ppc/pnv: Implement the ChipTOD to Core transfer

One of the functions of the ChipTOD is to transfer TOD to the Core
(aka PC - Pervasive Core) timebase facility.

The ChipTOD can be programmed with a target address to send the TOD
value to. The hardware implementation seems to perform this by
sending the TOD value to a SCOM address.

This implementation grabs the core directly and manipulates the
timebase facility state in the core. This is a hack, but it works
enough for now. A better implementation would implement the transfer
to the PnvCore xscom register and drive the timebase state machine
from there.

Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>

2 files changed, 147 insertions, 0 deletions

diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
index 8beddb1313..0b47b92baa 100644
--- a/hw/ppc/pnv.c
+++ b/hw/ppc/pnv.c
@@ -2121,6 +2121,21 @@ static void pnv_chip_class_init(ObjectClass *klass, void *data)
     dc->desc = "PowerNV Chip";
 }
 
+PnvCore *pnv_chip_find_core(PnvChip *chip, uint32_t core_id)
+{
+    int i;
+
+    for (i = 0; i < chip->nr_cores; i++) {
+        PnvCore *pc = chip->cores[i];
+        CPUCore *cc = CPU_CORE(pc);
+
+        if (cc->core_id == core_id) {
+            return pc;
+        }
+    }
+    return NULL;
+}
+
 PowerPCCPU *pnv_chip_find_cpu(PnvChip *chip, uint32_t pir)
 {
     int i, j;
diff --git a/hw/ppc/pnv_chiptod.c b/hw/ppc/pnv_chiptod.c
index 6ac3eac9d0..3831a72101 100644
--- a/hw/ppc/pnv_chiptod.c
+++ b/hw/ppc/pnv_chiptod.c
@@ -210,6 +210,79 @@ static void chiptod_power10_broadcast_ttype(PnvChipTOD *sender,
     }
 }
 
+static PnvCore *pnv_chip_get_core_by_xscom_base(PnvChip *chip,
+                                                uint32_t xscom_base)
+{
+    PnvChipClass *pcc = PNV_CHIP_GET_CLASS(chip);
+    int i;
+
+    for (i = 0; i < chip->nr_cores; i++) {
+        PnvCore *pc = chip->cores[i];
+        CPUCore *cc = CPU_CORE(pc);
+        int core_hwid = cc->core_id;
+
+        if (pcc->xscom_core_base(chip, core_hwid) == xscom_base) {
+            return pc;
+        }
+    }
+    return NULL;
+}
+
+static PnvCore *chiptod_power9_tx_ttype_target(PnvChipTOD *chiptod,
+                                               uint64_t val)
+{
+    /*
+     * skiboot uses Core ID for P9, though SCOM should work too.
+     */
+    if (val & PPC_BIT(35)) { /* SCOM addressing */
+        uint32_t addr = val >> 32;
+        uint32_t reg = addr & 0xfff;
+
+        if (reg != PC_TOD) {
+            qemu_log_mask(LOG_GUEST_ERROR, "pnv_chiptod: SCOM addressing: "
+                          "unimplemented slave register 0x%" PRIx32 "\n", reg);
+            return NULL;
+        }
+
+        return pnv_chip_get_core_by_xscom_base(chiptod->chip, addr & ~0xfff);
+
+    } else { /* Core ID addressing */
+        uint32_t core_id = GETFIELD(TOD_TX_TTYPE_PIB_SLAVE_ADDR, val) & 0x1f;
+        return pnv_chip_find_core(chiptod->chip, core_id);
+    }
+}
+
+static PnvCore *chiptod_power10_tx_ttype_target(PnvChipTOD *chiptod,
+                                               uint64_t val)
+{
+    /*
+     * skiboot uses SCOM for P10 because Core ID was unable to be made to
+     * work correctly. For this reason only SCOM addressing is implemented.
+     */
+    if (val & PPC_BIT(35)) { /* SCOM addressing */
+        uint32_t addr = val >> 32;
+        uint32_t reg = addr & 0xfff;
+
+        if (reg != PC_TOD) {
+            qemu_log_mask(LOG_GUEST_ERROR, "pnv_chiptod: SCOM addressing: "
+                          "unimplemented slave register 0x%" PRIx32 "\n", reg);
+            return NULL;
+        }
+
+        /*
+         * This may not deal with P10 big-core addressing at the moment.
+         * The big-core code in skiboot syncs small cores, but it targets
+         * the even PIR (first small-core) when syncing second small-core.
+         */
+        return pnv_chip_get_core_by_xscom_base(chiptod->chip, addr & ~0xfff);
+
+    } else { /* Core ID addressing */
+        qemu_log_mask(LOG_UNIMP, "pnv_chiptod: TX TTYPE Core ID "
+                      "addressing is not implemented for POWER10\n");
+        return NULL;
+    }
+}
+
 static void pnv_chiptod_xscom_write(void *opaque, hwaddr addr,
                                     uint64_t val, unsigned size)
 {
@@ -231,6 +304,22 @@ static void pnv_chiptod_xscom_write(void *opaque, hwaddr addr,
         chiptod->pss_mss_ctrl_reg = val & PPC_BITMASK(0, 31);
         break;
 
+    case TOD_TX_TTYPE_CTRL_REG:
+        /*
+         * This register sets the target of the TOD value transfer initiated
+         * by TOD_MOVE_TOD_TO_TB. The TOD is able to send the address to
+         * any target register, though in practice only the PC TOD register
+         * should be used. ChipTOD has a "SCOM addressing" mode which fully
+         * specifies the SCOM address, and a core-ID mode which uses the
+         * core ID to target the PC TOD for a given core.
+         */
+        chiptod->slave_pc_target = pctc->tx_ttype_target(chiptod, val);
+        if (!chiptod->slave_pc_target) {
+            qemu_log_mask(LOG_GUEST_ERROR, "pnv_chiptod: xscom write reg"
+                          " TOD_TX_TTYPE_CTRL_REG val 0x%" PRIx64
+                          " invalid slave address\n", val);
+        }
+        break;
     case TOD_ERROR_REG:
         chiptod->tod_error &= ~val;
         break;
@@ -256,6 +345,47 @@ static void pnv_chiptod_xscom_write(void *opaque, hwaddr addr,
             }
         }
         break;
+
+    case TOD_MOVE_TOD_TO_TB_REG:
+        /*
+         * XXX: it should be a cleaner model to have this drive a SCOM
+         * transaction to the target address, and implement the state machine
+         * in the PnvCore. For now, this hack makes things work.
+         */
+        if (chiptod->tod_state != tod_running) {
+            qemu_log_mask(LOG_GUEST_ERROR, "pnv_chiptod: xscom write reg"
+                          " TOD_MOVE_TOD_TO_TB_REG in bad state %d\n",
+                          chiptod->tod_state);
+        } else if (!(val & PPC_BIT(0))) {
+            qemu_log_mask(LOG_GUEST_ERROR, "pnv_chiptod: xscom write reg"
+                          " TOD_MOVE_TOD_TO_TB_REG with bad val 0x%" PRIx64"\n",
+                          val);
+        } else if (chiptod->slave_pc_target == NULL) {
+            qemu_log_mask(LOG_GUEST_ERROR, "pnv_chiptod: xscom write reg"
+                          " TOD_MOVE_TOD_TO_TB_REG with no slave target\n");
+        } else {
+            PowerPCCPU *cpu = chiptod->slave_pc_target->threads[0];
+            CPUPPCState *env = &cpu->env;
+
+            /*
+             * Moving TOD to TB will set the TB of all threads in a
+             * core, so skiboot only does this once per thread0, so
+             * that is where we keep the timebase state machine.
+             *
+             * It is likely possible for TBST to be driven from other
+             * threads in the core, but for now we only implement it for
+             * thread 0.
+             */
+
+            if (env->pnv_tod_tbst.tb_ready_for_tod) {
+                env->pnv_tod_tbst.tod_sent_to_tb = 1;
+            } else {
+                qemu_log_mask(LOG_GUEST_ERROR, "pnv_chiptod: xscom write reg"
+                              " TOD_MOVE_TOD_TO_TB_REG with TB not ready to"
+                              " receive TOD\n");
+            }
+        }
+        break;
     case TOD_START_TOD_REG:
         if (chiptod->tod_state != tod_stopped) {
             qemu_log_mask(LOG_GUEST_ERROR, "pnv_chiptod: LOAD_TOG_REG in "
@@ -340,6 +470,7 @@ static void pnv_chiptod_power9_class_init(ObjectClass *klass, void *data)
     xdc->dt_xscom = pnv_chiptod_power9_dt_xscom;
 
     pctc->broadcast_ttype = chiptod_power9_broadcast_ttype;
+    pctc->tx_ttype_target = chiptod_power9_tx_ttype_target;
 
     pctc->xscom_size = PNV_XSCOM_CHIPTOD_SIZE;
 }
@@ -375,6 +506,7 @@ static void pnv_chiptod_power10_class_init(ObjectClass *klass, void *data)
     xdc->dt_xscom = pnv_chiptod_power10_dt_xscom;
 
     pctc->broadcast_ttype = chiptod_power10_broadcast_ttype;
+    pctc->tx_ttype_target = chiptod_power10_tx_ttype_target;
 
     pctc->xscom_size = PNV_XSCOM_CHIPTOD_SIZE;
 }