ppc/pnv: Fix PNV I2C invalid status after reset

The PNV I2C Controller was clearing the status register
after a reset without repopulating the "upper threshold
for I2C ports", "Command Complete" and the SCL/SDA input
level fields.

Fixed this for resets caused by a system reset as well
as from writing to the "Immediate Reset" register.

Fixes: 263b81e ("ppc/pnv: Add an I2C controller model")
Signed-off-by: Glenn Miles <milesg@linux.vnet.ibm.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>

hw/ppc/pnv_i2c.c

@@ -463,6 +463,23 @@ static uint64_t pnv_i2c_xscom_read(void *opaque, hwaddr addr,
     return val;
 }
 
+static void pnv_i2c_reset(void *dev)
+{
+    PnvI2C *i2c = PNV_I2C(dev);
+
+    memset(i2c->regs, 0, sizeof(i2c->regs));
+
+    i2c->regs[I2C_STAT_REG] =
+        SETFIELD(I2C_STAT_UPPER_THRS, 0ull, i2c->num_busses - 1) |
+        I2C_STAT_CMD_COMP | I2C_STAT_SCL_INPUT_LEVEL |
+        I2C_STAT_SDA_INPUT_LEVEL;
+    i2c->regs[I2C_EXTD_STAT_REG] =
+        SETFIELD(I2C_EXTD_STAT_FIFO_SIZE, 0ull, PNV_I2C_FIFO_SIZE) |
+        SETFIELD(I2C_EXTD_STAT_I2C_VERSION, 0ull, 23); /* last version */
+
+    fifo8_reset(&i2c->fifo);
+}
+
 static void pnv_i2c_xscom_write(void *opaque, hwaddr addr,
                                 uint64_t val, unsigned size)
 {
@@ -500,16 +517,7 @@ static void pnv_i2c_xscom_write(void *opaque, hwaddr addr,
         break;
 
     case I2C_RESET_I2C_REG:
-        i2c->regs[I2C_MODE_REG] = 0;
-        i2c->regs[I2C_CMD_REG] = 0;
-        i2c->regs[I2C_WATERMARK_REG] = 0;
-        i2c->regs[I2C_INTR_MASK_REG] = 0;
-        i2c->regs[I2C_INTR_COND_REG] = 0;
-        i2c->regs[I2C_INTR_RAW_COND_REG] = 0;
-        i2c->regs[I2C_STAT_REG] = 0;
-        i2c->regs[I2C_RESIDUAL_LEN_REG] = 0;
-        i2c->regs[I2C_EXTD_STAT_REG] &=
-            (I2C_EXTD_STAT_FIFO_SIZE | I2C_EXTD_STAT_I2C_VERSION);
+        pnv_i2c_reset(i2c);
         break;
 
     case I2C_RESET_ERRORS:
@@ -621,20 +629,6 @@ static int pnv_i2c_dt_xscom(PnvXScomInterface *dev, void *fdt,
     return 0;
 }
 
-static void pnv_i2c_reset(void *dev)
-{
-    PnvI2C *i2c = PNV_I2C(dev);
-
-    memset(i2c->regs, 0, sizeof(i2c->regs));
-
-    i2c->regs[I2C_STAT_REG] = I2C_STAT_CMD_COMP;
-    i2c->regs[I2C_EXTD_STAT_REG] =
-        SETFIELD(I2C_EXTD_STAT_FIFO_SIZE, 0ull, PNV_I2C_FIFO_SIZE) |
-        SETFIELD(I2C_EXTD_STAT_I2C_VERSION, 0ull, 23); /* last version */
-
-    fifo8_reset(&i2c->fifo);
-}
-
 static void pnv_i2c_realize(DeviceState *dev, Error **errp)
 {
     PnvI2C *i2c = PNV_I2C(dev);