It only support continuous pool buffer memory region for all I2C bus.
However, the pool buffer address of all I2c bus are discontinuous
for AST2700.

Ex: the pool buffer address of I2C bus for ast2700 as following.
0x1A0 - 0x1BF: Device 0 buffer
0x2A0 - 0x2BF: Device 1 buffer
0x3A0 - 0x3BF: Device 2 buffer
0x4A0 - 0x4BF: Device 3 buffer
0x5A0 - 0x5BF: Device 4 buffer
0x6A0 - 0x6BF: Device 5 buffer
0x7A0 - 0x7BF: Device 6 buffer
0x8A0 - 0x8BF: Device 7 buffer
0x9A0 - 0x9BF: Device 8 buffer
0xAA0 - 0xABF: Device 9 buffer
0xBA0 - 0xBBF: Device 10 buffer
0xCA0 - 0xCBF: Device 11 buffer
0xDA0 - 0xDBF: Device 12 buffer
0xEA0 - 0xEBF: Device 13 buffer
0xFA0 – 0xFBF: Device 14 buffer
0x10A0 – 0x10BF: Device 15 buffer

Introduce a new class attribute to make user set each I2C bus
pool buffer gap size. Update formula to create all I2C bus
pool buffer memory regions.

Signed-off-by: Jamin Lin <jamin_lin@aspeedtech.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
---
 hw/i2c/aspeed_i2c.c         | 3 ++-
 include/hw/i2c/aspeed_i2c.h | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/hw/i2c/aspeed_i2c.c b/hw/i2c/aspeed_i2c.c
index d3d49340ea..abcb1d5330 100644
--- a/hw/i2c/aspeed_i2c.c
+++ b/hw/i2c/aspeed_i2c.c
@@ -1098,6 +1098,7 @@ static void aspeed_i2c_realize(DeviceState *dev, Error **errp)
     AspeedI2CState *s = ASPEED_I2C(dev);
     AspeedI2CClass *aic = ASPEED_I2C_GET_CLASS(s);
     uint32_t reg_offset = aic->reg_size + aic->reg_gap_size;
+    uint32_t pool_offset = aic->pool_size + aic->pool_gap_size;
 
     sysbus_init_irq(sbd, &s->irq);
     memory_region_init_io(&s->iomem, OBJECT(s), &aspeed_i2c_ctrl_ops, s,
@@ -1133,7 +1134,7 @@ static void aspeed_i2c_realize(DeviceState *dev, Error **errp)
     } else {
         for (i = 0; i < aic->num_busses; i++) {
             memory_region_add_subregion(&s->iomem,
-                                        aic->pool_base + (aic->pool_size * i),
+                                        aic->pool_base + (pool_offset * i),
                                         &s->busses[i].mr_pool);
         }
     }
diff --git a/include/hw/i2c/aspeed_i2c.h b/include/hw/i2c/aspeed_i2c.h
index 8e62ec64f8..b42c4dc584 100644
--- a/include/hw/i2c/aspeed_i2c.h
+++ b/include/hw/i2c/aspeed_i2c.h
@@ -284,6 +284,7 @@ struct AspeedI2CClass {
 
     uint64_t pool_size;
     hwaddr pool_base;
+    uint32_t pool_gap_size;
     uint8_t *(*bus_pool_base)(AspeedI2CBus *);
     bool check_sram;
     bool has_dma;
-- 
2.34.1