drivers/memory/mvebu-devbus.c - kernel/msm-4.9 - Gitiles

 /*
  * Marvell EBU SoC Device Bus Controller
  * (memory controller for NOR/NAND/SRAM/FPGA devices)
  *
  * Copyright (C) 2013-2014 Marvell
  *
  * 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 version 2 of the License.
  *
  * 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, see <http://www.gnu.org/licenses/>.
  *
  */

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/clk.h>
 #include <linux/mbus.h>
 #include <linux/of_platform.h>
 #include <linux/of_address.h>
 #include <linux/platform_device.h>

 /* Register definitions */
 #define ARMADA_DEV_WIDTH_SHIFT		30
 #define ARMADA_BADR_SKEW_SHIFT		28
 #define ARMADA_RD_HOLD_SHIFT		23
 #define ARMADA_ACC_NEXT_SHIFT		17
 #define ARMADA_RD_SETUP_SHIFT		12
 #define ARMADA_ACC_FIRST_SHIFT		6

 #define ARMADA_SYNC_ENABLE_SHIFT	24
 #define ARMADA_WR_HIGH_SHIFT		16
 #define ARMADA_WR_LOW_SHIFT		8

 #define ARMADA_READ_PARAM_OFFSET	0x0
 #define ARMADA_WRITE_PARAM_OFFSET	0x4

 #define ORION_RESERVED			(0x2 << 30)
 #define ORION_BADR_SKEW_SHIFT		28
 #define ORION_WR_HIGH_EXT_BIT		BIT(27)
 #define ORION_WR_HIGH_EXT_MASK		0x8
 #define ORION_WR_LOW_EXT_BIT		BIT(26)
 #define ORION_WR_LOW_EXT_MASK		0x8
 #define ORION_ALE_WR_EXT_BIT		BIT(25)
 #define ORION_ALE_WR_EXT_MASK		0x8
 #define ORION_ACC_NEXT_EXT_BIT		BIT(24)
 #define ORION_ACC_NEXT_EXT_MASK		0x10
 #define ORION_ACC_FIRST_EXT_BIT		BIT(23)
 #define ORION_ACC_FIRST_EXT_MASK	0x10
 #define ORION_TURN_OFF_EXT_BIT		BIT(22)
 #define ORION_TURN_OFF_EXT_MASK		0x8
 #define ORION_DEV_WIDTH_SHIFT		20
 #define ORION_WR_HIGH_SHIFT		17
 #define ORION_WR_HIGH_MASK		0x7
 #define ORION_WR_LOW_SHIFT		14
 #define ORION_WR_LOW_MASK		0x7
 #define ORION_ALE_WR_SHIFT		11
 #define ORION_ALE_WR_MASK		0x7
 #define ORION_ACC_NEXT_SHIFT		7
 #define ORION_ACC_NEXT_MASK		0xF
 #define ORION_ACC_FIRST_SHIFT		3
 #define ORION_ACC_FIRST_MASK		0xF
 #define ORION_TURN_OFF_SHIFT		0
 #define ORION_TURN_OFF_MASK		0x7

 struct devbus_read_params {
 	u32 bus_width;
 	u32 badr_skew;
 	u32 turn_off;
 	u32 acc_first;
 	u32 acc_next;
 	u32 rd_setup;
 	u32 rd_hold;
 };

 struct devbus_write_params {
 	u32 sync_enable;
 	u32 wr_high;
 	u32 wr_low;
 	u32 ale_wr;
 };

 struct devbus {
 	struct device *dev;
 	void __iomem *base;
 	unsigned long tick_ps;
 };

 static int get_timing_param_ps(struct devbus *devbus,
 			       struct device_node *node,
 			       const char *name,
 			       u32 *ticks)
 {
 	u32 time_ps;
 	int err;

 	err = of_property_read_u32(node, name, &time_ps);
 	if (err < 0) {
 		dev_err(devbus->dev, "%s has no '%s' property\n",
 			name, node->full_name);
 		return err;
 	}

 	*ticks = (time_ps + devbus->tick_ps - 1) / devbus->tick_ps;

 	dev_dbg(devbus->dev, "%s: %u ps -> 0x%x\n",
 		name, time_ps, *ticks);
 	return 0;
 }

 static int devbus_get_timing_params(struct devbus *devbus,
 				    struct device_node *node,
 				    struct devbus_read_params *r,
 				    struct devbus_write_params *w)
 {
 	int err;

 	err = of_property_read_u32(node, "devbus,bus-width", &r->bus_width);
 	if (err < 0) {
 		dev_err(devbus->dev,
 			"%s has no 'devbus,bus-width' property\n",
 			node->full_name);
 		return err;
 	}

 	/*
 	 * The bus width is encoded into the register as 0 for 8 bits,
 	 * and 1 for 16 bits, so we do the necessary conversion here.
 	 */
 	if (r->bus_width == 8)
 		r->bus_width = 0;
 	else if (r->bus_width == 16)
 		r->bus_width = 1;
 	else {
 		dev_err(devbus->dev, "invalid bus width %d\n", r->bus_width);
 		return -EINVAL;
 	}

 	err = get_timing_param_ps(devbus, node, "devbus,badr-skew-ps",
 				 &r->badr_skew);
 	if (err < 0)
 		return err;

 	err = get_timing_param_ps(devbus, node, "devbus,turn-off-ps",
 				 &r->turn_off);
 	if (err < 0)
 		return err;

 	err = get_timing_param_ps(devbus, node, "devbus,acc-first-ps",
 				 &r->acc_first);
 	if (err < 0)
 		return err;

 	err = get_timing_param_ps(devbus, node, "devbus,acc-next-ps",
 				 &r->acc_next);
 	if (err < 0)
 		return err;

 	if (of_device_is_compatible(devbus->dev->of_node, "marvell,mvebu-devbus")) {
 		err = get_timing_param_ps(devbus, node, "devbus,rd-setup-ps",
 					  &r->rd_setup);
 		if (err < 0)
 			return err;

 		err = get_timing_param_ps(devbus, node, "devbus,rd-hold-ps",
 					  &r->rd_hold);
 		if (err < 0)
 			return err;

 		err = of_property_read_u32(node, "devbus,sync-enable",
 					   &w->sync_enable);
 		if (err < 0) {
 			dev_err(devbus->dev,
 				"%s has no 'devbus,sync-enable' property\n",
 				node->full_name);
 			return err;
 		}
 	}

 	err = get_timing_param_ps(devbus, node, "devbus,ale-wr-ps",
 				 &w->ale_wr);
 	if (err < 0)
 		return err;

 	err = get_timing_param_ps(devbus, node, "devbus,wr-low-ps",
 				 &w->wr_low);
 	if (err < 0)
 		return err;

 	err = get_timing_param_ps(devbus, node, "devbus,wr-high-ps",
 				 &w->wr_high);
 	if (err < 0)
 		return err;

 	return 0;
 }

 static void devbus_orion_set_timing_params(struct devbus *devbus,
 					  struct device_node *node,
 					  struct devbus_read_params *r,
 					  struct devbus_write_params *w)
 {
 	u32 value;

 	/*
 	 * The hardware designers found it would be a good idea to
 	 * split most of the values in the register into two fields:
 	 * one containing all the low-order bits, and another one
 	 * containing just the high-order bit. For all of those
 	 * fields, we have to split the value into these two parts.
 	 */
 	value =	(r->turn_off   & ORION_TURN_OFF_MASK)  << ORION_TURN_OFF_SHIFT  |
 		(r->acc_first  & ORION_ACC_FIRST_MASK) << ORION_ACC_FIRST_SHIFT |
 		(r->acc_next   & ORION_ACC_NEXT_MASK)  << ORION_ACC_NEXT_SHIFT  |
 		(w->ale_wr     & ORION_ALE_WR_MASK)    << ORION_ALE_WR_SHIFT    |
 		(w->wr_low     & ORION_WR_LOW_MASK)    << ORION_WR_LOW_SHIFT    |
 		(w->wr_high    & ORION_WR_HIGH_MASK)   << ORION_WR_HIGH_SHIFT   |
 		r->bus_width                           << ORION_DEV_WIDTH_SHIFT |
 		((r->turn_off  & ORION_TURN_OFF_EXT_MASK)  ? ORION_TURN_OFF_EXT_BIT  : 0) |
 		((r->acc_first & ORION_ACC_FIRST_EXT_MASK) ? ORION_ACC_FIRST_EXT_BIT : 0) |
 		((r->acc_next  & ORION_ACC_NEXT_EXT_MASK)  ? ORION_ACC_NEXT_EXT_BIT  : 0) |
 		((w->ale_wr    & ORION_ALE_WR_EXT_MASK)    ? ORION_ALE_WR_EXT_BIT    : 0) |
 		((w->wr_low    & ORION_WR_LOW_EXT_MASK)    ? ORION_WR_LOW_EXT_BIT    : 0) |
 		((w->wr_high   & ORION_WR_HIGH_EXT_MASK)   ? ORION_WR_HIGH_EXT_BIT   : 0) |
 		(r->badr_skew << ORION_BADR_SKEW_SHIFT) |
 		ORION_RESERVED;

 	writel(value, devbus->base);
 }

 static void devbus_armada_set_timing_params(struct devbus *devbus,
 					   struct device_node *node,
 					   struct devbus_read_params *r,
 					   struct devbus_write_params *w)
 {
 	u32 value;

 	/* Set read timings */
 	value = r->bus_width << ARMADA_DEV_WIDTH_SHIFT |
 		r->badr_skew << ARMADA_BADR_SKEW_SHIFT |
 		r->rd_hold   << ARMADA_RD_HOLD_SHIFT   |
 		r->acc_next  << ARMADA_ACC_NEXT_SHIFT  |
 		r->rd_setup  << ARMADA_RD_SETUP_SHIFT  |
 		r->acc_first << ARMADA_ACC_FIRST_SHIFT |
 		r->turn_off;

 	dev_dbg(devbus->dev, "read parameters register 0x%p = 0x%x\n",
 		devbus->base + ARMADA_READ_PARAM_OFFSET,
 		value);

 	writel(value, devbus->base + ARMADA_READ_PARAM_OFFSET);

 	/* Set write timings */
 	value = w->sync_enable  << ARMADA_SYNC_ENABLE_SHIFT |
 		w->wr_low       << ARMADA_WR_LOW_SHIFT      |
 		w->wr_high      << ARMADA_WR_HIGH_SHIFT     |
 		w->ale_wr;

 	dev_dbg(devbus->dev, "write parameters register: 0x%p = 0x%x\n",
 		devbus->base + ARMADA_WRITE_PARAM_OFFSET,
 		value);

 	writel(value, devbus->base + ARMADA_WRITE_PARAM_OFFSET);
 }

 static int mvebu_devbus_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct device_node *node = pdev->dev.of_node;
 	struct devbus_read_params r;
 	struct devbus_write_params w;
 	struct devbus *devbus;
 	struct resource *res;
 	struct clk *clk;
 	unsigned long rate;
 	int err;

 	devbus = devm_kzalloc(&pdev->dev, sizeof(struct devbus), GFP_KERNEL);
 	if (!devbus)
 		return -ENOMEM;

 	devbus->dev = dev;
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	devbus->base = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(devbus->base))
 		return PTR_ERR(devbus->base);

 	clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(clk))
 		return PTR_ERR(clk);
 	clk_prepare_enable(clk);

 	/*
 	 * Obtain clock period in picoseconds,
 	 * we need this in order to convert timing
 	 * parameters from cycles to picoseconds.
 	 */
 	rate = clk_get_rate(clk) / 1000;
 	devbus->tick_ps = 1000000000 / rate;

 	dev_dbg(devbus->dev, "Setting timing parameter, tick is %lu ps\n",
 		devbus->tick_ps);

 	if (!of_property_read_bool(node, "devbus,keep-config")) {
 		/* Read the Device Tree node */
 		err = devbus_get_timing_params(devbus, node, &r, &w);
 		if (err < 0)
 			return err;

 		/* Set the new timing parameters */
 		if (of_device_is_compatible(node, "marvell,orion-devbus"))
 			devbus_orion_set_timing_params(devbus, node, &r, &w);
 		else
 			devbus_armada_set_timing_params(devbus, node, &r, &w);
 	}

 	/*
 	 * We need to create a child device explicitly from here to
 	 * guarantee that the child will be probed after the timing
 	 * parameters for the bus are written.
 	 */
 	err = of_platform_populate(node, NULL, NULL, dev);
 	if (err < 0)
 		return err;

 	return 0;
 }

 static const struct of_device_id mvebu_devbus_of_match[] = {
 	{ .compatible = "marvell,mvebu-devbus" },
 	{ .compatible = "marvell,orion-devbus" },
 	{},
 };
 MODULE_DEVICE_TABLE(of, mvebu_devbus_of_match);

 static struct platform_driver mvebu_devbus_driver = {
 	.probe		= mvebu_devbus_probe,
 	.driver		= {
 		.name	= "mvebu-devbus",
 		.of_match_table = mvebu_devbus_of_match,
 	},
 };

 static int __init mvebu_devbus_init(void)
 {
 	return platform_driver_register(&mvebu_devbus_driver);
 }
 module_init(mvebu_devbus_init);

 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Ezequiel Garcia <ezequiel.garcia@free-electrons.com>");
 MODULE_DESCRIPTION("Marvell EBU SoC Device Bus controller");
	/*
	* Marvell EBU SoC Device Bus Controller
	* (memory controller for NOR/NAND/SRAM/FPGA devices)
	*
	* Copyright (C) 2013-2014 Marvell
	*
	* 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 version 2 of the License.
	*
	* 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, see <http://www.gnu.org/licenses/>.
	*
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/err.h>
	#include <linux/io.h>
	#include <linux/clk.h>
	#include <linux/mbus.h>
	#include <linux/of_platform.h>
	#include <linux/of_address.h>
	#include <linux/platform_device.h>

	/* Register definitions */
	#define ARMADA_DEV_WIDTH_SHIFT 30
	#define ARMADA_BADR_SKEW_SHIFT 28
	#define ARMADA_RD_HOLD_SHIFT 23
	#define ARMADA_ACC_NEXT_SHIFT 17
	#define ARMADA_RD_SETUP_SHIFT 12
	#define ARMADA_ACC_FIRST_SHIFT 6

	#define ARMADA_SYNC_ENABLE_SHIFT 24
	#define ARMADA_WR_HIGH_SHIFT 16
	#define ARMADA_WR_LOW_SHIFT 8

	#define ARMADA_READ_PARAM_OFFSET 0x0
	#define ARMADA_WRITE_PARAM_OFFSET 0x4

	#define ORION_RESERVED (0x2 << 30)
	#define ORION_BADR_SKEW_SHIFT 28
	#define ORION_WR_HIGH_EXT_BIT BIT(27)
	#define ORION_WR_HIGH_EXT_MASK 0x8
	#define ORION_WR_LOW_EXT_BIT BIT(26)
	#define ORION_WR_LOW_EXT_MASK 0x8
	#define ORION_ALE_WR_EXT_BIT BIT(25)
	#define ORION_ALE_WR_EXT_MASK 0x8
	#define ORION_ACC_NEXT_EXT_BIT BIT(24)
	#define ORION_ACC_NEXT_EXT_MASK 0x10
	#define ORION_ACC_FIRST_EXT_BIT BIT(23)
	#define ORION_ACC_FIRST_EXT_MASK 0x10
	#define ORION_TURN_OFF_EXT_BIT BIT(22)
	#define ORION_TURN_OFF_EXT_MASK 0x8
	#define ORION_DEV_WIDTH_SHIFT 20
	#define ORION_WR_HIGH_SHIFT 17
	#define ORION_WR_HIGH_MASK 0x7
	#define ORION_WR_LOW_SHIFT 14
	#define ORION_WR_LOW_MASK 0x7
	#define ORION_ALE_WR_SHIFT 11
	#define ORION_ALE_WR_MASK 0x7
	#define ORION_ACC_NEXT_SHIFT 7
	#define ORION_ACC_NEXT_MASK 0xF
	#define ORION_ACC_FIRST_SHIFT 3
	#define ORION_ACC_FIRST_MASK 0xF
	#define ORION_TURN_OFF_SHIFT 0
	#define ORION_TURN_OFF_MASK 0x7

	struct devbus_read_params {
	u32 bus_width;
	u32 badr_skew;
	u32 turn_off;
	u32 acc_first;
	u32 acc_next;
	u32 rd_setup;
	u32 rd_hold;
	};

	struct devbus_write_params {
	u32 sync_enable;
	u32 wr_high;
	u32 wr_low;
	u32 ale_wr;
	};

	struct devbus {
	struct device *dev;
	void __iomem *base;
	unsigned long tick_ps;
	};

	static int get_timing_param_ps(struct devbus *devbus,
	struct device_node *node,
	const char *name,
	u32 *ticks)
	{
	u32 time_ps;
	int err;

	err = of_property_read_u32(node, name, &time_ps);
	if (err < 0) {
	dev_err(devbus->dev, "%s has no '%s' property\n",
	name, node->full_name);
	return err;
	}

	*ticks = (time_ps + devbus->tick_ps - 1) / devbus->tick_ps;

	dev_dbg(devbus->dev, "%s: %u ps -> 0x%x\n",
	name, time_ps, *ticks);
	return 0;
	}

	static int devbus_get_timing_params(struct devbus *devbus,
	struct device_node *node,
	struct devbus_read_params *r,
	struct devbus_write_params *w)
	{
	int err;

	err = of_property_read_u32(node, "devbus,bus-width", &r->bus_width);
	if (err < 0) {
	dev_err(devbus->dev,
	"%s has no 'devbus,bus-width' property\n",
	node->full_name);
	return err;
	}

	/*
	* The bus width is encoded into the register as 0 for 8 bits,
	* and 1 for 16 bits, so we do the necessary conversion here.
	*/
	if (r->bus_width == 8)
	r->bus_width = 0;
	else if (r->bus_width == 16)
	r->bus_width = 1;
	else {
	dev_err(devbus->dev, "invalid bus width %d\n", r->bus_width);
	return -EINVAL;
	}

	err = get_timing_param_ps(devbus, node, "devbus,badr-skew-ps",
	&r->badr_skew);
	if (err < 0)
	return err;

	err = get_timing_param_ps(devbus, node, "devbus,turn-off-ps",
	&r->turn_off);
	if (err < 0)
	return err;

	err = get_timing_param_ps(devbus, node, "devbus,acc-first-ps",
	&r->acc_first);
	if (err < 0)
	return err;

	err = get_timing_param_ps(devbus, node, "devbus,acc-next-ps",
	&r->acc_next);
	if (err < 0)
	return err;

	if (of_device_is_compatible(devbus->dev->of_node, "marvell,mvebu-devbus")) {
	err = get_timing_param_ps(devbus, node, "devbus,rd-setup-ps",
	&r->rd_setup);
	if (err < 0)
	return err;

	err = get_timing_param_ps(devbus, node, "devbus,rd-hold-ps",
	&r->rd_hold);
	if (err < 0)
	return err;

	err = of_property_read_u32(node, "devbus,sync-enable",
	&w->sync_enable);
	if (err < 0) {
	dev_err(devbus->dev,
	"%s has no 'devbus,sync-enable' property\n",
	node->full_name);
	return err;
	}
	}

	err = get_timing_param_ps(devbus, node, "devbus,ale-wr-ps",
	&w->ale_wr);
	if (err < 0)
	return err;

	err = get_timing_param_ps(devbus, node, "devbus,wr-low-ps",
	&w->wr_low);
	if (err < 0)
	return err;

	err = get_timing_param_ps(devbus, node, "devbus,wr-high-ps",
	&w->wr_high);
	if (err < 0)
	return err;

	return 0;
	}

	static void devbus_orion_set_timing_params(struct devbus *devbus,
	struct device_node *node,
	struct devbus_read_params *r,
	struct devbus_write_params *w)
	{
	u32 value;

	/*
	* The hardware designers found it would be a good idea to
	* split most of the values in the register into two fields:
	* one containing all the low-order bits, and another one
	* containing just the high-order bit. For all of those
	* fields, we have to split the value into these two parts.
	*/
	value = (r->turn_off & ORION_TURN_OFF_MASK) << ORION_TURN_OFF_SHIFT \|
	(r->acc_first & ORION_ACC_FIRST_MASK) << ORION_ACC_FIRST_SHIFT \|
	(r->acc_next & ORION_ACC_NEXT_MASK) << ORION_ACC_NEXT_SHIFT \|
	(w->ale_wr & ORION_ALE_WR_MASK) << ORION_ALE_WR_SHIFT \|
	(w->wr_low & ORION_WR_LOW_MASK) << ORION_WR_LOW_SHIFT \|
	(w->wr_high & ORION_WR_HIGH_MASK) << ORION_WR_HIGH_SHIFT \|
	r->bus_width << ORION_DEV_WIDTH_SHIFT \|
	((r->turn_off & ORION_TURN_OFF_EXT_MASK) ? ORION_TURN_OFF_EXT_BIT : 0) \|
	((r->acc_first & ORION_ACC_FIRST_EXT_MASK) ? ORION_ACC_FIRST_EXT_BIT : 0) \|
	((r->acc_next & ORION_ACC_NEXT_EXT_MASK) ? ORION_ACC_NEXT_EXT_BIT : 0) \|
	((w->ale_wr & ORION_ALE_WR_EXT_MASK) ? ORION_ALE_WR_EXT_BIT : 0) \|
	((w->wr_low & ORION_WR_LOW_EXT_MASK) ? ORION_WR_LOW_EXT_BIT : 0) \|
	((w->wr_high & ORION_WR_HIGH_EXT_MASK) ? ORION_WR_HIGH_EXT_BIT : 0) \|
	(r->badr_skew << ORION_BADR_SKEW_SHIFT) \|
	ORION_RESERVED;

	writel(value, devbus->base);
	}

	static void devbus_armada_set_timing_params(struct devbus *devbus,
	struct device_node *node,
	struct devbus_read_params *r,
	struct devbus_write_params *w)
	{
	u32 value;

	/* Set read timings */
	value = r->bus_width << ARMADA_DEV_WIDTH_SHIFT \|
	r->badr_skew << ARMADA_BADR_SKEW_SHIFT \|
	r->rd_hold << ARMADA_RD_HOLD_SHIFT \|
	r->acc_next << ARMADA_ACC_NEXT_SHIFT \|
	r->rd_setup << ARMADA_RD_SETUP_SHIFT \|
	r->acc_first << ARMADA_ACC_FIRST_SHIFT \|
	r->turn_off;

	dev_dbg(devbus->dev, "read parameters register 0x%p = 0x%x\n",
	devbus->base + ARMADA_READ_PARAM_OFFSET,
	value);

	writel(value, devbus->base + ARMADA_READ_PARAM_OFFSET);

	/* Set write timings */
	value = w->sync_enable << ARMADA_SYNC_ENABLE_SHIFT \|
	w->wr_low << ARMADA_WR_LOW_SHIFT \|
	w->wr_high << ARMADA_WR_HIGH_SHIFT \|
	w->ale_wr;

	dev_dbg(devbus->dev, "write parameters register: 0x%p = 0x%x\n",
	devbus->base + ARMADA_WRITE_PARAM_OFFSET,
	value);

	writel(value, devbus->base + ARMADA_WRITE_PARAM_OFFSET);
	}

	static int mvebu_devbus_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct device_node *node = pdev->dev.of_node;
	struct devbus_read_params r;
	struct devbus_write_params w;
	struct devbus *devbus;
	struct resource *res;
	struct clk *clk;
	unsigned long rate;
	int err;

	devbus = devm_kzalloc(&pdev->dev, sizeof(struct devbus), GFP_KERNEL);
	if (!devbus)
	return -ENOMEM;

	devbus->dev = dev;
	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	devbus->base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(devbus->base))
	return PTR_ERR(devbus->base);

	clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(clk))
	return PTR_ERR(clk);
	clk_prepare_enable(clk);

	/*
	* Obtain clock period in picoseconds,
	* we need this in order to convert timing
	* parameters from cycles to picoseconds.
	*/
	rate = clk_get_rate(clk) / 1000;
	devbus->tick_ps = 1000000000 / rate;

	dev_dbg(devbus->dev, "Setting timing parameter, tick is %lu ps\n",
	devbus->tick_ps);

	if (!of_property_read_bool(node, "devbus,keep-config")) {
	/* Read the Device Tree node */
	err = devbus_get_timing_params(devbus, node, &r, &w);
	if (err < 0)
	return err;

	/* Set the new timing parameters */
	if (of_device_is_compatible(node, "marvell,orion-devbus"))
	devbus_orion_set_timing_params(devbus, node, &r, &w);
	else
	devbus_armada_set_timing_params(devbus, node, &r, &w);
	}

	/*
	* We need to create a child device explicitly from here to
	* guarantee that the child will be probed after the timing
	* parameters for the bus are written.
	*/
	err = of_platform_populate(node, NULL, NULL, dev);
	if (err < 0)
	return err;

	return 0;
	}

	static const struct of_device_id mvebu_devbus_of_match[] = {
	{ .compatible = "marvell,mvebu-devbus" },
	{ .compatible = "marvell,orion-devbus" },
	{},
	};
	MODULE_DEVICE_TABLE(of, mvebu_devbus_of_match);

	static struct platform_driver mvebu_devbus_driver = {
	.probe = mvebu_devbus_probe,
	.driver = {
	.name = "mvebu-devbus",
	.of_match_table = mvebu_devbus_of_match,
	},
	};

	static int __init mvebu_devbus_init(void)
	{
	return platform_driver_register(&mvebu_devbus_driver);
	}
	module_init(mvebu_devbus_init);

	MODULE_LICENSE("GPL v2");
	MODULE_AUTHOR("Ezequiel Garcia <ezequiel.garcia@free-electrons.com>");
	MODULE_DESCRIPTION("Marvell EBU SoC Device Bus controller");