mfd: vexpress: Define the device as MFD cells

This patch - finally, after over 6 months! :-( - addresses
Samuel's request to split the vexpress-sysreg driver into
smaller portions and define the device in a form of MFD
cells:

* LEDs code has been completely removed and replaced with
  "gpio-leds" nodes in the tree (referencing dedicated
  GPIO subnodes in sysreg - bindings documentation updated);
  this also better fits the reality as some variants of the
  motherboard don't have all the LEDs populated

* syscfg bridge code has been extracted into a separate
  driver (placed in drivers/misc for no better place)

* all the ID & MISC registers are defined as sysconf
  making them available for other drivers should they need
  to use them (and also to the user via /sys/kernel/debug/regmap
  which can be helpful in platform debugging)

Signed-off-by: Pawel Moll <pawel.moll@arm.com>
Acked-by: Lee Jones <lee.jones@linaro.org>

3 files changed, 334 insertions, 0 deletions

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 8baff0effc7d..d9663ef90ce8 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -515,6 +515,15 @@ config SRAM
 	  the genalloc API. It is supposed to be used for small on-chip SRAM
 	  areas found on many SoCs.
 
+config VEXPRESS_SYSCFG
+	bool "Versatile Express System Configuration driver"
+	depends on VEXPRESS_CONFIG
+	default y
+	help
+	  ARM Ltd. Versatile Express uses specialised platform configuration
+	  bus. System Configuration interface is one of the possible means
+	  of generating transactions on this bus.
+
 source "drivers/misc/c2port/Kconfig"
 source "drivers/misc/eeprom/Kconfig"
 source "drivers/misc/cb710/Kconfig"
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 7eb4b69580c0..d59ce1261b38 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -55,3 +55,4 @@ obj-$(CONFIG_SRAM)		+= sram.o
 obj-y				+= mic/
 obj-$(CONFIG_GENWQE)		+= genwqe/
 obj-$(CONFIG_ECHO)		+= echo/
+obj-$(CONFIG_VEXPRESS_SYSCFG)	+= vexpress-syscfg.o
diff --git a/drivers/misc/vexpress-syscfg.c b/drivers/misc/vexpress-syscfg.c
new file mode 100644
index 000000000000..73068e50e56d
--- /dev/null
+++ b/drivers/misc/vexpress-syscfg.c
@@ -0,0 +1,324 @@
+/*
+ * 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) 2014 ARM Limited
+ */
+
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/syscore_ops.h>
+#include <linux/vexpress.h>
+
+
+#define SYS_CFGDATA		0x0
+
+#define SYS_CFGCTRL		0x4
+#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		0x8
+#define SYS_CFGSTAT_ERR		(1 << 1)
+#define SYS_CFGSTAT_COMPLETE	(1 << 0)
+
+
+struct vexpress_syscfg {
+	struct device *dev;
+	void __iomem *base;
+	struct list_head funcs;
+};
+
+struct vexpress_syscfg_func {
+	struct list_head list;
+	struct vexpress_syscfg *syscfg;
+	struct regmap *regmap;
+	int num_templates;
+	u32 template[0]; /* Keep it last! */
+};
+
+
+static int vexpress_syscfg_exec(struct vexpress_syscfg_func *func,
+		int index, bool write, u32 *data)
+{
+	struct vexpress_syscfg *syscfg = func->syscfg;
+	u32 command, status;
+	int tries;
+	long timeout;
+
+	if (WARN_ON(index > func->num_templates))
+		return -EINVAL;
+
+	command = readl(syscfg->base + SYS_CFGCTRL);
+	if (WARN_ON(command & SYS_CFGCTRL_START))
+		return -EBUSY;
+
+	command = func->template[index];
+	command |= SYS_CFGCTRL_START;
+	command |= write ? SYS_CFGCTRL_WRITE : 0;
+
+	/* Use a canary for reads */
+	if (!write)
+		*data = 0xdeadbeef;
+
+	dev_dbg(syscfg->dev, "func %p, command %x, data %x\n",
+			func, command, *data);
+	writel(*data, syscfg->base + SYS_CFGDATA);
+	writel(0, syscfg->base + SYS_CFGSTAT);
+	writel(command, syscfg->base + SYS_CFGCTRL);
+	mb();
+
+	/* The operation can take ages... Go to sleep, 100us initially */
+	tries = 100;
+	timeout = 100;
+	do {
+		if (!irqs_disabled()) {
+			set_current_state(TASK_INTERRUPTIBLE);
+			schedule_timeout(usecs_to_jiffies(timeout));
+			if (signal_pending(current))
+				return -EINTR;
+		} else {
+			udelay(timeout);
+		}
+
+		status = readl(syscfg->base + SYS_CFGSTAT);
+		if (status & SYS_CFGSTAT_ERR)
+			return -EFAULT;
+
+		if (timeout > 20)
+			timeout -= 20;
+	} while (--tries && !(status & SYS_CFGSTAT_COMPLETE));
+	if (WARN_ON_ONCE(!tries))
+		return -ETIMEDOUT;
+
+	if (!write) {
+		*data = readl(syscfg->base + SYS_CFGDATA);
+		dev_dbg(syscfg->dev, "func %p, read data %x\n", func, *data);
+	}
+
+	return 0;
+}
+
+static int vexpress_syscfg_read(void *context, unsigned int index,
+		unsigned int *val)
+{
+	struct vexpress_syscfg_func *func = context;
+
+	return vexpress_syscfg_exec(func, index, false, val);
+}
+
+static int vexpress_syscfg_write(void *context, unsigned int index,
+		unsigned int val)
+{
+	struct vexpress_syscfg_func *func = context;
+
+	return vexpress_syscfg_exec(func, index, true, &val);
+}
+
+struct regmap_config vexpress_syscfg_regmap_config = {
+	.lock = vexpress_config_lock,
+	.unlock = vexpress_config_unlock,
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_read = vexpress_syscfg_read,
+	.reg_write = vexpress_syscfg_write,
+	.reg_format_endian = REGMAP_ENDIAN_LITTLE,
+	.val_format_endian = REGMAP_ENDIAN_LITTLE,
+};
+
+
+static struct regmap *vexpress_syscfg_regmap_init(struct device *dev,
+		void *context)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct vexpress_syscfg *syscfg = context;
+	struct vexpress_syscfg_func *func;
+	struct property *prop;
+	const __be32 *val = NULL;
+	__be32 energy_quirk[4];
+	int num;
+	u32 site, position, dcc;
+	int i;
+
+	if (dev->of_node) {
+		int err = vexpress_config_get_topo(dev->of_node, &site,
+				&position, &dcc);
+
+		if (err)
+			return ERR_PTR(err);
+
+		prop = of_find_property(dev->of_node,
+				"arm,vexpress-sysreg,func", NULL);
+		if (!prop)
+			return ERR_PTR(-EINVAL);
+
+		num = prop->length / sizeof(u32) / 2;
+		val = prop->value;
+	} else {
+		if (pdev->num_resources != 1 ||
+				pdev->resource[0].flags != IORESOURCE_BUS)
+			return ERR_PTR(-EFAULT);
+
+		site = pdev->resource[0].start;
+		if (site == VEXPRESS_SITE_MASTER)
+			site = vexpress_config_get_master();
+		position = 0;
+		dcc = 0;
+		num = 1;
+	}
+
+	/*
+	 * "arm,vexpress-energy" function used to be described
+	 * by its first device only, now it requires both
+	 */
+	if (num == 1 && of_device_is_compatible(dev->of_node,
+			"arm,vexpress-energy")) {
+		num = 2;
+		energy_quirk[0] = *val;
+		energy_quirk[2] = *val++;
+		energy_quirk[1] = *val;
+		energy_quirk[3] = cpu_to_be32(be32_to_cpup(val) + 1);
+		val = energy_quirk;
+	}
+
+	func = kzalloc(sizeof(*func) + sizeof(*func->template) * num,
+			GFP_KERNEL);
+	if (!func)
+		return NULL;
+
+	func->syscfg = syscfg;
+	func->num_templates = num;
+
+	for (i = 0; i < num; i++) {
+		u32 function, device;
+
+		if (dev->of_node) {
+			function = be32_to_cpup(val++);
+			device = be32_to_cpup(val++);
+		} else {
+			function = pdev->resource[0].end;
+			device = pdev->id;
+		}
+
+		dev_dbg(dev, "func %p: %u/%u/%u/%u/%u\n",
+				func, site, position, dcc,
+				function, device);
+
+		func->template[i] = SYS_CFGCTRL_DCC(dcc);
+		func->template[i] |= SYS_CFGCTRL_SITE(site);
+		func->template[i] |= SYS_CFGCTRL_POSITION(position);
+		func->template[i] |= SYS_CFGCTRL_FUNC(function);
+		func->template[i] |= SYS_CFGCTRL_DEVICE(device);
+	}
+
+	vexpress_syscfg_regmap_config.max_register = num - 1;
+
+	func->regmap = regmap_init(dev, NULL, func,
+			&vexpress_syscfg_regmap_config);
+
+	if (IS_ERR(func->regmap))
+		kfree(func);
+	else
+		list_add(&func->list, &syscfg->funcs);
+
+	return func->regmap;
+}
+
+static void vexpress_syscfg_regmap_exit(struct regmap *regmap, void *context)
+{
+	struct vexpress_syscfg *syscfg = context;
+	struct vexpress_syscfg_func *func, *tmp;
+
+	regmap_exit(regmap);
+
+	list_for_each_entry_safe(func, tmp, &syscfg->funcs, list) {
+		if (func->regmap == regmap) {
+			list_del(&syscfg->funcs);
+			kfree(func);
+			break;
+		}
+	}
+}
+
+static struct vexpress_config_bridge_ops vexpress_syscfg_bridge_ops = {
+	.regmap_init = vexpress_syscfg_regmap_init,
+	.regmap_exit = vexpress_syscfg_regmap_exit,
+};
+
+
+/* Non-DT hack, to be gone... */
+static struct device *vexpress_syscfg_bridge;
+
+int vexpress_syscfg_device_register(struct platform_device *pdev)
+{
+	pdev->dev.parent = vexpress_syscfg_bridge;
+
+	return platform_device_register(pdev);
+}
+
+
+int vexpress_syscfg_probe(struct platform_device *pdev)
+{
+	struct vexpress_syscfg *syscfg;
+	struct resource *res;
+	struct device *bridge;
+
+	syscfg = devm_kzalloc(&pdev->dev, sizeof(*syscfg), GFP_KERNEL);
+	if (!syscfg)
+		return -ENOMEM;
+	syscfg->dev = &pdev->dev;
+	INIT_LIST_HEAD(&syscfg->funcs);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!devm_request_mem_region(&pdev->dev, res->start,
+			resource_size(res), pdev->name))
+		return -EBUSY;
+
+	syscfg->base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
+	if (!syscfg->base)
+		return -EFAULT;
+
+	/* Must use dev.parent (MFD), as that's where DT phandle points at... */
+	bridge = vexpress_config_bridge_register(pdev->dev.parent,
+			&vexpress_syscfg_bridge_ops, syscfg);
+	if (IS_ERR(bridge))
+		return PTR_ERR(bridge);
+
+	/* Non-DT case */
+	if (!pdev->dev.of_node)
+		vexpress_syscfg_bridge = bridge;
+
+	return 0;
+}
+
+static const struct platform_device_id vexpress_syscfg_id_table[] = {
+	{ "vexpress-syscfg", },
+	{},
+};
+
+static struct platform_driver vexpress_syscfg_driver = {
+	.driver.name = "vexpress-syscfg",
+	.id_table = vexpress_syscfg_id_table,
+	.probe = vexpress_syscfg_probe,
+};
+
+static int __init vexpress_syscfg_init(void)
+{
+	return platform_driver_register(&vexpress_syscfg_driver);
+}
+core_initcall(vexpress_syscfg_init);