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-rw-r--r--arch/arm/mach-mx51/sdram_autogating.c164
1 files changed, 164 insertions, 0 deletions
diff --git a/arch/arm/mach-mx51/sdram_autogating.c b/arch/arm/mach-mx51/sdram_autogating.c
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+++ b/arch/arm/mach-mx51/sdram_autogating.c
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+/*
+ * Copyright 2009 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 <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/mxc_dvfs.h>
+#include "crm_regs.h"
+
+int sdram_autogating_is_active;
+static struct device *sdram_autogating_dev;
+#define M4IF_CNTL_REG0 0x8c
+#define M4IF_CNTL_REG1 0x90
+
+void enable_sdram_autogating(void);
+void disable_sdram_autogating(void);
+
+void enable_sdram_autogating()
+{
+ u32 reg;
+
+ /* Set the Fast arbitration Power saving timer */
+ reg = __raw_readl((IO_ADDRESS(M4IF_BASE_ADDR) + M4IF_CNTL_REG1));
+ reg &= ~0xFF;
+ reg |= 0x09;
+ __raw_writel(reg, (IO_ADDRESS(M4IF_BASE_ADDR) + 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((IO_ADDRESS(M4IF_BASE_ADDR) + M4IF_CNTL_REG0));
+ reg &= ~0x5;
+ __raw_writel(reg, (IO_ADDRESS(M4IF_BASE_ADDR) + M4IF_CNTL_REG0));
+
+ sdram_autogating_is_active = 1;
+}
+
+void disable_sdram_autogating()
+{
+ u32 reg;
+
+ reg = __raw_readl((IO_ADDRESS(M4IF_BASE_ADDR) + M4IF_CNTL_REG0));
+ reg |= 0x4;
+ __raw_writel(reg, (IO_ADDRESS(M4IF_BASE_ADDR) + M4IF_CNTL_REG0));
+ sdram_autogating_is_active = 0;
+}
+
+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_sdram_autogating();
+ else if (strstr(buf, "0") != NULL) {
+ if (sdram_autogating_is_active)
+ disable_sdram_autogating();
+ }
+ 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)
+{
+ int err = 0;
+
+ sdram_autogating_dev = &pdev->dev;
+
+ 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;
+ if (mxc_cpu_is_rev(CHIP_REV_3_0) >= 1)
+ enable_sdram_autogating();
+ 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");
+