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.gaign...@st.com>
---
 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.gaign...@st.com> 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.gaign...@st.com>");
+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.gaign...@st.com> 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

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