Merge tag 'ixp4xx-drivers-arm-soc-v5.15-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-nomadik into arm/drivers

IXP4xx driver updates for modernizing the IXP4xx platforms,
taregeted for v5.15:

- Add DT bindings to the expansion bus and PATA libata driver.

- Add a new expansion bus driver.

- Rewrite the watchdog driver to use the watchdog core and
  spawn from the timer (clocksource) driver.

- Refactor the PATA/libata driver to probe from the device
  tree and use the expansion bus driver to manipulate chip
  select timings directly.

* tag 'ixp4xx-drivers-arm-soc-v5.15-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-nomadik:
  pata: ixp4xx: Rewrite to use device tree
  pata: ixp4xx: Add DT bindings
  pata: ixp4xx: Refer to cmd and ctl rather than csN
  pata: ixp4xx: Use IS_ENABLED() to determine endianness
  pata: ixp4xx: Use local dev variable
  watchdog: ixp4xx: Rewrite driver to use core
  bus: ixp4xx: Add a driver for IXP4xx expansion bus
  bus: ixp4xx: Add DT bindings for the IXP4xx expansion bus

Link: https://lore.kernel.org/r/CACRpkdZaCosXsgp02nuUbd_nEvdxm5-z0+d0oSA97UTWQ0RQQg@mail.gmail.com
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

3 files changed, 441 insertions, 0 deletions

diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index e7f7eee6ee9a..a5b96f3aad67 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -95,6 +95,17 @@ config IMX_WEIM
 	  The WEIM(Wireless External Interface Module) works like a bus.
 	  You can attach many different devices on it, such as NOR, onenand.
 
+config INTEL_IXP4XX_EB
+	bool "Intel IXP4xx expansion bus interface driver"
+	depends on HAS_IOMEM
+	depends on ARCH_IXP4XX || COMPILE_TEST
+	default ARCH_IXP4XX
+	select MFD_SYSCON
+	help
+	  Driver for the Intel IXP4xx expansion bus interface. The driver is
+	  needed to set up various chip select configuration parameters before
+	  devices on the expansion bus can be discovered.
+
 config MIPS_CDMM
 	bool "MIPS Common Device Memory Map (CDMM) Driver"
 	depends on CPU_MIPSR2 || CPU_MIPSR5
diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
index 397e35392bff..1c29c5e8ffb8 100644
--- a/drivers/bus/Makefile
+++ b/drivers/bus/Makefile
@@ -16,6 +16,7 @@ obj-$(CONFIG_FSL_MC_BUS)	+= fsl-mc/
 obj-$(CONFIG_BT1_APB)		+= bt1-apb.o
 obj-$(CONFIG_BT1_AXI)		+= bt1-axi.o
 obj-$(CONFIG_IMX_WEIM)		+= imx-weim.o
+obj-$(CONFIG_INTEL_IXP4XX_EB)	+= intel-ixp4xx-eb.o
 obj-$(CONFIG_MIPS_CDMM)		+= mips_cdmm.o
 obj-$(CONFIG_MVEBU_MBUS) 	+= mvebu-mbus.o
 
diff --git a/drivers/bus/intel-ixp4xx-eb.c b/drivers/bus/intel-ixp4xx-eb.c
new file mode 100644
index 000000000000..9acd00da413c
--- /dev/null
+++ b/drivers/bus/intel-ixp4xx-eb.c
@@ -0,0 +1,429 @@
+// 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 */
+#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 IXP42X_RESERVED			(BIT(30)|IXP4XX_EXP_CNFG_0|BIT(8)|BIT(7)|IXP4XX_EXP_WORD)
+#define IXP43X_RESERVED			(BIT(30)|IXP4XX_EXP_CNFG_0|BIT(5)|IXP4XX_EXP_WORD)
+
+#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_42x)
+		cs_cfg &= ~IXP42X_RESERVED;
+	if (eb->is_43x) {
+		cs_cfg &= ~IXP43X_RESERVED;
+		/*
+		 * 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)
+		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");