regulator: new drivers for AD5398 and AD5821

The AD5398 and AD5821 are single 10-bit DAC with 120 mA output current
sink capability. They feature an internal reference and operates from
a single 2.7 V to 5.5 V supply.

This driver supports both the AD5398 and the AD5821.  It adapts into the
voltage and current framework.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

3 files changed, 295 insertions, 0 deletions

diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index 04f2e085116a..679ea3759449 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -201,5 +201,11 @@ config REGULATOR_88PM8607
         help
           This driver supports 88PM8607 voltage regulator chips.
 
+config REGULATOR_AD5398
+        tristate "Analog Devices AD5398/AD5821 regulators"
+        depends on I2C
+        help
+          This driver supports AD5398 and AD5821 current regulator chips.
+          If building into module, its name is ad5398.ko.
 endif
 
diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
index 4e7feece22d5..c256668300a6 100644
--- a/drivers/regulator/Makefile
+++ b/drivers/regulator/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_REGULATOR_FIXED_VOLTAGE) += fixed.o
 obj-$(CONFIG_REGULATOR_VIRTUAL_CONSUMER) += virtual.o
 obj-$(CONFIG_REGULATOR_USERSPACE_CONSUMER) += userspace-consumer.o
 
+obj-$(CONFIG_REGULATOR_AD5398) += ad5398.o
 obj-$(CONFIG_REGULATOR_BQ24022) += bq24022.o
 obj-$(CONFIG_REGULATOR_DUMMY) += dummy.o
 obj-$(CONFIG_REGULATOR_LP3971) += lp3971.o
diff --git a/drivers/regulator/ad5398.c b/drivers/regulator/ad5398.c
new file mode 100644
index 000000000000..6de6bdaeff7c
--- /dev/null
+++ b/drivers/regulator/ad5398.c
@@ -0,0 +1,288 @@
+/*
+ * Voltage and current regulation for AD5398 and AD5821
+ *
+ * Copyright 2010 Analog Devices Inc.
+ *
+ * Enter bugs at http://blackfin.uclinux.org/
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+
+#define AD5398_CURRENT_EN_MASK  0x8000
+
+struct ad5398_chip_info {
+        struct i2c_client *client;
+        int min_uA;
+        int max_uA;
+        unsigned int current_level;
+        unsigned int current_mask;
+        unsigned int current_offset;
+        struct regulator_dev rdev;
+};
+
+static int ad5398_calc_current(struct ad5398_chip_info *chip,
+        unsigned selector)
+{
+        unsigned range_uA = chip->max_uA - chip->min_uA;
+
+        return chip->min_uA + (selector * range_uA / chip->current_level);
+}
+
+static int ad5398_read_reg(struct i2c_client *client, unsigned short *data)
+{
+        unsigned short val;
+        int ret;
+
+        ret = i2c_master_recv(client, (char *)&val, 2);
+        if (ret < 0) {
+                dev_err(&client->dev, "I2C read error\n");
+                return ret;
+        }
+        *data = be16_to_cpu(val);
+
+        return ret;
+}
+
+static int ad5398_write_reg(struct i2c_client *client, const unsigned short data)
+{
+        unsigned short val;
+        int ret;
+
+        val = cpu_to_be16(data);
+        ret = i2c_master_send(client, (char *)&val, 2);
+        if (ret < 0)
+                dev_err(&client->dev, "I2C write error\n");
+
+        return ret;
+}
+
+static int ad5398_get_current_limit(struct regulator_dev *rdev)
+{
+        struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
+        struct i2c_client *client = chip->client;
+        unsigned short data;
+        int ret;
+
+        ret = ad5398_read_reg(client, &data);
+        if (ret < 0)
+                return ret;
+
+        ret = (data & chip->current_mask) >> chip->current_offset;
+
+        return ad5398_calc_current(chip, ret);
+}
+
+static int ad5398_set_current_limit(struct regulator_dev *rdev, int min_uA, int max_uA)
+{
+        struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
+        struct i2c_client *client = chip->client;
+        unsigned range_uA = chip->max_uA - chip->min_uA;
+        unsigned selector;
+        unsigned short data;
+        int ret;
+
+        if (min_uA > chip->max_uA || min_uA < chip->min_uA)
+                return -EINVAL;
+        if (max_uA > chip->max_uA || max_uA < chip->min_uA)
+                return -EINVAL;
+
+        selector = ((min_uA - chip->min_uA) * chip->current_level +
+                        range_uA - 1) / range_uA;
+        if (ad5398_calc_current(chip, selector) > max_uA)
+                return -EINVAL;
+
+        dev_dbg(&client->dev, "changing current %dmA\n",
+                ad5398_calc_current(chip, selector) / 1000);
+
+        /* read chip enable bit */
+        ret = ad5398_read_reg(client, &data);
+        if (ret < 0)
+                return ret;
+
+        /* prepare register data */
+        selector = (selector << chip->current_offset) & chip->current_mask;
+        data = (unsigned short)selector | (data & AD5398_CURRENT_EN_MASK);
+
+        /* write the new current value back as well as enable bit */
+        ret = ad5398_write_reg(client, data);
+
+        return ret;
+}
+
+static int ad5398_is_enabled(struct regulator_dev *rdev)
+{
+        struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
+        struct i2c_client *client = chip->client;
+        unsigned short data;
+        int ret;
+
+        ret = ad5398_read_reg(client, &data);
+        if (ret < 0)
+                return ret;
+
+        if (data & AD5398_CURRENT_EN_MASK)
+                return 1;
+        else
+                return 0;
+}
+
+static int ad5398_enable(struct regulator_dev *rdev)
+{
+        struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
+        struct i2c_client *client = chip->client;
+        unsigned short data;
+        int ret;
+
+        ret = ad5398_read_reg(client, &data);
+        if (ret < 0)
+                return ret;
+
+        if (data & AD5398_CURRENT_EN_MASK)
+                return 0;
+
+        data |= AD5398_CURRENT_EN_MASK;
+
+        ret = ad5398_write_reg(client, data);
+
+        return ret;
+}
+
+static int ad5398_disable(struct regulator_dev *rdev)
+{
+        struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
+        struct i2c_client *client = chip->client;
+        unsigned short data;
+        int ret;
+
+        ret = ad5398_read_reg(client, &data);
+        if (ret < 0)
+                return ret;
+
+        if (!(data & AD5398_CURRENT_EN_MASK))
+                return 0;
+
+        data &= ~AD5398_CURRENT_EN_MASK;
+
+        ret = ad5398_write_reg(client, data);
+
+        return ret;
+}
+
+static struct regulator_ops ad5398_ops = {
+        .get_current_limit = ad5398_get_current_limit,
+        .set_current_limit = ad5398_set_current_limit,
+        .enable = ad5398_enable,
+        .disable = ad5398_disable,
+        .is_enabled = ad5398_is_enabled,
+};
+
+static struct regulator_desc ad5398_reg = {
+        .name = "isink",
+        .id = 0,
+        .ops = &ad5398_ops,
+        .type = REGULATOR_CURRENT,
+        .owner = THIS_MODULE,
+};
+
+struct ad5398_current_data_format {
+        int current_bits;
+        int current_offset;
+        int min_uA;
+        int max_uA;
+};
+
+static const struct ad5398_current_data_format df_10_4_120 = {10, 4, 0, 120000};
+
+static const struct i2c_device_id ad5398_id[] = {
+        { "ad5398", (kernel_ulong_t)&df_10_4_120 },
+        { "ad5821", (kernel_ulong_t)&df_10_4_120 },
+        { }
+};
+MODULE_DEVICE_TABLE(i2c, ad5398_id);
+
+static int __devinit ad5398_probe(struct i2c_client *client,
+                                const struct i2c_device_id *id)
+{
+        struct regulator_dev *rdev;
+        struct regulator_init_data *init_data = client->dev.platform_data;
+        struct ad5398_chip_info *chip;
+        const struct ad5398_current_data_format *df =
+                        (struct ad5398_current_data_format *)id->driver_data;
+        int ret;
+
+        if (!init_data)
+                return -EINVAL;
+
+        chip = kzalloc(sizeof(*chip), GFP_KERNEL);
+        if (!chip)
+                return -ENOMEM;
+
+        chip->client = client;
+
+        chip->min_uA = df->min_uA;
+        chip->max_uA = df->max_uA;
+        chip->current_level = 1 << df->current_bits;
+        chip->current_offset = df->current_offset;
+        chip->current_mask = (chip->current_level - 1) << chip->current_offset;
+
+        rdev = regulator_register(&ad5398_reg, &client->dev, init_data, chip);
+        if (IS_ERR(rdev)) {
+                ret = PTR_ERR(rdev);
+                dev_err(&client->dev, "failed to register %s %s\n",
+                        id->name, ad5398_reg.name);
+                goto err;
+        }
+
+        i2c_set_clientdata(client, chip);
+        dev_dbg(&client->dev, "%s regulator driver is registered.\n", id->name);
+        return 0;
+
+err:
+        kfree(chip);
+        return ret;
+}
+
+static int __devexit ad5398_remove(struct i2c_client *client)
+{
+        struct ad5398_chip_info *chip = i2c_get_clientdata(client);
+
+        regulator_unregister(&chip->rdev);
+        kfree(chip);
+        i2c_set_clientdata(client, NULL);
+
+        return 0;
+}
+
+static struct i2c_driver ad5398_driver = {
+        .probe = ad5398_probe,
+        .remove = __devexit_p(ad5398_remove),
+        .driver         = {
+                .name   = "ad5398",
+        },
+        .id_table       = ad5398_id,
+};
+
+static int __init ad5398_init(void)
+{
+        return i2c_add_driver(&ad5398_driver);
+}
+module_init(ad5398_init);
+
+static void __exit ad5398_exit(void)
+{
+        i2c_del_driver(&ad5398_driver);
+}
+module_exit(ad5398_exit);
+
+MODULE_DESCRIPTION("AD5398 and AD5821 current regulator driver");
+MODULE_AUTHOR("Sonic Zhang");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("i2c:ad5398-regulator");