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+/*
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+ * rcar-fcp.c -- R-Car Frame Compression Processor Driver
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+ *
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+ * Copyright (C) 2016 Renesas Electronics Corporation
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+ *
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+ * Contact: Laurent Pinchart (laurent.pinchart@ideasonboard.com)
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+ *
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+ * This program is free software; you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License as published by
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+ * the Free Software Foundation; either version 2 of the License, or
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+ * (at your option) any later version.
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+ */
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+
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+#include <linux/device.h>
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+#include <linux/list.h>
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+#include <linux/module.h>
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+#include <linux/mutex.h>
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+#include <linux/platform_device.h>
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+#include <linux/pm_runtime.h>
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+#include <linux/slab.h>
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+
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+#include <media/rcar-fcp.h>
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+
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+struct rcar_fcp_device {
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+ struct list_head list;
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+ struct device *dev;
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+};
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+
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+static LIST_HEAD(fcp_devices);
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+static DEFINE_MUTEX(fcp_lock);
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+
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+/* -----------------------------------------------------------------------------
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+ * Public API
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+ */
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+
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+/**
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+ * rcar_fcp_get - Find and acquire a reference to an FCP instance
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+ * @np: Device node of the FCP instance
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+ *
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+ * Search the list of registered FCP instances for the instance corresponding to
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+ * the given device node.
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+ *
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+ * Return a pointer to the FCP instance, or an ERR_PTR if the instance can't be
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+ * found.
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+ */
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+struct rcar_fcp_device *rcar_fcp_get(const struct device_node *np)
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+{
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+ struct rcar_fcp_device *fcp;
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+
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+ mutex_lock(&fcp_lock);
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+
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+ list_for_each_entry(fcp, &fcp_devices, list) {
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+ if (fcp->dev->of_node != np)
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+ continue;
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+
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+ /*
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+ * Make sure the module won't be unloaded behind our back. This
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+ * is a poor man's safety net, the module should really not be
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+ * unloaded while FCP users can be active.
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+ */
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+ if (!try_module_get(fcp->dev->driver->owner))
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+ fcp = NULL;
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+
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+ goto done;
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+ }
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+
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+ fcp = ERR_PTR(-EPROBE_DEFER);
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+
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+done:
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+ mutex_unlock(&fcp_lock);
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+ return fcp;
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+}
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+EXPORT_SYMBOL_GPL(rcar_fcp_get);
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+
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+/**
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+ * rcar_fcp_put - Release a reference to an FCP instance
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+ * @fcp: The FCP instance
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+ *
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+ * Release the FCP instance acquired by a call to rcar_fcp_get().
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+ */
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+void rcar_fcp_put(struct rcar_fcp_device *fcp)
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+{
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+ if (fcp)
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+ module_put(fcp->dev->driver->owner);
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+}
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+EXPORT_SYMBOL_GPL(rcar_fcp_put);
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+
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+/**
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+ * rcar_fcp_enable - Enable an FCP
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+ * @fcp: The FCP instance
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+ *
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+ * Before any memory access through an FCP is performed by a module, the FCP
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+ * must be enabled by a call to this function. The enable calls are reference
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+ * counted, each successful call must be followed by one rcar_fcp_disable()
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+ * call when no more memory transfer can occur through the FCP.
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+ *
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+ * Return 0 on success or a negative error code if an error occurs. The enable
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+ * reference count isn't increased when this function returns an error.
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+ */
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+int rcar_fcp_enable(struct rcar_fcp_device *fcp)
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+{
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+ if (!fcp)
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+ return 0;
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+
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+ return pm_runtime_get_sync(fcp->dev);
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+}
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+EXPORT_SYMBOL_GPL(rcar_fcp_enable);
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+
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+/**
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+ * rcar_fcp_disable - Disable an FCP
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+ * @fcp: The FCP instance
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+ *
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+ * This function is the counterpart of rcar_fcp_enable(). As enable calls are
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+ * reference counted a disable call may not disable the FCP synchronously.
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+ */
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+void rcar_fcp_disable(struct rcar_fcp_device *fcp)
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+{
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+ if (fcp)
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+ pm_runtime_put(fcp->dev);
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+}
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+EXPORT_SYMBOL_GPL(rcar_fcp_disable);
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+
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+/* -----------------------------------------------------------------------------
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+ * Platform Driver
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+ */
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+
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+static int rcar_fcp_probe(struct platform_device *pdev)
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+{
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+ struct rcar_fcp_device *fcp;
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+
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+ fcp = devm_kzalloc(&pdev->dev, sizeof(*fcp), GFP_KERNEL);
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+ if (fcp == NULL)
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+ return -ENOMEM;
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+
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+ fcp->dev = &pdev->dev;
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+
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+ pm_runtime_enable(&pdev->dev);
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+
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+ mutex_lock(&fcp_lock);
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+ list_add_tail(&fcp->list, &fcp_devices);
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+ mutex_unlock(&fcp_lock);
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+
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+ platform_set_drvdata(pdev, fcp);
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+
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+ return 0;
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+}
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+
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+static int rcar_fcp_remove(struct platform_device *pdev)
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+{
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+ struct rcar_fcp_device *fcp = platform_get_drvdata(pdev);
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+
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+ mutex_lock(&fcp_lock);
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+ list_del(&fcp->list);
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+ mutex_unlock(&fcp_lock);
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+
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+ pm_runtime_disable(&pdev->dev);
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+
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+ return 0;
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+}
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+
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+static const struct of_device_id rcar_fcp_of_match[] = {
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+ { .compatible = "renesas,fcpv" },
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+ { },
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+};
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+
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+static struct platform_driver rcar_fcp_platform_driver = {
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+ .probe = rcar_fcp_probe,
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+ .remove = rcar_fcp_remove,
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+ .driver = {
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+ .name = "rcar-fcp",
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+ .of_match_table = rcar_fcp_of_match,
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+ .suppress_bind_attrs = true,
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+ },
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+};
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+
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+module_platform_driver(rcar_fcp_platform_driver);
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+
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+MODULE_ALIAS("rcar-fcp");
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+MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
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+MODULE_DESCRIPTION("Renesas FCP Driver");
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+MODULE_LICENSE("GPL");
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Laurent Pinchart