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/*
* Copyright (C) 2009-2011 Freescale Semiconductor, Inc. All Rights Reserved.
*/
/*
* The code contained herein is licensed under the GNU General Public
* License. You may obtain a copy of the GNU General Public License
* Version 2 or later at the following locations:
*
* http://www.opensource.org/licenses/gpl-license.html
* http://www.gnu.org/copyleft/gpl.html
*/
/*!
* @file sdram_autogating.c
*
* @brief Enable auto clock gating of the EMI_FAST clock using M4IF.
*
* The APIs are for enabling and disabling automatic clock gating of EMI_FAST.
*
* @ingroup PM
*/
#include <linux/module.h>
#include <asm/io.h>
#include <linux/proc_fs.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/regulator/consumer.h>
#include <mach/hardware.h>
#include <mach/clock.h>
#include <mach/sdram_autogating.h>
#include "crm_regs.h"
static struct device *sdram_autogating_dev;
#define M4IF_CNTL_REG0 0x8c
#define M4IF_CNTL_REG1 0x90
/* Flag used to indicate if SDRAM M4IF autoclock gating feature is active. */
static int sdram_autogating_is_active;
static int sdram_autogating_paused;
static void __iomem *m4if_base;
void start_sdram_autogating(void);
void stop_sdram_autogating(void);
int sdram_autogating_active(void);
static void enable(void)
{
u32 reg;
/* Set the Fast arbitration Power saving timer */
reg = __raw_readl(m4if_base + M4IF_CNTL_REG1);
reg &= ~0xFF;
reg |= 0x09;
__raw_writel(reg, m4if_base + M4IF_CNTL_REG1);
/*Allow for automatic gating of the EMI internal clock.
* If this is done, emi_intr CCGR bits should be set to 11.
*/
reg = __raw_readl(m4if_base + M4IF_CNTL_REG0);
reg &= ~0x5;
__raw_writel(reg, m4if_base + M4IF_CNTL_REG0);
sdram_autogating_is_active = 1;
}
static void disable(void)
{
u32 reg;
reg = __raw_readl(m4if_base + M4IF_CNTL_REG0);
reg |= 0x4;
__raw_writel(reg, m4if_base + M4IF_CNTL_REG0);
sdram_autogating_is_active = 0;
}
int sdram_autogating_active()
{
return sdram_autogating_is_active;
}
void start_sdram_autogating()
{
if (cpu_is_mx50())
return;
if (sdram_autogating_paused) {
enable();
sdram_autogating_paused = 0;
}
}
void stop_sdram_autogating()
{
if (cpu_is_mx50())
return;
if (sdram_autogating_is_active) {
sdram_autogating_paused = 1;
disable();
}
}
static ssize_t sdram_autogating_enable_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
if (sdram_autogating_is_active)
return sprintf(buf,
"M4IF autoclock gating for EMI_FAST enabled\n");
else
return sprintf(buf,
"M4IF autoclock gating for EMI_FAST disabled\n");
}
static ssize_t sdram_autogating_enable_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t size)
{
if (strstr(buf, "1") != NULL)
enable();
else if (strstr(buf, "0") != NULL) {
if (sdram_autogating_is_active)
disable();
}
return size;
}
static DEVICE_ATTR(enable, 0644, sdram_autogating_enable_show,
sdram_autogating_enable_store);
/*!
* This is the probe routine for the auto clockgating of sdram driver.
*
* @param pdev The platform device structure
*
* @return The function returns 0 on success
*
*/
static int __devinit sdram_autogating_probe(struct platform_device *pdev)
{
struct resource *res;
int err = 0;
sdram_autogating_dev = &pdev->dev;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res) {
return -ENOMEM;
}
m4if_base = ioremap(res->start, res->end - res->start + 1);
err = sysfs_create_file(&sdram_autogating_dev->kobj,
&dev_attr_enable.attr);
if (err) {
printk(KERN_ERR
"Unable to register sysdev entry for sdram_autogating");
return err;
}
sdram_autogating_is_active = 0;
return 0;
}
static struct platform_driver sdram_autogating_driver = {
.driver = {
.name = "sdram_autogating",
},
.probe = sdram_autogating_probe,
};
/*!
* Initialise the sdram_autogating_driver.
*
* @return The function always returns 0.
*/
static int __init sdram_autogating_init(void)
{
if (platform_driver_register(&sdram_autogating_driver) != 0) {
printk(KERN_ERR "sdram_autogating_driver register failed\n");
return -ENODEV;
}
printk(KERN_INFO "sdram autogating driver module loaded\n");
return 0;
}
static void __exit sdram_autogating_cleanup(void)
{
sysfs_remove_file(&sdram_autogating_dev->kobj, &dev_attr_enable.attr);
/* Unregister the device structure */
platform_driver_unregister(&sdram_autogating_driver);
}
module_init(sdram_autogating_init);
module_exit(sdram_autogating_cleanup);
MODULE_AUTHOR("Freescale Semiconductor, Inc.");
MODULE_DESCRIPTION("sdram_autogating driver");
MODULE_LICENSE("GPL");
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