mfd: Add support for Allwinner SoCs ADC

The Allwinner SoCs all have an ADC that can also act as a touchscreen
controller and a thermal sensor. For now, only the ADC and the thermal
sensor drivers are probed by the MFD, the touchscreen controller support
will be added later.

Signed-off-by: Quentin Schulz <quentin.schulz@free-electrons.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/Kconfig

@@ -40,6 +40,21 @@ config MFD_ACT8945A
 	  linear regulators, along with a complete ActivePath battery
 	  charger.
 
+config MFD_SUN4I_GPADC
+	tristate "Allwinner sunxi platforms' GPADC MFD driver"
+	select MFD_CORE
+	select REGMAP_MMIO
+	depends on ARCH_SUNXI || COMPILE_TEST
+	help
+	  Select this to get support for Allwinner SoCs (A10, A13 and A31) ADC.
+	  This driver will only map the hardware interrupt and registers, you
+	  have to select individual drivers based on this MFD to be able to use
+	  the ADC or the thermal sensor. This will try to probe the ADC driver
+	  sun4i-gpadc-iio and the hwmon driver iio_hwmon.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called sun4i-gpadc.
+
 config MFD_AS3711
 	bool "AMS AS3711"
 	select MFD_CORE

drivers/mfd/Makefile

@@ -211,3 +211,4 @@ obj-$(CONFIG_INTEL_SOC_PMIC)	+= intel-soc-pmic.o
 obj-$(CONFIG_MFD_MT6397)	+= mt6397-core.o
 
 obj-$(CONFIG_MFD_ALTERA_A10SR)	+= altera-a10sr.o
+obj-$(CONFIG_MFD_SUN4I_GPADC)	+= sun4i-gpadc.o

drivers/mfd/sun4i-gpadc.c

@@ -0,0 +1,181 @@
+/* ADC MFD core driver for sunxi platforms
+ *
+ * Copyright (c) 2016 Quentin Schulz <quentin.schulz@free-electrons.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.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/of_irq.h>
+#include <linux/regmap.h>
+
+#include <linux/mfd/sun4i-gpadc.h>
+
+#define ARCH_SUN4I_A10 0
+#define ARCH_SUN5I_A13 1
+#define ARCH_SUN6I_A31 2
+
+static struct resource adc_resources[] = {
+	DEFINE_RES_IRQ_NAMED(SUN4I_GPADC_IRQ_FIFO_DATA, "FIFO_DATA_PENDING"),
+	DEFINE_RES_IRQ_NAMED(SUN4I_GPADC_IRQ_TEMP_DATA, "TEMP_DATA_PENDING"),
+};
+
+static const struct regmap_irq sun4i_gpadc_regmap_irq[] = {
+	REGMAP_IRQ_REG(SUN4I_GPADC_IRQ_FIFO_DATA, 0,
+		       SUN4I_GPADC_INT_FIFOC_TP_DATA_IRQ_EN),
+	REGMAP_IRQ_REG(SUN4I_GPADC_IRQ_TEMP_DATA, 0,
+		       SUN4I_GPADC_INT_FIFOC_TEMP_IRQ_EN),
+};
+
+static const struct regmap_irq_chip sun4i_gpadc_regmap_irq_chip = {
+	.name = "sun4i_gpadc_irq_chip",
+	.status_base = SUN4I_GPADC_INT_FIFOS,
+	.ack_base = SUN4I_GPADC_INT_FIFOS,
+	.mask_base = SUN4I_GPADC_INT_FIFOC,
+	.init_ack_masked = true,
+	.mask_invert = true,
+	.irqs = sun4i_gpadc_regmap_irq,
+	.num_irqs = ARRAY_SIZE(sun4i_gpadc_regmap_irq),
+	.num_regs = 1,
+};
+
+static struct mfd_cell sun4i_gpadc_cells[] = {
+	{
+		.name	= "sun4i-a10-gpadc-iio",
+		.resources = adc_resources,
+		.num_resources = ARRAY_SIZE(adc_resources),
+	},
+	{ .name = "iio_hwmon" }
+};
+
+static struct mfd_cell sun5i_gpadc_cells[] = {
+	{
+		.name	= "sun5i-a13-gpadc-iio",
+		.resources = adc_resources,
+		.num_resources = ARRAY_SIZE(adc_resources),
+	},
+	{ .name = "iio_hwmon" },
+};
+
+static struct mfd_cell sun6i_gpadc_cells[] = {
+	{
+		.name	= "sun6i-a31-gpadc-iio",
+		.resources = adc_resources,
+		.num_resources = ARRAY_SIZE(adc_resources),
+	},
+	{ .name = "iio_hwmon" },
+};
+
+static const struct regmap_config sun4i_gpadc_regmap_config = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = 4,
+	.fast_io = true,
+};
+
+static const struct of_device_id sun4i_gpadc_of_match[] = {
+	{
+		.compatible = "allwinner,sun4i-a10-ts",
+		.data = (void *)ARCH_SUN4I_A10,
+	}, {
+		.compatible = "allwinner,sun5i-a13-ts",
+		.data = (void *)ARCH_SUN5I_A13,
+	}, {
+		.compatible = "allwinner,sun6i-a31-ts",
+		.data = (void *)ARCH_SUN6I_A31,
+	}, { /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(of, sun4i_gpadc_of_match);
+
+static int sun4i_gpadc_probe(struct platform_device *pdev)
+{
+	struct sun4i_gpadc_dev *dev;
+	struct resource *mem;
+	const struct of_device_id *of_id;
+	const struct mfd_cell *cells;
+	unsigned int irq, size;
+	int ret;
+
+	of_id = of_match_node(sun4i_gpadc_of_match, pdev->dev.of_node);
+	if (!of_id)
+		return -EINVAL;
+
+	switch ((int)of_id->data) {
+	case ARCH_SUN4I_A10:
+		cells = sun4i_gpadc_cells;
+		size = ARRAY_SIZE(sun4i_gpadc_cells);
+		break;
+	case ARCH_SUN5I_A13:
+		cells = sun5i_gpadc_cells;
+		size = ARRAY_SIZE(sun5i_gpadc_cells);
+		break;
+	case ARCH_SUN6I_A31:
+		cells = sun6i_gpadc_cells;
+		size = ARRAY_SIZE(sun6i_gpadc_cells);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return -ENOMEM;
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	dev->base = devm_ioremap_resource(&pdev->dev, mem);
+	if (IS_ERR(dev->base))
+		return PTR_ERR(dev->base);
+
+	dev->dev = &pdev->dev;
+	dev_set_drvdata(dev->dev, dev);
+
+	dev->regmap = devm_regmap_init_mmio(dev->dev, dev->base,
+					    &sun4i_gpadc_regmap_config);
+	if (IS_ERR(dev->regmap)) {
+		ret = PTR_ERR(dev->regmap);
+		dev_err(&pdev->dev, "failed to init regmap: %d\n", ret);
+		return ret;
+	}
+
+	/* Disable all interrupts */
+	regmap_write(dev->regmap, SUN4I_GPADC_INT_FIFOC, 0);
+
+	irq = platform_get_irq(pdev, 0);
+	ret = devm_regmap_add_irq_chip(&pdev->dev, dev->regmap, irq,
+				       IRQF_ONESHOT, 0,
+				       &sun4i_gpadc_regmap_irq_chip,
+				       &dev->regmap_irqc);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to add irq chip: %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_mfd_add_devices(dev->dev, 0, cells, size, NULL, 0, NULL);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to add MFD devices: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static struct platform_driver sun4i_gpadc_driver = {
+	.driver = {
+		.name = "sun4i-gpadc",
+		.of_match_table = of_match_ptr(sun4i_gpadc_of_match),
+	},
+	.probe = sun4i_gpadc_probe,
+};
+
+module_platform_driver(sun4i_gpadc_driver);
+
+MODULE_DESCRIPTION("Allwinner sunxi platforms' GPADC MFD core driver");
+MODULE_AUTHOR("Quentin Schulz <quentin.schulz@free-electrons.com>");
+MODULE_LICENSE("GPL v2");