ENGR00132712-1: Add ZQ calibration support

Add ZQ calibration support

Signed-off-by: Terry Lv <r65388@freescale.com>

4 files changed, 298 insertions, 0 deletions

diff --git a/arch/arm/plat-mxc/Kconfig b/arch/arm/plat-mxc/Kconfig
index 27e8dd05e9c6..926379f3f99f 100644
--- a/arch/arm/plat-mxc/Kconfig
+++ b/arch/arm/plat-mxc/Kconfig
@@ -207,4 +207,10 @@ config MXC_DVFS_PER
 	help
 	   Select this if you want to enable HW supported peripheral frequency scaling.
 
+config MXC_ZQ_CALIBRATION
+	bool "Enable mDDR/LPDDR2/DDR2 ZQ calibration"
+	depends on ARCH_MX50
+	help
+	   Select this if you're sure it's needed.
+
 endif
diff --git a/arch/arm/plat-mxc/Makefile b/arch/arm/plat-mxc/Makefile
index 0c07107304af..c935fd46741b 100644
--- a/arch/arm/plat-mxc/Makefile
+++ b/arch/arm/plat-mxc/Makefile
@@ -49,4 +49,7 @@ obj-$(CONFIG_MC13783_MXC) += mc13783_xc.o
 obj-$(CONFIG_UTMI_MXC) += utmixc.o
 obj-$(CONFIG_USB) += serialxc.o
 
+# ZQ calibration
+obj-$(CONFIG_MXC_ZQ_CALIBRATION) += zq_calib.o
+
 obj-y += devices/
diff --git a/arch/arm/plat-mxc/include/mach/mx5x.h b/arch/arm/plat-mxc/include/mach/mx5x.h
index f407b024eaaf..8d053e0a43f4 100644
--- a/arch/arm/plat-mxc/include/mach/mx5x.h
+++ b/arch/arm/plat-mxc/include/mach/mx5x.h
@@ -151,6 +151,10 @@
 #define DATABAHN_CTL_REG43			0xac
 #define DATABAHN_CTL_REG55			0xdc
 #define DATABAHN_CTL_REG63			0xFC
+#define DATABAHN_CTL_REG73			0x124
+#define DATABAHN_CTL_REG74			0x128
+#define DATABAHN_CTL_REG75			0x12C
+#define DATABAHN_CTL_REG83			0x14C
 #define LOWPOWER_CONTROL_MASK	 	0x1F
 #define LOWPOWER_AUTOENABLE_MASK 		0x1F
 #define LOWPOWER_EXTERNAL_CNT_MASK		(0xFFFF << 16)
diff --git a/arch/arm/plat-mxc/zq_calib.c b/arch/arm/plat-mxc/zq_calib.c
new file mode 100644
index 000000000000..3f7f19f7a3b0
--- /dev/null
+++ b/arch/arm/plat-mxc/zq_calib.c
@@ -0,0 +1,285 @@
+/*
+ * Copyright (C) 2010 Freescale Semiconductor, Inc. All Rights Reserved.
+ */
+
+/*
+ * 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <linux/workqueue.h>
+
+#include <mach/hardware.h>
+
+/* 5 mins */
+#define ZQ_INTERVAL	(5 * 60 * 1000)
+
+static void mxc_zq_main(void);
+
+/* Use workqueue */
+static struct workqueue_struct *zq_queue;
+static DEFINE_SPINLOCK(zq_lock);
+static DECLARE_DELAYED_WORK(zq_work, mxc_zq_main);
+
+extern void __iomem *databahn_base;
+
+#define DATABAHN_REG_ZQ_HW_CFG		DATABAHN_CTL_REG73
+#define DATABAHN_REG_ZQ_SW_CFG1		DATABAHN_CTL_REG74
+#define DATABAHN_REG_ZQ_SW_CFG2		DATABAHN_CTL_REG75
+#define DATABAHN_REG_ZQ_STATUS		DATABAHN_CTL_REG83
+
+/*!
+ * MXC ZQ interface - Compare PU vs the External Resistor (240/300 ohm)
+ *
+ * @param pu	u32
+ * @param pd	u32
+ *
+ * @return	Return compare result.
+ */
+static u32 mxc_zq_pu_compare(u32 pu, u32 pd)
+{
+	u32 data;
+
+	/* set PU & PD value */
+	data = (pd << 24) | (pu << 16);
+	__raw_writel(data, databahn_base + DATABAHN_REG_ZQ_SW_CFG1);
+	/*
+	 * set PU+1 & PD+1 value
+	 * when pu=0x1F, set (pu+1) = 0x1F
+	 */
+	data = ((pd + 1) << 8) | (pu + 1);
+	__raw_writel(data, databahn_base + DATABAHN_REG_ZQ_SW_CFG2);
+	/*
+	 * Enable the ZQ comparator,
+	 * need 300ns to complete a ZQ comparison
+	 */
+	__raw_writel(1 << 16, databahn_base + DATABAHN_REG_ZQ_HW_CFG);
+	/* TODO:  wait 300ns till comparator output stable */
+	ndelay(300);
+	/* read status bit[0] */
+	data = __raw_readl(databahn_base + DATABAHN_REG_ZQ_STATUS);
+	data &= 0x1;
+	/* Disable the ZQ comparator to save power */
+	__raw_writel(0, databahn_base + DATABAHN_REG_ZQ_HW_CFG);
+	return data;
+}
+
+/*!
+ * MXC ZQ interface - Compare PU vs PD
+ *
+ * @param pu	u32
+ * @param pd	u32
+ *
+ * @return	Return compare result.
+ */
+static u32 mxc_zq_pd_compare(u32 pu, u32 pd)
+{
+	u32 data;
+
+	/* set bit[4]=1, select PU/PD comparison */
+	/* PD range: 0~0xE  (0xF has problem, drop it) */
+	data = (pd << 24) | (pu << 16) | (1 << 4);
+	__raw_writel(data, databahn_base + DATABAHN_REG_ZQ_SW_CFG1);
+	/* when pu=0x1F, set (pu+1) = 0x1F */
+	data = ((pd + 1) << 8) | (pu + 1);
+	__raw_writel(data, databahn_base + DATABAHN_REG_ZQ_SW_CFG2);
+	/*
+	 * Enable the ZQ comparator,
+	 * need 300ns to complete a ZQ comparison
+	 */
+	__raw_writel(1 << 16, databahn_base + DATABAHN_REG_ZQ_HW_CFG);
+	/* TODO:  wait 300ns till comparator output stable */
+	ndelay(300);
+	/* read status bit[0] */
+	data = __raw_readl(databahn_base + DATABAHN_REG_ZQ_STATUS);
+	data &= 0x1;
+	/* Disable the ZQ comparator to save power */
+	__raw_writel(0, databahn_base + DATABAHN_REG_ZQ_HW_CFG);
+	return data;
+}
+
+/*!
+ * MXC ZQ interface - Do a full range search of PU to
+ * 			match the external resistor
+ *
+ * @param start	u32
+ *
+ * @return	Return pu.
+ */
+static u32 mxc_zq_pu_calib(u32 start)
+{
+	u32 i;
+	u32 data;
+	u32 zq_pu_val = 0;
+
+	/*
+	 * Compare PU from 0 to 0x1F
+	 * data is the result of the comparator
+	 * the result sequence looks like:
+	 * 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
+	 * Take the First "1" the sequence for PU
+	 */
+	for (i = start; i < 32; ++i) {
+		data = mxc_zq_pu_compare(i, 0);
+		if (data) {
+			zq_pu_val = i;
+			break;
+		}
+	}
+
+	return zq_pu_val;
+}
+
+/*!
+ * MXC ZQ interface - Do a full range search of PD to match
+ * 			the PU get from za_pu_calib()
+ *
+ * @param start	u32
+ * @param pu	u32
+ *
+ * @return	Return pd.
+ */
+static s32 mxc_zq_pd_calib(u32 start, u32 pu)
+{
+	u32 i;
+	u32 data;
+	u32 zq_pd_val = 0;
+
+	/*
+	 * Compare PD from 0 to 0x0E  (please ignore 0x0F)
+	 * data is the result of the comparator
+	 * the result sequence looks like:
+	 * 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0
+	 * Take the Last "1" in the sequence for PD
+	 */
+	for (i = start; i < 15; ++i) {
+		data = mxc_zq_pd_compare(pu, i);
+		if (!data && (i > 0)) {
+			zq_pd_val = i - 1;
+			break;
+		}
+	}
+
+	return zq_pd_val;
+}
+
+/*!
+ * MXC ZQ interface - Load the PU/PD value to the ZQ buffers by hardware
+ *
+ * @param pu	u32
+ * @param pd	u32
+ */
+static void mxc_zq_hw_load(u32 pu, u32 pd)
+{
+	u32 data;
+	/*
+	 * The PU/PD values stored in register
+	 * DATABAHN_REG_ZQ_SW_CFG1/2 would be loaded
+	 */
+	data = (pd << 24) | (pu << 16);
+	__raw_writel(data, databahn_base + DATABAHN_REG_ZQ_SW_CFG1);
+	data = ((pd + 1) << 8) | (pu + 1);
+	__raw_writel(data, databahn_base + DATABAHN_REG_ZQ_SW_CFG2);
+
+	/*
+	 * bit[0]: enable hardware load
+	 * bit[4]: trigger a hardware load.
+	 *
+	 * When the posedge of bit[4] detected, hardware trigger a load.
+	 */
+	__raw_writel(0x11, databahn_base + DATABAHN_REG_ZQ_HW_CFG);
+	/* clear bit[4] for next load */
+	__raw_writel(0x01, databahn_base + DATABAHN_REG_ZQ_HW_CFG);
+}
+
+/*!
+ * MXC ZQ interface - Load the PU/PD value to the ZQ buffers by software
+ *
+ * @param pu	u32
+ * @param pd	u32
+ */
+
+static void mxc_zq_sw_load(u32 pu, u32 pd)
+{
+	u32 data;
+
+	/*
+	 * The PU/PD values stored in register
+	 * DATABAHN_REG_ZQ_SW_CFG1/2 would be loaded.
+	 * */
+	data = (pd << 24) | (pu << 16);
+	__raw_writel(data, databahn_base + DATABAHN_REG_ZQ_SW_CFG1);
+	data = ((pd + 1) << 8) | (pu + 1);
+	__raw_writel(data, databahn_base + DATABAHN_REG_ZQ_SW_CFG2);
+
+	/*
+	 * bit[21]: select software load
+	 * bit[20]: enable software load
+	 */
+	__raw_writel(0x3 << 20, databahn_base + DATABAHN_REG_ZQ_HW_CFG);
+	/* clear for next load */
+	__raw_writel(0x0, databahn_base + DATABAHN_REG_ZQ_HW_CFG);
+}
+
+/*!
+ * MXC ZQ interface - PU/PD calib function
+ * This function Do a complete PU/PD calib and loading process.
+ */
+static void mxc_zq_main(void)
+{
+	u32 pu, pd;
+
+	spin_lock(&zq_lock);
+	/* Search pu value start from 0 */
+	pu = mxc_zq_pu_calib(0);
+	/* Search pd value start from 0 */
+	pd = mxc_zq_pd_calib(0, pu);
+	mxc_zq_hw_load(pu, pd);
+	/* or do software load alternatively */
+	/* zq_sw_load(pu, pd); */
+	spin_unlock(&zq_lock);
+
+	queue_delayed_work(zq_queue, &zq_work, msecs_to_jiffies(ZQ_INTERVAL));
+}
+
+static int __init mxc_zq_calib_init(void)
+{
+	zq_queue = create_singlethread_workqueue("zq_calib");;
+	if (!zq_queue)
+		return -ENOMEM;
+
+	mxc_zq_main();
+
+	return 0;
+}
+
+static void __exit mxc_zq_calib_exit(void)
+{
+	cancel_delayed_work(&zq_work);
+	flush_workqueue(zq_queue);
+	destroy_workqueue(zq_queue);
+}
+
+module_init(mxc_zq_calib_init);
+module_exit(mxc_zq_calib_exit);
+
+MODULE_AUTHOR("Freescale Semiconductor, Inc.");
+MODULE_DESCRIPTION("MXC ZQ Calibration driver");
+MODULE_LICENSE("GPL");