bootcount: add a DM RTC backing store for bootcount
This implements a driver using a RTC-based backing store for the DM
bootcount implementation. The node configuring this feature will be
compatible with 'u-boot,bootcount-rtc' and the underlying RTC device
shall be reference through the property 'rtc'. An offset into the RTC
device's register space can be provided through the 'offset' property.
Tested on a RK3399-Q7 on a Flamingo carrier board using the SRAM area
of the carrier board's RV3029 RTC.
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
diff --git a/drivers/bootcount/Kconfig b/drivers/bootcount/Kconfig
index 46571eb..b7c29f2 100644
--- a/drivers/bootcount/Kconfig
+++ b/drivers/bootcount/Kconfig
@@ -80,6 +80,26 @@
endchoice
+if DM_BOOTCOUNT
+
+menu "Backing stores for device-model backed bootcount"
+config DM_BOOTCOUNT_RTC
+ bool "Support RTC devices as a backing store for bootcount"
+ depends on DM_RTC
+ help
+ Enabled reading/writing the bootcount in a DM RTC device.
+ The wrapper device is to be specified with the compatible string
+ 'u-boot,bootcount-rtc' and the 'rtc'-property (a phandle pointing
+ to the underlying RTC device) and an optional 'offset' property
+ are supported.
+
+ Accesses to the backing store are performed using the write16
+ and read16 ops of DM RTC devices.
+
+endmenu
+
+endif
+
config BOOTCOUNT_BOOTLIMIT
int "Maximum number of reboot cycles allowed"
default 0
diff --git a/drivers/bootcount/Makefile b/drivers/bootcount/Makefile
index 81980b3..f9841d8 100644
--- a/drivers/bootcount/Makefile
+++ b/drivers/bootcount/Makefile
@@ -9,3 +9,4 @@
obj-$(CONFIG_BOOTCOUNT_EXT) += bootcount_ext.o
obj-$(CONFIG_DM_BOOTCOUNT) += bootcount-uclass.o
+obj-$(CONFIG_DM_BOOTCOUNT_RTC) += rtc.o
diff --git a/drivers/bootcount/rtc.c b/drivers/bootcount/rtc.c
new file mode 100644
index 0000000..db89fa3
--- /dev/null
+++ b/drivers/bootcount/rtc.c
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2018 Theobroma Systems Design und Consulting GmbH
+ */
+
+#include <common.h>
+#include <bootcount.h>
+#include <dm.h>
+#include <rtc.h>
+
+static const u8 bootcount_magic = 0xbc;
+
+struct bootcount_rtc_priv {
+ struct udevice *rtc;
+ u32 offset;
+};
+
+static int bootcount_rtc_set(struct udevice *dev, const u32 a)
+{
+ struct bootcount_rtc_priv *priv = dev_get_priv(dev);
+ const u16 val = bootcount_magic << 8 | (a & 0xff);
+
+ if (rtc_write16(priv->rtc, priv->offset, val) < 0) {
+ debug("%s: rtc_write16 failed\n", __func__);
+ return -EIO;
+ }
+
+ return 0;
+}
+
+static int bootcount_rtc_get(struct udevice *dev, u32 *a)
+{
+ struct bootcount_rtc_priv *priv = dev_get_priv(dev);
+ u16 val;
+
+ if (rtc_read16(priv->rtc, priv->offset, &val) < 0) {
+ debug("%s: rtc_write16 failed\n", __func__);
+ return -EIO;
+ }
+
+ if (val >> 8 == bootcount_magic) {
+ *a = val & 0xff;
+ return 0;
+ }
+
+ debug("%s: bootcount magic does not match on %04x\n", __func__, val);
+ return -EIO;
+}
+
+static int bootcount_rtc_probe(struct udevice *dev)
+{
+ struct ofnode_phandle_args phandle_args;
+ struct bootcount_rtc_priv *priv = dev_get_priv(dev);
+ struct udevice *rtc;
+
+ if (dev_read_phandle_with_args(dev, "rtc", NULL, 0, 0, &phandle_args)) {
+ debug("%s: rtc backing device not specified\n", dev->name);
+ return -ENOENT;
+ }
+
+ if (uclass_get_device_by_ofnode(UCLASS_RTC, phandle_args.node, &rtc)) {
+ debug("%s: could not get backing device\n", dev->name);
+ return -ENODEV;
+ }
+
+ priv->rtc = rtc;
+ priv->offset = dev_read_u32_default(dev, "offset", 0);
+
+ return 0;
+}
+
+static const struct bootcount_ops bootcount_rtc_ops = {
+ .get = bootcount_rtc_get,
+ .set = bootcount_rtc_set,
+};
+
+static const struct udevice_id bootcount_rtc_ids[] = {
+ { .compatible = "u-boot,bootcount-rtc" },
+ { }
+};
+
+U_BOOT_DRIVER(bootcount_rtc) = {
+ .name = "bootcount-rtc",
+ .id = UCLASS_BOOTCOUNT,
+ .priv_auto_alloc_size = sizeof(struct bootcount_rtc_priv),
+ .probe = bootcount_rtc_probe,
+ .of_match = bootcount_rtc_ids,
+ .ops = &bootcount_rtc_ops,
+};