Date:	Wed, 11 May 2016 09:00:42 +0200
From:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
To:	linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	kernel@...gutronix.de
Subject: [PATCH RFC v3 3/4] gpio: new driver to work with a 8x12 siox

This patch is only to demonstrate how patch 1 of this series is intended
to be used. So don't apply and I intentionally didn't add a sign-off.
This still needs some work (dt-binding, some questions in code marked
with XXX).

Anyhow, if you want to give feedback, don't hesitate ...

---
 drivers/gpio/Kconfig     |   5 +
 drivers/gpio/Makefile    |   1 +
 drivers/gpio/gpio-siox.c | 290 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 296 insertions(+)
 create mode 100644 drivers/gpio/gpio-siox.c

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 5f3429f0bf46..6383473fd2f7 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -363,6 +363,11 @@ config GPIO_RCAR
 	help
 	  Say yes here to support GPIO on Renesas R-Car SoCs.
 
+config GPIO_SIOX
+	tristate "SIOX GPIO support"
+	depends on SIOX
+	select GPIOLIB_IRQCHIP
+
 config GPIO_SPEAR_SPICS
 	bool "ST SPEAr13xx SPI Chip Select as GPIO support"
 	depends on PLAT_SPEAR
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 1e0b74f3b1ed..4616f3d743d7 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -98,6 +98,7 @@ obj-$(CONFIG_GPIO_TC3589X)	+= gpio-tc3589x.o
 obj-$(CONFIG_ARCH_TEGRA)	+= gpio-tegra.o
 obj-$(CONFIG_GPIO_TIMBERDALE)	+= gpio-timberdale.o
 obj-$(CONFIG_GPIO_PALMAS)	+= gpio-palmas.o
+obj-$(CONFIG_GPIO_SIOX)		+= gpio-siox.o
 obj-$(CONFIG_GPIO_TPIC2810)	+= gpio-tpic2810.o
 obj-$(CONFIG_GPIO_TPS65086)	+= gpio-tps65086.o
 obj-$(CONFIG_GPIO_TPS65218)	+= gpio-tps65218.o
diff --git a/drivers/gpio/gpio-siox.c b/drivers/gpio/gpio-siox.c
new file mode 100644
index 000000000000..c03022f0c2ad
--- /dev/null
+++ b/drivers/gpio/gpio-siox.c
@@ -0,0 +1,290 @@
+/*
+ * Copyright (C) 2015 Pengutronix, Uwe Kleine-König <kernel@...gutronix.de>
+ *
+ * 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/module.h>
+#include <linux/siox.h>
+#include <linux/gpio/driver.h>
+#include <linux/of.h>
+
+struct gpio_siox_ddata {
+	struct gpio_chip gchip;
+	struct irq_chip ichip;
+	struct mutex lock;
+	u8 setdata[1];
+	u8 getdata[3];
+
+	spinlock_t irqlock;
+	u32 irq_enable;
+	u32 irq_status;
+	u32 irq_type[20];
+};
+
+/* XXX
+ * should set block until data is shifted out?
+ * should get block until new data is shifted in?
+ */
+static int gpio_siox_set_data(struct siox_device *sdevice, u8 status, u8 buf[])
+{
+	struct gpio_siox_ddata *ddata = dev_get_drvdata(&sdevice->dev);
+
+	mutex_lock(&ddata->lock);
+	buf[0] = ddata->setdata[0];
+	mutex_unlock(&ddata->lock);
+
+	return 0;
+}
+
+static int gpio_siox_get_data(struct siox_device *sdevice, const u8 buf[])
+{
+	struct gpio_siox_ddata *ddata = dev_get_drvdata(&sdevice->dev);
+	size_t offset;
+	u32 trigger;
+
+	mutex_lock(&ddata->lock);
+
+	spin_lock_irq(&ddata->irqlock);
+
+	for (offset = 0; offset < 12; ++offset) {
+		unsigned bitpos = 11 - offset;
+		unsigned gpiolevel = buf[bitpos / 8] & (1 << bitpos % 8);
+		unsigned prev_gpiolevel = ddata->getdata[bitpos / 8] & (1 << (bitpos % 8));
+
+		if (gpiolevel) {
+			if ((ddata->irq_type[offset] & IRQ_TYPE_LEVEL_HIGH) ||
+			    ((ddata->irq_type[offset] & IRQ_TYPE_EDGE_RISING) && !prev_gpiolevel))
+				ddata->irq_status |= 1 << offset;
+		} else {
+			if ((ddata->irq_type[offset] & IRQ_TYPE_LEVEL_LOW) ||
+			    ((ddata->irq_type[offset] & IRQ_TYPE_EDGE_FALLING) && prev_gpiolevel))
+				ddata->irq_status |= 1 << offset;
+		}
+	}
+
+	trigger = ddata->irq_status & ddata->irq_enable;
+
+	spin_unlock_irq(&ddata->irqlock);
+
+	for (offset = 0; offset < 12; ++offset) {
+		if (trigger & (1 << offset)) {
+			struct irq_domain *irqdomain = ddata->gchip.irqdomain;
+			unsigned int irq = irq_find_mapping(irqdomain, offset);
+
+			/*
+			 * Conceptually handle_nested_irq should call the flow
+			 * handler of the irq chip. But it doesn't, so we have
+			 * to clean the irq_status here.
+			 */
+			spin_lock_irq(&ddata->irqlock);
+			ddata->irq_status &= ~(1 << offset);
+			spin_unlock_irq(&ddata->irqlock);
+
+			handle_nested_irq(irq);
+		}
+	}
+
+	ddata->getdata[0] = buf[0];
+	ddata->getdata[1] = buf[1];
+	ddata->getdata[2] = buf[2];
+
+	mutex_unlock(&ddata->lock);
+
+	return 0;
+}
+
+static void gpio_siox_irq_ack(struct irq_data *d)
+{
+	struct irq_chip *ic = irq_data_get_irq_chip(d);
+	struct gpio_siox_ddata *ddata =
+		container_of(ic, struct gpio_siox_ddata, ichip);
+
+	spin_lock_irq(&ddata->irqlock);
+	ddata->irq_status &= ~(1 << d->hwirq);
+	spin_unlock_irq(&ddata->irqlock);
+}
+
+static void gpio_siox_irq_mask(struct irq_data *d)
+{
+	struct irq_chip *ic = irq_data_get_irq_chip(d);
+	struct gpio_siox_ddata *ddata =
+		container_of(ic, struct gpio_siox_ddata, ichip);
+
+	spin_lock_irq(&ddata->irqlock);
+	ddata->irq_enable &= ~(1 << d->hwirq);
+	spin_unlock_irq(&ddata->irqlock);
+}
+
+static void gpio_siox_irq_unmask(struct irq_data *d)
+{
+	struct irq_chip *ic = irq_data_get_irq_chip(d);
+	struct gpio_siox_ddata *ddata =
+		container_of(ic, struct gpio_siox_ddata, ichip);
+
+	spin_lock_irq(&ddata->irqlock);
+	ddata->irq_enable |= 1 << d->hwirq;
+	spin_unlock_irq(&ddata->irqlock);
+}
+
+static int gpio_siox_irq_set_type(struct irq_data *d, u32 type)
+{
+	struct irq_chip *ic = irq_data_get_irq_chip(d);
+	struct gpio_siox_ddata *ddata =
+		container_of(ic, struct gpio_siox_ddata, ichip);
+
+	spin_lock_irq(&ddata->irqlock);
+	ddata->irq_type[d->hwirq] = type;
+	spin_unlock_irq(&ddata->irqlock);
+
+	return 0;
+}
+
+static int gpio_siox_get(struct gpio_chip *chip, unsigned offset)
+{
+	struct gpio_siox_ddata *ddata =
+		container_of(chip, struct gpio_siox_ddata, gchip);
+	int ret;
+
+	mutex_lock(&ddata->lock);
+
+	if (offset >= 12) {
+		unsigned bitpos = 19 - offset;
+		ret = ddata->setdata[0] & (1 << bitpos);
+	} else {
+		unsigned bitpos = 11 - offset;
+		ret = ddata->getdata[bitpos / 8] & (1 << (bitpos % 8));
+	}
+
+	mutex_unlock(&ddata->lock);
+
+	return ret;
+}
+
+static void gpio_siox_set(struct gpio_chip *chip, unsigned offset, int value)
+{
+	struct gpio_siox_ddata *ddata =
+		container_of(chip, struct gpio_siox_ddata, gchip);
+	u8 mask = 1 << (19 - offset);
+
+	mutex_lock(&ddata->lock);
+
+	if (value)
+		ddata->setdata[0] |= mask;
+	else
+		ddata->setdata[0] &= ~mask;
+
+	mutex_unlock(&ddata->lock);
+}
+
+static int gpio_siox_direction_input(struct gpio_chip *chip, unsigned offset)
+{
+	if (offset >= 12)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int gpio_siox_direction_output(struct gpio_chip *chip,
+				      unsigned offset, int value)
+{
+	if (offset < 12)
+		return -EINVAL;
+
+	gpio_siox_set(chip, offset, value);
+	return 0;
+}
+
+static int gpio_siox_get_direction(struct gpio_chip *chip, unsigned offset)
+{
+	if (offset < 12)
+		return 1; /* input */
+	else
+		return 0; /* output */
+}
+
+static int gpio_siox_probe(struct siox_device *sdevice)
+{
+	struct gpio_siox_ddata *ddata;
+	int ret;
+
+	ddata = devm_kzalloc(&sdevice->dev, sizeof(*ddata), GFP_KERNEL);
+	if (!ddata) {
+		dev_info(&sdevice->dev, "failed to allocate driver data\n");
+		return -ENOMEM;
+	}
+
+	dev_set_drvdata(&sdevice->dev, ddata);
+
+	mutex_init(&ddata->lock);
+	spin_lock_init(&ddata->irqlock);
+
+	ddata->gchip.base = -1;
+	ddata->gchip.can_sleep = 1;
+	ddata->gchip.dev = &sdevice->dev;
+	ddata->gchip.owner = THIS_MODULE;
+	ddata->gchip.get = gpio_siox_get;
+	ddata->gchip.set = gpio_siox_set;
+	ddata->gchip.direction_input = gpio_siox_direction_input;
+	ddata->gchip.direction_output = gpio_siox_direction_output;
+	ddata->gchip.get_direction = gpio_siox_get_direction;
+	ddata->gchip.ngpio = 20;
+
+	ddata->ichip.name = "siox-gpio";
+	ddata->ichip.irq_ack = gpio_siox_irq_ack;
+	ddata->ichip.irq_mask = gpio_siox_irq_mask;
+	ddata->ichip.irq_unmask = gpio_siox_irq_unmask;
+	ddata->ichip.irq_set_type = gpio_siox_irq_set_type;
+
+	ret = gpiochip_add(&ddata->gchip);
+	if (ret) {
+		dev_err(&sdevice->dev, "Failed to register gpio chip (%d)\n", ret);
+		goto err_gpiochip;
+	}
+
+	ret = gpiochip_irqchip_add(&ddata->gchip, &ddata->ichip,
+				   0, handle_level_irq, IRQ_TYPE_EDGE_RISING);
+	if (ret) {
+		dev_err(&sdevice->dev, "Failed to register irq chip (%d)\n", ret);
+err_gpiochip:
+		gpiochip_remove(&ddata->gchip);
+	}
+
+	return ret;
+}
+
+static int gpio_siox_remove(struct siox_device *sdevice)
+{
+	struct gpio_siox_ddata *ddata = dev_get_drvdata(&sdevice->dev);
+
+	gpiochip_remove(&ddata->gchip);
+	return 0;
+}
+
+static struct siox_driver gpio_siox_driver = {
+	.probe = gpio_siox_probe,
+	.remove = gpio_siox_remove,
+	.set_data = gpio_siox_set_data,
+	.get_data = gpio_siox_get_data,
+	.driver = {
+		.name = "gpio-siox",
+	},
+};
+
+static int __init gpio_siox_init(void)
+{
+	return siox_driver_register(&gpio_siox_driver);
+}
+module_init(gpio_siox_init);
+
+static void __exit gpio_siox_exit(void)
+{
+	siox_driver_unregister(&gpio_siox_driver);
+}
+module_exit(gpio_siox_exit);
+
+MODULE_AUTHOR("Uwe Kleine-Koenig <u.kleine-koenig@...gutronix.de>");
+MODULE_DESCRIPTION("SIOX gpio driver");
+MODULE_LICENSE("GPL v2");
-- 
2.8.0.rc3

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