Date:	Sat, 19 Dec 2015 13:40:04 +0530
From:	Sudip Mukherjee <sudipm.mukherjee@...il.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.com>
Cc:	linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
	Sudip Mukherjee <sudipm.mukherjee@...il.com>
Subject: [PATCH] serial: 8250: add gpio support to exar

Exar XR17V352/354/358 chips have 16 multi-purpose inputs/outputs which
can be controlled using gpio interface.
Add support to use these pins and select GPIO_SYSFS also so that these
pins can be used from the userspace through sysfs.

Tested-by: Rob Groner <rgroner@....com>
Signed-off-by: Sudip Mukherjee <sudip@...torindia.org>
---
 drivers/tty/serial/8250/8250.h      |  14 ++
 drivers/tty/serial/8250/8250_gpio.c | 276 ++++++++++++++++++++++++++++++++++++
 drivers/tty/serial/8250/8250_pci.c  |  26 +++-
 drivers/tty/serial/8250/Kconfig     |   8 ++
 drivers/tty/serial/8250/Makefile    |   1 +
 5 files changed, 324 insertions(+), 1 deletion(-)
 create mode 100644 drivers/tty/serial/8250/8250_gpio.c

diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index d54dcd8..507447d 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -217,6 +217,20 @@ static inline int serial_index(struct uart_port *port)
 	return port->minor - 64;
 }
 
+#ifdef CONFIG_GPIOLIB
+int xr17v35x_gpio_init(struct pci_dev *dev,
+		       struct uart_8250_port *port);
+void xr17v35x_gpio_exit(struct uart_8250_port *port);
+#else
+static inline int xr17v35x_gpio_init(struct pci_dev *dev,
+				     struct uart_8250_port *port)
+{
+	return 0;
+}
+
+static void xr17v35x_gpio_exit(struct uart_8250_port *port) { }
+#endif
+
 #if 0
 #define DEBUG_INTR(fmt...)	printk(fmt)
 #else
diff --git a/drivers/tty/serial/8250/8250_gpio.c b/drivers/tty/serial/8250/8250_gpio.c
new file mode 100644
index 0000000..1b14dd2
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_gpio.c
@@ -0,0 +1,276 @@
+/*
+ * GPIO driver for Exar XR17V35X chip
+ *
+ * Copyright (C) 2015 Sudip Mukherjee <sudipm.mukherjee@...il.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.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/pci.h>
+#include <linux/gpio.h>
+#include "8250.h"
+
+#define EXAR_OFFSET_MPIOLVL_LO 0x90
+#define EXAR_OFFSET_MPIOSEL_LO 0x93
+#define EXAR_OFFSET_MPIOLVL_HI 0x96
+#define EXAR_OFFSET_MPIOSEL_HI 0x99
+
+static LIST_HEAD(exar_list);
+static DEFINE_MUTEX(exar_mtx); /* lock while manipulating the list */
+
+struct exar_gpio_chip {
+	struct gpio_chip gpio_chip;
+	struct mutex lock;
+	struct uart_8250_port *port;
+	struct list_head list;
+	int index;
+	void __iomem *regs;
+};
+
+#define to_exar_chip(n) container_of(n, struct exar_gpio_chip, gpio_chip)
+
+static inline unsigned int read_exar_reg(struct exar_gpio_chip *chip,
+					 int offset)
+{
+	if (!chip) {
+		pr_err("%s exar_gpio is NULL\n", __func__);
+		return -ENOMEM;
+	}
+	pr_debug("%s regs=%p offset=%x\n", __func__, chip->regs, offset);
+
+	return readb(chip->regs + offset);
+}
+
+static inline void write_exar_reg(struct exar_gpio_chip *chip, int offset,
+				  int value)
+{
+	if (!chip) {
+		pr_err("%s exar_gpio is NULL\n", __func__);
+		return;
+	}
+	pr_debug("%s regs=%p value=%x offset=%x\n", __func__, chip->regs,
+		 value, offset);
+
+	writeb(value, chip->regs + offset);
+}
+
+void xr17v35x_gpio_exit(struct uart_8250_port *port)
+{
+	struct exar_gpio_chip *exar_gpio, *exar_temp1, *exar_temp2;
+
+	if (!port)
+		return;
+
+	exar_gpio = port->port.private_data;
+	if (!exar_gpio)
+		return;
+
+	mutex_lock(&exar_mtx);
+	list_for_each_entry_safe(exar_temp1, exar_temp2, &exar_list, list) {
+		if (exar_temp1->index == exar_gpio->index) {
+			list_del(&exar_temp1->list);
+			break;
+		}
+	}
+	mutex_unlock(&exar_mtx);
+
+	gpiochip_remove(&exar_gpio->gpio_chip);
+	mutex_destroy(&exar_gpio->lock);
+	iounmap(exar_gpio->regs);
+}
+EXPORT_SYMBOL(xr17v35x_gpio_exit);
+
+static void exar_set(struct gpio_chip *chip, unsigned int reg, int val,
+		     unsigned int offset)
+{
+	struct exar_gpio_chip *exar_gpio = to_exar_chip(chip);
+	int temp;
+
+	mutex_lock(&exar_gpio->lock);
+	temp = read_exar_reg(exar_gpio, reg);
+	temp &= ~(1 << offset);
+	temp |= val << offset;
+	write_exar_reg(exar_gpio, reg, temp);
+	mutex_unlock(&exar_gpio->lock);
+}
+
+static int exar_direction_output(struct gpio_chip *chip, unsigned int offset,
+				 int value)
+{
+	if (offset < 8)
+		exar_set(chip, EXAR_OFFSET_MPIOSEL_LO, 0, offset);
+	else
+		exar_set(chip, EXAR_OFFSET_MPIOSEL_HI, 0, offset - 8);
+	return 0;
+}
+
+static int exar_direction_input(struct gpio_chip *chip, unsigned int offset)
+{
+	if (offset < 8)
+		exar_set(chip, EXAR_OFFSET_MPIOSEL_LO, 1, offset);
+	else
+		exar_set(chip, EXAR_OFFSET_MPIOSEL_HI, 1, offset - 8);
+	return 0;
+}
+
+static int exar_get(struct gpio_chip *chip, unsigned int reg)
+{
+	int value;
+	struct exar_gpio_chip *exar_gpio = to_exar_chip(chip);
+
+	if (!exar_gpio) {
+		pr_err("%s exar_gpio is NULL\n", __func__);
+		return -ENOMEM;
+	}
+
+	mutex_lock(&exar_gpio->lock);
+	value = read_exar_reg(exar_gpio, reg);
+	mutex_unlock(&exar_gpio->lock);
+
+	return value;
+}
+
+static int exar_get_direction(struct gpio_chip *chip, unsigned int offset)
+{
+	int val;
+
+	if (offset < 8) {
+		val = exar_get(chip, EXAR_OFFSET_MPIOSEL_LO);
+	} else {
+		val = exar_get(chip, EXAR_OFFSET_MPIOSEL_HI);
+		offset -= 8;
+	}
+
+	if (val > 0) {
+		val >>= offset;
+		val &= 0x01;
+	}
+
+	return val;
+}
+
+static int exar_get_value(struct gpio_chip *chip, unsigned int offset)
+{
+	int val;
+
+	if (offset < 8) {
+		val = exar_get(chip, EXAR_OFFSET_MPIOLVL_LO);
+	} else {
+		val = exar_get(chip, EXAR_OFFSET_MPIOLVL_HI);
+		offset -= 8;
+	}
+	val >>= offset;
+	val &= 0x01;
+
+	return val;
+}
+
+static void exar_set_value(struct gpio_chip *chip, unsigned int offset,
+			   int value)
+{
+	if (offset < 8)
+		exar_set(chip, EXAR_OFFSET_MPIOLVL_LO, value, offset);
+	else
+		exar_set(chip, EXAR_OFFSET_MPIOLVL_HI, value, offset - 8);
+}
+
+int xr17v35x_gpio_init(struct pci_dev *dev, struct uart_8250_port *port)
+{
+	struct exar_gpio_chip *exar_gpio, *exar_temp;
+	int ret;
+	void __iomem *p;
+	char *buf;
+	int index = 1;
+
+	p = pci_ioremap_bar(dev, 0);
+	if (!p)
+		return -ENOMEM;
+
+	exar_gpio = devm_kzalloc(&dev->dev, sizeof(*exar_gpio), GFP_KERNEL);
+	if (!exar_gpio) {
+		ret = -ENOMEM;
+		goto err_unmap;
+	}
+
+	/* assuming we will never have more than 99 boards */
+	buf = devm_kzalloc(&dev->dev, strlen("exar_gpio") + 3, GFP_KERNEL);
+	if (!buf) {
+		ret = -ENOMEM;
+		goto err_unmap;
+	}
+
+	mutex_init(&exar_gpio->lock);
+	INIT_LIST_HEAD(&exar_gpio->list);
+
+	mutex_lock(&exar_mtx);
+	/* find the first unused index */
+	list_for_each_entry(exar_temp, &exar_list, list) {
+		if (exar_temp->index == index) {
+			index++;
+			continue;
+		}
+	}
+
+	if (index > 99) {
+		pr_err("We can support max. 99 boards\n");
+		ret = -ENODEV;
+		goto err_destroy;
+	}
+	sprintf(buf, "exar_gpio%d", index);
+	exar_gpio->gpio_chip.label = buf;
+	exar_gpio->gpio_chip.dev = &dev->dev;
+	exar_gpio->gpio_chip.direction_output = exar_direction_output;
+	exar_gpio->gpio_chip.direction_input = exar_direction_input;
+	exar_gpio->gpio_chip.get_direction = exar_get_direction;
+	exar_gpio->gpio_chip.get = exar_get_value;
+	exar_gpio->gpio_chip.set = exar_set_value;
+	exar_gpio->gpio_chip.base = -1;
+	exar_gpio->gpio_chip.ngpio = 16;
+	exar_gpio->gpio_chip.owner = THIS_MODULE;
+	exar_gpio->regs = p;
+	exar_gpio->index = index;
+
+	ret = gpiochip_add(&exar_gpio->gpio_chip);
+	if (ret)
+		goto err_destroy;
+
+	exar_gpio->port = port;
+	port->port.private_data = exar_gpio;
+
+	list_add_tail(&exar_gpio->list, &exar_list);
+	mutex_unlock(&exar_mtx);
+
+	return 0;
+
+err_destroy:
+	mutex_unlock(&exar_mtx);
+	mutex_destroy(&exar_gpio->lock);
+err_unmap:
+	iounmap(p);
+	return ret;
+}
+EXPORT_SYMBOL(xr17v35x_gpio_init);
+
+static void __exit exar_gpio_exit(void)
+{
+}
+
+module_exit(exar_gpio_exit);
+
+static int __init exar_gpio_init(void)
+{
+	return 0;
+}
+
+module_init(exar_gpio_init);
+
+MODULE_DESCRIPTION("Exar GPIO driver");
+MODULE_AUTHOR("Sudip Mukherjee <sudipm.mukherjee@...il.com>");
+MODULE_LICENSE("GPL");
diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
index 4097f3f..d3e3489 100644
--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/drivers/tty/serial/8250/8250_pci.c
@@ -1764,12 +1764,24 @@ xr17v35x_has_slave(struct serial_private *priv)
 	        (dev_id == PCI_DEVICE_ID_EXAR_XR17V8358));
 }
 
+static void pci_xr17v35x_exit(struct pci_dev *dev)
+{
+	struct serial_private *priv = pci_get_drvdata(dev);
+	struct uart_8250_port *port = NULL;
+
+	if (priv)
+		port = serial8250_get_port(priv->line[0]);
+
+	xr17v35x_gpio_exit(port);
+}
+
 static int
 pci_xr17v35x_setup(struct serial_private *priv,
 		  const struct pciserial_board *board,
 		  struct uart_8250_port *port, int idx)
 {
 	u8 __iomem *p;
+	int ret;
 
 	p = pci_ioremap_bar(priv->dev, 0);
 	if (p == NULL)
@@ -1807,7 +1819,14 @@ pci_xr17v35x_setup(struct serial_private *priv,
 	writeb(128, p + UART_EXAR_RXTRG);
 	iounmap(p);
 
-	return pci_default_setup(priv, board, port, idx);
+	ret = pci_default_setup(priv, board, port, idx);
+	if (ret)
+		return ret;
+
+	if (idx == 0 && priv->dev->vendor == PCI_VENDOR_ID_EXAR)
+		ret = xr17v35x_gpio_init(priv->dev, port);
+
+	return ret;
 }
 
 #define PCI_DEVICE_ID_COMMTECH_4222PCI335 0x0004
@@ -2407,6 +2426,7 @@ static struct pci_serial_quirk pci_serial_quirks[] __refdata = {
 		.subvendor	= PCI_ANY_ID,
 		.subdevice	= PCI_ANY_ID,
 		.setup		= pci_xr17v35x_setup,
+		.exit		= pci_xr17v35x_exit,
 	},
 	{
 		.vendor = PCI_VENDOR_ID_EXAR,
@@ -2414,6 +2434,7 @@ static struct pci_serial_quirk pci_serial_quirks[] __refdata = {
 		.subvendor	= PCI_ANY_ID,
 		.subdevice	= PCI_ANY_ID,
 		.setup		= pci_xr17v35x_setup,
+		.exit		= pci_xr17v35x_exit,
 	},
 	{
 		.vendor = PCI_VENDOR_ID_EXAR,
@@ -2421,6 +2442,7 @@ static struct pci_serial_quirk pci_serial_quirks[] __refdata = {
 		.subvendor	= PCI_ANY_ID,
 		.subdevice	= PCI_ANY_ID,
 		.setup		= pci_xr17v35x_setup,
+		.exit		= pci_xr17v35x_exit,
 	},
 	{
 		.vendor = PCI_VENDOR_ID_EXAR,
@@ -2428,6 +2450,7 @@ static struct pci_serial_quirk pci_serial_quirks[] __refdata = {
 		.subvendor	= PCI_ANY_ID,
 		.subdevice	= PCI_ANY_ID,
 		.setup		= pci_xr17v35x_setup,
+		.exit		= pci_xr17v35x_exit,
 	},
 	{
 		.vendor = PCI_VENDOR_ID_EXAR,
@@ -2435,6 +2458,7 @@ static struct pci_serial_quirk pci_serial_quirks[] __refdata = {
 		.subvendor	= PCI_ANY_ID,
 		.subdevice	= PCI_ANY_ID,
 		.setup		= pci_xr17v35x_setup,
+		.exit		= pci_xr17v35x_exit,
 	},
 	/*
 	 * Xircom cards
diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index b03cb517..852f1d2 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -386,3 +386,11 @@ config SERIAL_OF_PLATFORM
 	  are probed through devicetree, including Open Firmware based
 	  PowerPC systems and embedded systems on architectures using the
 	  flattened device tree format.
+
+config SERIAL_8250_EXAR_GPIO
+	tristate "Support for GPIO pins on XR17V352/354/358"
+	depends on SERIAL_8250_PCI && GPIOLIB
+	select GPIO_SYSFS
+	help
+	  Selecting this option will enable handling of GPIO pins present
+	  on Exar XR17V352/354/358 chips.
diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
index 4ecb80d..bcf5f14 100644
--- a/drivers/tty/serial/8250/Makefile
+++ b/drivers/tty/serial/8250/Makefile
@@ -29,5 +29,6 @@ obj-$(CONFIG_SERIAL_8250_UNIPHIER)	+= 8250_uniphier.o
 obj-$(CONFIG_SERIAL_8250_INGENIC)	+= 8250_ingenic.o
 obj-$(CONFIG_SERIAL_8250_MID)		+= 8250_mid.o
 obj-$(CONFIG_SERIAL_8250_OF)		+= 8250_of.o
+obj-$(CONFIG_SERIAL_8250_EXAR_GPIO)	+= 8250_gpio.o
 
 CFLAGS_8250_ingenic.o += -I$(srctree)/scripts/dtc/libfdt
-- 
1.9.1

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