/*
* IIO ADC driver for NXP LPC18xx ADC
*
* Copyright (C) 2016 Joachim Eastwood <manabian@gmail.com>
*
* 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,
};
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@gmail.com>");
MODULE_LICENSE("GPL v2");
