iio: adc: add exynos adc driver under iio framwork

This patch adds New driver to support:
1. Supports ADC IF found on EXYNOS4412/EXYNOS5250
   and future SoCs from Samsung
2. Add ADC driver under iio/adc framework
3. Also adds the Documentation for device tree bindings

Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

4 files changed, 500 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/arm/samsung/exynos-adc.txt b/Documentation/devicetree/bindings/arm/samsung/exynos-adc.txt
new file mode 100644
index 000000000000..f68637861b05
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/samsung/exynos-adc.txt
@@ -0,0 +1,52 @@
+Samsung Exynos Analog to Digital Converter bindings
+
+This devicetree binding are for the new adc driver written fori
+Exynos4 and upward SoCs from Samsung.
+
+New driver handles the following
+1. Supports ADC IF found on EXYNOS4412/EXYNOS5250
+   and future SoCs from Samsung
+2. Add ADC driver under iio/adc framework
+3. Also adds the Documentation for device tree bindings
+
+Required properties:
+- compatible:           Must be "samsung,exynos-adc-v1"
+                                for exynos4412/5250 controllers.
+                        Must be "samsung,exynos-adc-v2" for
+                                future controllers.
+- reg:                  Contains ADC register address range (base address and
+                        length).
+- interrupts:           Contains the interrupt information for the timer. The
+                        format is being dependent on which interrupt controller
+                        the Samsung device uses.
+- #io-channel-cells = <1>; As ADC has multiple outputs
+
+Note: child nodes can be added for auto probing from device tree.
+
+Example: adding device info in dtsi file
+
+adc: adc@12D10000 {
+        compatible = "samsung,exynos-adc-v1";
+        reg = <0x12D10000 0x100>;
+        interrupts = <0 106 0>;
+        #io-channel-cells = <1>;
+        io-channel-ranges;
+};
+
+
+Example: Adding child nodes in dts file
+
+adc@12D10000 {
+
+        /* NTC thermistor is a hwmon device */
+        ncp15wb473@0 {
+                compatible = "ntc,ncp15wb473";
+                pullup-uV = <1800000>;
+                pullup-ohm = <47000>;
+                pulldown-ohm = <0>;
+                io-channels = <&adc 4>;
+        };
+};
+
+Note: Does not apply to ADC driver under arch/arm/plat-samsung/
+Note: The child node can be added under the adc node or seperately.
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 00213eaf8aa9..a40d3c29f0cb 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -103,6 +103,13 @@ config AT91_ADC
         help
           Say yes here to build support for Atmel AT91 ADC.
 
+config EXYNOS_ADC
+        bool "Exynos ADC driver support"
+        help
+          Core support for the ADC block found in the Samsung EXYNOS series
+          of SoCs for drivers such as the touchscreen and hwmon to use to share
+          this resource.
+
 config LP8788_ADC
         bool "LP8788 ADC driver"
         depends on MFD_LP8788
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index ab910ba4664c..0a825bed43f6 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -11,6 +11,7 @@ obj-$(CONFIG_AD7791) += ad7791.o
 obj-$(CONFIG_AD7793) += ad7793.o
 obj-$(CONFIG_AD7887) += ad7887.o
 obj-$(CONFIG_AT91_ADC) += at91_adc.o
+obj-$(CONFIG_EXYNOS_ADC) += exynos_adc.o
 obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
 obj-$(CONFIG_MAX1363) += max1363.o
 obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
diff --git a/drivers/iio/adc/exynos_adc.c b/drivers/iio/adc/exynos_adc.c
new file mode 100644
index 000000000000..ed6fdd7e5212
--- /dev/null
+++ b/drivers/iio/adc/exynos_adc.c
@@ -0,0 +1,440 @@
+/*
+ *  exynos_adc.c - Support for ADC in EXYNOS SoCs
+ *
+ *  8 ~ 10 channel, 10/12-bit ADC
+ *
+ *  Copyright (C) 2013 Naveen Krishna Chatradhi <ch.naveen@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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/regulator/consumer.h>
+#include <linux/of_platform.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/machine.h>
+#include <linux/iio/driver.h>
+
+enum adc_version {
+        ADC_V1,
+        ADC_V2
+};
+
+/* EXYNOS4412/5250 ADC_V1 registers definitions */
+#define ADC_V1_CON(x)           ((x) + 0x00)
+#define ADC_V1_DLY(x)           ((x) + 0x08)
+#define ADC_V1_DATX(x)          ((x) + 0x0C)
+#define ADC_V1_INTCLR(x)        ((x) + 0x18)
+#define ADC_V1_MUX(x)           ((x) + 0x1c)
+
+/* Future ADC_V2 registers definitions */
+#define ADC_V2_CON1(x)          ((x) + 0x00)
+#define ADC_V2_CON2(x)          ((x) + 0x04)
+#define ADC_V2_STAT(x)          ((x) + 0x08)
+#define ADC_V2_INT_EN(x)        ((x) + 0x10)
+#define ADC_V2_INT_ST(x)        ((x) + 0x14)
+#define ADC_V2_VER(x)           ((x) + 0x20)
+
+/* Bit definitions for ADC_V1 */
+#define ADC_V1_CON_RES          (1u << 16)
+#define ADC_V1_CON_PRSCEN       (1u << 14)
+#define ADC_V1_CON_PRSCLV(x)    (((x) & 0xFF) << 6)
+#define ADC_V1_CON_STANDBY      (1u << 2)
+
+/* Bit definitions for ADC_V2 */
+#define ADC_V2_CON1_SOFT_RESET  (1u << 2)
+
+#define ADC_V2_CON2_OSEL        (1u << 10)
+#define ADC_V2_CON2_ESEL        (1u << 9)
+#define ADC_V2_CON2_HIGHF       (1u << 8)
+#define ADC_V2_CON2_C_TIME(x)   (((x) & 7) << 4)
+#define ADC_V2_CON2_ACH_SEL(x)  (((x) & 0xF) << 0)
+#define ADC_V2_CON2_ACH_MASK    0xF
+
+#define MAX_ADC_V2_CHANNELS     10
+#define MAX_ADC_V1_CHANNELS     8
+
+/* Bit definitions common for ADC_V1 and ADC_V2 */
+#define ADC_CON_EN_START        (1u << 0)
+#define ADC_DATX_MASK           0xFFF
+
+#define EXYNOS_ADC_TIMEOUT      (msecs_to_jiffies(1000))
+
+struct exynos_adc {
+        void __iomem            *regs;
+        struct clk              *clk;
+        unsigned int            irq;
+        struct regulator        *vdd;
+
+        struct completion       completion;
+
+        u32                     value;
+        unsigned int            version;
+};
+
+static const struct of_device_id exynos_adc_match[] = {
+        { .compatible = "samsung,exynos-adc-v1", .data = (void *)ADC_V1 },
+        { .compatible = "samsung,exynos-adc-v2", .data = (void *)ADC_V2 },
+        {},
+};
+MODULE_DEVICE_TABLE(of, exynos_adc_match);
+
+static inline unsigned int exynos_adc_get_version(struct platform_device *pdev)
+{
+        const struct of_device_id *match;
+
+        match = of_match_node(exynos_adc_match, pdev->dev.of_node);
+        return (unsigned int)match->data;
+}
+
+static int exynos_read_raw(struct iio_dev *indio_dev,
+                                struct iio_chan_spec const *chan,
+                                int *val,
+                                int *val2,
+                                long mask)
+{
+        struct exynos_adc *info = iio_priv(indio_dev);
+        unsigned long timeout;
+        u32 con1, con2;
+
+        if (mask != IIO_CHAN_INFO_RAW)
+                return -EINVAL;
+
+        mutex_lock(&indio_dev->mlock);
+
+        /* Select the channel to be used and Trigger conversion */
+        if (info->version == ADC_V2) {
+                con2 = readl(ADC_V2_CON2(info->regs));
+                con2 &= ~ADC_V2_CON2_ACH_MASK;
+                con2 |= ADC_V2_CON2_ACH_SEL(chan->address);
+                writel(con2, ADC_V2_CON2(info->regs));
+
+                con1 = readl(ADC_V2_CON1(info->regs));
+                writel(con1 | ADC_CON_EN_START,
+                                ADC_V2_CON1(info->regs));
+        } else {
+                writel(chan->address, ADC_V1_MUX(info->regs));
+
+                con1 = readl(ADC_V1_CON(info->regs));
+                writel(con1 | ADC_CON_EN_START,
+                                ADC_V1_CON(info->regs));
+        }
+
+        timeout = wait_for_completion_interruptible_timeout
+                        (&info->completion, EXYNOS_ADC_TIMEOUT);
+        *val = info->value;
+
+        mutex_unlock(&indio_dev->mlock);
+
+        if (timeout == 0)
+                return -ETIMEDOUT;
+
+        return IIO_VAL_INT;
+}
+
+static irqreturn_t exynos_adc_isr(int irq, void *dev_id)
+{
+        struct exynos_adc *info = (struct exynos_adc *)dev_id;
+
+        /* Read value */
+        info->value = readl(ADC_V1_DATX(info->regs)) &
+                                                ADC_DATX_MASK;
+        /* clear irq */
+        if (info->version == ADC_V2)
+                writel(1, ADC_V2_INT_ST(info->regs));
+        else
+                writel(1, ADC_V1_INTCLR(info->regs));
+
+        complete(&info->completion);
+
+        return IRQ_HANDLED;
+}
+
+static int exynos_adc_reg_access(struct iio_dev *indio_dev,
+                              unsigned reg, unsigned writeval,
+                              unsigned *readval)
+{
+        struct exynos_adc *info = iio_priv(indio_dev);
+
+        if (readval == NULL)
+                return -EINVAL;
+
+        *readval = readl(info->regs + reg);
+
+        return 0;
+}
+
+static const struct iio_info exynos_adc_iio_info = {
+        .read_raw = &exynos_read_raw,
+        .debugfs_reg_access = &exynos_adc_reg_access,
+        .driver_module = THIS_MODULE,
+};
+
+#define ADC_CHANNEL(_index, _id) {                      \
+        .type = IIO_VOLTAGE,                            \
+        .indexed = 1,                                   \
+        .channel = _index,                              \
+        .address = _index,                              \
+        .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT,    \
+        .datasheet_name = _id,                          \
+}
+
+static const struct iio_chan_spec exynos_adc_iio_channels[] = {
+        ADC_CHANNEL(0, "adc0"),
+        ADC_CHANNEL(1, "adc1"),
+        ADC_CHANNEL(2, "adc2"),
+        ADC_CHANNEL(3, "adc3"),
+        ADC_CHANNEL(4, "adc4"),
+        ADC_CHANNEL(5, "adc5"),
+        ADC_CHANNEL(6, "adc6"),
+        ADC_CHANNEL(7, "adc7"),
+        ADC_CHANNEL(8, "adc8"),
+        ADC_CHANNEL(9, "adc9"),
+};
+
+static int exynos_adc_remove_devices(struct device *dev, void *c)
+{
+        struct platform_device *pdev = to_platform_device(dev);
+
+        platform_device_unregister(pdev);
+
+        return 0;
+}
+
+static void exynos_adc_hw_init(struct exynos_adc *info)
+{
+        u32 con1, con2;
+
+        if (info->version == ADC_V2) {
+                con1 = ADC_V2_CON1_SOFT_RESET;
+                writel(con1, ADC_V2_CON1(info->regs));
+
+                con2 = ADC_V2_CON2_OSEL | ADC_V2_CON2_ESEL |
+                        ADC_V2_CON2_HIGHF | ADC_V2_CON2_C_TIME(0);
+                writel(con2, ADC_V2_CON2(info->regs));
+
+                /* Enable interrupts */
+                writel(1, ADC_V2_INT_EN(info->regs));
+        } else {
+                /* set default prescaler values and Enable prescaler */
+                con1 =  ADC_V1_CON_PRSCLV(49) | ADC_V1_CON_PRSCEN;
+
+                /* Enable 12-bit ADC resolution */
+                con1 |= ADC_V1_CON_RES;
+                writel(con1, ADC_V1_CON(info->regs));
+        }
+}
+
+static int exynos_adc_probe(struct platform_device *pdev)
+{
+        struct exynos_adc *info = NULL;
+        struct device_node *np = pdev->dev.of_node;
+        struct iio_dev *indio_dev = NULL;
+        struct resource *mem;
+        int ret = -ENODEV;
+        int irq;
+
+        if (!np)
+                return ret;
+
+        indio_dev = iio_device_alloc(sizeof(struct exynos_adc));
+        if (!indio_dev) {
+                dev_err(&pdev->dev, "failed allocating iio device\n");
+                return -ENOMEM;
+        }
+
+        info = iio_priv(indio_dev);
+
+        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+        info->regs = devm_request_and_ioremap(&pdev->dev, mem);
+        if (!info->regs) {
+                ret = -ENOMEM;
+                goto err_iio;
+        }
+
+        irq = platform_get_irq(pdev, 0);
+        if (irq < 0) {
+                dev_err(&pdev->dev, "no irq resource?\n");
+                ret = irq;
+                goto err_iio;
+        }
+
+        info->irq = irq;
+
+        init_completion(&info->completion);
+
+        ret = request_irq(info->irq, exynos_adc_isr,
+                                        0, dev_name(&pdev->dev), info);
+        if (ret < 0) {
+                dev_err(&pdev->dev, "failed requesting irq, irq = %d\n",
+                                                        info->irq);
+                goto err_iio;
+        }
+
+        info->clk = devm_clk_get(&pdev->dev, "adc");
+        if (IS_ERR(info->clk)) {
+                dev_err(&pdev->dev, "failed getting clock, err = %ld\n",
+                                                        PTR_ERR(info->clk));
+                ret = PTR_ERR(info->clk);
+                goto err_irq;
+        }
+
+        info->vdd = devm_regulator_get(&pdev->dev, "vdd");
+        if (IS_ERR(info->vdd)) {
+                dev_err(&pdev->dev, "failed getting regulator, err = %ld\n",
+                                                        PTR_ERR(info->vdd));
+                ret = PTR_ERR(info->vdd);
+                goto err_irq;
+        }
+
+        info->version = exynos_adc_get_version(pdev);
+
+        platform_set_drvdata(pdev, indio_dev);
+
+        indio_dev->name = dev_name(&pdev->dev);
+        indio_dev->dev.parent = &pdev->dev;
+        indio_dev->dev.of_node = pdev->dev.of_node;
+        indio_dev->info = &exynos_adc_iio_info;
+        indio_dev->modes = INDIO_DIRECT_MODE;
+        indio_dev->channels = exynos_adc_iio_channels;
+
+        if (info->version == ADC_V1)
+                indio_dev->num_channels = MAX_ADC_V1_CHANNELS;
+        else
+                indio_dev->num_channels = MAX_ADC_V2_CHANNELS;
+
+        ret = iio_device_register(indio_dev);
+        if (ret)
+                goto err_irq;
+
+        ret = regulator_enable(info->vdd);
+        if (ret)
+                goto err_iio_dev;
+
+        clk_prepare_enable(info->clk);
+
+        exynos_adc_hw_init(info);
+
+        ret = of_platform_populate(np, exynos_adc_match, NULL, &pdev->dev);
+        if (ret < 0) {
+                dev_err(&pdev->dev, "failed adding child nodes\n");
+                goto err_of_populate;
+        }
+
+        return 0;
+
+err_of_populate:
+        device_for_each_child(&pdev->dev, NULL,
+                                exynos_adc_remove_devices);
+        regulator_disable(info->vdd);
+        clk_disable_unprepare(info->clk);
+err_iio_dev:
+        iio_device_unregister(indio_dev);
+err_irq:
+        free_irq(info->irq, info);
+err_iio:
+        iio_device_free(indio_dev);
+        return ret;
+}
+
+static int exynos_adc_remove(struct platform_device *pdev)
+{
+        struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+        struct exynos_adc *info = iio_priv(indio_dev);
+
+        device_for_each_child(&pdev->dev, NULL,
+                                exynos_adc_remove_devices);
+        regulator_disable(info->vdd);
+        clk_disable_unprepare(info->clk);
+        iio_device_unregister(indio_dev);
+        free_irq(info->irq, info);
+        iio_device_free(indio_dev);
+
+        return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int exynos_adc_suspend(struct device *dev)
+{
+        struct platform_device *pdev = to_platform_device(dev);
+        struct exynos_adc *info = platform_get_drvdata(pdev);
+        u32 con;
+
+        if (info->version == ADC_V2) {
+                con = readl(ADC_V2_CON1(info->regs));
+                con &= ~ADC_CON_EN_START;
+                writel(con, ADC_V2_CON1(info->regs));
+        } else {
+                con = readl(ADC_V1_CON(info->regs));
+                con |= ADC_V1_CON_STANDBY;
+                writel(con, ADC_V1_CON(info->regs));
+        }
+
+        clk_disable_unprepare(info->clk);
+        regulator_disable(info->vdd);
+
+        return 0;
+}
+
+static int exynos_adc_resume(struct device *dev)
+{
+        struct platform_device *pdev = to_platform_device(dev);
+        struct exynos_adc *info = platform_get_drvdata(pdev);
+        int ret;
+
+        ret = regulator_enable(info->vdd);
+        if (ret)
+                return ret;
+
+        clk_prepare_enable(info->clk);
+
+        exynos_adc_hw_init(info);
+
+        return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(exynos_adc_pm_ops,
+                        exynos_adc_suspend,
+                        exynos_adc_resume);
+
+static struct platform_driver exynos_adc_driver = {
+        .probe          = exynos_adc_probe,
+        .remove         = exynos_adc_remove,
+        .driver         = {
+                .name   = "exynos-adc",
+                .owner  = THIS_MODULE,
+                .of_match_table = of_match_ptr(exynos_adc_match),
+                .pm     = &exynos_adc_pm_ops,
+        },
+};
+
+module_platform_driver(exynos_adc_driver);
+
+MODULE_AUTHOR("Naveen Krishna Chatradhi <ch.naveen@samsung.com>");
+MODULE_DESCRIPTION("Samsung EXYNOS5 ADC driver");
+MODULE_LICENSE("GPL v2");