* [PATCH v2 1/2] i2c: gpio: fault-injector: add 'lose_arbitration' injector
2019-02-19 16:39 [PATCH v2 0/2] i2c: gpio: fault-injector: add two new injectors Wolfram Sang
@ 2019-02-19 16:39 ` Wolfram Sang
2019-02-23 9:36 ` Wolfram Sang
2019-02-19 16:39 ` [PATCH v2 2/2] i2c: gpio: fault-injector: add 'inject_panic' injector Wolfram Sang
1 sibling, 1 reply; 5+ messages in thread
From: Wolfram Sang @ 2019-02-19 16:39 UTC (permalink / raw)
To: linux-i2c; +Cc: linux-renesas-soc, Geert Uytterhoeven, Wolfram Sang
Add a fault injector simulating 'arbitration lost' from multi-master
setups. Read the docs for its usage.
A helper function for future fault injectors using SCL interrupts is
created to achieve this.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
Documentation/i2c/gpio-fault-injection | 25 ++++++++++++
drivers/i2c/busses/i2c-gpio.c | 74 ++++++++++++++++++++++++++++++++++
2 files changed, 99 insertions(+)
diff --git a/Documentation/i2c/gpio-fault-injection b/Documentation/i2c/gpio-fault-injection
index 1a44e3edc0c4..1f1bb96a64bd 100644
--- a/Documentation/i2c/gpio-fault-injection
+++ b/Documentation/i2c/gpio-fault-injection
@@ -83,3 +83,28 @@ This is why bus recovery (up to 9 clock pulses) must either check SDA or send
additional STOP conditions to ensure the bus has been released. Otherwise
random data will be written to a device!
+Lost arbitration
+================
+
+Here, we want to simulate the condition where the master under test loses the
+bus arbitration against another master in a multi-master setup.
+
+"lose_arbitration"
+------------------
+
+This file is write only and you need to write the duration of the arbitration
+intereference (in µs, maximum is 100ms). The calling process will then sleep
+and wait for the next bus clock. The process is interruptible, though.
+
+Arbitration lost is achieved by waiting for SCL going down by the master under
+test and then pulling SDA low for some time. So, the I2C address sent out
+should be corrupted and that should be detected properly. That means that the
+address sent out should have a lot of '1' bits to be able to detect corruption.
+There doesn't need to be a device at this address because arbitration lost
+should be detected beforehand. Also note, that SCL going down is monitored
+using interrupts, so the interrupt latency might cause the first bits to be not
+corrupted. A good starting point for using this fault injector on an otherwise
+idle bus is:
+
+# echo 200 > lose_arbitration &
+# i2cget -y <bus_to_test> 0x3f
diff --git a/drivers/i2c/busses/i2c-gpio.c b/drivers/i2c/busses/i2c-gpio.c
index 2d532cc042f5..76e43783f50f 100644
--- a/drivers/i2c/busses/i2c-gpio.c
+++ b/drivers/i2c/busses/i2c-gpio.c
@@ -7,12 +7,14 @@
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
+#include <linux/completion.h>
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c-algo-bit.h>
#include <linux/i2c.h>
#include <linux/init.h>
+#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_data/i2c-gpio.h>
@@ -27,6 +29,9 @@ struct i2c_gpio_private_data {
struct i2c_gpio_platform_data pdata;
#ifdef CONFIG_I2C_GPIO_FAULT_INJECTOR
struct dentry *debug_dir;
+ /* these must be protected by bus lock */
+ struct completion scl_irq_completion;
+ u64 scl_irq_data;
#endif
};
@@ -162,6 +167,70 @@ static int fops_incomplete_write_byte_set(void *data, u64 addr)
}
DEFINE_DEBUGFS_ATTRIBUTE(fops_incomplete_write_byte, NULL, fops_incomplete_write_byte_set, "%llu\n");
+static int i2c_gpio_fi_act_on_scl_irq(struct i2c_gpio_private_data *priv,
+ irqreturn_t handler(int, void*))
+{
+ int ret, irq = gpiod_to_irq(priv->scl);
+
+ if (irq < 0)
+ return irq;
+
+ i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
+
+ ret = gpiod_direction_input(priv->scl);
+ if (ret)
+ goto unlock;
+
+ reinit_completion(&priv->scl_irq_completion);
+
+ ret = request_irq(irq, handler, IRQF_TRIGGER_FALLING,
+ "i2c_gpio_fault_injector_scl_irq", priv);
+ if (ret)
+ goto output;
+
+ wait_for_completion_interruptible(&priv->scl_irq_completion);
+
+ free_irq(irq, priv);
+ output:
+ ret = gpiod_direction_output(priv->scl, 1) ?: ret;
+ unlock:
+ i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
+
+ return ret;
+}
+
+static irqreturn_t lose_arbitration_irq(int irq, void *dev_id)
+{
+ struct i2c_gpio_private_data *priv = dev_id;
+
+ setsda(&priv->bit_data, 0);
+ udelay(priv->scl_irq_data);
+ setsda(&priv->bit_data, 1);
+
+ complete(&priv->scl_irq_completion);
+
+ return IRQ_HANDLED;
+}
+
+static int fops_lose_arbitration_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. Interrupt on falling SDA did only
+ * exercise 'bus busy' detection on some HW but not 'arbitration lost'.
+ * Note that the interrupt latency may cause the first bits to be
+ * transmitted correctly.
+ */
+ return i2c_gpio_fi_act_on_scl_irq(priv, lose_arbitration_irq);
+}
+DEFINE_DEBUGFS_ATTRIBUTE(fops_lose_arbitration, NULL, fops_lose_arbitration_set, "%llu\n");
+
static void i2c_gpio_fault_injector_init(struct platform_device *pdev)
{
struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev);
@@ -181,10 +250,15 @@ static void i2c_gpio_fault_injector_init(struct platform_device *pdev)
if (!priv->debug_dir)
return;
+ init_completion(&priv->scl_irq_completion);
+
debugfs_create_file_unsafe("incomplete_address_phase", 0200, priv->debug_dir,
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)
+ 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
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v2 2/2] i2c: gpio: fault-injector: add 'inject_panic' injector
2019-02-19 16:39 [PATCH v2 0/2] i2c: gpio: fault-injector: add two new injectors Wolfram Sang
2019-02-19 16:39 ` [PATCH v2 1/2] i2c: gpio: fault-injector: add 'lose_arbitration' injector Wolfram Sang
@ 2019-02-19 16:39 ` Wolfram Sang
2019-02-23 9:37 ` Wolfram Sang
1 sibling, 1 reply; 5+ messages in thread
From: Wolfram Sang @ 2019-02-19 16:39 UTC (permalink / raw)
To: linux-i2c; +Cc: linux-renesas-soc, Geert Uytterhoeven, Wolfram Sang
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>
---
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
^ permalink raw reply related [flat|nested] 5+ messages in thread