mfd: Add syscon driver based on regmap

Add regmap based syscon driver.
This is usually used for access misc bits in registers which does not belong
to a specific module, for example, IMX IOMUXC GPR and ANATOP.
With this driver, client can use generic regmap API to access registers
which are registered into syscon.

Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Dong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

3 files changed, 185 insertions, 0 deletions

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 856ec00ab787..909d84b1f5c1 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -1004,6 +1004,14 @@ config MFD_ANATOP
           MFD controller. This controller embeds regulator and
           thermal devices for Freescale i.MX platforms.
 
+config MFD_SYSCON
+        bool "System Controller Register R/W Based on Regmap"
+        depends on OF
+        select REGMAP_MMIO
+        help
+          Select this option to enable accessing system control registers
+          via regmap.
+
 config MFD_PALMAS
         bool "Support for the TI Palmas series chips"
         select MFD_CORE
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 2a4108d98442..07b66aff30b4 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -132,4 +132,5 @@ obj-$(CONFIG_MFD_PALMAS)	+= palmas.o
 obj-$(CONFIG_MFD_RC5T583)       += rc5t583.o rc5t583-irq.o
 obj-$(CONFIG_MFD_SEC_CORE)      += sec-core.o sec-irq.o
 obj-$(CONFIG_MFD_ANATOP)        += anatop-mfd.o
+obj-$(CONFIG_MFD_SYSCON)        += syscon.o
 obj-$(CONFIG_MFD_LM3533)        += lm3533-core.o lm3533-ctrlbank.o
diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
new file mode 100644
index 000000000000..65fe609026cc
--- /dev/null
+++ b/drivers/mfd/syscon.c
@@ -0,0 +1,176 @@
+/*
+ * System Control Driver
+ *
+ * Copyright (C) 2012 Freescale Semiconductor, Inc.
+ * Copyright (C) 2012 Linaro Ltd.
+ *
+ * Author: Dong Aisheng <dong.aisheng@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+static struct platform_driver syscon_driver;
+
+struct syscon {
+        struct device *dev;
+        void __iomem *base;
+        struct regmap *regmap;
+};
+
+static int syscon_match(struct device *dev, void *data)
+{
+        struct syscon *syscon = dev_get_drvdata(dev);
+        struct device_node *dn = data;
+
+        return (syscon->dev->of_node == dn) ? 1 : 0;
+}
+
+struct regmap *syscon_node_to_regmap(struct device_node *np)
+{
+        struct syscon *syscon;
+        struct device *dev;
+
+        dev = driver_find_device(&syscon_driver.driver, NULL, np,
+                                 syscon_match);
+        if (!dev)
+                return ERR_PTR(-EPROBE_DEFER);
+
+        syscon = dev_get_drvdata(dev);
+
+        return syscon->regmap;
+}
+EXPORT_SYMBOL_GPL(syscon_node_to_regmap);
+
+struct regmap *syscon_regmap_lookup_by_compatible(const char *s)
+{
+        struct device_node *syscon_np;
+        struct regmap *regmap;
+
+        syscon_np = of_find_compatible_node(NULL, NULL, s);
+        if (!syscon_np)
+                return ERR_PTR(-ENODEV);
+
+        regmap = syscon_node_to_regmap(syscon_np);
+        of_node_put(syscon_np);
+
+        return regmap;
+}
+EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_compatible);
+
+struct regmap *syscon_regmap_lookup_by_phandle(struct device_node *np,
+                                        const char *property)
+{
+        struct device_node *syscon_np;
+        struct regmap *regmap;
+
+        syscon_np = of_parse_phandle(np, property, 0);
+        if (!syscon_np)
+                return ERR_PTR(-ENODEV);
+
+        regmap = syscon_node_to_regmap(syscon_np);
+        of_node_put(syscon_np);
+
+        return regmap;
+}
+EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle);
+
+static const struct of_device_id of_syscon_match[] = {
+        { .compatible = "syscon", },
+        { },
+};
+
+static struct regmap_config syscon_regmap_config = {
+        .reg_bits = 32,
+        .val_bits = 32,
+        .reg_stride = 4,
+};
+
+static int __devinit syscon_probe(struct platform_device *pdev)
+{
+        struct device *dev = &pdev->dev;
+        struct device_node *np = dev->of_node;
+        struct syscon *syscon;
+        struct resource res;
+        int ret;
+
+        if (!np)
+                return -ENOENT;
+
+        syscon = devm_kzalloc(dev, sizeof(struct syscon),
+                            GFP_KERNEL);
+        if (!syscon)
+                return -ENOMEM;
+
+        syscon->base = of_iomap(np, 0);
+        if (!syscon->base)
+                return -EADDRNOTAVAIL;
+
+        ret = of_address_to_resource(np, 0, &res);
+        if (ret)
+                return ret;
+
+        syscon_regmap_config.max_register = res.end - res.start - 3;
+        syscon->regmap = devm_regmap_init_mmio(dev, syscon->base,
+                                        &syscon_regmap_config);
+        if (IS_ERR(syscon->regmap)) {
+                dev_err(dev, "regmap init failed\n");
+                return PTR_ERR(syscon->regmap);
+        }
+
+        syscon->dev = dev;
+        platform_set_drvdata(pdev, syscon);
+
+        dev_info(dev, "syscon regmap start 0x%x end 0x%x registered\n",
+                res.start, res.end);
+
+        return 0;
+}
+
+static int __devexit syscon_remove(struct platform_device *pdev)
+{
+        struct syscon *syscon;
+
+        syscon = platform_get_drvdata(pdev);
+        iounmap(syscon->base);
+        platform_set_drvdata(pdev, NULL);
+
+        return 0;
+}
+
+static struct platform_driver syscon_driver = {
+        .driver = {
+                .name = "syscon",
+                .owner = THIS_MODULE,
+                .of_match_table = of_syscon_match,
+        },
+        .probe          = syscon_probe,
+        .remove         = __devexit_p(syscon_remove),
+};
+
+static int __init syscon_init(void)
+{
+        return platform_driver_register(&syscon_driver);
+}
+postcore_initcall(syscon_init);
+
+static void __exit syscon_exit(void)
+{
+        platform_driver_unregister(&syscon_driver);
+}
+module_exit(syscon_exit);
+
+MODULE_AUTHOR("Dong Aisheng <dong.aisheng@linaro.org>");
+MODULE_DESCRIPTION("System Control driver");
+MODULE_LICENSE("GPL v2");