gpio: add MSIC gpio driver

Add gpio support for Intel MSIC chips found in Intel Medfield platforms.
MSIC supports totally 24 GPIOs with 16 low voltage and 8 high voltage pins.
Driver uses MSIC mfd interface for MSIC access.

(Updated comment to indicate why locking is actually safe)
Signed-off-by: NMathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>

drivers/gpio/Kconfig

@@ -520,4 +520,12 @@ config GPIO_TPS65910
 	help
 	  Select this option to enable GPIO driver for the TPS65910
 	  chip family.
+
+config GPIO_MSIC
+	bool "Intel MSIC mixed signal gpio support"
+	depends on MFD_INTEL_MSIC
+	help
+	  Enable support for GPIO on intel MSIC controllers found in
+	  intel MID devices
+
 endif

drivers/gpio/Makefile

@@ -33,6 +33,7 @@ obj-$(CONFIG_GPIO_MCP23S08)	+= gpio-mcp23s08.o
 obj-$(CONFIG_GPIO_ML_IOH)	+= gpio-ml-ioh.o
 obj-$(CONFIG_GPIO_MPC5200)	+= gpio-mpc5200.o
 obj-$(CONFIG_GPIO_MPC8XXX)	+= gpio-mpc8xxx.o
+obj-$(CONFIG_GPIO_MSIC)		+= gpio-msic.o
 obj-$(CONFIG_GPIO_MSM_V1)	+= gpio-msm-v1.o
 obj-$(CONFIG_GPIO_MSM_V2)	+= gpio-msm-v2.o
 obj-$(CONFIG_GPIO_MXC)		+= gpio-mxc.o

drivers/gpio/gpio-msic.c

+/*
+ * Intel Medfield MSIC GPIO driver>
+ * Copyright (c) 2011, Intel Corporation.
+ *
+ * Author: Mathias Nyman <mathias.nyman@linux.intel.com>
+ * Based on intel_pmic_gpio.c
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/gpio.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/intel_msic.h>
+
+/* the offset for the mapping of global gpio pin to irq */
+#define MSIC_GPIO_IRQ_OFFSET	0x100
+
+#define MSIC_GPIO_DIR_IN	0
+#define MSIC_GPIO_DIR_OUT	BIT(5)
+#define MSIC_GPIO_TRIG_FALL	BIT(1)
+#define MSIC_GPIO_TRIG_RISE	BIT(2)
+
+/* masks for msic gpio output GPIOxxxxCTLO registers */
+#define MSIC_GPIO_DIR_MASK	BIT(5)
+#define MSIC_GPIO_DRV_MASK	BIT(4)
+#define MSIC_GPIO_REN_MASK	BIT(3)
+#define MSIC_GPIO_RVAL_MASK	(BIT(2) | BIT(1))
+#define MSIC_GPIO_DOUT_MASK	BIT(0)
+
+/* masks for msic gpio input GPIOxxxxCTLI registers */
+#define MSIC_GPIO_GLBYP_MASK	BIT(5)
+#define MSIC_GPIO_DBNC_MASK	(BIT(4) | BIT(3))
+#define MSIC_GPIO_INTCNT_MASK	(BIT(2) | BIT(1))
+#define MSIC_GPIO_DIN_MASK	BIT(0)
+
+#define MSIC_NUM_GPIO		24
+
+struct msic_gpio {
+	struct platform_device	*pdev;
+	struct mutex		buslock;
+	struct gpio_chip	chip;
+	int			irq;
+	unsigned		irq_base;
+	unsigned long		trig_change_mask;
+	unsigned		trig_type;
+};
+
+/*
+ * MSIC has 24 gpios, 16 low voltage (1.2-1.8v) and 8 high voltage (3v).
+ * Both the high and low voltage gpios are divided in two banks.
+ * GPIOs are numbered with GPIO0LV0 as gpio_base in the following order:
+ * GPIO0LV0..GPIO0LV7: low voltage, bank 0, gpio_base
+ * GPIO1LV0..GPIO1LV7: low voltage, bank 1,  gpio_base + 8
+ * GPIO0HV0..GPIO0HV3: high voltage, bank 0, gpio_base + 16
+ * GPIO1HV0..GPIO1HV3: high voltage, bank 1, gpio_base + 20
+ */
+
+static int msic_gpio_to_ireg(unsigned offset)
+{
+	if (offset >= MSIC_NUM_GPIO)
+		return -EINVAL;
+
+	if (offset < 8)
+		return INTEL_MSIC_GPIO0LV0CTLI - offset;
+	if (offset < 16)
+		return INTEL_MSIC_GPIO1LV0CTLI - offset + 8;
+	if (offset < 20)
+		return INTEL_MSIC_GPIO0HV0CTLI - offset + 16;
+
+	return INTEL_MSIC_GPIO1HV0CTLI - offset + 20;
+}
+
+static int msic_gpio_to_oreg(unsigned offset)
+{
+	if (offset >= MSIC_NUM_GPIO)
+		return -EINVAL;
+
+	if (offset < 8)
+		return INTEL_MSIC_GPIO0LV0CTLO - offset;
+	if (offset < 16)
+		return INTEL_MSIC_GPIO1LV0CTLO - offset + 8;
+	if (offset < 20)
+		return INTEL_MSIC_GPIO0HV0CTLO - offset + 16;
+
+	return INTEL_MSIC_GPIO1HV0CTLO + offset + 20;
+}
+
+static int msic_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
+{
+	int reg;
+
+	reg = msic_gpio_to_oreg(offset);
+	if (reg < 0)
+		return reg;
+
+	return intel_msic_reg_update(reg, MSIC_GPIO_DIR_IN, MSIC_GPIO_DIR_MASK);
+}
+
+static int msic_gpio_direction_output(struct gpio_chip *chip,
+			unsigned offset, int value)
+{
+	int reg;
+	unsigned mask;
+
+	value = (!!value) | MSIC_GPIO_DIR_OUT;
+	mask = MSIC_GPIO_DIR_MASK | MSIC_GPIO_DOUT_MASK;
+
+	reg = msic_gpio_to_oreg(offset);
+	if (reg < 0)
+		return reg;
+
+	return intel_msic_reg_update(reg, value, mask);
+}
+
+static int msic_gpio_get(struct gpio_chip *chip, unsigned offset)
+{
+	u8 r;
+	int ret;
+	int reg;
+
+	reg = msic_gpio_to_ireg(offset);
+	if (reg < 0)
+		return reg;
+
+	ret = intel_msic_reg_read(reg, &r);
+	if (ret < 0)
+		return ret;
+
+	return r & MSIC_GPIO_DIN_MASK;
+}
+
+static void msic_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
+{
+	int reg;
+
+	reg = msic_gpio_to_oreg(offset);
+	if (reg < 0)
+		return;
+
+	intel_msic_reg_update(reg, !!value , MSIC_GPIO_DOUT_MASK);
+}
+
+/*
+ * This is called from genirq with mg->buslock locked and
+ * irq_desc->lock held. We can not access the scu bus here, so we
+ * store the change and update in the bus_sync_unlock() function below
+ */
+static int msic_irq_type(struct irq_data *data, unsigned type)
+{
+	struct msic_gpio *mg = irq_data_get_irq_chip_data(data);
+	u32 gpio = data->irq - mg->irq_base;
+
+	if (gpio >= mg->chip.ngpio)
+		return -EINVAL;
+
+	/* mark for which gpio the trigger changed, protected by buslock */
+	mg->trig_change_mask |= (1 << gpio);
+	mg->trig_type = type;
+
+	return 0;
+}
+
+static int msic_gpio_to_irq(struct gpio_chip *chip, unsigned offset)
+{
+	struct msic_gpio *mg = container_of(chip, struct msic_gpio, chip);
+	return mg->irq_base + offset;
+}
+
+static void msic_bus_lock(struct irq_data *data)
+{
+	struct msic_gpio *mg = irq_data_get_irq_chip_data(data);
+	mutex_lock(&mg->buslock);
+}
+
+static void msic_bus_sync_unlock(struct irq_data *data)
+{
+	struct msic_gpio *mg = irq_data_get_irq_chip_data(data);
+	int offset;
+	int reg;
+	u8 trig = 0;
+
+	/* We can only get one change at a time as the buslock covers the
+	   entire transaction. The irq_desc->lock is dropped before we are
+	   called but that is fine */
+	if (mg->trig_change_mask) {
+		offset = __ffs(mg->trig_change_mask);
+
+		reg = msic_gpio_to_ireg(offset);
+		if (reg < 0)
+			goto out;
+
+		if (mg->trig_type & IRQ_TYPE_EDGE_RISING)
+			trig |= MSIC_GPIO_TRIG_RISE;
+		if (mg->trig_type & IRQ_TYPE_EDGE_FALLING)
+			trig |= MSIC_GPIO_TRIG_FALL;
+
+		intel_msic_reg_update(reg, trig, MSIC_GPIO_INTCNT_MASK);
+		mg->trig_change_mask = 0;
+	}
+out:
+	mutex_unlock(&mg->buslock);
+}
+
+/* Firmware does all the masking and unmasking for us, no masking here. */
+static void msic_irq_unmask(struct irq_data *data) { }
+
+static void msic_irq_mask(struct irq_data *data) { }
+
+static struct irq_chip msic_irqchip = {
+	.name			= "MSIC-GPIO",
+	.irq_mask		= msic_irq_mask,
+	.irq_unmask		= msic_irq_unmask,
+	.irq_set_type		= msic_irq_type,
+	.irq_bus_lock		= msic_bus_lock,
+	.irq_bus_sync_unlock	= msic_bus_sync_unlock,
+};
+
+static void msic_gpio_irq_handler(unsigned irq, struct irq_desc *desc)
+{
+	struct irq_data *data = irq_desc_get_irq_data(desc);
+	struct msic_gpio *mg = irq_data_get_irq_handler_data(data);
+	struct irq_chip *chip = irq_data_get_irq_chip(data);
+	struct intel_msic *msic = pdev_to_intel_msic(mg->pdev);
+	int i;
+	int bitnr;
+	u8 pin;
+	unsigned long pending = 0;
+
+	for (i = 0; i < (mg->chip.ngpio / BITS_PER_BYTE); i++) {
+		intel_msic_irq_read(msic, INTEL_MSIC_GPIO0LVIRQ + i, &pin);
+		pending = pin;
+
+		if (pending) {
+			for_each_set_bit(bitnr, &pending, BITS_PER_BYTE)
+				generic_handle_irq(mg->irq_base +
+						   (i * BITS_PER_BYTE) + bitnr);
+		}
+	}
+	chip->irq_eoi(data);
+}
+
+static int __devinit platform_msic_gpio_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct intel_msic_gpio_pdata *pdata = dev->platform_data;
+	struct msic_gpio *mg;
+	int irq = platform_get_irq(pdev, 0);
+	int retval;
+	int i;
+
+	if (irq < 0) {
+		dev_err(dev, "no IRQ line\n");
+		return -EINVAL;
+	}
+
+	if (!pdata || !pdata->gpio_base) {
+		dev_err(dev, "incorrect or missing platform data\n");
+		return -EINVAL;
+	}
+
+	mg = kzalloc(sizeof(*mg), GFP_KERNEL);
+	if (!mg)
+		return -ENOMEM;
+
+	dev_set_drvdata(dev, mg);
+
+	mg->pdev = pdev;
+	mg->irq = irq;
+	mg->irq_base = pdata->gpio_base + MSIC_GPIO_IRQ_OFFSET;
+	mg->chip.label = "msic_gpio";
+	mg->chip.direction_input = msic_gpio_direction_input;
+	mg->chip.direction_output = msic_gpio_direction_output;
+	mg->chip.get = msic_gpio_get;
+	mg->chip.set = msic_gpio_set;
+	mg->chip.to_irq = msic_gpio_to_irq;
+	mg->chip.base = pdata->gpio_base;
+	mg->chip.ngpio = MSIC_NUM_GPIO;
+	mg->chip.can_sleep = 1;
+	mg->chip.dev = dev;
+
+	mutex_init(&mg->buslock);
+
+	retval = gpiochip_add(&mg->chip);
+	if (retval) {
+		dev_err(dev, "Adding MSIC gpio chip failed\n");
+		goto err;
+	}
+
+	for (i = 0; i < mg->chip.ngpio; i++) {
+		irq_set_chip_data(i + mg->irq_base, mg);
+		irq_set_chip_and_handler_name(i + mg->irq_base,
+					      &msic_irqchip,
+					      handle_simple_irq,
+					      "demux");
+	}
+	irq_set_chained_handler(mg->irq, msic_gpio_irq_handler);
+	irq_set_handler_data(mg->irq, mg);
+
+	return 0;
+err:
+	kfree(mg);
+	return retval;
+}
+
+static struct platform_driver platform_msic_gpio_driver = {
+	.driver = {
+		.name		= "msic_gpio",
+		.owner		= THIS_MODULE,
+	},
+	.probe		= platform_msic_gpio_probe,
+};
+
+static int __init platform_msic_gpio_init(void)
+{
+	return platform_driver_register(&platform_msic_gpio_driver);
+}
+
+subsys_initcall(platform_msic_gpio_init);
+
+MODULE_AUTHOR("Mathias Nyman <mathias.nyman@linux.intel.com>");
+MODULE_DESCRIPTION("Intel Medfield MSIC GPIO driver");
+MODULE_LICENSE("GPL v2");