[PATCH v6 1/2] iio: adc: add driver for Rockchip saradc

[Heiko Stübner]

The ADC is a 3-channel signal-ended 10-bit Successive Approximation
Register (SAR) A/D Converter. It uses the supply and ground as its reference
and converts the analog input signal into 10-bit binary digital codes.

Signed-off-by: Heiko Stuebner <***@sntech.de>
Reviewed-by: Hartmut Knaack <***@gmx.de>
---
changes since v5:
- address comments from Lars-Peter Clausen:
- reinit_completion
- use devm_ioremap_resource
- init_completion before requesting irq
- set clock statically. As pointed out, this is not really a property
of the board, but at most a user setting. But we'll simply wait for
a user of this to come along and set the clock statically for now.
changes since v4:
- address comments from Hartmut Knaack
- explain the DLY_PU_SOC value
- determine regulator voltage in IIO_CHAN_INFO_SCALE
- return ENODEV directly in the !np case
changes since v3:
- address comments from Jonathan Cameron
- explicitly check for negative values in error checks
- change Kconfig depends to ARCH_ROCKCHIP || (ARM && COMPILE_TEST)
to prevent issues due to undefined writel_relaxed functions
The previous check for OF was unecessary, as the only used function
is of_property_read_u32, for which a stub is defined for the !OF case.
changes since v2:
- address more comments from Peter Meerwald
mainly the missing info_mask_shared_by_type element
changes since v1:
- address comments from Peter Meerwald

drivers/iio/adc/Kconfig | 10 ++
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/rockchip_saradc.c | 317 ++++++++++++++++++++++++++++++++++++++
3 files changed, 328 insertions(+)
create mode 100644 drivers/iio/adc/rockchip_saradc.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index a80d236..01c6ed6 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -187,6 +187,16 @@ config NAU7802
To compile this driver as a module, choose M here: the
module will be called nau7802.

+config ROCKCHIP_SARADC
+ tristate "Rockchip SARADC driver"
+ depends on ARCH_ROCKCHIP || (ARM && COMPILE_TEST)
+ help
+ Say yes here to build support for the SARADC found in SoCs from
+ Rockchip.
+
+ To compile this driver as a module, choose M here: the
+ module will be called rockchip_saradc.
+
config TI_ADC081C
tristate "Texas Instruments ADC081C021/027"
depends on I2C
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 9d60f2d..8e2932d 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_MCP320X) += mcp320x.o
obj-$(CONFIG_MCP3422) += mcp3422.o
obj-$(CONFIG_MEN_Z188_ADC) += men_z188_adc.o
obj-$(CONFIG_NAU7802) += nau7802.o
+obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o
obj-$(CONFIG_TWL4030_MADC) += twl4030-madc.o
diff --git a/drivers/iio/adc/rockchip_saradc.c b/drivers/iio/adc/rockchip_saradc.c
new file mode 100644
index 0000000..1fad964
--- /dev/null
+++ b/drivers/iio/adc/rockchip_saradc.c
@@ -0,0 +1,317 @@
+/*
+ * Rockchip Successive Approximation Register (SAR) A/D Converter
+ * Copyright (C) 2014 ROCKCHIP, Inc.
+ *
+ * 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.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/regulator/consumer.h>
+#include <linux/iio/iio.h>
+
+#define SARADC_DATA 0x00
+#define SARADC_DATA_MASK 0x3ff
+
+#define SARADC_STAS 0x04
+#define SARADC_STAS_BUSY BIT(0)
+
+#define SARADC_CTRL 0x08
+#define SARADC_CTRL_IRQ_STATUS BIT(6)
+#define SARADC_CTRL_IRQ_ENABLE BIT(5)
+#define SARADC_CTRL_POWER_CTRL BIT(3)
+#define SARADC_CTRL_CHN_MASK 0x7
+
+#define SARADC_DLY_PU_SOC 0x0c
+#define SARADC_DLY_PU_SOC_MASK 0x3f
+
+#define SARADC_BITS 10
+#define SARADC_TIMEOUT msecs_to_jiffies(100)
+
+struct rockchip_saradc {
+ void __iomem *regs;
+ struct clk *pclk;
+ struct clk *clk;
+ struct completion completion;
+ struct regulator *vref;
+ u16 last_val;
+};
+
+static int rockchip_saradc_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long mask)
+{
+ struct rockchip_saradc *info = iio_priv(indio_dev);
+ int ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ mutex_lock(&indio_dev->mlock);
+
+ reinit_completion(&info->completion);
+
+ /* 8 clock periods as delay between power up and start cmd */
+ writel_relaxed(8, info->regs + SARADC_DLY_PU_SOC);
+
+ /* Select the channel to be used and trigger conversion */
+ writel(SARADC_CTRL_POWER_CTRL
+ | (chan->channel & SARADC_CTRL_CHN_MASK)
+ | SARADC_CTRL_IRQ_ENABLE,
+ info->regs + SARADC_CTRL);
+
+ if (!wait_for_completion_timeout(&info->completion,
+ SARADC_TIMEOUT)) {
+ writel_relaxed(0, info->regs + SARADC_CTRL);
+ mutex_unlock(&indio_dev->mlock);
+ return -ETIMEDOUT;
+ }
+
+ *val = info->last_val;
+ mutex_unlock(&indio_dev->mlock);
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_SCALE:
+ ret = regulator_get_voltage(info->vref);
+ if (ret < 0) {
+ dev_err(&indio_dev->dev, "failed to get voltage\n");
+ return ret;
+ }
+
+ *val = ret / 1000;
+ *val2 = SARADC_BITS;
+ return IIO_VAL_FRACTIONAL_LOG2;
+ default:
+ return -EINVAL;
+ }
+}
+
+static irqreturn_t rockchip_saradc_isr(int irq, void *dev_id)
+{
+ struct rockchip_saradc *info = (struct rockchip_saradc *)dev_id;
+
+ /* Read value */
+ info->last_val = readl_relaxed(info->regs + SARADC_DATA);
+ info->last_val &= SARADC_DATA_MASK;
+
+ /* Clear irq & power down adc */
+ writel_relaxed(0, info->regs + SARADC_CTRL);
+
+ complete(&info->completion);
+
+ return IRQ_HANDLED;
+}
+
+static const struct iio_info rockchip_saradc_iio_info = {
+ .read_raw = rockchip_saradc_read_raw,
+ .driver_module = THIS_MODULE,
+};
+
+#define ADC_CHANNEL(_index, _id) { \
+ .type = IIO_VOLTAGE, \
+ .indexed = 1, \
+ .channel = _index, \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+ .datasheet_name = _id, \
+}
+
+static const struct iio_chan_spec rockchip_saradc_iio_channels[] = {
+ ADC_CHANNEL(0, "adc0"),
+ ADC_CHANNEL(1, "adc1"),
+ ADC_CHANNEL(2, "adc2"),
+};
+
+static int rockchip_saradc_probe(struct platform_device *pdev)
+{
+ struct rockchip_saradc *info = NULL;
+ struct device_node *np = pdev->dev.of_node;
+ struct iio_dev *indio_dev = NULL;
+ struct resource *mem;
+ int ret;
+ int irq;
+ u32 rate;
+
+ if (!np)
+ return -ENODEV;
+
+ indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*info));
+ 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_ioremap_resource(&pdev->dev, mem);
+ if (IS_ERR(info->regs))
+ return PTR_ERR(info->regs);
+
+ init_completion(&info->completion);
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0) {
+ dev_err(&pdev->dev, "no irq resource?\n");
+ return irq;
+ }
+
+ ret = devm_request_irq(&pdev->dev, irq, rockchip_saradc_isr,
+ 0, dev_name(&pdev->dev), info);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed requesting irq %d\n", irq);
+ return ret;
+ }
+
+ info->pclk = devm_clk_get(&pdev->dev, "apb_pclk");
+ if (IS_ERR(info->pclk)) {
+ dev_err(&pdev->dev, "failed to get pclk\n");
+ return PTR_ERR(info->pclk);
+ }
+
+ info->clk = devm_clk_get(&pdev->dev, "saradc");
+ if (IS_ERR(info->clk)) {
+ dev_err(&pdev->dev, "failed to get adc clock\n");
+ return PTR_ERR(info->clk);
+ }
+
+ info->vref = devm_regulator_get(&pdev->dev, "vref");
+ if (IS_ERR(info->vref)) {
+ dev_err(&pdev->dev, "failed to get regulator, %ld\n",
+ PTR_ERR(info->vref));
+ return PTR_ERR(info->vref);
+ }
+
+ /*
+ * Use a default of 1MHz for the converter clock.
+ * This may become user-configurable in the future.
+ */
+ ret = clk_set_rate(info->clk, 1000000);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to set adc clk rate, %d\n", ret);
+ return ret;
+ }
+
+ ret = regulator_enable(info->vref);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to enable vref regulator\n");
+ return ret;
+ }
+
+ ret = clk_prepare_enable(info->pclk);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to enable pclk\n");
+ goto err_reg_voltage;
+ }
+
+ ret = clk_prepare_enable(info->clk);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to enable converter clock\n");
+ goto err_pclk;
+ }
+
+ 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 = &rockchip_saradc_iio_info;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+
+ indio_dev->channels = rockchip_saradc_iio_channels;
+ indio_dev->num_channels = ARRAY_SIZE(rockchip_saradc_iio_channels);
+
+ ret = iio_device_register(indio_dev);
+ if (ret)
+ goto err_clk;
+
+ return 0;
+
+err_clk:
+ clk_disable_unprepare(info->clk);
+err_pclk:
+ clk_disable_unprepare(info->pclk);
+err_reg_voltage:
+ regulator_disable(info->vref);
+ return ret;
+}
+
+static int rockchip_saradc_remove(struct platform_device *pdev)
+{
+ struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+ struct rockchip_saradc *info = iio_priv(indio_dev);
+
+ iio_device_unregister(indio_dev);
+ clk_disable_unprepare(info->clk);
+ clk_disable_unprepare(info->pclk);
+ regulator_disable(info->vref);
+
+ return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int rockchip_saradc_suspend(struct device *dev)
+{
+ struct iio_dev *indio_dev = dev_get_drvdata(dev);
+ struct rockchip_saradc *info = iio_priv(indio_dev);
+
+ clk_disable_unprepare(info->clk);
+ clk_disable_unprepare(info->pclk);
+ regulator_disable(info->vref);
+
+ return 0;
+}
+
+static int rockchip_saradc_resume(struct device *dev)
+{
+ struct iio_dev *indio_dev = dev_get_drvdata(dev);
+ struct rockchip_saradc *info = iio_priv(indio_dev);
+ int ret;
+
+ ret = regulator_enable(info->vref);
+ if (ret)
+ return ret;
+
+ ret = clk_prepare_enable(info->pclk);
+ if (ret)
+ return ret;
+
+ ret = clk_prepare_enable(info->clk);
+ if (ret)
+ return ret;
+
+ return ret;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(rockchip_saradc_pm_ops,
+ rockchip_saradc_suspend, rockchip_saradc_resume);
+
+static const struct of_device_id rockchip_saradc_match[] = {
+ { .compatible = "rockchip,saradc" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, rockchip_saradc_match);
+
+static struct platform_driver rockchip_saradc_driver = {
+ .probe = rockchip_saradc_probe,
+ .remove = rockchip_saradc_remove,
+ .driver = {
+ .name = "rockchip-saradc",
+ .owner = THIS_MODULE,
+ .of_match_table = rockchip_saradc_match,
+ .pm = &rockchip_saradc_pm_ops,
+ },
+};
+
+module_platform_driver(rockchip_saradc_driver);

[Heiko Stübner]

This add the necessary binding documentation for the saradc found in all recent
processors from Rockchip.

Signed-off-by: Heiko Stuebner <***@sntech.de>
---
changes since v5:
- remove clock-frquency property as described in patch 1/2

.../bindings/iio/adc/rockchip-saradc.txt | 24 ++++++++++++++++++++++
1 file changed, 24 insertions(+)
create mode 100644 Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt

diff --git a/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt b/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
new file mode 100644
index 0000000..5d3ec1d
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
@@ -0,0 +1,24 @@
+Rockchip Successive Approximation Register (SAR) A/D Converter bindings
+
+Required properties:
+- compatible: Should be "rockchip,saradc"
+- reg: physical base address of the controller and length of memory mapped
+ region.
+- interrupts: The interrupt number to the cpu. The interrupt specifier format
+ depends on the interrupt controller.
+- clocks: Must contain an entry for each entry in clock-names.
+- clock-names: Shall be "saradc" for the converter-clock, and "apb_pclk" for
+ the peripheral clock.
+- vref-supply: The regulator supply ADC reference voltage.
+- #io-channel-cells: Should be 1, see ../iio-bindings.txt
+
+Example:
+ saradc: ***@2006c000 {
+ compatible = "rockchip,saradc";
+ reg = <0x2006c000 0x100>;
+ interrupts = <GIC_SPI 26 IRQ_TYPE_LEVEL_HIGH>;
+ clocks = <&cru SCLK_SARADC>, <&cru PCLK_SARADC>;
+ clock-names = "saradc", "apb_pclk";
+ #io-channel-cells = <1>;
+ vref-supply = <&vcc18>;
+ };

[Jonathan Cameron]

Post by Heiko Stübner
This add the necessary binding documentation for the saradc found in all recent
processors from Rockchip.

Applied to the togreg branch of iio.git.
I have exercised a small amount of discretion wrt to the standard 3 weeks
as there really is very little different in here from previous versions
and no one has raised any comments on them.

It's nearly 3 weeks anyway!

J

Post by Heiko Stübner
---
- remove clock-frquency property as described in patch 1/2
.../bindings/iio/adc/rockchip-saradc.txt | 24 ++++++++++++++++++++++
1 file changed, 24 insertions(+)
create mode 100644 Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
diff --git a/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt b/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
new file mode 100644
index 0000000..5d3ec1d
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
@@ -0,0 +1,24 @@
+Rockchip Successive Approximation Register (SAR) A/D Converter bindings
+
+- compatible: Should be "rockchip,saradc"
+- reg: physical base address of the controller and length of memory mapped
+ region.
+- interrupts: The interrupt number to the cpu. The interrupt specifier format
+ depends on the interrupt controller.
+- clocks: Must contain an entry for each entry in clock-names.
+- clock-names: Shall be "saradc" for the converter-clock, and "apb_pclk" for
+ the peripheral clock.
+- vref-supply: The regulator supply ADC reference voltage.
+- #io-channel-cells: Should be 1, see ../iio-bindings.txt
+
+ compatible = "rockchip,saradc";
+ reg = <0x2006c000 0x100>;
+ interrupts = <GIC_SPI 26 IRQ_TYPE_LEVEL_HIGH>;
+ clocks = <&cru SCLK_SARADC>, <&cru PCLK_SARADC>;
+ clock-names = "saradc", "apb_pclk";
+ #io-channel-cells = <1>;
+ vref-supply = <&vcc18>;
+ };

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[Heiko Stübner]

Post by Jonathan Cameron

Post by Heiko Stübner
This add the necessary binding documentation for the saradc found in all
recent processors from Rockchip.

Applied to the togreg branch of iio.git.
I have exercised a small amount of discretion wrt to the standard 3 weeks
as there really is very little different in here from previous versions
and no one has raised any comments on them.

Did the binding patch make it into any tree? Because when I grep for saradc in
either linux-next or the iio tree I only get patch 1/2 (the driver itself) but
the binding document is somehow missing.


Thanks
Heiko

Post by Jonathan Cameron
It's nearly 3 weeks anyway!
J

Post by Heiko Stübner
---
- remove clock-frquency property as described in patch 1/2
.../bindings/iio/adc/rockchip-saradc.txt | 24
++++++++++++++++++++++ 1 file changed, 24 insertions(+)
create mode 100644
Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt>
diff --git a/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
b/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt new file
mode 100644
index 0000000..5d3ec1d
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
@@ -0,0 +1,24 @@
+Rockchip Successive Approximation Register (SAR) A/D Converter bindings
+
+- compatible: Should be "rockchip,saradc"
+- reg: physical base address of the controller and length of memory mapped
+ region.
+- interrupts: The interrupt number to the cpu. The interrupt specifier
format + depends on the interrupt controller.
+- clocks: Must contain an entry for each entry in clock-names.
+- clock-names: Shall be "saradc" for the converter-clock, and "apb_pclk"
for + the peripheral clock.
+- vref-supply: The regulator supply ADC reference voltage.
+- #io-channel-cells: Should be 1, see ../iio-bindings.txt
+
+ compatible = "rockchip,saradc";
+ reg = <0x2006c000 0x100>;
+ interrupts = <GIC_SPI 26 IRQ_TYPE_LEVEL_HIGH>;
+ clocks = <&cru SCLK_SARADC>, <&cru PCLK_SARADC>;
+ clock-names = "saradc", "apb_pclk";
+ #io-channel-cells = <1>;
+ vref-supply = <&vcc18>;
+ };

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[Jonathan Cameron]

Post by Heiko Stübner

Post by Jonathan Cameron

Post by Heiko Stübner
This add the necessary binding documentation for the saradc found in all
recent processors from Rockchip.

Applied to the togreg branch of iio.git.
I have exercised a small amount of discretion wrt to the standard 3 weeks
as there really is very little different in here from previous versions
and no one has raised any comments on them.

Did the binding patch make it into any tree? Because when I grep for saradc in
either linux-next or the iio tree I only get patch 1/2 (the driver itself) but
the binding document is somehow missing.

Good spot. Interestingly I had the file in my local tree but not the commit.
Odd, but now applied to the togreg branch of iio.git and pushed out.

Sorry about that!

Jonathan

Post by Heiko Stübner
Thanks
Heiko

Post by Jonathan Cameron
It's nearly 3 weeks anyway!
J

Post by Heiko Stübner
---
- remove clock-frquency property as described in patch 1/2
.../bindings/iio/adc/rockchip-saradc.txt | 24
++++++++++++++++++++++ 1 file changed, 24 insertions(+)
create mode 100644
Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt>
diff --git a/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
b/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt new file
mode 100644
index 0000000..5d3ec1d
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
@@ -0,0 +1,24 @@
+Rockchip Successive Approximation Register (SAR) A/D Converter bindings
+
+- compatible: Should be "rockchip,saradc"
+- reg: physical base address of the controller and length of memory mapped
+ region.
+- interrupts: The interrupt number to the cpu. The interrupt specifier
format + depends on the interrupt controller.
+- clocks: Must contain an entry for each entry in clock-names.
+- clock-names: Shall be "saradc" for the converter-clock, and "apb_pclk"
for + the peripheral clock.
+- vref-supply: The regulator supply ADC reference voltage.
+- #io-channel-cells: Should be 1, see ../iio-bindings.txt
+
+ compatible = "rockchip,saradc";
+ reg = <0x2006c000 0x100>;
+ interrupts = <GIC_SPI 26 IRQ_TYPE_LEVEL_HIGH>;
+ clocks = <&cru SCLK_SARADC>, <&cru PCLK_SARADC>;
+ clock-names = "saradc", "apb_pclk";
+ #io-channel-cells = <1>;
+ vref-supply = <&vcc18>;
+ };

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