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mpc85xx: Add inline GPIO acessor functions

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To ease the implementation of other MPC85xx board ports, several common
GPIO helpers are added to <asm/mpc85xx_gpio.h>.

Since each of these compiles to no more than 4-5 instructions it would
be very inefficient to call them out of line, therefore we put them
entirely in the header file.

The HWW-1U-1A board port which these were written for strongly prefers
to set multiple GPIOs as a single batch operation, so the API is
designed around that basis.

To assist other board ports, a small set of wrappers are used which
provides a standard gpio_request() interface around the MPC85xx-specific
functions.  This can be enabled with CONFIG_MPC85XX_GENERIC_GPIO

Signed-off-by: Kyle Moffett <Kyle.D.Moffett@boeing.com>
Cc: Andy Fleming <afleming@gmail.com>
Cc: Peter Tyser <ptyser@xes-inc.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
This commit is contained in:
Kyle Moffett 2011-10-19 14:58:15 -04:00 committed by Kumar Gala
parent a836626cc4
commit 710308ee18
1 changed files with 123 additions and 0 deletions
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123
arch/powerpc/include/asm/mpc85xx_gpio.h Normal file
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/*
* Copyright 2010 eXMeritus, A Boeing Company
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
#ifndef POWERPC_ASM_MPC85XX_GPIO_H_
#define POWERPC_ASM_MPC85XX_GPIO_H_
# include <asm/immap_85xx.h>
/*
* The following internal functions are an MPC85XX-specific GPIO API which
* allows setting and querying multiple GPIOs in a single operation.
*
* All of these look relatively large, but the arguments are almost always
* constants, so they compile down to just a few instructions and a
* memory-mapped IO operation or two.
*/
static inline void mpc85xx_gpio_set(unsigned int mask,
unsigned int dir, unsigned int val)
{
ccsr_gpio_t *gpio = (void *)(CONFIG_SYS_MPC85xx_GPIO_ADDR + 0xc00);
/* First mask off the unwanted parts of "dir" and "val" */
dir &= mask;
val &= mask;
/* Now read in the values we're supposed to preserve */
dir |= (in_be32(&gpio->gpdir) & ~mask);
val |= (in_be32(&gpio->gpdat) & ~mask);
/*
* Poke the new output values first, then set the direction. This
* helps to avoid transient data when switching from input to output
* and vice versa.
*/
out_be32(&gpio->gpdat, val);
out_be32(&gpio->gpdir, dir);
}
static inline void mpc85xx_gpio_set_in(unsigned int gpios)
{
mpc85xx_gpio_set(gpios, 0x00000000, 0x00000000);
}
static inline void mpc85xx_gpio_set_low(unsigned int gpios)
{
mpc85xx_gpio_set(gpios, 0xFFFFFFFF, 0x00000000);
}
static inline void mpc85xx_gpio_set_high(unsigned int gpios)
{
mpc85xx_gpio_set(gpios, 0xFFFFFFFF, 0xFFFFFFFF);
}
static inline unsigned int mpc85xx_gpio_get(unsigned int mask)
{
ccsr_gpio_t *gpio = (void *)(CONFIG_SYS_MPC85xx_GPIO_ADDR + 0xc00);
/* Read the requested values */
return in_be32(&gpio->gpdat) & mask;
}
/*
* These implement the generic Linux GPIO API on top of the other functions
* in this header.
*/
static inline int gpio_request(unsigned gpio, const char *label)
{
/* Compatibility shim */
return 0;
}
static inline void gpio_free(unsigned gpio)
{
/* Compatibility shim */
}
static inline int gpio_direction_input(unsigned gpio)
{
mpc85xx_gpio_set_in(1U << gpio);
return 0;
}
static inline int gpio_direction_output(unsigned gpio, int value)
{
mpc85xx_gpio_set_low(1U << gpio);
return 0;
}
static inline int gpio_get_value(unsigned gpio)
{
return !!mpc85xx_gpio_get(1U << gpio);
}
static inline void gpio_set_value(unsigned gpio, int value)
{
if (value)
mpc85xx_gpio_set_high(1U << gpio);
else
mpc85xx_gpio_set_low(1U << gpio);
}
static inline int gpio_is_valid(int gpio)
{
return (gpio >= 0) && (gpio < 32);
}
#endif /* not POWERPC_ASM_MPC85XX_GPIO_H_ */