[RFC 5/7] bus: domainsctrl: Add driver for STM32 ETZPC controller

[Benjamin Gaignard]

STM32 Extended TrustZone Protection Controller (ETZPC) got 3 domains:
- secure: hardware blocks are only accessible by software running on trust
  zone.
- non-secure: hardware blocks are accessible by non-secure software (i.e.
    linux kernel).
- coprocessor: hardware blocks are only accessible by the corpocessor.

Each hardware block status is defined by a 2 bits field and all of
them are packed into 32 bits registers. ETZPC can manage up to 94
hardware blocks.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxx>
---
 drivers/bus/domains/Kconfig                   |   7 ++
 drivers/bus/domains/Makefile                  |   1 +
 drivers/bus/domains/stm32-etzpc.c             | 140 ++++++++++++++++++++++++++
 include/dt-bindings/bus/domains/stm32-etzpc.h |  25 +++++
 4 files changed, 173 insertions(+)
 create mode 100644 drivers/bus/domains/stm32-etzpc.c
 create mode 100644 include/dt-bindings/bus/domains/stm32-etzpc.h

diff --git a/drivers/bus/domains/Kconfig b/drivers/bus/domains/Kconfig
index 5ba15f750bee..7afd209e8c4f 100644
--- a/drivers/bus/domains/Kconfig
+++ b/drivers/bus/domains/Kconfig
@@ -4,4 +4,11 @@ config DOMAINS_CONTROLLERS
 	bool "Support of bus domains controllers"
 	depends on OF
 
+config STM32_ETZPC
+	bool "STM32 ETZPC Domain Controller"
+	depends on DOMAINS_CONTROLLERS && MACH_STM32MP157
+	help
+	  Select y to enable STM32 Extended TrustZone Protection
+	  Controller (ETZPC)
+
 endmenu
diff --git a/drivers/bus/domains/Makefile b/drivers/bus/domains/Makefile
index 262338b7cad5..8000de6023a5 100644
--- a/drivers/bus/domains/Makefile
+++ b/drivers/bus/domains/Makefile
@@ -1 +1,2 @@
 obj-$(CONFIG_DOMAINS_CONTROLLERS) += domainsctrl.o
+obj-$(CONFIG_STM32_ETZPC) += stm32-etzpc.o
diff --git a/drivers/bus/domains/stm32-etzpc.c b/drivers/bus/domains/stm32-etzpc.c
new file mode 100644
index 000000000000..8a03128a8715
--- /dev/null
+++ b/drivers/bus/domains/stm32-etzpc.c
@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) STMicroelectronics 2018 - All Rights Reserved
+ * Author: Benjamin Gaignard <benjamin.gaignard@xxxxxx> for STMicroelectronics.
+ */
+
+#include <linux/device.h>
+#include <linux/domainsctrl.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#include <dt-bindings/bus/domains/stm32-etzpc.h>
+
+#define ETZPC_DECPROT	0x010
+#define ETZPC_NUM_LOCKS	94
+
+struct stm32_etzpc {
+	struct regmap_field *fields[ETZPC_NUM_LOCKS];
+};
+
+static int stm32_etzpc_set_config(struct device *dev,
+				  struct of_phandle_args *out_args)
+{
+	struct stm32_etzpc *etzpc = dev_get_drvdata(dev);
+	int index = out_args->args[0];
+	unsigned int value = out_args->args[1];
+	u32 status;
+
+	if (out_args->args_count != 2)
+		return -EINVAL;
+
+	if (index >= ETZPC_NUM_LOCKS)
+		return -EINVAL;
+
+	if (value > STM32_ETZPC_NON_SECURE)
+		return -EINVAL;
+
+	regmap_field_force_write(etzpc->fields[index], value);
+
+	/* Hardware could denied the new value, read it back to check it */
+	regmap_field_read(etzpc->fields[index], &status);
+
+	if (value != status) {
+		dev_info(dev, "failed to set configuration: index %d, value %d\n",
+			 index, value);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static struct domains_ctrl_ops stm32_etzpc_ops = {
+	.set_config = stm32_etzpc_set_config,
+};
+
+static const struct regmap_config stm32_etzpc_regmap_cfg = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = sizeof(u32),
+	.max_register = 0x3FF,
+	.fast_io = true,
+};
+
+static int stm32_etzpc_probe(struct platform_device *pdev)
+{
+	struct stm32_etzpc *etzpc;
+	struct resource *res;
+	void __iomem *mmio;
+	struct regmap *regmap;
+	int i;
+
+	etzpc = devm_kzalloc(&pdev->dev, sizeof(*etzpc), GFP_KERNEL);
+	if (!etzpc)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	mmio = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(mmio))
+		return PTR_ERR(mmio);
+
+	regmap = devm_regmap_init_mmio(&pdev->dev, mmio,
+				       &stm32_etzpc_regmap_cfg);
+
+	for (i = 0; i < ETZPC_NUM_LOCKS; i++) {
+		struct reg_field field;
+
+		/*
+		 * Each hardware block status is defined by
+		 * a 2 bits field and all of them are packed into
+		 * 32 bits registers. Do some computation to get
+		 * register offset and the shift.
+		 */
+		field.reg = ETZPC_DECPROT + (i >> 4) * sizeof(u32);
+		field.lsb = (i % 0x10) << 1;
+		field.msb = field.lsb + 1;
+
+		etzpc->fields[i] = devm_regmap_field_alloc(&pdev->dev,
+							   regmap, field);
+	}
+
+	platform_set_drvdata(pdev, etzpc);
+
+	return domainsctrl_register(&pdev->dev, &stm32_etzpc_ops);
+}
+
+static int stm32_etzpc_remove(struct platform_device *pdev)
+{
+	domainsctrl_unregister(&pdev->dev);
+
+	return 0;
+}
+
+static const struct of_device_id stm32_etzpc_of_match[] = {
+	{ .compatible = "st,stm32-etzpc" },
+	{ /* end node */ }
+};
+MODULE_DEVICE_TABLE(of, stm32_etzpc_of_match);
+
+static struct platform_driver stm32_etzpc_driver = {
+	.probe  = stm32_etzpc_probe,
+	.remove = stm32_etzpc_remove,
+	.driver = {
+		.name = "stm32-etzpc",
+		.of_match_table = stm32_etzpc_of_match,
+	},
+};
+
+static int __init stm32_etzpc_init(void)
+{
+	return platform_driver_register(&stm32_etzpc_driver);
+}
+arch_initcall(stm32_etzpc_init);
+
+MODULE_AUTHOR("Benjamin Gaignard <benjamin.gaignard@xxxxxx>");
+MODULE_DESCRIPTION("STMicroelectronics STM32 Bus Dommains Controller");
diff --git a/include/dt-bindings/bus/domains/stm32-etzpc.h b/include/dt-bindings/bus/domains/stm32-etzpc.h
new file mode 100644
index 000000000000..93190fa29a9c
--- /dev/null
+++ b/include/dt-bindings/bus/domains/stm32-etzpc.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) STMicroelectronics 2018 - All Rights Reserved
+ * Author: Benjamin Gaignard <benjamin.gaignard@xxxxxx> for STMicroelectronics.
+ */
+
+#ifndef _STM32_ETZPC_H_
+#define _STM32_ETZPC_H_
+
+/* ETZPC domains: secure, non-secure or coprocessor*/
+#define STM32_ETZPC_SECURE	1
+#define STM32_ETPCZ_COPRO	2
+#define STM32_ETZPC_NON_SECURE	3
+
+/* ETZPC hard blaokcs index */
+#define STM32_ETZPC_USART1	3
+#define STM32_ETZPC_SPI6	4
+#define STM32_ETZPC_I2C4	5
+#define STM32_ETZPC_RNG1	7
+#define STM32_ETZPC_HASH1	8
+#define STM32_ETZPC_CRYP1	9
+#define STM32_ETZPC_I2C6	12
+#define STM32_ETZPC_CEC		38
+
+#endif /* _STM32_ETZPC_H_ */
-- 
2.15.0