From 4242860c4fc7ce2f17b7a90411c1f2712ccef03c Mon Sep 17 00:00:00 2001
From: Robert Nelson <robertcnelson@gmail.com>
Date: Wed, 2 Nov 2016 11:11:27 -0500
Subject: [PATCH] tieqep: forward port of Nathaniel Lewis eQEP driver

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>
---
 arch/arm/boot/dts/am33xx.dtsi |  31 ++
 drivers/misc/Kconfig          |  11 +
 drivers/misc/Makefile         |   1 +
 drivers/misc/tieqep.c         | 738 ++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 781 insertions(+)
 create mode 100644 drivers/misc/tieqep.c

diff --git a/arch/arm/boot/dts/am33xx.dtsi b/arch/arm/boot/dts/am33xx.dtsi
index 771fc0a..20ccf52 100644
--- a/arch/arm/boot/dts/am33xx.dtsi
+++ b/arch/arm/boot/dts/am33xx.dtsi
@@ -701,6 +701,16 @@
 				status = "disabled";
 			};
 
+			eqep0: eqep@0x48300180 {
+				compatible = "ti,am33xx-eqep";
+				reg = <0x48300180 0x80>;
+				clocks = <&l4ls_gclk>;
+				clock-names = "fck";
+				interrupt-parent = <&intc>;
+				interrupts = <79>;
+				status = "disabled";
+			};
+
 			ehrpwm0: pwm@48300200 {
 				compatible = "ti,am3352-ehrpwm",
 					     "ti,am33xx-ehrpwm";
@@ -735,6 +745,17 @@
 				status = "disabled";
 			};
 
+
+			eqep1: eqep@0x48302180 {
+				compatible = "ti,am33xx-eqep";
+				reg = <0x48302180 0x80>;
+				clocks = <&l4ls_gclk>;
+				clock-names = "fck";
+				interrupt-parent = <&intc>;
+				interrupts = <88>;
+				status = "disabled";
+			};
+
 			ehrpwm1: pwm@48302200 {
 				compatible = "ti,am3352-ehrpwm",
 					     "ti,am33xx-ehrpwm";
@@ -769,6 +790,16 @@
 				status = "disabled";
 			};
 
+			eqep2: eqep@0x48304180 {
+				compatible = "ti,am33xx-eqep";
+				reg = <0x48304180 0x80>;
+				clocks = <&l4ls_gclk>;
+				clock-names = "fck";
+				interrupt-parent = <&intc>;
+				interrupts = <89>;
+				status = "disabled";
+			};
+
 			ehrpwm2: pwm@48304200 {
 				compatible = "ti,am3352-ehrpwm",
 					     "ti,am33xx-ehrpwm";
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index e3c6a92..b444d1db 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -785,6 +785,17 @@ config DEV_OVERLAYMGR
 	  Say Y here to include support for the automagical dev
 	  overlay manager.
 
+config TIEQEP
+	tristate "EQEP Hardware quadrature encoder controller"
+	depends on SOC_AM33XX
+	select PWM_TIPWMSS
+	help
+	  Driver support for the EQEP quadrature encoder controller AM33XX
+	  TI SOC
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called tieqep.
+
 source "drivers/misc/c2port/Kconfig"
 source "drivers/misc/eeprom/Kconfig"
 source "drivers/misc/cb710/Kconfig"
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 9df0a01..a84dde4 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -53,6 +53,7 @@ obj-$(CONFIG_ECHO)		+= echo/
 obj-$(CONFIG_VEXPRESS_SYSCFG)	+= vexpress-syscfg.o
 obj-$(CONFIG_CXL_BASE)		+= cxl/
 obj-$(CONFIG_PANEL)             += panel.o
+obj-$(CONFIG_TIEQEP)		+= tieqep.o
 obj-$(CONFIG_BONE_CAPEMGR)	+= bone_capemgr.o
 obj-$(CONFIG_DEV_OVERLAYMGR)	+= devovmgr.o
 
diff --git a/drivers/misc/tieqep.c b/drivers/misc/tieqep.c
new file mode 100644
index 0000000..d2628847
--- /dev/null
+++ b/drivers/misc/tieqep.c
@@ -0,0 +1,738 @@
+/*
+ * TI eQEP driver for AM33xx devices
+ *
+ * Copyright (C) 2013 Nathaniel R. Lewis - http://teknoman117.wordpress.com/
+ * Copyright (C) 2015 SoftPLC Corporation, Dick Hollenbeck <dick@softplc.com>
+ *
+ * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ *
+ * sysfs entries
+ *	 - position = absolute - current position; relative - last latched value
+ *	 - mode => 0 - absolute; 1 - relative
+ *	 - period => sampling period for the hardware
+ *	 - enable => 0 - eQEP disabled, 1 - eQEP enabled
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/pm_runtime.h>
+#include <linux/of_device.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/input.h>
+
+/* eQEP register offsets from its base IO address */
+#define QPOSCNT		0x0000
+#define QPOSINIT	0x0004
+#define QPOSMAX		0x0008
+#define QPOSCMP		0x000C
+#define QPOSILAT	0x0010
+#define QPOSSLAT	0x0014
+#define QPOSLAT		0x0018
+#define QUTMR		0x001C
+#define QUPRD		0x0020
+#define QWDTMR		0x0024
+#define QWDPRD		0x0026
+#define QDECCTL		0x0028
+#define QEPCTL		0x002A
+#define QCAPCTL		0x002C
+#define QPOSCTL		0x002E
+#define QEINT		0x0030
+#define QFLG		0x0032
+#define QCLR		0x0034
+#define QFRC		0x0036
+#define QEPSTS		0x0038
+#define QCTMR		0x003A
+#define QCPRD		0x003C
+#define QCTMRLAT	0x003E
+#define QCPRDLAT	0x0040
+#define QREVID		0x005C
+
+#if 0	/* if you wanted another way to modify IP registers... */
+typedef volatile u32	REG32;
+typedef volatile u16	REG16;
+struct EQEP_REGS {
+	REG32	q_poscnt;		/*	0x00	position counter */
+	REG32	q_posinit;		/*	0x04	position counter initialization */
+	REG32	q_posmax;		/*	0x08	maximum position count */
+	REG32	q_poscmp;		/*	0x0C	position compare */
+	REG32	q_posilat;		/*	0x10	index position latch */
+	REG32	q_posslat;		/*	0x14	strobe position latch */
+	REG32	q_poslat;		/*	0x18	position counter latch */
+	REG32	q_utmr;			/*	0x1C	unit timer */
+	REG32	q_uprd;			/*	0x20	unit period */
+	REG16	q_wdtmr;		/*	0x24	watchdog timer */
+	REG16	q_wdprd;		/*	0x26	watchdog period */
+	REG16	q_decctl;		/*	0x28	decoder control */
+	REG16	q_epctl;		/*	0x2A	control register */
+	REG16	q_capctl;		/*	0x2C	capture control */
+	REG16	q_posctl;		/*	0x2E	position compare control */
+	REG16	q_eint;			/*	0x30	interrupt enable */
+	REG16	q_flg;			/*	0x32	interrupt flag */
+	REG16	q_clr;			/*	0x34	interrupt clear */
+	REG16	q_frc;			/*	0x36	interrupt force */
+	REG16	q_epsts;		/*	0x38	status */
+	REG16	q_ctmr;			/*	0x3A	capture timer */
+	REG16	q_cprd;			/*	0x3C	capture period */
+	REG16	q_ctmrlat;		/*	0x3E	capture timer latch */
+	REG16	q_prdlat;		/*	0x40	capture period latch */
+	char	q_fill1[0x5c-0x40];
+	REG32	q_revid;		/*	0x5C	revision id */
+};
+#endif
+
+
+/* Bits for the QDECTL register */
+#define QSRC1		(1 << 15)
+#define QSRC0		(1 << 14)
+#define SOEN		(1 << 13)
+#define SPSEL		(1 << 12)
+#define XCR		(1 << 11)
+#define SWAP		(1 << 10)
+#define IGATE		(1 << 9)
+#define QAP		(1 << 8)
+#define QBP		(1 << 7)
+#define QIP		(1 << 6)
+#define QSP		(1 << 5)
+
+/* Bits for the QEPCTL register */
+#define FREESOFT1	(1 << 15)
+#define FREESOFT0	(1 << 14)
+#define PCRM1		(1 << 13)
+#define PCRM0		(1 << 12)
+#define SEI1		(1 << 11)
+#define SEI0		(1 << 10)
+#define IEI1		(1 << 9)
+#define IEI0		(1 << 8)
+#define SWI		(1 << 7)
+#define SEL		(1 << 6)
+#define IEL1		(1 << 5)
+#define IEL0		(1 << 4)
+#define PHEN		(1 << 3)
+#define QCLM		(1 << 2)
+#define UTE		(1 << 1)
+#define WDE		(1 << 0)
+
+/* Bits for the QCAPCTL register */
+#define CEN		(1 << 15)
+#define CCPS2		(1 << 6)
+#define CCPS0		(1 << 5)
+#define CCPS1		(1 << 4)
+#define UPPS3		(1 << 3)
+#define UPPS2		(1 << 2)
+#define UPPS1		(1 << 1)
+#define UPPS0		(1 << 0)
+
+/* Bits for the QPOSCTL register */
+#define PCSHDW		(1 << 15)
+#define PCLOAD		(1 << 14)
+#define PCPOL		(1 << 13)
+#define PCE		(1 << 12)
+#define PCSPW11		(1 << 11)
+#define PCSPW10		(1 << 10)
+#define PCSPW9		(1 << 9)
+#define PCSPW8		(1 << 8)
+#define PCSPW7		(1 << 7)
+#define PCSPW6		(1 << 6)
+#define PCSPW5		(1 << 5)
+#define PCSPW4		(1 << 4)
+#define PCSPW3		(1 << 3)
+#define PCSPW2		(1 << 2)
+#define PCSPW1		(1 << 1)
+#define PCSPW0		(1 << 0)
+
+/* Bits for the interrupt registers */
+#define EQEP_INTERRUPT_MASK	0x0FFF
+#define UTOF			(1 << 11)
+
+/* Bits to control the clock in the PWMSS subsystem */
+#define PWMSS_EQEPCLK_EN	BIT(4)
+#define PWMSS_EQEPCLK_STOP_REQ	BIT(5)
+#define PWMSS_EQEPCLK_EN_ACK	BIT(4)
+
+/*
+ * Modes for the eQEP unit
+ *	Absolute - the position entry represents the current position of the encoder.
+ *		   Poll this value and it will be notified every period nanoseconds
+ *	Relative - the position entry represents the last latched position of the encoder
+ *		   This value is latched every period nanoseconds and the internal counter
+ *		   is subsequenty reset
+ */
+#define TIEQEP_MODE_ABSOLUTE	0
+#define TIEQEP_MODE_RELATIVE	1
+
+/* Structure defining the characteristics of the eQEP unit */
+struct eqep_chip
+{
+	/* Platform device for this eQEP unit */
+	struct platform_device *pdev;
+
+	/* Pointer to the base of the memory of the eQEP unit */
+	void __iomem	*mmio_base;
+
+	/* SYSCLKOUT to the eQEP unit */
+	u32		clk_rate;
+
+	/* IRQ for the eQEP unit */
+	u16		irq;
+
+	/* Mode of the eQEP unit */
+	u8		op_mode;
+
+	/* work stuct for the notify userspace work */
+	struct work_struct notify_work;
+
+	/* Backup for driver suspension */
+	u16		prior_qepctl;
+	u16		prior_qeint;
+};
+
+/* Notify userspace work */
+static void notify_handler(struct work_struct *work)
+{
+	/* Get a reference to the eQEP driver */
+	struct eqep_chip *eqep = container_of(work, struct eqep_chip, notify_work);
+
+	/* Notify the userspace */
+	sysfs_notify(&eqep->pdev->dev.kobj, NULL, "position");
+}
+
+/* eQEP Interrupt handler */
+static irqreturn_t eqep_irq_handler(int irq, void *dev_id)
+{
+	/* Get the instance information */
+	struct platform_device	*pdev = dev_id;
+	struct eqep_chip	*eqep = platform_get_drvdata(pdev);
+
+	/* Get the interrupt flags */
+	u16 iflags = readw(eqep->mmio_base + QFLG) & EQEP_INTERRUPT_MASK;
+
+	/* Check the interrupt source(s) */
+	if (iflags & UTOF) {
+		/* Handle the unit timer overflow interrupt by notifying any potential pollers */
+		schedule_work(&eqep->notify_work);
+	}
+
+	/* Clear interrupt flags (write back triggered flags to the clear register) */
+	writew(iflags, eqep->mmio_base + QCLR);
+
+	/* Return that the IRQ was handled successfully */
+	return IRQ_HANDLED;
+}
+
+/* Function to read whether the eQEP unit is enabled or disabled */
+static ssize_t eqep_get_enabled(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	/* Get the instance structure */
+	struct eqep_chip *eqep = dev_get_drvdata(dev);
+
+	/* Read the qep control register and mask all but the enabled bit */
+	u16 enabled = readw(eqep->mmio_base + QEPCTL) & PHEN;
+
+	/* Return the target in string format */
+	return sprintf(buf, "%u\n", (enabled) ? 1 : 0);
+}
+
+/* Function to set if the eQEP is enabled */
+static ssize_t eqep_set_enabled(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
+{
+	/* Get the instance structure */
+	int	rc;
+	u16	val;
+	u8	enabled;
+	struct eqep_chip *eqep = dev_get_drvdata(dev);
+
+	/* Convert the input string to an 8 bit uint */
+	if ((rc = kstrtou8(buf, 0, &enabled)))
+		return rc;
+
+	/* Get the existing state of QEPCTL */
+	val = readw(eqep->mmio_base + QEPCTL);
+
+	/* If we passed a number that is not 0, enable the eQEP */
+	if (enabled)
+		/* Enable the eQEP (Set PHEN in QEPCTL) */
+		val |= PHEN;
+	else
+		/* Disable the eQEP (Clear PHEN in QEPCTL) */
+		val &= ~PHEN;
+
+	/* Write flags back to control register */
+	writew(val, eqep->mmio_base + QEPCTL);
+
+	/* Return buffer length consumed (all) */
+	return count;
+}
+
+/* Function to read the current position of the eQEP */
+static ssize_t eqep_get_position(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct eqep_chip *eqep = dev_get_drvdata(dev);
+
+	s32 position = 0;
+
+	if (eqep->op_mode == TIEQEP_MODE_ABSOLUTE) {
+		position = readl(eqep->mmio_base + QPOSCNT);
+	} else if (eqep->op_mode == TIEQEP_MODE_RELATIVE) {
+		/* in relative mode, use the last latched value of the eQEP hardware */
+		position = readl(eqep->mmio_base + QPOSLAT);
+		dev_dbg(dev, "get_position:0x%08x\n", position);
+	}
+
+	return sprintf(buf, "%d\n", position);
+}
+
+/* Function to set the position of the eQEP hardware */
+static ssize_t eqep_set_position(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
+{
+	int rc;
+	s32 position;
+	struct eqep_chip *eqep = dev_get_drvdata(dev);
+
+	if ((rc = kstrtos32(buf, 0, &position)))
+		return rc;
+
+	/*
+	 * If we are in absolute mode, set the position of the encoder,
+	 * discard relative mode because thats pointless
+	 */
+	if (eqep->op_mode == TIEQEP_MODE_ABSOLUTE) {
+		/* If absolute mode, set the current value of the eQEP hardware */
+		writel(position, eqep->mmio_base + QPOSCNT);
+	}
+
+	/* Return buffer length consumed (all) */
+	return count;
+}
+
+/* Function to read the period of the unit time event timer */
+static ssize_t eqep_get_timer_period(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct eqep_chip *eqep = dev_get_drvdata(dev);
+	u64 period;
+
+	/* Convert from counts per interrupt back into period_ns */
+	period = readl(eqep->mmio_base + QUPRD);
+	period = period * NSEC_PER_SEC;
+	do_div(period, eqep->clk_rate);
+
+	/* Otherwise write out the data */
+	return sprintf(buf, "%llu\n", period);
+}
+
+/* Function to set the unit timer period.  0 = off, greater than zero sets the period */
+static ssize_t eqep_set_timer_period(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
+{
+	int	rc;
+	u16	tmp;
+	u64	period;
+
+	struct eqep_chip *eqep = dev_get_drvdata(dev);
+
+	if ((rc = kstrtou64(buf, 0, &period)))
+		return rc;
+
+	/* Disable the unit timer before modifying its period register */
+	tmp = readw(eqep->mmio_base + QEPCTL);
+	tmp &= ~(UTE | QCLM);
+	writew(tmp, eqep->mmio_base + QEPCTL);
+
+	/* Zero the unit timer counter register */
+	writel(0, eqep->mmio_base + QUTMR);
+
+	/* If the timer is enabled (a non-zero period has been passed) */
+	if (period) {
+		/* update the period */
+		period = period * eqep->clk_rate;
+		do_div(period, NSEC_PER_SEC);
+
+		dev_dbg(dev, "eqep_set_timer_period:%llu\n", period);
+
+		writel(period, eqep->mmio_base + QUPRD);
+
+		/* Enable unit timer, and latch QPOSLAT to QPOSCNT on timer expiration */
+		tmp |= UTE | QCLM;
+		writew(tmp, eqep->mmio_base + QEPCTL);
+	}
+
+	return count;
+}
+
+/* Function to read the mode of the eQEP hardware */
+static ssize_t eqep_get_mode(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct eqep_chip *eqep = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%u\n", eqep->op_mode);
+}
+
+/* Function to set the mode of the eQEP hardware */
+static ssize_t eqep_set_mode(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
+{
+	int 	rc;
+	u16 	val;
+	u8	tmp_mode;
+	struct eqep_chip *eqep = dev_get_drvdata(dev);
+
+	if ((rc = kstrtou8(buf, 0, &tmp_mode)))
+		return rc;
+
+	dev_dbg(dev, "eqep_set_mode:%d\n", tmp_mode);
+
+	val = readw(eqep->mmio_base + QEPCTL);
+
+	if (tmp_mode == TIEQEP_MODE_ABSOLUTE) {
+		/*
+		 * In absolute mode, don't reset the hardware based on time,
+		 * so disable the unit timer position reset (Set PCRM[1:0] = 0)
+		 */
+		val &= ~(PCRM1 | PCRM0);
+
+		eqep->op_mode = TIEQEP_MODE_ABSOLUTE;
+	} else if (tmp_mode == TIEQEP_MODE_RELATIVE) {
+		/*
+		 * In relative mode, latch the value of the eQEP hardware on the
+		 * overflow of the unit timer.	So enable the unit timer position reset
+		 * (Set PCRM[1:0] = 3)
+		 */
+		val |= PCRM1 | PCRM0;
+
+		eqep->op_mode = TIEQEP_MODE_RELATIVE;
+	}
+
+	writew(val, eqep->mmio_base + QEPCTL);
+
+	return count;
+}
+
+/* Bind read/write functions to sysfs entries */
+static DEVICE_ATTR(enabled,	0644, eqep_get_enabled,		eqep_set_enabled);
+static DEVICE_ATTR(position,	0644, eqep_get_position,	eqep_set_position);
+static DEVICE_ATTR(period,	0644, eqep_get_timer_period,	eqep_set_timer_period);
+static DEVICE_ATTR(mode,	0644, eqep_get_mode,		eqep_set_mode);
+
+/* Array holding all of the sysfs entries */
+static const struct attribute *eqep_attrs[] = {
+	&dev_attr_enabled.attr,
+	&dev_attr_position.attr,
+	&dev_attr_period.attr,
+	&dev_attr_mode.attr,
+	NULL,
+};
+
+/* Driver function group */
+static const struct attribute_group eqep_device_attr_group = {
+	.attrs = (struct attribute **) eqep_attrs,
+};
+
+/* Driver compatibility list */
+static struct of_device_id eqep_of_match[] =
+{
+	{ .compatible = "ti,am33xx-eqep" },
+	{ }
+};
+
+/* Register our compatibilities for device trees */
+MODULE_DEVICE_TABLE(of, eqep_of_match);
+
+/* Create an instance of the eQEP driver */
+static int eqep_probe(struct platform_device *pdev)
+{
+	struct resource	 *r;
+	struct clk	 *clk;
+	struct eqep_chip *eqep;
+	struct pinctrl	 *pinctrl;
+
+	u64	period;
+	u16	status;
+	u32	value;
+
+	dev_info(&pdev->dev, "ver. 1.0\n");
+
+	/* Select pins provided through the device tree */
+	pinctrl = devm_pinctrl_get_select_default(&pdev->dev);
+	if (IS_ERR(pinctrl))
+	{
+		dev_warn(&pdev->dev, "unable to select pin group\n");
+	}
+
+	/* Allocate a eqep_driver object */
+	eqep = devm_kzalloc(&pdev->dev, sizeof(struct eqep_chip), GFP_KERNEL);
+	if (!eqep) {
+		dev_err(&pdev->dev, "failed to allocate memory\n");
+		return -ENOMEM;
+	}
+
+	/* Get a handle to the system clock object */
+	clk = devm_clk_get(pdev->dev.parent, "fck");
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "failed to get clock\n");
+		return PTR_ERR(clk);
+	}
+
+	/* Get the frequency of the system clock */
+	eqep->clk_rate = clk_get_rate(clk);
+	if (!eqep->clk_rate) {
+		dev_err(&pdev->dev, "failed to get clock rate\n");
+		return -EINVAL;
+	}
+
+	/* Get a resource containing the IRQ for this eQEP controller */
+	r = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	if (unlikely(!r)) {
+		dev_err(&pdev->dev, "Invalid IRQ resource\n");
+		return -ENODEV;
+	}
+
+	/* Store the irq */
+	eqep->irq = r->start;
+
+	/* Get a resource containing the requested (from DT) memory address and range of eQEP controller */
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!r) {
+		dev_err(&pdev->dev, "no memory resource defined\n");
+		return -ENODEV;
+	}
+
+	/* Remap the eQEP controller memory into our own memory space */
+	eqep->mmio_base = devm_ioremap_resource(&pdev->dev, r);
+	if (IS_ERR(eqep->mmio_base))
+		return PTR_ERR(eqep->mmio_base);
+
+	/* Store the platform device in our eQEP data structure for later usage */
+	eqep->pdev = pdev;
+
+	/* Subscribe to the eQEP interrupt */
+	if (request_irq(eqep->irq, eqep_irq_handler, IRQF_IRQPOLL, "eqep_interrupt", pdev))
+	{
+		dev_err(&pdev->dev, "unable to request irq for eQEP\n");
+		return -ENODEV;
+	}
+
+	/* Register controls to sysfs */
+	if (sysfs_create_group(&pdev->dev.kobj, &eqep_device_attr_group))
+	{
+		dev_err(&pdev->dev, "sysfs creation failed\n");
+		return -EINVAL;
+	}
+
+	/* set QDECCTL */
+	status = 0;	/* default to Quadrature count mode, QSRC1 & QSRC0 = 0 */
+
+	/* set QSRC1 & QSRC0 bits, one of 4 count_modes. */
+	if (!of_property_read_u32(pdev->dev.of_node, "count_mode", &value) && value <= 3) {
+		status |= value << 14;
+
+		/*
+		 * in count up or count down mode, count on rising edge only
+		 * not on both edges.
+		 */
+		if (value >= 2)
+			status |= XCR;
+	}
+	dev_info(&pdev->dev, "count_mode:%d\n", value);
+
+	/* Should we invert the qa input */
+	if (!of_property_read_u32(pdev->dev.of_node, "invert_qa", &value))
+		status = value ? status | QAP : status & ~QAP;
+	dev_info(&pdev->dev, "invert_qa:%d\n", value);
+
+	/* Should we invert the qb input */
+	if (!of_property_read_u32(pdev->dev.of_node, "invert_qb", &value))
+		status = value ? status | QBP : status & ~QBP;
+	dev_info(&pdev->dev, "invert_qb:%d\n", value);
+
+	/* Should we invert the index input */
+	if (!of_property_read_u32(pdev->dev.of_node, "invert_qi", &value))
+		status = value ? status | QIP : status & ~QIP;
+	dev_info(&pdev->dev, "invert_qi:%d\n", value);
+
+	/* Should we invert the strobe input */
+	if (!of_property_read_u32(pdev->dev.of_node, "invert_qs", &value))
+		status = value ? status | QSP : status & ~QSP;
+	dev_info(&pdev->dev, "invert_qs:%d\n", value);
+
+	/* Should we swap the cha and chb inputs */
+	if (!of_property_read_u32(pdev->dev.of_node, "swap_inputs", &value))
+		status = value ? status | SWAP : status & ~SWAP;
+	dev_info(&pdev->dev, "swap_inputs:%d\n", value);
+
+	dev_info(&pdev->dev, "QDECCTL:0x%04x\n", status);
+
+	/* Write the decoder control settings back to the control register */
+	writew(status, eqep->mmio_base + QDECCTL);
+
+	writel( 0, eqep->mmio_base + QPOSINIT);
+	writel(~0, eqep->mmio_base + QPOSMAX);
+	writel( 0, eqep->mmio_base + QPOSCNT);
+
+	dev_info(&pdev->dev, "QPOSINIT:0x%08x\n", readl(eqep->mmio_base + QPOSINIT));
+	dev_info(&pdev->dev, "QPOSMAX:0x%08x\n", readl(eqep->mmio_base + QPOSMAX));
+	dev_info(&pdev->dev, "QPOSCNT:0x%08x\n", readl(eqep->mmio_base + QPOSCNT));
+
+	status = UTOF;		/* Enable Unit Time Period interrupt. */
+	if (!of_property_read_u32(pdev->dev.of_node, "omit_interrupt", &value) && value) {
+		status = 0;	/* no interrupt */
+	}
+	writew(status, eqep->mmio_base + QEINT);
+	dev_info(&pdev->dev, "omit_interrupt:%d\n", value);
+	dev_info(&pdev->dev, "QEINT:0x%04x\n", status);
+
+	/* Calculate the timer ticks per second */
+	period = 1000000000;
+	period = period * eqep->clk_rate;
+	do_div(period, NSEC_PER_SEC);
+
+	/* Set this period into the unit timer period register */
+	writel(period, eqep->mmio_base + QUPRD);
+	dev_info(&pdev->dev, "QUPRD:0x%08x\n", (u32) period);
+
+	/*
+	 * Enable the eQEP with basic position counting turned on
+	 * PHEN - Quadrature position counter enable bit
+	 * UTE	- unit timer enable
+	 * QCLM - latch QPOSLAT to QPOSCNT upon unit timer overflow
+	 * IEL0 - Latch QPOSILAT on index signal.  Rising or falling, IEL[1:0] = 0 is reserved
+	 * SWI	- Software initialization of position count register, i.e. set QPOSCNT <= QPOSINIT,
+	 *  but this bit was not being reset by hardware as advertised in TRM,
+	 *  (so omit & clear QPOSCNT manually elsewhere?)
+	 */
+	status = PHEN | UTE | QCLM | IEL0 | SWI;
+	writew(status, eqep->mmio_base + QEPCTL);
+	dev_info(&pdev->dev, "QEPCTL:0x%04x write\n", status);
+	dev_info(&pdev->dev, "QEPCTL:0x%04x read\n", readw(eqep->mmio_base + QEPCTL));
+
+	/* We default to absolute mode */
+	eqep->op_mode = TIEQEP_MODE_ABSOLUTE;
+
+	/* Enable the power management runtime */
+	pm_runtime_enable(&pdev->dev);
+
+	/* Increment the device usage count and run pm_runtime_resume() */
+	pm_runtime_get_sync(&pdev->dev);
+
+	/* Initialize the notify work struture */
+	INIT_WORK(&eqep->notify_work, notify_handler);
+
+	/* Decrement the device usage count (twice) and run pm_runtime_idle() if zero */
+	pm_runtime_put_sync(&pdev->dev);
+
+	/* Set the platform driver data to the data object we've been creating for the eQEP unit */
+	platform_set_drvdata(pdev, eqep);
+
+	/* Success! */
+	dev_info(&pdev->dev, "irq:%d, clk_rate:%u\n", eqep->irq, eqep->clk_rate);
+	return 0;
+}
+
+/* Remove an instance of the eQEP driver */
+static int eqep_remove(struct platform_device *pdev)
+{
+	/* Get the eQEP driver data from the platform device structure */
+	struct eqep_chip *eqep = platform_get_drvdata(pdev);
+
+	/* Cancel work */
+	cancel_work_sync(&eqep->notify_work);
+
+	/* Unmap from sysfs */
+	sysfs_remove_group(&pdev->dev.kobj, &eqep_device_attr_group);
+
+	/* Release important assets */
+	free_irq(eqep->irq, pdev);
+
+	/* Increment the device usage count and run pm_runtime_resume() */
+	pm_runtime_get_sync(&pdev->dev);
+
+	/* Decrement the device usage count (twice) and run pm_runtime_idle() if zero */
+	pm_runtime_put_sync(&pdev->dev);
+	pm_runtime_put_sync(&pdev->dev);
+
+	/* Disable the runtime power management of this device */
+	pm_runtime_disable(&pdev->dev);
+
+	/* Return success */
+	return 0;
+}
+
+/* Power management suspend device */
+static int eqep_suspend(struct device *dev)
+{
+	/* Get the eqep driver information */
+	struct eqep_chip   *eqep = dev_get_drvdata(dev);
+	u16					tmp;
+
+	/* Shut down interrupts */
+	eqep->prior_qeint = readw(eqep->mmio_base + QEINT);
+	tmp = eqep->prior_qeint & ~UTOF;
+	writew(tmp, eqep->mmio_base + QEINT);
+
+	/* Get the existing state of QEPCTL */
+	eqep->prior_qepctl = readw(eqep->mmio_base + QEPCTL);
+
+	/* Disable eQEP controller */
+	writew(eqep->prior_qepctl & ~PHEN, eqep->mmio_base + QEPCTL);
+
+	/* Decrement the device usage count and run pm_runtime_idle() if zero */
+	pm_runtime_put_sync(dev);
+
+	/* Return success */
+	return 0;
+}
+
+/* Power management wake device back up */
+static int eqep_resume(struct device *dev)
+{
+	/* Get the eqep driver information */
+	struct eqep_chip *eqep = dev_get_drvdata(dev);
+
+	/* Restore interrupt enabled register */
+	writew(eqep->prior_qeint, eqep->mmio_base + QEINT);
+
+	/* Restore prior qep control register */
+	writew(eqep->prior_qepctl, eqep->mmio_base + QEPCTL);
+
+	/* Increment the device usage count and run pm_runtime_resume() */
+	pm_runtime_get_sync(dev);
+
+	/* Success */
+	return 0;
+}
+
+/* create pm functions object */
+static SIMPLE_DEV_PM_OPS(eqep_pm_ops, eqep_suspend, eqep_resume);
+
+/* Platform driver information */
+static struct platform_driver eqep_driver = {
+	.driver = {
+		.name	= "eqep",
+		.owner	= THIS_MODULE,
+		.pm	= &eqep_pm_ops,
+		.of_match_table = eqep_of_match,
+	},
+	.probe = eqep_probe,
+	.remove = eqep_remove,
+};
+
+/* Register this platform driver */
+module_platform_driver(eqep_driver);
+
+/* Module information */
+MODULE_DESCRIPTION("TI eQEP driver");
+MODULE_AUTHOR("Nathaniel R. Lewis");
+MODULE_LICENSE("GPL");
-- 
2.10.1

