/* * 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");