soc: qcom: Remote filesystem memory driver

The Qualcomm remote file system protocol is used by certain remoteprocs,
in particular the modem, to read and write persistent storage in
platforms where only the application CPU has physical storage access.

The protocol is based on a set of QMI-encoded control-messages and a
shared memory buffer for exchaning the data. This driver implements the
latter, providing the user space service access to the carved out chunk
of memory.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>

drivers/of/platform.c

@@ -498,6 +498,7 @@ EXPORT_SYMBOL_GPL(of_platform_default_populate);
 
 #ifndef CONFIG_PPC
 static const struct of_device_id reserved_mem_matches[] = {
+	{ .compatible = "qcom,rmtfs-mem" },
 	{ .compatible = "ramoops" },
 	{}
 };

drivers/soc/qcom/Kconfig

@@ -35,6 +35,17 @@ config QCOM_PM
 	  modes. It interface with various system drivers to put the cores in
 	  low power modes.
 
+config QCOM_RMTFS_MEM
+	tristate "Qualcomm Remote Filesystem memory driver"
+	depends on ARCH_QCOM
+	help
+	  The Qualcomm remote filesystem memory driver is used for allocating
+	  and exposing regions of shared memory with remote processors for the
+	  purpose of exchanging sector-data between the remote filesystem
+	  service and its clients.
+
+	  Say y here if you intend to boot the modem remoteproc.
+
 config QCOM_SMEM
 	tristate "Qualcomm Shared Memory Manager (SMEM)"
 	depends on ARCH_QCOM

drivers/soc/qcom/Makefile

@@ -2,6 +2,7 @@ obj-$(CONFIG_QCOM_GLINK_SSR) +=	glink_ssr.o
 obj-$(CONFIG_QCOM_GSBI)	+=	qcom_gsbi.o
 obj-$(CONFIG_QCOM_MDT_LOADER)	+= mdt_loader.o
 obj-$(CONFIG_QCOM_PM)	+=	spm.o
+obj-$(CONFIG_QCOM_RMTFS_MEM)	+= rmtfs_mem.o
 obj-$(CONFIG_QCOM_SMD_RPM)	+= smd-rpm.o
 obj-$(CONFIG_QCOM_SMEM) +=	smem.o
 obj-$(CONFIG_QCOM_SMEM_STATE) += smem_state.o

drivers/soc/qcom/rmtfs_mem.c

@@ -0,0 +1,271 @@
+/*
+ * Copyright (c) 2017 Linaro Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/cdev.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/of_reserved_mem.h>
+#include <linux/dma-mapping.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/io.h>
+#include <linux/qcom_scm.h>
+
+#define QCOM_RMTFS_MEM_DEV_MAX	(MINORMASK + 1)
+
+static dev_t qcom_rmtfs_mem_major;
+
+struct qcom_rmtfs_mem {
+	struct device dev;
+	struct cdev cdev;
+
+	void *base;
+	phys_addr_t addr;
+	phys_addr_t size;
+
+	unsigned int client_id;
+};
+
+static ssize_t qcom_rmtfs_mem_show(struct device *dev,
+			      struct device_attribute *attr,
+			      char *buf);
+
+static DEVICE_ATTR(phys_addr, 0400, qcom_rmtfs_mem_show, NULL);
+static DEVICE_ATTR(size, 0400, qcom_rmtfs_mem_show, NULL);
+static DEVICE_ATTR(client_id, 0400, qcom_rmtfs_mem_show, NULL);
+
+static ssize_t qcom_rmtfs_mem_show(struct device *dev,
+			      struct device_attribute *attr,
+			      char *buf)
+{
+	struct qcom_rmtfs_mem *rmtfs_mem = container_of(dev,
+							struct qcom_rmtfs_mem,
+							dev);
+
+	if (attr == &dev_attr_phys_addr)
+		return sprintf(buf, "%pa\n", &rmtfs_mem->addr);
+	if (attr == &dev_attr_size)
+		return sprintf(buf, "%pa\n", &rmtfs_mem->size);
+	if (attr == &dev_attr_client_id)
+		return sprintf(buf, "%d\n", rmtfs_mem->client_id);
+
+	return -EINVAL;
+}
+
+static struct attribute *qcom_rmtfs_mem_attrs[] = {
+	&dev_attr_phys_addr.attr,
+	&dev_attr_size.attr,
+	&dev_attr_client_id.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(qcom_rmtfs_mem);
+
+static int qcom_rmtfs_mem_open(struct inode *inode, struct file *filp)
+{
+	struct qcom_rmtfs_mem *rmtfs_mem = container_of(inode->i_cdev,
+							struct qcom_rmtfs_mem,
+							cdev);
+
+	get_device(&rmtfs_mem->dev);
+	filp->private_data = rmtfs_mem;
+
+	return 0;
+}
+static ssize_t qcom_rmtfs_mem_read(struct file *filp,
+			      char __user *buf, size_t count, loff_t *f_pos)
+{
+	struct qcom_rmtfs_mem *rmtfs_mem = filp->private_data;
+
+	if (*f_pos >= rmtfs_mem->size)
+		return 0;
+
+	if (*f_pos + count >= rmtfs_mem->size)
+		count = rmtfs_mem->size - *f_pos;
+
+	if (copy_to_user(buf, rmtfs_mem->base + *f_pos, count))
+		return -EFAULT;
+
+	*f_pos += count;
+	return count;
+}
+
+static ssize_t qcom_rmtfs_mem_write(struct file *filp,
+			       const char __user *buf, size_t count,
+			       loff_t *f_pos)
+{
+	struct qcom_rmtfs_mem *rmtfs_mem = filp->private_data;
+
+	if (*f_pos >= rmtfs_mem->size)
+		return 0;
+
+	if (*f_pos + count >= rmtfs_mem->size)
+		count = rmtfs_mem->size - *f_pos;
+
+	if (copy_from_user(rmtfs_mem->base + *f_pos, buf, count))
+		return -EFAULT;
+
+	*f_pos += count;
+	return count;
+}
+
+static int qcom_rmtfs_mem_release(struct inode *inode, struct file *filp)
+{
+	struct qcom_rmtfs_mem *rmtfs_mem = filp->private_data;
+
+	put_device(&rmtfs_mem->dev);
+
+	return 0;
+}
+
+static const struct file_operations qcom_rmtfs_mem_fops = {
+	.owner = THIS_MODULE,
+	.open = qcom_rmtfs_mem_open,
+	.read = qcom_rmtfs_mem_read,
+	.write = qcom_rmtfs_mem_write,
+	.release = qcom_rmtfs_mem_release,
+	.llseek = default_llseek,
+};
+
+static void qcom_rmtfs_mem_release_device(struct device *dev)
+{
+	struct qcom_rmtfs_mem *rmtfs_mem = container_of(dev,
+							struct qcom_rmtfs_mem,
+							dev);
+
+	kfree(rmtfs_mem);
+}
+
+static int qcom_rmtfs_mem_probe(struct platform_device *pdev)
+{
+	struct device_node *node = pdev->dev.of_node;
+	struct reserved_mem *rmem;
+	struct qcom_rmtfs_mem *rmtfs_mem;
+	u32 client_id;
+	int ret;
+
+	rmem = of_reserved_mem_lookup(node);
+	if (!rmem) {
+		dev_err(&pdev->dev, "failed to acquire memory region\n");
+		return -EINVAL;
+	}
+
+	ret = of_property_read_u32(node, "qcom,client-id", &client_id);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to parse \"qcom,client-id\"\n");
+		return ret;
+
+	}
+
+	rmtfs_mem = kzalloc(sizeof(*rmtfs_mem), GFP_KERNEL);
+	if (!rmtfs_mem)
+		return -ENOMEM;
+
+	rmtfs_mem->addr = rmem->base;
+	rmtfs_mem->client_id = client_id;
+	rmtfs_mem->size = rmem->size;
+
+	device_initialize(&rmtfs_mem->dev);
+	rmtfs_mem->dev.parent = &pdev->dev;
+	rmtfs_mem->dev.groups = qcom_rmtfs_mem_groups;
+
+	rmtfs_mem->base = devm_memremap(&rmtfs_mem->dev, rmtfs_mem->addr,
+					rmtfs_mem->size, MEMREMAP_WC);
+	if (IS_ERR(rmtfs_mem->base)) {
+		dev_err(&pdev->dev, "failed to remap rmtfs_mem region\n");
+		ret = PTR_ERR(rmtfs_mem->base);
+		goto put_device;
+	}
+
+	cdev_init(&rmtfs_mem->cdev, &qcom_rmtfs_mem_fops);
+	rmtfs_mem->cdev.owner = THIS_MODULE;
+
+	dev_set_name(&rmtfs_mem->dev, "qcom_rmtfs_mem%d", client_id);
+	rmtfs_mem->dev.id = client_id;
+	rmtfs_mem->dev.devt = MKDEV(MAJOR(qcom_rmtfs_mem_major), client_id);
+
+	ret = cdev_device_add(&rmtfs_mem->cdev, &rmtfs_mem->dev);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to add cdev: %d\n", ret);
+		goto put_device;
+	}
+
+	rmtfs_mem->dev.release = qcom_rmtfs_mem_release_device;
+
+	dev_set_drvdata(&pdev->dev, rmtfs_mem);
+
+	return 0;
+
+remove_cdev:
+	cdev_device_del(&rmtfs_mem->cdev, &rmtfs_mem->dev);
+put_device:
+	put_device(&rmtfs_mem->dev);
+
+	return ret;
+}
+
+static int qcom_rmtfs_mem_remove(struct platform_device *pdev)
+{
+	struct qcom_rmtfs_mem *rmtfs_mem = dev_get_drvdata(&pdev->dev);
+
+	cdev_device_del(&rmtfs_mem->cdev, &rmtfs_mem->dev);
+	put_device(&rmtfs_mem->dev);
+
+	return 0;
+}
+
+static const struct of_device_id qcom_rmtfs_mem_of_match[] = {
+	{ .compatible = "qcom,rmtfs-mem" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, qcom_rmtfs_mem_of_match);
+
+static struct platform_driver qcom_rmtfs_mem_driver = {
+	.probe = qcom_rmtfs_mem_probe,
+	.remove = qcom_rmtfs_mem_remove,
+	.driver  = {
+		.name  = "qcom_rmtfs_mem",
+		.of_match_table = qcom_rmtfs_mem_of_match,
+	},
+};
+
+static int qcom_rmtfs_mem_init(void)
+{
+	int ret;
+
+	ret = alloc_chrdev_region(&qcom_rmtfs_mem_major, 0,
+				  QCOM_RMTFS_MEM_DEV_MAX, "qcom_rmtfs_mem");
+	if (ret < 0) {
+		pr_err("qcom_rmtfs_mem: failed to allocate char dev region\n");
+		return ret;
+	}
+
+	ret = platform_driver_register(&qcom_rmtfs_mem_driver);
+	if (ret < 0) {
+		pr_err("qcom_rmtfs_mem: failed to register rmtfs_mem driver\n");
+		unregister_chrdev_region(qcom_rmtfs_mem_major,
+					 QCOM_RMTFS_MEM_DEV_MAX);
+	}
+
+	return ret;
+}
+module_init(qcom_rmtfs_mem_init);
+
+static void qcom_rmtfs_mem_exit(void)
+{
+	platform_driver_unregister(&qcom_rmtfs_mem_driver);
+	unregister_chrdev_region(qcom_rmtfs_mem_major, QCOM_RMTFS_MEM_DEV_MAX);
+}
+module_exit(qcom_rmtfs_mem_exit);