mfd: cpcap: Add minimal support

Many Motorola phones like droid 4 are using a custom PMIC called CPCAP
or 6556002. We can support it's core features quite easily with regmap_spi
and regmap_irq.

The children of cpcap, such as regulators, ADC and USB, can be just regular
device drivers and defined in the dts file. They get probed as we call
of_platform_populate() at the end of our probe, and then the children
can just call dev_get_regmap(dev.parent, NULL) to get the regmap.

Cc: devicetree@vger.kernel.org
Cc: Marcel Partap <mpartap@gmx.net>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Scott <michael.scott@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

Documentation/devicetree/bindings/mfd/motorola-cpcap.txt

+Motorola CPCAP PMIC device tree binding
+
+Required properties:
+- compatible		: One or both of "motorola,cpcap" or "ste,6556002"
+- reg			: SPI chip select
+- interrupt-parent	: The parent interrupt controller
+- interrupts		: The interrupt line the device is connected to
+- interrupt-controller	: Marks the device node as an interrupt controller
+- #interrupt-cells	: The number of cells to describe an IRQ, should be 2
+- #address-cells	: Child device offset number of cells, should be 1
+- #size-cells		: Child device size number of cells, should be 0
+- spi-max-frequency	: Typically set to 3000000
+- spi-cs-high		: SPI chip select direction
+
+Example:
+
+&mcspi1 {
+	cpcap: pmic@0 {
+		compatible = "motorola,cpcap", "ste,6556002";
+		reg = <0>;	/* cs0 */
+		interrupt-parent = <&gpio1>;
+		interrupts = <7 IRQ_TYPE_EDGE_RISING>;
+		interrupt-controller;
+		#interrupt-cells = <2>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		spi-max-frequency = <3000000>;
+		spi-cs-high;
+	};
+};
+

drivers/mfd/Kconfig

@@ -715,6 +715,17 @@ config EZX_PCAP
 	  This enables the PCAP ASIC present on EZX Phones. This is
 	  needed for MMC, TouchScreen, Sound, USB, etc..
 
+config MFD_CPCAP
+	tristate "Support for Motorola CPCAP"
+	depends on SPI
+	depends on OF || COMPILE_TEST
+	select REGMAP_SPI
+	select REGMAP_IRQ
+	help
+	  Say yes here if you want to include driver for CPCAP.
+	  It is used on many Motorola phones and tablets as a PMIC.
+	  At least Motorola Droid 4 is known to use CPCAP.
+
 config MFD_VIPERBOARD
         tristate "Nano River Technologies Viperboard"
 	select MFD_CORE

drivers/mfd/Makefile

@@ -97,6 +97,7 @@ obj-$(CONFIG_MFD_MC13XXX_I2C)	+= mc13xxx-i2c.o
 obj-$(CONFIG_MFD_CORE)		+= mfd-core.o
 
 obj-$(CONFIG_EZX_PCAP)		+= ezx-pcap.o
+obj-$(CONFIG_MFD_CPCAP)		+= motorola-cpcap.o
 
 obj-$(CONFIG_MCP)		+= mcp-core.o
 obj-$(CONFIG_MCP_SA11X0)	+= mcp-sa11x0.o

drivers/mfd/motorola-cpcap.c

+/*
+ * Motorola CPCAP PMIC core driver
+ *
+ * Copyright (C) 2016 Tony Lindgren <tony@atomide.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/device.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/regmap.h>
+#include <linux/sysfs.h>
+
+#include <linux/mfd/motorola-cpcap.h>
+#include <linux/spi/spi.h>
+
+#define CPCAP_NR_IRQ_REG_BANKS	6
+#define CPCAP_NR_IRQ_CHIPS	3
+
+struct cpcap_ddata {
+	struct spi_device *spi;
+	struct regmap_irq *irqs;
+	struct regmap_irq_chip_data *irqdata[CPCAP_NR_IRQ_CHIPS];
+	const struct regmap_config *regmap_conf;
+	struct regmap *regmap;
+};
+
+static int cpcap_check_revision(struct cpcap_ddata *cpcap)
+{
+	u16 vendor, rev;
+	int ret;
+
+	ret = cpcap_get_vendor(&cpcap->spi->dev, cpcap->regmap, &vendor);
+	if (ret)
+		return ret;
+
+	ret = cpcap_get_revision(&cpcap->spi->dev, cpcap->regmap, &rev);
+	if (ret)
+		return ret;
+
+	dev_info(&cpcap->spi->dev, "CPCAP vendor: %s rev: %i.%i (%x)\n",
+		 vendor == CPCAP_VENDOR_ST ? "ST" : "TI",
+		 CPCAP_REVISION_MAJOR(rev), CPCAP_REVISION_MINOR(rev),
+		 rev);
+
+	if (rev < CPCAP_REVISION_2_1) {
+		dev_info(&cpcap->spi->dev,
+			 "Please add old CPCAP revision support as needed\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+/*
+ * First two irq chips are the two private macro interrupt chips, the third
+ * irq chip is for register banks 1 - 4 and is available for drivers to use.
+ */
+static struct regmap_irq_chip cpcap_irq_chip[CPCAP_NR_IRQ_CHIPS] = {
+	{
+		.name = "cpcap-m2",
+		.num_regs = 1,
+		.status_base = CPCAP_REG_MI1,
+		.ack_base = CPCAP_REG_MI1,
+		.mask_base = CPCAP_REG_MIM1,
+		.use_ack = true,
+	},
+	{
+		.name = "cpcap-m2",
+		.num_regs = 1,
+		.status_base = CPCAP_REG_MI2,
+		.ack_base = CPCAP_REG_MI2,
+		.mask_base = CPCAP_REG_MIM2,
+		.use_ack = true,
+	},
+	{
+		.name = "cpcap1-4",
+		.num_regs = 4,
+		.status_base = CPCAP_REG_INT1,
+		.ack_base = CPCAP_REG_INT1,
+		.mask_base = CPCAP_REG_INTM1,
+		.type_base = CPCAP_REG_INTS1,
+		.use_ack = true,
+	},
+};
+
+static void cpcap_init_one_regmap_irq(struct cpcap_ddata *cpcap,
+				      struct regmap_irq *rirq,
+				      int irq_base, int irq)
+{
+	unsigned int reg_offset;
+	unsigned int bit, mask;
+
+	reg_offset = irq - irq_base;
+	reg_offset /= cpcap->regmap_conf->val_bits;
+	reg_offset *= cpcap->regmap_conf->reg_stride;
+
+	bit = irq % cpcap->regmap_conf->val_bits;
+	mask = (1 << bit);
+
+	rirq->reg_offset = reg_offset;
+	rirq->mask = mask;
+}
+
+static int cpcap_init_irq_chip(struct cpcap_ddata *cpcap, int irq_chip,
+			       int irq_start, int nr_irqs)
+{
+	struct regmap_irq_chip *chip = &cpcap_irq_chip[irq_chip];
+	int i, ret;
+
+	for (i = irq_start; i < irq_start + nr_irqs; i++) {
+		struct regmap_irq *rirq = &cpcap->irqs[i];
+
+		cpcap_init_one_regmap_irq(cpcap, rirq, irq_start, i);
+	}
+	chip->irqs = &cpcap->irqs[irq_start];
+	chip->num_irqs = nr_irqs;
+	chip->irq_drv_data = cpcap;
+
+	ret = devm_regmap_add_irq_chip(&cpcap->spi->dev, cpcap->regmap,
+				       cpcap->spi->irq,
+				       IRQF_TRIGGER_RISING |
+				       IRQF_SHARED, -1,
+				       chip, &cpcap->irqdata[irq_chip]);
+	if (ret) {
+		dev_err(&cpcap->spi->dev, "could not add irq chip %i: %i\n",
+			irq_chip, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int cpcap_init_irq(struct cpcap_ddata *cpcap)
+{
+	int ret;
+
+	cpcap->irqs = devm_kzalloc(&cpcap->spi->dev,
+				   sizeof(*cpcap->irqs) *
+				   CPCAP_NR_IRQ_REG_BANKS *
+				   cpcap->regmap_conf->val_bits,
+				   GFP_KERNEL);
+	if (!cpcap->irqs)
+		return -ENOMEM;
+
+	ret = cpcap_init_irq_chip(cpcap, 0, 0, 16);
+	if (ret)
+		return ret;
+
+	ret = cpcap_init_irq_chip(cpcap, 1, 16, 16);
+	if (ret)
+		return ret;
+
+	ret = cpcap_init_irq_chip(cpcap, 2, 32, 64);
+	if (ret)
+		return ret;
+
+	enable_irq_wake(cpcap->spi->irq);
+
+	return 0;
+}
+
+static const struct of_device_id cpcap_of_match[] = {
+	{ .compatible = "motorola,cpcap", },
+	{ .compatible = "st,6556002", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, cpcap_of_match);
+
+static const struct regmap_config cpcap_regmap_config = {
+	.reg_bits = 16,
+	.reg_stride = 4,
+	.pad_bits = 0,
+	.val_bits = 16,
+	.write_flag_mask = 0x8000,
+	.max_register = CPCAP_REG_ST_TEST2,
+	.cache_type = REGCACHE_NONE,
+	.reg_format_endian = REGMAP_ENDIAN_LITTLE,
+	.val_format_endian = REGMAP_ENDIAN_LITTLE,
+};
+
+static int cpcap_probe(struct spi_device *spi)
+{
+	const struct of_device_id *match;
+	struct cpcap_ddata *cpcap;
+	int ret;
+
+	match = of_match_device(of_match_ptr(cpcap_of_match), &spi->dev);
+	if (!match)
+		return -ENODEV;
+
+	cpcap = devm_kzalloc(&spi->dev, sizeof(*cpcap), GFP_KERNEL);
+	if (!cpcap)
+		return -ENOMEM;
+
+	cpcap->spi = spi;
+	spi_set_drvdata(spi, cpcap);
+
+	spi->bits_per_word = 16;
+	spi->mode = SPI_MODE_0 | SPI_CS_HIGH;
+
+	ret = spi_setup(spi);
+	if (ret)
+		return ret;
+
+	cpcap->regmap_conf = &cpcap_regmap_config;
+	cpcap->regmap = devm_regmap_init_spi(spi, &cpcap_regmap_config);
+	if (IS_ERR(cpcap->regmap)) {
+		ret = PTR_ERR(cpcap->regmap);
+		dev_err(&cpcap->spi->dev, "Failed to initialize regmap: %d\n",
+			ret);
+
+		return ret;
+	}
+
+	ret = cpcap_check_revision(cpcap);
+	if (ret) {
+		dev_err(&cpcap->spi->dev, "Failed to detect CPCAP: %i\n", ret);
+		return ret;
+	}
+
+	ret = cpcap_init_irq(cpcap);
+	if (ret)
+		return ret;
+
+	return of_platform_populate(spi->dev.of_node, NULL, NULL,
+				    &cpcap->spi->dev);
+}
+
+static int cpcap_remove(struct spi_device *pdev)
+{
+	struct cpcap_ddata *cpcap = spi_get_drvdata(pdev);
+
+	of_platform_depopulate(&cpcap->spi->dev);
+
+	return 0;
+}
+
+static struct spi_driver cpcap_driver = {
+	.driver = {
+		.name = "cpcap-core",
+		.of_match_table = cpcap_of_match,
+	},
+	.probe = cpcap_probe,
+	.remove = cpcap_remove,
+};
+module_spi_driver(cpcap_driver);
+
+MODULE_ALIAS("platform:cpcap");
+MODULE_DESCRIPTION("CPCAP driver");
+MODULE_AUTHOR("Tony Lindgren <tony@atomide.com>");
+MODULE_LICENSE("GPL v2");