i2c: have I2C receive operation return uint8_t

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 <cminyard@mvista.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>

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 1a2478b5a9..c6f686c3eb 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)
         }
         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 0a0367ff38..7aa8727771 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 463fafe3c5..6e4d542f51 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 cffbf586d4..1fc7b86f19 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 f6d7163273..0c32f6f8b6 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 eeb11000f0..ce6d40ac9c 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 51ec355f3f..c83d803dd8 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 cf4c45a98f..8e236f7bb4 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.
      */
-    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);