diff options
| -rw-r--r-- | Documentation/i2c/gpio-fault-injection | 26 | ||||
| -rw-r--r-- | drivers/i2c/busses/i2c-gpio.c | 31 |
2 files changed, 56 insertions, 1 deletions
diff --git a/Documentation/i2c/gpio-fault-injection b/Documentation/i2c/gpio-fault-injection index 1f1bb96a64bd3..c87f416d53dd2 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 76e43783f50f9..bba5c4627de3c 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); } |