Add a fault injector simulating a Kernel panic happening after starting
a transfer. Read the docs for its usage.
Signed-off-by: Wolfram Sang <wsa+rene...@sang-engineering.com>
---
Documentation/i2c/gpio-fault-injection | 26 ++++++++++++++++++++++++++
drivers/i2c/busses/i2c-gpio.c | 31 ++++++++++++++++++++++++++++++-
2 files changed, 56 insertions(+), 1 deletion(-)
diff --git a/Documentation/i2c/gpio-fault-injection
b/Documentation/i2c/gpio-fault-injection
index 1f1bb96a64bd..c87f416d53dd 100644
--- a/Documentation/i2c/gpio-fault-injection
+++ b/Documentation/i2c/gpio-fault-injection
@@ -108,3 +108,29 @@ idle bus is:
# echo 200 > lose_arbitration &
# i2cget -y <bus_to_test> 0x3f
+
+Panic during transfer
+=====================
+
+This fault injector will create a Kernel panic once the master under test
+started a transfer. This usually means that the state machine of the bus master
+driver will be ungracefully interrupted and the bus may end up in an unusual
+state. Use this to check if your shutdown/reboot/boot code can handle this
+scenario.
+
+"inject_panic"
+--------------
+
+This file is write only and you need to write the delay between the detected
+start of a transmission and the induced Kernel panic (in µs, maximum is 100ms).
+The calling process will then sleep and wait for the next bus clock. The
+process is interruptible, though.
+
+Start of a transfer is detected by waiting for SCL going down by the master
+under test. A good starting point for using this fault injector is:
+
+# echo 0 > inject_panic &
+# i2cget -y <bus_to_test> <some_address>
+
+Note that there doesn't need to be a device listening to the address you are
+using. Results may vary depending on that, though.
diff --git a/drivers/i2c/busses/i2c-gpio.c b/drivers/i2c/busses/i2c-gpio.c
index 76e43783f50f..bba5c4627de3 100644
--- a/drivers/i2c/busses/i2c-gpio.c
+++ b/drivers/i2c/busses/i2c-gpio.c
@@ -231,6 +231,32 @@ static int fops_lose_arbitration_set(void *data, u64
duration)
}
DEFINE_DEBUGFS_ATTRIBUTE(fops_lose_arbitration, NULL,
fops_lose_arbitration_set, "%llu\n");
+static irqreturn_t inject_panic_irq(int irq, void *dev_id)
+{
+ struct i2c_gpio_private_data *priv = dev_id;
+
+ udelay(priv->scl_irq_data);
+ panic("I2C fault injector induced panic");
+
+ return IRQ_HANDLED;
+}
+
+static int fops_inject_panic_set(void *data, u64 duration)
+{
+ struct i2c_gpio_private_data *priv = data;
+
+ if (duration > 100 * 1000)
+ return -EINVAL;
+
+ priv->scl_irq_data = duration;
+ /*
+ * Interrupt on falling SCL. This ensures that the master under test has
+ * really started the transfer.
+ */
+ return i2c_gpio_fi_act_on_scl_irq(priv, inject_panic_irq);
+}
+DEFINE_DEBUGFS_ATTRIBUTE(fops_inject_panic, NULL, fops_inject_panic_set,
"%llu\n");
+
static void i2c_gpio_fault_injector_init(struct platform_device *pdev)
{
struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev);
@@ -256,9 +282,12 @@ static void i2c_gpio_fault_injector_init(struct
platform_device *pdev)
priv, &fops_incomplete_addr_phase);
debugfs_create_file_unsafe("incomplete_write_byte", 0200,
priv->debug_dir,
priv, &fops_incomplete_write_byte);
- if (priv->bit_data.getscl)
+ if (priv->bit_data.getscl) {
+ debugfs_create_file_unsafe("inject_panic", 0200,
priv->debug_dir,
+ priv, &fops_inject_panic);
debugfs_create_file_unsafe("lose_arbitration", 0200,
priv->debug_dir,
priv, &fops_lose_arbitration);
+ }
debugfs_create_file_unsafe("scl", 0600, priv->debug_dir, priv,
&fops_scl);
debugfs_create_file_unsafe("sda", 0600, priv->debug_dir, priv,
&fops_sda);
}
--
2.11.0
