iio:adc:at91_adc8xx: introduce new atmel adc driver

This driver supports the new version of the Atmel ADC device introduced
with the SAMA5D2 SoC family.
Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt

+* AT91 SAMA5D2 Analog to Digital Converter (ADC)
+
+Required properties:
+  - compatible: Should be "atmel,sama5d2-adc".
+  - reg: Should contain ADC registers location and length.
+  - interrupts: Should contain the IRQ line for the ADC.
+  - clocks: phandle to device clock.
+  - clock-names: Must be "adc_clk".
+  - vref-supply: Supply used as reference for conversions.
+  - vddana-supply: Supply for the adc device.
+  - atmel,min-sample-rate-hz: Minimum sampling rate, it depends on SoC.
+  - atmel,max-sample-rate-hz: Maximum sampling rate, it depends on SoC.
+  - atmel,startup-time-ms: Startup time expressed in ms, it depends on SoC.
+
+Example:
+
+adc: adc@fc030000 {
+	compatible = "atmel,sama5d2-adc";
+	reg = <0xfc030000 0x100>;
+	interrupts = <40 IRQ_TYPE_LEVEL_HIGH 7>;
+	clocks = <&adc_clk>;
+	clock-names = "adc_clk";
+	atmel,min-sample-rate-hz = <200000>;
+	atmel,max-sample-rate-hz = <20000000>;
+	atmel,startup-time-ms = <4>;
+	vddana-supply = <&vdd_3v3_lp_reg>;
+	vref-supply = <&vdd_3v3_lp_reg>;
+}

drivers/iio/adc/Kconfig

@@ -131,6 +131,17 @@ config AT91_ADC
 	  To compile this driver as a module, choose M here: the module will be
 	  called at91_adc.
 
+config AT91_SAMA5D2_ADC
+	tristate "Atmel AT91 SAMA5D2 ADC"
+	depends on ARCH_AT91
+	depends on INPUT
+	help
+	  Say yes here to build support for Atmel SAMA5D2 ADC which is
+	  available on SAMA5D2 SoC family.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called at91-sama5d2_adc.
+
 config AXP288_ADC
 	tristate "X-Powers AXP288 ADC driver"
 	depends on MFD_AXP20X

drivers/iio/adc/Makefile

@@ -14,6 +14,7 @@ obj-$(CONFIG_AD7793) += ad7793.o
 obj-$(CONFIG_AD7887) += ad7887.o
 obj-$(CONFIG_AD799X) += ad799x.o
 obj-$(CONFIG_AT91_ADC) += at91_adc.o
+obj-$(CONFIG_AT91_SAMA5D2_ADC) += at91-sama5d2_adc.o
 obj-$(CONFIG_AXP288_ADC) += axp288_adc.o
 obj-$(CONFIG_BERLIN2_ADC) += berlin2-adc.o
 obj-$(CONFIG_CC10001_ADC) += cc10001_adc.o

drivers/iio/adc/at91-sama5d2_adc.c

+/*
+ * Atmel ADC driver for SAMA5D2 devices and compatible.
+ *
+ * Copyright (C) 2015 Atmel,
+ *               2015 Ludovic Desroches <ludovic.desroches@atmel.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/regulator/consumer.h>
+
+/* Control Register */
+#define AT91_SAMA5D2_CR		0x00
+/* Software Reset */
+#define	AT91_SAMA5D2_CR_SWRST		BIT(0)
+/* Start Conversion */
+#define	AT91_SAMA5D2_CR_START		BIT(1)
+/* Touchscreen Calibration */
+#define	AT91_SAMA5D2_CR_TSCALIB		BIT(2)
+/* Comparison Restart */
+#define	AT91_SAMA5D2_CR_CMPRST		BIT(4)
+
+/* Mode Register */
+#define AT91_SAMA5D2_MR		0x04
+/* Trigger Selection */
+#define	AT91_SAMA5D2_MR_TRGSEL(v)	((v) << 1)
+/* ADTRG */
+#define	AT91_SAMA5D2_MR_TRGSEL_TRIG0	0
+/* TIOA0 */
+#define	AT91_SAMA5D2_MR_TRGSEL_TRIG1	1
+/* TIOA1 */
+#define	AT91_SAMA5D2_MR_TRGSEL_TRIG2	2
+/* TIOA2 */
+#define	AT91_SAMA5D2_MR_TRGSEL_TRIG3	3
+/* PWM event line 0 */
+#define	AT91_SAMA5D2_MR_TRGSEL_TRIG4	4
+/* PWM event line 1 */
+#define	AT91_SAMA5D2_MR_TRGSEL_TRIG5	5
+/* TIOA3 */
+#define	AT91_SAMA5D2_MR_TRGSEL_TRIG6	6
+/* RTCOUT0 */
+#define	AT91_SAMA5D2_MR_TRGSEL_TRIG7	7
+/* Sleep Mode */
+#define	AT91_SAMA5D2_MR_SLEEP		BIT(5)
+/* Fast Wake Up */
+#define	AT91_SAMA5D2_MR_FWUP		BIT(6)
+/* Prescaler Rate Selection */
+#define	AT91_SAMA5D2_MR_PRESCAL(v)	((v) << AT91_SAMA5D2_MR_PRESCAL_OFFSET)
+#define	AT91_SAMA5D2_MR_PRESCAL_OFFSET	8
+#define	AT91_SAMA5D2_MR_PRESCAL_MAX	0xff
+/* Startup Time */
+#define	AT91_SAMA5D2_MR_STARTUP(v)	((v) << 16)
+/* Analog Change */
+#define	AT91_SAMA5D2_MR_ANACH		BIT(23)
+/* Tracking Time */
+#define	AT91_SAMA5D2_MR_TRACKTIM(v)	((v) << 24)
+#define	AT91_SAMA5D2_MR_TRACKTIM_MAX	0xff
+/* Transfer Time */
+#define	AT91_SAMA5D2_MR_TRANSFER(v)	((v) << 28)
+#define	AT91_SAMA5D2_MR_TRANSFER_MAX	0x3
+/* Use Sequence Enable */
+#define	AT91_SAMA5D2_MR_USEQ		BIT(31)
+
+/* Channel Sequence Register 1 */
+#define AT91_SAMA5D2_SEQR1	0x08
+/* Channel Sequence Register 2 */
+#define AT91_SAMA5D2_SEQR2	0x0c
+/* Channel Enable Register */
+#define AT91_SAMA5D2_CHER	0x10
+/* Channel Disable Register */
+#define AT91_SAMA5D2_CHDR	0x14
+/* Channel Status Register */
+#define AT91_SAMA5D2_CHSR	0x18
+/* Last Converted Data Register */
+#define AT91_SAMA5D2_LCDR	0x20
+/* Interrupt Enable Register */
+#define AT91_SAMA5D2_IER		0x24
+/* Interrupt Disable Register */
+#define AT91_SAMA5D2_IDR		0x28
+/* Interrupt Mask Register */
+#define AT91_SAMA5D2_IMR		0x2c
+/* Interrupt Status Register */
+#define AT91_SAMA5D2_ISR		0x30
+/* Last Channel Trigger Mode Register */
+#define AT91_SAMA5D2_LCTMR	0x34
+/* Last Channel Compare Window Register */
+#define AT91_SAMA5D2_LCCWR	0x38
+/* Overrun Status Register */
+#define AT91_SAMA5D2_OVER	0x3c
+/* Extended Mode Register */
+#define AT91_SAMA5D2_EMR		0x40
+/* Compare Window Register */
+#define AT91_SAMA5D2_CWR		0x44
+/* Channel Gain Register */
+#define AT91_SAMA5D2_CGR		0x48
+/* Channel Offset Register */
+#define AT91_SAMA5D2_COR		0x4c
+/* Channel Data Register 0 */
+#define AT91_SAMA5D2_CDR0	0x50
+/* Analog Control Register */
+#define AT91_SAMA5D2_ACR		0x94
+/* Touchscreen Mode Register */
+#define AT91_SAMA5D2_TSMR	0xb0
+/* Touchscreen X Position Register */
+#define AT91_SAMA5D2_XPOSR	0xb4
+/* Touchscreen Y Position Register */
+#define AT91_SAMA5D2_YPOSR	0xb8
+/* Touchscreen Pressure Register */
+#define AT91_SAMA5D2_PRESSR	0xbc
+/* Trigger Register */
+#define AT91_SAMA5D2_TRGR	0xc0
+/* Correction Select Register */
+#define AT91_SAMA5D2_COSR	0xd0
+/* Correction Value Register */
+#define AT91_SAMA5D2_CVR		0xd4
+/* Channel Error Correction Register */
+#define AT91_SAMA5D2_CECR	0xd8
+/* Write Protection Mode Register */
+#define AT91_SAMA5D2_WPMR	0xe4
+/* Write Protection Status Register */
+#define AT91_SAMA5D2_WPSR	0xe8
+/* Version Register */
+#define AT91_SAMA5D2_VERSION	0xfc
+
+#define AT91_AT91_SAMA5D2_CHAN(num, addr)				\
+	{								\
+		.type = IIO_VOLTAGE,					\
+		.channel = num,						\
+		.address = addr,					\
+		.scan_type = {						\
+			.sign = 'u',					\
+			.realbits = 12,					\
+		},							\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),\
+		.datasheet_name = "CH"#num,				\
+		.indexed = 1,						\
+	}
+
+#define at91_adc_readl(st, reg)		readl_relaxed(st->base + reg)
+#define at91_adc_writel(st, reg, val)	writel_relaxed(val, st->base + reg)
+
+struct at91_adc_soc_info {
+	unsigned			startup_time;
+	unsigned			min_sample_rate;
+	unsigned			max_sample_rate;
+};
+
+struct at91_adc_state {
+	void __iomem			*base;
+	int				irq;
+	struct clk			*per_clk;
+	struct regulator		*reg;
+	struct regulator		*vref;
+	u32				vref_uv;
+	const struct iio_chan_spec	*chan;
+	bool				conversion_done;
+	u32				conversion_value;
+	struct at91_adc_soc_info	soc_info;
+	wait_queue_head_t		wq_data_available;
+	/*
+	 * lock to prevent concurrent 'single conversion' requests through
+	 * sysfs.
+	 */
+	struct mutex			lock;
+};
+
+static const struct iio_chan_spec at91_adc_channels[] = {
+	AT91_AT91_SAMA5D2_CHAN(0, 0x50),
+	AT91_AT91_SAMA5D2_CHAN(1, 0x54),
+	AT91_AT91_SAMA5D2_CHAN(2, 0x58),
+	AT91_AT91_SAMA5D2_CHAN(3, 0x5c),
+	AT91_AT91_SAMA5D2_CHAN(4, 0x60),
+	AT91_AT91_SAMA5D2_CHAN(5, 0x64),
+	AT91_AT91_SAMA5D2_CHAN(6, 0x68),
+	AT91_AT91_SAMA5D2_CHAN(7, 0x6c),
+	AT91_AT91_SAMA5D2_CHAN(8, 0x70),
+	AT91_AT91_SAMA5D2_CHAN(9, 0x74),
+	AT91_AT91_SAMA5D2_CHAN(10, 0x78),
+	AT91_AT91_SAMA5D2_CHAN(11, 0x7c),
+};
+
+static unsigned at91_adc_startup_time(unsigned startup_time_min,
+				      unsigned adc_clk_khz)
+{
+	const unsigned startup_lookup[] = {
+		  0,   8,  16,  24,
+		 64,  80,  96, 112,
+		512, 576, 640, 704,
+		768, 832, 896, 960
+		};
+	unsigned ticks_min, i;
+
+	/*
+	 * Since the adc frequency is checked before, there is no reason
+	 * to not meet the startup time constraint.
+	 */
+
+	ticks_min = startup_time_min * adc_clk_khz / 1000;
+	for (i = 0; i < ARRAY_SIZE(startup_lookup); i++)
+		if (startup_lookup[i] > ticks_min)
+			break;
+
+	return i;
+}
+
+static void at91_adc_setup_samp_freq(struct at91_adc_state *st, unsigned freq)
+{
+	struct iio_dev *indio_dev = iio_priv_to_dev(st);
+	unsigned f_per, prescal, startup;
+
+	f_per = clk_get_rate(st->per_clk);
+	prescal = (f_per / (2 * freq)) - 1;
+
+	startup = at91_adc_startup_time(st->soc_info.startup_time,
+					freq / 1000);
+
+	at91_adc_writel(st, AT91_SAMA5D2_MR,
+			AT91_SAMA5D2_MR_TRANSFER(2)
+			| AT91_SAMA5D2_MR_STARTUP(startup)
+			| AT91_SAMA5D2_MR_PRESCAL(prescal));
+
+	dev_dbg(&indio_dev->dev, "freq: %u, startup: %u, prescal: %u\n",
+		freq, startup, prescal);
+}
+
+static unsigned at91_adc_get_sample_freq(struct at91_adc_state *st)
+{
+	unsigned f_adc, f_per = clk_get_rate(st->per_clk);
+	unsigned mr, prescal;
+
+	mr = at91_adc_readl(st, AT91_SAMA5D2_MR);
+	prescal = (mr >> AT91_SAMA5D2_MR_PRESCAL_OFFSET)
+		  & AT91_SAMA5D2_MR_PRESCAL_MAX;
+	f_adc = f_per / (2 * (prescal + 1));
+
+	return f_adc;
+}
+
+static irqreturn_t at91_adc_interrupt(int irq, void *private)
+{
+	struct iio_dev *indio = private;
+	struct at91_adc_state *st = iio_priv(indio);
+	u32 status = at91_adc_readl(st, AT91_SAMA5D2_ISR);
+	u32 imr = at91_adc_readl(st, AT91_SAMA5D2_IMR);
+
+	if (status & imr) {
+		st->conversion_value = at91_adc_readl(st, st->chan->address);
+		st->conversion_done = true;
+		wake_up_interruptible(&st->wq_data_available);
+		return IRQ_HANDLED;
+	}
+
+	return IRQ_NONE;
+}
+
+static int at91_adc_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int *val, int *val2, long mask)
+{
+	struct at91_adc_state *st = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&st->lock);
+
+		st->chan = chan;
+
+		at91_adc_writel(st, AT91_SAMA5D2_CHER, BIT(chan->channel));
+		at91_adc_writel(st, AT91_SAMA5D2_IER, BIT(chan->channel));
+		at91_adc_writel(st, AT91_SAMA5D2_CR, AT91_SAMA5D2_CR_START);
+
+		ret = wait_event_interruptible_timeout(st->wq_data_available,
+						       st->conversion_done,
+						       msecs_to_jiffies(1000));
+		if (ret == 0)
+			ret = -ETIMEDOUT;
+
+		if (ret > 0) {
+			*val = st->conversion_value;
+			ret = IIO_VAL_INT;
+			st->conversion_done = false;
+		}
+
+		at91_adc_writel(st, AT91_SAMA5D2_IDR, BIT(chan->channel));
+		at91_adc_writel(st, AT91_SAMA5D2_CHDR, BIT(chan->channel));
+
+		mutex_unlock(&st->lock);
+		return ret;
+
+	case IIO_CHAN_INFO_SCALE:
+		*val = st->vref_uv / 1000;
+		*val2 = chan->scan_type.realbits;
+		return IIO_VAL_FRACTIONAL_LOG2;
+
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*val = at91_adc_get_sample_freq(st);
+		return IIO_VAL_INT;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int at91_adc_write_raw(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan,
+			      int val, int val2, long mask)
+{
+	struct at91_adc_state *st = iio_priv(indio_dev);
+
+	if (mask != IIO_CHAN_INFO_SAMP_FREQ)
+		return -EINVAL;
+
+	if (val < st->soc_info.min_sample_rate ||
+	    val > st->soc_info.max_sample_rate)
+		return -EINVAL;
+
+	at91_adc_setup_samp_freq(st, val);
+
+	return 0;
+}
+
+static const struct iio_info at91_adc_info = {
+	.read_raw = &at91_adc_read_raw,
+	.write_raw = &at91_adc_write_raw,
+	.driver_module = THIS_MODULE,
+};
+
+static int at91_adc_probe(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev;
+	struct at91_adc_state *st;
+	struct resource	*res;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&pdev->dev,
+					  sizeof(struct at91_adc_state));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	indio_dev->dev.parent = &pdev->dev;
+	indio_dev->name = dev_name(&pdev->dev);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &at91_adc_info;
+	indio_dev->channels = at91_adc_channels;
+	indio_dev->num_channels = ARRAY_SIZE(at91_adc_channels);
+
+	st = iio_priv(indio_dev);
+
+	ret = of_property_read_u32(pdev->dev.of_node,
+				   "atmel,min-sample-rate-hz",
+				   &st->soc_info.min_sample_rate);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"invalid or missing value for atmel,min-sample-rate-hz\n");
+		return ret;
+	}
+
+	ret = of_property_read_u32(pdev->dev.of_node,
+				   "atmel,max-sample-rate-hz",
+				   &st->soc_info.max_sample_rate);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"invalid or missing value for atmel,max-sample-rate-hz\n");
+		return ret;
+	}
+
+	ret = of_property_read_u32(pdev->dev.of_node, "atmel,startup-time-ms",
+				   &st->soc_info.startup_time);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"invalid or missing value for atmel,startup-time-ms\n");
+		return ret;
+	}
+
+	init_waitqueue_head(&st->wq_data_available);
+	mutex_init(&st->lock);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -EINVAL;
+
+	st->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(st->base))
+		return PTR_ERR(st->base);
+
+	st->irq = platform_get_irq(pdev, 0);
+	if (st->irq <= 0) {
+		if (!st->irq)
+			st->irq = -ENXIO;
+
+		return st->irq;
+	}
+
+	st->per_clk = devm_clk_get(&pdev->dev, "adc_clk");
+	if (IS_ERR(st->per_clk))
+		return PTR_ERR(st->per_clk);
+
+	st->reg = devm_regulator_get(&pdev->dev, "vddana");
+	if (IS_ERR(st->reg))
+		return PTR_ERR(st->reg);
+
+	st->vref = devm_regulator_get(&pdev->dev, "vref");
+	if (IS_ERR(st->vref))
+		return PTR_ERR(st->vref);
+
+	ret = devm_request_irq(&pdev->dev, st->irq, at91_adc_interrupt, 0,
+			       pdev->dev.driver->name, indio_dev);
+	if (ret)
+		return ret;
+
+	ret = regulator_enable(st->reg);
+	if (ret)
+		return ret;
+
+	ret = regulator_enable(st->vref);
+	if (ret)
+		goto reg_disable;
+
+	st->vref_uv = regulator_get_voltage(st->vref);
+	if (st->vref_uv <= 0) {
+		ret = -EINVAL;
+		goto vref_disable;
+	}
+
+	at91_adc_writel(st, AT91_SAMA5D2_CR, AT91_SAMA5D2_CR_SWRST);
+	at91_adc_writel(st, AT91_SAMA5D2_IDR, 0xffffffff);
+
+	at91_adc_setup_samp_freq(st, st->soc_info.min_sample_rate);
+
+	ret = clk_prepare_enable(st->per_clk);
+	if (ret)
+		goto vref_disable;
+
+	ret = iio_device_register(indio_dev);
+	if (ret < 0)
+		goto per_clk_disable_unprepare;
+
+	dev_info(&pdev->dev, "version: %x\n",
+		 readl_relaxed(st->base + AT91_SAMA5D2_VERSION));
+
+	return 0;
+
+per_clk_disable_unprepare:
+	clk_disable_unprepare(st->per_clk);
+vref_disable:
+	regulator_disable(st->vref);
+reg_disable:
+	regulator_disable(st->reg);
+	return ret;
+}
+
+static int at91_adc_remove(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+	struct at91_adc_state *st = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+
+	clk_disable_unprepare(st->per_clk);
+
+	regulator_disable(st->vref);
+	regulator_disable(st->reg);
+
+	return 0;
+}
+
+static const struct of_device_id at91_adc_dt_match[] = {
+	{
+		.compatible = "atmel,sama5d2-adc",
+	}, {
+		/* sentinel */
+	}
+};
+MODULE_DEVICE_TABLE(of, at91_adc_dt_match);
+
+static struct platform_driver at91_adc_driver = {
+	.probe = at91_adc_probe,
+	.remove = at91_adc_remove,
+	.driver = {
+		.name = "at91-sama5d2_adc",
+		.of_match_table = at91_adc_dt_match,
+	},
+};
+module_platform_driver(at91_adc_driver)
+
+MODULE_AUTHOR("Ludovic Desroches <ludovic.desroches@atmel.com>");
+MODULE_DESCRIPTION("Atmel AT91 SAMA5D2 ADC");
+MODULE_LICENSE("GPL v2");