diff options
Diffstat (limited to 'drivers/iio/adc/lpc18xx_adc.c')
| -rw-r--r-- | drivers/iio/adc/lpc18xx_adc.c | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/drivers/iio/adc/lpc18xx_adc.c b/drivers/iio/adc/lpc18xx_adc.c new file mode 100644 index 000000000..450a243d1 --- /dev/null +++ b/drivers/iio/adc/lpc18xx_adc.c @@ -0,0 +1,206 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * IIO ADC driver for NXP LPC18xx ADC + * + * Copyright (C) 2016 Joachim Eastwood <manabian@gmail.com> + * + * 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/mod_devicetable.h> +#include <linux/module.h> +#include <linux/mutex.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 void lpc18xx_clear_cr_reg(void *data) +{ + struct lpc18xx_adc *adc = data; + + writel(0, adc->base + LPC18XX_ADC_CR); +} + +static void lpc18xx_regulator_disable(void *vref) +{ + regulator_disable(vref); +} + +static int lpc18xx_adc_probe(struct platform_device *pdev) +{ + struct iio_dev *indio_dev; + struct lpc18xx_adc *adc; + unsigned int clkdiv; + unsigned long rate; + int ret; + + indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*adc)); + if (!indio_dev) + return -ENOMEM; + + adc = iio_priv(indio_dev); + adc->dev = &pdev->dev; + mutex_init(&adc->lock); + + adc->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(adc->base)) + return PTR_ERR(adc->base); + + adc->clk = devm_clk_get_enabled(&pdev->dev, NULL); + if (IS_ERR(adc->clk)) + return dev_err_probe(&pdev->dev, PTR_ERR(adc->clk), + "error getting clock\n"); + + adc->vref = devm_regulator_get(&pdev->dev, "vref"); + if (IS_ERR(adc->vref)) + return dev_err_probe(&pdev->dev, PTR_ERR(adc->vref), + "error getting regulator\n"); + + indio_dev->name = dev_name(&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 = devm_add_action_or_reset(&pdev->dev, lpc18xx_regulator_disable, adc->vref); + if (ret) + return ret; + + rate = clk_get_rate(adc->clk); + clkdiv = DIV_ROUND_UP(rate, LPC18XX_ADC_CLK_TARGET); + + adc->cr_reg = (clkdiv << LPC18XX_ADC_CR_CLKDIV_SHIFT) | + LPC18XX_ADC_CR_PDN; + writel(adc->cr_reg, adc->base + LPC18XX_ADC_CR); + + ret = devm_add_action_or_reset(&pdev->dev, lpc18xx_clear_cr_reg, adc); + if (ret) + return ret; + + return devm_iio_device_register(&pdev->dev, indio_dev); +} + +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, + .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"); |