[U-Boot] [PATCH V3] Davinci: add a pin multiplexer configuration API

[Tom]

Nick Thompson wrote:
> Davinci: add a pin multiplexer configuration API.
> 
> Creates a method allowing pin settings to be logically grouped into data
> structure arrays and provids an API to configure the PINMUX settings to
> enable the relevant pin functions.
> 
> Signed-off-by: Nick Thompson <nick.thompson at gefanuc.com>
> ---
> Applies to: u-boot-ti
> 
> Changes from last patch:
> 	removed compiler warning (implicit type cast)
> 
> The PINMUXn definitions are already present in hardware.h.
> 
> The number of PINMUX fields per register and the width of the fields
> needs to be set per SoC. The initial settings are appropriate for at least
> DA8xx devices. These should be modified in misc.h to support other devices
> as required.
> 
>  board/davinci/common/misc.c |   47 ++++++++++++++++++++++++++++++++++++++++++-
>  board/davinci/common/misc.h |   12 +++++++++++
>  2 files changed, 58 insertions(+), 1 deletions(-)
> 
> diff --git a/board/davinci/common/misc.c b/board/davinci/common/misc.c
> index ffdc20b..9c05f3e 100644
> --- a/board/davinci/common/misc.c
> +++ b/board/davinci/common/misc.c
> @@ -1,6 +1,7 @@
>  /*
>   * Miscelaneous DaVinci functions.
>   *
> + * Copyright (C) 2009 Nick Thompson, GE Fanuc Ltd, <nick.thompson at gefanuc.com>
>   * Copyright (C) 2007 Sergey Kubushyn <ksi at koi8.net>
>   * Copyright (C) 2008 Lyrtech <www.lyrtech.com>
>   * Copyright (C) 2004 Texas Instruments.
> @@ -27,7 +28,8 @@
>  #include <i2c.h>
>  #include <net.h>
>  #include <asm/arch/hardware.h>
> -
> +#include <asm/io.h>
> +#include "misc.h"
>  
>  DECLARE_GLOBAL_DATA_PTR;
>  
> @@ -109,3 +111,46 @@ void dv_configure_mac_address(uint8_t *rom_enetaddr)
>  }
>  
>  #endif	/* DAVINCI_EMAC */
> +
> +/*
> + * Change the setting of a pin multiplexer field.
> + *
> + * Takes an array of pinmux settings similar to:
> + *
> + * struct pinmux_config uart_pins[] = {
> + *	{ PINMUX8, 2, 7 },
> + *	{ PINMUX9, 2, 0 }

Change to match lowercasing of next patches

> + * };
> + *
> + * Stepping through the array, each PINMUXn register has the given value
> + * set in the pin mux field specified.
> + *
> + * The number of pins in the array must be passed (ARRAY_SIZE can provide
> + * this value conveniently).
> + *
> + * Returns 0 if all field numbers and values are in the correct range,
> + * else returns -1.
> + */
> +int davinci_configure_pin_mux(const struct pinmux_config *pins, int n_pins)
> +{
> +	int i;
> +

It would be better if this loop was broken into an error checker
and a mux setter.

If there is an error, the mux pins will be left half done.

> +	for (i = 0; i < n_pins; i++) {
> +		int value = pins[i].value;

Why extend value with an int?
better to use unsigned int.

> +		const int field = pins[i].field;
> +
> +		if (field < PIN_MUX_NUM_FIELDS &&
> +		    (value & ~PIN_MUX_FIELD_MASK) == 0) {
> +			const int offset = field * PIN_MUX_FIELD_SIZE;
> +			const dv_reg *mux = pins[i].mux;
> +			const unsigned int mask = PIN_MUX_FIELD_MASK << offset;
> +
> +			value <<= offset;
> +			writel(value | (readl(mux) & (~mask)), mux);
> +		} else {
> +			return -1;
> +		}
> +	}
> +
> +	return 0;
> +}
> diff --git a/board/davinci/common/misc.h b/board/davinci/common/misc.h
> index dc3cc41..f6d8b1b 100644
> --- a/board/davinci/common/misc.h
> +++ b/board/davinci/common/misc.h
> @@ -22,8 +22,20 @@
>  #ifndef __MISC_H
>  #define __MISC_H
>  
> +/* pin muxer definitions */
> +#define PIN_MUX_NUM_FIELDS	8	/* Per register */
> +#define PIN_MUX_FIELD_SIZE	4	/* n in bits */
> +#define PIN_MUX_FIELD_MASK	((1 << PIN_MUX_FIELD_SIZE) - 1)
> +
> +/* pin definition */
> +struct pinmux_config {
> +	dv_reg		*mux;		/* Address of mux register */
> +	unsigned char	value;		/* Value to set in field */
> +	unsigned char	field;		/* field number */
> +};
>  
>  int dvevm_read_mac_address(uint8_t *buf);
>  void dv_configure_mac_address(uint8_t *rom_enetaddr);
> +int davinci_configure_pin_mux(const struct pinmux_config *pins, int n_pins);
>  
>  #endif /* __MISC_H */
> 
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