[2/2,v5] bus: qcom: add EBI2 driver

diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index 3b205e212337..952eeebe0b79 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -108,6 +108,13 @@  config OMAP_OCP2SCP
 	  OCP2SCP and in OMAP5, both USB PHY and SATA PHY is connected via
 	  OCP2SCP.
 
+config QCOM_EBI2
+	bool "Qualcomm External Bus Interface 2 (EBI2)"
+	help
+	  Say y here to enable support for the Qualcomm External Bus
+	  Interface 2, which can be used to connect things like NAND Flash,
+	  SRAM, ethernet adapters, FPGAs and LCD displays.
+
 config SIMPLE_PM_BUS
 	bool "Simple Power-Managed Bus Driver"
 	depends on OF && PM
diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
index ac84cc4348e3..c6cfa6b2606e 100644
--- a/drivers/bus/Makefile
+++ b/drivers/bus/Makefile
@@ -15,6 +15,7 @@  obj-$(CONFIG_MVEBU_MBUS) 	+= mvebu-mbus.o
 obj-$(CONFIG_OMAP_INTERCONNECT)	+= omap_l3_smx.o omap_l3_noc.o
 
 obj-$(CONFIG_OMAP_OCP2SCP)	+= omap-ocp2scp.o
+obj-$(CONFIG_QCOM_EBI2)		+= qcom-ebi2.o
 obj-$(CONFIG_SUNXI_RSB)		+= sunxi-rsb.o
 obj-$(CONFIG_SIMPLE_PM_BUS)	+= simple-pm-bus.o
 obj-$(CONFIG_TEGRA_ACONNECT)	+= tegra-aconnect.o
diff --git a/drivers/bus/qcom-ebi2.c b/drivers/bus/qcom-ebi2.c
new file mode 100644
index 000000000000..a6444244c411
--- /dev/null
+++ b/drivers/bus/qcom-ebi2.c
@@ -0,0 +1,408 @@ 
+/*
+ * Qualcomm External Bus Interface 2 (EBI2) driver
+ * an older version of the Qualcomm Parallel Interface Controller (QPIC)
+ *
+ * Copyright (C) 2016 Linaro Ltd.
+ *
+ * Author: Linus Walleij <linus.walleij@linaro.org>
+ *
+ * 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.
+ *
+ * See the device tree bindings for this block for more details on the
+ * hardware.
+ */
+
+#include <linux/module.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/bitops.h>
+
+/*
+ * CS0, CS1, CS4 and CS5 are two bits wide, CS2 and CS3 are one bit.
+ */
+#define EBI2_CS0_ENABLE_MASK BIT(0)|BIT(1)
+#define EBI2_CS1_ENABLE_MASK BIT(2)|BIT(3)
+#define EBI2_CS2_ENABLE_MASK BIT(4)
+#define EBI2_CS3_ENABLE_MASK BIT(5)
+#define EBI2_CS4_ENABLE_MASK BIT(6)|BIT(7)
+#define EBI2_CS5_ENABLE_MASK BIT(8)|BIT(9)
+#define EBI2_CSN_MASK GENMASK(9, 0)
+
+#define EBI2_XMEM_CFG 0x0000 /* Power management etc */
+
+/*
+ * SLOW CSn CFG
+ *
+ * Bits 31-28: RECOVERY recovery cycles (0 = 1, 1 = 2 etc) this is the time the
+ *             memory continues to drive the data bus after OE is de-asserted.
+ *             Inserted when reading one CS and switching to another CS or read
+ *             followed by write on the same CS. Valid values 0 thru 15.
+ * Bits 27-24: WR_HOLD write hold cycles, these are extra cycles inserted after
+ *             every write minimum 1. The data out is driven from the time WE is
+ *             asserted until CS is asserted. With a hold of 1, the CS stays
+ *             active for 1 extra cycle etc. Valid values 0 thru 15.
+ * Bits 23-16: WR_DELTA initial latency for write cycles inserted for the first
+ *             write to a page or burst memory
+ * Bits 15-8:  RD_DELTA initial latency for read cycles inserted for the first
+ *             read to a page or burst memory
+ * Bits 7-4:   WR_WAIT number of wait cycles for every write access, 0=1 cycle
+ *             so 1 thru 16 cycles.
+ * Bits 3-0:   RD_WAIT number of wait cycles for every read access, 0=1 cycle
+ *             so 1 thru 16 cycles.
+ */
+#define EBI2_XMEM_CS0_SLOW_CFG 0x0008
+#define EBI2_XMEM_CS1_SLOW_CFG 0x000C
+#define EBI2_XMEM_CS2_SLOW_CFG 0x0010
+#define EBI2_XMEM_CS3_SLOW_CFG 0x0014
+#define EBI2_XMEM_CS4_SLOW_CFG 0x0018
+#define EBI2_XMEM_CS5_SLOW_CFG 0x001C
+
+#define EBI2_XMEM_RECOVERY_SHIFT	28
+#define EBI2_XMEM_WR_HOLD_SHIFT		24
+#define EBI2_XMEM_WR_DELTA_SHIFT	16
+#define EBI2_XMEM_RD_DELTA_SHIFT	8
+#define EBI2_XMEM_WR_WAIT_SHIFT		4
+#define EBI2_XMEM_RD_WAIT_SHIFT		0
+
+/*
+ * FAST CSn CFG
+ * Bits 31-28: ?
+ * Bits 27-24: RD_HOLD: the length in cycles of the first segment of a read
+ *             transfer. For a single read trandfer this will be the time
+ *             from CS assertion to OE assertion.
+ * Bits 18-24: ?
+ * Bits 17-16: ADV_OE_RECOVERY, the number of cycles elapsed before an OE
+ *             assertion, with respect to the cycle where ADV is asserted.
+ *             2 means 2 cycles between ADV and OE. Values 0, 1, 2 or 3.
+ * Bits 5:     ADDR_HOLD_ENA, The address is held for an extra cycle to meet
+ *             hold time requirements with ADV assertion.
+ *
+ * The manual mentions "write precharge cycles" and "precharge cycles".
+ * We have not been able to figure out which bit fields these correspond to
+ * in the hardware, or what valid values exist. The current hypothesis is that
+ * this is something just used on the FAST chip selects. There is also a "byte
+ * device enable" flag somewhere for 8bit memories.
+ */
+#define EBI2_XMEM_CS0_FAST_CFG 0x0028
+#define EBI2_XMEM_CS1_FAST_CFG 0x002C
+#define EBI2_XMEM_CS2_FAST_CFG 0x0030
+#define EBI2_XMEM_CS3_FAST_CFG 0x0034
+#define EBI2_XMEM_CS4_FAST_CFG 0x0038
+#define EBI2_XMEM_CS5_FAST_CFG 0x003C
+
+#define EBI2_XMEM_RD_HOLD_SHIFT		24
+#define EBI2_XMEM_ADV_OE_RECOVERY_SHIFT	16
+#define EBI2_XMEM_ADDR_HOLD_ENA_SHIFT	5
+
+/**
+ * struct cs_data - struct with info on a chipselect setting
+ * @enable_mask: mask to enable the chipselect in the EBI2 config
+ * @slow_cfg0: offset to XMEMC slow CS config
+ * @fast_cfg1: offset to XMEMC fast CS config
+ */
+struct cs_data {
+	u32 enable_mask;
+	u16 slow_cfg;
+	u16 fast_cfg;
+};
+
+static const struct cs_data cs_info[] = {
+	{
+		/* CS0 */
+		.enable_mask = EBI2_CS0_ENABLE_MASK,
+		.slow_cfg = EBI2_XMEM_CS0_SLOW_CFG,
+		.fast_cfg = EBI2_XMEM_CS0_FAST_CFG,
+	},
+	{
+		/* CS1 */
+		.enable_mask = EBI2_CS1_ENABLE_MASK,
+		.slow_cfg = EBI2_XMEM_CS1_SLOW_CFG,
+		.fast_cfg = EBI2_XMEM_CS1_FAST_CFG,
+	},
+	{
+		/* CS2 */
+		.enable_mask = EBI2_CS2_ENABLE_MASK,
+		.slow_cfg = EBI2_XMEM_CS2_SLOW_CFG,
+		.fast_cfg = EBI2_XMEM_CS2_FAST_CFG,
+	},
+	{
+		/* CS3 */
+		.enable_mask = EBI2_CS3_ENABLE_MASK,
+		.slow_cfg = EBI2_XMEM_CS3_SLOW_CFG,
+		.fast_cfg = EBI2_XMEM_CS3_FAST_CFG,
+	},
+	{
+		/* CS4 */
+		.enable_mask = EBI2_CS4_ENABLE_MASK,
+		.slow_cfg = EBI2_XMEM_CS4_SLOW_CFG,
+		.fast_cfg = EBI2_XMEM_CS4_FAST_CFG,
+	},
+	{
+		/* CS5 */
+		.enable_mask = EBI2_CS5_ENABLE_MASK,
+		.slow_cfg = EBI2_XMEM_CS5_SLOW_CFG,
+		.fast_cfg = EBI2_XMEM_CS5_FAST_CFG,
+	},
+};
+
+/**
+ * struct ebi2_xmem_prop - describes an XMEM config property
+ * @prop: the device tree binding name
+ * @max: maximum value for the property
+ * @slowreg: true if this property is in the SLOW CS config register
+ * else it is assumed to be in the FAST config register
+ * @shift: the bit field start in the SLOW or FAST register for this
+ * property
+ */
+struct ebi2_xmem_prop {
+	const char *prop;
+	u32 max;
+	bool slowreg;
+	u16 shift;
+};
+
+static const struct ebi2_xmem_prop xmem_props[] = {
+	{
+		.prop = "qcom,xmem-recovery-cycles",
+		.max = 15,
+		.slowreg = true,
+		.shift = EBI2_XMEM_RECOVERY_SHIFT,
+	},
+	{
+		.prop = "qcom,xmem-write-hold-cycles",
+		.max = 15,
+		.slowreg = true,
+		.shift = EBI2_XMEM_WR_HOLD_SHIFT,
+	},
+	{
+		.prop = "qcom,xmem-write-delta-cycles",
+		.max = 255,
+		.slowreg = true,
+		.shift = EBI2_XMEM_WR_DELTA_SHIFT,
+	},
+	{
+		.prop = "qcom,xmem-read-delta-cycles",
+		.max = 255,
+		.slowreg = true,
+		.shift = EBI2_XMEM_RD_DELTA_SHIFT,
+	},
+	{
+		.prop = "qcom,xmem-write-wait-cycles",
+		.max = 15,
+		.slowreg = true,
+		.shift = EBI2_XMEM_WR_WAIT_SHIFT,
+	},
+	{
+		.prop = "qcom,xmem-read-wait-cycles",
+		.max = 15,
+		.slowreg = true,
+		.shift = EBI2_XMEM_RD_WAIT_SHIFT,
+	},
+	{
+		.prop = "qcom,xmem-address-hold-enable",
+		.max = 1, /* boolean prop */
+		.slowreg = false,
+		.shift = EBI2_XMEM_ADDR_HOLD_ENA_SHIFT,
+	},
+	{
+		.prop = "qcom,xmem-adv-to-oe-recovery-cycles",
+		.max = 3,
+		.slowreg = false,
+		.shift = EBI2_XMEM_ADV_OE_RECOVERY_SHIFT,
+	},
+	{
+		.prop = "qcom,xmem-read-hold-cycles",
+		.max = 15,
+		.slowreg = false,
+		.shift = EBI2_XMEM_RD_HOLD_SHIFT,
+	},
+};
+
+static void qcom_ebi2_setup_chipselect(struct device_node *np,
+				       struct device *dev,
+				       void __iomem *ebi2_base,
+				       void __iomem *ebi2_xmem,
+				       u32 csindex)
+{
+	const struct cs_data *csd;
+	u32 slowcfg, fastcfg;
+	u32 val;
+	int ret;
+	int i;
+
+	csd = &cs_info[csindex];
+	val = readl(ebi2_base);
+	val |= csd->enable_mask;
+	writel(val, ebi2_base);
+	dev_dbg(dev, "enabled CS%u\n", csindex);
+
+	/* Next set up the XMEMC */
+	slowcfg = 0;
+	fastcfg = 0;
+
+	for (i = 0; i < ARRAY_SIZE(xmem_props); i++) {
+		const struct ebi2_xmem_prop *xp = &xmem_props[i];
+
+		/* All are regular u32 values */
+		ret = of_property_read_u32(np, xp->prop, &val);
+		if (ret) {
+			dev_dbg(dev, "could not read %s for CS%d\n",
+				xp->prop, csindex);
+			continue;
+		}
+
+		/* First check boolean props */
+		if (xp->max == 1 && val) {
+			if (xp->slowreg)
+				slowcfg |= BIT(xp->shift);
+			else
+				fastcfg |= BIT(xp->shift);
+			dev_dbg(dev, "set %s flag\n", xp->prop);
+			continue;
+		}
+
+		/* We're dealing with an u32 */
+		if (val > xp->max) {
+			dev_err(dev,
+				"too high value for %s: %u, capped at %u\n",
+				xp->prop, val, xp->max);
+			val = xp->max;
+		}
+		if (xp->slowreg)
+			slowcfg |= (val << xp->shift);
+		else
+			fastcfg |= (val << xp->shift);
+		dev_dbg(dev, "set %s to %u\n", xp->prop, val);
+	}
+
+	dev_info(dev, "CS%u: SLOW CFG 0x%08x, FAST CFG 0x%08x\n",
+		 csindex, slowcfg, fastcfg);
+
+	if (slowcfg)
+		writel(slowcfg, ebi2_xmem + csd->slow_cfg);
+	if (fastcfg)
+		writel(fastcfg, ebi2_xmem + csd->fast_cfg);
+}
+
+static int qcom_ebi2_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct device_node *child;
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	void __iomem *ebi2_base;
+	void __iomem *ebi2_xmem;
+	struct clk *ebi2xclk;
+	struct clk *ebi2clk;
+	bool have_children = false;
+	u32 val;
+	int ret;
+
+	ebi2xclk = devm_clk_get(dev, "ebi2x");
+	if (IS_ERR(ebi2xclk))
+		return PTR_ERR(ebi2xclk);
+
+	ret = clk_prepare_enable(ebi2xclk);
+	if (ret) {
+		dev_err(dev, "could not enable EBI2X clk (%d)\n", ret);
+		return ret;
+	}
+
+	ebi2clk = devm_clk_get(dev, "ebi2");
+	if (IS_ERR(ebi2clk)) {
+		ret = PTR_ERR(ebi2clk);
+		goto err_disable_2x_clk;
+	}
+
+	ret = clk_prepare_enable(ebi2clk);
+	if (ret) {
+		dev_err(dev, "could not enable EBI2 clk\n");
+		goto err_disable_2x_clk;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	ebi2_base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(ebi2_base)) {
+		ret = PTR_ERR(ebi2_base);
+		goto err_disable_clk;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	ebi2_xmem = devm_ioremap_resource(dev, res);
+	if (IS_ERR(ebi2_xmem)) {
+		ret = PTR_ERR(ebi2_xmem);
+		goto err_disable_clk;
+	}
+
+	/* Allegedly this turns the power save mode off */
+	writel(0UL, ebi2_xmem + EBI2_XMEM_CFG);
+
+	/* Disable all chipselects */
+	val = readl(ebi2_base);
+	val &= ~EBI2_CSN_MASK;
+	writel(val, ebi2_base);
+
+	/* Walk over the child nodes and see what chipselects we use */
+	for_each_available_child_of_node(np, child) {
+		u32 csindex;
+
+		/* Figure out the chipselect */
+		ret = of_property_read_u32(child, "reg", &csindex);
+		if (ret)
+			return ret;
+
+		if (csindex > 5) {
+			dev_err(dev,
+				"invalid chipselect %u, we only support 0-5\n",
+				csindex);
+			continue;
+		}
+
+		qcom_ebi2_setup_chipselect(child,
+					   dev,
+					   ebi2_base,
+					   ebi2_xmem,
+					   csindex);
+
+		/* We have at least one child */
+		have_children = true;
+	}
+
+	if (have_children)
+		return of_platform_default_populate(np, NULL, dev);
+	return 0;
+
+err_disable_clk:
+	clk_disable_unprepare(ebi2clk);
+err_disable_2x_clk:
+	clk_disable_unprepare(ebi2xclk);
+
+	return ret;
+}
+
+static const struct of_device_id qcom_ebi2_of_match[] = {
+	{ .compatible = "qcom,msm8660-ebi2", },
+	{ .compatible = "qcom,apq8060-ebi2", },
+	{ }
+};
+
+static struct platform_driver qcom_ebi2_driver = {
+	.probe = qcom_ebi2_probe,
+	.driver = {
+		.name = "qcom-ebi2",
+		.of_match_table = qcom_ebi2_of_match,
+	},
+};
+module_platform_driver(qcom_ebi2_driver);
+MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
+MODULE_DESCRIPTION("Qualcomm EBI2 driver");
+MODULE_LICENSE("GPL");