staging:iio:adc:spear Move out of staging.

There are some unanswered questions due to disagreements between the code
and various datasheets (including between different datasheets for the same
part).

I don't think that is necessarily a reason to keep it in staging however.
I'm partly posting this patch inorder to reignite debate and with a bit
of luck find someone who has one of these to test!

Signed-off-by: Jonathan Cameron <jic23@kernel.org>

3 files changed, 407 insertions, 0 deletions

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index dedae7a..789a5fb 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -494,6 +494,17 @@ config ROCKCHIP_SARADC
 	  To compile this driver as a module, choose M here: the
 	  module will be called rockchip_saradc.
 
+config SPEAR_ADC
+	tristate "ST SPEAr ADC"
+	depends on PLAT_SPEAR || COMPILE_TEST
+	depends on HAS_IOMEM
+	help
+	  Say yes here to build support for the integrated ADC inside the
+	  ST SPEAr SoC. Provides direct access via sysfs.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called spear_adc.
+
 config STM32_ADC_CORE
 	tristate "STMicroelectronics STM32 adc core"
 	depends on ARCH_STM32 || COMPILE_TEST
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index d001262..19e48af 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -46,6 +46,7 @@ obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
 obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-spmi-vadc.o
 obj-$(CONFIG_RCAR_GYRO_ADC) += rcar-gyroadc.o
 obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
+obj-$(CONFIG_SPEAR_ADC) += spear_adc.o
 obj-$(CONFIG_STX104) += stx104.o
 obj-$(CONFIG_STM32_ADC_CORE) += stm32-adc-core.o
 obj-$(CONFIG_STM32_ADC) += stm32-adc.o
diff --git a/drivers/iio/adc/spear_adc.c b/drivers/iio/adc/spear_adc.c
new file mode 100644
index 0000000..5dd61f6
--- /dev/null
+++ b/drivers/iio/adc/spear_adc.c
@@ -0,0 +1,395 @@
+/*
+ * ST SPEAr ADC driver
+ *
+ * Copyright 2012 Stefan Roese <sr@denx.de>
+ *
+ * Licensed under the GPL-2.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/completion.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+/* SPEAR registers definitions */
+#define SPEAR600_ADC_SCAN_RATE_LO(x)	((x) & 0xFFFF)
+#define SPEAR600_ADC_SCAN_RATE_HI(x)	(((x) >> 0x10) & 0xFFFF)
+#define SPEAR_ADC_CLK_LOW(x)		(((x) & 0xf) << 0)
+#define SPEAR_ADC_CLK_HIGH(x)		(((x) & 0xf) << 4)
+
+/* Bit definitions for SPEAR_ADC_STATUS */
+#define SPEAR_ADC_STATUS_START_CONVERSION	BIT(0)
+#define SPEAR_ADC_STATUS_CHANNEL_NUM(x)		((x) << 1)
+#define SPEAR_ADC_STATUS_ADC_ENABLE		BIT(4)
+#define SPEAR_ADC_STATUS_AVG_SAMPLE(x)		((x) << 5)
+#define SPEAR_ADC_STATUS_VREF_INTERNAL		BIT(9)
+
+#define SPEAR_ADC_DATA_MASK		0x03ff
+#define SPEAR_ADC_DATA_BITS		10
+
+#define SPEAR_ADC_MOD_NAME "spear-adc"
+
+#define SPEAR_ADC_CHANNEL_NUM		8
+
+#define SPEAR_ADC_CLK_MIN			2500000
+#define SPEAR_ADC_CLK_MAX			20000000
+
+struct adc_regs_spear3xx {
+	u32 status;
+	u32 average;
+	u32 scan_rate;
+	u32 clk;	/* Not avail for 1340 & 1310 */
+	u32 ch_ctrl[SPEAR_ADC_CHANNEL_NUM];
+	u32 ch_data[SPEAR_ADC_CHANNEL_NUM];
+};
+
+struct chan_data {
+	u32 lsb;
+	u32 msb;
+};
+
+struct adc_regs_spear6xx {
+	u32 status;
+	u32 pad[2];
+	u32 clk;
+	u32 ch_ctrl[SPEAR_ADC_CHANNEL_NUM];
+	struct chan_data ch_data[SPEAR_ADC_CHANNEL_NUM];
+	u32 scan_rate_lo;
+	u32 scan_rate_hi;
+	struct chan_data average;
+};
+
+struct spear_adc_state {
+	struct device_node *np;
+	struct adc_regs_spear3xx __iomem *adc_base_spear3xx;
+	struct adc_regs_spear6xx __iomem *adc_base_spear6xx;
+	struct clk *clk;
+	struct completion completion;
+	u32 current_clk;
+	u32 sampling_freq;
+	u32 avg_samples;
+	u32 vref_external;
+	u32 value;
+};
+
+/*
+ * Functions to access some SPEAr ADC register. Abstracted into
+ * static inline functions, because of different register offsets
+ * on different SoC variants (SPEAr300 vs SPEAr600 etc).
+ */
+static void spear_adc_set_status(struct spear_adc_state *st, u32 val)
+{
+	__raw_writel(val, &st->adc_base_spear6xx->status);
+}
+
+static void spear_adc_set_clk(struct spear_adc_state *st, u32 val)
+{
+	u32 clk_high, clk_low, count;
+	u32 apb_clk = clk_get_rate(st->clk);
+
+	count = DIV_ROUND_UP(apb_clk, val);
+	clk_low = count / 2;
+	clk_high = count - clk_low;
+	st->current_clk = apb_clk / count;
+
+	__raw_writel(SPEAR_ADC_CLK_LOW(clk_low) | SPEAR_ADC_CLK_HIGH(clk_high),
+		     &st->adc_base_spear6xx->clk);
+}
+
+static void spear_adc_set_ctrl(struct spear_adc_state *st, int n,
+			       u32 val)
+{
+	__raw_writel(val, &st->adc_base_spear6xx->ch_ctrl[n]);
+}
+
+static u32 spear_adc_get_average(struct spear_adc_state *st)
+{
+	if (of_device_is_compatible(st->np, "st,spear600-adc")) {
+		return __raw_readl(&st->adc_base_spear6xx->average.msb) &
+			SPEAR_ADC_DATA_MASK;
+	} else {
+		return __raw_readl(&st->adc_base_spear3xx->average) &
+			SPEAR_ADC_DATA_MASK;
+	}
+}
+
+static void spear_adc_set_scanrate(struct spear_adc_state *st, u32 rate)
+{
+	if (of_device_is_compatible(st->np, "st,spear600-adc")) {
+		__raw_writel(SPEAR600_ADC_SCAN_RATE_LO(rate),
+			     &st->adc_base_spear6xx->scan_rate_lo);
+		__raw_writel(SPEAR600_ADC_SCAN_RATE_HI(rate),
+			     &st->adc_base_spear6xx->scan_rate_hi);
+	} else {
+		__raw_writel(rate, &st->adc_base_spear3xx->scan_rate);
+	}
+}
+
+static int spear_adc_read_raw(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan,
+			      int *val,
+			      int *val2,
+			      long mask)
+{
+	struct spear_adc_state *st = iio_priv(indio_dev);
+	u32 status;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&indio_dev->mlock);
+
+		status = SPEAR_ADC_STATUS_CHANNEL_NUM(chan->channel) |
+			SPEAR_ADC_STATUS_AVG_SAMPLE(st->avg_samples) |
+			SPEAR_ADC_STATUS_START_CONVERSION |
+			SPEAR_ADC_STATUS_ADC_ENABLE;
+		if (st->vref_external == 0)
+			status |= SPEAR_ADC_STATUS_VREF_INTERNAL;
+
+		spear_adc_set_status(st, status);
+		wait_for_completion(&st->completion); /* set by ISR */
+		*val = st->value;
+
+		mutex_unlock(&indio_dev->mlock);
+
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_SCALE:
+		*val = st->vref_external;
+		*val2 = SPEAR_ADC_DATA_BITS;
+		return IIO_VAL_FRACTIONAL_LOG2;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*val = st->current_clk;
+		return IIO_VAL_INT;
+	}
+
+	return -EINVAL;
+}
+
+static int spear_adc_write_raw(struct iio_dev *indio_dev,
+			       struct iio_chan_spec const *chan,
+			       int val,
+			       int val2,
+			       long mask)
+{
+	struct spear_adc_state *st = iio_priv(indio_dev);
+	int ret = 0;
+
+	if (mask != IIO_CHAN_INFO_SAMP_FREQ)
+		return -EINVAL;
+
+	mutex_lock(&indio_dev->mlock);
+
+	if ((val < SPEAR_ADC_CLK_MIN) ||
+	    (val > SPEAR_ADC_CLK_MAX) ||
+	    (val2 != 0)) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	spear_adc_set_clk(st, val);
+
+out:
+	mutex_unlock(&indio_dev->mlock);
+	return ret;
+}
+
+#define SPEAR_ADC_CHAN(idx) {				\
+	.type = IIO_VOLTAGE,				\
+	.indexed = 1,					\
+	.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),\
+	.channel = idx,					\
+}
+
+static const struct iio_chan_spec spear_adc_iio_channels[] = {
+	SPEAR_ADC_CHAN(0),
+	SPEAR_ADC_CHAN(1),
+	SPEAR_ADC_CHAN(2),
+	SPEAR_ADC_CHAN(3),
+	SPEAR_ADC_CHAN(4),
+	SPEAR_ADC_CHAN(5),
+	SPEAR_ADC_CHAN(6),
+	SPEAR_ADC_CHAN(7),
+};
+
+static irqreturn_t spear_adc_isr(int irq, void *dev_id)
+{
+	struct spear_adc_state *st = dev_id;
+
+	/* Read value to clear IRQ */
+	st->value = spear_adc_get_average(st);
+	complete(&st->completion);
+
+	return IRQ_HANDLED;
+}
+
+static int spear_adc_configure(struct spear_adc_state *st)
+{
+	int i;
+
+	/* Reset ADC core */
+	spear_adc_set_status(st, 0);
+	__raw_writel(0, &st->adc_base_spear6xx->clk);
+	for (i = 0; i < 8; i++)
+		spear_adc_set_ctrl(st, i, 0);
+	spear_adc_set_scanrate(st, 0);
+
+	spear_adc_set_clk(st, st->sampling_freq);
+
+	return 0;
+}
+
+static const struct iio_info spear_adc_info = {
+	.read_raw = &spear_adc_read_raw,
+	.write_raw = &spear_adc_write_raw,
+	.driver_module = THIS_MODULE,
+};
+
+static int spear_adc_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct device *dev = &pdev->dev;
+	struct spear_adc_state *st;
+	struct resource *res;
+	struct iio_dev *indio_dev = NULL;
+	int ret = -ENODEV;
+	int irq;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(struct spear_adc_state));
+	if (!indio_dev) {
+		dev_err(dev, "failed allocating iio device\n");
+		return -ENOMEM;
+	}
+
+	st = iio_priv(indio_dev);
+	st->np = np;
+
+	/*
+	 * SPEAr600 has a different register layout than other SPEAr SoC's
+	 * (e.g. SPEAr3xx). Let's provide two register base addresses
+	 * to support multi-arch kernels.
+	 */
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	st->adc_base_spear6xx = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(st->adc_base_spear6xx))
+		return PTR_ERR(st->adc_base_spear6xx);
+
+	st->adc_base_spear3xx =
+		(struct adc_regs_spear3xx __iomem *)st->adc_base_spear6xx;
+
+	st->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(st->clk)) {
+		dev_err(dev, "failed getting clock\n");
+		return PTR_ERR(st->clk);
+	}
+
+	ret = clk_prepare_enable(st->clk);
+	if (ret) {
+		dev_err(dev, "failed enabling clock\n");
+		return ret;
+	}
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq <= 0) {
+		dev_err(dev, "failed getting interrupt resource\n");
+		ret = -EINVAL;
+		goto errout2;
+	}
+
+	ret = devm_request_irq(dev, irq, spear_adc_isr, 0, SPEAR_ADC_MOD_NAME,
+			       st);
+	if (ret < 0) {
+		dev_err(dev, "failed requesting interrupt\n");
+		goto errout2;
+	}
+
+	if (of_property_read_u32(np, "sampling-frequency",
+				 &st->sampling_freq)) {
+		dev_err(dev, "sampling-frequency missing in DT\n");
+		ret = -EINVAL;
+		goto errout2;
+	}
+
+	/*
+	 * Optional avg_samples defaults to 0, resulting in single data
+	 * conversion
+	 */
+	of_property_read_u32(np, "average-samples", &st->avg_samples);
+
+	/*
+	 * Optional vref_external defaults to 0, resulting in internal vref
+	 * selection
+	 */
+	of_property_read_u32(np, "vref-external", &st->vref_external);
+
+	spear_adc_configure(st);
+
+	platform_set_drvdata(pdev, indio_dev);
+
+	init_completion(&st->completion);
+
+	indio_dev->name = SPEAR_ADC_MOD_NAME;
+	indio_dev->dev.parent = dev;
+	indio_dev->info = &spear_adc_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = spear_adc_iio_channels;
+	indio_dev->num_channels = ARRAY_SIZE(spear_adc_iio_channels);
+
+	ret = iio_device_register(indio_dev);
+	if (ret)
+		goto errout2;
+
+	dev_info(dev, "SPEAR ADC driver loaded, IRQ %d\n", irq);
+
+	return 0;
+
+errout2:
+	clk_disable_unprepare(st->clk);
+	return ret;
+}
+
+static int spear_adc_remove(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+	struct spear_adc_state *st = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+	clk_disable_unprepare(st->clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id spear_adc_dt_ids[] = {
+	{ .compatible = "st,spear600-adc", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, spear_adc_dt_ids);
+#endif
+
+static struct platform_driver spear_adc_driver = {
+	.probe		= spear_adc_probe,
+	.remove		= spear_adc_remove,
+	.driver		= {
+		.name	= SPEAR_ADC_MOD_NAME,
+		.of_match_table = of_match_ptr(spear_adc_dt_ids),
+	},
+};
+
+module_platform_driver(spear_adc_driver);
+
+MODULE_AUTHOR("Stefan Roese <sr@denx.de>");
+MODULE_DESCRIPTION("SPEAr ADC driver");
+MODULE_LICENSE("GPL");