spi: fsl-espi: fix support for all available clock rates

According to NXP ESPI datasheet, the SPI clock rate is:

    spi_clk = System_Clock / ( 2 * DIV16 * ( 1 + PM ) )

Where System_Clock is the platform clock divided by 2,
DIV16 may be 1 or 16, and PM is a 4 bits integer (0 to 15).

Isolating PM on the expression, we get:

    PM = (System_Clock / ( 2 * DIV16 * spi_clk ) ) - 1

Where System_Clock = mpc8xxx_spi->spibrg / 2, spi_clk = hz,
and DIV16 = 1 or DIV16 = 16. So,

    PM = (mpc8xxx_spi->spibrg / ( 4 * hz) ) - 1
or
    PM = (mpc8xxx_spi->spibrg / ( 16 * 4 * hz) ) - 1

Current spi-fsl-espi driver can't configure the HW for all
supported clock rates. It filters out clock rates for PM = 0
and PM = 1.

This patch allows all range of supported clock rates to be
configured on the ESPI controller.

Signed-off-by: Paulo Zaneti <paulo.zaneti@datacom.ind.br>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 12 insertions, 16 deletions

diff --git a/drivers/spi/spi-fsl-espi.c b/drivers/spi/spi-fsl-espi.c

path: root/proto.h

/*
 * netsniff-ng - the packet sniffing beast
 * Copyright (C) 2009, 2010 Daniel Borkmann
 * Copyright (C) 2012 Christoph Jaeger <christoph@netsniff-ng.org>
 * Subject to the GPL, version 2.
 */

#ifndef PROTO_H
#define PROTO_H

#include <ctype.h>
#include <stdint.h>

#include "hash.h"
#include "tprintf.h"

struct pkt_buff;

struct protocol {
	/* Needs to be filled out by user */
	unsigned int key;
	void (*print_full)(struct pkt_buff *pkt);
	void (*print_less)(struct pkt_buff *pkt);
	/* Used by program logic */
	struct protocol *next;
	void (*process)   (struct pkt_buff *pkt);
};

extern void empty(struct pkt_buff *pkt);
extern void hex(struct pkt_buff *pkt);
extern void ascii(struct pkt_buff *pkt);
extern void hex_ascii(struct pkt_buff *pkt);

#endif /* PROTO_H */