From cc083d8a25e0a886c3cd4bea0bf57ac4e896fa3f Mon Sep 17 00:00:00 2001 From: Corey Minyard Date: Mon, 24 Oct 2016 10:42:33 -0500 Subject: i2c: Add asserts for second smbus i2c_start_transfer() Some SMBus operations restart the transfer to convert from write to read mode without an intervening i2c_end_transfer(). The second call cannot fail, so the return code is unchecked, but this causes Coverity to complain. So add some asserts and documentation about this. Signed-off-by: Corey Minyard Reviewed-by: Peter Maydell Signed-off-by: Peter Maydell --- hw/i2c/core.c | 7 ++++++- hw/i2c/smbus.c | 12 +++++++++--- 2 files changed, 15 insertions(+), 4 deletions(-) diff --git a/hw/i2c/core.c b/hw/i2c/core.c index bd8f16759d..abd4c4cddb 100644 --- a/hw/i2c/core.c +++ b/hw/i2c/core.c @@ -88,7 +88,12 @@ int i2c_bus_busy(I2CBus *bus) return !QLIST_EMPTY(&bus->current_devs); } -/* Returns non-zero if the address is not valid. */ +/* + * Returns non-zero if the address is not valid. If this is called + * again without an intervening i2c_end_transfer(), like in the SMBus + * case where the operation is switched from write to read, this + * function will not rescan the bus and thus cannot fail. + */ /* TODO: Make this handle multiple masters. */ int i2c_start_transfer(I2CBus *bus, uint8_t address, int recv) { diff --git a/hw/i2c/smbus.c b/hw/i2c/smbus.c index 3979b3dad7..5b4dd3eba4 100644 --- a/hw/i2c/smbus.c +++ b/hw/i2c/smbus.c @@ -248,7 +248,9 @@ int smbus_read_byte(I2CBus *bus, uint8_t addr, uint8_t command) return -1; } i2c_send(bus, command); - i2c_start_transfer(bus, addr, 1); + if (i2c_start_transfer(bus, addr, 1)) { + assert(0); + } data = i2c_recv(bus); i2c_nack(bus); i2c_end_transfer(bus); @@ -273,7 +275,9 @@ int smbus_read_word(I2CBus *bus, uint8_t addr, uint8_t command) return -1; } i2c_send(bus, command); - i2c_start_transfer(bus, addr, 1); + if (i2c_start_transfer(bus, addr, 1)) { + assert(0); + } data = i2c_recv(bus); data |= i2c_recv(bus) << 8; i2c_nack(bus); @@ -302,7 +306,9 @@ int smbus_read_block(I2CBus *bus, uint8_t addr, uint8_t command, uint8_t *data) return -1; } i2c_send(bus, command); - i2c_start_transfer(bus, addr, 1); + if (i2c_start_transfer(bus, addr, 1)) { + assert(0); + } len = i2c_recv(bus); if (len > 32) { len = 0; -- cgit v1.2.3