[PATCH v3] watchdog: Add a watchdog driver for Raspberry Pi boards
ETIENNE DUBLE
etienne.duble at imag.fr
Wed Jan 25 10:57:28 CET 2023
This driver supports the bcm2835 watchdog found on
Raspberry Pi boards.
It is derived from the Linux driver and was tested
on two Raspberry Pi board versions (B+ and 3B+).
Signed-off-by: Etienne Dublé <etienne.duble at imag.fr>
---
Changes for v2:
- fixed whitespaces in email
- moved a static variable to the priv struct
Changes for v3:
- used the max timeout value the hardware supports
- turned the warning to a one-line message
drivers/watchdog/Kconfig | 9 +++
drivers/watchdog/Makefile | 1 +
drivers/watchdog/bcm2835_wdt.c | 132 +++++++++++++++++++++++++++++++++
3 files changed, 142 insertions(+)
create mode 100644 drivers/watchdog/bcm2835_wdt.c
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index f1b1cf63ca..06c0d630c8 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -30,6 +30,7 @@ config WATCHDOG_TIMEOUT_MSECS
default 128000 if ARCH_MX7 || ARCH_VF610
default 30000 if ARCH_SOCFPGA
default 16000 if ARCH_SUNXI
+ default 15000 if ARCH_BCM283X
default 60000
help
Watchdog timeout in msec
@@ -326,6 +327,14 @@ config WDT_SUNXI
help
Enable support for the watchdog timer in Allwinner sunxi SoCs.
+config WDT_BCM2835
+ bool "Broadcom 2835 watchdog timer support"
+ depends on WDT && ARCH_BCM283X
+ default y
+ help
+ Enable support for the watchdog timer in Broadcom 283X SoCs such
+ as Raspberry Pi boards.
+
config XILINX_TB_WATCHDOG
bool "Xilinx Axi watchdog timer support"
depends on WDT
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 446d961d7d..f99915960c 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -21,6 +21,7 @@ obj-$(CONFIG_WDT_APPLE) += apple_wdt.o
obj-$(CONFIG_WDT_ARMADA_37XX) += armada-37xx-wdt.o
obj-$(CONFIG_WDT_ASPEED) += ast_wdt.o
obj-$(CONFIG_WDT_AST2600) += ast2600_wdt.o
+obj-$(CONFIG_WDT_BCM2835) += bcm2835_wdt.o
obj-$(CONFIG_WDT_BCM6345) += bcm6345_wdt.o
obj-$(CONFIG_WDT_BOOKE) += booke_wdt.o
obj-$(CONFIG_WDT_CORTINA) += cortina_wdt.o
diff --git a/drivers/watchdog/bcm2835_wdt.c b/drivers/watchdog/bcm2835_wdt.c
new file mode 100644
index 0000000000..3c1ead3dda
--- /dev/null
+++ b/drivers/watchdog/bcm2835_wdt.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2013 Lubomir Rintel <lkundrak at v3.sk>
+ * Copyright (C) 2023 Etienne Dublé (CNRS) <etienne.duble at imag.fr>
+ *
+ * This code is mostly derived from the linux driver.
+ */
+
+#include <dm.h>
+#include <wdt.h>
+#include <asm/io.h>
+#include <linux/delay.h>
+
+#define PM_RSTC 0x1c
+#define PM_WDOG 0x24
+
+#define PM_PASSWORD 0x5a000000
+
+/* The hardware supports a maximum timeout value of 0xfffff ticks
+ * (just below 16 seconds).
+ */
+#define PM_WDOG_MAX_TICKS 0x000fffff
+#define PM_RSTC_WRCFG_CLR 0xffffffcf
+#define PM_RSTC_WRCFG_FULL_RESET 0x00000020
+#define PM_RSTC_RESET 0x00000102
+
+#define MS_TO_WDOG_TICKS(x) (((x) << 16) / 1000)
+
+struct bcm2835_wdt_priv {
+ void __iomem *base;
+ u64 timeout_ticks;
+};
+
+static int bcm2835_wdt_start_ticks(struct udevice *dev,
+ u64 timeout_ticks, ulong flags)
+{
+ struct bcm2835_wdt_priv *priv = dev_get_priv(dev);
+ void __iomem *base = priv->base;
+ u32 cur;
+
+ writel(PM_PASSWORD | timeout_ticks, base + PM_WDOG);
+ cur = readl(base + PM_RSTC);
+ writel(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) | PM_RSTC_WRCFG_FULL_RESET,
+ base + PM_RSTC);
+
+ return 0;
+}
+
+static int bcm2835_wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
+{
+ struct bcm2835_wdt_priv *priv = dev_get_priv(dev);
+
+ priv->timeout_ticks = MS_TO_WDOG_TICKS(timeout_ms);
+
+ if (priv->timeout_ticks > PM_WDOG_MAX_TICKS) {
+ printf("bcm2835_wdt: the timeout value is too high, using ~16s instead.\n");
+ priv->timeout_ticks = PM_WDOG_MAX_TICKS;
+ }
+
+ return bcm2835_wdt_start_ticks(dev, priv->timeout_ticks, flags);
+}
+
+static int bcm2835_wdt_reset(struct udevice *dev)
+{
+ struct bcm2835_wdt_priv *priv = dev_get_priv(dev);
+
+ /* restart the timer with the value of priv->timeout_ticks
+ * saved from the last bcm2835_wdt_start() call.
+ */
+ return bcm2835_wdt_start_ticks(dev, priv->timeout_ticks, 0);
+}
+
+static int bcm2835_wdt_stop(struct udevice *dev)
+{
+ struct bcm2835_wdt_priv *priv = dev_get_priv(dev);
+ void __iomem *base = priv->base;
+
+ writel(PM_PASSWORD | PM_RSTC_RESET, base + PM_RSTC);
+
+ return 0;
+}
+
+static int bcm2835_wdt_expire_now(struct udevice *dev, ulong flags)
+{
+ int ret;
+
+ /* use a timeout of 10 ticks (~150us) */
+ ret = bcm2835_wdt_start_ticks(dev, 10, flags);
+ if (ret)
+ return ret;
+
+ mdelay(500);
+
+ return 0;
+}
+
+static const struct wdt_ops bcm2835_wdt_ops = {
+ .reset = bcm2835_wdt_reset,
+ .start = bcm2835_wdt_start,
+ .stop = bcm2835_wdt_stop,
+ .expire_now = bcm2835_wdt_expire_now,
+};
+
+static const struct udevice_id bcm2835_wdt_ids[] = {
+ { .compatible = "brcm,bcm2835-pm" },
+ { .compatible = "brcm,bcm2835-pm-wdt" },
+ { /* sentinel */ }
+};
+
+static int bcm2835_wdt_probe(struct udevice *dev)
+{
+ struct bcm2835_wdt_priv *priv = dev_get_priv(dev);
+
+ priv->base = dev_remap_addr(dev);
+ if (!priv->base)
+ return -EINVAL;
+
+ priv->timeout_ticks = PM_WDOG_MAX_TICKS;
+
+ bcm2835_wdt_stop(dev);
+
+ return 0;
+}
+
+U_BOOT_DRIVER(bcm2835_wdt) = {
+ .name = "bcm2835_wdt",
+ .id = UCLASS_WDT,
+ .of_match = bcm2835_wdt_ids,
+ .probe = bcm2835_wdt_probe,
+ .priv_auto = sizeof(struct bcm2835_wdt_priv),
+ .ops = &bcm2835_wdt_ops,
+};
--
2.34.1
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