gpio: Add Intel WhiskeyCove PMIC GPIO driver

This patch introduces a separate GPIO driver for Intel WhiskeyCove PMIC.
This driver is based on gpio-crystalcove.c.

Changes in v7:
 - Fixed various coding style comments from Andy Shevchenko
Changes in v6:
 - Removed unnecessary wcove_gpio_remove()
 - Used devm_gpiochip_remove() instead of gpiochip_remove()
 - Various coding style changes per Mika's comment
Changes in v5:
 - Revisited the interrupt handler code to iterate until all pending
   interrupts are handled. This change is to avoid missing interrupt
   when we're inside the interrupt handler.
 - Used regmap_bulk_read() to read address adjacent registers.
Changes in v4:
 - Converted CTLI_INTCNT_XX macros to less verbose ones INT_DETECT_XX.
 - Add comments about why there is no .pm for the driver.
 - Header files re-ordered.
 - Various coding style change to address Andy's comments.
Changes in v3:
 - Fixed the year in copyright line(2015-->2016).
 - Removed DRV_NAME macro.
 - Added kernel-doc for regmap_irq_chip of the wcove_gpio structure.
 - Line length fix.
Changes in v2:
 - Typo fix (Whsikey --> Whiskey).
 - Included linux/gpio/driver.h instead of linux/gpio.h
 - Implemented .set_single_ended().
 - Added GPIO register description.
 - Replaced container_of() with gpiochip_get_data().
 - Removed unnecessary "if (gpio > WCOVE_VGPIO_NUM" check.
 - Removed the device id table and added MODULE_ALIAS().

Signed-off-by: Ajay Thomas <ajay.thomas.david.rajamanickam@intel.com>
Signed-off-by: Bin Gao <bin.gao@intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

3 files changed, 469 insertions, 0 deletions

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index ed968d112399..591f692dae63 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -969,6 +969,19 @@ config GPIO_UCB1400
 	  This enables support for the Philips UCB1400 GPIO pins.
 	  The UCB1400 is an AC97 audio codec.
 
+config GPIO_WHISKEY_COVE
+	tristate "GPIO support for Whiskey Cove PMIC"
+	depends on INTEL_SOC_PMIC
+	select GPIOLIB_IRQCHIP
+	help
+	  Support for GPIO pins on Whiskey Cove PMIC.
+
+	  Say Yes if you have a Intel SoC based tablet with Whiskey Cove PMIC
+	  inside.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called gpio-wcove.
+
 config GPIO_WM831X
 	tristate "WM831x GPIOs"
 	depends on MFD_WM831X
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index b7d509e27ed1..031195cdde7f 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -121,6 +121,7 @@ obj-$(CONFIG_GPIO_VF610)	+= gpio-vf610.o
 obj-$(CONFIG_GPIO_VIPERBOARD)	+= gpio-viperboard.o
 obj-$(CONFIG_GPIO_VR41XX)	+= gpio-vr41xx.o
 obj-$(CONFIG_GPIO_VX855)	+= gpio-vx855.o
+obj-$(CONFIG_GPIO_WHISKEY_COVE)	+= gpio-wcove.o
 obj-$(CONFIG_GPIO_WM831X)	+= gpio-wm831x.o
 obj-$(CONFIG_GPIO_WM8350)	+= gpio-wm8350.o
 obj-$(CONFIG_GPIO_WM8994)	+= gpio-wm8994.o
diff --git a/drivers/gpio/gpio-wcove.c b/drivers/gpio/gpio-wcove.c
new file mode 100644
index 000000000000..f5c88df96eaa
--- /dev/null
+++ b/drivers/gpio/gpio-wcove.c
@@ -0,0 +1,455 @@
+/*
+ * Intel Whiskey Cove PMIC GPIO Driver
+ *
+ * This driver is written based on gpio-crystalcove.c
+ *
+ * Copyright (C) 2016 Intel Corporation. All rights reserved.
+ *
+ * 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.
+ *
+ * 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/interrupt.h>
+#include <linux/gpio/driver.h>
+#include <linux/mfd/intel_soc_pmic.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/seq_file.h>
+
+/*
+ * Whiskey Cove PMIC has 13 physical GPIO pins divided into 3 banks:
+ * Bank 0: Pin 0 - 6
+ * Bank 1: Pin 7 - 10
+ * Bank 2: Pin 11 -12
+ * Each pin has one output control register and one input control register.
+ */
+#define BANK0_NR_PINS		7
+#define BANK1_NR_PINS		4
+#define BANK2_NR_PINS		2
+#define WCOVE_GPIO_NUM		(BANK0_NR_PINS + BANK1_NR_PINS + BANK2_NR_PINS)
+#define WCOVE_VGPIO_NUM		94
+/* GPIO output control registers (one per pin): 0x4e44 - 0x4e50 */
+#define GPIO_OUT_CTRL_BASE	0x4e44
+/* GPIO input control registers (one per pin): 0x4e51 - 0x4e5d */
+#define GPIO_IN_CTRL_BASE	0x4e51
+
+/*
+ * GPIO interrupts are organized in two groups:
+ * Group 0: Bank 0 pins (Pin 0 - 6)
+ * Group 1: Bank 1 and Bank 2 pins (Pin 7 - 12)
+ * Each group has two registers (one bit per pin): status and mask.
+ */
+#define GROUP0_NR_IRQS		7
+#define GROUP1_NR_IRQS		6
+#define IRQ_MASK_BASE		0x4e19
+#define IRQ_STATUS_BASE		0x4e0b
+#define UPDATE_IRQ_TYPE		BIT(0)
+#define UPDATE_IRQ_MASK		BIT(1)
+
+#define CTLI_INTCNT_DIS		(0 << 1)
+#define CTLI_INTCNT_NE		(1 << 1)
+#define CTLI_INTCNT_PE		(2 << 1)
+#define CTLI_INTCNT_BE		(3 << 1)
+
+#define CTLO_DIR_IN		(0 << 5)
+#define CTLO_DIR_OUT		(1 << 5)
+
+#define CTLO_DRV_MASK		(1 << 4)
+#define CTLO_DRV_OD		(0 << 4)
+#define CTLO_DRV_CMOS		(1 << 4)
+
+#define CTLO_DRV_REN		(1 << 3)
+
+#define CTLO_RVAL_2KDOWN	(0 << 1)
+#define CTLO_RVAL_2KUP		(1 << 1)
+#define CTLO_RVAL_50KDOWN	(2 << 1)
+#define CTLO_RVAL_50KUP		(3 << 1)
+
+#define CTLO_INPUT_SET	(CTLO_DRV_CMOS | CTLO_DRV_REN | CTLO_RVAL_2KUP)
+#define CTLO_OUTPUT_SET	(CTLO_DIR_OUT | CTLO_INPUT_SET)
+
+enum ctrl_register {
+	CTRL_IN,
+	CTRL_OUT,
+};
+
+/*
+ * struct wcove_gpio - Whiskey Cove GPIO controller
+ * @buslock: for bus lock/sync and unlock.
+ * @chip: the abstract gpio_chip structure.
+ * @dev: the gpio device
+ * @regmap: the regmap from the parent device.
+ * @regmap_irq_chip: the regmap of the gpio irq chip.
+ * @update: pending IRQ setting update, to be written to the chip upon unlock.
+ * @intcnt: the Interrupt Detect value to be written.
+ * @set_irq_mask: true if the IRQ mask needs to be set, false to clear.
+ */
+struct wcove_gpio {
+	struct mutex buslock;
+	struct gpio_chip chip;
+	struct device *dev;
+	struct regmap *regmap;
+	struct regmap_irq_chip_data *regmap_irq_chip;
+	int update;
+	int intcnt;
+	bool set_irq_mask;
+};
+
+static inline unsigned int to_reg(int gpio, enum ctrl_register reg_type)
+{
+	unsigned int reg;
+	int bank;
+
+	if (gpio < BANK0_NR_PINS)
+		bank = 0;
+	else if (gpio < BANK0_NR_PINS + BANK1_NR_PINS)
+		bank = 1;
+	else
+		bank = 2;
+
+	if (reg_type == CTRL_IN)
+		reg = GPIO_IN_CTRL_BASE + bank;
+	else
+		reg = GPIO_OUT_CTRL_BASE + bank;
+
+	return reg;
+}
+
+static void wcove_update_irq_mask(struct wcove_gpio *wg, int gpio)
+{
+	unsigned int reg, mask;
+
+	if (gpio < GROUP0_NR_IRQS) {
+		reg = IRQ_MASK_BASE;
+		mask = BIT(gpio % GROUP0_NR_IRQS);
+	} else {
+		reg = IRQ_MASK_BASE + 1;
+		mask = BIT((gpio - GROUP0_NR_IRQS) % GROUP1_NR_IRQS);
+	}
+
+	if (wg->set_irq_mask)
+		regmap_update_bits(wg->regmap, reg, mask, mask);
+	else
+		regmap_update_bits(wg->regmap, reg, mask, 0);
+}
+
+static void wcove_update_irq_ctrl(struct wcove_gpio *wg, int gpio)
+{
+	unsigned int reg = to_reg(gpio, CTRL_IN);
+
+	regmap_update_bits(wg->regmap, reg, CTLI_INTCNT_BE, wg->intcnt);
+}
+
+static int wcove_gpio_dir_in(struct gpio_chip *chip, unsigned int gpio)
+{
+	struct wcove_gpio *wg = gpiochip_get_data(chip);
+
+	return regmap_write(wg->regmap, to_reg(gpio, CTRL_OUT),
+			    CTLO_INPUT_SET);
+}
+
+static int wcove_gpio_dir_out(struct gpio_chip *chip, unsigned int gpio,
+				    int value)
+{
+	struct wcove_gpio *wg = gpiochip_get_data(chip);
+
+	return regmap_write(wg->regmap, to_reg(gpio, CTRL_OUT),
+			    CTLO_OUTPUT_SET | value);
+}
+
+static int wcove_gpio_get(struct gpio_chip *chip, unsigned int gpio)
+{
+	struct wcove_gpio *wg = gpiochip_get_data(chip);
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(wg->regmap, to_reg(gpio, CTRL_IN), &val);
+	if (ret)
+		return ret;
+
+	return val & 0x1;
+}
+
+static void wcove_gpio_set(struct gpio_chip *chip,
+				 unsigned int gpio, int value)
+{
+	struct wcove_gpio *wg = gpiochip_get_data(chip);
+
+	if (value)
+		regmap_update_bits(wg->regmap, to_reg(gpio, CTRL_OUT), 1, 1);
+	else
+		regmap_update_bits(wg->regmap, to_reg(gpio, CTRL_OUT), 1, 0);
+}
+
+static int wcove_gpio_set_single_ended(struct gpio_chip *chip,
+					unsigned int gpio,
+					enum single_ended_mode mode)
+{
+	struct wcove_gpio *wg = gpiochip_get_data(chip);
+
+	switch (mode) {
+	case LINE_MODE_OPEN_DRAIN:
+		return regmap_update_bits(wg->regmap, to_reg(gpio, CTRL_OUT),
+						CTLO_DRV_MASK, CTLO_DRV_OD);
+	case LINE_MODE_PUSH_PULL:
+		return regmap_update_bits(wg->regmap, to_reg(gpio, CTRL_OUT),
+						CTLO_DRV_MASK, CTLO_DRV_CMOS);
+	default:
+		break;
+	}
+
+	return -ENOTSUPP;
+}
+
+static int wcove_irq_type(struct irq_data *data, unsigned int type)
+{
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
+	struct wcove_gpio *wg = gpiochip_get_data(chip);
+
+	switch (type) {
+	case IRQ_TYPE_NONE:
+		wg->intcnt = CTLI_INTCNT_DIS;
+		break;
+	case IRQ_TYPE_EDGE_BOTH:
+		wg->intcnt = CTLI_INTCNT_BE;
+		break;
+	case IRQ_TYPE_EDGE_RISING:
+		wg->intcnt = CTLI_INTCNT_PE;
+		break;
+	case IRQ_TYPE_EDGE_FALLING:
+		wg->intcnt = CTLI_INTCNT_NE;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	wg->update |= UPDATE_IRQ_TYPE;
+
+	return 0;
+}
+
+static void wcove_bus_lock(struct irq_data *data)
+{
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
+	struct wcove_gpio *wg = gpiochip_get_data(chip);
+
+	mutex_lock(&wg->buslock);
+}
+
+static void wcove_bus_sync_unlock(struct irq_data *data)
+{
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
+	struct wcove_gpio *wg = gpiochip_get_data(chip);
+	int gpio = data->hwirq;
+
+	if (wg->update & UPDATE_IRQ_TYPE)
+		wcove_update_irq_ctrl(wg, gpio);
+	if (wg->update & UPDATE_IRQ_MASK)
+		wcove_update_irq_mask(wg, gpio);
+	wg->update = 0;
+
+	mutex_unlock(&wg->buslock);
+}
+
+static void wcove_irq_unmask(struct irq_data *data)
+{
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
+	struct wcove_gpio *wg = gpiochip_get_data(chip);
+
+	wg->set_irq_mask = false;
+	wg->update |= UPDATE_IRQ_MASK;
+}
+
+static void wcove_irq_mask(struct irq_data *data)
+{
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
+	struct wcove_gpio *wg = gpiochip_get_data(chip);
+
+	wg->set_irq_mask = true;
+	wg->update |= UPDATE_IRQ_MASK;
+}
+
+static struct irq_chip wcove_irqchip = {
+	.name			= "Whiskey Cove",
+	.irq_mask		= wcove_irq_mask,
+	.irq_unmask		= wcove_irq_unmask,
+	.irq_set_type		= wcove_irq_type,
+	.irq_bus_lock		= wcove_bus_lock,
+	.irq_bus_sync_unlock	= wcove_bus_sync_unlock,
+};
+
+static irqreturn_t wcove_gpio_irq_handler(int irq, void *data)
+{
+	struct wcove_gpio *wg = (struct wcove_gpio *)data;
+	unsigned int pending, virq, gpio, mask, offset;
+	u8 p[2];
+
+	if (regmap_bulk_read(wg->regmap, IRQ_STATUS_BASE, p, 2)) {
+		dev_err(wg->dev, "Failed to read irq status register\n");
+		return IRQ_NONE;
+	}
+
+	pending = p[0] | (p[1] << 8);
+	if (!pending)
+		return IRQ_NONE;
+
+	/* Iterate until no interrupt is pending */
+	while (pending) {
+		/* One iteration is for all pending bits */
+		for_each_set_bit(gpio, (const unsigned long *)&pending,
+						 GROUP0_NR_IRQS) {
+			offset = (gpio > GROUP0_NR_IRQS) ? 1 : 0;
+			mask = (offset == 1) ? BIT(gpio - GROUP0_NR_IRQS) :
+								BIT(gpio);
+			virq = irq_find_mapping(wg->chip.irqdomain, gpio);
+			handle_nested_irq(virq);
+			regmap_update_bits(wg->regmap, IRQ_STATUS_BASE + offset,
+								mask, mask);
+		}
+
+		/* Next iteration */
+		if (regmap_bulk_read(wg->regmap, IRQ_STATUS_BASE, p, 2)) {
+			dev_err(wg->dev, "Failed to read irq status\n");
+			break;
+		}
+
+		pending = p[0] | (p[1] << 8);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static void wcove_gpio_dbg_show(struct seq_file *s,
+				      struct gpio_chip *chip)
+{
+	unsigned int ctlo, ctli, irq_mask, irq_status;
+	struct wcove_gpio *wg = gpiochip_get_data(chip);
+	int gpio, offset, group, ret = 0;
+
+	for (gpio = 0; gpio < WCOVE_GPIO_NUM; gpio++) {
+		group = gpio < GROUP0_NR_IRQS ? 0 : 1;
+		ret += regmap_read(wg->regmap, to_reg(gpio, CTRL_OUT), &ctlo);
+		ret += regmap_read(wg->regmap, to_reg(gpio, CTRL_IN), &ctli);
+		ret += regmap_read(wg->regmap, IRQ_MASK_BASE + group,
+							&irq_mask);
+		ret += regmap_read(wg->regmap, IRQ_STATUS_BASE + group,
+							&irq_status);
+		if (ret) {
+			pr_err("Failed to read registers: ctrl out/in or irq status/mask\n");
+			break;
+		}
+
+		offset = gpio % 8;
+		seq_printf(s, " gpio-%-2d %s %s %s %s ctlo=%2x,%s %s\n",
+			   gpio, ctlo & CTLO_DIR_OUT ? "out" : "in ",
+			   ctli & 0x1 ? "hi" : "lo",
+			   ctli & CTLI_INTCNT_NE ? "fall" : "    ",
+			   ctli & CTLI_INTCNT_PE ? "rise" : "    ",
+			   ctlo,
+			   irq_mask & BIT(offset) ? "mask  " : "unmask",
+			   irq_status & BIT(offset) ? "pending" : "       ");
+	}
+}
+
+static int wcove_gpio_probe(struct platform_device *pdev)
+{
+	struct intel_soc_pmic *pmic;
+	struct wcove_gpio *wg;
+	int virq, ret, irq;
+	struct device *dev;
+
+	/*
+	 * This gpio platform device is created by a mfd device (see
+	 * drivers/mfd/intel_soc_pmic_bxtwc.c for details). Information
+	 * shared by all sub-devices created by the mfd device, the regmap
+	 * pointer for instance, is stored as driver data of the mfd device
+	 * driver.
+	 */
+	pmic = dev_get_drvdata(pdev->dev.parent);
+	if (!pmic)
+		return -ENODEV;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	dev = &pdev->dev;
+
+	wg = devm_kzalloc(dev, sizeof(*wg), GFP_KERNEL);
+	if (!wg)
+		return -ENOMEM;
+
+	wg->regmap_irq_chip = pmic->irq_chip_data_level2;
+
+	platform_set_drvdata(pdev, wg);
+
+	mutex_init(&wg->buslock);
+	wg->chip.label = KBUILD_MODNAME;
+	wg->chip.direction_input = wcove_gpio_dir_in;
+	wg->chip.direction_output = wcove_gpio_dir_out;
+	wg->chip.get = wcove_gpio_get;
+	wg->chip.set = wcove_gpio_set;
+	wg->chip.set_single_ended = wcove_gpio_set_single_ended,
+	wg->chip.base = -1;
+	wg->chip.ngpio = WCOVE_VGPIO_NUM;
+	wg->chip.can_sleep = true;
+	wg->chip.parent = pdev->dev.parent;
+	wg->chip.dbg_show = wcove_gpio_dbg_show;
+	wg->dev = dev;
+	wg->regmap = pmic->regmap;
+
+	ret = devm_gpiochip_add_data(dev, &wg->chip, wg);
+	if (ret) {
+		dev_err(dev, "Failed to add gpiochip: %d\n", ret);
+		return ret;
+	}
+
+	ret = gpiochip_irqchip_add(&wg->chip, &wcove_irqchip, 0,
+			     handle_simple_irq, IRQ_TYPE_NONE);
+	if (ret) {
+		dev_err(dev, "Failed to add irqchip: %d\n", ret);
+		return ret;
+	}
+
+	virq = regmap_irq_get_virq(wg->regmap_irq_chip, irq);
+	if (virq < 0) {
+		dev_err(dev, "Failed to get virq by irq %d\n", irq);
+		return virq;
+	}
+
+	ret = devm_request_threaded_irq(dev, virq, NULL,
+		wcove_gpio_irq_handler, IRQF_ONESHOT, pdev->name, wg);
+	if (ret) {
+		dev_err(dev, "Failed to request irq %d\n", virq);
+		return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * Whiskey Cove PMIC itself is a analog device(but with digital control
+ * interface) providing power management support for other devices in
+ * the accompanied SoC, so we have no .pm for Whiskey Cove GPIO driver.
+ */
+static struct platform_driver wcove_gpio_driver = {
+	.driver = {
+		.name = "bxt_wcove_gpio",
+	},
+	.probe = wcove_gpio_probe,
+};
+
+module_platform_driver(wcove_gpio_driver);
+
+MODULE_AUTHOR("Ajay Thomas <ajay.thomas.david.rajamanickam@intel.com>");
+MODULE_AUTHOR("Bin Gao <bin.gao@intel.com>");
+MODULE_DESCRIPTION("Intel Whiskey Cove GPIO Driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:bxt_wcove_gpio");