Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

4 files changed, 653 insertions, 0 deletions

diff --git a/drivers/soc/sunxi/Kconfig b/drivers/soc/sunxi/Kconfig
new file mode 100644
index 000000000..8aecbc9b1
--- /dev/null
+++ b/drivers/soc/sunxi/Kconfig
@@ -0,0 +1,21 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Allwinner sunXi SoC drivers
+#
+
+config SUNXI_MBUS
+	bool
+	default ARCH_SUNXI
+	depends on ARM || ARM64
+	help
+	  Say y to enable the fixups needed to support the Allwinner
+	  MBUS DMA quirks.
+
+config SUNXI_SRAM
+	bool
+	default ARCH_SUNXI
+	select REGMAP_MMIO
+	help
+	  Say y here to enable the SRAM controller support. This
+	  device is responsible on mapping the SRAM in the sunXi SoCs
+	  whether to the CPU/DMA, or to the devices.
diff --git a/drivers/soc/sunxi/Makefile b/drivers/soc/sunxi/Makefile
new file mode 100644
index 000000000..549159571
--- /dev/null
+++ b/drivers/soc/sunxi/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_SUNXI_MBUS) +=	sunxi_mbus.o
+obj-$(CONFIG_SUNXI_SRAM) +=	sunxi_sram.o
diff --git a/drivers/soc/sunxi/sunxi_mbus.c b/drivers/soc/sunxi/sunxi_mbus.c
new file mode 100644
index 000000000..8bc5f62ff
--- /dev/null
+++ b/drivers/soc/sunxi/sunxi_mbus.c
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2020 Maxime Ripard <maxime@cerno.tech> */
+
+#include <linux/device.h>
+#include <linux/dma-map-ops.h>
+#include <linux/init.h>
+#include <linux/notifier.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+static const char * const sunxi_mbus_devices[] = {
+	/*
+	 * The display engine virtual devices are not strictly speaking
+	 * connected to the MBUS, but since DRM will perform all the
+	 * memory allocations and DMA operations through that device, we
+	 * need to have the quirk on those devices too.
+	 */
+	"allwinner,sun4i-a10-display-engine",
+	"allwinner,sun5i-a10s-display-engine",
+	"allwinner,sun5i-a13-display-engine",
+	"allwinner,sun6i-a31-display-engine",
+	"allwinner,sun6i-a31s-display-engine",
+	"allwinner,sun7i-a20-display-engine",
+	"allwinner,sun8i-a23-display-engine",
+	"allwinner,sun8i-a33-display-engine",
+	"allwinner,sun9i-a80-display-engine",
+
+	/*
+	 * And now we have the regular devices connected to the MBUS
+	 * (that we know of).
+	 */
+	"allwinner,sun4i-a10-csi1",
+	"allwinner,sun4i-a10-display-backend",
+	"allwinner,sun4i-a10-display-frontend",
+	"allwinner,sun4i-a10-video-engine",
+	"allwinner,sun5i-a13-display-backend",
+	"allwinner,sun5i-a13-video-engine",
+	"allwinner,sun6i-a31-csi",
+	"allwinner,sun6i-a31-display-backend",
+	"allwinner,sun7i-a20-csi0",
+	"allwinner,sun7i-a20-display-backend",
+	"allwinner,sun7i-a20-display-frontend",
+	"allwinner,sun7i-a20-video-engine",
+	"allwinner,sun8i-a23-display-backend",
+	"allwinner,sun8i-a23-display-frontend",
+	"allwinner,sun8i-a33-display-backend",
+	"allwinner,sun8i-a33-display-frontend",
+	"allwinner,sun8i-a33-video-engine",
+	"allwinner,sun8i-a83t-csi",
+	"allwinner,sun8i-h3-csi",
+	"allwinner,sun8i-h3-video-engine",
+	"allwinner,sun8i-v3s-csi",
+	"allwinner,sun9i-a80-display-backend",
+	"allwinner,sun50i-a64-csi",
+	"allwinner,sun50i-a64-video-engine",
+	"allwinner,sun50i-h5-video-engine",
+	NULL,
+};
+
+static int sunxi_mbus_notifier(struct notifier_block *nb,
+			       unsigned long event, void *__dev)
+{
+	struct device *dev = __dev;
+	int ret;
+
+	if (event != BUS_NOTIFY_ADD_DEVICE)
+		return NOTIFY_DONE;
+
+	/*
+	 * Only the devices that need a large memory bandwidth do DMA
+	 * directly over the memory bus (called MBUS), instead of going
+	 * through the regular system bus.
+	 */
+	if (!of_device_compatible_match(dev->of_node, sunxi_mbus_devices))
+		return NOTIFY_DONE;
+
+	/*
+	 * Devices with an interconnects property have the MBUS
+	 * relationship described in their DT and dealt with by
+	 * of_dma_configure, so we can just skip them.
+	 *
+	 * Older DTs or SoCs who are not clearly understood need to set
+	 * that DMA offset though.
+	 */
+	if (of_property_present(dev->of_node, "interconnects"))
+		return NOTIFY_DONE;
+
+	ret = dma_direct_set_offset(dev, PHYS_OFFSET, 0, SZ_4G);
+	if (ret)
+		dev_err(dev, "Couldn't setup our DMA offset: %d\n", ret);
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block sunxi_mbus_nb = {
+	.notifier_call = sunxi_mbus_notifier,
+};
+
+static const char * const sunxi_mbus_platforms[] __initconst = {
+	"allwinner,sun4i-a10",
+	"allwinner,sun5i-a10s",
+	"allwinner,sun5i-a13",
+	"allwinner,sun6i-a31",
+	"allwinner,sun7i-a20",
+	"allwinner,sun8i-a23",
+	"allwinner,sun8i-a33",
+	"allwinner,sun8i-a83t",
+	"allwinner,sun8i-h3",
+	"allwinner,sun8i-r40",
+	"allwinner,sun8i-v3",
+	"allwinner,sun8i-v3s",
+	"allwinner,sun9i-a80",
+	"allwinner,sun50i-a64",
+	"allwinner,sun50i-h5",
+	"nextthing,gr8",
+	NULL,
+};
+
+static int __init sunxi_mbus_init(void)
+{
+	if (!of_machine_compatible_match(sunxi_mbus_platforms))
+		return 0;
+
+	bus_register_notifier(&platform_bus_type, &sunxi_mbus_nb);
+	return 0;
+}
+arch_initcall(sunxi_mbus_init);
diff --git a/drivers/soc/sunxi/sunxi_sram.c b/drivers/soc/sunxi/sunxi_sram.c
new file mode 100644
index 000000000..2ccaeacf8
--- /dev/null
+++ b/drivers/soc/sunxi/sunxi_sram.c
@@ -0,0 +1,502 @@
+/*
+ * Allwinner SoCs SRAM Controller Driver
+ *
+ * Copyright (C) 2015 Maxime Ripard
+ *
+ * Author: Maxime Ripard <maxime.ripard@free-electrons.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/debugfs.h>
+#include <linux/io.h>
+#include <linux/limits.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#include <linux/soc/sunxi/sunxi_sram.h>
+
+struct sunxi_sram_func {
+	char	*func;
+	u8	val;
+	u32	reg_val;
+};
+
+struct sunxi_sram_data {
+	char				*name;
+	u8				reg;
+	u8				offset;
+	u8				width;
+	const struct sunxi_sram_func	*func;
+};
+
+struct sunxi_sram_desc {
+	struct sunxi_sram_data	data;
+	u8			claim_cnt;
+};
+
+#define SUNXI_SRAM_MAP(_reg_val, _val, _func)			\
+	{							\
+		.func = _func,					\
+		.val = _val,					\
+		.reg_val = _reg_val,				\
+	}
+
+#define SUNXI_SRAM_DATA(_name, _reg, _off, _width, ...)		\
+	{							\
+		.name = _name,					\
+		.reg = _reg,					\
+		.offset = _off,					\
+		.width = _width,				\
+		.func = (const struct sunxi_sram_func[]){	\
+			__VA_ARGS__, { } },			\
+	}
+
+static struct sunxi_sram_desc sun4i_a10_sram_a3_a4 = {
+	.data	= SUNXI_SRAM_DATA("A3-A4", 0x4, 0x4, 2,
+				  SUNXI_SRAM_MAP(0, 0, "cpu"),
+				  SUNXI_SRAM_MAP(1, 1, "emac")),
+};
+
+static struct sunxi_sram_desc sun4i_a10_sram_c1 = {
+	.data	= SUNXI_SRAM_DATA("C1", 0x0, 0x0, 31,
+				  SUNXI_SRAM_MAP(0, 0, "cpu"),
+				  SUNXI_SRAM_MAP(0x7fffffff, 1, "ve")),
+};
+
+static struct sunxi_sram_desc sun4i_a10_sram_d = {
+	.data	= SUNXI_SRAM_DATA("D", 0x4, 0x0, 1,
+				  SUNXI_SRAM_MAP(0, 0, "cpu"),
+				  SUNXI_SRAM_MAP(1, 1, "usb-otg")),
+};
+
+static struct sunxi_sram_desc sun50i_a64_sram_c = {
+	.data	= SUNXI_SRAM_DATA("C", 0x4, 24, 1,
+				  SUNXI_SRAM_MAP(1, 0, "cpu"),
+				  SUNXI_SRAM_MAP(0, 1, "de2")),
+};
+
+static struct sunxi_sram_desc sun50i_h616_ve_sram = {
+	.data	= SUNXI_SRAM_DATA("VE", 0x0, 0, 1,
+				  SUNXI_SRAM_MAP(1, 0, "cpu"),
+				  SUNXI_SRAM_MAP(0, 1, "ve")),
+};
+
+static const struct of_device_id sunxi_sram_dt_ids[] = {
+	{
+		.compatible	= "allwinner,sun4i-a10-sram-a3-a4",
+		.data		= &sun4i_a10_sram_a3_a4.data,
+	},
+	{
+		.compatible	= "allwinner,sun4i-a10-sram-c1",
+		.data		= &sun4i_a10_sram_c1.data,
+	},
+	{
+		.compatible	= "allwinner,sun4i-a10-sram-d",
+		.data		= &sun4i_a10_sram_d.data,
+	},
+	{
+		.compatible	= "allwinner,sun50i-a64-sram-c",
+		.data		= &sun50i_a64_sram_c.data,
+	},
+	{
+		.compatible	= "allwinner,sun50i-h616-ve-sram",
+		.data		= &sun50i_h616_ve_sram.data,
+	},
+	{}
+};
+
+static struct device *sram_dev;
+static DEFINE_SPINLOCK(sram_lock);
+static void __iomem *base;
+
+static int sunxi_sram_show(struct seq_file *s, void *data)
+{
+	struct device_node *sram_node, *section_node;
+	const struct sunxi_sram_data *sram_data;
+	const struct of_device_id *match;
+	const struct sunxi_sram_func *func;
+	const __be32 *sram_addr_p, *section_addr_p;
+	u32 val;
+
+	seq_puts(s, "Allwinner sunXi SRAM\n");
+	seq_puts(s, "--------------------\n\n");
+
+	for_each_child_of_node(sram_dev->of_node, sram_node) {
+		if (!of_device_is_compatible(sram_node, "mmio-sram"))
+			continue;
+
+		sram_addr_p = of_get_address(sram_node, 0, NULL, NULL);
+
+		seq_printf(s, "sram@%08x\n",
+			   be32_to_cpu(*sram_addr_p));
+
+		for_each_child_of_node(sram_node, section_node) {
+			match = of_match_node(sunxi_sram_dt_ids, section_node);
+			if (!match)
+				continue;
+			sram_data = match->data;
+
+			section_addr_p = of_get_address(section_node, 0,
+							NULL, NULL);
+
+			seq_printf(s, "\tsection@%04x\t(%s)\n",
+				   be32_to_cpu(*section_addr_p),
+				   sram_data->name);
+
+			val = readl(base + sram_data->reg);
+			val >>= sram_data->offset;
+			val &= GENMASK(sram_data->width - 1, 0);
+
+			for (func = sram_data->func; func->func; func++) {
+				seq_printf(s, "\t\t%s%c\n", func->func,
+					   func->reg_val == val ?
+					   '*' : ' ');
+			}
+		}
+
+		seq_puts(s, "\n");
+	}
+
+	return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(sunxi_sram);
+
+static inline struct sunxi_sram_desc *to_sram_desc(const struct sunxi_sram_data *data)
+{
+	return container_of(data, struct sunxi_sram_desc, data);
+}
+
+static const struct sunxi_sram_data *sunxi_sram_get_match(struct device_node *np, u8 val,
+							  unsigned int *reg_value)
+{
+	const struct of_device_id *match;
+	const struct sunxi_sram_data *data;
+	const struct sunxi_sram_func *func;
+
+	if (!of_device_is_available(np))
+		return ERR_PTR(-ENODEV);
+
+	match = of_match_node(sunxi_sram_dt_ids, np);
+	if (!match)
+		return ERR_PTR(-ENODEV);
+
+	data = match->data;
+	if (!data)
+		return ERR_PTR(-EINVAL);
+
+	for (func = data->func; func->func; func++)
+		if (val == func->val)
+			break;
+
+	if (!func->func)
+		return ERR_PTR(-EINVAL);
+
+	if (reg_value)
+		*reg_value = func->reg_val;
+
+	return data;
+}
+
+#define SUNXI_SRAM_PROP "allwinner,sram"
+#define SUNXI_SRAM_CELLS 1
+
+static int sunxi_sram_claim_one(struct device_node *np, u8 arg)
+{
+	const struct sunxi_sram_data *sram_data;
+	struct sunxi_sram_desc *sram_desc;
+	unsigned int device;
+	u32 val, mask;
+
+	sram_data = sunxi_sram_get_match(np, arg, &device);
+	if (IS_ERR(sram_data))
+		return PTR_ERR(sram_data);
+
+	sram_desc = to_sram_desc(sram_data);
+
+	spin_lock(&sram_lock);
+
+	if (sram_desc->claim_cnt) {
+		if (!WARN_ON(sram_desc->claim_cnt == U8_MAX))
+			sram_desc->claim_cnt++;
+	} else {
+		mask = GENMASK(sram_data->offset + sram_data->width - 1,
+			       sram_data->offset);
+		val = readl(base + sram_data->reg);
+		val &= ~mask;
+		writel(val | ((device << sram_data->offset) & mask),
+		       base + sram_data->reg);
+
+		sram_desc->claim_cnt++;
+	}
+
+	spin_unlock(&sram_lock);
+
+	return 0;
+}
+
+static void sunxi_sram_release_one(struct device_node *np, u8 arg)
+{
+	const struct sunxi_sram_data *sram_data;
+	struct sunxi_sram_desc *sram_desc;
+
+	sram_data = sunxi_sram_get_match(np, arg, NULL);
+	if (IS_ERR(sram_data))
+		return;
+
+	sram_desc = to_sram_desc(sram_data);
+
+	spin_lock(&sram_lock);
+	if (!WARN_ON(sram_desc->claim_cnt == 0))
+		sram_desc->claim_cnt--;
+	spin_unlock(&sram_lock);
+}
+
+int sunxi_sram_claim(struct device *dev)
+{
+	struct of_phandle_iterator it;
+	int err;
+	int count = 0;
+
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	if (!base)
+		return -EPROBE_DEFER;
+
+	if (!dev || !dev->of_node)
+		return -EINVAL;
+
+	of_for_each_phandle(&it, err, dev->of_node, SUNXI_SRAM_PROP,
+			    NULL, SUNXI_SRAM_CELLS) {
+		u32 args[SUNXI_SRAM_CELLS];
+
+		of_phandle_iterator_args(&it, args, SUNXI_SRAM_CELLS);
+
+		err = sunxi_sram_claim_one(it.node, args[0]);
+		if (err)
+			goto err;
+
+		count++;
+	}
+
+	if (count == 0)
+		return -ENOENT;
+
+	return 0;
+
+err:
+	while (count--) {
+		struct of_phandle_args args;
+
+		of_parse_phandle_with_fixed_args(dev->of_node, SUNXI_SRAM_PROP,
+						 SUNXI_SRAM_CELLS, count, &args);
+		sunxi_sram_release_one(args.np, args.args[0]);
+	}
+
+	return err;
+}
+EXPORT_SYMBOL(sunxi_sram_claim);
+
+void sunxi_sram_release(struct device *dev)
+{
+	struct of_phandle_iterator it;
+	int err;
+
+	if (!dev || !dev->of_node)
+		return;
+
+	of_for_each_phandle(&it, err, dev->of_node, SUNXI_SRAM_PROP,
+			    NULL, SUNXI_SRAM_CELLS) {
+		u32 args[SUNXI_SRAM_CELLS];
+
+		of_phandle_iterator_args(&it, args, SUNXI_SRAM_CELLS);
+
+		sunxi_sram_release_one(it.node, args[0]);
+	}
+}
+EXPORT_SYMBOL(sunxi_sram_release);
+
+struct sunxi_sramc_variant {
+	int num_emac_clocks;
+	bool has_ldo_ctrl;
+	bool has_ths_offset;
+};
+
+static const struct sunxi_sramc_variant sun4i_a10_sramc_variant = {
+	/* Nothing special */
+};
+
+static const struct sunxi_sramc_variant sun8i_h3_sramc_variant = {
+	.num_emac_clocks = 1,
+};
+
+static const struct sunxi_sramc_variant sun20i_d1_sramc_variant = {
+	.num_emac_clocks = 1,
+	.has_ldo_ctrl = true,
+};
+
+static const struct sunxi_sramc_variant sun50i_a64_sramc_variant = {
+	.num_emac_clocks = 1,
+};
+
+static const struct sunxi_sramc_variant sun50i_h616_sramc_variant = {
+	.num_emac_clocks = 2,
+	.has_ths_offset = true,
+};
+
+static const struct sunxi_sramc_variant sun55i_a523_sramc_variant = {
+	.num_emac_clocks = 2,
+};
+
+#define SUNXI_SRAM_THS_OFFSET_REG	0x0
+#define SUNXI_SRAM_EMAC_CLOCK_REG	0x30
+#define SUNXI_SYS_LDO_CTRL_REG		0x150
+
+static bool sunxi_sram_regmap_accessible_reg(struct device *dev,
+					     unsigned int reg)
+{
+	const struct sunxi_sramc_variant *variant = dev_get_drvdata(dev);
+
+	if (reg == SUNXI_SRAM_THS_OFFSET_REG && variant->has_ths_offset)
+		return true;
+	if (reg >= SUNXI_SRAM_EMAC_CLOCK_REG &&
+	    reg <  SUNXI_SRAM_EMAC_CLOCK_REG + variant->num_emac_clocks * 4)
+		return true;
+	if (reg == SUNXI_SYS_LDO_CTRL_REG && variant->has_ldo_ctrl)
+		return true;
+
+	return false;
+}
+
+static void sunxi_sram_lock(void *_lock)
+{
+	spinlock_t *lock = _lock;
+
+	spin_lock(lock);
+}
+
+static void sunxi_sram_unlock(void *_lock)
+{
+	spinlock_t *lock = _lock;
+
+	spin_unlock(lock);
+}
+
+static const struct regmap_config sunxi_sram_regmap_config = {
+	.reg_bits       = 32,
+	.val_bits       = 32,
+	.reg_stride     = 4,
+	/* last defined register */
+	.max_register   = SUNXI_SYS_LDO_CTRL_REG,
+	/* other devices have no business accessing other registers */
+	.readable_reg	= sunxi_sram_regmap_accessible_reg,
+	.writeable_reg	= sunxi_sram_regmap_accessible_reg,
+	.lock		= sunxi_sram_lock,
+	.unlock		= sunxi_sram_unlock,
+	.lock_arg	= &sram_lock,
+};
+
+static int __init sunxi_sram_probe(struct platform_device *pdev)
+{
+	const struct sunxi_sramc_variant *variant;
+	struct device *dev = &pdev->dev;
+	struct regmap *regmap;
+	int ret;
+
+	sram_dev = &pdev->dev;
+
+	variant = of_device_get_match_data(&pdev->dev);
+	if (!variant)
+		return -EINVAL;
+
+	dev_set_drvdata(dev, (struct sunxi_sramc_variant *)variant);
+
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	if (variant->num_emac_clocks || variant->has_ldo_ctrl) {
+		regmap = devm_regmap_init_mmio(dev, base, &sunxi_sram_regmap_config);
+		if (IS_ERR(regmap))
+			return PTR_ERR(regmap);
+
+		ret = of_syscon_register_regmap(dev->of_node, regmap);
+		if (ret)
+			return ret;
+	}
+
+	of_platform_populate(dev->of_node, NULL, NULL, dev);
+
+	debugfs_create_file("sram", 0444, NULL, NULL, &sunxi_sram_fops);
+
+	return 0;
+}
+
+static const struct of_device_id sunxi_sram_dt_match[] = {
+	{
+		.compatible = "allwinner,sun4i-a10-sram-controller",
+		.data = &sun4i_a10_sramc_variant,
+	},
+	{
+		.compatible = "allwinner,sun4i-a10-system-control",
+		.data = &sun4i_a10_sramc_variant,
+	},
+	{
+		.compatible = "allwinner,sun5i-a13-system-control",
+		.data = &sun4i_a10_sramc_variant,
+	},
+	{
+		.compatible = "allwinner,sun8i-a23-system-control",
+		.data = &sun4i_a10_sramc_variant,
+	},
+	{
+		.compatible = "allwinner,sun8i-h3-system-control",
+		.data = &sun8i_h3_sramc_variant,
+	},
+	{
+		.compatible = "allwinner,sun20i-d1-system-control",
+		.data = &sun20i_d1_sramc_variant,
+	},
+	{
+		.compatible = "allwinner,sun50i-a64-sram-controller",
+		.data = &sun50i_a64_sramc_variant,
+	},
+	{
+		.compatible = "allwinner,sun50i-a64-system-control",
+		.data = &sun50i_a64_sramc_variant,
+	},
+	{
+		.compatible = "allwinner,sun50i-h5-system-control",
+		.data = &sun50i_a64_sramc_variant,
+	},
+	{
+		.compatible = "allwinner,sun50i-h616-system-control",
+		.data = &sun50i_h616_sramc_variant,
+	},
+	{
+		.compatible = "allwinner,sun55i-a523-system-control",
+		.data = &sun55i_a523_sramc_variant,
+	},
+	{ },
+};
+MODULE_DEVICE_TABLE(of, sunxi_sram_dt_match);
+
+static struct platform_driver sunxi_sram_driver = {
+	.driver = {
+		.name		= "sunxi-sram",
+		.of_match_table	= sunxi_sram_dt_match,
+	},
+};
+builtin_platform_driver_probe(sunxi_sram_driver, sunxi_sram_probe);
+
+MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
+MODULE_DESCRIPTION("Allwinner sunXi SRAM Controller Driver");