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Date:   Sun,  8 Jan 2017 22:32:05 +0000
From:   Sudip Mukherjee <sudipm.mukherjee@...il.com>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Alexandre Courbot <gnurou@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        gnomes@...rguk.ukuu.org.uk
Cc:     linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
        linux-gpio@...r.kernel.org,
        Sudip Mukherjee <sudip.mukherjee@...ethink.co.uk>
Subject: [PATCH v8 1/3] gpio: exar: add gpio for exar cards

From: Sudip Mukherjee <sudip.mukherjee@...ethink.co.uk>

Exar XR17V352/354/358 chips have 16 multi-purpose inputs/outputs which
can be controlled using gpio interface.

Add the gpio specific code.

Signed-off-by: Sudip Mukherjee <sudip.mukherjee@...ethink.co.uk>
---
 drivers/gpio/Kconfig     |   7 ++
 drivers/gpio/Makefile    |   1 +
 drivers/gpio/gpio-exar.c | 238 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 246 insertions(+)
 create mode 100644 drivers/gpio/gpio-exar.c

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index d5d3654..eaf8d29 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -185,6 +185,13 @@ config GPIO_ETRAXFS
 	help
 	  Say yes here to support the GPIO controller on Axis ETRAX FS SoCs.
 
+config GPIO_EXAR
+	tristate "Support for GPIO pins on XR17V352/354/358"
+	depends on SERIAL_8250_EXAR
+	help
+	  Selecting this option will enable handling of GPIO pins present
+	  on Exar XR17V352/354/358 chips.
+
 config GPIO_GE_FPGA
 	bool "GE FPGA based GPIO"
 	depends on GE_FPGA
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index a7676b8..09f6aebb 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -46,6 +46,7 @@ obj-$(CONFIG_GPIO_DWAPB)	+= gpio-dwapb.o
 obj-$(CONFIG_GPIO_EM)		+= gpio-em.o
 obj-$(CONFIG_GPIO_EP93XX)	+= gpio-ep93xx.o
 obj-$(CONFIG_GPIO_ETRAXFS)	+= gpio-etraxfs.o
+obj-$(CONFIG_GPIO_EXAR)		+= gpio-exar.o
 obj-$(CONFIG_GPIO_F7188X)	+= gpio-f7188x.o
 obj-$(CONFIG_GPIO_GE_FPGA)	+= gpio-ge.o
 obj-$(CONFIG_GPIO_GPIO_MM)	+= gpio-gpio-mm.o
diff --git a/drivers/gpio/gpio-exar.c b/drivers/gpio/gpio-exar.c
new file mode 100644
index 0000000..b7d1363
--- /dev/null
+++ b/drivers/gpio/gpio-exar.c
@@ -0,0 +1,238 @@
+/*
+ * GPIO driver for Exar XR17V35X chip
+ *
+ * Copyright (C) 2015 Sudip Mukherjee <sudip.mukherjee@...ethink.co.uk>
+ *
+ * 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/device.h>
+#include <linux/gpio.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/platform_device.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
+
+#define DRIVER_NAME "gpio_exar"
+
+static LIST_HEAD(exar_list);
+static DEFINE_MUTEX(exar_list_mtx);
+DEFINE_IDA(ida_index);
+
+struct exar_gpio_chip {
+	struct gpio_chip gpio_chip;
+	struct pci_dev *pcidev;
+	struct mutex lock;
+	struct list_head list;
+	int index;
+	void __iomem *regs;
+	char name[16];
+};
+
+#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)
+{
+	dev_dbg(chip->gpio_chip.parent, "regs=%p offset=%x\n",
+		chip->regs, offset);
+
+	return readb(chip->regs + offset);
+}
+
+static inline void write_exar_reg(struct exar_gpio_chip *chip, int offset,
+				  int value)
+{
+	dev_dbg(chip->gpio_chip.parent,
+		"regs=%p value=%x offset=%x\n", chip->regs, value,
+		offset);
+	writeb(value, chip->regs + offset);
+}
+
+static void exar_update(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_set_direction(struct gpio_chip *chip, int direction,
+			      unsigned int offset)
+{
+	if (offset < 8)
+		exar_update(chip, EXAR_OFFSET_MPIOSEL_LO, direction,
+			    offset);
+	else
+		exar_update(chip, EXAR_OFFSET_MPIOSEL_HI, direction,
+			    offset - 8);
+	return 0;
+}
+
+static int exar_direction_output(struct gpio_chip *chip, unsigned int offset,
+				 int value)
+{
+	return exar_set_direction(chip, 0, offset);
+}
+
+static int exar_direction_input(struct gpio_chip *chip, unsigned int offset)
+{
+	return exar_set_direction(chip, 1, offset);
+}
+
+static int exar_get(struct gpio_chip *chip, unsigned int reg)
+{
+	struct exar_gpio_chip *exar_gpio = to_exar_chip(chip);
+	int value;
+
+	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) >> offset;
+	else
+		val = exar_get(chip, EXAR_OFFSET_MPIOSEL_HI) >>
+			       (offset - 8);
+
+	return val & 0x01;
+}
+
+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) >> offset;
+	else
+		val = exar_get(chip, EXAR_OFFSET_MPIOLVL_HI) >>
+			       (offset - 8);
+	return val & 0x01;
+}
+
+static void exar_set_value(struct gpio_chip *chip, unsigned int offset,
+			   int value)
+{
+	if (offset < 8)
+		exar_update(chip, EXAR_OFFSET_MPIOLVL_LO, value,
+			    offset);
+	else
+		exar_update(chip, EXAR_OFFSET_MPIOLVL_HI, value,
+			    offset - 8);
+}
+
+static int gpio_exar_probe(struct platform_device *pdev)
+{
+	struct pci_dev *dev = platform_get_drvdata(pdev);
+	struct exar_gpio_chip *exar_gpio;
+	void __iomem *p;
+	int index = 1;
+	int ret;
+
+	if (dev->vendor != PCI_VENDOR_ID_EXAR)
+		return -ENODEV;
+
+	p = pci_ioremap_bar(dev, 0);
+	if (!p)
+		return -ENOMEM;
+
+	exar_gpio = devm_kzalloc(&dev->dev, sizeof(*exar_gpio), GFP_KERNEL);
+	if (!exar_gpio)
+		return -ENOMEM;
+
+	mutex_init(&exar_gpio->lock);
+	INIT_LIST_HEAD(&exar_gpio->list);
+
+	index = ida_simple_get(&ida_index, 0, 0, GFP_KERNEL);
+	mutex_lock(&exar_list_mtx);
+
+	sprintf(exar_gpio->name, "exar_gpio%d", index);
+	exar_gpio->gpio_chip.label = exar_gpio->name;
+	exar_gpio->gpio_chip.parent = &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->regs = p;
+	exar_gpio->index = index;
+	exar_gpio->pcidev = dev;
+
+	ret = gpiochip_add(&exar_gpio->gpio_chip);
+	if (ret)
+		goto err_destroy;
+
+	list_add_tail(&exar_gpio->list, &exar_list);
+	mutex_unlock(&exar_list_mtx);
+
+	return 0;
+
+err_destroy:
+	mutex_unlock(&exar_list_mtx);
+	mutex_destroy(&exar_gpio->lock);
+	return ret;
+}
+
+static int gpio_exar_remove(struct platform_device *pdev)
+{
+	struct exar_gpio_chip *exar_gpio, *exar_temp;
+	struct pci_dev *pcidev;
+	int index;
+
+	pcidev = platform_get_drvdata(pdev);
+
+	mutex_lock(&exar_list_mtx);
+	list_for_each_entry_safe(exar_gpio, exar_temp, &exar_list, list) {
+		if (exar_gpio->pcidev == pcidev) {
+			list_del(&exar_gpio->list);
+			break;
+		}
+	}
+	mutex_unlock(&exar_list_mtx);
+
+	index = exar_gpio->index;
+	gpiochip_remove(&exar_gpio->gpio_chip);
+	mutex_destroy(&exar_gpio->lock);
+	ida_simple_remove(&ida_index, index);
+
+	return 0;
+}
+
+static struct platform_driver gpio_exar_driver = {
+	.probe	= gpio_exar_probe,
+	.remove	= gpio_exar_remove,
+	.driver	= {
+		.name = DRIVER_NAME,
+	},
+};
+
+module_platform_driver(gpio_exar_driver);
+
+MODULE_ALIAS("platform:" DRIVER_NAME);
+MODULE_DESCRIPTION("Exar GPIO driver");
+MODULE_AUTHOR("Sudip Mukherjee <sudip.mukherjee@...ethink.co.uk>");
+MODULE_LICENSE("GPL");
-- 
2.7.4

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