diff mbox series

[PULL,18/72] ppc/pnv: raise no-response errors if an LPC transaction fails

Message ID 20250311125815.903177-19-npiggin@gmail.com (mailing list archive)
State New
Headers show
Series [PULL,01/72] ppc/ppc405: Remove tests | expand

Commit Message

Nicholas Piggin March 11, 2025, 12:57 p.m. UTC 
If nothing responds to an LPC access, the LPC host controller should
set an IRQSTAT error. Model this behaviour.

skiboot uses this error to "probe" LPC accesses, among other things to
determine if a SuperIO chip is present. After this change it recognizes
there is no SuperIO present and does not keep trying to access it.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 hw/ppc/pnv_lpc.c | 10 ++++++++++
 1 file changed, 10 insertions(+)
diff mbox series

Patch

diff --git a/hw/ppc/pnv_lpc.c b/hw/ppc/pnv_lpc.c
index d0fccc165d..0e02ce6e94 100644
--- a/hw/ppc/pnv_lpc.c
+++ b/hw/ppc/pnv_lpc.c
@@ -353,6 +353,8 @@  static const MemoryRegionOps pnv_lpc_xscom_ops = {
     .endianness = DEVICE_BIG_ENDIAN,
 };
 
+static void pnv_lpc_opb_noresponse(PnvLpcController *lpc);
+
 static uint64_t pnv_lpc_mmio_read(void *opaque, hwaddr addr, unsigned size)
 {
     PnvLpcController *lpc = PNV_LPC(opaque);
@@ -376,6 +378,7 @@  static uint64_t pnv_lpc_mmio_read(void *opaque, hwaddr addr, unsigned size)
     }
 
     if (result != MEMTX_OK) {
+        pnv_lpc_opb_noresponse(lpc);
         qemu_log_mask(LOG_GUEST_ERROR, "OPB read failed at @0x%"
                       HWADDR_PRIx "\n", addr);
     }
@@ -406,6 +409,7 @@  static void pnv_lpc_mmio_write(void *opaque, hwaddr addr,
     }
 
     if (result != MEMTX_OK) {
+        pnv_lpc_opb_noresponse(lpc);
         qemu_log_mask(LOG_GUEST_ERROR, "OPB write failed at @0x%"
                       HWADDR_PRIx "\n", addr);
     }
@@ -511,6 +515,12 @@  static void pnv_lpc_eval_irqs(PnvLpcController *lpc)
     qemu_set_irq(lpc->psi_irq_lpchc, lpc->opb_irq_stat != 0);
 }
 
+static void pnv_lpc_opb_noresponse(PnvLpcController *lpc)
+{
+    lpc->lpc_hc_irqstat |= LPC_HC_IRQ_SYNC_NORESP_ERR;
+    pnv_lpc_eval_irqs(lpc);
+}
+
 static uint64_t lpc_hc_read(void *opaque, hwaddr addr, unsigned size)
 {
     PnvLpcController *lpc = opaque;