[PATCH 4/5] remoteproc: meson-mx-ao-arc: Add a driver for the AO ARC remote procesor

[Martin Blumenstingl]

Amlogic Meson6, Meson8, Meson8b and Meson8m2 embed an ARC core in the
Always-On (AO) power-domain. This is typically used for waking up the
ARM cores after system suspend.

The configuration is spread across three different registers:
- AO_REMAP_REG0 which must be programmed to zero, it's actual purpose
  is unknown. There is a second remap register which is not used in the
  vendor kernel (which served as reference for this driver).
- AO_CPU_CNTL is used to start and stop the ARC core.
- AO_SECURE_REG0 in the SECBUS2 register area with unknown purpose.

To boot the ARC core we also need to enable it's gate clock and trigger
a reset.

The actual code for this ARC core can come from an ELF binary, for
example by building the Zephyr RTOS for an ARC EM4 core and then taking
"zephyr.elf" as firmware. This executable does not have any "rsc table"
so we are skipping rproc_elf_load_rsc_table (rproc_ops.parse_fw) and
rproc_elf_find_loaded_rsc_table (rproc_ops.find_loaded_rsc_table).

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx>
---
 drivers/remoteproc/Kconfig           |  11 ++
 drivers/remoteproc/Makefile          |   1 +
 drivers/remoteproc/meson_mx_ao_arc.c | 240 +++++++++++++++++++++++++++
 3 files changed, 252 insertions(+)
 create mode 100644 drivers/remoteproc/meson_mx_ao_arc.c

diff --git a/drivers/remoteproc/Kconfig b/drivers/remoteproc/Kconfig
index 9e7efe542f69..0e7fb91635fe 100644
--- a/drivers/remoteproc/Kconfig
+++ b/drivers/remoteproc/Kconfig
@@ -125,6 +125,17 @@ config KEYSTONE_REMOTEPROC
 	  It's safe to say N here if you're not interested in the Keystone
 	  DSPs or just want to use a bare minimum kernel.
 
+config MESON_MX_AO_ARC_REMOTEPROC
+	tristate "Amlogic Meson6/8/8b/8m2 AO ARC remote processor support"
+	depends on HAS_IOMEM
+	depends on (ARM && ARCH_MESON) || COMPILE_TEST
+	select GENERIC_ALLOCATOR
+	help
+	  Say m or y here to have support for the AO ARC remote processor
+	  on Amlogic Meson6/Meson8/Meson8b/Meson8m2 SoCs. This is
+	  typically used for system suspend.
+	  If unusre say N.
+
 config PRU_REMOTEPROC
 	tristate "TI PRU remoteproc support"
 	depends on TI_PRUSS
diff --git a/drivers/remoteproc/Makefile b/drivers/remoteproc/Makefile
index bb26c9e4ef9c..ce1abeb30907 100644
--- a/drivers/remoteproc/Makefile
+++ b/drivers/remoteproc/Makefile
@@ -18,6 +18,7 @@ obj-$(CONFIG_OMAP_REMOTEPROC)		+= omap_remoteproc.o
 obj-$(CONFIG_WKUP_M3_RPROC)		+= wkup_m3_rproc.o
 obj-$(CONFIG_DA8XX_REMOTEPROC)		+= da8xx_remoteproc.o
 obj-$(CONFIG_KEYSTONE_REMOTEPROC)	+= keystone_remoteproc.o
+obj-$(CONFIG_MESON_MX_AO_ARC_REMOTEPROC)+= meson_mx_ao_arc.o
 obj-$(CONFIG_PRU_REMOTEPROC)		+= pru_rproc.o
 obj-$(CONFIG_QCOM_PIL_INFO)		+= qcom_pil_info.o
 obj-$(CONFIG_QCOM_RPROC_COMMON)		+= qcom_common.o
diff --git a/drivers/remoteproc/meson_mx_ao_arc.c b/drivers/remoteproc/meson_mx_ao_arc.c
new file mode 100644
index 000000000000..1deb03ca30f4
--- /dev/null
+++ b/drivers/remoteproc/meson_mx_ao_arc.c
@@ -0,0 +1,240 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2020 Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/property.h>
+#include <linux/genalloc.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/remoteproc.h>
+#include <linux/reset.h>
+#include <linux/sizes.h>
+
+#include "remoteproc_internal.h"
+
+#define AO_REMAP_REG0					0x0
+#define AO_REMAP_REG1					0x4
+
+#define AO_CPU_CNTL					0x0
+	#define AO_CPU_CNTL_MEM_ADDR_UPPER		GENMASK(28, 16)
+	#define AO_CPU_CNTL_HALT			BIT(9)
+	#define AO_CPU_CNTL_UNKNONWN			BIT(8)
+	#define AO_CPU_CNTL_RUN				BIT(0)
+
+#define AO_CPU_STAT					0x4
+
+#define AO_SECURE_REG0					0x0
+	#define AO_SECURE_REG0_UNKNOWN			GENMASK(23, 8)
+
+#define MESON_AO_RPROC_SRAM_USABLE_BITS			GENMASK(31, 20)
+#define MESON_AO_RPROC_MEMORY_OFFSET			0x10000000
+
+struct meson_mx_ao_arc_rproc_priv {
+	void __iomem		*remap_base;
+	void __iomem		*cpu_base;
+	unsigned long		sram_va;
+	phys_addr_t		sram_pa;
+	size_t			sram_size;
+	struct gen_pool		*sram_pool;
+	struct reset_control	*arc_reset;
+	struct clk		*arc_pclk;
+	struct regmap		*secbus2_regmap;
+};
+
+static int meson_mx_ao_arc_rproc_start(struct rproc *rproc)
+{
+	struct meson_mx_ao_arc_rproc_priv *priv = rproc->priv;
+	phys_addr_t phys_addr;
+	int ret;
+
+	ret = clk_prepare_enable(priv->arc_pclk);
+	if (ret)
+		return ret;
+
+	writel(0, priv->remap_base + AO_REMAP_REG0);
+	usleep_range(10, 100);
+
+	regmap_update_bits(priv->secbus2_regmap, AO_SECURE_REG0,
+			   AO_SECURE_REG0_UNKNOWN, 0);
+
+	ret = reset_control_reset(priv->arc_reset);
+	if (ret) {
+		clk_disable_unprepare(priv->arc_pclk);
+		return ret;
+	}
+
+	usleep_range(10, 100);
+
+	/* convert from 0xd9000000 to 0xc9000000 as the vendor driver does */
+	phys_addr = priv->sram_pa - MESON_AO_RPROC_MEMORY_OFFSET;
+
+	writel(FIELD_PREP(AO_CPU_CNTL_MEM_ADDR_UPPER,
+			  FIELD_GET(MESON_AO_RPROC_SRAM_USABLE_BITS, phys_addr)) |
+	       AO_CPU_CNTL_UNKNONWN | AO_CPU_CNTL_RUN,
+	       priv->cpu_base + AO_CPU_CNTL);
+	usleep_range(20, 200);
+
+	return 0;
+}
+
+static int meson_mx_ao_arc_rproc_stop(struct rproc *rproc)
+{
+	struct meson_mx_ao_arc_rproc_priv *priv = rproc->priv;
+
+	writel(AO_CPU_CNTL_HALT, priv->cpu_base + AO_CPU_CNTL);
+
+	clk_disable_unprepare(priv->arc_pclk);
+
+	return 0;
+}
+
+static void *meson_mx_ao_arc_rproc_da_to_va(struct rproc *rproc, u64 da,
+					    size_t len)
+{
+	struct meson_mx_ao_arc_rproc_priv *priv = rproc->priv;
+
+	if ((da + len) >= priv->sram_size)
+		return NULL;
+
+	return (void *)priv->sram_va + da;
+}
+
+static struct rproc_ops meson_mx_ao_arc_rproc_ops = {
+	.start		= meson_mx_ao_arc_rproc_start,
+	.stop		= meson_mx_ao_arc_rproc_stop,
+	.da_to_va	= meson_mx_ao_arc_rproc_da_to_va,
+	.get_boot_addr	= rproc_elf_get_boot_addr,
+	.load		= rproc_elf_load_segments,
+	.sanity_check	= rproc_elf_sanity_check,
+};
+
+static int meson_mx_ao_arc_rproc_probe(struct platform_device *pdev)
+{
+	struct meson_mx_ao_arc_rproc_priv *priv;
+	struct platform_device *secbus2_pdev;
+	struct device *dev = &pdev->dev;
+	const char *fw_name;
+	struct rproc *rproc;
+	int ret;
+
+	ret = device_property_read_string(dev, "firmware-name", &fw_name);
+	if (ret)
+		fw_name = NULL;
+
+	rproc = devm_rproc_alloc(dev, "meson-mx-ao-arc",
+				 &meson_mx_ao_arc_rproc_ops, fw_name,
+				 sizeof(*priv));
+	if (!rproc)
+		return -ENOMEM;
+
+	rproc->has_iommu = false;
+	priv = rproc->priv;
+
+	priv->sram_pool = of_gen_pool_get(dev->of_node, "sram", 0);
+	if (!priv->sram_pool) {
+		dev_err(dev, "Could not get SRAM pool\n");
+		return -ENODEV;
+	}
+
+	priv->sram_size = gen_pool_avail(priv->sram_pool);
+
+	priv->sram_va = gen_pool_alloc(priv->sram_pool, priv->sram_size);
+	if (!priv->sram_va) {
+		dev_err(dev, "Could not alloc memory in SRAM pool\n");
+		return -ENOMEM;
+	}
+
+	priv->sram_pa = gen_pool_virt_to_phys(priv->sram_pool, priv->sram_va);
+	if (priv->sram_pa & ~MESON_AO_RPROC_SRAM_USABLE_BITS) {
+		dev_err(dev, "SRAM address contains unusable bits\n");
+		ret = -EINVAL;
+		goto err_free_genpool;
+	}
+
+	priv->secbus2_regmap = syscon_regmap_lookup_by_phandle(dev->of_node,
+							       "amlogic,secbus2");
+	if (IS_ERR(priv->secbus2_regmap)) {
+		dev_err(dev, "Failed to find SECBUS2 regmap\n");
+		ret = PTR_ERR(priv->secbus2_regmap);
+		goto err_free_genpool;
+	}
+
+	priv->remap_base = devm_platform_ioremap_resource_byname(pdev, "remap");
+	if (IS_ERR(priv->remap_base)) {
+		ret = PTR_ERR(priv->remap_base);
+		goto err_free_genpool;
+	}
+
+	priv->cpu_base = devm_platform_ioremap_resource_byname(pdev, "cpu");
+	if (IS_ERR(priv->cpu_base)) {
+		ret = PTR_ERR(priv->cpu_base);
+		goto err_free_genpool;
+	}
+
+	priv->arc_reset = devm_reset_control_get_exclusive(dev, NULL);
+	if (IS_ERR(priv->arc_reset)) {
+		dev_err(dev, "Failed to get ARC reset\n");
+		ret = PTR_ERR(priv->arc_reset);
+		goto err_free_genpool;
+	}
+
+	priv->arc_pclk = devm_clk_get(dev, NULL);
+	if (IS_ERR(priv->arc_pclk)) {
+		dev_err(dev, "Failed to get the ARC PCLK\n");
+		ret = PTR_ERR(priv->arc_pclk);
+		goto err_free_genpool;
+	}
+
+	platform_set_drvdata(pdev, rproc);
+
+	ret = rproc_add(rproc);
+	if (ret)
+		goto err_free_genpool;
+
+	return 0;
+
+err_free_genpool:
+	gen_pool_free(priv->sram_pool, priv->sram_va, priv->sram_size);
+	return ret;
+}
+
+static int meson_mx_ao_arc_rproc_remove(struct platform_device *pdev)
+{
+	struct rproc *rproc = platform_get_drvdata(pdev);
+	struct meson_mx_ao_arc_rproc_priv *priv = rproc->priv;
+
+	rproc_del(rproc);
+	gen_pool_free(priv->sram_pool, priv->sram_va, priv->sram_size);
+
+	return 0;
+}
+
+static const struct of_device_id meson_mx_ao_arc_rproc_match[] = {
+	{ .compatible = "amlogic,meson8-ao-arc" },
+	{ .compatible = "amlogic,meson8b-ao-arc" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, meson_mx_ao_arc_rproc_match);
+
+static struct platform_driver meson_mx_ao_arc_rproc_driver = {
+	.probe = meson_mx_ao_arc_rproc_probe,
+	.remove = meson_mx_ao_arc_rproc_remove,
+	.driver = {
+		.name = "meson-mx-ao-arc-rproc",
+		.of_match_table = of_match_ptr(meson_mx_ao_arc_rproc_match),
+	},
+};
+module_platform_driver(meson_mx_ao_arc_rproc_driver);
+
+MODULE_DESCRIPTION("Amlogic Meson6/8/8b/8m2 AO ARC remote processor driver");
+MODULE_AUTHOR("Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx>");
+MODULE_LICENSE("GPL v2");
-- 
2.30.0