stm32mp1: add watchdog support

Introduce driver for STM32 IWDG peripheral (Independent Watchdog).
It is configured according to device tree content and should be enabled
from there.
The watchdog is not started by default. It can be started after an HW
reset if the dedicated OTP is fused.

The watchdog also needs to be frozen if a debugger is attached.
This is done by configuring the correct bits in DBGMCU.
This configuration is allowed by checking BSEC properties.

An increase of BL2 size is also required when adding this new code.

Change-Id: Ide7535d717885ce2f9c387cf17afd8b5607f3e7f
Signed-off-by: Yann Gautier <yann.gautier@st.com>
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Signed-off-by: Nicolas Le Bayon <nicolas.le.bayon@st.com>

1 files changed, 150 insertions, 0 deletions

diff --git a/drivers/st/iwdg/stm32_iwdg.c b/drivers/st/iwdg/stm32_iwdg.c
new file mode 100644
index 00000000..ea6fbb2b
--- /dev/null
+++ b/drivers/st/iwdg/stm32_iwdg.c
@@ -0,0 +1,150 @@
+/*
+ * Copyright (c) 2017-2019, STMicroelectronics - All Rights Reserved
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <string.h>
+
+#include <libfdt.h>
+
+#include <platform_def.h>
+
+#include <arch_helpers.h>
+#include <common/debug.h>
+#include <drivers/arm/gicv2.h>
+#include <drivers/delay_timer.h>
+#include <drivers/st/stm32_iwdg.h>
+#include <drivers/st/stm32mp_clkfunc.h>
+#include <lib/mmio.h>
+#include <lib/utils.h>
+#include <plat/common/platform.h>
+
+/* IWDG registers offsets */
+#define IWDG_KR_OFFSET		0x00U
+
+/* Registers values */
+#define IWDG_KR_RELOAD_KEY	0xAAAA
+
+struct stm32_iwdg_instance {
+	uintptr_t base;
+	unsigned long clock;
+	uint8_t flags;
+	int num_irq;
+};
+
+static struct stm32_iwdg_instance stm32_iwdg[IWDG_MAX_INSTANCE];
+
+static int stm32_iwdg_get_dt_node(struct dt_node_info *info, int offset)
+{
+	int node;
+
+	node = dt_get_node(info, offset, DT_IWDG_COMPAT);
+	if (node < 0) {
+		if (offset == -1) {
+			VERBOSE("%s: No IDWG found\n", __func__);
+		}
+		return -FDT_ERR_NOTFOUND;
+	}
+
+	return node;
+}
+
+void stm32_iwdg_refresh(void)
+{
+	uint8_t i;
+
+	for (i = 0U; i < IWDG_MAX_INSTANCE; i++) {
+		struct stm32_iwdg_instance *iwdg = &stm32_iwdg[i];
+
+		/* 0x00000000 is not a valid address for IWDG peripherals */
+		if (iwdg->base != 0U) {
+			stm32mp_clk_enable(iwdg->clock);
+
+			mmio_write_32(iwdg->base + IWDG_KR_OFFSET,
+				      IWDG_KR_RELOAD_KEY);
+
+			stm32mp_clk_disable(iwdg->clock);
+		}
+	}
+}
+
+int stm32_iwdg_init(void)
+{
+	int node = -1;
+	struct dt_node_info dt_info;
+	void *fdt;
+	uint32_t __unused count = 0;
+
+	if (fdt_get_address(&fdt) == 0) {
+		panic();
+	}
+
+	for (node = stm32_iwdg_get_dt_node(&dt_info, node);
+	     node != -FDT_ERR_NOTFOUND;
+	     node = stm32_iwdg_get_dt_node(&dt_info, node)) {
+		struct stm32_iwdg_instance *iwdg;
+		uint32_t hw_init;
+		uint32_t idx;
+
+		count++;
+
+		idx = stm32_iwdg_get_instance(dt_info.base);
+		iwdg = &stm32_iwdg[idx];
+		iwdg->base = dt_info.base;
+		iwdg->clock = (unsigned long)dt_info.clock;
+
+		/* DT can specify low power cases */
+		if (fdt_getprop(fdt, node, "stm32,enable-on-stop", NULL) ==
+		    NULL) {
+			iwdg->flags |= IWDG_DISABLE_ON_STOP;
+		}
+
+		if (fdt_getprop(fdt, node, "stm32,enable-on-standby", NULL) ==
+		    NULL) {
+			iwdg->flags |= IWDG_DISABLE_ON_STANDBY;
+		}
+
+		/* Explicit list of supported bit flags */
+		hw_init = stm32_iwdg_get_otp_config(idx);
+
+		if ((hw_init & IWDG_HW_ENABLED) != 0) {
+			if (dt_info.status == DT_DISABLED) {
+				ERROR("OTP enabled but iwdg%u DT-disabled\n",
+				      idx + 1U);
+				panic();
+			}
+			iwdg->flags |= IWDG_HW_ENABLED;
+		}
+
+		if (dt_info.status == DT_DISABLED) {
+			zeromem((void *)iwdg,
+				sizeof(struct stm32_iwdg_instance));
+			continue;
+		}
+
+		if ((hw_init & IWDG_DISABLE_ON_STOP) != 0) {
+			iwdg->flags |= IWDG_DISABLE_ON_STOP;
+		}
+
+		if ((hw_init & IWDG_DISABLE_ON_STANDBY) != 0) {
+			iwdg->flags |= IWDG_DISABLE_ON_STANDBY;
+		}
+
+		VERBOSE("IWDG%u found, %ssecure\n", idx + 1U,
+			((dt_info.status & DT_NON_SECURE) != 0) ?
+			"non-" : "");
+
+#if defined(IMAGE_BL2)
+		if (stm32_iwdg_shadow_update(idx, iwdg->flags) != BSEC_OK) {
+			return -1;
+		}
+#endif
+	}
+
+	VERBOSE("%u IWDG instance%s found\n", count, (count > 1U) ? "s" : "");
+
+	return 0;
+}