Re: [Qemu-devel] [PATCH v3 02/16] i2c: have I2C receive operation return uint8_t

[Philippe Mathieu-Daudé]

Hi Corey,

On 26/11/18 21:04, address@hidden wrote:
> From: Corey Minyard <address@hidden>
> 
> It is never supposed to fail and cannot return an error, so just
> have it return the proper type.  Have it return 0xff on nothing
> available, since that's what would happen on a real bus.
> 
> Signed-off-by: Corey Minyard <address@hidden>
> Reviewed-by: Peter Maydell <address@hidden>
> ---
>  hw/arm/pxa2xx.c         |  2 +-
>  hw/arm/tosa.c           |  4 ++--
>  hw/arm/z2.c             |  2 +-
>  hw/audio/wm8750.c       |  2 +-
>  hw/display/sii9022.c    |  2 +-
>  hw/display/ssd0303.c    |  4 ++--
>  hw/gpio/max7310.c       |  2 +-
>  hw/i2c/core.c           | 32 +++++++++++++-------------------
>  hw/i2c/i2c-ddc.c        |  2 +-
>  hw/i2c/smbus_slave.c    |  4 ++--
>  hw/input/lm832x.c       |  2 +-
>  hw/misc/pca9552.c       |  2 +-
>  hw/misc/tmp105.c        |  2 +-
>  hw/misc/tmp421.c        |  2 +-
>  hw/nvram/eeprom_at24c.c |  4 ++--
>  hw/timer/ds1338.c       |  2 +-
>  hw/timer/m41t80.c       |  2 +-
>  hw/timer/twl92230.c     |  2 +-
>  include/hw/i2c/i2c.h    |  7 +++----
>  19 files changed, 37 insertions(+), 44 deletions(-)
> 
> diff --git a/hw/arm/pxa2xx.c b/hw/arm/pxa2xx.c
> index f598a1c053..3d7c88910e 100644
> --- a/hw/arm/pxa2xx.c
> +++ b/hw/arm/pxa2xx.c
> @@ -1286,7 +1286,7 @@ static int pxa2xx_i2c_event(I2CSlave *i2c, enum 
> i2c_event event)
>      return 0;
>  }
>  
> -static int pxa2xx_i2c_rx(I2CSlave *i2c)
> +static uint8_t pxa2xx_i2c_rx(I2CSlave *i2c)
>  {
>      PXA2xxI2CSlaveState *slave = PXA2XX_I2C_SLAVE(i2c);
>      PXA2xxI2CState *s = slave->host;
> diff --git a/hw/arm/tosa.c b/hw/arm/tosa.c
> index 7a925fa5e6..eef9d427e7 100644
> --- a/hw/arm/tosa.c
> +++ b/hw/arm/tosa.c
> @@ -197,10 +197,10 @@ static int tosa_dac_event(I2CSlave *i2c, enum i2c_event 
> event)
>      return 0;
>  }
>  
> -static int tosa_dac_recv(I2CSlave *s)
> +static uint8_t tosa_dac_recv(I2CSlave *s)
>  {
>      printf("%s: recv not supported!!!\n", __func__);
> -    return -1;
> +    return 0xff;
>  }
>  
>  static void tosa_tg_init(PXA2xxState *cpu)
> diff --git a/hw/arm/z2.c b/hw/arm/z2.c
> index 697a822f1e..6f18d924df 100644
> --- a/hw/arm/z2.c
> +++ b/hw/arm/z2.c
> @@ -243,7 +243,7 @@ static int aer915_event(I2CSlave *i2c, enum i2c_event 
> event)
>      return 0;
>  }
>  
> -static int aer915_recv(I2CSlave *slave)
> +static uint8_t aer915_recv(I2CSlave *slave)
>  {
>      AER915State *s = AER915(slave);
>      int retval = 0x00;
> diff --git a/hw/audio/wm8750.c b/hw/audio/wm8750.c
> index f4aa838f62..169b006ade 100644
> --- a/hw/audio/wm8750.c
> +++ b/hw/audio/wm8750.c
> @@ -561,7 +561,7 @@ static int wm8750_tx(I2CSlave *i2c, uint8_t data)
>      return 0;
>  }
>  
> -static int wm8750_rx(I2CSlave *i2c)
> +static uint8_t wm8750_rx(I2CSlave *i2c)
>  {
>      return 0x00;
>  }
> diff --git a/hw/display/sii9022.c b/hw/display/sii9022.c
> index eaf11a6e7b..9994385c35 100644
> --- a/hw/display/sii9022.c
> +++ b/hw/display/sii9022.c
> @@ -79,7 +79,7 @@ static int sii9022_event(I2CSlave *i2c, enum i2c_event 
> event)
>      return 0;
>  }
>  
> -static int sii9022_rx(I2CSlave *i2c)
> +static uint8_t sii9022_rx(I2CSlave *i2c)
>  {
>      sii9022_state *s = SII9022(i2c);
>      uint8_t res = 0x00;
> diff --git a/hw/display/ssd0303.c b/hw/display/ssd0303.c
> index eb90ba26be..8edf34986c 100644
> --- a/hw/display/ssd0303.c
> +++ b/hw/display/ssd0303.c
> @@ -62,10 +62,10 @@ typedef struct {
>      uint8_t framebuffer[132*8];
>  } ssd0303_state;
>  
> -static int ssd0303_recv(I2CSlave *i2c)
> +static uint8_t ssd0303_recv(I2CSlave *i2c)
>  {
>      BADF("Reads not implemented\n");
> -    return -1;
> +    return 0xff;
>  }
>  
>  static int ssd0303_send(I2CSlave *i2c, uint8_t data)
> diff --git a/hw/gpio/max7310.c b/hw/gpio/max7310.c
> index a560e3afd2..f35a930276 100644
> --- a/hw/gpio/max7310.c
> +++ b/hw/gpio/max7310.c
> @@ -39,7 +39,7 @@ static void max7310_reset(DeviceState *dev)
>      s->command = 0x00;
>  }
>  
> -static int max7310_rx(I2CSlave *i2c)
> +static uint8_t max7310_rx(I2CSlave *i2c)
>  {
>      MAX7310State *s = MAX7310(i2c);
>  
> diff --git a/hw/i2c/core.c b/hw/i2c/core.c
> index b54725985a..15237ad073 100644
> --- a/hw/i2c/core.c
> +++ b/hw/i2c/core.c
> @@ -191,23 +191,17 @@ int i2c_send_recv(I2CBus *bus, uint8_t *data, bool send)

i2c_send_recv() could benefit the same improvement.

>          }
>          return ret ? -1 : 0;
>      } else {
> -        if ((QLIST_EMPTY(&bus->current_devs)) || (bus->broadcast)) {
> -            return -1;
> -        }
> -
> -        sc = I2C_SLAVE_GET_CLASS(QLIST_FIRST(&bus->current_devs)->elt);
> -        if (sc->recv) {
> -            s = QLIST_FIRST(&bus->current_devs)->elt;
> -            ret = sc->recv(s);
> -            trace_i2c_recv(s->address, ret);
> -            if (ret < 0) {
> -                return ret;
> -            } else {
> -                *data = ret;
> -                return 0;
> +        ret = 0xff;
> +        if (!QLIST_EMPTY(&bus->current_devs) && !bus->broadcast) {
> +            sc = I2C_SLAVE_GET_CLASS(QLIST_FIRST(&bus->current_devs)->elt);
> +            if (sc->recv) {
> +                s = QLIST_FIRST(&bus->current_devs)->elt;
> +                ret = sc->recv(s);
> +                trace_i2c_recv(s->address, ret);
>              }
>          }
> -        return -1;
> +        *data = ret;
> +        return 0;
>      }
>  }
>  
> @@ -216,12 +210,12 @@ int i2c_send(I2CBus *bus, uint8_t data)
>      return i2c_send_recv(bus, &data, true);
>  }
>  
> -int i2c_recv(I2CBus *bus)
> +uint8_t i2c_recv(I2CBus *bus)
>  {
> -    uint8_t data;
> -    int ret = i2c_send_recv(bus, &data, false);
> +    uint8_t data = 0xff;
>  
> -    return ret < 0 ? ret : data;
> +    i2c_send_recv(bus, &data, false);
> +    return data;
>  }
>  
>  void i2c_nack(I2CBus *bus)
> diff --git a/hw/i2c/i2c-ddc.c b/hw/i2c/i2c-ddc.c
> index be34fe072c..95325358db 100644
> --- a/hw/i2c/i2c-ddc.c
> +++ b/hw/i2c/i2c-ddc.c
> @@ -51,7 +51,7 @@ static int i2c_ddc_event(I2CSlave *i2c, enum i2c_event 
> event)
>      return 0;
>  }
>  
> -static int i2c_ddc_rx(I2CSlave *i2c)
> +static uint8_t i2c_ddc_rx(I2CSlave *i2c)
>  {
>      I2CDDCState *s = I2CDDC(i2c);
>  
> diff --git a/hw/i2c/smbus_slave.c b/hw/i2c/smbus_slave.c
> index 1e734752d7..549e7ae933 100644
> --- a/hw/i2c/smbus_slave.c
> +++ b/hw/i2c/smbus_slave.c
> @@ -156,11 +156,11 @@ static int smbus_i2c_event(I2CSlave *s, enum i2c_event 
> event)
>      return 0;
>  }
>  
> -static int smbus_i2c_recv(I2CSlave *s)
> +static uint8_t smbus_i2c_recv(I2CSlave *s)
>  {
>      SMBusDevice *dev = SMBUS_DEVICE(s);
>      SMBusDeviceClass *sc = SMBUS_DEVICE_GET_CLASS(dev);
> -    int ret;
> +    uint8_t ret;
>  
>      switch (dev->mode) {
>      case SMBUS_RECV_BYTE:
> diff --git a/hw/input/lm832x.c b/hw/input/lm832x.c
> index 74da30d9ca..9ae037953d 100644
> --- a/hw/input/lm832x.c
> +++ b/hw/input/lm832x.c
> @@ -401,7 +401,7 @@ static int lm_i2c_event(I2CSlave *i2c, enum i2c_event 
> event)
>      return 0;
>  }
>  
> -static int lm_i2c_rx(I2CSlave *i2c)
> +static uint8_t lm_i2c_rx(I2CSlave *i2c)
>  {
>      LM823KbdState *s = LM8323(i2c);
>  
> diff --git a/hw/misc/pca9552.c b/hw/misc/pca9552.c
> index 9775d5274a..7325d3f287 100644
> --- a/hw/misc/pca9552.c
> +++ b/hw/misc/pca9552.c
> @@ -115,7 +115,7 @@ static void pca9552_autoinc(PCA9552State *s)
>      }
>  }
>  
> -static int pca9552_recv(I2CSlave *i2c)
> +static uint8_t pca9552_recv(I2CSlave *i2c)
>  {
>      PCA9552State *s = PCA9552(i2c);
>      uint8_t ret;
> diff --git a/hw/misc/tmp105.c b/hw/misc/tmp105.c
> index 0918f3a6ea..a4cae665b7 100644
> --- a/hw/misc/tmp105.c
> +++ b/hw/misc/tmp105.c
> @@ -147,7 +147,7 @@ static void tmp105_write(TMP105State *s)
>      }
>  }
>  
> -static int tmp105_rx(I2CSlave *i2c)
> +static uint8_t tmp105_rx(I2CSlave *i2c)
>  {
>      TMP105State *s = TMP105(i2c);
>  
> diff --git a/hw/misc/tmp421.c b/hw/misc/tmp421.c
> index c234044305..a75eb994a8 100644
> --- a/hw/misc/tmp421.c
> +++ b/hw/misc/tmp421.c
> @@ -249,7 +249,7 @@ static void tmp421_write(TMP421State *s)
>      }
>  }
>  
> -static int tmp421_rx(I2CSlave *i2c)
> +static uint8_t tmp421_rx(I2CSlave *i2c)
>  {
>      TMP421State *s = TMP421(i2c);
>  
> diff --git a/hw/nvram/eeprom_at24c.c b/hw/nvram/eeprom_at24c.c
> index 27cd01e615..d1456dafbd 100644
> --- a/hw/nvram/eeprom_at24c.c
> +++ b/hw/nvram/eeprom_at24c.c
> @@ -74,10 +74,10 @@ int at24c_eeprom_event(I2CSlave *s, enum i2c_event event)
>  }
>  
>  static
> -int at24c_eeprom_recv(I2CSlave *s)
> +uint8_t at24c_eeprom_recv(I2CSlave *s)
>  {
>      EEPROMState *ee = AT24C_EE(s);
> -    int ret;
> +    uint8_t ret;
>  
>      ret = ee->mem[ee->cur];
>  
> diff --git a/hw/timer/ds1338.c b/hw/timer/ds1338.c
> index 3849b74a68..03da75486b 100644
> --- a/hw/timer/ds1338.c
> +++ b/hw/timer/ds1338.c
> @@ -117,7 +117,7 @@ static int ds1338_event(I2CSlave *i2c, enum i2c_event 
> event)
>      return 0;
>  }
>  
> -static int ds1338_recv(I2CSlave *i2c)
> +static uint8_t ds1338_recv(I2CSlave *i2c)
>  {
>      DS1338State *s = DS1338(i2c);
>      uint8_t res;
> diff --git a/hw/timer/m41t80.c b/hw/timer/m41t80.c
> index 734d7d95fc..c45b9297d8 100644
> --- a/hw/timer/m41t80.c
> +++ b/hw/timer/m41t80.c
> @@ -40,7 +40,7 @@ static int m41t80_send(I2CSlave *i2c, uint8_t data)
>      return 0;
>  }
>  
> -static int m41t80_recv(I2CSlave *i2c)
> +static uint8_t m41t80_recv(I2CSlave *i2c)
>  {
>      M41t80State *s = M41T80(i2c);
>      struct tm now;
> diff --git a/hw/timer/twl92230.c b/hw/timer/twl92230.c
> index 3b43b46199..659b216dca 100644
> --- a/hw/timer/twl92230.c
> +++ b/hw/timer/twl92230.c
> @@ -737,7 +737,7 @@ static int menelaus_tx(I2CSlave *i2c, uint8_t data)
>      return 0;
>  }
>  
> -static int menelaus_rx(I2CSlave *i2c)
> +static uint8_t menelaus_rx(I2CSlave *i2c)
>  {
>      MenelausState *s = TWL92230(i2c);
>  
> diff --git a/include/hw/i2c/i2c.h b/include/hw/i2c/i2c.h
> index 5dc166158b..75c5bd638b 100644
> --- a/include/hw/i2c/i2c.h
> +++ b/include/hw/i2c/i2c.h
> @@ -33,10 +33,9 @@ typedef struct I2CSlaveClass {
>  
>      /*
>       * Slave to master.  This cannot fail, the device should always
> -     * return something here.  Negative values probably result in 0xff
> -     * and a possible log from the driver, and shouldn't be used.
> +     * return something here.

Maybe use simple comment as "Master receives the data sent by the Slave"

>       */
> -    int (*recv)(I2CSlave *s);
> +    uint8_t (*recv)(I2CSlave *s);
>  
>      /*
>       * Notify the slave of a bus state change.  For start event,
> @@ -78,7 +77,7 @@ void i2c_end_transfer(I2CBus *bus);
>  void i2c_nack(I2CBus *bus);
>  int i2c_send_recv(I2CBus *bus, uint8_t *data, bool send);
>  int i2c_send(I2CBus *bus, uint8_t data);
> -int i2c_recv(I2CBus *bus);
> +uint8_t i2c_recv(I2CBus *bus);
>  
>  DeviceState *i2c_create_slave(I2CBus *bus, const char *name, uint8_t addr);
>  

Reviewed-by: Philippe Mathieu-Daudé <address@hidden>
Tested-by: Philippe Mathieu-Daudé <address@hidden>