regulator: add userspace-consumer driver

The userspace-consumer driver allows control of voltage and current
regulator state from userspace. This is required for fine-grained
power management of devices that are completely controller by userspace
applications, e.g. a GPS transciever connected to a serial port.

Signed-off-by: Mike Rapoport <mike@compulab.co.il>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

1 files changed, 200 insertions, 0 deletions

diff --git a/drivers/regulator/userspace-consumer.c b/drivers/regulator/userspace-consumer.c
new file mode 100644
index 000000000000..71fcf9df00f6
--- /dev/null
+++ b/drivers/regulator/userspace-consumer.c
@@ -0,0 +1,200 @@
+/*
+ * userspace-consumer.c
+ *
+ * Copyright 2009 CompuLab, Ltd.
+ *
+ * Author: Mike Rapoport <mike@compulab.co.il>
+ *
+ * Based of virtual consumer driver:
+ *   Copyright 2008 Wolfson Microelectronics PLC.
+ *   Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
+ *
+ * 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/mutex.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+#include <linux/regulator/userspace-consumer.h>
+
+struct userspace_consumer_data {
+        const char *name;
+
+        struct mutex lock;
+        bool enabled;
+
+        int num_supplies;
+        struct regulator_bulk_data *supplies;
+};
+
+static ssize_t show_name(struct device *dev,
+                          struct device_attribute *attr, char *buf)
+{
+        struct userspace_consumer_data *data = dev_get_drvdata(dev);
+
+        return sprintf(buf, "%s\n", data->name);
+}
+
+static ssize_t show_state(struct device *dev,
+                          struct device_attribute *attr, char *buf)
+{
+        struct userspace_consumer_data *data = dev_get_drvdata(dev);
+
+        if (data->enabled)
+                return sprintf(buf, "enabled\n");
+
+        return sprintf(buf, "disabled\n");
+}
+
+static ssize_t set_state(struct device *dev, struct device_attribute *attr,
+                         const char *buf, size_t count)
+{
+        struct userspace_consumer_data *data = dev_get_drvdata(dev);
+        bool enabled;
+        int ret;
+
+        /*
+         * sysfs_streq() doesn't need the \n's, but we add them so the strings
+         * will be shared with show_state(), above.
+         */
+        if (sysfs_streq(buf, "enabled\n") || sysfs_streq(buf, "1"))
+                enabled = true;
+        else if (sysfs_streq(buf, "disabled\n") || sysfs_streq(buf, "0"))
+                enabled = false;
+        else {
+                dev_err(dev, "Configuring invalid mode\n");
+                return count;
+        }
+
+        mutex_lock(&data->lock);
+        if (enabled != data->enabled) {
+                if (enabled)
+                        ret = regulator_bulk_enable(data->num_supplies,
+                                                    data->supplies);
+                else
+                        ret = regulator_bulk_disable(data->num_supplies,
+                                                     data->supplies);
+
+                if (ret == 0)
+                        data->enabled = enabled;
+                else
+                        dev_err(dev, "Failed to configure state: %d\n", ret);
+        }
+        mutex_unlock(&data->lock);
+
+        return count;
+}
+
+static DEVICE_ATTR(name, 0444, show_name, NULL);
+static DEVICE_ATTR(state, 0644, show_state, set_state);
+
+static struct device_attribute *attributes[] = {
+        &dev_attr_name,
+        &dev_attr_state,
+};
+
+static int regulator_userspace_consumer_probe(struct platform_device *pdev)
+{
+        struct regulator_userspace_consumer_data *pdata;
+        struct userspace_consumer_data *drvdata;
+        int ret, i;
+
+        pdata = pdev->dev.platform_data;
+        if (!pdata)
+                return -EINVAL;
+
+        drvdata = kzalloc(sizeof(struct userspace_consumer_data), GFP_KERNEL);
+        if (drvdata == NULL)
+                return -ENOMEM;
+
+        drvdata->name = pdata->name;
+        drvdata->num_supplies = pdata->num_supplies;
+        drvdata->supplies = pdata->supplies;
+
+        mutex_init(&drvdata->lock);
+
+        ret = regulator_bulk_get(&pdev->dev, drvdata->num_supplies,
+                                 drvdata->supplies);
+        if (ret) {
+                dev_err(&pdev->dev, "Failed to get supplies: %d\n", ret);
+                goto err_alloc_supplies;
+        }
+
+        for (i = 0; i < ARRAY_SIZE(attributes); i++) {
+                ret = device_create_file(&pdev->dev, attributes[i]);
+                if (ret != 0)
+                        goto err_create_attrs;
+        }
+
+        if (pdata->init_on)
+                ret = regulator_bulk_enable(drvdata->num_supplies,
+                                            drvdata->supplies);
+
+        drvdata->enabled = pdata->init_on;
+
+        if (ret) {
+                dev_err(&pdev->dev, "Failed to set initial state: %d\n", ret);
+                goto err_create_attrs;
+        }
+
+        platform_set_drvdata(pdev, drvdata);
+
+        return 0;
+
+err_create_attrs:
+        for (i = 0; i < ARRAY_SIZE(attributes); i++)
+                device_remove_file(&pdev->dev, attributes[i]);
+
+        regulator_bulk_free(drvdata->num_supplies, drvdata->supplies);
+
+err_alloc_supplies:
+        kfree(drvdata);
+        return ret;
+}
+
+static int regulator_userspace_consumer_remove(struct platform_device *pdev)
+{
+        struct userspace_consumer_data *data = platform_get_drvdata(pdev);
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(attributes); i++)
+                device_remove_file(&pdev->dev, attributes[i]);
+
+        if (data->enabled)
+                regulator_bulk_disable(data->num_supplies, data->supplies);
+
+        regulator_bulk_free(data->num_supplies, data->supplies);
+        kfree(data);
+
+        return 0;
+}
+
+static struct platform_driver regulator_userspace_consumer_driver = {
+        .probe          = regulator_userspace_consumer_probe,
+        .remove         = regulator_userspace_consumer_remove,
+        .driver         = {
+                .name           = "reg-userspace-consumer",
+        },
+};
+
+
+static int __init regulator_userspace_consumer_init(void)
+{
+        return platform_driver_register(&regulator_userspace_consumer_driver);
+}
+module_init(regulator_userspace_consumer_init);
+
+static void __exit regulator_userspace_consumer_exit(void)
+{
+        platform_driver_unregister(&regulator_userspace_consumer_driver);
+}
+module_exit(regulator_userspace_consumer_exit);
+
+MODULE_AUTHOR("Mike Rapoport <mike@compulab.co.il>");
+MODULE_DESCRIPTION("Userspace consumer for voltage and current regulators");
+MODULE_LICENSE("GPL");