MAX8952 PMIC Driver Initial Release

MAX8952 PMIC is used to provide voltage output between 770mV - 1400mV
with DVS support. In this initial release, users can set voltages for
four DVS modes, RAMP delay values, and SYNC frequency.
Controlling FPWM/SYNC_MODE/Pull-Down/Ramp Modes and reading CHIP_ID
is not supported in this release.

If GPIO of EN is not valid in platform data, the driver assumes that it
is always-on. If GPIO of VID0 or VID1 is invalid, the driver pulls down
VID0 and VID1 to fix DVS mode as 0 and disables DVS support.

We assume that V_OUT is capable to provide every voltage from 770mV to
1.40V in 10mV steps although the data sheet has some ambiguity on it.

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
--
v2:
	- Style correction
	- Can accept platform_data with invalid GPIOs
	- Removed unnecessary features
	- Improved error handling
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

1 files changed, 360 insertions, 0 deletions

diff --git a/drivers/regulator/max8952.c b/drivers/regulator/max8952.c
new file mode 100644
index 000000000000..f2af0b1c3925
--- /dev/null
+++ b/drivers/regulator/max8952.c
@@ -0,0 +1,360 @@
+/*
+ * max8952.c - Voltage and current regulation for the Maxim 8952
+ *
+ * Copyright (C) 2010 Samsung Electronics
+ * MyungJoo Ham <myungjoo.ham@samsung.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.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/err.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/max8952.h>
+#include <linux/mutex.h>
+#include <linux/gpio.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+
+/* Registers */
+enum {
+        MAX8952_REG_MODE0,
+        MAX8952_REG_MODE1,
+        MAX8952_REG_MODE2,
+        MAX8952_REG_MODE3,
+        MAX8952_REG_CONTROL,
+        MAX8952_REG_SYNC,
+        MAX8952_REG_RAMP,
+        MAX8952_REG_CHIP_ID1,
+        MAX8952_REG_CHIP_ID2,
+};
+
+struct max8952_data {
+        struct i2c_client       *client;
+        struct device           *dev;
+        struct mutex            mutex;
+        struct max8952_platform_data *pdata;
+        struct regulator_dev    *rdev;
+
+        bool vid0;
+        bool vid1;
+        bool en;
+};
+
+static int max8952_read_reg(struct max8952_data *max8952, u8 reg)
+{
+        int ret = i2c_smbus_read_byte_data(max8952->client, reg);
+        if (ret > 0)
+                ret &= 0xff;
+
+        return ret;
+}
+
+static int max8952_write_reg(struct max8952_data *max8952,
+                u8 reg, u8 value)
+{
+        return i2c_smbus_write_byte_data(max8952->client, reg, value);
+}
+
+static int max8952_voltage(struct max8952_data *max8952, u8 mode)
+{
+        return (max8952->pdata->dvs_mode[mode] * 10 + 770) * 1000;
+}
+
+static int max8952_list_voltage(struct regulator_dev *rdev,
+                unsigned int selector)
+{
+        struct max8952_data *max8952 = rdev_get_drvdata(rdev);
+
+        if (rdev_get_id(rdev) != 0)
+                return -EINVAL;
+
+        return max8952_voltage(max8952, selector);
+}
+
+static int max8952_is_enabled(struct regulator_dev *rdev)
+{
+        struct max8952_data *max8952 = rdev_get_drvdata(rdev);
+        return max8952->en;
+}
+
+static int max8952_enable(struct regulator_dev *rdev)
+{
+        struct max8952_data *max8952 = rdev_get_drvdata(rdev);
+
+        /* If not valid, assume "ALWAYS_HIGH" */
+        if (gpio_is_valid(max8952->pdata->gpio_en))
+                gpio_set_value(max8952->pdata->gpio_en, 1);
+
+        max8952->en = true;
+        return 0;
+}
+
+static int max8952_disable(struct regulator_dev *rdev)
+{
+        struct max8952_data *max8952 = rdev_get_drvdata(rdev);
+
+        /* If not valid, assume "ALWAYS_HIGH" -> not permitted */
+        if (gpio_is_valid(max8952->pdata->gpio_en))
+                gpio_set_value(max8952->pdata->gpio_en, 0);
+        else
+                return -EPERM;
+
+        max8952->en = false;
+        return 0;
+}
+
+static int max8952_get_voltage(struct regulator_dev *rdev)
+{
+        struct max8952_data *max8952 = rdev_get_drvdata(rdev);
+        u8 vid = 0;
+
+        if (max8952->vid0)
+                vid += 1;
+        if (max8952->vid1)
+                vid += 2;
+
+        return max8952_voltage(max8952, vid);
+}
+
+static int max8952_set_voltage(struct regulator_dev *rdev,
+                                int min_uV, int max_uV)
+{
+        struct max8952_data *max8952 = rdev_get_drvdata(rdev);
+        u8 vid = -1, i;
+
+        if (!gpio_is_valid(max8952->pdata->gpio_vid0) ||
+                        !gpio_is_valid(max8952->pdata->gpio_vid0)) {
+                /* DVS not supported */
+                return -EPERM;
+        }
+
+        for (i = 0; i < MAX8952_NUM_DVS_MODE; i++) {
+                int volt = max8952_voltage(max8952, i);
+
+                /* Set the voltage as low as possible within the range */
+                if (volt <= max_uV && volt >= min_uV)
+                        if (vid == -1 || max8952_voltage(max8952, vid) > volt)
+                                vid = i;
+        }
+
+        if (vid >= 0 && vid < MAX8952_NUM_DVS_MODE) {
+                max8952->vid0 = (vid % 2 == 1);
+                max8952->vid1 = (((vid >> 1) % 2) == 1);
+                gpio_set_value(max8952->pdata->gpio_vid0, max8952->vid0);
+                gpio_set_value(max8952->pdata->gpio_vid1, max8952->vid1);
+        } else
+                return -EINVAL;
+
+        return 0;
+}
+
+static struct regulator_ops max8952_ops = {
+        .list_voltage           = max8952_list_voltage,
+        .is_enabled             = max8952_is_enabled,
+        .enable                 = max8952_enable,
+        .disable                = max8952_disable,
+        .get_voltage            = max8952_get_voltage,
+        .set_voltage            = max8952_set_voltage,
+        .set_suspend_disable    = max8952_disable,
+};
+
+static struct regulator_desc regulator = {
+        .name           = "MAX8952_VOUT",
+        .id             = 0,
+        .n_voltages     = MAX8952_NUM_DVS_MODE,
+        .ops            = &max8952_ops,
+        .type           = REGULATOR_VOLTAGE,
+        .owner          = THIS_MODULE,
+};
+
+static int __devinit max8952_pmic_probe(struct i2c_client *client,
+                const struct i2c_device_id *i2c_id)
+{
+        struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
+        struct max8952_platform_data *pdata = client->dev.platform_data;
+        struct max8952_data *max8952;
+
+        int ret = 0, err = 0;
+
+        if (!pdata) {
+                dev_err(&client->dev, "Require the platform data\n");
+                return -EINVAL;
+        }
+
+        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE))
+                return -EIO;
+
+        max8952 = kzalloc(sizeof(struct max8952_data), GFP_KERNEL);
+        if (!max8952)
+                return -ENOMEM;
+
+        max8952->client = client;
+        max8952->dev = &client->dev;
+        max8952->pdata = pdata;
+        mutex_init(&max8952->mutex);
+
+        max8952->rdev = regulator_register(&regulator, max8952->dev,
+                        &pdata->reg_data, max8952);
+
+        ret = IS_ERR(max8952->rdev);
+        if (ret)
+                dev_err(max8952->dev, "regulator init failed (%d)\n", ret);
+
+        max8952->en = !!(pdata->reg_data.constraints.boot_on);
+        max8952->vid0 = (pdata->default_mode % 2) == 1;
+        max8952->vid1 = ((pdata->default_mode >> 1) % 2) == 1;
+
+        if (gpio_is_valid(pdata->gpio_en)) {
+                if (!gpio_request(pdata->gpio_en, "MAX8952 EN"))
+                        gpio_direction_output(pdata->gpio_en, max8952->en);
+                else
+                        err = 1;
+        } else
+                err = 2;
+
+        if (err) {
+                dev_info(max8952->dev, "EN gpio invalid: assume that EN"
+                                "is always High\n");
+                max8952->en = 1;
+                pdata->gpio_en = -1; /* Mark invalid */
+        }
+
+        err = 0;
+
+        if (gpio_is_valid(pdata->gpio_vid0) &&
+                        gpio_is_valid(pdata->gpio_vid1)) {
+                if (!gpio_request(pdata->gpio_vid0, "MAX8952 VID0"))
+                        gpio_direction_output(pdata->gpio_vid0,
+                                        (pdata->default_mode) % 2);
+                else
+                        err = 1;
+
+                if (!gpio_request(pdata->gpio_vid1, "MAX8952 VID1"))
+                        gpio_direction_output(pdata->gpio_vid1,
+                                (pdata->default_mode >> 1) % 2);
+                else {
+                        if (!err)
+                                gpio_free(pdata->gpio_vid0);
+                        err = 2;
+                }
+
+        } else
+                err = 3;
+
+        if (err) {
+                dev_warn(max8952->dev, "VID0/1 gpio invalid: "
+                                "DVS not avilable.\n");
+                max8952->vid0 = 0;
+                max8952->vid1 = 0;
+                /* Mark invalid */
+                pdata->gpio_vid0 = -1;
+                pdata->gpio_vid1 = -1;
+
+                /* Disable Pulldown of EN only */
+                max8952_write_reg(max8952, MAX8952_REG_CONTROL, 0x60);
+
+                dev_err(max8952->dev, "DVS modes disabled because VID0 and VID1"
+                                " do not have proper controls.\n");
+        } else {
+                /*
+                 * Disable Pulldown on EN, VID0, VID1 to reduce
+                 * leakage current of MAX8952 assuming that MAX8952
+                 * is turned on (EN==1). Note that without having VID0/1
+                 * properly connected, turning pulldown off can be
+                 * problematic. Thus, turn this off only when they are
+                 * controllable by GPIO.
+                 */
+                max8952_write_reg(max8952, MAX8952_REG_CONTROL, 0x0);
+        }
+
+        max8952_write_reg(max8952, MAX8952_REG_MODE0,
+                        (max8952_read_reg(max8952,
+                                          MAX8952_REG_MODE0) & 0xC0) |
+                        (pdata->dvs_mode[0] & 0x3F));
+        max8952_write_reg(max8952, MAX8952_REG_MODE1,
+                        (max8952_read_reg(max8952,
+                                          MAX8952_REG_MODE1) & 0xC0) |
+                        (pdata->dvs_mode[1] & 0x3F));
+        max8952_write_reg(max8952, MAX8952_REG_MODE2,
+                        (max8952_read_reg(max8952,
+                                          MAX8952_REG_MODE2) & 0xC0) |
+                        (pdata->dvs_mode[2] & 0x3F));
+        max8952_write_reg(max8952, MAX8952_REG_MODE3,
+                        (max8952_read_reg(max8952,
+                                          MAX8952_REG_MODE3) & 0xC0) |
+                        (pdata->dvs_mode[3] & 0x3F));
+
+        max8952_write_reg(max8952, MAX8952_REG_SYNC,
+                        (max8952_read_reg(max8952, MAX8952_REG_SYNC) & 0x3F) |
+                        ((pdata->sync_freq & 0x3) << 6));
+        max8952_write_reg(max8952, MAX8952_REG_RAMP,
+                        (max8952_read_reg(max8952, MAX8952_REG_RAMP) & 0x1F) |
+                        ((pdata->ramp_speed & 0x7) << 5));
+
+        i2c_set_clientdata(client, max8952);
+
+        return ret;
+}
+
+static int __devexit max8952_pmic_remove(struct i2c_client *client)
+{
+        struct max8952_data *max8952 = i2c_get_clientdata(client);
+        struct max8952_platform_data *pdata = max8952->pdata;
+        struct regulator_dev *rdev = max8952->rdev;
+
+        regulator_unregister(rdev);
+
+        gpio_free(pdata->gpio_vid0);
+        gpio_free(pdata->gpio_vid1);
+        gpio_free(pdata->gpio_en);
+
+        kfree(max8952);
+        return 0;
+}
+
+static const struct i2c_device_id max8952_ids[] = {
+        { "max8952", 0 },
+        { },
+};
+MODULE_DEVICE_TABLE(i2c, max8952_ids);
+
+static struct i2c_driver max8952_pmic_driver = {
+        .probe          = max8952_pmic_probe,
+        .remove         = __devexit_p(max8952_pmic_remove),
+        .driver         = {
+                .name   = "max8952",
+        },
+        .id_table       = max8952_ids,
+};
+
+static int __init max8952_pmic_init(void)
+{
+        return i2c_add_driver(&max8952_pmic_driver);
+}
+subsys_initcall(max8952_pmic_init);
+
+static void __exit max8952_pmic_exit(void)
+{
+        i2c_del_driver(&max8952_pmic_driver);
+}
+module_exit(max8952_pmic_exit);
+
+MODULE_DESCRIPTION("MAXIM 8952 voltage regulator driver");
+MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
+MODULE_LICENSE("GPL");