drivers: char: add chardev for mmap'ing the RPiVid control registers

Based on the gpiomem driver, allow mapping of the decoder register
spaces such that userspace can access control/status registers.
This driver is intended for use with a custom ffmpeg backend accelerator
prior to a v4l2 driver being written.

Signed-off-by: Jonathan Bell <jonathan@raspberrypi.org>

arch/arm/boot/dts/bcm2838.dtsi

@@ -409,26 +409,26 @@
 		};
 
 		hevc-decoder@7eb00000 {
-			compatible = "raspberrypi,argon-hevc-decoder";
+			compatible = "raspberrypi,rpivid-hevc-decoder";
 			reg = <0x0 0x7eb00000 0x10000>;
 			status = "okay";
 		};
 
-		argon-local-intc@7eb10000 {
-			compatible = "raspberrypi,argon-local-intc";
+		rpivid-local-intc@7eb10000 {
+			compatible = "raspberrypi,rpivid-local-intc";
 			reg = <0x0 0x7eb10000 0x1000>;
 			status = "okay";
 			interrupts = <GIC_SPI 98 IRQ_TYPE_LEVEL_HIGH>;
 		};
 
 		h264-decoder@7eb20000 {
-			compatible = "raspberrypi,argon-h264-decoder";
+			compatible = "raspberrypi,rpivid-h264-decoder";
 			reg = <0x0 0x7eb20000 0x10000>;
 			status = "okay";
 		};
 
 		vp9-decoder@7eb30000 {
-			compatible = "raspberrypi,argon-vp9-decoder";
+			compatible = "raspberrypi,rpivid-vp9-decoder";
 			reg = <0x0 0x7eb30000 0x10000>;
 			status = "okay";
 		};

arch/arm/configs/bcm2711_defconfig

@@ -602,7 +602,7 @@ CONFIG_BRCM_CHAR_DRIVERS=y
 CONFIG_BCM_VCIO=y
 CONFIG_BCM_VC_SM=y
 CONFIG_BCM2835_DEVGPIOMEM=y
-CONFIG_ARGON_MEM=m
+CONFIG_RPIVID_MEM=m
 # CONFIG_LEGACY_PTYS is not set
 CONFIG_SERIAL_8250=y
 # CONFIG_SERIAL_8250_DEPRECATED_OPTIONS is not set

drivers/char/broadcom/Kconfig

@@ -49,3 +49,11 @@ config BCM2835_SMI_DEV
 		This driver provides a character device interface (ioctl + read/write) to
 		Broadcom's Secondary Memory interface. The low-level functionality is provided
 		by the SMI driver itself.
+
+config RPIVID_MEM
+	tristate "Character device driver for the Raspberry Pi RPIVid video decoder hardware"
+	default n
+	help
+		This driver provides a character device interface for memory-map operations
+		so userspace tools can access the control and status registers of the
+		Raspberry Pi RPiVid video decoder hardware.

drivers/char/broadcom/Makefile

@@ -4,3 +4,4 @@ obj-$(CONFIG_BCM_VC_SM)         += vc_sm/
 
 obj-$(CONFIG_BCM2835_DEVGPIOMEM)+= bcm2835-gpiomem.o
 obj-$(CONFIG_BCM2835_SMI_DEV)	+= bcm2835_smi_dev.o
+obj-$(CONFIG_RPIVID_MEM)	+= rpivid-mem.o

drivers/char/broadcom/rpivid-mem.c

@@ -0,0 +1,286 @@
+/**
+ * rpivid-mem.c - character device access to the RPiVid decoder registers
+ *
+ * Based on bcm2835-gpiomem.c. Provides IO memory access to the decoder
+ * register blocks such that ffmpeg plugins can access the hardware.
+ *
+ * Jonathan Bell <jonathan@raspberrypi.org>
+ * Copyright (c) 2019, 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/of_device.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>
+
+#define DRIVER_NAME "rpivid-mem"
+#define DEVICE_MINOR 0
+
+struct rpivid_mem_priv {
+	dev_t devid;
+	struct class *class;
+	struct cdev rpivid_mem_cdev;
+	unsigned long regs_phys;
+	unsigned long mem_window_len;
+	struct device *dev;
+	const char *name;
+};
+
+static int rpivid_mem_open(struct inode *inode, struct file *file)
+{
+	int dev = iminor(inode);
+	int ret = 0;
+	struct rpivid_mem_priv *priv;
+	if (dev != DEVICE_MINOR && dev != DEVICE_MINOR + 1)
+		ret = -ENXIO;
+
+	priv = container_of(inode->i_cdev, struct rpivid_mem_priv,
+				rpivid_mem_cdev);
+	if (!priv)
+		return -EINVAL;
+	file->private_data = priv;
+	return ret;
+}
+
+static int rpivid_mem_release(struct inode *inode, struct file *file)
+{
+	int dev = iminor(inode);
+	int ret = 0;
+
+	if (dev != DEVICE_MINOR && dev != DEVICE_MINOR + 1)
+		ret = -ENXIO;
+
+	return ret;
+}
+
+static const struct vm_operations_struct rpivid_mem_vm_ops = {
+#ifdef CONFIG_HAVE_IOREMAP_PROT
+	.access = generic_access_phys
+#endif
+};
+
+static int rpivid_mem_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct rpivid_mem_priv *priv;
+	unsigned long pages;
+
+	priv = file->private_data;
+	pages = priv->regs_phys >> PAGE_SHIFT;
+	/*
+	 * The address decode is far larger than the actual number of registers.
+	 * Just map the whole lot in.
+	 */
+	vma->vm_page_prot = phys_mem_access_prot(file, pages,
+						 priv->mem_window_len,
+						 vma->vm_page_prot);
+	vma->vm_ops = &rpivid_mem_vm_ops;
+	if (remap_pfn_range(vma, vma->vm_start,
+			pages,
+			priv->mem_window_len,
+			vma->vm_page_prot)) {
+		return -EAGAIN;
+	}
+	return 0;
+}
+
+static const struct file_operations
+rpivid_mem_fops = {
+	.owner = THIS_MODULE,
+	.open = rpivid_mem_open,
+	.release = rpivid_mem_release,
+	.mmap = rpivid_mem_mmap,
+};
+
+static const struct of_device_id rpivid_mem_of_match[];
+static int rpivid_mem_probe(struct platform_device *pdev)
+{
+	int err;
+	void *ptr_err;
+	const struct of_device_id *id;
+	struct device *dev = &pdev->dev;
+	struct device *rpivid_mem_dev;
+	struct resource *ioresource;
+	struct rpivid_mem_priv *priv;
+
+
+	/* Allocate buffers and instance data */
+
+	priv = kzalloc(sizeof(struct rpivid_mem_priv), GFP_KERNEL);
+
+	if (!priv) {
+		err = -ENOMEM;
+		goto failed_inst_alloc;
+	}
+	platform_set_drvdata(pdev, priv);
+
+	priv->dev = dev;
+	id = of_match_device(rpivid_mem_of_match, dev);
+	if (!id)
+		return -EINVAL;
+	priv->name = id->data;
+
+	ioresource = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (ioresource) {
+		priv->regs_phys = ioresource->start;
+		priv->mem_window_len = ioresource->end - ioresource->start;
+	} else {
+		dev_err(priv->dev, "failed to get IO resource");
+		err = -ENOENT;
+		goto failed_get_resource;
+	}
+
+	/* Create character device entries */
+
+	err = alloc_chrdev_region(&priv->devid,
+				  DEVICE_MINOR, 2, priv->name);
+	if (err != 0) {
+		dev_err(priv->dev, "unable to allocate device number");
+		goto failed_alloc_chrdev;
+	}
+	cdev_init(&priv->rpivid_mem_cdev, &rpivid_mem_fops);
+	priv->rpivid_mem_cdev.owner = THIS_MODULE;
+	err = cdev_add(&priv->rpivid_mem_cdev, priv->devid, 2);
+	if (err != 0) {
+		dev_err(priv->dev, "unable to register device");
+		goto failed_cdev_add;
+	}
+
+	/* Create sysfs entries */
+
+	priv->class = class_create(THIS_MODULE, priv->name);
+	ptr_err = priv->class;
+	if (IS_ERR(ptr_err))
+		goto failed_class_create;
+
+	rpivid_mem_dev = device_create(priv->class, NULL,
+					priv->devid, NULL,
+					priv->name);
+	ptr_err = rpivid_mem_dev;
+	if (IS_ERR(ptr_err))
+		goto failed_device_create;
+
+	/* Legacy alias */
+	{
+		char *oldname = kstrdup(priv->name, GFP_KERNEL);
+
+		oldname[1] = 'a';
+		oldname[2] = 'r';
+		oldname[3] = 'g';
+		oldname[4] = 'o';
+		oldname[5] = 'n';
+		(void)device_create(priv->class, NULL, priv->devid + 1, NULL,
+				       oldname + 1);
+		kfree(oldname);
+	}
+
+	dev_info(priv->dev, "%s initialised: Registers at 0x%08lx length 0x%08lx",
+		priv->name, priv->regs_phys, priv->mem_window_len);
+
+	return 0;
+
+failed_device_create:
+	class_destroy(priv->class);
+failed_class_create:
+	cdev_del(&priv->rpivid_mem_cdev);
+	err = PTR_ERR(ptr_err);
+failed_cdev_add:
+	unregister_chrdev_region(priv->devid, 1);
+failed_alloc_chrdev:
+failed_get_resource:
+	kfree(priv);
+failed_inst_alloc:
+	dev_err(priv->dev, "could not load rpivid_mem");
+	return err;
+}
+
+static int rpivid_mem_remove(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct rpivid_mem_priv *priv = platform_get_drvdata(pdev);
+
+	device_destroy(priv->class, priv->devid);
+	class_destroy(priv->class);
+	cdev_del(&priv->rpivid_mem_cdev);
+	unregister_chrdev_region(priv->devid, 1);
+	kfree(priv);
+
+	dev_info(dev, "%s driver removed - OK", priv->name);
+	return 0;
+}
+
+static const struct of_device_id rpivid_mem_of_match[] = {
+	{
+		.compatible = "raspberrypi,rpivid-hevc-decoder",
+		.data = "rpivid-hevcmem",
+	},
+	{
+		.compatible = "raspberrypi,rpivid-h264-decoder",
+		.data = "rpivid-h264mem",
+	},
+	{
+		.compatible = "raspberrypi,rpivid-vp9-decoder",
+		.data = "rpivid-vp9mem",
+	},
+	/* The "intc" is included as this block of hardware contains the
+	 * "frame done" status flags.
+	 */
+	{
+		.compatible = "raspberrypi,rpivid-local-intc",
+		.data = "rpivid-intcmem",
+	},
+	{ /* sentinel */ },
+};
+
+MODULE_DEVICE_TABLE(of, rpivid_mem_of_match);
+
+static struct platform_driver rpivid_mem_driver = {
+	.probe = rpivid_mem_probe,
+	.remove = rpivid_mem_remove,
+	.driver = {
+		   .name = DRIVER_NAME,
+		   .owner = THIS_MODULE,
+		   .of_match_table = rpivid_mem_of_match,
+		   },
+};
+
+module_platform_driver(rpivid_mem_driver);
+
+MODULE_ALIAS("platform:rpivid-mem");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Driver for accessing RPiVid decoder registers from userspace");
+MODULE_AUTHOR("Jonathan Bell <jonathan@raspberrypi.org>");

drivers/mfd/bcm2835-pm.c

@@ -50,14 +50,14 @@ static int bcm2835_pm_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	/* Map the ARGON ASB regs if present. */
+	/* Map the RPiVid ASB regs if present. */
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 2);
 	if (res) {
-		pm->arg_asb = devm_ioremap_resource(dev, res);
-		if (IS_ERR(pm->arg_asb)) {
-			dev_err(dev, "Failed to map ARGON ASB: %ld\n",
-				PTR_ERR(pm->arg_asb));
-			return PTR_ERR(pm->arg_asb);
+		pm->rpivid_asb = devm_ioremap_resource(dev, res);
+		if (IS_ERR(pm->rpivid_asb)) {
+			dev_err(dev, "Failed to map RPiVid ASB: %ld\n",
+				PTR_ERR(pm->rpivid_asb));
+			return PTR_ERR(pm->rpivid_asb);
 		}
 	}
 

drivers/soc/bcm/bcm2835-power.c

@@ -637,15 +637,15 @@ static int bcm2835_power_probe(struct platform_device *pdev)
 	power->base = pm->base;
 	power->asb = pm->asb;
 
-	/* 2711 hack: the new ARGON ASB took over V3D, which is our
+	/* 2711 hack: the new RPiVid ASB took over V3D, which is our
 	 * only consumer of this driver so far.  The old ASB seems to
 	 * still be present with ISP and H264 bits but no V3D, but I
 	 * don't know if that's real or not.  The V3D is in the same
 	 * place in the new ASB as the old one, so just poke the new
 	 * one for now.
 	 */
-	if (pm->arg_asb) {
-		power->asb = pm->arg_asb;
+	if (pm->rpivid_asb) {
+		power->asb = pm->rpivid_asb;
 		power->is_2711 = true;
 	}
 

include/linux/mfd/bcm2835-pm.h

@@ -9,7 +9,7 @@ struct bcm2835_pm {
 	struct device *dev;
 	void __iomem *base;
 	void __iomem *asb;
-	void __iomem *arg_asb;
+	void __iomem *rpivid_asb;
 };
 
 #endif /* BCM2835_MFD_PM_H */