QEMU complains about access to unimplemented register when Linux
inits the controller. It is the SMBUS interrupt mask which the
driver unmasks. Since the model implements no SMBUS interrupts,
the mask can be implemented trivially.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 hw/i2c/designware_i2c.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/hw/i2c/designware_i2c.c b/hw/i2c/designware_i2c.c
index b7be4d68c4..cc37bde2ae 100644
--- a/hw/i2c/designware_i2c.c
+++ b/hw/i2c/designware_i2c.c
@@ -142,6 +142,7 @@ REG32(DW_IC_ENABLE_STATUS,      0x9c) /* I2C enable status */
     FIELD(DW_IC_ENABLE_STATUS, IC_EN,                   0, 1)
 REG32(DW_IC_FS_SPKLEN,          0xa0) /* I2C SS, FS or FM+ spike suppression limit */
 REG32(DW_IC_CLR_RESTART_DET,    0xa8)
+REG32(DW_IC_SMBUS_INTR_MASK,    0xcc) /* SMBus Interrupt Mask */
 REG32(DW_IC_COMP_PARAM_1,       0xf4) /* Component parameter */
     FIELD(DW_IC_COMP_PARAM_1, TX_FIFO_SIZE,       16, 8)
     FIELD(DW_IC_COMP_PARAM_1, RX_FIFO_SIZE,        8, 8)
@@ -610,6 +611,10 @@ static const RegisterAccessInfo designware_i2c_regs_info[] = {
     },{ .name  = "DW_IC_CLR_RESTART_DET", .addr = A_DW_IC_CLR_RESTART_DET,
         .ro    = 0xffffffff,
         .post_read = dw_ic_clr_intr_reg_post_read,
+    },{ .name  = "DW_IC_SMBUS_INTR_MASK", .addr = A_DW_IC_SMBUS_INTR_MASK,
+        /* No SMBus interrupts are implemented, Linux updates the mask */
+        .reset =      0x7ff,
+        .unimp = 0xfffff800,
     },{ .name  = "DW_IC_COMP_PARAM_1", .addr = A_DW_IC_COMP_PARAM_1,
         .reset = /* HAS_DMA and HC_COUNT_VAL are disabled */
             ((2 << R_DW_IC_COMP_PARAM_1_APB_DATA_WIDTH_32_SHIFT) |
-- 
2.53.0

On 7/5/26 14:05, Nicholas Piggin wrote:
> QEMU complains about access to unimplemented register when Linux
> inits the controller. It is the SMBUS interrupt mask which the
> driver unmasks. Since the model implements no SMBUS interrupts,
> the mask can be implemented trivially.
> 
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
>   hw/i2c/designware_i2c.c | 5 +++++
>   1 file changed, 5 insertions(+)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>