Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 799 insertions, 0 deletions

diff --git a/drivers/misc/ad525x_dpot.c b/drivers/misc/ad525x_dpot.c
new file mode 100644
index 000000000..a4e22fd4a
--- /dev/null
+++ b/drivers/misc/ad525x_dpot.c
@@ -0,0 +1,799 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * ad525x_dpot: Driver for the Analog Devices digital potentiometers
+ * Copyright (c) 2009-2010 Analog Devices, Inc.
+ * Author: Michael Hennerich <michael.hennerich@analog.com>
+ *
+ * DEVID		#Wipers		#Positions	Resistor Options (kOhm)
+ * AD5258		1		64		1, 10, 50, 100
+ * AD5259		1		256		5, 10, 50, 100
+ * AD5251		2		64		1, 10, 50, 100
+ * AD5252		2		256		1, 10, 50, 100
+ * AD5255		3		512		25, 250
+ * AD5253		4		64		1, 10, 50, 100
+ * AD5254		4		256		1, 10, 50, 100
+ * AD5160		1		256		5, 10, 50, 100
+ * AD5161		1		256		5, 10, 50, 100
+ * AD5162		2		256		2.5, 10, 50, 100
+ * AD5165		1		256		100
+ * AD5200		1		256		10, 50
+ * AD5201		1		33		10, 50
+ * AD5203		4		64		10, 100
+ * AD5204		4		256		10, 50, 100
+ * AD5206		6		256		10, 50, 100
+ * AD5207		2		256		10, 50, 100
+ * AD5231		1		1024		10, 50, 100
+ * AD5232		2		256		10, 50, 100
+ * AD5233		4		64		10, 50, 100
+ * AD5235		2		1024		25, 250
+ * AD5260		1		256		20, 50, 200
+ * AD5262		2		256		20, 50, 200
+ * AD5263		4		256		20, 50, 200
+ * AD5290		1		256		10, 50, 100
+ * AD5291		1		256		20, 50, 100  (20-TP)
+ * AD5292		1		1024		20, 50, 100  (20-TP)
+ * AD5293		1		1024		20, 50, 100
+ * AD7376		1		128		10, 50, 100, 1M
+ * AD8400		1		256		1, 10, 50, 100
+ * AD8402		2		256		1, 10, 50, 100
+ * AD8403		4		256		1, 10, 50, 100
+ * ADN2850		3		512		25, 250
+ * AD5241		1		256		10, 100, 1M
+ * AD5246		1		128		5, 10, 50, 100
+ * AD5247		1		128		5, 10, 50, 100
+ * AD5245		1		256		5, 10, 50, 100
+ * AD5243		2		256		2.5, 10, 50, 100
+ * AD5248		2		256		2.5, 10, 50, 100
+ * AD5242		2		256		20, 50, 200
+ * AD5280		1		256		20, 50, 200
+ * AD5282		2		256		20, 50, 200
+ * ADN2860		3		512		25, 250
+ * AD5273		1		64		1, 10, 50, 100 (OTP)
+ * AD5171		1		64		5, 10, 50, 100 (OTP)
+ * AD5170		1		256		2.5, 10, 50, 100 (OTP)
+ * AD5172		2		256		2.5, 10, 50, 100 (OTP)
+ * AD5173		2		256		2.5, 10, 50, 100 (OTP)
+ * AD5270		1		1024		20, 50, 100 (50-TP)
+ * AD5271		1		256		20, 50, 100 (50-TP)
+ * AD5272		1		1024		20, 50, 100 (50-TP)
+ * AD5274		1		256		20, 50, 100 (50-TP)
+ *
+ * See Documentation/misc-devices/ad525x_dpot.rst for more info.
+ *
+ * derived from ad5258.c
+ * Copyright (c) 2009 Cyber Switching, Inc.
+ * Author: Chris Verges <chrisv@cyberswitching.com>
+ *
+ * derived from ad5252.c
+ * Copyright (c) 2006-2011 Michael Hennerich <michael.hennerich@analog.com>
+ */
+
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/string_choices.h>
+
+#include "ad525x_dpot.h"
+
+/*
+ * Client data (each client gets its own)
+ */
+
+struct dpot_data {
+	struct ad_dpot_bus_data	bdata;
+	struct mutex update_lock;
+	unsigned int rdac_mask;
+	unsigned int max_pos;
+	unsigned long devid;
+	unsigned int uid;
+	unsigned int feat;
+	unsigned int wipers;
+	u16 rdac_cache[MAX_RDACS];
+	DECLARE_BITMAP(otp_en_mask, MAX_RDACS);
+};
+
+static inline int dpot_read_d8(struct dpot_data *dpot)
+{
+	return dpot->bdata.bops->read_d8(dpot->bdata.client);
+}
+
+static inline int dpot_read_r8d8(struct dpot_data *dpot, u8 reg)
+{
+	return dpot->bdata.bops->read_r8d8(dpot->bdata.client, reg);
+}
+
+static inline int dpot_read_r8d16(struct dpot_data *dpot, u8 reg)
+{
+	return dpot->bdata.bops->read_r8d16(dpot->bdata.client, reg);
+}
+
+static inline int dpot_write_d8(struct dpot_data *dpot, u8 val)
+{
+	return dpot->bdata.bops->write_d8(dpot->bdata.client, val);
+}
+
+static inline int dpot_write_r8d8(struct dpot_data *dpot, u8 reg, u16 val)
+{
+	return dpot->bdata.bops->write_r8d8(dpot->bdata.client, reg, val);
+}
+
+static inline int dpot_write_r8d16(struct dpot_data *dpot, u8 reg, u16 val)
+{
+	return dpot->bdata.bops->write_r8d16(dpot->bdata.client, reg, val);
+}
+
+static s32 dpot_read_spi(struct dpot_data *dpot, u8 reg)
+{
+	unsigned int ctrl = 0;
+	int value;
+
+	if (!(reg & (DPOT_ADDR_EEPROM | DPOT_ADDR_CMD))) {
+
+		if (dpot->feat & F_RDACS_WONLY)
+			return dpot->rdac_cache[reg & DPOT_RDAC_MASK];
+		if (dpot->uid == DPOT_UID(AD5291_ID) ||
+			dpot->uid == DPOT_UID(AD5292_ID) ||
+			dpot->uid == DPOT_UID(AD5293_ID)) {
+
+			value = dpot_read_r8d8(dpot,
+				DPOT_AD5291_READ_RDAC << 2);
+
+			if (value < 0)
+				return value;
+
+			if (dpot->uid == DPOT_UID(AD5291_ID))
+				value = value >> 2;
+
+			return value;
+		} else if (dpot->uid == DPOT_UID(AD5270_ID) ||
+			dpot->uid == DPOT_UID(AD5271_ID)) {
+
+			value = dpot_read_r8d8(dpot,
+				DPOT_AD5270_1_2_4_READ_RDAC << 2);
+
+			if (value < 0)
+				return value;
+
+			if (dpot->uid == DPOT_UID(AD5271_ID))
+				value = value >> 2;
+
+			return value;
+		}
+
+		ctrl = DPOT_SPI_READ_RDAC;
+	} else if (reg & DPOT_ADDR_EEPROM) {
+		ctrl = DPOT_SPI_READ_EEPROM;
+	}
+
+	if (dpot->feat & F_SPI_16BIT)
+		return dpot_read_r8d8(dpot, ctrl);
+	else if (dpot->feat & F_SPI_24BIT)
+		return dpot_read_r8d16(dpot, ctrl);
+
+	return -EFAULT;
+}
+
+static s32 dpot_read_i2c(struct dpot_data *dpot, u8 reg)
+{
+	int value;
+	unsigned int ctrl = 0;
+
+	switch (dpot->uid) {
+	case DPOT_UID(AD5246_ID):
+	case DPOT_UID(AD5247_ID):
+		return dpot_read_d8(dpot);
+	case DPOT_UID(AD5245_ID):
+	case DPOT_UID(AD5241_ID):
+	case DPOT_UID(AD5242_ID):
+	case DPOT_UID(AD5243_ID):
+	case DPOT_UID(AD5248_ID):
+	case DPOT_UID(AD5280_ID):
+	case DPOT_UID(AD5282_ID):
+		ctrl = ((reg & DPOT_RDAC_MASK) == DPOT_RDAC0) ?
+			0 : DPOT_AD5282_RDAC_AB;
+		return dpot_read_r8d8(dpot, ctrl);
+	case DPOT_UID(AD5170_ID):
+	case DPOT_UID(AD5171_ID):
+	case DPOT_UID(AD5273_ID):
+			return dpot_read_d8(dpot);
+	case DPOT_UID(AD5172_ID):
+	case DPOT_UID(AD5173_ID):
+		ctrl = ((reg & DPOT_RDAC_MASK) == DPOT_RDAC0) ?
+			0 : DPOT_AD5172_3_A0;
+		return dpot_read_r8d8(dpot, ctrl);
+	case DPOT_UID(AD5272_ID):
+	case DPOT_UID(AD5274_ID):
+		dpot_write_r8d8(dpot,
+				(DPOT_AD5270_1_2_4_READ_RDAC << 2), 0);
+
+		value = dpot_read_r8d16(dpot, DPOT_AD5270_1_2_4_RDAC << 2);
+		if (value < 0)
+			return value;
+		/*
+		 * AD5272/AD5274 returns high byte first, however
+		 * underling smbus expects low byte first.
+		 */
+		value = swab16(value);
+
+		if (dpot->uid == DPOT_UID(AD5274_ID))
+			value = value >> 2;
+		return value;
+	default:
+		if ((reg & DPOT_REG_TOL) || (dpot->max_pos > 256))
+			return dpot_read_r8d16(dpot, (reg & 0xF8) |
+					((reg & 0x7) << 1));
+		else
+			return dpot_read_r8d8(dpot, reg);
+	}
+}
+
+static s32 dpot_read(struct dpot_data *dpot, u8 reg)
+{
+	if (dpot->feat & F_SPI)
+		return dpot_read_spi(dpot, reg);
+	else
+		return dpot_read_i2c(dpot, reg);
+}
+
+static s32 dpot_write_spi(struct dpot_data *dpot, u8 reg, u16 value)
+{
+	unsigned int val = 0;
+
+	if (!(reg & (DPOT_ADDR_EEPROM | DPOT_ADDR_CMD | DPOT_ADDR_OTP))) {
+		if (dpot->feat & F_RDACS_WONLY)
+			dpot->rdac_cache[reg & DPOT_RDAC_MASK] = value;
+
+		if (dpot->feat & F_AD_APPDATA) {
+			if (dpot->feat & F_SPI_8BIT) {
+				val = ((reg & DPOT_RDAC_MASK) <<
+					DPOT_MAX_POS(dpot->devid)) |
+					value;
+				return dpot_write_d8(dpot, val);
+			} else if (dpot->feat & F_SPI_16BIT) {
+				val = ((reg & DPOT_RDAC_MASK) <<
+					DPOT_MAX_POS(dpot->devid)) |
+					value;
+				return dpot_write_r8d8(dpot, val >> 8,
+					val & 0xFF);
+			} else
+				BUG();
+		} else {
+			if (dpot->uid == DPOT_UID(AD5291_ID) ||
+				dpot->uid == DPOT_UID(AD5292_ID) ||
+				dpot->uid == DPOT_UID(AD5293_ID)) {
+
+				dpot_write_r8d8(dpot, DPOT_AD5291_CTRLREG << 2,
+						DPOT_AD5291_UNLOCK_CMD);
+
+				if (dpot->uid == DPOT_UID(AD5291_ID))
+					value = value << 2;
+
+				return dpot_write_r8d8(dpot,
+					(DPOT_AD5291_RDAC << 2) |
+					(value >> 8), value & 0xFF);
+			} else if (dpot->uid == DPOT_UID(AD5270_ID) ||
+				dpot->uid == DPOT_UID(AD5271_ID)) {
+				dpot_write_r8d8(dpot,
+						DPOT_AD5270_1_2_4_CTRLREG << 2,
+						DPOT_AD5270_1_2_4_UNLOCK_CMD);
+
+				if (dpot->uid == DPOT_UID(AD5271_ID))
+					value = value << 2;
+
+				return dpot_write_r8d8(dpot,
+					(DPOT_AD5270_1_2_4_RDAC << 2) |
+					(value >> 8), value & 0xFF);
+			}
+			val = DPOT_SPI_RDAC | (reg & DPOT_RDAC_MASK);
+		}
+	} else if (reg & DPOT_ADDR_EEPROM) {
+		val = DPOT_SPI_EEPROM | (reg & DPOT_RDAC_MASK);
+	} else if (reg & DPOT_ADDR_CMD) {
+		switch (reg) {
+		case DPOT_DEC_ALL_6DB:
+			val = DPOT_SPI_DEC_ALL_6DB;
+			break;
+		case DPOT_INC_ALL_6DB:
+			val = DPOT_SPI_INC_ALL_6DB;
+			break;
+		case DPOT_DEC_ALL:
+			val = DPOT_SPI_DEC_ALL;
+			break;
+		case DPOT_INC_ALL:
+			val = DPOT_SPI_INC_ALL;
+			break;
+		}
+	} else if (reg & DPOT_ADDR_OTP) {
+		if (dpot->uid == DPOT_UID(AD5291_ID) ||
+			dpot->uid == DPOT_UID(AD5292_ID)) {
+			return dpot_write_r8d8(dpot,
+				DPOT_AD5291_STORE_XTPM << 2, 0);
+		} else if (dpot->uid == DPOT_UID(AD5270_ID) ||
+			dpot->uid == DPOT_UID(AD5271_ID)) {
+			return dpot_write_r8d8(dpot,
+				DPOT_AD5270_1_2_4_STORE_XTPM << 2, 0);
+		}
+	} else
+		BUG();
+
+	if (dpot->feat & F_SPI_16BIT)
+		return dpot_write_r8d8(dpot, val, value);
+	else if (dpot->feat & F_SPI_24BIT)
+		return dpot_write_r8d16(dpot, val, value);
+
+	return -EFAULT;
+}
+
+static s32 dpot_write_i2c(struct dpot_data *dpot, u8 reg, u16 value)
+{
+	/* Only write the instruction byte for certain commands */
+	unsigned int tmp = 0, ctrl = 0;
+
+	switch (dpot->uid) {
+	case DPOT_UID(AD5246_ID):
+	case DPOT_UID(AD5247_ID):
+		return dpot_write_d8(dpot, value);
+
+	case DPOT_UID(AD5245_ID):
+	case DPOT_UID(AD5241_ID):
+	case DPOT_UID(AD5242_ID):
+	case DPOT_UID(AD5243_ID):
+	case DPOT_UID(AD5248_ID):
+	case DPOT_UID(AD5280_ID):
+	case DPOT_UID(AD5282_ID):
+		ctrl = ((reg & DPOT_RDAC_MASK) == DPOT_RDAC0) ?
+			0 : DPOT_AD5282_RDAC_AB;
+		return dpot_write_r8d8(dpot, ctrl, value);
+	case DPOT_UID(AD5171_ID):
+	case DPOT_UID(AD5273_ID):
+		if (reg & DPOT_ADDR_OTP) {
+			tmp = dpot_read_d8(dpot);
+			if (tmp >> 6) /* Ready to Program? */
+				return -EFAULT;
+			ctrl = DPOT_AD5273_FUSE;
+		}
+		return dpot_write_r8d8(dpot, ctrl, value);
+	case DPOT_UID(AD5172_ID):
+	case DPOT_UID(AD5173_ID):
+		ctrl = ((reg & DPOT_RDAC_MASK) == DPOT_RDAC0) ?
+			0 : DPOT_AD5172_3_A0;
+		if (reg & DPOT_ADDR_OTP) {
+			tmp = dpot_read_r8d16(dpot, ctrl);
+			if (tmp >> 14) /* Ready to Program? */
+				return -EFAULT;
+			ctrl |= DPOT_AD5170_2_3_FUSE;
+		}
+		return dpot_write_r8d8(dpot, ctrl, value);
+	case DPOT_UID(AD5170_ID):
+		if (reg & DPOT_ADDR_OTP) {
+			tmp = dpot_read_r8d16(dpot, tmp);
+			if (tmp >> 14) /* Ready to Program? */
+				return -EFAULT;
+			ctrl = DPOT_AD5170_2_3_FUSE;
+		}
+		return dpot_write_r8d8(dpot, ctrl, value);
+	case DPOT_UID(AD5272_ID):
+	case DPOT_UID(AD5274_ID):
+		dpot_write_r8d8(dpot, DPOT_AD5270_1_2_4_CTRLREG << 2,
+				DPOT_AD5270_1_2_4_UNLOCK_CMD);
+
+		if (reg & DPOT_ADDR_OTP)
+			return dpot_write_r8d8(dpot,
+					DPOT_AD5270_1_2_4_STORE_XTPM << 2, 0);
+
+		if (dpot->uid == DPOT_UID(AD5274_ID))
+			value = value << 2;
+
+		return dpot_write_r8d8(dpot, (DPOT_AD5270_1_2_4_RDAC << 2) |
+				       (value >> 8), value & 0xFF);
+	default:
+		if (reg & DPOT_ADDR_CMD)
+			return dpot_write_d8(dpot, reg);
+
+		if (dpot->max_pos > 256)
+			return dpot_write_r8d16(dpot, (reg & 0xF8) |
+						((reg & 0x7) << 1), value);
+		else
+			/* All other registers require instruction + data bytes */
+			return dpot_write_r8d8(dpot, reg, value);
+	}
+}
+
+static s32 dpot_write(struct dpot_data *dpot, u8 reg, u16 value)
+{
+	if (dpot->feat & F_SPI)
+		return dpot_write_spi(dpot, reg, value);
+	else
+		return dpot_write_i2c(dpot, reg, value);
+}
+
+/* sysfs functions */
+
+static ssize_t sysfs_show_reg(struct device *dev,
+			      struct device_attribute *attr,
+			      char *buf, u32 reg)
+{
+	struct dpot_data *data = dev_get_drvdata(dev);
+	s32 value;
+
+	if (reg & DPOT_ADDR_OTP_EN)
+		return sprintf(buf, "%s\n", str_enabled_disabled(
+			test_bit(DPOT_RDAC_MASK & reg, data->otp_en_mask)));
+
+	mutex_lock(&data->update_lock);
+	value = dpot_read(data, reg);
+	mutex_unlock(&data->update_lock);
+
+	if (value < 0)
+		return -EINVAL;
+	/*
+	 * Let someone else deal with converting this ...
+	 * the tolerance is a two-byte value where the MSB
+	 * is a sign + integer value, and the LSB is a
+	 * decimal value.  See page 18 of the AD5258
+	 * datasheet (Rev. A) for more details.
+	 */
+
+	if (reg & DPOT_REG_TOL)
+		return sprintf(buf, "0x%04x\n", value & 0xFFFF);
+	else
+		return sprintf(buf, "%u\n", value & data->rdac_mask);
+}
+
+static ssize_t sysfs_set_reg(struct device *dev,
+			     struct device_attribute *attr,
+			     const char *buf, size_t count, u32 reg)
+{
+	struct dpot_data *data = dev_get_drvdata(dev);
+	unsigned long value;
+	int err;
+
+	if (reg & DPOT_ADDR_OTP_EN) {
+		if (sysfs_streq(buf, "enabled"))
+			set_bit(DPOT_RDAC_MASK & reg, data->otp_en_mask);
+		else
+			clear_bit(DPOT_RDAC_MASK & reg, data->otp_en_mask);
+
+		return count;
+	}
+
+	if ((reg & DPOT_ADDR_OTP) &&
+		!test_bit(DPOT_RDAC_MASK & reg, data->otp_en_mask))
+		return -EPERM;
+
+	err = kstrtoul(buf, 10, &value);
+	if (err)
+		return err;
+
+	if (value > data->rdac_mask)
+		value = data->rdac_mask;
+
+	mutex_lock(&data->update_lock);
+	dpot_write(data, reg, value);
+	if (reg & DPOT_ADDR_EEPROM)
+		msleep(26);	/* Sleep while the EEPROM updates */
+	else if (reg & DPOT_ADDR_OTP)
+		msleep(400);	/* Sleep while the OTP updates */
+	mutex_unlock(&data->update_lock);
+
+	return count;
+}
+
+static ssize_t sysfs_do_cmd(struct device *dev,
+			    struct device_attribute *attr,
+			    const char *buf, size_t count, u32 reg)
+{
+	struct dpot_data *data = dev_get_drvdata(dev);
+
+	mutex_lock(&data->update_lock);
+	dpot_write(data, reg, 0);
+	mutex_unlock(&data->update_lock);
+
+	return count;
+}
+
+/* ------------------------------------------------------------------------- */
+
+#define DPOT_DEVICE_SHOW(_name, _reg) static ssize_t \
+show_##_name(struct device *dev, \
+			  struct device_attribute *attr, char *buf) \
+{ \
+	return sysfs_show_reg(dev, attr, buf, _reg); \
+}
+
+#define DPOT_DEVICE_SET(_name, _reg) static ssize_t \
+set_##_name(struct device *dev, \
+			 struct device_attribute *attr, \
+			 const char *buf, size_t count) \
+{ \
+	return sysfs_set_reg(dev, attr, buf, count, _reg); \
+}
+
+#define DPOT_DEVICE_SHOW_SET(name, reg) \
+DPOT_DEVICE_SHOW(name, reg) \
+DPOT_DEVICE_SET(name, reg) \
+static DEVICE_ATTR(name, S_IWUSR | S_IRUGO, show_##name, set_##name)
+
+#define DPOT_DEVICE_SHOW_ONLY(name, reg) \
+DPOT_DEVICE_SHOW(name, reg) \
+static DEVICE_ATTR(name, S_IWUSR | S_IRUGO, show_##name, NULL)
+
+DPOT_DEVICE_SHOW_SET(rdac0, DPOT_ADDR_RDAC | DPOT_RDAC0);
+DPOT_DEVICE_SHOW_SET(eeprom0, DPOT_ADDR_EEPROM | DPOT_RDAC0);
+DPOT_DEVICE_SHOW_ONLY(tolerance0, DPOT_ADDR_EEPROM | DPOT_TOL_RDAC0);
+DPOT_DEVICE_SHOW_SET(otp0, DPOT_ADDR_OTP | DPOT_RDAC0);
+DPOT_DEVICE_SHOW_SET(otp0en, DPOT_ADDR_OTP_EN | DPOT_RDAC0);
+
+DPOT_DEVICE_SHOW_SET(rdac1, DPOT_ADDR_RDAC | DPOT_RDAC1);
+DPOT_DEVICE_SHOW_SET(eeprom1, DPOT_ADDR_EEPROM | DPOT_RDAC1);
+DPOT_DEVICE_SHOW_ONLY(tolerance1, DPOT_ADDR_EEPROM | DPOT_TOL_RDAC1);
+DPOT_DEVICE_SHOW_SET(otp1, DPOT_ADDR_OTP | DPOT_RDAC1);
+DPOT_DEVICE_SHOW_SET(otp1en, DPOT_ADDR_OTP_EN | DPOT_RDAC1);
+
+DPOT_DEVICE_SHOW_SET(rdac2, DPOT_ADDR_RDAC | DPOT_RDAC2);
+DPOT_DEVICE_SHOW_SET(eeprom2, DPOT_ADDR_EEPROM | DPOT_RDAC2);
+DPOT_DEVICE_SHOW_ONLY(tolerance2, DPOT_ADDR_EEPROM | DPOT_TOL_RDAC2);
+DPOT_DEVICE_SHOW_SET(otp2, DPOT_ADDR_OTP | DPOT_RDAC2);
+DPOT_DEVICE_SHOW_SET(otp2en, DPOT_ADDR_OTP_EN | DPOT_RDAC2);
+
+DPOT_DEVICE_SHOW_SET(rdac3, DPOT_ADDR_RDAC | DPOT_RDAC3);
+DPOT_DEVICE_SHOW_SET(eeprom3, DPOT_ADDR_EEPROM | DPOT_RDAC3);
+DPOT_DEVICE_SHOW_ONLY(tolerance3, DPOT_ADDR_EEPROM | DPOT_TOL_RDAC3);
+DPOT_DEVICE_SHOW_SET(otp3, DPOT_ADDR_OTP | DPOT_RDAC3);
+DPOT_DEVICE_SHOW_SET(otp3en, DPOT_ADDR_OTP_EN | DPOT_RDAC3);
+
+DPOT_DEVICE_SHOW_SET(rdac4, DPOT_ADDR_RDAC | DPOT_RDAC4);
+DPOT_DEVICE_SHOW_SET(eeprom4, DPOT_ADDR_EEPROM | DPOT_RDAC4);
+DPOT_DEVICE_SHOW_ONLY(tolerance4, DPOT_ADDR_EEPROM | DPOT_TOL_RDAC4);
+DPOT_DEVICE_SHOW_SET(otp4, DPOT_ADDR_OTP | DPOT_RDAC4);
+DPOT_DEVICE_SHOW_SET(otp4en, DPOT_ADDR_OTP_EN | DPOT_RDAC4);
+
+DPOT_DEVICE_SHOW_SET(rdac5, DPOT_ADDR_RDAC | DPOT_RDAC5);
+DPOT_DEVICE_SHOW_SET(eeprom5, DPOT_ADDR_EEPROM | DPOT_RDAC5);
+DPOT_DEVICE_SHOW_ONLY(tolerance5, DPOT_ADDR_EEPROM | DPOT_TOL_RDAC5);
+DPOT_DEVICE_SHOW_SET(otp5, DPOT_ADDR_OTP | DPOT_RDAC5);
+DPOT_DEVICE_SHOW_SET(otp5en, DPOT_ADDR_OTP_EN | DPOT_RDAC5);
+
+static const struct attribute *dpot_attrib_wipers[] = {
+	&dev_attr_rdac0.attr,
+	&dev_attr_rdac1.attr,
+	&dev_attr_rdac2.attr,
+	&dev_attr_rdac3.attr,
+	&dev_attr_rdac4.attr,
+	&dev_attr_rdac5.attr,
+	NULL
+};
+
+static const struct attribute *dpot_attrib_eeprom[] = {
+	&dev_attr_eeprom0.attr,
+	&dev_attr_eeprom1.attr,
+	&dev_attr_eeprom2.attr,
+	&dev_attr_eeprom3.attr,
+	&dev_attr_eeprom4.attr,
+	&dev_attr_eeprom5.attr,
+	NULL
+};
+
+static const struct attribute *dpot_attrib_otp[] = {
+	&dev_attr_otp0.attr,
+	&dev_attr_otp1.attr,
+	&dev_attr_otp2.attr,
+	&dev_attr_otp3.attr,
+	&dev_attr_otp4.attr,
+	&dev_attr_otp5.attr,
+	NULL
+};
+
+static const struct attribute *dpot_attrib_otp_en[] = {
+	&dev_attr_otp0en.attr,
+	&dev_attr_otp1en.attr,
+	&dev_attr_otp2en.attr,
+	&dev_attr_otp3en.attr,
+	&dev_attr_otp4en.attr,
+	&dev_attr_otp5en.attr,
+	NULL
+};
+
+static const struct attribute *dpot_attrib_tolerance[] = {
+	&dev_attr_tolerance0.attr,
+	&dev_attr_tolerance1.attr,
+	&dev_attr_tolerance2.attr,
+	&dev_attr_tolerance3.attr,
+	&dev_attr_tolerance4.attr,
+	&dev_attr_tolerance5.attr,
+	NULL
+};
+
+/* ------------------------------------------------------------------------- */
+
+#define DPOT_DEVICE_DO_CMD(_name, _cmd) static ssize_t \
+set_##_name(struct device *dev, \
+			 struct device_attribute *attr, \
+			 const char *buf, size_t count) \
+{ \
+	return sysfs_do_cmd(dev, attr, buf, count, _cmd); \
+} \
+static DEVICE_ATTR(_name, S_IWUSR | S_IRUGO, NULL, set_##_name)
+
+DPOT_DEVICE_DO_CMD(inc_all, DPOT_INC_ALL);
+DPOT_DEVICE_DO_CMD(dec_all, DPOT_DEC_ALL);
+DPOT_DEVICE_DO_CMD(inc_all_6db, DPOT_INC_ALL_6DB);
+DPOT_DEVICE_DO_CMD(dec_all_6db, DPOT_DEC_ALL_6DB);
+
+static struct attribute *ad525x_attributes_commands[] = {
+	&dev_attr_inc_all.attr,
+	&dev_attr_dec_all.attr,
+	&dev_attr_inc_all_6db.attr,
+	&dev_attr_dec_all_6db.attr,
+	NULL
+};
+
+static struct attribute *ad525x_attributes[] = {
+	&dev_attr_rdac0.attr,
+	&dev_attr_rdac1.attr,
+	&dev_attr_rdac2.attr,
+	&dev_attr_rdac3.attr,
+	&dev_attr_rdac4.attr,
+	&dev_attr_rdac5.attr,
+	&dev_attr_eeprom0.attr,
+	&dev_attr_eeprom1.attr,
+	&dev_attr_eeprom2.attr,
+	&dev_attr_eeprom3.attr,
+	&dev_attr_eeprom4.attr,
+	&dev_attr_eeprom5.attr,
+	&dev_attr_tolerance0.attr,
+	&dev_attr_tolerance1.attr,
+	&dev_attr_tolerance2.attr,
+	&dev_attr_tolerance3.attr,
+	&dev_attr_tolerance4.attr,
+	&dev_attr_tolerance5.attr,
+	&dev_attr_otp0.attr,
+	&dev_attr_otp1.attr,
+	&dev_attr_otp2.attr,
+	&dev_attr_otp3.attr,
+	&dev_attr_otp4.attr,
+	&dev_attr_otp5.attr,
+	&dev_attr_otp0en.attr,
+	&dev_attr_otp1en.attr,
+	&dev_attr_otp2en.attr,
+	&dev_attr_otp3en.attr,
+	&dev_attr_otp4en.attr,
+	&dev_attr_otp5en.attr,
+	&dev_attr_inc_all.attr,
+	&dev_attr_dec_all.attr,
+	&dev_attr_inc_all_6db.attr,
+	&dev_attr_dec_all_6db.attr,
+	NULL
+};
+
+static int ad525x_attr_index(struct attribute *attr,
+			     const struct attribute * const *attrs)
+{
+	int i;
+
+	for (i = 0; attrs[i]; i++)
+		if (attr == attrs[i])
+			return i;
+
+	return -ENOENT;
+}
+
+static bool ad525x_is_command_attr(struct attribute *attr)
+{
+	int i;
+
+	for (i = 0; ad525x_attributes_commands[i]; i++) {
+		if (attr == ad525x_attributes_commands[i])
+			return true;
+	}
+
+	return false;
+}
+
+static umode_t ad525x_is_visible(struct kobject *kobj, struct attribute *attr,
+				 int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct dpot_data *data = dev_get_drvdata(dev);
+	int rdac;
+
+	if (!data)
+		return 0;
+
+	rdac = ad525x_attr_index(attr, dpot_attrib_wipers);
+	if (rdac >= 0)
+		return data->wipers & BIT(rdac) ? attr->mode : 0;
+
+	rdac = ad525x_attr_index(attr, dpot_attrib_eeprom);
+	if (rdac >= 0)
+		return (data->wipers & BIT(rdac)) && (data->feat & F_CMD_EEP) ?
+			attr->mode : 0;
+
+	rdac = ad525x_attr_index(attr, dpot_attrib_tolerance);
+	if (rdac >= 0)
+		return (data->wipers & BIT(rdac)) && (data->feat & F_CMD_TOL) ?
+			attr->mode : 0;
+
+	rdac = ad525x_attr_index(attr, dpot_attrib_otp);
+	if (rdac >= 0)
+		return (data->wipers & BIT(rdac)) && (data->feat & F_CMD_OTP) ?
+			attr->mode : 0;
+
+	rdac = ad525x_attr_index(attr, dpot_attrib_otp_en);
+	if (rdac >= 0)
+		return (data->wipers & BIT(rdac)) && (data->feat & F_CMD_OTP) ?
+			attr->mode : 0;
+
+	if (ad525x_is_command_attr(attr))
+		return data->feat & F_CMD_INC ? attr->mode : 0;
+
+	return attr->mode;
+}
+
+static const struct attribute_group ad525x_group = {
+	.attrs = ad525x_attributes,
+	.is_visible = ad525x_is_visible,
+};
+
+const struct attribute_group *ad_dpot_groups[] = {
+	&ad525x_group,
+	NULL
+};
+EXPORT_SYMBOL(ad_dpot_groups);
+
+int ad_dpot_probe(struct device *dev,
+		struct ad_dpot_bus_data *bdata, unsigned long devid,
+			    const char *name)
+{
+
+	struct dpot_data *data;
+	int i;
+
+	data = kzalloc_obj(struct dpot_data);
+	if (!data) {
+		dev_err(dev, "failed to create client for %s ID 0x%lX\n",
+			name, devid);
+		return -ENOMEM;
+	}
+
+	dev_set_drvdata(dev, data);
+	mutex_init(&data->update_lock);
+
+	data->bdata = *bdata;
+	data->devid = devid;
+
+	data->max_pos = 1 << DPOT_MAX_POS(devid);
+	data->rdac_mask = data->max_pos - 1;
+	data->feat = DPOT_FEAT(devid);
+	data->uid = DPOT_UID(devid);
+	data->wipers = DPOT_WIPERS(devid);
+
+	for (i = DPOT_RDAC0; i < MAX_RDACS; i++)
+		if (data->wipers & BIT(i)) {
+			/* power-up midscale */
+			if (data->feat & F_RDACS_WONLY)
+				data->rdac_cache[i] = data->max_pos / 2;
+		}
+
+	dev_info(dev, "%s %d-Position Digital Potentiometer registered\n",
+		 name, data->max_pos);
+
+	return 0;
+}
+EXPORT_SYMBOL(ad_dpot_probe);
+
+void ad_dpot_remove(struct device *dev)
+{
+	struct dpot_data *data = dev_get_drvdata(dev);
+
+	kfree(data);
+}
+EXPORT_SYMBOL(ad_dpot_remove);
+
+
+MODULE_AUTHOR("Chris Verges <chrisv@cyberswitching.com>, "
+	      "Michael Hennerich <michael.hennerich@analog.com>");
+MODULE_DESCRIPTION("Digital potentiometer driver");
+MODULE_LICENSE("GPL");