bus: ti-sysc: Add minimal TI sysc interconnect target driver

We can handle the sysc interconnect target module in a generic way
for many TI SoCs. Initially let's just enable runtime PM with
autosuspend, and probe the children. This can already be used for
idling interconnect target modules that don't have any device driver
available for the child devices.

For now, the "ti,hwmods" custom binding is still required. That will
be eventually deprecated in later patches. And more features will be
added, such as parsing for sysc capabilities so we can continue
removing the legacy platform data.

Cc: Benoît Cousson <bcousson@baylibre.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Nishanth Menon <nm@ti.com>
Cc: Matthijs van Duin <matthijsvanduin@gmail.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Peter Ujfalusi <peter.ujfalusi@ti.com>
Cc: Sakari Ailus <sakari.ailus@iki.fi>
Cc: Tero Kristo <t-kristo@ti.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mach-omap2/Kconfig

@@ -104,6 +104,7 @@ config ARCH_OMAP2PLUS
 	select OMAP_GPMC
 	select PINCTRL
 	select SOC_BUS
+	select TI_SYSC
 	select OMAP_IRQCHIP
 	select CLKSRC_TI_32K
 	help

drivers/bus/Kconfig

@@ -157,6 +157,13 @@ config TEGRA_GMI
 	  Driver for the Tegra Generic Memory Interface bus which can be used
 	  to attach devices such as NOR, UART, FPGA and more.
 
+config TI_SYSC
+	bool "TI sysc interconnect target module driver"
+	depends on ARCH_OMAP2PLUS
+	help
+	  Generic driver for Texas Instruments interconnect target module
+	  found on many TI SoCs.
+
 config UNIPHIER_SYSTEM_BUS
 	tristate "UniPhier System Bus driver"
 	depends on ARCH_UNIPHIER && OF

drivers/bus/Makefile

@@ -20,6 +20,7 @@ obj-$(CONFIG_SUNXI_RSB)		+= sunxi-rsb.o
 obj-$(CONFIG_SIMPLE_PM_BUS)	+= simple-pm-bus.o
 obj-$(CONFIG_TEGRA_ACONNECT)	+= tegra-aconnect.o
 obj-$(CONFIG_TEGRA_GMI)		+= tegra-gmi.o
+obj-$(CONFIG_TI_SYSC)		+= ti-sysc.o
 obj-$(CONFIG_UNIPHIER_SYSTEM_BUS)	+= uniphier-system-bus.o
 obj-$(CONFIG_VEXPRESS_CONFIG)	+= vexpress-config.o
 

drivers/bus/ti-sysc.c

+/*
+ * ti-sysc.c - Texas Instruments sysc interconnect target driver
+ *
+ * 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 "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+
+enum sysc_registers {
+	SYSC_REVISION,
+	SYSC_SYSCONFIG,
+	SYSC_SYSSTATUS,
+	SYSC_MAX_REGS,
+};
+
+static const char * const reg_names[] = { "rev", "sysc", "syss", };
+
+enum sysc_clocks {
+	SYSC_FCK,
+	SYSC_ICK,
+	SYSC_MAX_CLOCKS,
+};
+
+static const char * const clock_names[] = { "fck", "ick", };
+
+/**
+ * struct sysc - TI sysc interconnect target module registers and capabilities
+ * @dev: struct device pointer
+ * @module_pa: physical address of the interconnect target module
+ * @module_size: size of the interconnect target module
+ * @module_va: virtual address of the interconnect target module
+ * @offsets: register offsets from module base
+ * @clocks: clocks used by the interconnect target module
+ * @legacy_mode: configured for legacy mode if set
+ */
+struct sysc {
+	struct device *dev;
+	u64 module_pa;
+	u32 module_size;
+	void __iomem *module_va;
+	int offsets[SYSC_MAX_REGS];
+	struct clk *clocks[SYSC_MAX_CLOCKS];
+	const char *legacy_mode;
+};
+
+static u32 sysc_read_revision(struct sysc *ddata)
+{
+	return readl_relaxed(ddata->module_va +
+			     ddata->offsets[SYSC_REVISION]);
+}
+
+static int sysc_get_one_clock(struct sysc *ddata,
+			      enum sysc_clocks index)
+{
+	const char *name;
+	int error;
+
+	switch (index) {
+	case SYSC_FCK:
+		break;
+	case SYSC_ICK:
+		break;
+	default:
+		return -EINVAL;
+	}
+	name = clock_names[index];
+
+	ddata->clocks[index] = devm_clk_get(ddata->dev, name);
+	if (IS_ERR(ddata->clocks[index])) {
+		if (PTR_ERR(ddata->clocks[index]) == -ENOENT)
+			return 0;
+
+		dev_err(ddata->dev, "clock get error for %s: %li\n",
+			name, PTR_ERR(ddata->clocks[index]));
+
+		return PTR_ERR(ddata->clocks[index]);
+	}
+
+	error = clk_prepare(ddata->clocks[index]);
+	if (error) {
+		dev_err(ddata->dev, "clock prepare error for %s: %i\n",
+			name, error);
+
+		return error;
+	}
+
+	return 0;
+}
+
+static int sysc_get_clocks(struct sysc *ddata)
+{
+	int i, error;
+
+	if (ddata->legacy_mode)
+		return 0;
+
+	for (i = 0; i < SYSC_MAX_CLOCKS; i++) {
+		error = sysc_get_one_clock(ddata, i);
+		if (error && error != -ENOENT)
+			return error;
+	}
+
+	return 0;
+}
+
+/**
+ * sysc_parse_and_check_child_range - parses module IO region from ranges
+ * @ddata: device driver data
+ *
+ * In general we only need rev, syss, and sysc registers and not the whole
+ * module range. But we do want the offsets for these registers from the
+ * module base. This allows us to check them against the legacy hwmod
+ * platform data. Let's also check the ranges are configured properly.
+ */
+static int sysc_parse_and_check_child_range(struct sysc *ddata)
+{
+	struct device_node *np = ddata->dev->of_node;
+	const __be32 *ranges;
+	u32 nr_addr, nr_size;
+	int len, error;
+
+	ranges = of_get_property(np, "ranges", &len);
+	if (!ranges) {
+		dev_err(ddata->dev, "missing ranges for %pOF\n", np);
+
+		return -ENOENT;
+	}
+
+	len /= sizeof(*ranges);
+
+	if (len < 3) {
+		dev_err(ddata->dev, "incomplete ranges for %pOF\n", np);
+
+		return -EINVAL;
+	}
+
+	error = of_property_read_u32(np, "#address-cells", &nr_addr);
+	if (error)
+		return -ENOENT;
+
+	error = of_property_read_u32(np, "#size-cells", &nr_size);
+	if (error)
+		return -ENOENT;
+
+	if (nr_addr != 1 || nr_size != 1) {
+		dev_err(ddata->dev, "invalid ranges for %pOF\n", np);
+
+		return -EINVAL;
+	}
+
+	ranges++;
+	ddata->module_pa = of_translate_address(np, ranges++);
+	ddata->module_size = be32_to_cpup(ranges);
+
+	dev_dbg(ddata->dev, "interconnect target 0x%llx size 0x%x for %pOF\n",
+		ddata->module_pa, ddata->module_size, np);
+
+	return 0;
+}
+
+/**
+ * sysc_check_one_child - check child configuration
+ * @ddata: device driver data
+ * @np: child device node
+ *
+ * Let's avoid messy situations where we have new interconnect target
+ * node but children have "ti,hwmods". These belong to the interconnect
+ * target node and are managed by this driver.
+ */
+static int sysc_check_one_child(struct sysc *ddata,
+				struct device_node *np)
+{
+	const char *name;
+
+	name = of_get_property(np, "ti,hwmods", NULL);
+	if (name)
+		dev_warn(ddata->dev, "really a child ti,hwmods property?");
+
+	return 0;
+}
+
+static int sysc_check_children(struct sysc *ddata)
+{
+	struct device_node *child;
+	int error;
+
+	for_each_child_of_node(ddata->dev->of_node, child) {
+		error = sysc_check_one_child(ddata, child);
+		if (error)
+			return error;
+	}
+
+	return 0;
+}
+
+/**
+ * sysc_parse_one - parses the interconnect target module registers
+ * @ddata: device driver data
+ * @reg: register to parse
+ */
+static int sysc_parse_one(struct sysc *ddata, enum sysc_registers reg)
+{
+	struct resource *res;
+	const char *name;
+
+	switch (reg) {
+	case SYSC_REVISION:
+	case SYSC_SYSCONFIG:
+	case SYSC_SYSSTATUS:
+		name = reg_names[reg];
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	res = platform_get_resource_byname(to_platform_device(ddata->dev),
+					   IORESOURCE_MEM, name);
+	if (!res) {
+		dev_dbg(ddata->dev, "has no %s register\n", name);
+		ddata->offsets[reg] = -ENODEV;
+
+		return 0;
+	}
+
+	ddata->offsets[reg] = res->start - ddata->module_pa;
+
+	return 0;
+}
+
+static int sysc_parse_registers(struct sysc *ddata)
+{
+	int i, error;
+
+	for (i = 0; i < SYSC_MAX_REGS; i++) {
+		error = sysc_parse_one(ddata, i);
+		if (error)
+			return error;
+	}
+
+	return 0;
+}
+
+/**
+ * sysc_check_registers - check for misconfigured register overlaps
+ * @ddata: device driver data
+ */
+static int sysc_check_registers(struct sysc *ddata)
+{
+	int i, j, nr_regs = 0, nr_matches = 0;
+
+	for (i = 0; i < SYSC_MAX_REGS; i++) {
+		if (ddata->offsets[i] < 0)
+			continue;
+
+		if (ddata->offsets[i] > (ddata->module_size - 4)) {
+			dev_err(ddata->dev, "register outside module range");
+
+				return -EINVAL;
+		}
+
+		for (j = 0; j < SYSC_MAX_REGS; j++) {
+			if (ddata->offsets[j] < 0)
+				continue;
+
+			if (ddata->offsets[i] == ddata->offsets[j])
+				nr_matches++;
+		}
+		nr_regs++;
+	}
+
+	if (nr_regs < 1) {
+		dev_err(ddata->dev, "missing registers\n");
+
+		return -EINVAL;
+	}
+
+	if (nr_matches > nr_regs) {
+		dev_err(ddata->dev, "overlapping registers: (%i/%i)",
+			nr_regs, nr_matches);
+
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/**
+ * syc_ioremap - ioremap register space for the interconnect target module
+ * @ddata: deviec driver data
+ *
+ * Note that the interconnect target module registers can be anywhere
+ * within the first child device address space. For example, SGX has
+ * them at offset 0x1fc00 in the 32MB module address space. We just
+ * what we need around the interconnect target module registers.
+ */
+static int sysc_ioremap(struct sysc *ddata)
+{
+	u32 size = 0;
+
+	if (ddata->offsets[SYSC_SYSSTATUS] >= 0)
+		size = ddata->offsets[SYSC_SYSSTATUS];
+	else if (ddata->offsets[SYSC_SYSCONFIG] >= 0)
+		size = ddata->offsets[SYSC_SYSCONFIG];
+	else if (ddata->offsets[SYSC_REVISION] >= 0)
+		size = ddata->offsets[SYSC_REVISION];
+	else
+		return -EINVAL;
+
+	size &= 0xfff00;
+	size += SZ_256;
+
+	ddata->module_va = devm_ioremap(ddata->dev,
+					ddata->module_pa,
+					size);
+	if (!ddata->module_va)
+		return -EIO;
+
+	return 0;
+}
+
+/**
+ * sysc_map_and_check_registers - ioremap and check device registers
+ * @ddata: device driver data
+ */
+static int sysc_map_and_check_registers(struct sysc *ddata)
+{
+	int error;
+
+	error = sysc_parse_and_check_child_range(ddata);
+	if (error)
+		return error;
+
+	error = sysc_check_children(ddata);
+	if (error)
+		return error;
+
+	error = sysc_parse_registers(ddata);
+	if (error)
+		return error;
+
+	error = sysc_ioremap(ddata);
+	if (error)
+		return error;
+
+	error = sysc_check_registers(ddata);
+	if (error)
+		return error;
+
+	return 0;
+}
+
+/**
+ * sysc_show_rev - read and show interconnect target module revision
+ * @bufp: buffer to print the information to
+ * @ddata: device driver data
+ */
+static int sysc_show_rev(char *bufp, struct sysc *ddata)
+{
+	int error, len;
+
+	if (ddata->offsets[SYSC_REVISION] < 0)
+		return sprintf(bufp, ":NA");
+
+	error = pm_runtime_get_sync(ddata->dev);
+	if (error < 0) {
+		pm_runtime_put_noidle(ddata->dev);
+
+		return 0;
+	}
+
+	len = sprintf(bufp, ":%08x", sysc_read_revision(ddata));
+
+	pm_runtime_mark_last_busy(ddata->dev);
+	pm_runtime_put_autosuspend(ddata->dev);
+
+	return len;
+}
+
+static int sysc_show_reg(struct sysc *ddata,
+			 char *bufp, enum sysc_registers reg)
+{
+	if (ddata->offsets[reg] < 0)
+		return sprintf(bufp, ":NA");
+
+	return sprintf(bufp, ":%x", ddata->offsets[reg]);
+}
+
+/**
+ * sysc_show_registers - show information about interconnect target module
+ * @ddata: device driver data
+ */
+static void sysc_show_registers(struct sysc *ddata)
+{
+	char buf[128];
+	char *bufp = buf;
+	int i;
+
+	for (i = 0; i < SYSC_MAX_REGS; i++)
+		bufp += sysc_show_reg(ddata, bufp, i);
+
+	bufp += sysc_show_rev(bufp, ddata);
+
+	dev_dbg(ddata->dev, "%llx:%x%s\n",
+		ddata->module_pa, ddata->module_size,
+		buf);
+}
+
+static int sysc_runtime_suspend(struct device *dev)
+{
+	struct sysc *ddata;
+	int i;
+
+	ddata = dev_get_drvdata(dev);
+
+	if (ddata->legacy_mode)
+		return 0;
+
+	for (i = 0; i < SYSC_MAX_CLOCKS; i++) {
+		if (IS_ERR_OR_NULL(ddata->clocks[i]))
+			continue;
+		clk_disable(ddata->clocks[i]);
+	}
+
+	return 0;
+}
+
+static int sysc_runtime_resume(struct device *dev)
+{
+	struct sysc *ddata;
+	int i, error;
+
+	ddata = dev_get_drvdata(dev);
+
+	if (ddata->legacy_mode)
+		return 0;
+
+	for (i = 0; i < SYSC_MAX_CLOCKS; i++) {
+		if (IS_ERR_OR_NULL(ddata->clocks[i]))
+			continue;
+		error = clk_enable(ddata->clocks[i]);
+		if (error)
+			return error;
+	}
+
+	return 0;
+}
+
+static const struct dev_pm_ops sysc_pm_ops = {
+	SET_RUNTIME_PM_OPS(sysc_runtime_suspend,
+			   sysc_runtime_resume,
+			   NULL)
+};
+
+static void sysc_unprepare(struct sysc *ddata)
+{
+	int i;
+
+	for (i = 0; i < SYSC_MAX_CLOCKS; i++) {
+		if (!IS_ERR_OR_NULL(ddata->clocks[i]))
+			clk_unprepare(ddata->clocks[i]);
+	}
+}
+
+static int sysc_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct sysc *ddata;
+	int error;
+
+	ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
+	if (!ddata)
+		return -ENOMEM;
+
+	ddata->dev = &pdev->dev;
+	ddata->legacy_mode = of_get_property(np, "ti,hwmods", NULL);
+
+	error = sysc_get_clocks(ddata);
+	if (error)
+		return error;
+
+	error = sysc_map_and_check_registers(ddata);
+	if (error)
+		goto unprepare;
+
+	platform_set_drvdata(pdev, ddata);
+
+	pm_runtime_enable(ddata->dev);
+	error = pm_runtime_get_sync(ddata->dev);
+	if (error < 0) {
+		pm_runtime_put_noidle(ddata->dev);
+		pm_runtime_disable(ddata->dev);
+		goto unprepare;
+	}
+
+	pm_runtime_use_autosuspend(ddata->dev);
+
+	sysc_show_registers(ddata);
+
+	error = of_platform_populate(ddata->dev->of_node,
+				     NULL, NULL, ddata->dev);
+	if (error)
+		goto err;
+
+	pm_runtime_mark_last_busy(ddata->dev);
+	pm_runtime_put_autosuspend(ddata->dev);
+
+	return 0;
+
+err:
+	pm_runtime_dont_use_autosuspend(&pdev->dev);
+	pm_runtime_put_sync(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+unprepare:
+	sysc_unprepare(ddata);
+
+	return error;
+}
+
+static const struct of_device_id sysc_match[] = {
+	{ .compatible = "ti,sysc-omap2" },
+	{ .compatible = "ti,sysc-omap4" },
+	{ .compatible = "ti,sysc-omap4-simple" },
+	{ .compatible = "ti,sysc-omap3430-sr" },
+	{ .compatible = "ti,sysc-omap3630-sr" },
+	{ .compatible = "ti,sysc-omap4-sr" },
+	{ .compatible = "ti,sysc-omap3-sham" },
+	{ .compatible = "ti,sysc-omap-aes" },
+	{ .compatible = "ti,sysc-mcasp" },
+	{ .compatible = "ti,sysc-usb-host-fs" },
+	{  },
+};
+MODULE_DEVICE_TABLE(of, sysc_match);
+
+static struct platform_driver sysc_driver = {
+	.probe		= sysc_probe,
+	.driver         = {
+		.name   = "ti-sysc",
+		.of_match_table	= sysc_match,
+		.pm = &sysc_pm_ops,
+	},
+};
+module_platform_driver(sysc_driver);
+
+MODULE_DESCRIPTION("TI sysc interconnect target driver");
+MODULE_LICENSE("GPL v2");