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