// SPDX-License-Identifier: GPL-2.0-only /* * Driver for ADC module on the Cirrus Logic EP93xx series of SoCs * * Copyright (C) 2015 Alexander Sverdlin * * The driver uses polling to get the conversion status. According to EP93xx * datasheets, reading ADCResult register starts the conversion, but user is also * responsible for ensuring that delay between adjacent conversion triggers is * long enough so that maximum allowed conversion rate is not exceeded. This * basically renders IRQ mode unusable. */ #include <linux/clk.h> #include <linux/delay.h> #include <linux/device.h> #include <linux/err.h> #include <linux/iio/iio.h> #include <linux/io.h> #include <linux/irqflags.h> #include <linux/module.h> #include <linux/mutex.h> #include <linux/platform_device.h> #include <linux/of.h> /* * This code could benefit from real HR Timers, but jiffy granularity would * lower ADC conversion rate down to CONFIG_HZ, so we fallback to busy wait * in such case. * * HR Timers-based version loads CPU only up to 10% during back to back ADC * conversion, while busy wait-based version consumes whole CPU power. */ #ifdef CONFIG_HIGH_RES_TIMERS #define ep93xx_adc_delay(usmin, usmax) … #else #define ep93xx_adc_delay … #endif #define EP93XX_ADC_RESULT … #define EP93XX_ADC_SDR … #define EP93XX_ADC_SWITCH … #define EP93XX_ADC_SW_LOCK … struct ep93xx_adc_priv { … }; #define EP93XX_ADC_CH(index, dname, swcfg) … /* * Numbering scheme for channels 0..4 is defined in EP9301 and EP9302 datasheets. * EP9307, EP9312 and EP9312 have 3 channels more (total 8), but the numbering is * not defined. So the last three are numbered randomly, let's say. */ static const struct iio_chan_spec ep93xx_adc_channels[8] = …; static int ep93xx_read_raw(struct iio_dev *iiodev, struct iio_chan_spec const *channel, int *value, int *shift, long mask) { … } static const struct iio_info ep93xx_adc_info = …; static int ep93xx_adc_probe(struct platform_device *pdev) { … } static void ep93xx_adc_remove(struct platform_device *pdev) { … } static const struct of_device_id ep93xx_adc_of_ids[] = …; MODULE_DEVICE_TABLE(of, ep93xx_adc_of_ids); static struct platform_driver ep93xx_adc_driver = …; module_platform_driver(…) …; MODULE_AUTHOR(…) …; MODULE_DESCRIPTION(…) …; MODULE_LICENSE(…) …; MODULE_ALIAS(…) …;
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