linux-imx

/*

 * SPEAr platform SPI chipselect abstraction over gpiolib

 *

 * Copyright (C) 2012 ST Microelectronics

 * Shiraz Hashim <shiraz.linux.kernel@gmail.com>

 *

 * This file is licensed under the terms of the GNU General Public

 * License version 2. This program is licensed "as is" without any

 * warranty of any kind, whether express or implied.

 */

​

#include <linux/err.h>

#include <linux/gpio/driver.h>

#include <linux/io.h>

#include <linux/init.h>

#include <linux/of.h>

#include <linux/platform_device.h>

#include <linux/types.h>

​

/* maximum chipselects */

#define NUM_OF_GPIO 4

​

/*

 * Provision is available on some SPEAr SoCs to control ARM PL022 spi cs

 * through system registers. This register lies outside spi (pl022)

 * address space into system registers.

 *

 * It provides control for spi chip select lines so that any chipselect

 * (out of 4 possible chipselects in pl022) can be made low to select

 * the particular slave.

 */

​

/**

 * struct spear_spics - represents spi chip select control

 * @base: base address

 * @perip_cfg: configuration register

 * @sw_enable_bit: bit to enable s/w control over chipselects

 * @cs_value_bit: bit to program high or low chipselect

 * @cs_enable_mask: mask to select bits required to select chipselect

 * @cs_enable_shift: bit pos of cs_enable_mask

 * @use_count: use count of a spi controller cs lines

 * @last_off: stores last offset caller of set_value()

 * @chip: gpio_chip abstraction

 */

struct spear_spics {

    void __iomem        *base;

    u32         perip_cfg;

    u32         sw_enable_bit;

    u32         cs_value_bit;

    u32         cs_enable_mask;

    u32         cs_enable_shift;

    unsigned long       use_count;

    int         last_off;

    struct gpio_chip    chip;

};

​

/* gpio framework specific routines */

static int spics_get_value(struct gpio_chip *chip, unsigned offset)

{

    return -ENXIO;

}

​

static void spics_set_value(struct gpio_chip *chip, unsigned offset, int value)