drivers/mfd/vexpress-sysreg.c - kernel/msm-5.4 - Gitiles

 /*
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License 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.
  *
  * Copyright (C) 2012 ARM Limited
  */

 #include <linux/err.h>
 #include <linux/gpio.h>
 #include <linux/io.h>
 #include <linux/leds.h>
 #include <linux/of_address.h>
 #include <linux/platform_device.h>
 #include <linux/regulator/driver.h>
 #include <linux/slab.h>
 #include <linux/stat.h>
 #include <linux/timer.h>
 #include <linux/vexpress.h>

 #define SYS_ID			0x000
 #define SYS_SW			0x004
 #define SYS_LED			0x008
 #define SYS_100HZ		0x024
 #define SYS_FLAGS		0x030
 #define SYS_FLAGSSET		0x030
 #define SYS_FLAGSCLR		0x034
 #define SYS_NVFLAGS		0x038
 #define SYS_NVFLAGSSET		0x038
 #define SYS_NVFLAGSCLR		0x03c
 #define SYS_MCI			0x048
 #define SYS_FLASH		0x04c
 #define SYS_CFGSW		0x058
 #define SYS_24MHZ		0x05c
 #define SYS_MISC		0x060
 #define SYS_DMA			0x064
 #define SYS_PROCID0		0x084
 #define SYS_PROCID1		0x088
 #define SYS_CFGDATA		0x0a0
 #define SYS_CFGCTRL		0x0a4
 #define SYS_CFGSTAT		0x0a8

 #define SYS_HBI_MASK		0xfff
 #define SYS_ID_HBI_SHIFT	16
 #define SYS_PROCIDx_HBI_SHIFT	0

 #define SYS_MCI_CARDIN		(1 << 0)
 #define SYS_MCI_WPROT		(1 << 1)

 #define SYS_FLASH_WPn		(1 << 0)

 #define SYS_MISC_MASTERSITE	(1 << 14)

 #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_ERR		(1 << 1)
 #define SYS_CFGSTAT_COMPLETE	(1 << 0)


 static void __iomem *vexpress_sysreg_base;
 static struct device *vexpress_sysreg_dev;
 static int vexpress_master_site;


 void vexpress_flags_set(u32 data)
 {
 	writel(~0, vexpress_sysreg_base + SYS_FLAGSCLR);
 	writel(data, vexpress_sysreg_base + SYS_FLAGSSET);
 }

 u32 vexpress_get_procid(int site)
 {
 	if (site == VEXPRESS_SITE_MASTER)
 		site = vexpress_master_site;

 	return readl(vexpress_sysreg_base + (site == VEXPRESS_SITE_DB1 ?
 			SYS_PROCID0 : SYS_PROCID1));
 }

 u32 vexpress_get_hbi(int site)
 {
 	u32 id;

 	switch (site) {
 	case VEXPRESS_SITE_MB:
 		id = readl(vexpress_sysreg_base + SYS_ID);
 		return (id >> SYS_ID_HBI_SHIFT) & SYS_HBI_MASK;
 	case VEXPRESS_SITE_MASTER:
 	case VEXPRESS_SITE_DB1:
 	case VEXPRESS_SITE_DB2:
 		id = vexpress_get_procid(site);
 		return (id >> SYS_PROCIDx_HBI_SHIFT) & SYS_HBI_MASK;
 	}

 	return ~0;
 }

 void __iomem *vexpress_get_24mhz_clock_base(void)
 {
 	return vexpress_sysreg_base + SYS_24MHZ;
 }


 static void vexpress_sysreg_find_prop(struct device_node *node,
 		const char *name, u32 *val)
 {
 	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);
 	}
 }

 unsigned __vexpress_get_site(struct device *dev, struct device_node *node)
 {
 	u32 site = 0;

 	WARN_ON(dev && node && dev->of_node != node);
 	if (dev && !node)
 		node = dev->of_node;

 	if (node) {
 		vexpress_sysreg_find_prop(node, "arm,vexpress,site", &site);
 	} else if (dev && dev->bus == &platform_bus_type) {
 		struct platform_device *pdev = to_platform_device(dev);

 		if (pdev->num_resources == 1 &&
 				pdev->resource[0].flags == IORESOURCE_BUS)
 			site = pdev->resource[0].start;
 	} else if (dev && strncmp(dev_name(dev), "ct:", 3) == 0) {
 		site = VEXPRESS_SITE_MASTER;
 	}

 	if (site == VEXPRESS_SITE_MASTER)
 		site = vexpress_master_site;

 	return site;
 }


 struct vexpress_sysreg_config_func {
 	u32 template;
 	u32 device;
 };

 static struct vexpress_config_bridge *vexpress_sysreg_config_bridge;
 static struct timer_list vexpress_sysreg_config_timer;
 static u32 *vexpress_sysreg_config_data;
 static int vexpress_sysreg_config_tries;

 static void *vexpress_sysreg_config_func_get(struct device *dev,
 		struct device_node *node)
 {
 	struct vexpress_sysreg_config_func *config_func;
 	u32 site;
 	u32 position = 0;
 	u32 dcc = 0;
 	u32 func_device[2];
 	int err = -EFAULT;

 	if (node) {
 		of_node_get(node);
 		vexpress_sysreg_find_prop(node, "arm,vexpress,site", &site);
 		vexpress_sysreg_find_prop(node, "arm,vexpress,position",
 				&position);
 		vexpress_sysreg_find_prop(node, "arm,vexpress,dcc", &dcc);
 		err = of_property_read_u32_array(node,
 				"arm,vexpress-sysreg,func", func_device,
 				ARRAY_SIZE(func_device));
 		of_node_put(node);
 	} else if (dev && dev->bus == &platform_bus_type) {
 		struct platform_device *pdev = to_platform_device(dev);

 		if (pdev->num_resources == 1 &&
 				pdev->resource[0].flags == IORESOURCE_BUS) {
 			site = pdev->resource[0].start;
 			func_device[0] = pdev->resource[0].end;
 			func_device[1] = pdev->id;
 			err = 0;
 		}
 	}
 	if (err)
 		return NULL;

 	config_func = kzalloc(sizeof(*config_func), GFP_KERNEL);
 	if (!config_func)
 		return NULL;

 	config_func->template = SYS_CFGCTRL_DCC(dcc);
 	config_func->template |= SYS_CFGCTRL_FUNC(func_device[0]);
 	config_func->template |= SYS_CFGCTRL_SITE(site == VEXPRESS_SITE_MASTER ?
 			vexpress_master_site : site);
 	config_func->template |= SYS_CFGCTRL_POSITION(position);
 	config_func->device |= func_device[1];

 	dev_dbg(vexpress_sysreg_dev, "func 0x%p = 0x%x, %d\n", config_func,
 			config_func->template, config_func->device);

 	return config_func;
 }

 static void vexpress_sysreg_config_func_put(void *func)
 {
 	kfree(func);
 }

 static int vexpress_sysreg_config_func_exec(void *func, int offset,
 		bool write, u32 *data)
 {
 	int status;
 	struct vexpress_sysreg_config_func *config_func = func;
 	u32 command;

 	if (WARN_ON(!vexpress_sysreg_base))
 		return -ENOENT;

 	command = readl(vexpress_sysreg_base + SYS_CFGCTRL);
 	if (WARN_ON(command & SYS_CFGCTRL_START))
 		return -EBUSY;

 	command = SYS_CFGCTRL_START;
 	command |= write ? SYS_CFGCTRL_WRITE : 0;
 	command |= config_func->template;
 	command |= SYS_CFGCTRL_DEVICE(config_func->device + offset);

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

 	dev_dbg(vexpress_sysreg_dev, "command %x, data %x\n",
 			command, *data);
 	writel(*data, vexpress_sysreg_base + SYS_CFGDATA);
 	writel(0, vexpress_sysreg_base + SYS_CFGSTAT);
 	writel(command, vexpress_sysreg_base + SYS_CFGCTRL);
 	mb();

 	if (vexpress_sysreg_dev) {
 		/* Schedule completion check */
 		if (!write)
 			vexpress_sysreg_config_data = data;
 		vexpress_sysreg_config_tries = 100;
 		mod_timer(&vexpress_sysreg_config_timer,
 				jiffies + usecs_to_jiffies(100));
 		status = VEXPRESS_CONFIG_STATUS_WAIT;
 	} else {
 		/* Early execution, no timer available, have to spin */
 		u32 cfgstat;

 		do {
 			cpu_relax();
 			cfgstat = readl(vexpress_sysreg_base + SYS_CFGSTAT);
 		} while (!cfgstat);

 		if (!write && (cfgstat & SYS_CFGSTAT_COMPLETE))
 			*data = readl(vexpress_sysreg_base + SYS_CFGDATA);
 		status = VEXPRESS_CONFIG_STATUS_DONE;

 		if (cfgstat & SYS_CFGSTAT_ERR)
 			status = -EINVAL;
 	}

 	return status;
 }

 struct vexpress_config_bridge_info vexpress_sysreg_config_bridge_info = {
 	.name = "vexpress-sysreg",
 	.func_get = vexpress_sysreg_config_func_get,
 	.func_put = vexpress_sysreg_config_func_put,
 	.func_exec = vexpress_sysreg_config_func_exec,
 };

 static void vexpress_sysreg_config_complete(unsigned long data)
 {
 	int status = VEXPRESS_CONFIG_STATUS_DONE;
 	u32 cfgstat = readl(vexpress_sysreg_base + SYS_CFGSTAT);

 	if (cfgstat & SYS_CFGSTAT_ERR)
 		status = -EINVAL;
 	if (!vexpress_sysreg_config_tries--)
 		status = -ETIMEDOUT;

 	if (status < 0) {
 		dev_err(vexpress_sysreg_dev, "error %d\n", status);
 	} else if (!(cfgstat & SYS_CFGSTAT_COMPLETE)) {
 		mod_timer(&vexpress_sysreg_config_timer,
 				jiffies + usecs_to_jiffies(50));
 		return;
 	}

 	if (vexpress_sysreg_config_data) {
 		*vexpress_sysreg_config_data = readl(vexpress_sysreg_base +
 				SYS_CFGDATA);
 		dev_dbg(vexpress_sysreg_dev, "read data %x\n",
 				*vexpress_sysreg_config_data);
 		vexpress_sysreg_config_data = NULL;
 	}

 	vexpress_config_complete(vexpress_sysreg_config_bridge, status);
 }


 void __init vexpress_sysreg_early_init(void __iomem *base)
 {
 	struct device_node *node = of_find_compatible_node(NULL, NULL,
 			"arm,vexpress-sysreg");

 	if (node)
 		base = of_iomap(node, 0);

 	if (WARN_ON(!base))
 		return;

 	vexpress_sysreg_base = base;

 	if (readl(vexpress_sysreg_base + SYS_MISC) & SYS_MISC_MASTERSITE)
 		vexpress_master_site = VEXPRESS_SITE_DB2;
 	else
 		vexpress_master_site = VEXPRESS_SITE_DB1;

 	vexpress_sysreg_config_bridge = vexpress_config_bridge_register(
 			node, &vexpress_sysreg_config_bridge_info);
 	WARN_ON(!vexpress_sysreg_config_bridge);
 }

 void __init vexpress_sysreg_of_early_init(void)
 {
 	vexpress_sysreg_early_init(NULL);
 }


 static struct vexpress_sysreg_gpio {
 	unsigned long reg;
 	u32 value;
 } vexpress_sysreg_gpios[] = {
 	[VEXPRESS_GPIO_MMC_CARDIN] = {
 		.reg = SYS_MCI,
 		.value = SYS_MCI_CARDIN,
 	},
 	[VEXPRESS_GPIO_MMC_WPROT] = {
 		.reg = SYS_MCI,
 		.value = SYS_MCI_WPROT,
 	},
 	[VEXPRESS_GPIO_FLASH_WPn] = {
 		.reg = SYS_FLASH,
 		.value = SYS_FLASH_WPn,
 	},
 };

 static int vexpress_sysreg_gpio_direction_input(struct gpio_chip *chip,
 				       unsigned offset)
 {
 	return 0;
 }

 static int vexpress_sysreg_gpio_direction_output(struct gpio_chip *chip,
 						unsigned offset, int value)
 {
 	return 0;
 }

 static int vexpress_sysreg_gpio_get(struct gpio_chip *chip,
 				       unsigned offset)
 {
 	struct vexpress_sysreg_gpio *gpio = &vexpress_sysreg_gpios[offset];
 	u32 reg_value = readl(vexpress_sysreg_base + gpio->reg);

 	return !!(reg_value & gpio->value);
 }

 static void vexpress_sysreg_gpio_set(struct gpio_chip *chip,
 				       unsigned offset, int value)
 {
 	struct vexpress_sysreg_gpio *gpio = &vexpress_sysreg_gpios[offset];
 	u32 reg_value = readl(vexpress_sysreg_base + gpio->reg);

 	if (value)
 		reg_value |= gpio->value;
 	else
 		reg_value &= ~gpio->value;

 	writel(reg_value, vexpress_sysreg_base + gpio->reg);
 }

 static struct gpio_chip vexpress_sysreg_gpio_chip = {
 	.label = "vexpress-sysreg",
 	.direction_input = vexpress_sysreg_gpio_direction_input,
 	.direction_output = vexpress_sysreg_gpio_direction_output,
 	.get = vexpress_sysreg_gpio_get,
 	.set = vexpress_sysreg_gpio_set,
 	.ngpio = ARRAY_SIZE(vexpress_sysreg_gpios),
 	.base = 0,
 };


 static ssize_t vexpress_sysreg_sys_id_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	return sprintf(buf, "0x%08x\n", readl(vexpress_sysreg_base + SYS_ID));
 }

 DEVICE_ATTR(sys_id, S_IRUGO, vexpress_sysreg_sys_id_show, NULL);

 static int vexpress_sysreg_probe(struct platform_device *pdev)
 {
 	int err;
 	struct resource *res = platform_get_resource(pdev,
 			IORESOURCE_MEM, 0);

 	if (!devm_request_mem_region(&pdev->dev, res->start,
 			resource_size(res), pdev->name)) {
 		dev_err(&pdev->dev, "Failed to request memory region!\n");
 		return -EBUSY;
 	}

 	if (!vexpress_sysreg_base)
 		vexpress_sysreg_base = devm_ioremap(&pdev->dev, res->start,
 				resource_size(res));

 	if (!vexpress_sysreg_base) {
 		dev_err(&pdev->dev, "Failed to obtain base address!\n");
 		return -EFAULT;
 	}

 	setup_timer(&vexpress_sysreg_config_timer,
 			vexpress_sysreg_config_complete, 0);

 	vexpress_sysreg_gpio_chip.dev = &pdev->dev;
 	err = gpiochip_add(&vexpress_sysreg_gpio_chip);
 	if (err) {
 		vexpress_config_bridge_unregister(
 				vexpress_sysreg_config_bridge);
 		dev_err(&pdev->dev, "Failed to register GPIO chip! (%d)\n",
 				err);
 		return err;
 	}

 	vexpress_sysreg_dev = &pdev->dev;

 	device_create_file(vexpress_sysreg_dev, &dev_attr_sys_id);

 	return 0;
 }

 static const struct of_device_id vexpress_sysreg_match[] = {
 	{ .compatible = "arm,vexpress-sysreg", },
 	{},
 };

 static struct platform_driver vexpress_sysreg_driver = {
 	.driver = {
 		.name = "vexpress-sysreg",
 		.of_match_table = vexpress_sysreg_match,
 	},
 	.probe = vexpress_sysreg_probe,
 };

 static int __init vexpress_sysreg_init(void)
 {
 	return platform_driver_register(&vexpress_sysreg_driver);
 }
 core_initcall(vexpress_sysreg_init);
	/*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License 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.
	*
	* Copyright (C) 2012 ARM Limited
	*/

	#include <linux/err.h>
	#include <linux/gpio.h>
	#include <linux/io.h>
	#include <linux/leds.h>
	#include <linux/of_address.h>
	#include <linux/platform_device.h>
	#include <linux/regulator/driver.h>
	#include <linux/slab.h>
	#include <linux/stat.h>
	#include <linux/timer.h>
	#include <linux/vexpress.h>

	#define SYS_ID 0x000
	#define SYS_SW 0x004
	#define SYS_LED 0x008
	#define SYS_100HZ 0x024
	#define SYS_FLAGS 0x030
	#define SYS_FLAGSSET 0x030
	#define SYS_FLAGSCLR 0x034
	#define SYS_NVFLAGS 0x038
	#define SYS_NVFLAGSSET 0x038
	#define SYS_NVFLAGSCLR 0x03c
	#define SYS_MCI 0x048
	#define SYS_FLASH 0x04c
	#define SYS_CFGSW 0x058
	#define SYS_24MHZ 0x05c
	#define SYS_MISC 0x060
	#define SYS_DMA 0x064
	#define SYS_PROCID0 0x084
	#define SYS_PROCID1 0x088
	#define SYS_CFGDATA 0x0a0
	#define SYS_CFGCTRL 0x0a4
	#define SYS_CFGSTAT 0x0a8

	#define SYS_HBI_MASK 0xfff
	#define SYS_ID_HBI_SHIFT 16
	#define SYS_PROCIDx_HBI_SHIFT 0

	#define SYS_MCI_CARDIN (1 << 0)
	#define SYS_MCI_WPROT (1 << 1)

	#define SYS_FLASH_WPn (1 << 0)

	#define SYS_MISC_MASTERSITE (1 << 14)

	#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_ERR (1 << 1)
	#define SYS_CFGSTAT_COMPLETE (1 << 0)


	static void __iomem *vexpress_sysreg_base;
	static struct device *vexpress_sysreg_dev;
	static int vexpress_master_site;


	void vexpress_flags_set(u32 data)
	{
	writel(~0, vexpress_sysreg_base + SYS_FLAGSCLR);
	writel(data, vexpress_sysreg_base + SYS_FLAGSSET);
	}

	u32 vexpress_get_procid(int site)
	{
	if (site == VEXPRESS_SITE_MASTER)
	site = vexpress_master_site;

	return readl(vexpress_sysreg_base + (site == VEXPRESS_SITE_DB1 ?
	SYS_PROCID0 : SYS_PROCID1));
	}

	u32 vexpress_get_hbi(int site)
	{
	u32 id;

	switch (site) {
	case VEXPRESS_SITE_MB:
	id = readl(vexpress_sysreg_base + SYS_ID);
	return (id >> SYS_ID_HBI_SHIFT) & SYS_HBI_MASK;
	case VEXPRESS_SITE_MASTER:
	case VEXPRESS_SITE_DB1:
	case VEXPRESS_SITE_DB2:
	id = vexpress_get_procid(site);
	return (id >> SYS_PROCIDx_HBI_SHIFT) & SYS_HBI_MASK;
	}

	return ~0;
	}

	void __iomem *vexpress_get_24mhz_clock_base(void)
	{
	return vexpress_sysreg_base + SYS_24MHZ;
	}


	static void vexpress_sysreg_find_prop(struct device_node *node,
	const char name, u32 val)
	{
	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);
	}
	}

	unsigned __vexpress_get_site(struct device dev, struct device_node node)
	{
	u32 site = 0;

	WARN_ON(dev && node && dev->of_node != node);
	if (dev && !node)
	node = dev->of_node;

	if (node) {
	vexpress_sysreg_find_prop(node, "arm,vexpress,site", &site);
	} else if (dev && dev->bus == &platform_bus_type) {
	struct platform_device *pdev = to_platform_device(dev);

	if (pdev->num_resources == 1 &&
	pdev->resource[0].flags == IORESOURCE_BUS)
	site = pdev->resource[0].start;
	} else if (dev && strncmp(dev_name(dev), "ct:", 3) == 0) {
	site = VEXPRESS_SITE_MASTER;
	}

	if (site == VEXPRESS_SITE_MASTER)
	site = vexpress_master_site;

	return site;
	}


	struct vexpress_sysreg_config_func {
	u32 template;
	u32 device;
	};

	static struct vexpress_config_bridge *vexpress_sysreg_config_bridge;
	static struct timer_list vexpress_sysreg_config_timer;
	static u32 *vexpress_sysreg_config_data;
	static int vexpress_sysreg_config_tries;

	static void vexpress_sysreg_config_func_get(struct device dev,
	struct device_node *node)
	{
	struct vexpress_sysreg_config_func *config_func;
	u32 site;
	u32 position = 0;
	u32 dcc = 0;
	u32 func_device[2];
	int err = -EFAULT;

	if (node) {
	of_node_get(node);
	vexpress_sysreg_find_prop(node, "arm,vexpress,site", &site);
	vexpress_sysreg_find_prop(node, "arm,vexpress,position",
	&position);
	vexpress_sysreg_find_prop(node, "arm,vexpress,dcc", &dcc);
	err = of_property_read_u32_array(node,
	"arm,vexpress-sysreg,func", func_device,
	ARRAY_SIZE(func_device));
	of_node_put(node);
	} else if (dev && dev->bus == &platform_bus_type) {
	struct platform_device *pdev = to_platform_device(dev);

	if (pdev->num_resources == 1 &&
	pdev->resource[0].flags == IORESOURCE_BUS) {
	site = pdev->resource[0].start;
	func_device[0] = pdev->resource[0].end;
	func_device[1] = pdev->id;
	err = 0;
	}
	}
	if (err)
	return NULL;

	config_func = kzalloc(sizeof(*config_func), GFP_KERNEL);
	if (!config_func)
	return NULL;

	config_func->template = SYS_CFGCTRL_DCC(dcc);
	config_func->template \|= SYS_CFGCTRL_FUNC(func_device[0]);
	config_func->template \|= SYS_CFGCTRL_SITE(site == VEXPRESS_SITE_MASTER ?
	vexpress_master_site : site);
	config_func->template \|= SYS_CFGCTRL_POSITION(position);
	config_func->device \|= func_device[1];

	dev_dbg(vexpress_sysreg_dev, "func 0x%p = 0x%x, %d\n", config_func,
	config_func->template, config_func->device);

	return config_func;
	}

	static void vexpress_sysreg_config_func_put(void *func)
	{
	kfree(func);
	}

	static int vexpress_sysreg_config_func_exec(void *func, int offset,
	bool write, u32 *data)
	{
	int status;
	struct vexpress_sysreg_config_func *config_func = func;
	u32 command;

	if (WARN_ON(!vexpress_sysreg_base))
	return -ENOENT;

	command = readl(vexpress_sysreg_base + SYS_CFGCTRL);
	if (WARN_ON(command & SYS_CFGCTRL_START))
	return -EBUSY;

	command = SYS_CFGCTRL_START;
	command \|= write ? SYS_CFGCTRL_WRITE : 0;
	command \|= config_func->template;
	command \|= SYS_CFGCTRL_DEVICE(config_func->device + offset);

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

	dev_dbg(vexpress_sysreg_dev, "command %x, data %x\n",
	command, *data);
	writel(*data, vexpress_sysreg_base + SYS_CFGDATA);
	writel(0, vexpress_sysreg_base + SYS_CFGSTAT);
	writel(command, vexpress_sysreg_base + SYS_CFGCTRL);
	mb();

	if (vexpress_sysreg_dev) {
	/* Schedule completion check */
	if (!write)
	vexpress_sysreg_config_data = data;
	vexpress_sysreg_config_tries = 100;
	mod_timer(&vexpress_sysreg_config_timer,
	jiffies + usecs_to_jiffies(100));
	status = VEXPRESS_CONFIG_STATUS_WAIT;
	} else {
	/* Early execution, no timer available, have to spin */
	u32 cfgstat;

	do {
	cpu_relax();
	cfgstat = readl(vexpress_sysreg_base + SYS_CFGSTAT);
	} while (!cfgstat);

	if (!write && (cfgstat & SYS_CFGSTAT_COMPLETE))
	*data = readl(vexpress_sysreg_base + SYS_CFGDATA);
	status = VEXPRESS_CONFIG_STATUS_DONE;

	if (cfgstat & SYS_CFGSTAT_ERR)
	status = -EINVAL;
	}

	return status;
	}

	struct vexpress_config_bridge_info vexpress_sysreg_config_bridge_info = {
	.name = "vexpress-sysreg",
	.func_get = vexpress_sysreg_config_func_get,
	.func_put = vexpress_sysreg_config_func_put,
	.func_exec = vexpress_sysreg_config_func_exec,
	};

	static void vexpress_sysreg_config_complete(unsigned long data)
	{
	int status = VEXPRESS_CONFIG_STATUS_DONE;
	u32 cfgstat = readl(vexpress_sysreg_base + SYS_CFGSTAT);

	if (cfgstat & SYS_CFGSTAT_ERR)
	status = -EINVAL;
	if (!vexpress_sysreg_config_tries--)
	status = -ETIMEDOUT;

	if (status < 0) {
	dev_err(vexpress_sysreg_dev, "error %d\n", status);
	} else if (!(cfgstat & SYS_CFGSTAT_COMPLETE)) {
	mod_timer(&vexpress_sysreg_config_timer,
	jiffies + usecs_to_jiffies(50));
	return;
	}

	if (vexpress_sysreg_config_data) {
	*vexpress_sysreg_config_data = readl(vexpress_sysreg_base +
	SYS_CFGDATA);
	dev_dbg(vexpress_sysreg_dev, "read data %x\n",
	*vexpress_sysreg_config_data);
	vexpress_sysreg_config_data = NULL;
	}

	vexpress_config_complete(vexpress_sysreg_config_bridge, status);
	}


	void __init vexpress_sysreg_early_init(void __iomem *base)
	{
	struct device_node *node = of_find_compatible_node(NULL, NULL,
	"arm,vexpress-sysreg");

	if (node)
	base = of_iomap(node, 0);

	if (WARN_ON(!base))
	return;

	vexpress_sysreg_base = base;

	if (readl(vexpress_sysreg_base + SYS_MISC) & SYS_MISC_MASTERSITE)
	vexpress_master_site = VEXPRESS_SITE_DB2;
	else
	vexpress_master_site = VEXPRESS_SITE_DB1;

	vexpress_sysreg_config_bridge = vexpress_config_bridge_register(
	node, &vexpress_sysreg_config_bridge_info);
	WARN_ON(!vexpress_sysreg_config_bridge);
	}

	void __init vexpress_sysreg_of_early_init(void)
	{
	vexpress_sysreg_early_init(NULL);
	}


	static struct vexpress_sysreg_gpio {
	unsigned long reg;
	u32 value;
	} vexpress_sysreg_gpios[] = {
	[VEXPRESS_GPIO_MMC_CARDIN] = {
	.reg = SYS_MCI,
	.value = SYS_MCI_CARDIN,
	},
	[VEXPRESS_GPIO_MMC_WPROT] = {
	.reg = SYS_MCI,
	.value = SYS_MCI_WPROT,
	},
	[VEXPRESS_GPIO_FLASH_WPn] = {
	.reg = SYS_FLASH,
	.value = SYS_FLASH_WPn,
	},
	};

	static int vexpress_sysreg_gpio_direction_input(struct gpio_chip *chip,
	unsigned offset)
	{
	return 0;
	}

	static int vexpress_sysreg_gpio_direction_output(struct gpio_chip *chip,
	unsigned offset, int value)
	{
	return 0;
	}

	static int vexpress_sysreg_gpio_get(struct gpio_chip *chip,
	unsigned offset)
	{
	struct vexpress_sysreg_gpio *gpio = &vexpress_sysreg_gpios[offset];
	u32 reg_value = readl(vexpress_sysreg_base + gpio->reg);

	return !!(reg_value & gpio->value);
	}

	static void vexpress_sysreg_gpio_set(struct gpio_chip *chip,
	unsigned offset, int value)
	{
	struct vexpress_sysreg_gpio *gpio = &vexpress_sysreg_gpios[offset];
	u32 reg_value = readl(vexpress_sysreg_base + gpio->reg);

	if (value)
	reg_value \|= gpio->value;
	else
	reg_value &= ~gpio->value;

	writel(reg_value, vexpress_sysreg_base + gpio->reg);
	}

	static struct gpio_chip vexpress_sysreg_gpio_chip = {
	.label = "vexpress-sysreg",
	.direction_input = vexpress_sysreg_gpio_direction_input,
	.direction_output = vexpress_sysreg_gpio_direction_output,
	.get = vexpress_sysreg_gpio_get,
	.set = vexpress_sysreg_gpio_set,
	.ngpio = ARRAY_SIZE(vexpress_sysreg_gpios),
	.base = 0,
	};


	static ssize_t vexpress_sysreg_sys_id_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	return sprintf(buf, "0x%08x\n", readl(vexpress_sysreg_base + SYS_ID));
	}

	DEVICE_ATTR(sys_id, S_IRUGO, vexpress_sysreg_sys_id_show, NULL);

	static int vexpress_sysreg_probe(struct platform_device *pdev)
	{
	int err;
	struct resource *res = platform_get_resource(pdev,
	IORESOURCE_MEM, 0);

	if (!devm_request_mem_region(&pdev->dev, res->start,
	resource_size(res), pdev->name)) {
	dev_err(&pdev->dev, "Failed to request memory region!\n");
	return -EBUSY;
	}

	if (!vexpress_sysreg_base)
	vexpress_sysreg_base = devm_ioremap(&pdev->dev, res->start,
	resource_size(res));

	if (!vexpress_sysreg_base) {
	dev_err(&pdev->dev, "Failed to obtain base address!\n");
	return -EFAULT;
	}

	setup_timer(&vexpress_sysreg_config_timer,
	vexpress_sysreg_config_complete, 0);

	vexpress_sysreg_gpio_chip.dev = &pdev->dev;
	err = gpiochip_add(&vexpress_sysreg_gpio_chip);
	if (err) {
	vexpress_config_bridge_unregister(
	vexpress_sysreg_config_bridge);
	dev_err(&pdev->dev, "Failed to register GPIO chip! (%d)\n",
	err);
	return err;
	}

	vexpress_sysreg_dev = &pdev->dev;

	device_create_file(vexpress_sysreg_dev, &dev_attr_sys_id);

	return 0;
	}

	static const struct of_device_id vexpress_sysreg_match[] = {
	{ .compatible = "arm,vexpress-sysreg", },
	{},
	};

	static struct platform_driver vexpress_sysreg_driver = {
	.driver = {
	.name = "vexpress-sysreg",
	.of_match_table = vexpress_sysreg_match,
	},
	.probe = vexpress_sysreg_probe,
	};

	static int __init vexpress_sysreg_init(void)
	{
	return platform_driver_register(&vexpress_sysreg_driver);
	}
	core_initcall(vexpress_sysreg_init);