Add base support for the 10-bit SAR ADC peripheral found
on NXP LPC18xx/43xx SoCs.
This is a minimal driver that does not support burst mode,
interrupts, DMA or hardware triggers.
User manual with register description can be found on:
LPC18xx: www.nxp.com/documents/user_manual/UM10430.pdf
LPC43xx: www.nxp.com/documents/user_manual/UM10503.pdf
Signed-off-by: Joachim Eastwood <manabian@xxxxxxxxx>
---
drivers/iio/adc/Kconfig | 10 ++
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/lpc18xx_adc.c | 231 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 242 insertions(+)
create mode 100644 drivers/iio/adc/lpc18xx_adc.c
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index a8819a08a828..9ddcd5db039b 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -235,6 +235,16 @@ config LP8788_ADC
To compile this driver as a module, choose M here: the module will be
called lp8788_adc.
+config LPC18XX_ADC
+ tristate "NXP LPC18xx ADC driver"
+ depends on ARCH_LPC18XX || COMPILE_TEST
+ depends on OF && HAS_IOMEM
+ help
+ Say yes here to build support for NXP LPC18XX ADC.
+
+ To compile this driver as a module, choose M here: the module will be
+ called lpc18xx_adc.
+
config MAX1027
tristate "Maxim max1027 ADC driver"
depends on SPI
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index b1aa456e6af3..1a4ac4590857 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -24,6 +24,7 @@ obj-$(CONFIG_HI8435) += hi8435.o
obj-$(CONFIG_IMX7D_ADC) += imx7d_adc.o
obj-$(CONFIG_INA2XX_ADC) += ina2xx-adc.o
obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
+obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o
obj-$(CONFIG_MAX1027) += max1027.o
obj-$(CONFIG_MAX1363) += max1363.o
obj-$(CONFIG_MCP320X) += mcp320x.o
diff --git a/drivers/iio/adc/lpc18xx_adc.c b/drivers/iio/adc/lpc18xx_adc.c
new file mode 100644
index 000000000000..3ef18f4b27f0
--- /dev/null
+++ b/drivers/iio/adc/lpc18xx_adc.c
@@ -0,0 +1,231 @@
+/*
+ * IIO ADC driver for NXP LPC18xx ADC
+ *
+ * Copyright (C) 2016 Joachim Eastwood <manabian@xxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * UNSUPPORTED hardware features:
+ * - Hardware triggers
+ * - Burst mode
+ * - Interrupts
+ * - DMA
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/driver.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+
+/* LPC18XX ADC registers and bits */
+#define LPC18XX_ADC_CR 0x000
+#define LPC18XX_ADC_CR_CLKDIV_SHIFT 8
+#define LPC18XX_ADC_CR_PDN BIT(21)
+#define LPC18XX_ADC_CR_START_NOW (0x1 << 24)
+#define LPC18XX_ADC_GDR 0x004
+
+/* Data register bits */
+#define LPC18XX_ADC_SAMPLE_SHIFT 6
+#define LPC18XX_ADC_SAMPLE_MASK 0x3ff
+#define LPC18XX_ADC_CONV_DONE BIT(31)
+
+/* Clock should be 4.5 MHz or less */
+#define LPC18XX_ADC_CLK_TARGET 4500000
+
+struct lpc18xx_adc {
+ struct regulator *vref;
+ void __iomem *base;
+ struct device *dev;
+ struct mutex lock;
+ struct clk *clk;
+ u32 cr_reg;
+};
+
+#define LPC18XX_ADC_CHAN(_idx) { \
+ .type = IIO_VOLTAGE, \
+ .indexed = 1, \
+ .channel = _idx, \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+}
+
+static const struct iio_chan_spec lpc18xx_adc_iio_channels[] = {
+ LPC18XX_ADC_CHAN(0),
+ LPC18XX_ADC_CHAN(1),
+ LPC18XX_ADC_CHAN(2),
+ LPC18XX_ADC_CHAN(3),
+ LPC18XX_ADC_CHAN(4),
+ LPC18XX_ADC_CHAN(5),
+ LPC18XX_ADC_CHAN(6),
+ LPC18XX_ADC_CHAN(7),
+};
+
+static int lpc18xx_adc_read_chan(struct lpc18xx_adc *adc, unsigned int ch)
+{
+ int ret;
+ u32 reg;
+
+ reg = adc->cr_reg | BIT(ch) | LPC18XX_ADC_CR_START_NOW;
+ writel(reg, adc->base + LPC18XX_ADC_CR);
+
+ ret = readl_poll_timeout(adc->base + LPC18XX_ADC_GDR, reg,
+ reg & LPC18XX_ADC_CONV_DONE, 3, 9);
+ if (ret) {
+ dev_warn(adc->dev, "adc read timed out\n");
+ return ret;
+ }
+
+ return (reg >> LPC18XX_ADC_SAMPLE_SHIFT) & LPC18XX_ADC_SAMPLE_MASK;
+}
+
+static int lpc18xx_adc_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long mask)
+{
+ struct lpc18xx_adc *adc = iio_priv(indio_dev);
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ mutex_lock(&adc->lock);
+ *val = lpc18xx_adc_read_chan(adc, chan->channel);
+ mutex_unlock(&adc->lock);
+ if (*val < 0)
+ return *val;
+
+ return IIO_VAL_INT;
+
+ case IIO_CHAN_INFO_SCALE:
+ *val = regulator_get_voltage(adc->vref) / 1000;
+ *val2 = 10;
+
+ return IIO_VAL_FRACTIONAL_LOG2;
+ }
+
+ return -EINVAL;
+}
+
+static const struct iio_info lpc18xx_adc_info = {
+ .read_raw = lpc18xx_adc_read_raw,
+ .driver_module = THIS_MODULE,
+};
+
+static int lpc18xx_adc_probe(struct platform_device *pdev)
+{
+ struct iio_dev *indio_dev;
+ struct lpc18xx_adc *adc;
+ struct resource *res;
+ unsigned int clkdiv;
+ unsigned long rate;
+ int ret;
+
+ indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*adc));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ platform_set_drvdata(pdev, indio_dev);
+ adc = iio_priv(indio_dev);
+ adc->dev = &pdev->dev;
+ mutex_init(&adc->lock);
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ adc->base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(adc->base))
+ return PTR_ERR(adc->base);
+
+ adc->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(adc->clk)) {
+ dev_err(&pdev->dev, "error getting clock\n");
+ return PTR_ERR(adc->clk);
+ }
+
+ rate = clk_get_rate(adc->clk);
+ clkdiv = DIV_ROUND_UP(rate, LPC18XX_ADC_CLK_TARGET);
+
+ adc->vref = devm_regulator_get(&pdev->dev, "vref");
+ if (IS_ERR(adc->vref)) {
+ dev_err(&pdev->dev, "error getting regulator\n");
+ return PTR_ERR(adc->vref);
+ }
+
+ indio_dev->name = dev_name(&pdev->dev);
+ indio_dev->dev.parent = &pdev->dev;
+ indio_dev->info = &lpc18xx_adc_info;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->channels = lpc18xx_adc_iio_channels;
+ indio_dev->num_channels = ARRAY_SIZE(lpc18xx_adc_iio_channels);
+
+ ret = regulator_enable(adc->vref);
+ if (ret) {
+ dev_err(&pdev->dev, "unable to enable regulator\n");
+ return ret;
+ }
+
+ ret = clk_prepare_enable(adc->clk);
+ if (ret) {
+ dev_err(&pdev->dev, "unable to enable clock\n");
+ goto dis_reg;
+ }
+
+ adc->cr_reg = (clkdiv << LPC18XX_ADC_CR_CLKDIV_SHIFT) |
+ LPC18XX_ADC_CR_PDN;
+ writel(adc->cr_reg, adc->base + LPC18XX_ADC_CR);
+
+ ret = iio_device_register(indio_dev);
+ if (ret) {
+ dev_err(&pdev->dev, "unable to register device\n");
+ goto dis_clk;
+ }
+
+ return 0;
+
+dis_clk:
+ writel(0, adc->base + LPC18XX_ADC_CR);
+ clk_disable_unprepare(adc->clk);
+dis_reg:
+ regulator_disable(adc->vref);
+ return ret;
+}
+
+static int lpc18xx_adc_remove(struct platform_device *pdev)
+{
+ struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+ struct lpc18xx_adc *adc = iio_priv(indio_dev);
+
+ iio_device_unregister(indio_dev);
+
+ writel(0, adc->base + LPC18XX_ADC_CR);
+ clk_disable_unprepare(adc->clk);
+ regulator_disable(adc->vref);
+
+ return 0;
+}
+
+static const struct of_device_id lpc18xx_adc_match[] = {
+ { .compatible = "nxp,lpc1850-adc" },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, lpc18xx_adc_match);
+
+static struct platform_driver lpc18xx_adc_driver = {
+ .probe = lpc18xx_adc_probe,
+ .remove = lpc18xx_adc_remove,
+ .driver = {
+ .name = "lpc18xx-adc",
+ .of_match_table = lpc18xx_adc_match,
+ },
+};
+module_platform_driver(lpc18xx_adc_driver);
+
+MODULE_DESCRIPTION("LPC18xx ADC driver");
+MODULE_AUTHOR("Joachim Eastwood <manabian@xxxxxxxxx>");
+MODULE_LICENSE("GPL v2");
--
1.8.0
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