drivers/bus/vexpress-config.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  *
  * Copyright (C) 2014 ARM Limited
  */

 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/of_platform.h>
 #include <linux/sched/signal.h>
 #include <linux/slab.h>
 #include <linux/vexpress.h>

 #define SYS_MISC		0x0
 #define SYS_MISC_MASTERSITE	(1 << 14)

 #define SYS_PROCID0		0x24
 #define SYS_PROCID1		0x28
 #define SYS_HBI_MASK		0xfff
 #define SYS_PROCIDx_HBI_SHIFT	0

 #define SYS_CFGDATA		0x40

 #define SYS_CFGCTRL		0x44
 #define SYS_CFGCTRL_START	(1 << 31)
 #define SYS_CFGCTRL_WRITE	(1 << 30)
 #define SYS_CFGCTRL_DCC(n)	(((n) & 0xf) << 26)
 #define SYS_CFGCTRL_FUNC(n)	(((n) & 0x3f) << 20)
 #define SYS_CFGCTRL_SITE(n)	(((n) & 0x3) << 16)
 #define SYS_CFGCTRL_POSITION(n)	(((n) & 0xf) << 12)
 #define SYS_CFGCTRL_DEVICE(n)	(((n) & 0xfff) << 0)

 #define SYS_CFGSTAT		0x48
 #define SYS_CFGSTAT_ERR		(1 << 1)
 #define SYS_CFGSTAT_COMPLETE	(1 << 0)

 #define VEXPRESS_SITE_MB		0
 #define VEXPRESS_SITE_DB1		1
 #define VEXPRESS_SITE_DB2		2
 #define VEXPRESS_SITE_MASTER		0xf

 struct vexpress_syscfg {
 	struct device *dev;
 	void __iomem *base;
 	struct list_head funcs;
 };

 struct vexpress_syscfg_func {
 	struct list_head list;
 	struct vexpress_syscfg *syscfg;
 	struct regmap *regmap;
 	int num_templates;
 	u32 template[] __counted_by(num_templates); /* Keep it last! */
 };

 struct vexpress_config_bridge_ops {
 	struct regmap * (*regmap_init)(struct device *dev, void *context);
 	void (*regmap_exit)(struct regmap *regmap, void *context);
 };

 struct vexpress_config_bridge {
 	struct vexpress_config_bridge_ops *ops;
 	void *context;
 };


 static DEFINE_MUTEX(vexpress_config_mutex);
 static u32 vexpress_config_site_master = VEXPRESS_SITE_MASTER;


 static void vexpress_config_set_master(u32 site)
 {
 	vexpress_config_site_master = site;
 }

 static void vexpress_config_lock(void *arg)
 {
 	mutex_lock(&vexpress_config_mutex);
 }

 static void vexpress_config_unlock(void *arg)
 {
 	mutex_unlock(&vexpress_config_mutex);
 }


 static void vexpress_config_find_prop(struct device_node *node,
 		const char *name, u32 *val)
 {
 	/* Default value */
 	*val = 0;

 	of_node_get(node);
 	while (node) {
 		if (of_property_read_u32(node, name, val) == 0) {
 			of_node_put(node);
 			return;
 		}
 		node = of_get_next_parent(node);
 	}
 }

 static int vexpress_config_get_topo(struct device_node *node, u32 *site,
 		u32 *position, u32 *dcc)
 {
 	vexpress_config_find_prop(node, "arm,vexpress,site", site);
 	if (*site == VEXPRESS_SITE_MASTER)
 		*site = vexpress_config_site_master;
 	if (WARN_ON(vexpress_config_site_master == VEXPRESS_SITE_MASTER))
 		return -EINVAL;
 	vexpress_config_find_prop(node, "arm,vexpress,position", position);
 	vexpress_config_find_prop(node, "arm,vexpress,dcc", dcc);

 	return 0;
 }


 static void vexpress_config_devres_release(struct device *dev, void *res)
 {
 	struct vexpress_config_bridge *bridge = dev_get_drvdata(dev->parent);
 	struct regmap *regmap = res;

 	bridge->ops->regmap_exit(regmap, bridge->context);
 }

 struct regmap *devm_regmap_init_vexpress_config(struct device *dev)
 {
 	struct vexpress_config_bridge *bridge;
 	struct regmap *regmap;
 	struct regmap **res;

 	bridge = dev_get_drvdata(dev->parent);
 	if (WARN_ON(!bridge))
 		return ERR_PTR(-EINVAL);

 	res = devres_alloc(vexpress_config_devres_release, sizeof(*res),
 			GFP_KERNEL);
 	if (!res)
 		return ERR_PTR(-ENOMEM);

 	regmap = (bridge->ops->regmap_init)(dev, bridge->context);
 	if (IS_ERR(regmap)) {
 		devres_free(res);
 		return regmap;
 	}

 	*res = regmap;
 	devres_add(dev, res);

 	return regmap;
 }
 EXPORT_SYMBOL_GPL(devm_regmap_init_vexpress_config);

 static int vexpress_syscfg_exec(struct vexpress_syscfg_func *func,
 		int index, bool write, u32 *data)
 {
 	struct vexpress_syscfg *syscfg = func->syscfg;
 	u32 command, status;
 	int tries;
 	long timeout;

 	if (WARN_ON(index >= func->num_templates))
 		return -EINVAL;

 	command = readl(syscfg->base + SYS_CFGCTRL);
 	if (WARN_ON(command & SYS_CFGCTRL_START))
 		return -EBUSY;

 	command = func->template[index];
 	command |= SYS_CFGCTRL_START;
 	command |= write ? SYS_CFGCTRL_WRITE : 0;

 	/* Use a canary for reads */
 	if (!write)
 		*data = 0xdeadbeef;

 	dev_dbg(syscfg->dev, "func %p, command %x, data %x\n",
 			func, command, *data);
 	writel(*data, syscfg->base + SYS_CFGDATA);
 	writel(0, syscfg->base + SYS_CFGSTAT);
 	writel(command, syscfg->base + SYS_CFGCTRL);
 	mb();

 	/* The operation can take ages... Go to sleep, 100us initially */
 	tries = 100;
 	timeout = 100;
 	do {
 		if (!irqs_disabled()) {
 			set_current_state(TASK_INTERRUPTIBLE);
 			schedule_timeout(usecs_to_jiffies(timeout));
 			if (signal_pending(current))
 				return -EINTR;
 		} else {
 			udelay(timeout);
 		}

 		status = readl(syscfg->base + SYS_CFGSTAT);
 		if (status & SYS_CFGSTAT_ERR)
 			return -EFAULT;

 		if (timeout > 20)
 			timeout -= 20;
 	} while (--tries && !(status & SYS_CFGSTAT_COMPLETE));
 	if (WARN_ON_ONCE(!tries))
 		return -ETIMEDOUT;

 	if (!write) {
 		*data = readl(syscfg->base + SYS_CFGDATA);
 		dev_dbg(syscfg->dev, "func %p, read data %x\n", func, *data);
 	}

 	return 0;
 }

 static int vexpress_syscfg_read(void *context, unsigned int index,
 		unsigned int *val)
 {
 	struct vexpress_syscfg_func *func = context;

 	return vexpress_syscfg_exec(func, index, false, val);
 }

 static int vexpress_syscfg_write(void *context, unsigned int index,
 		unsigned int val)
 {
 	struct vexpress_syscfg_func *func = context;

 	return vexpress_syscfg_exec(func, index, true, &val);
 }

 static struct regmap_config vexpress_syscfg_regmap_config = {
 	.lock = vexpress_config_lock,
 	.unlock = vexpress_config_unlock,
 	.reg_bits = 32,
 	.val_bits = 32,
 	.reg_read = vexpress_syscfg_read,
 	.reg_write = vexpress_syscfg_write,
 	.reg_format_endian = REGMAP_ENDIAN_LITTLE,
 	.val_format_endian = REGMAP_ENDIAN_LITTLE,
 };


 static struct regmap *vexpress_syscfg_regmap_init(struct device *dev,
 		void *context)
 {
 	int err;
 	struct vexpress_syscfg *syscfg = context;
 	struct vexpress_syscfg_func *func;
 	struct property *prop;
 	const __be32 *val = NULL;
 	__be32 energy_quirk[4];
 	int num;
 	u32 site, position, dcc;
 	int i;

 	err = vexpress_config_get_topo(dev->of_node, &site,
 				&position, &dcc);
 	if (err)
 		return ERR_PTR(err);

 	prop = of_find_property(dev->of_node,
 			"arm,vexpress-sysreg,func", NULL);
 	if (!prop)
 		return ERR_PTR(-EINVAL);

 	num = prop->length / sizeof(u32) / 2;
 	val = prop->value;

 	/*
 	 * "arm,vexpress-energy" function used to be described
 	 * by its first device only, now it requires both
 	 */
 	if (num == 1 && of_device_is_compatible(dev->of_node,
 			"arm,vexpress-energy")) {
 		num = 2;
 		energy_quirk[0] = *val;
 		energy_quirk[2] = *val++;
 		energy_quirk[1] = *val;
 		energy_quirk[3] = cpu_to_be32(be32_to_cpup(val) + 1);
 		val = energy_quirk;
 	}

 	func = kzalloc(struct_size(func, template, num), GFP_KERNEL);
 	if (!func)
 		return ERR_PTR(-ENOMEM);

 	func->syscfg = syscfg;
 	func->num_templates = num;

 	for (i = 0; i < num; i++) {
 		u32 function, device;

 		function = be32_to_cpup(val++);
 		device = be32_to_cpup(val++);

 		dev_dbg(dev, "func %p: %u/%u/%u/%u/%u\n",
 				func, site, position, dcc,
 				function, device);

 		func->template[i] = SYS_CFGCTRL_DCC(dcc);
 		func->template[i] |= SYS_CFGCTRL_SITE(site);
 		func->template[i] |= SYS_CFGCTRL_POSITION(position);
 		func->template[i] |= SYS_CFGCTRL_FUNC(function);
 		func->template[i] |= SYS_CFGCTRL_DEVICE(device);
 	}

 	vexpress_syscfg_regmap_config.max_register = num - 1;

 	func->regmap = regmap_init(dev, NULL, func,
 			&vexpress_syscfg_regmap_config);

 	if (IS_ERR(func->regmap)) {
 		void *err = func->regmap;

 		kfree(func);
 		return err;
 	}

 	list_add(&func->list, &syscfg->funcs);

 	return func->regmap;
 }

 static void vexpress_syscfg_regmap_exit(struct regmap *regmap, void *context)
 {
 	struct vexpress_syscfg *syscfg = context;
 	struct vexpress_syscfg_func *func, *tmp;

 	regmap_exit(regmap);

 	list_for_each_entry_safe(func, tmp, &syscfg->funcs, list) {
 		if (func->regmap == regmap) {
 			list_del(&syscfg->funcs);
 			kfree(func);
 			break;
 		}
 	}
 }

 static struct vexpress_config_bridge_ops vexpress_syscfg_bridge_ops = {
 	.regmap_init = vexpress_syscfg_regmap_init,
 	.regmap_exit = vexpress_syscfg_regmap_exit,
 };


 static int vexpress_syscfg_probe(struct platform_device *pdev)
 {
 	struct vexpress_syscfg *syscfg;
 	struct vexpress_config_bridge *bridge;
 	struct device_node *node;
 	int master;
 	u32 dt_hbi;

 	syscfg = devm_kzalloc(&pdev->dev, sizeof(*syscfg), GFP_KERNEL);
 	if (!syscfg)
 		return -ENOMEM;
 	syscfg->dev = &pdev->dev;
 	INIT_LIST_HEAD(&syscfg->funcs);

 	syscfg->base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(syscfg->base))
 		return PTR_ERR(syscfg->base);

 	bridge = devm_kmalloc(&pdev->dev, sizeof(*bridge), GFP_KERNEL);
 	if (!bridge)
 		return -ENOMEM;

 	bridge->ops = &vexpress_syscfg_bridge_ops;
 	bridge->context = syscfg;

 	dev_set_drvdata(&pdev->dev, bridge);

 	master = readl(syscfg->base + SYS_MISC) & SYS_MISC_MASTERSITE ?
 			VEXPRESS_SITE_DB2 : VEXPRESS_SITE_DB1;
 	vexpress_config_set_master(master);

 	/* Confirm board type against DT property, if available */
 	if (of_property_read_u32(of_root, "arm,hbi", &dt_hbi) == 0) {
 		u32 id = readl(syscfg->base + (master == VEXPRESS_SITE_DB1 ?
 				 SYS_PROCID0 : SYS_PROCID1));
 		u32 hbi = (id >> SYS_PROCIDx_HBI_SHIFT) & SYS_HBI_MASK;

 		if (WARN_ON(dt_hbi != hbi))
 			dev_warn(&pdev->dev, "DT HBI (%x) is not matching hardware (%x)!\n",
 					dt_hbi, hbi);
 	}

 	for_each_compatible_node(node, NULL, "arm,vexpress,config-bus") {
 		struct device_node *bridge_np;

 		bridge_np = of_parse_phandle(node, "arm,vexpress,config-bridge", 0);
 		if (bridge_np != pdev->dev.parent->of_node)
 			continue;

 		of_platform_populate(node, NULL, NULL, &pdev->dev);
 	}

 	return 0;
 }

 static const struct platform_device_id vexpress_syscfg_id_table[] = {
 	{ "vexpress-syscfg", },
 	{},
 };
 MODULE_DEVICE_TABLE(platform, vexpress_syscfg_id_table);

 static struct platform_driver vexpress_syscfg_driver = {
 	.driver.name = "vexpress-syscfg",
 	.id_table = vexpress_syscfg_id_table,
 	.probe = vexpress_syscfg_probe,
 };
 module_platform_driver(vexpress_syscfg_driver);
 MODULE_DESCRIPTION("Versatile Express configuration bus");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	*
	* Copyright (C) 2014 ARM Limited
	*/

	#include <linux/err.h>
	#include <linux/init.h>
	#include <linux/io.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/platform_device.h>
	#include <linux/of_platform.h>
	#include <linux/sched/signal.h>
	#include <linux/slab.h>
	#include <linux/vexpress.h>

	#define SYS_MISC 0x0
	#define SYS_MISC_MASTERSITE (1 << 14)

	#define SYS_PROCID0 0x24
	#define SYS_PROCID1 0x28
	#define SYS_HBI_MASK 0xfff
	#define SYS_PROCIDx_HBI_SHIFT 0

	#define SYS_CFGDATA 0x40

	#define SYS_CFGCTRL 0x44
	#define SYS_CFGCTRL_START (1 << 31)
	#define SYS_CFGCTRL_WRITE (1 << 30)
	#define SYS_CFGCTRL_DCC(n) (((n) & 0xf) << 26)
	#define SYS_CFGCTRL_FUNC(n) (((n) & 0x3f) << 20)
	#define SYS_CFGCTRL_SITE(n) (((n) & 0x3) << 16)
	#define SYS_CFGCTRL_POSITION(n) (((n) & 0xf) << 12)
	#define SYS_CFGCTRL_DEVICE(n) (((n) & 0xfff) << 0)

	#define SYS_CFGSTAT 0x48
	#define SYS_CFGSTAT_ERR (1 << 1)
	#define SYS_CFGSTAT_COMPLETE (1 << 0)

	#define VEXPRESS_SITE_MB 0
	#define VEXPRESS_SITE_DB1 1
	#define VEXPRESS_SITE_DB2 2
	#define VEXPRESS_SITE_MASTER 0xf

	struct vexpress_syscfg {
	struct device *dev;
	void __iomem *base;
	struct list_head funcs;
	};

	struct vexpress_syscfg_func {
	struct list_head list;
	struct vexpress_syscfg *syscfg;
	struct regmap *regmap;
	int num_templates;
	u32 template[] __counted_by(num_templates); /* Keep it last! */
	};

	struct vexpress_config_bridge_ops {
	struct regmap * (regmap_init)(struct device dev, void *context);
	void (regmap_exit)(struct regmap regmap, void *context);
	};

	struct vexpress_config_bridge {
	struct vexpress_config_bridge_ops *ops;
	void *context;
	};


	static DEFINE_MUTEX(vexpress_config_mutex);
	static u32 vexpress_config_site_master = VEXPRESS_SITE_MASTER;


	static void vexpress_config_set_master(u32 site)
	{
	vexpress_config_site_master = site;
	}

	static void vexpress_config_lock(void *arg)
	{
	mutex_lock(&vexpress_config_mutex);
	}

	static void vexpress_config_unlock(void *arg)
	{
	mutex_unlock(&vexpress_config_mutex);
	}


	static void vexpress_config_find_prop(struct device_node *node,
	const char name, u32 val)
	{
	/* Default value */
	*val = 0;

	of_node_get(node);
	while (node) {
	if (of_property_read_u32(node, name, val) == 0) {
	of_node_put(node);
	return;
	}
	node = of_get_next_parent(node);
	}
	}

	static int vexpress_config_get_topo(struct device_node node, u32 site,
	u32 position, u32 dcc)
	{
	vexpress_config_find_prop(node, "arm,vexpress,site", site);
	if (*site == VEXPRESS_SITE_MASTER)
	*site = vexpress_config_site_master;
	if (WARN_ON(vexpress_config_site_master == VEXPRESS_SITE_MASTER))
	return -EINVAL;
	vexpress_config_find_prop(node, "arm,vexpress,position", position);
	vexpress_config_find_prop(node, "arm,vexpress,dcc", dcc);

	return 0;
	}


	static void vexpress_config_devres_release(struct device dev, void res)
	{
	struct vexpress_config_bridge *bridge = dev_get_drvdata(dev->parent);
	struct regmap *regmap = res;

	bridge->ops->regmap_exit(regmap, bridge->context);
	}

	struct regmap devm_regmap_init_vexpress_config(struct device dev)
	{
	struct vexpress_config_bridge *bridge;
	struct regmap *regmap;
	struct regmap **res;

	bridge = dev_get_drvdata(dev->parent);
	if (WARN_ON(!bridge))
	return ERR_PTR(-EINVAL);

	res = devres_alloc(vexpress_config_devres_release, sizeof(*res),
	GFP_KERNEL);
	if (!res)
	return ERR_PTR(-ENOMEM);

	regmap = (bridge->ops->regmap_init)(dev, bridge->context);
	if (IS_ERR(regmap)) {
	devres_free(res);
	return regmap;
	}

	*res = regmap;
	devres_add(dev, res);

	return regmap;
	}
	EXPORT_SYMBOL_GPL(devm_regmap_init_vexpress_config);

	static int vexpress_syscfg_exec(struct vexpress_syscfg_func *func,
	int index, bool write, u32 *data)
	{
	struct vexpress_syscfg *syscfg = func->syscfg;
	u32 command, status;
	int tries;
	long timeout;

	if (WARN_ON(index >= func->num_templates))
	return -EINVAL;

	command = readl(syscfg->base + SYS_CFGCTRL);
	if (WARN_ON(command & SYS_CFGCTRL_START))
	return -EBUSY;

	command = func->template[index];
	command \|= SYS_CFGCTRL_START;
	command \|= write ? SYS_CFGCTRL_WRITE : 0;

	/* Use a canary for reads */
	if (!write)
	*data = 0xdeadbeef;

	dev_dbg(syscfg->dev, "func %p, command %x, data %x\n",
	func, command, *data);
	writel(*data, syscfg->base + SYS_CFGDATA);
	writel(0, syscfg->base + SYS_CFGSTAT);
	writel(command, syscfg->base + SYS_CFGCTRL);
	mb();

	/* The operation can take ages... Go to sleep, 100us initially */
	tries = 100;
	timeout = 100;
	do {
	if (!irqs_disabled()) {
	set_current_state(TASK_INTERRUPTIBLE);
	schedule_timeout(usecs_to_jiffies(timeout));
	if (signal_pending(current))
	return -EINTR;
	} else {
	udelay(timeout);
	}

	status = readl(syscfg->base + SYS_CFGSTAT);
	if (status & SYS_CFGSTAT_ERR)
	return -EFAULT;

	if (timeout > 20)
	timeout -= 20;
	} while (--tries && !(status & SYS_CFGSTAT_COMPLETE));
	if (WARN_ON_ONCE(!tries))
	return -ETIMEDOUT;

	if (!write) {
	*data = readl(syscfg->base + SYS_CFGDATA);
	dev_dbg(syscfg->dev, "func %p, read data %x\n", func, *data);
	}

	return 0;
	}

	static int vexpress_syscfg_read(void *context, unsigned int index,
	unsigned int *val)
	{
	struct vexpress_syscfg_func *func = context;

	return vexpress_syscfg_exec(func, index, false, val);
	}

	static int vexpress_syscfg_write(void *context, unsigned int index,
	unsigned int val)
	{
	struct vexpress_syscfg_func *func = context;

	return vexpress_syscfg_exec(func, index, true, &val);
	}

	static struct regmap_config vexpress_syscfg_regmap_config = {
	.lock = vexpress_config_lock,
	.unlock = vexpress_config_unlock,
	.reg_bits = 32,
	.val_bits = 32,
	.reg_read = vexpress_syscfg_read,
	.reg_write = vexpress_syscfg_write,
	.reg_format_endian = REGMAP_ENDIAN_LITTLE,
	.val_format_endian = REGMAP_ENDIAN_LITTLE,
	};


	static struct regmap vexpress_syscfg_regmap_init(struct device dev,
	void *context)
	{
	int err;
	struct vexpress_syscfg *syscfg = context;
	struct vexpress_syscfg_func *func;
	struct property *prop;
	const __be32 *val = NULL;
	__be32 energy_quirk[4];
	int num;
	u32 site, position, dcc;
	int i;

	err = vexpress_config_get_topo(dev->of_node, &site,
	&position, &dcc);
	if (err)
	return ERR_PTR(err);

	prop = of_find_property(dev->of_node,
	"arm,vexpress-sysreg,func", NULL);
	if (!prop)
	return ERR_PTR(-EINVAL);

	num = prop->length / sizeof(u32) / 2;
	val = prop->value;

	/*
	* "arm,vexpress-energy" function used to be described
	* by its first device only, now it requires both
	*/
	if (num == 1 && of_device_is_compatible(dev->of_node,
	"arm,vexpress-energy")) {
	num = 2;
	energy_quirk[0] = *val;
	energy_quirk[2] = *val++;
	energy_quirk[1] = *val;
	energy_quirk[3] = cpu_to_be32(be32_to_cpup(val) + 1);
	val = energy_quirk;
	}

	func = kzalloc(struct_size(func, template, num), GFP_KERNEL);
	if (!func)
	return ERR_PTR(-ENOMEM);

	func->syscfg = syscfg;
	func->num_templates = num;

	for (i = 0; i < num; i++) {
	u32 function, device;

	function = be32_to_cpup(val++);
	device = be32_to_cpup(val++);

	dev_dbg(dev, "func %p: %u/%u/%u/%u/%u\n",
	func, site, position, dcc,
	function, device);

	func->template[i] = SYS_CFGCTRL_DCC(dcc);
	func->template[i] \|= SYS_CFGCTRL_SITE(site);
	func->template[i] \|= SYS_CFGCTRL_POSITION(position);
	func->template[i] \|= SYS_CFGCTRL_FUNC(function);
	func->template[i] \|= SYS_CFGCTRL_DEVICE(device);
	}

	vexpress_syscfg_regmap_config.max_register = num - 1;

	func->regmap = regmap_init(dev, NULL, func,
	&vexpress_syscfg_regmap_config);

	if (IS_ERR(func->regmap)) {
	void *err = func->regmap;

	kfree(func);
	return err;
	}

	list_add(&func->list, &syscfg->funcs);

	return func->regmap;
	}

	static void vexpress_syscfg_regmap_exit(struct regmap regmap, void context)
	{
	struct vexpress_syscfg *syscfg = context;
	struct vexpress_syscfg_func func, tmp;

	regmap_exit(regmap);

	list_for_each_entry_safe(func, tmp, &syscfg->funcs, list) {
	if (func->regmap == regmap) {
	list_del(&syscfg->funcs);
	kfree(func);
	break;
	}
	}
	}

	static struct vexpress_config_bridge_ops vexpress_syscfg_bridge_ops = {
	.regmap_init = vexpress_syscfg_regmap_init,
	.regmap_exit = vexpress_syscfg_regmap_exit,
	};


	static int vexpress_syscfg_probe(struct platform_device *pdev)
	{
	struct vexpress_syscfg *syscfg;
	struct vexpress_config_bridge *bridge;
	struct device_node *node;
	int master;
	u32 dt_hbi;

	syscfg = devm_kzalloc(&pdev->dev, sizeof(*syscfg), GFP_KERNEL);
	if (!syscfg)
	return -ENOMEM;
	syscfg->dev = &pdev->dev;
	INIT_LIST_HEAD(&syscfg->funcs);

	syscfg->base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(syscfg->base))
	return PTR_ERR(syscfg->base);

	bridge = devm_kmalloc(&pdev->dev, sizeof(*bridge), GFP_KERNEL);
	if (!bridge)
	return -ENOMEM;

	bridge->ops = &vexpress_syscfg_bridge_ops;
	bridge->context = syscfg;

	dev_set_drvdata(&pdev->dev, bridge);

	master = readl(syscfg->base + SYS_MISC) & SYS_MISC_MASTERSITE ?
	VEXPRESS_SITE_DB2 : VEXPRESS_SITE_DB1;
	vexpress_config_set_master(master);

	/* Confirm board type against DT property, if available */
	if (of_property_read_u32(of_root, "arm,hbi", &dt_hbi) == 0) {
	u32 id = readl(syscfg->base + (master == VEXPRESS_SITE_DB1 ?
	SYS_PROCID0 : SYS_PROCID1));
	u32 hbi = (id >> SYS_PROCIDx_HBI_SHIFT) & SYS_HBI_MASK;

	if (WARN_ON(dt_hbi != hbi))
	dev_warn(&pdev->dev, "DT HBI (%x) is not matching hardware (%x)!\n",
	dt_hbi, hbi);
	}

	for_each_compatible_node(node, NULL, "arm,vexpress,config-bus") {
	struct device_node *bridge_np;

	bridge_np = of_parse_phandle(node, "arm,vexpress,config-bridge", 0);
	if (bridge_np != pdev->dev.parent->of_node)
	continue;

	of_platform_populate(node, NULL, NULL, &pdev->dev);
	}

	return 0;
	}

	static const struct platform_device_id vexpress_syscfg_id_table[] = {
	{ "vexpress-syscfg", },
	{},
	};
	MODULE_DEVICE_TABLE(platform, vexpress_syscfg_id_table);

	static struct platform_driver vexpress_syscfg_driver = {
	.driver.name = "vexpress-syscfg",
	.id_table = vexpress_syscfg_id_table,
	.probe = vexpress_syscfg_probe,
	};
	module_platform_driver(vexpress_syscfg_driver);
	MODULE_DESCRIPTION("Versatile Express configuration bus");
	MODULE_LICENSE("GPL v2");