[PATCH v4 2/2] remoteproc: add AMD BRAM-based remote processor driver

[Ben Levinsky <ben.levinsky@amd.com>]

Add a remoteproc driver for AMD soft-core processor subsystems
instantiated in programmable logic and using dual-port BRAM for
firmware storage and execution.

The driver parses the firmware memory window from the remoteproc device
node's reg property, interprets that address and size in the
processor-local address space, and then uses standard devicetree
address translation through the parent bus ranges property to obtain
the corresponding Linux-visible system physical address.

The resulting translated region is registered as the executable
remoteproc carveout and coredump segment.

The processor is controlled through an active-low reset GPIO and a
subsystem clock. The clock is enabled before reset is released, and the
processor is kept in reset until firmware loading completes.

The firmware-name property is optional, allowing firmware to be
assigned later through the remoteproc framework. Firmware images
without a resource table are also accepted.

Signed-off-by: Ben Levinsky <ben.levinsky@amd.com>
---
 drivers/remoteproc/Kconfig          |  11 ++
 drivers/remoteproc/Makefile         |   1 +
 drivers/remoteproc/amd_bram_rproc.c | 213 ++++++++++++++++++++++++++++
 3 files changed, 225 insertions(+)
 create mode 100644 drivers/remoteproc/amd_bram_rproc.c

diff --git a/drivers/remoteproc/Kconfig b/drivers/remoteproc/Kconfig
index c521c744e7db..58fa566b609f 100644
--- a/drivers/remoteproc/Kconfig
+++ b/drivers/remoteproc/Kconfig
@@ -23,6 +23,17 @@ config REMOTEPROC_CDEV
 
 	  It's safe to say N if you don't want to use this interface.
 
+config AMD_BRAM_REMOTEPROC
+	tristate "AMD BRAM-based remoteproc support"
+	depends on OF && COMMON_CLK && (GPIOLIB || COMPILE_TEST)
+	help
+	  Say y or m here to support a BRAM-based remote processor managed
+	  through the remoteproc framework.
+
+	  The processor is controlled through a reset GPIO and clock.
+
+	  If unsure, say N.
+
 config IMX_REMOTEPROC
 	tristate "i.MX remoteproc support"
 	depends on ARCH_MXC
diff --git a/drivers/remoteproc/Makefile b/drivers/remoteproc/Makefile
index 1c7598b8475d..5c39664b50c3 100644
--- a/drivers/remoteproc/Makefile
+++ b/drivers/remoteproc/Makefile
@@ -11,6 +11,7 @@ remoteproc-y				+= remoteproc_sysfs.o
 remoteproc-y				+= remoteproc_virtio.o
 remoteproc-y				+= remoteproc_elf_loader.o
 obj-$(CONFIG_REMOTEPROC_CDEV)		+= remoteproc_cdev.o
+obj-$(CONFIG_AMD_BRAM_REMOTEPROC)	+= amd_bram_rproc.o
 obj-$(CONFIG_IMX_REMOTEPROC)		+= imx_rproc.o
 obj-$(CONFIG_IMX_DSP_REMOTEPROC)	+= imx_dsp_rproc.o
 obj-$(CONFIG_INGENIC_VPU_RPROC)		+= ingenic_rproc.o
diff --git a/drivers/remoteproc/amd_bram_rproc.c b/drivers/remoteproc/amd_bram_rproc.c
new file mode 100644
index 000000000000..a595875f9ce8
--- /dev/null
+++ b/drivers/remoteproc/amd_bram_rproc.c
@@ -0,0 +1,213 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * AMD BRAM-based Remote Processor driver
+ *
+ * Copyright (C) 2026 Advanced Micro Devices, Inc.
+ *
+ * This driver supports soft-core processors (MicroBlaze, MicroBlaze-V, or
+ * similar) instantiated in AMD programmable logic, using dual-port BRAM
+ * for firmware storage and execution.
+ *
+ * The firmware memory (BRAM) is described in the processor-local address
+ * space and translated to the Linux-visible system physical address with
+ * standard devicetree address translation.
+ *
+ * Reset is controlled via GPIO connected to Processor System Reset IP.
+ */
+
+#include <linux/clk.h>
+#include <linux/dma-mapping.h>
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/remoteproc.h>
+
+#include "remoteproc_internal.h"
+
+/**
+ * struct amd_bram_rproc - AMD BRAM-based remoteproc private data
+ * @dev: device pointer
+ * @reset: GPIO descriptor for reset control (active-low)
+ * @clk: processor clock
+ */
+struct amd_bram_rproc {
+	struct device *dev;
+	struct gpio_desc *reset;
+	struct clk *clk;
+};
+
+static int amd_bram_rproc_prepare(struct rproc *rproc)
+{
+	struct amd_bram_rproc *priv = rproc->priv;
+	struct rproc_mem_entry *mem;
+	struct resource res;
+	u64 da, size;
+	int ret;
+
+	ret = of_property_read_reg(priv->dev->of_node, 0, &da, &size);
+	if (ret) {
+		dev_err(priv->dev, "failed to parse executable memory reg\n");
+		return ret;
+	}
+
+	if (!size || size > U32_MAX) {
+		dev_err(priv->dev, "invalid executable memory size\n");
+		return -EINVAL;
+	}
+
+	if (da > U32_MAX) {
+		dev_err(priv->dev, "invalid executable memory address\n");
+		return -EINVAL;
+	}
+
+	ret = of_address_to_resource(priv->dev->of_node, 0, &res);
+	if (ret) {
+		dev_err(priv->dev, "failed to translate executable memory reg\n");
+		return ret;
+	}
+
+	mem = rproc_mem_entry_init(priv->dev, NULL, (dma_addr_t)res.start,
+				   resource_size(&res), da,
+				   rproc_mem_entry_ioremap_wc,
+				   rproc_mem_entry_iounmap,
+				   dev_name(priv->dev));
+	if (!mem)
+		return -ENOMEM;
+
+	rproc_add_carveout(rproc, mem);
+	rproc_coredump_add_segment(rproc, da, resource_size(&res));
+
+	return 0;
+}
+
+static int amd_bram_rproc_start(struct rproc *rproc)
+{
+	struct amd_bram_rproc *priv = rproc->priv;
+	int ret;
+
+	/* Enable clock before releasing reset */
+	ret = clk_prepare_enable(priv->clk);
+	if (ret) {
+		dev_err(priv->dev, "failed to enable clock: %d\n", ret);
+		return ret;
+	}
+
+	/* Deassert reset and let the processor run. */
+	ret = gpiod_set_value_cansleep(priv->reset, 0);
+	if (ret) {
+		dev_err(priv->dev, "failed to deassert reset: %d\n", ret);
+		clk_disable_unprepare(priv->clk);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int amd_bram_rproc_stop(struct rproc *rproc)
+{
+	struct amd_bram_rproc *priv = rproc->priv;
+	int ret;
+
+	/* Assert reset before disabling the processor clock. */
+	ret = gpiod_set_value_cansleep(priv->reset, 1);
+	if (ret) {
+		dev_err(priv->dev, "failed to assert reset: %d\n", ret);
+		return ret;
+	}
+
+	/* Disable clock after asserting reset */
+	clk_disable_unprepare(priv->clk);
+
+	return 0;
+}
+
+static int amd_bram_rproc_parse_fw(struct rproc *rproc,
+				   const struct firmware *fw)
+{
+	rproc_elf_load_rsc_table_optional(rproc, fw, dev_dbg,
+					  "no resource table found\n");
+	return 0;
+}
+
+static const struct rproc_ops amd_bram_rproc_ops = {
+	.prepare	= amd_bram_rproc_prepare,
+	.start		= amd_bram_rproc_start,
+	.stop		= amd_bram_rproc_stop,
+	.load		= rproc_elf_load_segments,
+	.sanity_check	= rproc_elf_sanity_check,
+	.get_boot_addr	= rproc_elf_get_boot_addr,
+	.parse_fw	= amd_bram_rproc_parse_fw,
+};
+
+static int amd_bram_rproc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct amd_bram_rproc *priv;
+	const char *fw_name = NULL;
+	struct rproc *rproc;
+	int ret;
+
+	ret = rproc_of_parse_firmware(dev, 0, &fw_name);
+	if (ret < 0 && ret != -EINVAL)
+		return dev_err_probe(dev, ret,
+				     "failed to parse firmware-name property\n");
+
+	rproc = devm_rproc_alloc(dev, dev_name(dev), &amd_bram_rproc_ops,
+				 fw_name, sizeof(*priv));
+	if (!rproc)
+		return -ENOMEM;
+
+	priv = rproc->priv;
+	priv->dev = dev;
+
+	/* Get the processor clock */
+	priv->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(priv->clk))
+		return dev_err_probe(dev, PTR_ERR(priv->clk),
+				     "failed to get clock\n");
+
+	/*
+	 * Keep the processor in reset until remoteproc has finished loading
+	 * firmware into the executable memory window described by reg and
+	 * translated through the parent bus ranges property.
+	 */
+	priv->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(priv->reset))
+		return dev_err_probe(dev, PTR_ERR(priv->reset),
+				     "failed to get reset gpio\n");
+
+	rproc->auto_boot = false;
+
+	ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(64));
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to set DMA mask\n");
+
+	platform_set_drvdata(pdev, rproc);
+
+	ret = devm_rproc_add(dev, rproc);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to register rproc\n");
+
+	return 0;
+}
+
+static const struct of_device_id amd_bram_rproc_of_match[] = {
+	{ .compatible = "xlnx,zynqmp-bram-rproc" },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, amd_bram_rproc_of_match);
+
+static struct platform_driver amd_bram_rproc_driver = {
+	.probe = amd_bram_rproc_probe,
+	.driver = {
+		.name = "amd-bram-rproc",
+		.of_match_table = amd_bram_rproc_of_match,
+	},
+};
+module_platform_driver(amd_bram_rproc_driver);
+
+MODULE_DESCRIPTION("AMD BRAM-based Remote Processor driver");
+MODULE_AUTHOR("Ben Levinsky <ben.levinsky@amd.com>");
+MODULE_LICENSE("GPL");
-- 
2.34.1