[PATCH v8 09/13] bus: etzpc: introduce ETZPC firewall controller driver

Gatien Chevallier
2023-12-12T15:27:01Z

ETZPC is a peripheral and memory firewall controller that filter accesses
based on Arm TrustZone secure state and Arm CPU privilege execution level.
It handles MCU isolation as well.

Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>
---

Changes in V2:
- Add controller name
- Driver is now a module_platform_driver
- Use error code returned by stm32_firewall_populate_bus()
- Fix license

MAINTAINERS | 1 +
drivers/bus/Makefile | 2 +-
drivers/bus/stm32_etzpc.c | 141 ++++++++++++++++++++++++++++++++++++++
3 files changed, 143 insertions(+), 1 deletion(-)
create mode 100644 drivers/bus/stm32_etzpc.c

diff --git a/MAINTAINERS b/MAINTAINERS
index a1152438b52d..b83b471c8b73 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -20433,6 +20433,7 @@ F: drivers/media/i2c/st-mipid02.c
ST STM32 FIREWALL
M: Gatien Chevallier <gatien.chevallier@foss.st.com>
S: Maintained
+F: drivers/bus/stm32_etzpc.c
F: drivers/bus/stm32_firewall.c
F: drivers/bus/stm32_rifsc.c

diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
index e50d18e1d141..cddd4984d6af 100644
--- a/drivers/bus/Makefile
+++ b/drivers/bus/Makefile
@@ -26,7 +26,7 @@ obj-$(CONFIG_OMAP_INTERCONNECT) += omap_l3_smx.o omap_l3_noc.o
obj-$(CONFIG_OMAP_OCP2SCP) += omap-ocp2scp.o
obj-$(CONFIG_QCOM_EBI2) += qcom-ebi2.o
obj-$(CONFIG_QCOM_SSC_BLOCK_BUS) += qcom-ssc-block-bus.o
-obj-$(CONFIG_STM32_FIREWALL) += stm32_firewall.o stm32_rifsc.o
+obj-$(CONFIG_STM32_FIREWALL) += stm32_firewall.o stm32_rifsc.o stm32_etzpc.o
obj-$(CONFIG_SUN50I_DE2_BUS) += sun50i-de2.o
obj-$(CONFIG_SUNXI_RSB) += sunxi-rsb.o
obj-$(CONFIG_OF) += simple-pm-bus.o
diff --git a/drivers/bus/stm32_etzpc.c b/drivers/bus/stm32_etzpc.c
new file mode 100644
index 000000000000..7fc0f16960be
--- /dev/null
+++ b/drivers/bus/stm32_etzpc.c
@@ -0,0 +1,141 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2023, STMicroelectronics - All Rights Reserved
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+
+#include "stm32_firewall.h"
+
+/*
+ * ETZPC registers
+ */
+#define ETZPC_DECPROT 0x10
+#define ETZPC_HWCFGR 0x3F0
+
+/*
+ * HWCFGR register
+ */
+#define ETZPC_HWCFGR_NUM_TZMA GENMASK(7, 0)
+#define ETZPC_HWCFGR_NUM_PER_SEC GENMASK(15, 8)
+#define ETZPC_HWCFGR_NUM_AHB_SEC GENMASK(23, 16)
+#define ETZPC_HWCFGR_CHUNKS1N4 GENMASK(31, 24)
+
+/*
+ * ETZPC miscellaneous
+ */
+#define ETZPC_PROT_MASK GENMASK(1, 0)
+#define ETZPC_PROT_A7NS 0x3
+#define ETZPC_DECPROT_SHIFT 1
+
+#define IDS_PER_DECPROT_REGS 16
+
+static int stm32_etzpc_grant_access(struct stm32_firewall_controller *ctrl, u32 firewall_id)
+{
+ u32 offset, reg_offset, sec_val;
+
+ if (firewall_id >= ctrl->max_entries) {
+ dev_err(ctrl->dev, "Invalid sys bus ID %u", firewall_id);
+ return -EINVAL;
+ }
+
+ /* Check access configuration, 16 peripherals per register */
+ reg_offset = ETZPC_DECPROT + 0x4 * (firewall_id / IDS_PER_DECPROT_REGS);
+ offset = (firewall_id % IDS_PER_DECPROT_REGS) << ETZPC_DECPROT_SHIFT;
+
+ /* Verify peripheral is non-secure and attributed to cortex A7 */
+ sec_val = (readl(ctrl->mmio + reg_offset) >> offset) & ETZPC_PROT_MASK;
+ if (sec_val != ETZPC_PROT_A7NS) {
+ dev_dbg(ctrl->dev, "Invalid bus configuration: reg_offset %#x, value %d\n",
+ reg_offset, sec_val);
+ return -EACCES;
+ }
+
+ return 0;
+}
+
+static void stm32_etzpc_release_access(struct stm32_firewall_controller *ctrl __maybe_unused,
+ u32 firewall_id __maybe_unused)
+{
+}
+
+static int stm32_etzpc_probe(struct platform_device *pdev)
+{
+ struct stm32_firewall_controller *etzpc_controller;
+ struct device_node *np = pdev->dev.of_node;
+ u32 nb_per, nb_master;
+ struct resource *res;
+ void __iomem *mmio;
+ int rc;
+
+ etzpc_controller = devm_kzalloc(&pdev->dev, sizeof(*etzpc_controller), GFP_KERNEL);
+ if (!etzpc_controller)
+ return -ENOMEM;
+
+ mmio = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+ if (IS_ERR(mmio))
+ return PTR_ERR(mmio);
+
+ etzpc_controller->dev = &pdev->dev;
+ etzpc_controller->mmio = mmio;
+ etzpc_controller->name = dev_driver_string(etzpc_controller->dev);
+ etzpc_controller->type = STM32_PERIPHERAL_FIREWALL | STM32_MEMORY_FIREWALL;
+ etzpc_controller->grant_access = stm32_etzpc_grant_access;
+ etzpc_controller->release_access = stm32_etzpc_release_access;
+
+ /* Get number of etzpc entries*/
+ nb_per = FIELD_GET(ETZPC_HWCFGR_NUM_PER_SEC,
+ readl(etzpc_controller->mmio + ETZPC_HWCFGR));
+ nb_master = FIELD_GET(ETZPC_HWCFGR_NUM_AHB_SEC,
+ readl(etzpc_controller->mmio + ETZPC_HWCFGR));
+ etzpc_controller->max_entries = nb_per + nb_master;
+
+ platform_set_drvdata(pdev, etzpc_controller);
+
+ rc = stm32_firewall_controller_register(etzpc_controller);
+ if (rc) {
+ dev_err(etzpc_controller->dev, "Couldn't register as a firewall controller: %d",
+ rc);
+ return rc;
+ }
+
+ rc = stm32_firewall_populate_bus(etzpc_controller);
+ if (rc) {
+ dev_err(etzpc_controller->dev, "Couldn't populate ETZPC bus: %d",
+ rc);
+ return rc;
+ }
+
+ /* Populate all allowed nodes */
+ return of_platform_populate(np, NULL, NULL, &pdev->dev);
+}
+
+static const struct of_device_id stm32_etzpc_of_match[] = {
+ { .compatible = "st,stm32-etzpc" },
+ {}
+};
+MODULE_DEVICE_TABLE(of, stm32_etzpc_of_match);
+
+static struct platform_driver stm32_etzpc_driver = {
+ .probe = stm32_etzpc_probe,
+ .driver = {
+ .name = "stm32-etzpc",
+ .of_match_table = stm32_etzpc_of_match,
+ },
+};
+module_platform_driver(stm32_etzpc_driver);
+
+MODULE_AUTHOR("Gatien Chevallier <gatien.chevallier@foss.st.com>");
+MODULE_DESCRIPTION("STMicroelectronics ETZPC driver");
+MODULE_LICENSE("GPL");