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author | Wolfram Sang <wsa+renesas@sang-engineering.com> | 2019-02-19 17:39:45 +0100 |
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committer | Wolfram Sang <wsa@the-dreams.de> | 2019-02-23 10:33:51 +0100 |
commit | 63e57b6f191db99ffdd0dc6c7b9ee6b2cf7abb04 (patch) | |
tree | 9a2544d399233f0e601dd5a0b7260be0aa8a9089 /drivers/i2c | |
parent | i2c: tegra: remove multi-master support (diff) | |
download | linux-63e57b6f191db99ffdd0dc6c7b9ee6b2cf7abb04.tar.xz linux-63e57b6f191db99ffdd0dc6c7b9ee6b2cf7abb04.zip |
i2c: gpio: fault-injector: add 'lose_arbitration' injector
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>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c')
-rw-r--r-- | drivers/i2c/busses/i2c-gpio.c | 74 |
1 files changed, 74 insertions, 0 deletions
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); } |