[PATCH v4 3/3] reboot-mode: read the boot mode from RTC memory

Nandor Han
2021-06-10T13:57:40Z

RTC devices could provide battery-backed memory that can be used for
storing the reboot mode magic value.

Add a new reboot-mode back-end that uses RTC to store the reboot-mode
magic value. The driver also supports both endianness modes.

Signed-off-by: Nandor Han <nandor.han@vaisala.com>
---
arch/sandbox/dts/test.dts | 10 ++
configs/sandbox_defconfig | 1 +
.../reboot-mode/reboot-mode-rtc.txt | 22 +++
drivers/reboot-mode/Kconfig | 9 ++
drivers/reboot-mode/Makefile | 1 +
drivers/reboot-mode/reboot-mode-rtc.c | 127 ++++++++++++++++++
include/reboot-mode/reboot-mode-rtc.h | 16 +++
test/dm/reboot-mode.c | 29 ++++
8 files changed, 215 insertions(+)
create mode 100644 doc/device-tree-bindings/reboot-mode/reboot-mode-rtc.txt
create mode 100644 drivers/reboot-mode/reboot-mode-rtc.c
create mode 100644 include/reboot-mode/reboot-mode-rtc.h

diff --git a/arch/sandbox/dts/test.dts b/arch/sandbox/dts/test.dts
index bd261818af..66ce21cd7b 100644
--- a/arch/sandbox/dts/test.dts
+++ b/arch/sandbox/dts/test.dts
@@ -67,6 +67,16 @@
mode-download = <0x03>;
};

+ reboot_mode1: reboot-mode@14 {
+ compatible = "reboot-mode-rtc";
+ rtc = <&rtc_0>;
+ reg = <0x30 4>;
+ u-boot,env-variable = "bootstatus";
+ big-endian;
+ mode-test = <0x21969147>;
+ mode-download = <0x51939147>;
+ };
+
audio: audio-codec {
compatible = "sandbox,audio-codec";
#sound-dai-cells = <1>;
diff --git a/configs/sandbox_defconfig b/configs/sandbox_defconfig
index fed187e2a0..199b7539d5 100644
--- a/configs/sandbox_defconfig
+++ b/configs/sandbox_defconfig
@@ -289,3 +289,4 @@ CONFIG_UT_TIME=y
CONFIG_UT_DM=y
CONFIG_DM_REBOOT_MODE=y
CONFIG_DM_REBOOT_MODE_GPIO=y
+CONFIG_DM_REBOOT_MODE_RTC=y
diff --git a/doc/device-tree-bindings/reboot-mode/reboot-mode-rtc.txt b/doc/device-tree-bindings/reboot-mode/reboot-mode-rtc.txt
new file mode 100644
index 0000000000..23aa12c88c
--- /dev/null
+++ b/doc/device-tree-bindings/reboot-mode/reboot-mode-rtc.txt
@@ -0,0 +1,22 @@
+RTC Reboot Mode Configuration
+
+Required Properties:
+- compatible: must be "reboot-mode-rtc".
+- rtc: reference to the rtc device used.
+- reg: start register and the number of bytes used. Maximum 4 bytes supported.
+- modes: list of properties that define the modes and associated unique ids.
+
+Optional Properties:
+- u-boot,env-variable: used to save the reboot mode (default: reboot-mode).
+- big-endian: if the magic value is stored in big-endian. (default: false).
+
+Example:
+ reboot-mode-rtc {
+ compatible = "reboot-mode-rtc";
+ rtc = <&rtc_0>;
+ reg = <0x14 4>;
+ u-boot,env-variable = "bootstatus";
+ big-endian;
+ modes-test = <0x21969147>;
+ modes-download = <0x51939147>;
+ };
diff --git a/drivers/reboot-mode/Kconfig b/drivers/reboot-mode/Kconfig
index ff65e2031a..ac67bfcef6 100644
--- a/drivers/reboot-mode/Kconfig
+++ b/drivers/reboot-mode/Kconfig
@@ -24,4 +24,13 @@ config DM_REBOOT_MODE_GPIO
a device in a specific mode by using a GPIO that can be controlled
outside U-Boot.

+config DM_REBOOT_MODE_RTC
+ bool "Use RTC as reboot mode backend"
+ depends on DM_REBOOT_MODE
+ default n
+ help
+ Use RTC non volatile memory to control the reboot mode. This will allow users to boot
+ a device in a specific mode by using a register(s) that can be controlled
+ outside U-Boot (e.g. Kernel).
+
endmenu
diff --git a/drivers/reboot-mode/Makefile b/drivers/reboot-mode/Makefile
index 04917be4f4..2c13780ced 100644
--- a/drivers/reboot-mode/Makefile
+++ b/drivers/reboot-mode/Makefile
@@ -6,3 +6,4 @@

obj-$(CONFIG_DM_REBOOT_MODE) += reboot-mode-uclass.o
obj-$(CONFIG_DM_REBOOT_MODE_GPIO) += reboot-mode-gpio.o
+obj-$(CONFIG_DM_REBOOT_MODE_RTC) += reboot-mode-rtc.o
diff --git a/drivers/reboot-mode/reboot-mode-rtc.c b/drivers/reboot-mode/reboot-mode-rtc.c
new file mode 100644
index 0000000000..972d0cdbcb
--- /dev/null
+++ b/drivers/reboot-mode/reboot-mode-rtc.c
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c), Vaisala Oyj
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <dm/device_compat.h>
+#include <reboot-mode/reboot-mode-rtc.h>
+#include <reboot-mode/reboot-mode.h>
+#include <rtc.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+static int reboot_mode_get(struct udevice *dev, u32 *buf)
+{
+ if (!buf)
+ return -EINVAL;
+
+ int ret;
+ u8 *val = (u8 *)buf;
+ struct reboot_mode_rtc_platdata *plat_data;
+
+ plat_data = dev_get_plat(dev);
+ if (!plat_data)
+ return -EINVAL;
+
+ for (int i = 0; i < plat_data->size; i++) {
+ ret = rtc_read8(plat_data->rtc, plat_data->addr + i);
+ if (ret < 0)
+ return ret;
+
+ val[i] = ret;
+ }
+
+ if (plat_data->is_big_endian)
+ *buf = __be32_to_cpu(*buf);
+ else
+ *buf = __le32_to_cpu(*buf);
+
+ return 0;
+}
+
+static int reboot_mode_set(struct udevice *dev, u32 buf)
+{
+ int ret;
+ u8 *val;
+ struct reboot_mode_rtc_platdata *plat_data;
+
+ plat_data = dev_get_plat(dev);
+ if (!plat_data)
+ return -EINVAL;
+
+ if (plat_data->is_big_endian)
+ buf = __cpu_to_be32(buf);
+ else
+ buf = __cpu_to_le32(buf);
+
+ val = (u8 *)&buf;
+
+ for (int i = 0; i < plat_data->size; i++) {
+ ret = rtc_write8(plat_data->rtc, (plat_data->addr + i), val[i]);
+ if (ret < 0)
+ return ret;
+ }
+
+ return 0;
+}
+
+#if CONFIG_IS_ENABLED(OF_CONTROL)
+static int reboot_mode_ofdata_to_platdata(struct udevice *dev)
+{
+ struct ofnode_phandle_args phandle_args;
+ struct reboot_mode_rtc_platdata *plat_data;
+
+ plat_data = dev_get_plat(dev);
+ if (!plat_data)
+ return -EINVAL;
+
+ if (dev_read_phandle_with_args(dev, "rtc", NULL, 0, 0, &phandle_args)) {
+ dev_err(dev, "RTC device not specified\n");
+ return -ENOENT;
+ }
+
+ if (uclass_get_device_by_ofnode(UCLASS_RTC, phandle_args.node,
+ &plat_data->rtc)) {
+ dev_err(dev, "could not get the RTC device\n");
+ return -ENODEV;
+ }
+
+ plat_data->addr =
+ dev_read_addr_size_index(dev, 0, (fdt_size_t *)&plat_data->size);
+ if (plat_data->addr == FDT_ADDR_T_NONE) {
+ dev_err(dev, "Invalid RTC address\n");
+ return -EINVAL;
+ }
+ if (plat_data->size > sizeof(u32)) {
+ dev_err(dev, "Invalid reg size\n");
+ return -EINVAL;
+ }
+
+ plat_data->is_big_endian = ofnode_read_bool(dev_ofnode(dev), "big-endian");
+
+ return 0;
+}
+
+static const struct udevice_id reboot_mode_ids[] = {
+ { .compatible = "reboot-mode-rtc", 0 },
+ {}
+};
+#endif
+
+static const struct reboot_mode_ops reboot_mode_rtc_ops = {
+ .get = reboot_mode_get,
+ .set = reboot_mode_set,
+};
+
+U_BOOT_DRIVER(reboot_mode_rtc) = {
+ .name = "reboot-mode-rtc",
+ .id = UCLASS_REBOOT_MODE,
+#if CONFIG_IS_ENABLED(OF_CONTROL)
+ .of_match = reboot_mode_ids,
+ .of_to_plat = reboot_mode_ofdata_to_platdata,
+#endif
+ .plat_auto = sizeof(struct reboot_mode_rtc_platdata),
+ .ops = &reboot_mode_rtc_ops,
+};
diff --git a/include/reboot-mode/reboot-mode-rtc.h b/include/reboot-mode/reboot-mode-rtc.h
new file mode 100644
index 0000000000..3613678f63
--- /dev/null
+++ b/include/reboot-mode/reboot-mode-rtc.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (c), Vaisala Oyj
+ */
+
+#ifndef REBOOT_MODE_REBOOT_MODE_RTC_H_
+#define REBOOT_MODE_REBOOT_MODE_RTC_H_
+
+struct reboot_mode_rtc_platdata {
+ struct udevice *rtc;
+ bool is_big_endian;
+ int addr;
+ size_t size;
+};
+
+#endif /* REBOOT_MODE_REBOOT_MODE_RTC_H_ */
diff --git a/test/dm/reboot-mode.c b/test/dm/reboot-mode.c
index 66aa4793f7..fbb9c3a542 100644
--- a/test/dm/reboot-mode.c
+++ b/test/dm/reboot-mode.c
@@ -9,10 +9,13 @@
#include <env.h>
#include <log.h>
#include <asm/gpio.h>
+#include <asm/rtc.h>
#include <asm/test.h>
#include <dm/test.h>
#include <test/test.h>
#include <test/ut.h>
+#include <rtc.h>
+#include <linux/byteorder/generic.h>

static int dm_test_reboot_mode_gpio(struct unit_test_state *uts)
{
@@ -40,3 +43,29 @@ static int dm_test_reboot_mode_gpio(struct unit_test_state *uts)

DM_TEST(dm_test_reboot_mode_gpio,
UT_TESTF_PROBE_TEST | UT_TESTF_SCAN_FDT | UT_TESTF_FLAT_TREE);
+
+static int dm_test_reboot_mode_rtc(struct unit_test_state *uts)
+{
+ struct udevice *rtc_dev;
+ struct udevice *rm_dev;
+ u32 read_val;
+ u32 test_magic_val = cpu_to_be32(0x21969147);
+
+ uclass_get_device_by_name(UCLASS_RTC, "rtc@43",
+ &rtc_dev);
+ dm_rtc_write(rtc_dev, REG_AUX0, (u8 *)&test_magic_val, 4);
+
+ ut_assertok(uclass_get_device_by_name(UCLASS_REBOOT_MODE,
+ "reboot-mode@14", &rm_dev));
+ ut_assertok(dm_reboot_mode_update(rm_dev));
+
+ ut_asserteq_str("test", env_get("bootstatus"));
+
+ dm_rtc_read(rtc_dev, REG_AUX0, (u8 *)&read_val, 4);
+ ut_asserteq(read_val, 0);
+
+ return 0;
+}
+
+DM_TEST(dm_test_reboot_mode_rtc,
+ UT_TESTF_PROBE_TEST | UT_TESTF_SCAN_FDT | UT_TESTF_FLAT_TREE);
--
2.26.3