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/*
* IIO DAC driver for NXP LPC18xx DAC
*
* 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:
* - 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 DAC registers and bits */
#define LPC18XX_DAC_CR 0x000
#define LPC18XX_DAC_CR_VALUE_SHIFT 6
#define LPC18XX_DAC_CR_VALUE_MASK 0x3ff
#define LPC18XX_DAC_CR_BIAS BIT(16)
#define LPC18XX_DAC_CTRL 0x004
#define LPC18XX_DAC_CTRL_DMA_ENA BIT(3)
struct lpc18xx_dac {
struct regulator *vref;
void __iomem *base;
struct mutex lock;
struct clk *clk;
};
static const struct iio_chan_spec lpc18xx_dac_iio_channels[] = {
{
.type = IIO_VOLTAGE,
.output = 1,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
BIT(IIO_CHAN_INFO_SCALE),
},
};
static int lpc18xx_dac_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long mask)
{
struct lpc18xx_dac *dac = iio_priv(indio_dev);
u32 reg;
switch (mask) {
case IIO_CHAN_INFO_RAW:
reg = readl(dac->base + LPC18XX_DAC_CR);
*val = reg >> LPC18XX_DAC_CR_VALUE_SHIFT;
*val &= LPC18XX_DAC_CR_VALUE_MASK;
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
*val = regulator_get_voltage(dac->vref) / 1000;
*val2 = 10;
return IIO_VAL_FRACTIONAL_LOG2;
}
return -EINVAL;
}
static int lpc18xx_dac_write_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int val, int val2, long mask)
{
struct lpc18xx_dac *dac = iio_priv(indio_dev);
u32 reg;
switch (mask) {
case IIO_CHAN_INFO_RAW:
if (val < 0 || val > LPC18XX_DAC_CR_VALUE_MASK)
return -EINVAL;
reg = LPC18XX_DAC_CR_BIAS;
reg |= val << LPC18XX_DAC_CR_VALUE_SHIFT;
mutex_lock(&dac->lock);
writel(reg, dac->base + LPC18XX_DAC_CR);
writel(LPC18XX_DAC_CTRL_DMA_ENA, dac->base + LPC18XX_DAC_CTRL);
mutex_unlock(&dac->lock);
return 0;
}
return -EINVAL;
}
static const struct iio_info lpc18xx_dac_info = {
.read_raw = lpc18xx_dac_read_raw,
.write_raw = lpc18xx_dac_write_raw,
};
static int lpc18xx_dac_probe(struct platform_device *pdev)
{
struct iio_dev *indio_dev;
struct lpc18xx_dac *dac;
struct resource *res;
int ret;
indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*dac));
if (!indio_dev)
return -ENOMEM;
platform_set_drvdata(pdev, indio_dev);
dac = iio_priv(indio_dev);
mutex_init(&dac->lock);
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
dac->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(dac->base))
return PTR_ERR(dac->base);
dac->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(dac->clk)) {
dev_err(&pdev->dev, "error getting clock\n");
return PTR_ERR(dac->clk);
}
dac->vref = devm_regulator_get(&pdev->dev, "vref");
if (IS_ERR(dac->vref)) {
dev_err(&pdev->dev, "error getting regulator\n");
return PTR_ERR(dac->vref);
}
indio_dev->name = dev_name(&pdev->dev);
indio_dev->dev.parent = &pdev->dev;
indio_dev->info = &lpc18xx_dac_info;
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->channels = lpc18xx_dac_iio_channels;
indio_dev->num_channels = ARRAY_SIZE(lpc18xx_dac_iio_channels);
ret = regulator_enable(dac->vref);
if (ret) {
dev_err(&pdev->dev, "unable to enable regulator\n");
return ret;
}
ret = clk_prepare_enable(dac->clk);
if (ret) {
dev_err(&pdev->dev, "unable to enable clock\n");
goto dis_reg;
}
writel(0, dac->base + LPC18XX_DAC_CTRL);
writel(0, dac->base + LPC18XX_DAC_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:
clk_disable_unprepare(dac->clk);
dis_reg:
regulator_disable(dac->vref);
return ret;
}
static int lpc18xx_dac_remove(struct platform_device *pdev)
{
struct iio_dev *indio_dev = platform_get_drvdata(pdev);
struct lpc18xx_dac *dac = iio_priv(indio_dev);
iio_device_unregister(indio_dev);
writel(0, dac->base + LPC18XX_DAC_CTRL);
clk_disable_unprepare(dac->clk);
regulator_disable(dac->vref);
return 0;
}
static const struct of_device_id lpc18xx_dac_match[] = {
{ .compatible = "nxp,lpc1850-dac" },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, lpc18xx_dac_match);
static struct platform_driver lpc18xx_dac_driver = {
.probe = lpc18xx_dac_probe,
.remove = lpc18xx_dac_remove,
.driver = {
.name = "lpc18xx-dac",
.of_match_table = lpc18xx_dac_match,
},
};
module_platform_driver(lpc18xx_dac_driver);
MODULE_DESCRIPTION("LPC18xx DAC driver");
MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>");
MODULE_LICENSE("GPL v2");
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