dmaengine: add Qualcomm Technologies HIDMA management driver

The Qualcomm Technologies HIDMA device has been designed to support
virtualization technology. The driver has been divided into two to follow
the hardware design.

1. HIDMA Management driver
2. HIDMA Channel driver

Each HIDMA HW consists of multiple channels. These channels share some set
of common parameters. These parameters are initialized by the management
driver during power up. Same management driver is used for monitoring the
execution of the channels. Management driver can change the performance
behavior dynamically such as bandwidth allocation and prioritization.

The management driver is executed in host context and is the main
management entity for all channels provided by the device.
Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

Documentation/ABI/testing/sysfs-platform-hidma-mgmt

+What:		/sys/devices/platform/hidma-mgmt*/chanops/chan*/priority
+		/sys/devices/platform/QCOM8060:*/chanops/chan*/priority
+Date:		Nov 2015
+KernelVersion:	4.4
+Contact:	"Sinan Kaya <okaya@cudeaurora.org>"
+Description:
+		Contains either 0 or 1 and indicates if the DMA channel is a
+		low priority (0) or high priority (1) channel.
+
+What:		/sys/devices/platform/hidma-mgmt*/chanops/chan*/weight
+		/sys/devices/platform/QCOM8060:*/chanops/chan*/weight
+Date:		Nov 2015
+KernelVersion:	4.4
+Contact:	"Sinan Kaya <okaya@cudeaurora.org>"
+Description:
+		Contains 0..15 and indicates the weight of the channel among
+		equal priority channels during round robin scheduling.
+
+What:		/sys/devices/platform/hidma-mgmt*/chreset_timeout_cycles
+		/sys/devices/platform/QCOM8060:*/chreset_timeout_cycles
+Date:		Nov 2015
+KernelVersion:	4.4
+Contact:	"Sinan Kaya <okaya@cudeaurora.org>"
+Description:
+		Contains the platform specific cycle value to wait after a
+		reset command is issued. If the value is chosen too short,
+		then the HW will issue a reset failure interrupt. The value
+		is platform specific and should not be changed without
+		consultance.
+
+What:		/sys/devices/platform/hidma-mgmt*/dma_channels
+		/sys/devices/platform/QCOM8060:*/dma_channels
+Date:		Nov 2015
+KernelVersion:	4.4
+Contact:	"Sinan Kaya <okaya@cudeaurora.org>"
+Description:
+		Contains the number of dma channels supported by one instance
+		of HIDMA hardware. The value may change from chip to chip.
+
+What:		/sys/devices/platform/hidma-mgmt*/hw_version_major
+		/sys/devices/platform/QCOM8060:*/hw_version_major
+Date:		Nov 2015
+KernelVersion:	4.4
+Contact:	"Sinan Kaya <okaya@cudeaurora.org>"
+Description:
+		Version number major for the hardware.
+
+What:		/sys/devices/platform/hidma-mgmt*/hw_version_minor
+		/sys/devices/platform/QCOM8060:*/hw_version_minor
+Date:		Nov 2015
+KernelVersion:	4.4
+Contact:	"Sinan Kaya <okaya@cudeaurora.org>"
+Description:
+		Version number minor for the hardware.
+
+What:		/sys/devices/platform/hidma-mgmt*/max_rd_xactions
+		/sys/devices/platform/QCOM8060:*/max_rd_xactions
+Date:		Nov 2015
+KernelVersion:	4.4
+Contact:	"Sinan Kaya <okaya@cudeaurora.org>"
+Description:
+		Contains a value between 0 and 31. Maximum number of
+		read transactions that can be issued back to back.
+		Choosing a higher number gives better performance but
+		can also cause performance reduction to other peripherals
+		sharing the same bus.
+
+What:		/sys/devices/platform/hidma-mgmt*/max_read_request
+		/sys/devices/platform/QCOM8060:*/max_read_request
+Date:		Nov 2015
+KernelVersion:	4.4
+Contact:	"Sinan Kaya <okaya@cudeaurora.org>"
+Description:
+		Size of each read request. The value needs to be a power
+		of two and can be between 128 and 1024.
+
+What:		/sys/devices/platform/hidma-mgmt*/max_wr_xactions
+		/sys/devices/platform/QCOM8060:*/max_wr_xactions
+Date:		Nov 2015
+KernelVersion:	4.4
+Contact:	"Sinan Kaya <okaya@cudeaurora.org>"
+Description:
+		Contains a value between 0 and 31. Maximum number of
+		write transactions that can be issued back to back.
+		Choosing a higher number gives better performance but
+		can also cause performance reduction to other peripherals
+		sharing the same bus.
+
+
+What:		/sys/devices/platform/hidma-mgmt*/max_write_request
+		/sys/devices/platform/QCOM8060:*/max_write_request
+Date:		Nov 2015
+KernelVersion:	4.4
+Contact:	"Sinan Kaya <okaya@cudeaurora.org>"
+Description:
+		Size of each write request. The value needs to be a power
+		of two and can be between 128 and 1024.

drivers/dma/qcom/Kconfig

@@ -6,3 +6,14 @@ config QCOM_BAM_DMA
 	---help---
 	  Enable support for the QCOM BAM DMA controller.  This controller
 	  provides DMA capabilities for a variety of on-chip devices.
+
+config QCOM_HIDMA_MGMT
+	tristate "Qualcomm Technologies HIDMA Management support"
+	select DMA_ENGINE
+	help
+	  Enable support for the Qualcomm Technologies HIDMA Management.
+	  Each DMA device requires one management interface driver
+	  for basic initialization before QCOM_HIDMA channel driver can
+	  start managing the channels. In a virtualized environment,
+	  the guest OS would run QCOM_HIDMA channel driver and the
+	  host would run the QCOM_HIDMA_MGMT management driver.

drivers/dma/qcom/Makefile

 obj-$(CONFIG_QCOM_BAM_DMA) += bam_dma.o
+obj-$(CONFIG_QCOM_HIDMA_MGMT) += hdma_mgmt.o
+hdma_mgmt-objs	 := hidma_mgmt.o hidma_mgmt_sys.o

drivers/dma/qcom/hidma_mgmt.c

+/*
+ * Qualcomm Technologies HIDMA DMA engine Management interface
+ *
+ * Copyright (c) 2015, The Linux Foundation. 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 version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * 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.
+ */
+
+#include <linux/dmaengine.h>
+#include <linux/acpi.h>
+#include <linux/of.h>
+#include <linux/property.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/slab.h>
+#include <linux/pm_runtime.h>
+#include <linux/bitops.h>
+
+#include "hidma_mgmt.h"
+
+#define HIDMA_QOS_N_OFFSET		0x300
+#define HIDMA_CFG_OFFSET		0x400
+#define HIDMA_MAX_BUS_REQ_LEN_OFFSET	0x41C
+#define HIDMA_MAX_XACTIONS_OFFSET	0x420
+#define HIDMA_HW_VERSION_OFFSET	0x424
+#define HIDMA_CHRESET_TIMEOUT_OFFSET	0x418
+
+#define HIDMA_MAX_WR_XACTIONS_MASK	GENMASK(4, 0)
+#define HIDMA_MAX_RD_XACTIONS_MASK	GENMASK(4, 0)
+#define HIDMA_WEIGHT_MASK		GENMASK(6, 0)
+#define HIDMA_MAX_BUS_REQ_LEN_MASK	GENMASK(15, 0)
+#define HIDMA_CHRESET_TIMEOUT_MASK	GENMASK(19, 0)
+
+#define HIDMA_MAX_WR_XACTIONS_BIT_POS	16
+#define HIDMA_MAX_BUS_WR_REQ_BIT_POS	16
+#define HIDMA_WRR_BIT_POS		8
+#define HIDMA_PRIORITY_BIT_POS		15
+
+#define HIDMA_AUTOSUSPEND_TIMEOUT	2000
+#define HIDMA_MAX_CHANNEL_WEIGHT	15
+
+int hidma_mgmt_setup(struct hidma_mgmt_dev *mgmtdev)
+{
+	unsigned int i;
+	u32 val;
+
+	if (!is_power_of_2(mgmtdev->max_write_request) ||
+	    (mgmtdev->max_write_request < 128) ||
+	    (mgmtdev->max_write_request > 1024)) {
+		dev_err(&mgmtdev->pdev->dev, "invalid write request %d\n",
+			mgmtdev->max_write_request);
+		return -EINVAL;
+	}
+
+	if (!is_power_of_2(mgmtdev->max_read_request) ||
+	    (mgmtdev->max_read_request < 128) ||
+	    (mgmtdev->max_read_request > 1024)) {
+		dev_err(&mgmtdev->pdev->dev, "invalid read request %d\n",
+			mgmtdev->max_read_request);
+		return -EINVAL;
+	}
+
+	if (mgmtdev->max_wr_xactions > HIDMA_MAX_WR_XACTIONS_MASK) {
+		dev_err(&mgmtdev->pdev->dev,
+			"max_wr_xactions cannot be bigger than %ld\n",
+			HIDMA_MAX_WR_XACTIONS_MASK);
+		return -EINVAL;
+	}
+
+	if (mgmtdev->max_rd_xactions > HIDMA_MAX_RD_XACTIONS_MASK) {
+		dev_err(&mgmtdev->pdev->dev,
+			"max_rd_xactions cannot be bigger than %ld\n",
+			HIDMA_MAX_RD_XACTIONS_MASK);
+		return -EINVAL;
+	}
+
+	for (i = 0; i < mgmtdev->dma_channels; i++) {
+		if (mgmtdev->priority[i] > 1) {
+			dev_err(&mgmtdev->pdev->dev,
+				"priority can be 0 or 1\n");
+			return -EINVAL;
+		}
+
+		if (mgmtdev->weight[i] > HIDMA_MAX_CHANNEL_WEIGHT) {
+			dev_err(&mgmtdev->pdev->dev,
+				"max value of weight can be %d.\n",
+				HIDMA_MAX_CHANNEL_WEIGHT);
+			return -EINVAL;
+		}
+
+		/* weight needs to be at least one */
+		if (mgmtdev->weight[i] == 0)
+			mgmtdev->weight[i] = 1;
+	}
+
+	pm_runtime_get_sync(&mgmtdev->pdev->dev);
+	val = readl(mgmtdev->virtaddr + HIDMA_MAX_BUS_REQ_LEN_OFFSET);
+	val &= ~(HIDMA_MAX_BUS_REQ_LEN_MASK << HIDMA_MAX_BUS_WR_REQ_BIT_POS);
+	val |= mgmtdev->max_write_request << HIDMA_MAX_BUS_WR_REQ_BIT_POS;
+	val &= ~HIDMA_MAX_BUS_REQ_LEN_MASK;
+	val |= mgmtdev->max_read_request;
+	writel(val, mgmtdev->virtaddr + HIDMA_MAX_BUS_REQ_LEN_OFFSET);
+
+	val = readl(mgmtdev->virtaddr + HIDMA_MAX_XACTIONS_OFFSET);
+	val &= ~(HIDMA_MAX_WR_XACTIONS_MASK << HIDMA_MAX_WR_XACTIONS_BIT_POS);
+	val |= mgmtdev->max_wr_xactions << HIDMA_MAX_WR_XACTIONS_BIT_POS;
+	val &= ~HIDMA_MAX_RD_XACTIONS_MASK;
+	val |= mgmtdev->max_rd_xactions;
+	writel(val, mgmtdev->virtaddr + HIDMA_MAX_XACTIONS_OFFSET);
+
+	mgmtdev->hw_version =
+	    readl(mgmtdev->virtaddr + HIDMA_HW_VERSION_OFFSET);
+	mgmtdev->hw_version_major = (mgmtdev->hw_version >> 28) & 0xF;
+	mgmtdev->hw_version_minor = (mgmtdev->hw_version >> 16) & 0xF;
+
+	for (i = 0; i < mgmtdev->dma_channels; i++) {
+		u32 weight = mgmtdev->weight[i];
+		u32 priority = mgmtdev->priority[i];
+
+		val = readl(mgmtdev->virtaddr + HIDMA_QOS_N_OFFSET + (4 * i));
+		val &= ~(1 << HIDMA_PRIORITY_BIT_POS);
+		val |= (priority & 0x1) << HIDMA_PRIORITY_BIT_POS;
+		val &= ~(HIDMA_WEIGHT_MASK << HIDMA_WRR_BIT_POS);
+		val |= (weight & HIDMA_WEIGHT_MASK) << HIDMA_WRR_BIT_POS;
+		writel(val, mgmtdev->virtaddr + HIDMA_QOS_N_OFFSET + (4 * i));
+	}
+
+	val = readl(mgmtdev->virtaddr + HIDMA_CHRESET_TIMEOUT_OFFSET);
+	val &= ~HIDMA_CHRESET_TIMEOUT_MASK;
+	val |= mgmtdev->chreset_timeout_cycles & HIDMA_CHRESET_TIMEOUT_MASK;
+	writel(val, mgmtdev->virtaddr + HIDMA_CHRESET_TIMEOUT_OFFSET);
+
+	pm_runtime_mark_last_busy(&mgmtdev->pdev->dev);
+	pm_runtime_put_autosuspend(&mgmtdev->pdev->dev);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(hidma_mgmt_setup);
+
+static int hidma_mgmt_probe(struct platform_device *pdev)
+{
+	struct hidma_mgmt_dev *mgmtdev;
+	struct resource *res;
+	void __iomem *virtaddr;
+	int irq;
+	int rc;
+	u32 val;
+
+	pm_runtime_set_autosuspend_delay(&pdev->dev, HIDMA_AUTOSUSPEND_TIMEOUT);
+	pm_runtime_use_autosuspend(&pdev->dev);
+	pm_runtime_set_active(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
+	pm_runtime_get_sync(&pdev->dev);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	virtaddr = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(virtaddr)) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "irq resources not found\n");
+		rc = irq;
+		goto out;
+	}
+
+	mgmtdev = devm_kzalloc(&pdev->dev, sizeof(*mgmtdev), GFP_KERNEL);
+	if (!mgmtdev) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	mgmtdev->pdev = pdev;
+	mgmtdev->addrsize = resource_size(res);
+	mgmtdev->virtaddr = virtaddr;
+
+	rc = device_property_read_u32(&pdev->dev, "dma-channels",
+				      &mgmtdev->dma_channels);
+	if (rc) {
+		dev_err(&pdev->dev, "number of channels missing\n");
+		goto out;
+	}
+
+	rc = device_property_read_u32(&pdev->dev,
+				      "channel-reset-timeout-cycles",
+				      &mgmtdev->chreset_timeout_cycles);
+	if (rc) {
+		dev_err(&pdev->dev, "channel reset timeout missing\n");
+		goto out;
+	}
+
+	rc = device_property_read_u32(&pdev->dev, "max-write-burst-bytes",
+				      &mgmtdev->max_write_request);
+	if (rc) {
+		dev_err(&pdev->dev, "max-write-burst-bytes missing\n");
+		goto out;
+	}
+
+	rc = device_property_read_u32(&pdev->dev, "max-read-burst-bytes",
+				      &mgmtdev->max_read_request);
+	if (rc) {
+		dev_err(&pdev->dev, "max-read-burst-bytes missing\n");
+		goto out;
+	}
+
+	rc = device_property_read_u32(&pdev->dev, "max-write-transactions",
+				      &mgmtdev->max_wr_xactions);
+	if (rc) {
+		dev_err(&pdev->dev, "max-write-transactions missing\n");
+		goto out;
+	}
+
+	rc = device_property_read_u32(&pdev->dev, "max-read-transactions",
+				      &mgmtdev->max_rd_xactions);
+	if (rc) {
+		dev_err(&pdev->dev, "max-read-transactions missing\n");
+		goto out;
+	}
+
+	mgmtdev->priority = devm_kcalloc(&pdev->dev,
+					 mgmtdev->dma_channels,
+					 sizeof(*mgmtdev->priority),
+					 GFP_KERNEL);
+	if (!mgmtdev->priority) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	mgmtdev->weight = devm_kcalloc(&pdev->dev,
+				       mgmtdev->dma_channels,
+				       sizeof(*mgmtdev->weight), GFP_KERNEL);
+	if (!mgmtdev->weight) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	rc = hidma_mgmt_setup(mgmtdev);
+	if (rc) {
+		dev_err(&pdev->dev, "setup failed\n");
+		goto out;
+	}
+
+	/* start the HW */
+	val = readl(mgmtdev->virtaddr + HIDMA_CFG_OFFSET);
+	val |= 1;
+	writel(val, mgmtdev->virtaddr + HIDMA_CFG_OFFSET);
+
+	rc = hidma_mgmt_init_sys(mgmtdev);
+	if (rc) {
+		dev_err(&pdev->dev, "sysfs setup failed\n");
+		goto out;
+	}
+
+	dev_info(&pdev->dev,
+		 "HW rev: %d.%d @ %pa with %d physical channels\n",
+		 mgmtdev->hw_version_major, mgmtdev->hw_version_minor,
+		 &res->start, mgmtdev->dma_channels);
+
+	platform_set_drvdata(pdev, mgmtdev);
+	pm_runtime_mark_last_busy(&pdev->dev);
+	pm_runtime_put_autosuspend(&pdev->dev);
+	return 0;
+out:
+	pm_runtime_put_sync_suspend(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+	return rc;
+}
+
+#if IS_ENABLED(CONFIG_ACPI)
+static const struct acpi_device_id hidma_mgmt_acpi_ids[] = {
+	{"QCOM8060"},
+	{},
+};
+#endif
+
+static const struct of_device_id hidma_mgmt_match[] = {
+	{.compatible = "qcom,hidma-mgmt-1.0",},
+	{},
+};
+MODULE_DEVICE_TABLE(of, hidma_mgmt_match);
+
+static struct platform_driver hidma_mgmt_driver = {
+	.probe = hidma_mgmt_probe,
+	.driver = {
+		   .name = "hidma-mgmt",
+		   .of_match_table = hidma_mgmt_match,
+		   .acpi_match_table = ACPI_PTR(hidma_mgmt_acpi_ids),
+	},
+};
+
+module_platform_driver(hidma_mgmt_driver);
+MODULE_LICENSE("GPL v2");

drivers/dma/qcom/hidma_mgmt.h

+/*
+ * Qualcomm Technologies HIDMA Management common header
+ *
+ * Copyright (c) 2015, The Linux Foundation. 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 version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * 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.
+ */
+
+struct hidma_mgmt_dev {
+	u8 hw_version_major;
+	u8 hw_version_minor;
+
+	u32 max_wr_xactions;
+	u32 max_rd_xactions;
+	u32 max_write_request;
+	u32 max_read_request;
+	u32 dma_channels;
+	u32 chreset_timeout_cycles;
+	u32 hw_version;
+	u32 *priority;
+	u32 *weight;
+
+	/* Hardware device constants */
+	void __iomem *virtaddr;
+	resource_size_t addrsize;
+
+	struct kobject **chroots;
+	struct platform_device *pdev;
+};
+
+int hidma_mgmt_init_sys(struct hidma_mgmt_dev *dev);
+int hidma_mgmt_setup(struct hidma_mgmt_dev *mgmtdev);

drivers/dma/qcom/hidma_mgmt_sys.c

+/*
+ * Qualcomm Technologies HIDMA Management SYS interface
+ *
+ * Copyright (c) 2015, The Linux Foundation. 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 version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * 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.
+ */
+
+#include <linux/sysfs.h>
+#include <linux/platform_device.h>
+
+#include "hidma_mgmt.h"
+
+struct hidma_chan_attr {
+	struct hidma_mgmt_dev *mdev;
+	int index;
+	struct kobj_attribute attr;
+};
+
+struct hidma_mgmt_fileinfo {
+	char *name;
+	int mode;
+	int (*get)(struct hidma_mgmt_dev *mdev);
+	int (*set)(struct hidma_mgmt_dev *mdev, u64 val);
+};
+
+#define IMPLEMENT_GETSET(name)					\
+static int get_##name(struct hidma_mgmt_dev *mdev)		\
+{								\
+	return mdev->name;					\
+}								\
+static int set_##name(struct hidma_mgmt_dev *mdev, u64 val)	\
+{								\
+	u64 tmp;						\
+	int rc;							\
+								\
+	tmp = mdev->name;					\
+	mdev->name = val;					\
+	rc = hidma_mgmt_setup(mdev);				\
+	if (rc)							\
+		mdev->name = tmp;				\
+	return rc;						\
+}
+
+#define DECLARE_ATTRIBUTE(name, mode)				\
+	{#name, mode, get_##name, set_##name}
+
+IMPLEMENT_GETSET(hw_version_major)
+IMPLEMENT_GETSET(hw_version_minor)
+IMPLEMENT_GETSET(max_wr_xactions)
+IMPLEMENT_GETSET(max_rd_xactions)
+IMPLEMENT_GETSET(max_write_request)
+IMPLEMENT_GETSET(max_read_request)
+IMPLEMENT_GETSET(dma_channels)
+IMPLEMENT_GETSET(chreset_timeout_cycles)
+
+static int set_priority(struct hidma_mgmt_dev *mdev, unsigned int i, u64 val)
+{
+	u64 tmp;
+	int rc;
+
+	if (i >= mdev->dma_channels)
+		return -EINVAL;
+
+	tmp = mdev->priority[i];
+	mdev->priority[i] = val;
+	rc = hidma_mgmt_setup(mdev);
+	if (rc)
+		mdev->priority[i] = tmp;
+	return rc;
+}
+
+static int set_weight(struct hidma_mgmt_dev *mdev, unsigned int i, u64 val)
+{
+	u64 tmp;
+	int rc;
+
+	if (i >= mdev->dma_channels)
+		return -EINVAL;
+
+	tmp = mdev->weight[i];
+	mdev->weight[i] = val;
+	rc = hidma_mgmt_setup(mdev);
+	if (rc)
+		mdev->weight[i] = tmp;
+	return rc;
+}
+
+static struct hidma_mgmt_fileinfo hidma_mgmt_files[] = {
+	DECLARE_ATTRIBUTE(hw_version_major, S_IRUGO),
+	DECLARE_ATTRIBUTE(hw_version_minor, S_IRUGO),
+	DECLARE_ATTRIBUTE(dma_channels, S_IRUGO),
+	DECLARE_ATTRIBUTE(chreset_timeout_cycles, S_IRUGO),
+	DECLARE_ATTRIBUTE(max_wr_xactions, S_IRUGO),
+	DECLARE_ATTRIBUTE(max_rd_xactions, S_IRUGO),
+	DECLARE_ATTRIBUTE(max_write_request, S_IRUGO),
+	DECLARE_ATTRIBUTE(max_read_request, S_IRUGO),
+};
+
+static ssize_t show_values(struct device *dev, struct device_attribute *attr,
+			   char *buf)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct hidma_mgmt_dev *mdev = platform_get_drvdata(pdev);
+	unsigned int i;
+
+	buf[0] = 0;
+
+	for (i = 0; i < ARRAY_SIZE(hidma_mgmt_files); i++) {
+		if (strcmp(attr->attr.name, hidma_mgmt_files[i].name) == 0) {
+			sprintf(buf, "%d\n", hidma_mgmt_files[i].get(mdev));
+			break;
+		}
+	}
+	return strlen(buf);
+}
+
+static ssize_t set_values(struct device *dev, struct device_attribute *attr,
+			  const char *buf, size_t count)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct hidma_mgmt_dev *mdev = platform_get_drvdata(pdev);
+	unsigned long tmp;
+	unsigned int i;
+	int rc;
+
+	rc = kstrtoul(buf, 0, &tmp);
+	if (rc)
+		return rc;
+
+	for (i = 0; i < ARRAY_SIZE(hidma_mgmt_files); i++) {
+		if (strcmp(attr->attr.name, hidma_mgmt_files[i].name) == 0) {
+			rc = hidma_mgmt_files[i].set(mdev, tmp);
+			if (rc)
+				return rc;
+
+			break;
+		}
+	}
+	return count;
+}
+
+static ssize_t show_values_channel(struct kobject *kobj,
+				   struct kobj_attribute *attr, char *buf)
+{
+	struct hidma_chan_attr *chattr;
+	struct hidma_mgmt_dev *mdev;
+
+	buf[0] = 0;
+	chattr = container_of(attr, struct hidma_chan_attr, attr);
+	mdev = chattr->mdev;
+	if (strcmp(attr->attr.name, "priority") == 0)
+		sprintf(buf, "%d\n", mdev->priority[chattr->index]);
+	else if (strcmp(attr->attr.name, "weight") == 0)
+		sprintf(buf, "%d\n", mdev->weight[chattr->index]);
+
+	return strlen(buf);
+}
+
+static ssize_t set_values_channel(struct kobject *kobj,
+				  struct kobj_attribute *attr, const char *buf,
+				  size_t count)
+{
+	struct hidma_chan_attr *chattr;
+	struct hidma_mgmt_dev *mdev;
+	unsigned long tmp;
+	int rc;
+
+	chattr = container_of(attr, struct hidma_chan_attr, attr);
+	mdev = chattr->mdev;
+
+	rc = kstrtoul(buf, 0, &tmp);
+	if (rc)
+		return rc;
+
+	if (strcmp(attr->attr.name, "priority") == 0) {
+		rc = set_priority(mdev, chattr->index, tmp);
+		if (rc)
+			return rc;
+	} else if (strcmp(attr->attr.name, "weight") == 0) {
+		rc = set_weight(mdev, chattr->index, tmp);
+		if (rc)
+			return rc;
+	}
+	return count;
+}
+
+static int create_sysfs_entry(struct hidma_mgmt_dev *dev, char *name, int mode)
+{
+	struct device_attribute *attrs;
+	char *name_copy;
+
+	attrs = devm_kmalloc(&dev->pdev->dev,
+			     sizeof(struct device_attribute), GFP_KERNEL);
+	if (!attrs)
+		return -ENOMEM;
+
+	name_copy = devm_kstrdup(&dev->pdev->dev, name, GFP_KERNEL);
+	if (!name_copy)
+		return -ENOMEM;
+
+	attrs->attr.name = name_copy;
+	attrs->attr.mode = mode;
+	attrs->show = show_values;
+	attrs->store = set_values;
+	sysfs_attr_init(&attrs->attr);
+
+	return device_create_file(&dev->pdev->dev, attrs);
+}
+
+static int create_sysfs_entry_channel(struct hidma_mgmt_dev *mdev, char *name,
+				      int mode, int index,
+				      struct kobject *parent)
+{
+	struct hidma_chan_attr *chattr;
+	char *name_copy;
+
+	chattr = devm_kmalloc(&mdev->pdev->dev, sizeof(*chattr), GFP_KERNEL);
+	if (!chattr)
+		return -ENOMEM;
+
+	name_copy = devm_kstrdup(&mdev->pdev->dev, name, GFP_KERNEL);
+	if (!name_copy)
+		return -ENOMEM;
+
+	chattr->mdev = mdev;
+	chattr->index = index;
+	chattr->attr.attr.name = name_copy;
+	chattr->attr.attr.mode = mode;
+	chattr->attr.show = show_values_channel;
+	chattr->attr.store = set_values_channel;
+	sysfs_attr_init(&chattr->attr.attr);
+
+	return sysfs_create_file(parent, &chattr->attr.attr);
+}
+
+int hidma_mgmt_init_sys(struct hidma_mgmt_dev *mdev)
+{
+	unsigned int i;
+	int rc;
+	int required;
+	struct kobject *chanops;
+
+	required = sizeof(*mdev->chroots) * mdev->dma_channels;
+	mdev->chroots = devm_kmalloc(&mdev->pdev->dev, required, GFP_KERNEL);
+	if (!mdev->chroots)
+		return -ENOMEM;
+
+	chanops = kobject_create_and_add("chanops", &mdev->pdev->dev.kobj);
+	if (!chanops)
+		return -ENOMEM;
+
+	/* create each channel directory here */
+	for (i = 0; i < mdev->dma_channels; i++) {
+		char name[20];
+
+		snprintf(name, sizeof(name), "chan%d", i);
+		mdev->chroots[i] = kobject_create_and_add(name, chanops);
+		if (!mdev->chroots[i])
+			return -ENOMEM;
+	}
+
+	/* populate common parameters */
+	for (i = 0; i < ARRAY_SIZE(hidma_mgmt_files); i++) {
+		rc = create_sysfs_entry(mdev, hidma_mgmt_files[i].name,
+					hidma_mgmt_files[i].mode);
+		if (rc)
+			return rc;
+	}
+
+	/* populate parameters that are per channel */
+	for (i = 0; i < mdev->dma_channels; i++) {
+		rc = create_sysfs_entry_channel(mdev, "priority",
+						(S_IRUGO | S_IWUGO), i,
+						mdev->chroots[i]);
+		if (rc)
+			return rc;
+
+		rc = create_sysfs_entry_channel(mdev, "weight",
+						(S_IRUGO | S_IWUGO), i,
+						mdev->chroots[i]);
+		if (rc)
+			return rc;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(hidma_mgmt_init_sys);