watchdog: rti_wdt: Add support for loading firmware

To avoid the need of extra boot scripting on AM65x for loading a
watchdog firmware, add the required rproc init and loading logic for the
first R5F core to the watchdog start handler. In case the R5F cluster is
in lock-step mode, also initialize the second core. The firmware itself
is embedded into U-Boot binary to ease access to it and ensure it is
properly hashed in case of secure boot.

One possible firmware source is https://github.com/siemens/k3-rti-wdt.

The board is responsible for providing the firmware as additional
loadable via the U-Boot fit image. The driver will pick up its location
from /fit-images/k3-rti-wdt-firmware then.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index eaa6f16..7d2d6ea 100644 (file)
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -218,6 +218,26 @@ config WDT_K3_RTI
          Say Y here if you want to include support for the K3 watchdog
          timer (RTI module) available in the K3 generation of processors.
 
+if WDT_K3_RTI
+
+config WDT_K3_RTI_LOAD_FW
+       bool "Load watchdog firmware"
+       depends on REMOTEPROC
+       help
+         Automatically load the specified firmware image into the MCU R5F
+         core 0. On the AM65x, this firmware is supposed to handle the expiry
+         of the watchdog timer, typically by resetting the system.
+
+config WDT_K3_RTI_FW_FILE
+       string "Watchdog firmware image file"
+       default "k3-rti-wdt.fw"
+       depends on WDT_K3_RTI_LOAD_FW
+       help
+         Firmware image to be embedded into U-Boot and loaded on watchdog
+         start.
+
+endif
+
 config WDT_SANDBOX
        bool "Enable Watchdog Timer support for Sandbox"
        depends on SANDBOX && WDT

diff --git a/drivers/watchdog/rti_wdt.c b/drivers/watchdog/rti_wdt.c
index 8335b20..253286d 100644 (file)
--- a/drivers/watchdog/rti_wdt.c
+++ b/drivers/watchdog/rti_wdt.c
@@ -11,9 +11,11 @@
 #include <common.h>
 #include <clk.h>
 #include <dm.h>
+#include <dm/device_compat.h>
 #include <power-domain.h>
 #include <wdt.h>
 #include <asm/io.h>
+#include <remoteproc.h>
 
 /* Timer register set definition */
 #define RTIDWDCTRL             0x90
@@ -42,6 +44,88 @@ struct rti_wdt_priv {
        unsigned int clk_khz;
 };
 
+#ifdef CONFIG_WDT_K3_RTI_LOAD_FW
+#define RTI_WDT_FIT_PATH       "/fit-images/k3-rti-wdt-firmware"
+
+static int rti_wdt_load_fw(struct udevice *dev)
+{
+       struct udevice *rproc_dev;
+       int primary_core, ret;
+       u32 cluster_mode;
+       ofnode node;
+       u64 rti_wdt_fw;
+       u32 rti_wdt_fw_size;
+
+       node = ofnode_path(RTI_WDT_FIT_PATH);
+       if (!ofnode_valid(node))
+               goto fit_error;
+
+       ret = ofnode_read_u64(node, "load", &rti_wdt_fw);
+       if (ret)
+               goto fit_error;
+       ret = ofnode_read_u32(node, "size", &rti_wdt_fw_size);
+       if (ret)
+               goto fit_error;
+
+       node = ofnode_by_compatible(ofnode_null(), "ti,am654-r5fss");
+       if (!ofnode_valid(node))
+               goto dt_error;
+
+       ret = ofnode_read_u32(node, "ti,cluster-mode", &cluster_mode);
+       if (ret)
+               cluster_mode = 1;
+
+       node = ofnode_by_compatible(node, "ti,am654-r5f");
+       if (!ofnode_valid(node))
+               goto dt_error;
+
+       ret = uclass_get_device_by_ofnode(UCLASS_REMOTEPROC, node, &rproc_dev);
+       if (ret)
+               return ret;
+
+       primary_core = dev_seq(rproc_dev);
+
+       ret = rproc_dev_init(primary_core);
+       if (ret)
+               goto fw_error;
+
+       if (cluster_mode == 1) {
+               ret = rproc_dev_init(primary_core + 1);
+               if (ret)
+                       goto fw_error;
+       }
+
+       ret = rproc_load(primary_core, (ulong)rti_wdt_fw,
+                        rti_wdt_fw_size);
+       if (ret)
+               goto fw_error;
+
+       ret = rproc_start(primary_core);
+       if (ret)
+               goto fw_error;
+
+       return 0;
+
+fit_error:
+       dev_err(dev, "No loadable firmware found under %s\n", RTI_WDT_FIT_PATH);
+       return -ENOENT;
+
+dt_error:
+       dev_err(dev, "No compatible firmware target processor found\n");
+       return -ENODEV;
+
+fw_error:
+       dev_err(dev, "Failed to load watchdog firmware into remote processor %d\n",
+               primary_core);
+       return ret;
+}
+#else
+static inline int rti_wdt_load_fw(struct udevice *dev)
+{
+       return 0;
+}
+#endif
+
 static int rti_wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
 {
        struct rti_wdt_priv *priv = dev_get_priv(dev);
@@ -51,6 +135,10 @@ static int rti_wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
        if (readl(priv->regs + RTIDWDCTRL) == WDENABLE_KEY)
                return -EBUSY;
 
+       ret = rti_wdt_load_fw(dev);
+       if (ret < 0)
+               return ret;
+
        timer_margin = timeout_ms * priv->clk_khz / 1000;
        timer_margin >>= WDT_PRELOAD_SHIFT;
        if (timer_margin > WDT_PRELOAD_MAX)