drivers/bus/intel-ixp4xx-eb.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Intel IXP4xx Expansion Bus Controller
  * Copyright (C) 2021 Linaro Ltd.
  *
  * Author: Linus Walleij <linus.walleij@linaro.org>
  */

 #include <linux/bitfield.h>
 #include <linux/bits.h>
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/log2.h>
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>

 #define IXP4XX_EXP_NUM_CS		8

 #define IXP4XX_EXP_TIMING_CS0		0x00
 #define IXP4XX_EXP_TIMING_CS1		0x04
 #define IXP4XX_EXP_TIMING_CS2		0x08
 #define IXP4XX_EXP_TIMING_CS3		0x0c
 #define IXP4XX_EXP_TIMING_CS4		0x10
 #define IXP4XX_EXP_TIMING_CS5		0x14
 #define IXP4XX_EXP_TIMING_CS6		0x18
 #define IXP4XX_EXP_TIMING_CS7		0x1c

 /* Bits inside each CS timing register */
 #define IXP4XX_EXP_TIMING_STRIDE	0x04
 #define IXP4XX_EXP_CS_EN		BIT(31)
 #define IXP456_EXP_PAR_EN		BIT(30) /* Only on IXP45x and IXP46x */
 #define IXP4XX_EXP_T1_MASK		GENMASK(28, 27)
 #define IXP4XX_EXP_T1_SHIFT		28
 #define IXP4XX_EXP_T2_MASK		GENMASK(27, 26)
 #define IXP4XX_EXP_T2_SHIFT		26
 #define IXP4XX_EXP_T3_MASK		GENMASK(25, 22)
 #define IXP4XX_EXP_T3_SHIFT		22
 #define IXP4XX_EXP_T4_MASK		GENMASK(21, 20)
 #define IXP4XX_EXP_T4_SHIFT		20
 #define IXP4XX_EXP_T5_MASK		GENMASK(19, 16)
 #define IXP4XX_EXP_T5_SHIFT		16
 #define IXP4XX_EXP_CYC_TYPE_MASK	GENMASK(15, 14)
 #define IXP4XX_EXP_CYC_TYPE_SHIFT	14
 #define IXP4XX_EXP_SIZE_MASK		GENMASK(13, 10)
 #define IXP4XX_EXP_SIZE_SHIFT		10
 #define IXP4XX_EXP_CNFG_0		BIT(9) /* Always zero */
 #define IXP43X_EXP_SYNC_INTEL		BIT(8) /* Only on IXP43x */
 #define IXP43X_EXP_EXP_CHIP		BIT(7) /* Only on IXP43x, dangerous to touch on IXP42x */
 #define IXP4XX_EXP_BYTE_RD16		BIT(6)
 #define IXP4XX_EXP_HRDY_POL		BIT(5) /* Only on IXP42x */
 #define IXP4XX_EXP_MUX_EN		BIT(4)
 #define IXP4XX_EXP_SPLT_EN		BIT(3)
 #define IXP4XX_EXP_WORD			BIT(2) /* Always zero */
 #define IXP4XX_EXP_WR_EN		BIT(1)
 #define IXP4XX_EXP_BYTE_EN		BIT(0)

 #define IXP4XX_EXP_CNFG0		0x20
 #define IXP4XX_EXP_CNFG0_MEM_MAP	BIT(31)
 #define IXP4XX_EXP_CNFG1		0x24

 #define IXP4XX_EXP_BOOT_BASE		0x00000000
 #define IXP4XX_EXP_NORMAL_BASE		0x50000000
 #define IXP4XX_EXP_STRIDE		0x01000000

 /* Fuses on the IXP43x */
 #define IXP43X_EXP_UNIT_FUSE_RESET	0x28
 #define IXP43x_EXP_FUSE_SPEED_MASK	GENMASK(23, 22)

 /* Number of device tree values in "reg" */
 #define IXP4XX_OF_REG_SIZE		3

 struct ixp4xx_eb {
 	struct device *dev;
 	struct regmap *rmap;
 	u32 bus_base;
 	bool is_42x;
 	bool is_43x;
 };

 struct ixp4xx_exp_tim_prop {
 	const char *prop;
 	u32 max;
 	u32 mask;
 	u16 shift;
 };

 static const struct ixp4xx_exp_tim_prop ixp4xx_exp_tim_props[] = {
 	{
 		.prop = "intel,ixp4xx-eb-t1",
 		.max = 3,
 		.mask = IXP4XX_EXP_T1_MASK,
 		.shift = IXP4XX_EXP_T1_SHIFT,
 	},
 	{
 		.prop = "intel,ixp4xx-eb-t2",
 		.max = 3,
 		.mask = IXP4XX_EXP_T2_MASK,
 		.shift = IXP4XX_EXP_T2_SHIFT,
 	},
 	{
 		.prop = "intel,ixp4xx-eb-t3",
 		.max = 15,
 		.mask = IXP4XX_EXP_T3_MASK,
 		.shift = IXP4XX_EXP_T3_SHIFT,
 	},
 	{
 		.prop = "intel,ixp4xx-eb-t4",
 		.max = 3,
 		.mask = IXP4XX_EXP_T4_MASK,
 		.shift = IXP4XX_EXP_T4_SHIFT,
 	},
 	{
 		.prop = "intel,ixp4xx-eb-t5",
 		.max = 15,
 		.mask = IXP4XX_EXP_T5_MASK,
 		.shift = IXP4XX_EXP_T5_SHIFT,
 	},
 	{
 		.prop = "intel,ixp4xx-eb-byte-access-on-halfword",
 		.max = 1,
 		.mask = IXP4XX_EXP_BYTE_RD16,
 	},
 	{
 		.prop = "intel,ixp4xx-eb-hpi-hrdy-pol-high",
 		.max = 1,
 		.mask = IXP4XX_EXP_HRDY_POL,
 	},
 	{
 		.prop = "intel,ixp4xx-eb-mux-address-and-data",
 		.max = 1,
 		.mask = IXP4XX_EXP_MUX_EN,
 	},
 	{
 		.prop = "intel,ixp4xx-eb-ahb-split-transfers",
 		.max = 1,
 		.mask = IXP4XX_EXP_SPLT_EN,
 	},
 	{
 		.prop = "intel,ixp4xx-eb-write-enable",
 		.max = 1,
 		.mask = IXP4XX_EXP_WR_EN,
 	},
 	{
 		.prop = "intel,ixp4xx-eb-byte-access",
 		.max = 1,
 		.mask = IXP4XX_EXP_BYTE_EN,
 	},
 };

 static void ixp4xx_exp_setup_chipselect(struct ixp4xx_eb *eb,
 					struct device_node *np,
 					u32 cs_index,
 					u32 cs_size)
 {
 	u32 cs_cfg;
 	u32 val;
 	u32 cur_cssize;
 	u32 cs_order;
 	int ret;
 	int i;

 	if (eb->is_42x && (cs_index > 7)) {
 		dev_err(eb->dev,
 			"invalid chipselect %u, we only support 0-7\n",
 			cs_index);
 		return;
 	}
 	if (eb->is_43x && (cs_index > 3)) {
 		dev_err(eb->dev,
 			"invalid chipselect %u, we only support 0-3\n",
 			cs_index);
 		return;
 	}

 	/* Several chip selects can be joined into one device */
 	if (cs_size > IXP4XX_EXP_STRIDE)
 		cur_cssize = IXP4XX_EXP_STRIDE;
 	else
 		cur_cssize = cs_size;


 	/*
 	 * The following will read/modify/write the configuration for one
 	 * chipselect, attempting to leave the boot defaults in place unless
 	 * something is explicitly defined.
 	 */
 	regmap_read(eb->rmap, IXP4XX_EXP_TIMING_CS0 +
 		    IXP4XX_EXP_TIMING_STRIDE * cs_index, &cs_cfg);
 	dev_info(eb->dev, "CS%d at %#08x, size %#08x, config before: %#08x\n",
 		 cs_index, eb->bus_base + IXP4XX_EXP_STRIDE * cs_index,
 		 cur_cssize, cs_cfg);

 	/* Size set-up first align to 2^9 .. 2^24 */
 	cur_cssize = roundup_pow_of_two(cur_cssize);
 	if (cur_cssize < 512)
 		cur_cssize = 512;
 	cs_order = ilog2(cur_cssize);
 	if (cs_order < 9 || cs_order > 24) {
 		dev_err(eb->dev, "illegal size order %d\n", cs_order);
 		return;
 	}
 	dev_dbg(eb->dev, "CS%d size order: %d\n", cs_index, cs_order);
 	cs_cfg &= ~(IXP4XX_EXP_SIZE_MASK);
 	cs_cfg |= ((cs_order - 9) << IXP4XX_EXP_SIZE_SHIFT);

 	for (i = 0; i < ARRAY_SIZE(ixp4xx_exp_tim_props); i++) {
 		const struct ixp4xx_exp_tim_prop *ip = &ixp4xx_exp_tim_props[i];

 		/* All are regular u32 values */
 		ret = of_property_read_u32(np, ip->prop, &val);
 		if (ret)
 			continue;

 		/* Handle bools (single bits) first */
 		if (ip->max == 1) {
 			if (val)
 				cs_cfg |= ip->mask;
 			else
 				cs_cfg &= ~ip->mask;
 			dev_info(eb->dev, "CS%d %s %s\n", cs_index,
 				 val ? "enabled" : "disabled",
 				 ip->prop);
 			continue;
 		}

 		if (val > ip->max) {
 			dev_err(eb->dev,
 				"CS%d too high value for %s: %u, capped at %u\n",
 				cs_index, ip->prop, val, ip->max);
 			val = ip->max;
 		}
 		/* This assumes max value fills all the assigned bits (and it does) */
 		cs_cfg &= ~ip->mask;
 		cs_cfg |= (val << ip->shift);
 		dev_info(eb->dev, "CS%d set %s to %u\n", cs_index, ip->prop, val);
 	}

 	ret = of_property_read_u32(np, "intel,ixp4xx-eb-cycle-type", &val);
 	if (!ret) {
 		if (val > 3) {
 			dev_err(eb->dev, "illegal cycle type %d\n", val);
 			return;
 		}
 		dev_info(eb->dev, "CS%d set cycle type %d\n", cs_index, val);
 		cs_cfg &= ~IXP4XX_EXP_CYC_TYPE_MASK;
 		cs_cfg |= val << IXP4XX_EXP_CYC_TYPE_SHIFT;
 	}

 	if (eb->is_43x) {
 		/* Should always be zero */
 		cs_cfg &= ~IXP4XX_EXP_WORD;
 		/*
 		 * This bit for Intel strata flash is currently unused, but let's
 		 * report it if we find one.
 		 */
 		if (cs_cfg & IXP43X_EXP_SYNC_INTEL)
 			dev_info(eb->dev, "claims to be Intel strata flash\n");
 	}
 	cs_cfg |= IXP4XX_EXP_CS_EN;

 	regmap_write(eb->rmap,
 		     IXP4XX_EXP_TIMING_CS0 + IXP4XX_EXP_TIMING_STRIDE * cs_index,
 		     cs_cfg);
 	dev_info(eb->dev, "CS%d wrote %#08x into CS config\n", cs_index, cs_cfg);

 	/*
 	 * If several chip selects are joined together into one big
 	 * device area, we call ourselves recursively for each successive
 	 * chip select. For a 32MB flash chip this results in two calls
 	 * for example.
 	 */
 	if (cs_size > IXP4XX_EXP_STRIDE)
 		ixp4xx_exp_setup_chipselect(eb, np,
 					    cs_index + 1,
 					    cs_size - IXP4XX_EXP_STRIDE);
 }

 static void ixp4xx_exp_setup_child(struct ixp4xx_eb *eb,
 				   struct device_node *np)
 {
 	u32 cs_sizes[IXP4XX_EXP_NUM_CS];
 	int num_regs;
 	u32 csindex;
 	u32 cssize;
 	int ret;
 	int i;

 	num_regs = of_property_count_elems_of_size(np, "reg", IXP4XX_OF_REG_SIZE);
 	if (num_regs <= 0)
 		return;
 	dev_dbg(eb->dev, "child %s has %d register sets\n",
 		of_node_full_name(np), num_regs);

 	for (csindex = 0; csindex < IXP4XX_EXP_NUM_CS; csindex++)
 		cs_sizes[csindex] = 0;

 	for (i = 0; i < num_regs; i++) {
 		u32 rbase, rsize;

 		ret = of_property_read_u32_index(np, "reg",
 						 i * IXP4XX_OF_REG_SIZE, &csindex);
 		if (ret)
 			break;
 		ret = of_property_read_u32_index(np, "reg",
 						 i * IXP4XX_OF_REG_SIZE + 1, &rbase);
 		if (ret)
 			break;
 		ret = of_property_read_u32_index(np, "reg",
 						 i * IXP4XX_OF_REG_SIZE + 2, &rsize);
 		if (ret)
 			break;

 		if (csindex >= IXP4XX_EXP_NUM_CS) {
 			dev_err(eb->dev, "illegal CS %d\n", csindex);
 			continue;
 		}
 		/*
 		 * The memory window always starts from CS base so we need to add
 		 * the start and size to get to the size from the start of the CS
 		 * base. For example if CS0 is at 0x50000000 and the reg is
 		 * <0 0xe40000 0x40000> the size is e80000.
 		 *
 		 * Roof this if we have several regs setting the same CS.
 		 */
 		cssize = rbase + rsize;
 		dev_dbg(eb->dev, "CS%d size %#08x\n", csindex, cssize);
 		if (cs_sizes[csindex] < cssize)
 			cs_sizes[csindex] = cssize;
 	}

 	for (csindex = 0; csindex < IXP4XX_EXP_NUM_CS; csindex++) {
 		cssize = cs_sizes[csindex];
 		if (!cssize)
 			continue;
 		/* Just this one, so set it up and return */
 		ixp4xx_exp_setup_chipselect(eb, np, csindex, cssize);
 	}
 }

 static int ixp4xx_exp_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct device_node *np = dev->of_node;
 	struct ixp4xx_eb *eb;
 	struct device_node *child;
 	bool have_children = false;
 	u32 val;
 	int ret;

 	eb = devm_kzalloc(dev, sizeof(*eb), GFP_KERNEL);
 	if (!eb)
 		return -ENOMEM;

 	eb->dev = dev;
 	eb->is_42x = of_device_is_compatible(np, "intel,ixp42x-expansion-bus-controller");
 	eb->is_43x = of_device_is_compatible(np, "intel,ixp43x-expansion-bus-controller");

 	eb->rmap = syscon_node_to_regmap(np);
 	if (IS_ERR(eb->rmap))
 		return dev_err_probe(dev, PTR_ERR(eb->rmap), "no regmap\n");

 	/* We check that the regmap work only on first read */
 	ret = regmap_read(eb->rmap, IXP4XX_EXP_CNFG0, &val);
 	if (ret)
 		return dev_err_probe(dev, ret, "cannot read regmap\n");
 	if (val & IXP4XX_EXP_CNFG0_MEM_MAP)
 		eb->bus_base = IXP4XX_EXP_BOOT_BASE;
 	else
 		eb->bus_base = IXP4XX_EXP_NORMAL_BASE;
 	dev_info(dev, "expansion bus at %08x\n", eb->bus_base);

 	if (eb->is_43x) {
 		/* Check some fuses */
 		regmap_read(eb->rmap, IXP43X_EXP_UNIT_FUSE_RESET, &val);
 		switch (FIELD_GET(IXP43x_EXP_FUSE_SPEED_MASK, val)) {
 		case 0:
 			dev_info(dev, "IXP43x at 533 MHz\n");
 			break;
 		case 1:
 			dev_info(dev, "IXP43x at 400 MHz\n");
 			break;
 		case 2:
 			dev_info(dev, "IXP43x at 667 MHz\n");
 			break;
 		default:
 			dev_info(dev, "IXP43x unknown speed\n");
 			break;
 		}
 	}

 	/* Walk over the child nodes and see what chipselects we use */
 	for_each_available_child_of_node(np, child) {
 		ixp4xx_exp_setup_child(eb, child);
 		/* We have at least one child */
 		have_children = true;
 	}

 	if (have_children)
 		return of_platform_default_populate(np, NULL, dev);

 	return 0;
 }

 static const struct of_device_id ixp4xx_exp_of_match[] = {
 	{ .compatible = "intel,ixp42x-expansion-bus-controller", },
 	{ .compatible = "intel,ixp43x-expansion-bus-controller", },
 	{ .compatible = "intel,ixp45x-expansion-bus-controller", },
 	{ .compatible = "intel,ixp46x-expansion-bus-controller", },
 	{ }
 };

 static struct platform_driver ixp4xx_exp_driver = {
 	.probe = ixp4xx_exp_probe,
 	.driver = {
 		.name = "intel-extbus",
 		.of_match_table = ixp4xx_exp_of_match,
 	},
 };
 module_platform_driver(ixp4xx_exp_driver);
 MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
 MODULE_DESCRIPTION("Intel IXP4xx external bus driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Intel IXP4xx Expansion Bus Controller
	* Copyright (C) 2021 Linaro Ltd.
	*
	* Author: Linus Walleij <linus.walleij@linaro.org>
	*/

	#include <linux/bitfield.h>
	#include <linux/bits.h>
	#include <linux/err.h>
	#include <linux/init.h>
	#include <linux/log2.h>
	#include <linux/mfd/syscon.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/of_platform.h>
	#include <linux/platform_device.h>
	#include <linux/regmap.h>

	#define IXP4XX_EXP_NUM_CS 8

	#define IXP4XX_EXP_TIMING_CS0 0x00
	#define IXP4XX_EXP_TIMING_CS1 0x04
	#define IXP4XX_EXP_TIMING_CS2 0x08
	#define IXP4XX_EXP_TIMING_CS3 0x0c
	#define IXP4XX_EXP_TIMING_CS4 0x10
	#define IXP4XX_EXP_TIMING_CS5 0x14
	#define IXP4XX_EXP_TIMING_CS6 0x18
	#define IXP4XX_EXP_TIMING_CS7 0x1c

	/* Bits inside each CS timing register */
	#define IXP4XX_EXP_TIMING_STRIDE 0x04
	#define IXP4XX_EXP_CS_EN BIT(31)
	#define IXP456_EXP_PAR_EN BIT(30) /* Only on IXP45x and IXP46x */
	#define IXP4XX_EXP_T1_MASK GENMASK(28, 27)
	#define IXP4XX_EXP_T1_SHIFT 28
	#define IXP4XX_EXP_T2_MASK GENMASK(27, 26)
	#define IXP4XX_EXP_T2_SHIFT 26
	#define IXP4XX_EXP_T3_MASK GENMASK(25, 22)
	#define IXP4XX_EXP_T3_SHIFT 22
	#define IXP4XX_EXP_T4_MASK GENMASK(21, 20)
	#define IXP4XX_EXP_T4_SHIFT 20
	#define IXP4XX_EXP_T5_MASK GENMASK(19, 16)
	#define IXP4XX_EXP_T5_SHIFT 16
	#define IXP4XX_EXP_CYC_TYPE_MASK GENMASK(15, 14)
	#define IXP4XX_EXP_CYC_TYPE_SHIFT 14
	#define IXP4XX_EXP_SIZE_MASK GENMASK(13, 10)
	#define IXP4XX_EXP_SIZE_SHIFT 10
	#define IXP4XX_EXP_CNFG_0 BIT(9) /* Always zero */
	#define IXP43X_EXP_SYNC_INTEL BIT(8) /* Only on IXP43x */
	#define IXP43X_EXP_EXP_CHIP BIT(7) /* Only on IXP43x, dangerous to touch on IXP42x */
	#define IXP4XX_EXP_BYTE_RD16 BIT(6)
	#define IXP4XX_EXP_HRDY_POL BIT(5) /* Only on IXP42x */
	#define IXP4XX_EXP_MUX_EN BIT(4)
	#define IXP4XX_EXP_SPLT_EN BIT(3)
	#define IXP4XX_EXP_WORD BIT(2) /* Always zero */
	#define IXP4XX_EXP_WR_EN BIT(1)
	#define IXP4XX_EXP_BYTE_EN BIT(0)

	#define IXP4XX_EXP_CNFG0 0x20
	#define IXP4XX_EXP_CNFG0_MEM_MAP BIT(31)
	#define IXP4XX_EXP_CNFG1 0x24

	#define IXP4XX_EXP_BOOT_BASE 0x00000000
	#define IXP4XX_EXP_NORMAL_BASE 0x50000000
	#define IXP4XX_EXP_STRIDE 0x01000000

	/* Fuses on the IXP43x */
	#define IXP43X_EXP_UNIT_FUSE_RESET 0x28
	#define IXP43x_EXP_FUSE_SPEED_MASK GENMASK(23, 22)

	/* Number of device tree values in "reg" */
	#define IXP4XX_OF_REG_SIZE 3

	struct ixp4xx_eb {
	struct device *dev;
	struct regmap *rmap;
	u32 bus_base;
	bool is_42x;
	bool is_43x;
	};

	struct ixp4xx_exp_tim_prop {
	const char *prop;
	u32 max;
	u32 mask;
	u16 shift;
	};

	static const struct ixp4xx_exp_tim_prop ixp4xx_exp_tim_props[] = {
	{
	.prop = "intel,ixp4xx-eb-t1",
	.max = 3,
	.mask = IXP4XX_EXP_T1_MASK,
	.shift = IXP4XX_EXP_T1_SHIFT,
	},
	{
	.prop = "intel,ixp4xx-eb-t2",
	.max = 3,
	.mask = IXP4XX_EXP_T2_MASK,
	.shift = IXP4XX_EXP_T2_SHIFT,
	},
	{
	.prop = "intel,ixp4xx-eb-t3",
	.max = 15,
	.mask = IXP4XX_EXP_T3_MASK,
	.shift = IXP4XX_EXP_T3_SHIFT,
	},
	{
	.prop = "intel,ixp4xx-eb-t4",
	.max = 3,
	.mask = IXP4XX_EXP_T4_MASK,
	.shift = IXP4XX_EXP_T4_SHIFT,
	},
	{
	.prop = "intel,ixp4xx-eb-t5",
	.max = 15,
	.mask = IXP4XX_EXP_T5_MASK,
	.shift = IXP4XX_EXP_T5_SHIFT,
	},
	{
	.prop = "intel,ixp4xx-eb-byte-access-on-halfword",
	.max = 1,
	.mask = IXP4XX_EXP_BYTE_RD16,
	},
	{
	.prop = "intel,ixp4xx-eb-hpi-hrdy-pol-high",
	.max = 1,
	.mask = IXP4XX_EXP_HRDY_POL,
	},
	{
	.prop = "intel,ixp4xx-eb-mux-address-and-data",
	.max = 1,
	.mask = IXP4XX_EXP_MUX_EN,
	},
	{
	.prop = "intel,ixp4xx-eb-ahb-split-transfers",
	.max = 1,
	.mask = IXP4XX_EXP_SPLT_EN,
	},
	{
	.prop = "intel,ixp4xx-eb-write-enable",
	.max = 1,
	.mask = IXP4XX_EXP_WR_EN,
	},
	{
	.prop = "intel,ixp4xx-eb-byte-access",
	.max = 1,
	.mask = IXP4XX_EXP_BYTE_EN,
	},
	};

	static void ixp4xx_exp_setup_chipselect(struct ixp4xx_eb *eb,
	struct device_node *np,
	u32 cs_index,
	u32 cs_size)
	{
	u32 cs_cfg;
	u32 val;
	u32 cur_cssize;
	u32 cs_order;
	int ret;
	int i;

	if (eb->is_42x && (cs_index > 7)) {
	dev_err(eb->dev,
	"invalid chipselect %u, we only support 0-7\n",
	cs_index);
	return;
	}
	if (eb->is_43x && (cs_index > 3)) {
	dev_err(eb->dev,
	"invalid chipselect %u, we only support 0-3\n",
	cs_index);
	return;
	}

	/* Several chip selects can be joined into one device */
	if (cs_size > IXP4XX_EXP_STRIDE)
	cur_cssize = IXP4XX_EXP_STRIDE;
	else
	cur_cssize = cs_size;


	/*
	* The following will read/modify/write the configuration for one
	* chipselect, attempting to leave the boot defaults in place unless
	* something is explicitly defined.
	*/
	regmap_read(eb->rmap, IXP4XX_EXP_TIMING_CS0 +
	IXP4XX_EXP_TIMING_STRIDE * cs_index, &cs_cfg);
	dev_info(eb->dev, "CS%d at %#08x, size %#08x, config before: %#08x\n",
	cs_index, eb->bus_base + IXP4XX_EXP_STRIDE * cs_index,
	cur_cssize, cs_cfg);

	/* Size set-up first align to 2^9 .. 2^24 */
	cur_cssize = roundup_pow_of_two(cur_cssize);
	if (cur_cssize < 512)
	cur_cssize = 512;
	cs_order = ilog2(cur_cssize);
	if (cs_order < 9 \|\| cs_order > 24) {
	dev_err(eb->dev, "illegal size order %d\n", cs_order);
	return;
	}
	dev_dbg(eb->dev, "CS%d size order: %d\n", cs_index, cs_order);
	cs_cfg &= ~(IXP4XX_EXP_SIZE_MASK);
	cs_cfg \|= ((cs_order - 9) << IXP4XX_EXP_SIZE_SHIFT);

	for (i = 0; i < ARRAY_SIZE(ixp4xx_exp_tim_props); i++) {
	const struct ixp4xx_exp_tim_prop *ip = &ixp4xx_exp_tim_props[i];

	/* All are regular u32 values */
	ret = of_property_read_u32(np, ip->prop, &val);
	if (ret)
	continue;

	/* Handle bools (single bits) first */
	if (ip->max == 1) {
	if (val)
	cs_cfg \|= ip->mask;
	else
	cs_cfg &= ~ip->mask;
	dev_info(eb->dev, "CS%d %s %s\n", cs_index,
	val ? "enabled" : "disabled",
	ip->prop);
	continue;
	}

	if (val > ip->max) {
	dev_err(eb->dev,
	"CS%d too high value for %s: %u, capped at %u\n",
	cs_index, ip->prop, val, ip->max);
	val = ip->max;
	}
	/* This assumes max value fills all the assigned bits (and it does) */
	cs_cfg &= ~ip->mask;
	cs_cfg \|= (val << ip->shift);
	dev_info(eb->dev, "CS%d set %s to %u\n", cs_index, ip->prop, val);
	}

	ret = of_property_read_u32(np, "intel,ixp4xx-eb-cycle-type", &val);
	if (!ret) {
	if (val > 3) {
	dev_err(eb->dev, "illegal cycle type %d\n", val);
	return;
	}
	dev_info(eb->dev, "CS%d set cycle type %d\n", cs_index, val);
	cs_cfg &= ~IXP4XX_EXP_CYC_TYPE_MASK;
	cs_cfg \|= val << IXP4XX_EXP_CYC_TYPE_SHIFT;
	}

	if (eb->is_43x) {
	/* Should always be zero */
	cs_cfg &= ~IXP4XX_EXP_WORD;
	/*
	* This bit for Intel strata flash is currently unused, but let's
	* report it if we find one.
	*/
	if (cs_cfg & IXP43X_EXP_SYNC_INTEL)
	dev_info(eb->dev, "claims to be Intel strata flash\n");
	}
	cs_cfg \|= IXP4XX_EXP_CS_EN;

	regmap_write(eb->rmap,
	IXP4XX_EXP_TIMING_CS0 + IXP4XX_EXP_TIMING_STRIDE * cs_index,
	cs_cfg);
	dev_info(eb->dev, "CS%d wrote %#08x into CS config\n", cs_index, cs_cfg);

	/*
	* If several chip selects are joined together into one big
	* device area, we call ourselves recursively for each successive
	* chip select. For a 32MB flash chip this results in two calls
	* for example.
	*/
	if (cs_size > IXP4XX_EXP_STRIDE)
	ixp4xx_exp_setup_chipselect(eb, np,
	cs_index + 1,
	cs_size - IXP4XX_EXP_STRIDE);
	}

	static void ixp4xx_exp_setup_child(struct ixp4xx_eb *eb,
	struct device_node *np)
	{
	u32 cs_sizes[IXP4XX_EXP_NUM_CS];
	int num_regs;
	u32 csindex;
	u32 cssize;
	int ret;
	int i;

	num_regs = of_property_count_elems_of_size(np, "reg", IXP4XX_OF_REG_SIZE);
	if (num_regs <= 0)
	return;
	dev_dbg(eb->dev, "child %s has %d register sets\n",
	of_node_full_name(np), num_regs);

	for (csindex = 0; csindex < IXP4XX_EXP_NUM_CS; csindex++)
	cs_sizes[csindex] = 0;

	for (i = 0; i < num_regs; i++) {
	u32 rbase, rsize;

	ret = of_property_read_u32_index(np, "reg",
	i * IXP4XX_OF_REG_SIZE, &csindex);
	if (ret)
	break;
	ret = of_property_read_u32_index(np, "reg",
	i * IXP4XX_OF_REG_SIZE + 1, &rbase);
	if (ret)
	break;
	ret = of_property_read_u32_index(np, "reg",
	i * IXP4XX_OF_REG_SIZE + 2, &rsize);
	if (ret)
	break;

	if (csindex >= IXP4XX_EXP_NUM_CS) {
	dev_err(eb->dev, "illegal CS %d\n", csindex);
	continue;
	}
	/*
	* The memory window always starts from CS base so we need to add
	* the start and size to get to the size from the start of the CS
	* base. For example if CS0 is at 0x50000000 and the reg is
	* <0 0xe40000 0x40000> the size is e80000.
	*
	* Roof this if we have several regs setting the same CS.
	*/
	cssize = rbase + rsize;
	dev_dbg(eb->dev, "CS%d size %#08x\n", csindex, cssize);
	if (cs_sizes[csindex] < cssize)
	cs_sizes[csindex] = cssize;
	}

	for (csindex = 0; csindex < IXP4XX_EXP_NUM_CS; csindex++) {
	cssize = cs_sizes[csindex];
	if (!cssize)
	continue;
	/* Just this one, so set it up and return */
	ixp4xx_exp_setup_chipselect(eb, np, csindex, cssize);
	}
	}

	static int ixp4xx_exp_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct device_node *np = dev->of_node;
	struct ixp4xx_eb *eb;
	struct device_node *child;
	bool have_children = false;
	u32 val;
	int ret;

	eb = devm_kzalloc(dev, sizeof(*eb), GFP_KERNEL);
	if (!eb)
	return -ENOMEM;

	eb->dev = dev;
	eb->is_42x = of_device_is_compatible(np, "intel,ixp42x-expansion-bus-controller");
	eb->is_43x = of_device_is_compatible(np, "intel,ixp43x-expansion-bus-controller");

	eb->rmap = syscon_node_to_regmap(np);
	if (IS_ERR(eb->rmap))
	return dev_err_probe(dev, PTR_ERR(eb->rmap), "no regmap\n");

	/* We check that the regmap work only on first read */
	ret = regmap_read(eb->rmap, IXP4XX_EXP_CNFG0, &val);
	if (ret)
	return dev_err_probe(dev, ret, "cannot read regmap\n");
	if (val & IXP4XX_EXP_CNFG0_MEM_MAP)
	eb->bus_base = IXP4XX_EXP_BOOT_BASE;
	else
	eb->bus_base = IXP4XX_EXP_NORMAL_BASE;
	dev_info(dev, "expansion bus at %08x\n", eb->bus_base);

	if (eb->is_43x) {
	/* Check some fuses */
	regmap_read(eb->rmap, IXP43X_EXP_UNIT_FUSE_RESET, &val);
	switch (FIELD_GET(IXP43x_EXP_FUSE_SPEED_MASK, val)) {
	case 0:
	dev_info(dev, "IXP43x at 533 MHz\n");
	break;
	case 1:
	dev_info(dev, "IXP43x at 400 MHz\n");
	break;
	case 2:
	dev_info(dev, "IXP43x at 667 MHz\n");
	break;
	default:
	dev_info(dev, "IXP43x unknown speed\n");
	break;
	}
	}

	/* Walk over the child nodes and see what chipselects we use */
	for_each_available_child_of_node(np, child) {
	ixp4xx_exp_setup_child(eb, child);
	/* We have at least one child */
	have_children = true;
	}

	if (have_children)
	return of_platform_default_populate(np, NULL, dev);

	return 0;
	}

	static const struct of_device_id ixp4xx_exp_of_match[] = {
	{ .compatible = "intel,ixp42x-expansion-bus-controller", },
	{ .compatible = "intel,ixp43x-expansion-bus-controller", },
	{ .compatible = "intel,ixp45x-expansion-bus-controller", },
	{ .compatible = "intel,ixp46x-expansion-bus-controller", },
	{ }
	};

	static struct platform_driver ixp4xx_exp_driver = {
	.probe = ixp4xx_exp_probe,
	.driver = {
	.name = "intel-extbus",
	.of_match_table = ixp4xx_exp_of_match,
	},
	};
	module_platform_driver(ixp4xx_exp_driver);
	MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
	MODULE_DESCRIPTION("Intel IXP4xx external bus driver");
	MODULE_LICENSE("GPL");