unsigned char *_scc_del,
	int regno, int final_delay )
{
	unsigned char rv;

	switch( regno ) {

		/* --- real read registers --- */
	  case STATUS_REG:
		rv = *port->ctrlp;
		break;

	  case INT_PENDING_REG:
		/* RR3: read only from Channel A! */
		port = port->port_a;
		goto normal_case;

	  case RX_DATA_REG:
		/* RR8 can be accessed directly on some h/w */
		if (MACH_IS_MVME16x || MACH_IS_BVME6000 || MACH_IS_MVME147)
		{
			*port->ctrlp = 8;
			scc_reg_delay();
			rv = *port->ctrlp;
		}
		else
			rv = *port->datap;
		break;

	  case CURR_VECTOR_REG:
		/* RR2 (vector including status) from Ch. B */
		port = port->port_b;
		goto normal_case;
		
		/* --- reading write registers: access the shadow --- */
	  case 1 ... 7:
	  case 10 ... 15:
		return shadow[regno]; /* no final delay! */

		/* WR7' is special, because it is shadowed at the place of WR8 */
	  case SDLC_OPTION_REG:
		return shadow[8]; /* no final delay! */

		/* WR9 is special too, because it is common for both channels */
	  case MASTER_INT_CTRL:
		return scc_shadow[0][9]; /* no final delay! */

	  default:
		printk( "Bad SCC read access to %cR%d\n", (regno & 16) ? 'R' : 'W',
				regno & ~16 );
		break;
		
	  case SPCOND_STATUS_REG:
	  case FS_FIFO_LOW_REG:
	  case FS_FIFO_HIGH_REG:
	  case DPLL_STATUS_REG:
	  normal_case:
		*port->ctrlp = regno & 0x0f;
		scc_reg_delay();
		rv = *port->ctrlp;
		break;
		
	}

	if (final_delay)
		scc_reg_delay();
	return rv;
}

#define SCC_ACCESS_INIT(port)						\
	unsigned char *_scc_shadow = &scc_shadow[port->channel][0]

#define	SCCwrite(reg,val)	_SCCwrite(port,_scc_shadow,scc_del,(reg),(val),1)
#define	SCCwrite_NB(reg,val)	_SCCwrite(port,_scc_shadow,scc_del,(reg),(val),0)
#define	SCCread(reg)		_SCCread(port,_scc_shadow,scc_del,(reg),1)
#define	SCCread_NB(reg)		_SCCread(port,_scc_shadow,scc_del,(reg),0)

#define SCCmod(reg,and,or)	SCCwrite((reg),(SCCread(reg)&(and))|(or))

#endif /* _SCC_H */