[PATCH] i2c: aspeed: Fix i2c bus hang in slave read
From: Jian Zhang <hidden>
Date: 2023-08-10 07:22:30
Also in:
linux-arm-kernel, linux-i2c, lkml, openbmc
Subsystem:
arm/aspeed i2c driver, i2c subsystem, i2c subsystem host drivers, the rest · Maintainers:
Ryan Chen, Wolfram Sang, Andi Shyti, Linus Torvalds
When the `CONFIG_I2C_SLAVE` option is enabled and the device operates as a slave, a situation arises where the master sends a START signal without the accompanying STOP signal. This action results in a persistent I2C bus timeout. The core issue stems from the fact that the i2c controller remains in a slave read state without a timeout mechanism. As a consequence, the bus perpetually experiences timeouts. This proposed patch addresses this problem by introducing a status check during i2c transmit timeouts. In the event that the controller is in a slave read state, the i2c controller will be reset to restore proper functionality and allow the I2C bus to resume normal operation. Signed-off-by: Jian Zhang <redacted> --- drivers/i2c/busses/i2c-aspeed.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)
diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
index e76befe3f60f..1a95205fc946 100644
--- a/drivers/i2c/busses/i2c-aspeed.c
+++ b/drivers/i2c/busses/i2c-aspeed.c@@ -113,6 +113,7 @@ ASPEED_I2CD_M_RX_CMD | \ ASPEED_I2CD_M_TX_CMD | \ ASPEED_I2CD_M_START_CMD) +#define ASPEED_I2CD_SLAVE_CMDS_MASK GENMASK(31, 29) /* 0x18 : I2CD Slave Device Address Register */ #define ASPEED_I2CD_DEV_ADDR_MASK GENMASK(6, 0)
@@ -706,6 +707,22 @@ static int aspeed_i2c_master_xfer(struct i2c_adapter *adap, ASPEED_I2CD_BUS_BUSY_STS)) aspeed_i2c_recover_bus(bus); +#if IS_ENABLED(CONFIG_I2C_SLAVE) + /* + * If master timed out and bus is in slave mode. + * reset the slave mode. + */ + if (readl(bus->base + ASPEED_I2C_CMD_REG) & ASPEED_I2CD_SLAVE_CMDS_MASK) { + spin_lock_irqsave(&bus->lock, flags); + u32 func_ctrl_reg_val = readl(bus->base + ASPEED_I2C_FUN_CTRL_REG); + + writel(0, bus->base + ASPEED_I2C_FUN_CTRL_REG); + writel(func_ctrl_reg_val, bus->base + ASPEED_I2C_FUN_CTRL_REG); + bus->slave_state = ASPEED_I2C_SLAVE_INACTIVE; + spin_unlock_irqrestore(&bus->lock, flags); + } +#endif + /* * If timed out and the state is still pending, drop the pending * master command.
--
2.30.2