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224 lines
5.2 KiB
224 lines
5.2 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* IIO ADC driver for NXP LPC18xx ADC |
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* |
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* Copyright (C) 2016 Joachim Eastwood <[email protected]> |
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* |
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* UNSUPPORTED hardware features: |
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* - Hardware triggers |
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* - Burst mode |
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* - Interrupts |
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* - DMA |
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*/ |
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#include <linux/clk.h> |
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#include <linux/err.h> |
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#include <linux/iio/iio.h> |
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#include <linux/iio/driver.h> |
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#include <linux/io.h> |
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#include <linux/iopoll.h> |
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#include <linux/module.h> |
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#include <linux/mutex.h> |
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#include <linux/of.h> |
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#include <linux/of_device.h> |
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#include <linux/platform_device.h> |
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#include <linux/regulator/consumer.h> |
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/* LPC18XX ADC registers and bits */ |
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#define LPC18XX_ADC_CR 0x000 |
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#define LPC18XX_ADC_CR_CLKDIV_SHIFT 8 |
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#define LPC18XX_ADC_CR_PDN BIT(21) |
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#define LPC18XX_ADC_CR_START_NOW (0x1 << 24) |
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#define LPC18XX_ADC_GDR 0x004 |
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/* Data register bits */ |
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#define LPC18XX_ADC_SAMPLE_SHIFT 6 |
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#define LPC18XX_ADC_SAMPLE_MASK 0x3ff |
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#define LPC18XX_ADC_CONV_DONE BIT(31) |
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/* Clock should be 4.5 MHz or less */ |
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#define LPC18XX_ADC_CLK_TARGET 4500000 |
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struct lpc18xx_adc { |
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struct regulator *vref; |
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void __iomem *base; |
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struct device *dev; |
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struct mutex lock; |
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struct clk *clk; |
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u32 cr_reg; |
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}; |
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#define LPC18XX_ADC_CHAN(_idx) { \ |
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.type = IIO_VOLTAGE, \ |
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.indexed = 1, \ |
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.channel = _idx, \ |
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.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ |
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.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ |
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} |
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static const struct iio_chan_spec lpc18xx_adc_iio_channels[] = { |
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LPC18XX_ADC_CHAN(0), |
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LPC18XX_ADC_CHAN(1), |
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LPC18XX_ADC_CHAN(2), |
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LPC18XX_ADC_CHAN(3), |
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LPC18XX_ADC_CHAN(4), |
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LPC18XX_ADC_CHAN(5), |
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LPC18XX_ADC_CHAN(6), |
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LPC18XX_ADC_CHAN(7), |
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}; |
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static int lpc18xx_adc_read_chan(struct lpc18xx_adc *adc, unsigned int ch) |
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{ |
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int ret; |
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u32 reg; |
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reg = adc->cr_reg | BIT(ch) | LPC18XX_ADC_CR_START_NOW; |
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writel(reg, adc->base + LPC18XX_ADC_CR); |
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ret = readl_poll_timeout(adc->base + LPC18XX_ADC_GDR, reg, |
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reg & LPC18XX_ADC_CONV_DONE, 3, 9); |
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if (ret) { |
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dev_warn(adc->dev, "adc read timed out\n"); |
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return ret; |
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} |
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return (reg >> LPC18XX_ADC_SAMPLE_SHIFT) & LPC18XX_ADC_SAMPLE_MASK; |
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} |
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static int lpc18xx_adc_read_raw(struct iio_dev *indio_dev, |
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struct iio_chan_spec const *chan, |
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int *val, int *val2, long mask) |
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{ |
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struct lpc18xx_adc *adc = iio_priv(indio_dev); |
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switch (mask) { |
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case IIO_CHAN_INFO_RAW: |
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mutex_lock(&adc->lock); |
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*val = lpc18xx_adc_read_chan(adc, chan->channel); |
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mutex_unlock(&adc->lock); |
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if (*val < 0) |
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return *val; |
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return IIO_VAL_INT; |
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case IIO_CHAN_INFO_SCALE: |
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*val = regulator_get_voltage(adc->vref) / 1000; |
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*val2 = 10; |
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return IIO_VAL_FRACTIONAL_LOG2; |
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} |
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return -EINVAL; |
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} |
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static const struct iio_info lpc18xx_adc_info = { |
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.read_raw = lpc18xx_adc_read_raw, |
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}; |
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static int lpc18xx_adc_probe(struct platform_device *pdev) |
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{ |
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struct iio_dev *indio_dev; |
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struct lpc18xx_adc *adc; |
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unsigned int clkdiv; |
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unsigned long rate; |
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int ret; |
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indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*adc)); |
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if (!indio_dev) |
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return -ENOMEM; |
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platform_set_drvdata(pdev, indio_dev); |
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adc = iio_priv(indio_dev); |
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adc->dev = &pdev->dev; |
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mutex_init(&adc->lock); |
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adc->base = devm_platform_ioremap_resource(pdev, 0); |
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if (IS_ERR(adc->base)) |
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return PTR_ERR(adc->base); |
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adc->clk = devm_clk_get(&pdev->dev, NULL); |
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if (IS_ERR(adc->clk)) { |
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dev_err(&pdev->dev, "error getting clock\n"); |
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return PTR_ERR(adc->clk); |
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} |
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rate = clk_get_rate(adc->clk); |
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clkdiv = DIV_ROUND_UP(rate, LPC18XX_ADC_CLK_TARGET); |
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adc->vref = devm_regulator_get(&pdev->dev, "vref"); |
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if (IS_ERR(adc->vref)) { |
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dev_err(&pdev->dev, "error getting regulator\n"); |
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return PTR_ERR(adc->vref); |
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} |
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indio_dev->name = dev_name(&pdev->dev); |
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indio_dev->info = &lpc18xx_adc_info; |
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indio_dev->modes = INDIO_DIRECT_MODE; |
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indio_dev->channels = lpc18xx_adc_iio_channels; |
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indio_dev->num_channels = ARRAY_SIZE(lpc18xx_adc_iio_channels); |
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ret = regulator_enable(adc->vref); |
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if (ret) { |
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dev_err(&pdev->dev, "unable to enable regulator\n"); |
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return ret; |
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} |
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ret = clk_prepare_enable(adc->clk); |
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if (ret) { |
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dev_err(&pdev->dev, "unable to enable clock\n"); |
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goto dis_reg; |
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} |
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adc->cr_reg = (clkdiv << LPC18XX_ADC_CR_CLKDIV_SHIFT) | |
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LPC18XX_ADC_CR_PDN; |
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writel(adc->cr_reg, adc->base + LPC18XX_ADC_CR); |
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ret = iio_device_register(indio_dev); |
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if (ret) { |
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dev_err(&pdev->dev, "unable to register device\n"); |
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goto dis_clk; |
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} |
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return 0; |
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dis_clk: |
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writel(0, adc->base + LPC18XX_ADC_CR); |
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clk_disable_unprepare(adc->clk); |
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dis_reg: |
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regulator_disable(adc->vref); |
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return ret; |
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} |
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static int lpc18xx_adc_remove(struct platform_device *pdev) |
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{ |
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struct iio_dev *indio_dev = platform_get_drvdata(pdev); |
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struct lpc18xx_adc *adc = iio_priv(indio_dev); |
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iio_device_unregister(indio_dev); |
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writel(0, adc->base + LPC18XX_ADC_CR); |
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clk_disable_unprepare(adc->clk); |
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regulator_disable(adc->vref); |
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return 0; |
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} |
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static const struct of_device_id lpc18xx_adc_match[] = { |
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{ .compatible = "nxp,lpc1850-adc" }, |
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{ /* sentinel */ } |
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}; |
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MODULE_DEVICE_TABLE(of, lpc18xx_adc_match); |
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static struct platform_driver lpc18xx_adc_driver = { |
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.probe = lpc18xx_adc_probe, |
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.remove = lpc18xx_adc_remove, |
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.driver = { |
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.name = "lpc18xx-adc", |
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.of_match_table = lpc18xx_adc_match, |
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}, |
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}; |
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module_platform_driver(lpc18xx_adc_driver); |
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MODULE_DESCRIPTION("LPC18xx ADC driver"); |
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MODULE_AUTHOR("Joachim Eastwood <[email protected]>"); |
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MODULE_LICENSE("GPL v2");
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