ODROID-COMMON:Add /dev/gpiomem device for rootless user GPIO access
Change-Id: I559e9155294144372d64a8b79044ea53318c4e0a
diff --git a/MAINTAINERS b/MAINTAINERS
index 47bf549..8c3b581 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14727,3 +14727,7 @@
M: codewalker@hardkernel.com>
S: Maintained
F: drivers/input/touchscreen/dwav-usb-mt.c
+
+HARDKERNEL S922D odroidn2
+M: Kevin Kim <ckkim@hardkernel.com>
+F: drivers/char/aml-gpiomem.c
diff --git a/arch/arm64/boot/dts/amlogic/mesong12_odroid_common.dtsi b/arch/arm64/boot/dts/amlogic/mesong12_odroid_common.dtsi
index 6f4327b..a46f5a2 100644
--- a/arch/arm64/boot/dts/amlogic/mesong12_odroid_common.dtsi
+++ b/arch/arm64/boot/dts/amlogic/mesong12_odroid_common.dtsi
@@ -31,6 +31,12 @@
tsensor1 = &d_tsensor;
};
+ gpiomem {
+ compatible = "amlogic, gpiomem";
+ reg = <0x0 0xff634000 0x0 0x1000>;
+ status = "okay";
+ };
+
codec_mm {
compatible = "amlogic, codec, mm";
memory-region = <&codec_mm_cma &codec_mm_reserved>;
diff --git a/arch/arm64/configs/odroidn2_defconfig b/arch/arm64/configs/odroidn2_defconfig
index acb6fd0..cc29de8 100644
--- a/arch/arm64/configs/odroidn2_defconfig
+++ b/arch/arm64/configs/odroidn2_defconfig
@@ -2304,6 +2304,7 @@
# CONFIG_RAW_DRIVER is not set
# CONFIG_TCG_TPM is not set
# CONFIG_XILLYBUS is not set
+CONFIG_AMLOGIC_GPIOMEM=y
#
# I2C support
diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index 8453a49..41aa9fd 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -593,5 +593,14 @@
source "drivers/char/xillybus/Kconfig"
+config AMLOGIC_GPIOMEM
+ tristate "/dev/gpiomem rootless GPIO access via mmap() on the Amlogic"
+ default m
+ ---help---
+ Provides users with root-free access to the GPIO registers
+ on Meson g12 platform. 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
diff --git a/drivers/char/Makefile b/drivers/char/Makefile
index 6e6c244..65f5ad4 100644
--- a/drivers/char/Makefile
+++ b/drivers/char/Makefile
@@ -60,3 +60,5 @@
obj-$(CONFIG_TILE_SROM) += tile-srom.o
obj-$(CONFIG_XILLYBUS) += xillybus/
obj-$(CONFIG_POWERNV_OP_PANEL) += powernv-op-panel.o
+
+obj-$(CONFIG_AMLOGIC_GPIOMEM) += aml-gpiomem.o
diff --git a/drivers/char/aml-gpiomem.c b/drivers/char/aml-gpiomem.c
new file mode 100644
index 0000000..566b07c
--- /dev/null
+++ b/drivers/char/aml-gpiomem.c
@@ -0,0 +1,235 @@
+/*
+ * linux/drivers/char/aml-gpiomem.c
+ *
+ * GPIO memory device driver
+ *
+ * Creates a chardev /dev/gpiomem which will provide user access to
+ * the Meson g12 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/platform_device.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/cdev.h>
+#include <linux/pagemap.h>
+
+#define DEVICE_NAME "aml-gpiomem"
+#define DRIVER_NAME "gpiomem-aml"
+#define DEVICE_MINOR 0
+
+struct aml_gpiomem_instance {
+ unsigned long gpio_regs_phys;
+ struct device *dev;
+};
+
+static struct cdev aml_gpiomem_cdev;
+static dev_t aml_gpiomem_devid;
+static struct class *aml_gpiomem_class;
+static struct device *aml_gpiomem_dev;
+static struct aml_gpiomem_instance *inst;
+
+static int aml_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 aml_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 aml_gpiomem_vm_ops = {
+#ifdef CONFIG_HAVE_IOREMAP_PROT
+ .access = generic_access_phys
+#endif
+};
+
+static int aml_gpiomem_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ unsigned long gpio_page = inst->gpio_regs_phys >> PAGE_SHIFT;
+
+ vma->vm_page_prot = phys_mem_access_prot(file, gpio_page,
+ PAGE_SIZE,
+ vma->vm_page_prot);
+
+ vma->vm_ops = &aml_gpiomem_vm_ops;
+ if (remap_pfn_range(vma, vma->vm_start,
+ gpio_page,
+ PAGE_SIZE,
+ vma->vm_page_prot)) {
+ return -EAGAIN;
+ }
+
+ return 0;
+}
+
+static const struct file_operations
+aml_gpiomem_fops = {
+ .owner = THIS_MODULE,
+ .open = aml_gpiomem_open,
+ .release = aml_gpiomem_release,
+ .mmap = aml_gpiomem_mmap,
+};
+
+static int aml_gpiomem_probe(struct platform_device *pdev)
+{
+ int err = 0;
+ struct device *dev = &pdev->dev;
+ struct resource *res = NULL;
+
+ /* Allocate buffers and instance data */
+ inst = kzalloc(sizeof(struct aml_gpiomem_instance), GFP_KERNEL);
+ if (!inst) {
+ err = -ENOMEM;
+ goto failed_inst_alloc;
+ }
+
+ inst->dev = dev;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (res) {
+ inst->gpio_regs_phys = 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(&aml_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(&aml_gpiomem_cdev, &aml_gpiomem_fops);
+ aml_gpiomem_cdev.owner = THIS_MODULE;
+ err = cdev_add(&aml_gpiomem_cdev, aml_gpiomem_devid, 1);
+ if (err != 0) {
+ dev_err(inst->dev, "unable to register device");
+ goto failed_cdev_add;
+ }
+
+ /* Create sysfs entries */
+ aml_gpiomem_class = class_create(THIS_MODULE, DEVICE_NAME);
+ err = IS_ERR(aml_gpiomem_class);
+ if (err)
+ goto failed_class_create;
+
+ aml_gpiomem_dev = device_create(aml_gpiomem_class, NULL,
+ aml_gpiomem_devid, NULL,
+ "gpiomem");
+ err = IS_ERR(aml_gpiomem_dev);
+ if (err)
+ goto failed_device_create;
+
+ dev_info(inst->dev, "Initialised: Registers at 0x%08lx",
+ inst->gpio_regs_phys);
+
+ return 0;
+
+failed_device_create:
+ class_destroy(aml_gpiomem_class);
+failed_class_create:
+ cdev_del(&aml_gpiomem_cdev);
+failed_cdev_add:
+ unregister_chrdev_region(aml_gpiomem_devid, 1);
+failed_alloc_chrdev:
+failed_get_resource:
+ kfree(inst);
+failed_inst_alloc:
+ dev_err(inst->dev, "could not load aml_gpiomem");
+ return err;
+}
+
+static int aml_gpiomem_remove(struct platform_device *pdev)
+{
+ struct device *dev = inst->dev;
+
+ kfree(inst);
+ device_destroy(aml_gpiomem_class, aml_gpiomem_devid);
+ class_destroy(aml_gpiomem_class);
+ cdev_del(&aml_gpiomem_cdev);
+ unregister_chrdev_region(aml_gpiomem_devid, 1);
+
+ dev_info(dev, "GPIO mem driver removed - OK");
+ return 0;
+}
+
+static const struct of_device_id aml_gpiomem_of_match[] = {
+ {.compatible = "amlogic, gpiomem",},
+ { },
+};
+MODULE_DEVICE_TABLE(of, aml_gpiomem_of_match);
+
+static struct platform_driver aml_gpiomem_driver = {
+ .driver = {
+ .name = DRIVER_NAME,
+ .owner = THIS_MODULE,
+ .of_match_table = aml_gpiomem_of_match,
+ },
+ .probe = aml_gpiomem_probe,
+ .remove = aml_gpiomem_remove,
+};
+
+module_platform_driver(aml_gpiomem_driver);
+
+MODULE_ALIAS("platform:gpiomem-aml");
+MODULE_DESCRIPTION("AMLogic gpiomem driver for accessing GPIO from userspace");
+MODULE_AUTHOR("Brian Kim <brian.kim@hardkernel.com>");
+MODULE_LICENSE("GPL");