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build/patch/kernel/archive/odroidxu4-5.13/0041-ODROID-XU4-char-exynos-add-dev-gpiomem-device-for-ro.patch

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From 20db6052315208afee409c2f02ed672dbef7d39f Mon Sep 17 00:00:00 2001
From: Brian Kim <brian.kim@hardkernel.com>
Date: Tue, 10 Jan 2017 11:31:52 +0900
Subject: [PATCH 041/109] ODROID-XU4: char: exynos: add /dev/gpiomem device for
rootless user GPIO access
Signed-off-by: memeka <mihailescu2m@gmail.com>
Signed-off-by: Yang Deokgyu <secugyu@gmail.com>
Change-Id: Ia6b9596501223037ee3be3587d720f74a2494380
---
.../boot/dts/exynos5422-odroidxu3-common.dtsi | 7 +
drivers/char/Kconfig | 9 +
drivers/char/Makefile | 1 +
drivers/char/exynos-gpiomem.c | 270 ++++++++++++++++++
4 files changed, 287 insertions(+)
create mode 100644 drivers/char/exynos-gpiomem.c
diff --git a/arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi b/arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi
index e35af40a55cb..f218eb44da34 100644
--- a/arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi
+++ b/arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi
@@ -34,6 +34,13 @@ power-key {
};
};
+ gpiomem {
+ compatible = "samsung,exynos-gpiomem";
+ reg = <0x13400000 0x1000>,
+ <0x14010000 0x1000>;
+ status = "okay";
+ };
+
emmc_pwrseq: pwrseq {
pinctrl-0 = <&emmc_nrst_pin>;
pinctrl-names = "default";
diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index d229a2d0c017..530d3af84aa8 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -471,6 +471,15 @@ config ADI
and SSM (Silicon Secured Memory). Intended consumers of this
driver include crash and makedumpfile.
+config EXYNOS_GPIOMEM
+ tristate "/dev/gpiomem rootless GPIO access via mmap() on the EXYNOS"
+ default m
+ help
+ Provides users with root-free access to the GPIO registers
+ on EXYNOS. Calling mmap(/dev/gpiomem) will map the GPIO register
+ page to the user's pointer. This drvier can allow to access gpio
+ memory area in user account.
+
endmenu
config RANDOM_TRUST_CPU
diff --git a/drivers/char/Makefile b/drivers/char/Makefile
index ffce287ef415..923df22cf799 100644
--- a/drivers/char/Makefile
+++ b/drivers/char/Makefile
@@ -47,3 +47,4 @@ obj-$(CONFIG_PS3_FLASH) += ps3flash.o
obj-$(CONFIG_XILLYBUS) += xillybus/
obj-$(CONFIG_POWERNV_OP_PANEL) += powernv-op-panel.o
obj-$(CONFIG_ADI) += adi.o
+obj-$(CONFIG_EXYNOS_GPIOMEM) += exynos-gpiomem.o
diff --git a/drivers/char/exynos-gpiomem.c b/drivers/char/exynos-gpiomem.c
new file mode 100644
index 000000000000..5dd684d48ffc
--- /dev/null
+++ b/drivers/char/exynos-gpiomem.c
@@ -0,0 +1,270 @@
+/*
+ * linux/drivers/char/exynos-gpiomem.c
+ *
+ * GPIO memory device driver
+ *
+ * Creates a chardev /dev/gpiomem which will provide user access to
+ * the EXYNOS's GPIO registers when it is mmap()'d.
+ * No longer need root for user GPIO access, but without relaxing permissions
+ * on /dev/mem.
+ *
+ * Copyright (c) 2017 Hardkernel Co., Ltd.
+ *
+ * This driver is based on bcm2835-gpiomem.c in Raspberrypi's linux kernel 4.4:
+ * Written by Luke Wren <luke@raspberrypi.org>
+ * Copyright (c) 2015, Raspberry Pi (Trading) Ltd.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions, and the following disclaimer,
+ * without modification.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. The names of the above-listed copyright holders may not be used
+ * to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * ALTERNATIVELY, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2, as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/cdev.h>
+#include <linux/pagemap.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <asm/io.h>
+
+#define DEVICE_NAME "exynos-gpiomem"
+#define DRIVER_NAME "gpiomem-exynos"
+#define DEVICE_MINOR 0
+
+struct exynos_gpiomem_instance {
+ unsigned long gpio_regs_phys[32];
+ int gpio_area_count;
+ struct device *dev;
+};
+
+static struct cdev exynos_gpiomem_cdev;
+static dev_t exynos_gpiomem_devid;
+static struct class *exynos_gpiomem_class;
+static struct device *exynos_gpiomem_dev;
+static struct exynos_gpiomem_instance *inst;
+
+static int exynos_gpiomem_open(struct inode *inode, struct file *file)
+{
+ int dev = iminor(inode);
+ int ret = 0;
+
+ dev_info(inst->dev, "gpiomem device opened.");
+
+ if (dev != DEVICE_MINOR) {
+ dev_err(inst->dev, "Unknown minor device: %d", dev);
+ ret = -ENXIO;
+ }
+ return ret;
+}
+
+static int exynos_gpiomem_release(struct inode *inode, struct file *file)
+{
+ int dev = iminor(inode);
+ int ret = 0;
+
+ if (dev != DEVICE_MINOR) {
+ dev_err(inst->dev, "Unknown minor device %d", dev);
+ ret = -ENXIO;
+ }
+ return ret;
+}
+
+static const struct vm_operations_struct exynos_gpiomem_vm_ops = {
+#ifdef CONFIG_HAVE_IOREMAP_PROT
+ .access = generic_access_phys
+#endif
+};
+
+static int exynos_gpiomem_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ int gpio_area = 0;
+
+ while (gpio_area < inst->gpio_area_count) {
+ if ((inst->gpio_regs_phys[gpio_area] >> PAGE_SHIFT) == vma->vm_pgoff)
+ goto found;
+
+ gpio_area++;
+ }
+
+ return -EACCES;
+
+found:
+ vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
+ PAGE_SIZE,
+ vma->vm_page_prot);
+
+ vma->vm_ops = &exynos_gpiomem_vm_ops;
+
+ if (remap_pfn_range(vma, vma->vm_start,
+ vma->vm_pgoff,
+ PAGE_SIZE,
+ vma->vm_page_prot)) {
+ return -EAGAIN;
+ }
+
+ return 0;
+}
+
+static const struct file_operations
+exynos_gpiomem_fops = {
+ .owner = THIS_MODULE,
+ .open = exynos_gpiomem_open,
+ .release = exynos_gpiomem_release,
+ .mmap = exynos_gpiomem_mmap,
+};
+
+static int exynos_gpiomem_probe(struct platform_device *pdev)
+{
+ int err = 0;
+ struct device *dev = &pdev->dev;
+ struct device_node *np = dev->of_node;
+ struct resource *res = NULL;
+ int i = 0;
+
+ /* Allocate buffers and instance data */
+ inst = kzalloc(sizeof(struct exynos_gpiomem_instance), GFP_KERNEL);
+
+ if (!inst) {
+ err = -ENOMEM;
+ goto failed_inst_alloc;
+ }
+
+ inst->dev = dev;
+
+ inst->gpio_area_count = of_property_count_elems_of_size(np, "reg",
+ sizeof(u32)) / 2;
+
+ if (inst->gpio_area_count > 32 || inst->gpio_area_count <= 0) {
+ dev_err(inst->dev, "failed to get gpio register area.");
+ err = -EINVAL;
+ goto failed_inst_alloc;
+ }
+
+ dev_info(inst->dev, "Initialised: GPIO register area is %d",
+ inst->gpio_area_count);
+
+ for (i = 0; i < inst->gpio_area_count; ++i) {
+ res = platform_get_resource(pdev, IORESOURCE_MEM, i);
+ if (res) {
+ inst->gpio_regs_phys[i] = res->start;
+ } else {
+ dev_err(inst->dev, "failed to get IO resource");
+ err = -ENOENT;
+ goto failed_get_resource;
+ }
+ }
+
+ /* Create character device entries */
+ err = alloc_chrdev_region(&exynos_gpiomem_devid,
+ DEVICE_MINOR, 1, DEVICE_NAME);
+ if (err != 0) {
+ dev_err(inst->dev, "unable to allocate device number");
+ goto failed_alloc_chrdev;
+ }
+ cdev_init(&exynos_gpiomem_cdev, &exynos_gpiomem_fops);
+ exynos_gpiomem_cdev.owner = THIS_MODULE;
+ err = cdev_add(&exynos_gpiomem_cdev, exynos_gpiomem_devid, 1);
+ if (err != 0) {
+ dev_err(inst->dev, "unable to register device");
+ goto failed_cdev_add;
+ }
+
+ /* Create sysfs entries */
+ exynos_gpiomem_class = class_create(THIS_MODULE, DEVICE_NAME);
+ err = IS_ERR(exynos_gpiomem_class);
+ if (err)
+ goto failed_class_create;
+
+ exynos_gpiomem_dev = device_create(exynos_gpiomem_class, NULL,
+ exynos_gpiomem_devid, NULL,
+ "gpiomem");
+ err = IS_ERR(exynos_gpiomem_dev);
+ if (err)
+ goto failed_device_create;
+
+ for (i = 0; i < inst->gpio_area_count; ++i) {
+ dev_info(inst->dev, "Initialised: Registers at 0x%08lx",
+ inst->gpio_regs_phys[i]);
+ }
+
+ return 0;
+
+failed_device_create:
+ class_destroy(exynos_gpiomem_class);
+failed_class_create:
+ cdev_del(&exynos_gpiomem_cdev);
+failed_cdev_add:
+ unregister_chrdev_region(exynos_gpiomem_devid, 1);
+failed_alloc_chrdev:
+failed_get_resource:
+ kfree(inst);
+failed_inst_alloc:
+ dev_err(inst->dev, "could not load exynos_gpiomem");
+ return err;
+}
+
+static int exynos_gpiomem_remove(struct platform_device *pdev)
+{
+ struct device *dev = inst->dev;
+
+ kfree(inst);
+ device_destroy(exynos_gpiomem_class, exynos_gpiomem_devid);
+ class_destroy(exynos_gpiomem_class);
+ cdev_del(&exynos_gpiomem_cdev);
+ unregister_chrdev_region(exynos_gpiomem_devid, 1);
+
+ dev_info(dev, "GPIO mem driver removed - OK");
+ return 0;
+}
+
+static const struct of_device_id exynos_gpiomem_of_match[] = {
+ {.compatible = "samsung,exynos-gpiomem",},
+ { },
+};
+MODULE_DEVICE_TABLE(of, exynos_gpiomem_of_match);
+
+static struct platform_driver exynos_gpiomem_driver = {
+ .driver = {
+ .name = DRIVER_NAME,
+ .owner = THIS_MODULE,
+ .of_match_table = exynos_gpiomem_of_match,
+ },
+ .probe = exynos_gpiomem_probe,
+ .remove = exynos_gpiomem_remove,
+};
+
+module_platform_driver(exynos_gpiomem_driver);
+
+MODULE_ALIAS("platform:gpiomem-exynos");
+MODULE_DESCRIPTION("EXYNOS gpiomem driver for accessing GPIO from userspace");
+MODULE_AUTHOR("Brian Kim <brian.kim@hardkernel.com>");
+MODULE_LICENSE("GPL");
--
2.25.1
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