[PULL,15/96] ppc/pnv: Implement POWER9 LPC PSI serirq outputs and auto-clear function

The POWER8 LPC ISA device irqs all get combined and reported to the line
connected the PSI LPCHC irq. POWER9 changed this so only internal LPC
host controller irqs use that line, and the device irqs get routed to
4 new lines connected to PSI SERIRQ0-3.

POWER9 also introduced a new feature that automatically clears the irq
status in the LPC host controller when EOI'ed, so software does not have
to.

The powernv OPAL (skiboot) firmware managed to work because the LPCHC
irq handler scanned all LPC irqs and handled those including clearing
status even on POWER9 systems. So LPC irqs worked despite OPAL thinking
it was running in POWER9 mode. After this change, UART interrupts show
up on serirq1 which is where OPAL routes them to:

 cat /proc/interrupts
 ...
 20:          0  XIVE-IRQ 1048563 Level     opal-psi#0:lpchc
 ...
 25:         34  XIVE-IRQ 1048568 Level     opal-psi#0:lpc_serirq_mux1

Whereas they previously turn up on lpchc.

Reviewed-by: Glenn Miles <milesg@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 hw/ppc/pnv.c             |  36 +++++++++--
 hw/ppc/pnv_lpc.c         | 128 ++++++++++++++++++++++++++++++++-------
 include/hw/ppc/pnv_lpc.h |  14 ++++-
 3 files changed, 148 insertions(+), 30 deletions(-)

On 7/26/24 01:52, Nicholas Piggin wrote:
> The POWER8 LPC ISA device irqs all get combined and reported to the line
> connected the PSI LPCHC irq. POWER9 changed this so only internal LPC
> host controller irqs use that line, and the device irqs get routed to
> 4 new lines connected to PSI SERIRQ0-3.
> 
> POWER9 also introduced a new feature that automatically clears the irq
> status in the LPC host controller when EOI'ed, so software does not have
> to.
> 
> The powernv OPAL (skiboot) firmware managed to work because the LPCHC
> irq handler scanned all LPC irqs and handled those including clearing
> status even on POWER9 systems. So LPC irqs worked despite OPAL thinking
> it was running in POWER9 mode. After this change, UART interrupts show
> up on serirq1 which is where OPAL routes them to:
> 
>   cat /proc/interrupts
>   ...
>   20:          0  XIVE-IRQ 1048563 Level     opal-psi#0:lpchc
>   ...
>   25:         34  XIVE-IRQ 1048568 Level     opal-psi#0:lpc_serirq_mux1
> 
> Whereas they previously turn up on lpchc.
> 
> Reviewed-by: Glenn Miles <milesg@linux.ibm.com>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
>   hw/ppc/pnv.c             |  36 +++++++++--
>   hw/ppc/pnv_lpc.c         | 128 ++++++++++++++++++++++++++++++++-------
>   include/hw/ppc/pnv_lpc.h |  14 ++++-
>   3 files changed, 148 insertions(+), 30 deletions(-)
> 
> diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
> index 13cebd6ab9..f56dcf6597 100644
> --- a/hw/ppc/pnv.c
> +++ b/hw/ppc/pnv.c
> @@ -727,7 +727,8 @@ static ISABus *pnv_chip_power8_isa_create(PnvChip *chip, Error **errp)
>       Pnv8Chip *chip8 = PNV8_CHIP(chip);
>       qemu_irq irq = qdev_get_gpio_in(DEVICE(&chip8->psi), PSIHB_IRQ_EXTERNAL);
>   
> -    qdev_connect_gpio_out(DEVICE(&chip8->lpc), 0, irq);
> +    qdev_connect_gpio_out_named(DEVICE(&chip8->lpc), "LPCHC", 0, irq);
> +
>       return pnv_lpc_isa_create(&chip8->lpc, true, errp);
>   }
>   
> @@ -736,25 +737,48 @@ static ISABus *pnv_chip_power8nvl_isa_create(PnvChip *chip, Error **errp)
>       Pnv8Chip *chip8 = PNV8_CHIP(chip);
>       qemu_irq irq = qdev_get_gpio_in(DEVICE(&chip8->psi), PSIHB_IRQ_LPC_I2C);
>   
> -    qdev_connect_gpio_out(DEVICE(&chip8->lpc), 0, irq);
> +    qdev_connect_gpio_out_named(DEVICE(&chip8->lpc), "LPCHC", 0, irq);
> +
>       return pnv_lpc_isa_create(&chip8->lpc, false, errp);
>   }
>   
>   static ISABus *pnv_chip_power9_isa_create(PnvChip *chip, Error **errp)
>   {
>       Pnv9Chip *chip9 = PNV9_CHIP(chip);
> -    qemu_irq irq = qdev_get_gpio_in(DEVICE(&chip9->psi), PSIHB9_IRQ_LPCHC);
> +    qemu_irq irq;
> +
> +    irq = qdev_get_gpio_in(DEVICE(&chip9->psi), PSIHB9_IRQ_LPCHC);
> +    qdev_connect_gpio_out_named(DEVICE(&chip9->lpc), "LPCHC", 0, irq);
> +
> +    irq = qdev_get_gpio_in(DEVICE(&chip9->psi), PSIHB9_IRQ_LPC_SIRQ0);
> +    qdev_connect_gpio_out_named(DEVICE(&chip9->lpc), "SERIRQ", 0, irq);
> +    irq = qdev_get_gpio_in(DEVICE(&chip9->psi), PSIHB9_IRQ_LPC_SIRQ1);
> +    qdev_connect_gpio_out_named(DEVICE(&chip9->lpc), "SERIRQ", 1, irq);
> +    irq = qdev_get_gpio_in(DEVICE(&chip9->psi), PSIHB9_IRQ_LPC_SIRQ2);
> +    qdev_connect_gpio_out_named(DEVICE(&chip9->lpc), "SERIRQ", 2, irq);
> +    irq = qdev_get_gpio_in(DEVICE(&chip9->psi), PSIHB9_IRQ_LPC_SIRQ3);
> +    qdev_connect_gpio_out_named(DEVICE(&chip9->lpc), "SERIRQ", 3, irq);
>   
> -    qdev_connect_gpio_out(DEVICE(&chip9->lpc), 0, irq);
>       return pnv_lpc_isa_create(&chip9->lpc, false, errp);
>   }
>   
>   static ISABus *pnv_chip_power10_isa_create(PnvChip *chip, Error **errp)
>   {
>       Pnv10Chip *chip10 = PNV10_CHIP(chip);
> -    qemu_irq irq = qdev_get_gpio_in(DEVICE(&chip10->psi), PSIHB9_IRQ_LPCHC);
> +    qemu_irq irq;
> +
> +    irq = qdev_get_gpio_in(DEVICE(&chip10->psi), PSIHB9_IRQ_LPCHC);
> +    qdev_connect_gpio_out_named(DEVICE(&chip10->lpc), "LPCHC", 0, irq);
> +
> +    irq = qdev_get_gpio_in(DEVICE(&chip10->psi), PSIHB9_IRQ_LPC_SIRQ0);
> +    qdev_connect_gpio_out_named(DEVICE(&chip10->lpc), "SERIRQ", 0, irq);
> +    irq = qdev_get_gpio_in(DEVICE(&chip10->psi), PSIHB9_IRQ_LPC_SIRQ1);
> +    qdev_connect_gpio_out_named(DEVICE(&chip10->lpc), "SERIRQ", 1, irq);
> +    irq = qdev_get_gpio_in(DEVICE(&chip10->psi), PSIHB9_IRQ_LPC_SIRQ2);
> +    qdev_connect_gpio_out_named(DEVICE(&chip10->lpc), "SERIRQ", 2, irq);
> +    irq = qdev_get_gpio_in(DEVICE(&chip10->psi), PSIHB9_IRQ_LPC_SIRQ3);
> +    qdev_connect_gpio_out_named(DEVICE(&chip10->lpc), "SERIRQ", 3, irq);
>   
> -    qdev_connect_gpio_out(DEVICE(&chip10->lpc), 0, irq);
>       return pnv_lpc_isa_create(&chip10->lpc, false, errp);
>   }
>   
> diff --git a/hw/ppc/pnv_lpc.c b/hw/ppc/pnv_lpc.c
> index 7d26b29487..0f14e180af 100644
> --- a/hw/ppc/pnv_lpc.c
> +++ b/hw/ppc/pnv_lpc.c
> @@ -64,6 +64,7 @@ enum {
>   #define   LPC_HC_IRQSER_START_4CLK      0x00000000
>   #define   LPC_HC_IRQSER_START_6CLK      0x01000000
>   #define   LPC_HC_IRQSER_START_8CLK      0x02000000
> +#define   LPC_HC_IRQSER_AUTO_CLEAR      0x00800000
>   #define LPC_HC_IRQMASK          0x34    /* same bit defs as LPC_HC_IRQSTAT */
>   #define LPC_HC_IRQSTAT          0x38
>   #define   LPC_HC_IRQ_SERIRQ0            0x80000000 /* all bits down to ... */
> @@ -420,32 +421,90 @@ static const MemoryRegionOps pnv_lpc_mmio_ops = {
>       .endianness = DEVICE_BIG_ENDIAN,
>   };
>   
> -static void pnv_lpc_eval_irqs(PnvLpcController *lpc)
> +/* Program the POWER9 LPC irq to PSI serirq routing table */
> +static void pnv_lpc_eval_serirq_routes(PnvLpcController *lpc)
>   {
> -    bool lpc_to_opb_irq = false;
> +    int irq;
>   
> -    /* Update LPC controller to OPB line */
> -    if (lpc->lpc_hc_irqser_ctrl & LPC_HC_IRQSER_EN) {
> -        uint32_t irqs;
> +    if (!lpc->psi_has_serirq) {
> +        if ((lpc->opb_irq_route0 & PPC_BITMASK(8, 13)) ||
> +            (lpc->opb_irq_route1 & PPC_BITMASK(4, 31))) {


Coverity reports an issue :

     CID 1558829:  Integer handling issues  (CONSTANT_EXPRESSION_RESULT)
     "lpc->opb_irq_route0 & (70931694131085312ULL /* (0x8000000000000000ULL >> 8) - (0x8000000000000000ULL >> 13) | (0x8000000000000000ULL >> 8) */)" is always 0 regardless of the values of its operands. This occurs as the logical first operand of "||".

Should the above if use PPC_BITMASK32 instead ?


> +            qemu_log_mask(LOG_GUEST_ERROR,
> +                "OPB: setting serirq routing on POWER8 system, ignoring.\n");
> +        }
> +        return;
> +    }
>   
> -        irqs = lpc->lpc_hc_irqstat & lpc->lpc_hc_irqmask;
> -        lpc_to_opb_irq = (irqs != 0);
> +    for (irq = 0; irq <= 13; irq++) {
> +        int serirq = (lpc->opb_irq_route1 >> (31 - 5 - (irq * 2))) & 0x3;
> +        lpc->irq_to_serirq_route[irq] = serirq;
>       }
>   
> -    /* We don't honor the polarity register, it's pointless and unused
> -     * anyway
> -     */
> -    if (lpc_to_opb_irq) {
> -        lpc->opb_irq_input |= OPB_MASTER_IRQ_LPC;
> -    } else {
> -        lpc->opb_irq_input &= ~OPB_MASTER_IRQ_LPC;
> +    for (irq = 14; irq < ISA_NUM_IRQS; irq++) {
> +        int serirq = (lpc->opb_irq_route0 >> (31 - 9 - (irq * 2))) & 0x3;


Coverity reports an issue :

     CID 1558828:    (BAD_SHIFT)
     In expression "lpc->opb_irq_route0 >> 22 - irq * 2", shifting by a negative amount has undefined behavior.  The shift amount, "22 - irq * 2", is -8.

The shift value (irq * 2) seems incorrect. should it be ((irq - 14) * 2) ?

Thanks,

C.



> +        lpc->irq_to_serirq_route[irq] = serirq;
> +    }
> +}
> +
> +static void pnv_lpc_eval_irqs(PnvLpcController *lpc)
> +{
> +    uint32_t active_irqs = 0;
> +
> +    if (lpc->lpc_hc_irqstat & PPC_BITMASK32(16, 31)) {
> +        qemu_log_mask(LOG_UNIMP, "LPC HC Unimplemented irqs in IRQSTAT: "
> +                                 "0x%08"PRIx32"\n", lpc->lpc_hc_irqstat);
>       }
>   
> -    /* Update OPB internal latch */
> -    lpc->opb_irq_stat |= lpc->opb_irq_input & lpc->opb_irq_mask;
> +    if (lpc->lpc_hc_irqser_ctrl & LPC_HC_IRQSER_EN) {
> +        active_irqs = lpc->lpc_hc_irqstat & lpc->lpc_hc_irqmask;
> +    }
>   
>       /* Reflect the interrupt */
> -    qemu_set_irq(lpc->psi_irq, lpc->opb_irq_stat != 0);
> +    if (!lpc->psi_has_serirq) {
> +        /*
> +         * POWER8 ORs all irqs together (also with LPCHC internal interrupt
> +         * sources) and outputs a single line that raises the PSI LPCHC irq
> +         * which then latches an OPB IRQ status register that sends the irq
> +         * to PSI.
> +         *
> +         * We don't honor the polarity register, it's pointless and unused
> +         * anyway
> +         */
> +        if (active_irqs) {
> +            lpc->opb_irq_input |= OPB_MASTER_IRQ_LPC;
> +        } else {
> +            lpc->opb_irq_input &= ~OPB_MASTER_IRQ_LPC;
> +        }
> +
> +        /* Update OPB internal latch */
> +        lpc->opb_irq_stat |= lpc->opb_irq_input & lpc->opb_irq_mask;
> +
> +        qemu_set_irq(lpc->psi_irq_lpchc, lpc->opb_irq_stat != 0);
> +    } else {
> +        /*
> +         * POWER9 and POWER10 have routing fields in OPB master registers that
> +         * send LPC irqs to 4 output lines that raise the PSI SERIRQ irqs.
> +         * These don't appear to get latched into an OPB register like the
> +         * LPCHC irqs.
> +         *
> +         * POWER9 LPC controller internal irqs still go via the OPB
> +         * and LPCHC PSI irqs like P8, but we have no such internal sources
> +         * modelled yet.
> +         */
> +        bool serirq_out[4] = { false, false, false, false };
> +        int irq;
> +
> +        for (irq = 0; irq < ISA_NUM_IRQS; irq++) {
> +            if (active_irqs & (LPC_HC_IRQ_SERIRQ0 >> irq)) {
> +                serirq_out[lpc->irq_to_serirq_route[irq]] = true;
> +            }
> +        }
> +
> +        qemu_set_irq(lpc->psi_irq_serirq[0], serirq_out[0]);
> +        qemu_set_irq(lpc->psi_irq_serirq[1], serirq_out[1]);
> +        qemu_set_irq(lpc->psi_irq_serirq[2], serirq_out[2]);
> +        qemu_set_irq(lpc->psi_irq_serirq[3], serirq_out[3]);
> +    }
>   }
>   
>   static uint64_t lpc_hc_read(void *opaque, hwaddr addr, unsigned size)
> @@ -543,10 +602,10 @@ static uint64_t opb_master_read(void *opaque, hwaddr addr, unsigned size)
>       uint64_t val = 0xfffffffffffffffful;
>   
>       switch (addr) {
> -    case OPB_MASTER_LS_ROUTE0: /* TODO */
> +    case OPB_MASTER_LS_ROUTE0:
>           val = lpc->opb_irq_route0;
>           break;
> -    case OPB_MASTER_LS_ROUTE1: /* TODO */
> +    case OPB_MASTER_LS_ROUTE1:
>           val = lpc->opb_irq_route1;
>           break;
>       case OPB_MASTER_LS_IRQ_STAT:
> @@ -575,11 +634,15 @@ static void opb_master_write(void *opaque, hwaddr addr,
>       PnvLpcController *lpc = opaque;
>   
>       switch (addr) {
> -    case OPB_MASTER_LS_ROUTE0: /* TODO */
> +    case OPB_MASTER_LS_ROUTE0:
>           lpc->opb_irq_route0 = val;
> +        pnv_lpc_eval_serirq_routes(lpc);
> +        pnv_lpc_eval_irqs(lpc);
>           break;
> -    case OPB_MASTER_LS_ROUTE1: /* TODO */
> +    case OPB_MASTER_LS_ROUTE1:
>           lpc->opb_irq_route1 = val;
> +        pnv_lpc_eval_serirq_routes(lpc);
> +        pnv_lpc_eval_irqs(lpc);
>           break;
>       case OPB_MASTER_LS_IRQ_STAT:
>           lpc->opb_irq_stat &= ~val;
> @@ -664,6 +727,8 @@ static void pnv_lpc_power9_realize(DeviceState *dev, Error **errp)
>       PnvLpcClass *plc = PNV_LPC_GET_CLASS(dev);
>       Error *local_err = NULL;
>   
> +    object_property_set_bool(OBJECT(lpc), "psi-serirq", true, &error_abort);
> +
>       plc->parent_realize(dev, &local_err);
>       if (local_err) {
>           error_propagate(errp, local_err);
> @@ -673,6 +738,9 @@ static void pnv_lpc_power9_realize(DeviceState *dev, Error **errp)
>       /* P9 uses a MMIO region */
>       memory_region_init_io(&lpc->xscom_regs, OBJECT(lpc), &pnv_lpc_mmio_ops,
>                             lpc, "lpcm", PNV9_LPCM_SIZE);
> +
> +    /* P9 LPC routes ISA irqs to 4 PSI SERIRQ lines */
> +    qdev_init_gpio_out_named(dev, lpc->psi_irq_serirq, "SERIRQ", 4);
>   }
>   
>   static void pnv_lpc_power9_class_init(ObjectClass *klass, void *data)
> @@ -751,13 +819,19 @@ static void pnv_lpc_realize(DeviceState *dev, Error **errp)
>       memory_region_add_subregion(&lpc->opb_mr, LPC_HC_REGS_OPB_ADDR,
>                                   &lpc->lpc_hc_regs);
>   
> -    qdev_init_gpio_out(dev, &lpc->psi_irq, 1);
> +    qdev_init_gpio_out_named(dev, &lpc->psi_irq_lpchc, "LPCHC", 1);
>   }
>   
> +static Property pnv_lpc_properties[] = {
> +    DEFINE_PROP_BOOL("psi-serirq", PnvLpcController, psi_has_serirq, false),
> +    DEFINE_PROP_END_OF_LIST(),
> +};
> +
>   static void pnv_lpc_class_init(ObjectClass *klass, void *data)
>   {
>       DeviceClass *dc = DEVICE_CLASS(klass);
>   
> +    device_class_set_props(dc, pnv_lpc_properties);
>       dc->realize = pnv_lpc_realize;
>       dc->desc = "PowerNV LPC Controller";
>       dc->user_creatable = false;
> @@ -803,7 +877,7 @@ static void pnv_lpc_isa_irq_handler_cpld(void *opaque, int n, int level)
>       }
>   
>       if (pnv->cpld_irqstate != old_state) {
> -        qemu_set_irq(lpc->psi_irq, pnv->cpld_irqstate != 0);
> +        qemu_set_irq(lpc->psi_irq_lpchc, pnv->cpld_irqstate != 0);
>       }
>   }
>   
> @@ -824,6 +898,13 @@ static void pnv_lpc_isa_irq_handler(void *opaque, int n, int level)
>           pnv_lpc_eval_irqs(lpc);
>       } else {
>           lpc->lpc_hc_irq_inputs &= ~irq_bit;
> +
> +        /* POWER9 adds an auto-clear mode that clears IRQSTAT bits on EOI */
> +        if (lpc->psi_has_serirq &&
> +            (lpc->lpc_hc_irqser_ctrl & LPC_HC_IRQSER_AUTO_CLEAR)) {
> +            lpc->lpc_hc_irqstat &= ~irq_bit;
> +            pnv_lpc_eval_irqs(lpc);
> +        }
>       }
>   }
>   
> @@ -854,6 +935,7 @@ ISABus *pnv_lpc_isa_create(PnvLpcController *lpc, bool use_cpld, Error **errp)
>           handler = pnv_lpc_isa_irq_handler;
>       }
>   
> +    /* POWER has a 17th irq, QEMU only implements the 16 regular device irqs */
>       irqs = qemu_allocate_irqs(handler, lpc, ISA_NUM_IRQS);
>   
>       isa_bus_register_input_irqs(isa_bus, irqs);
> diff --git a/include/hw/ppc/pnv_lpc.h b/include/hw/ppc/pnv_lpc.h
> index 97c6872c3f..e0fd5e4130 100644
> --- a/include/hw/ppc/pnv_lpc.h
> +++ b/include/hw/ppc/pnv_lpc.h
> @@ -23,6 +23,7 @@
>   #include "exec/memory.h"
>   #include "hw/ppc/pnv.h"
>   #include "hw/qdev-core.h"
> +#include "hw/isa/isa.h" /* For ISA_NUM_IRQS */
>   
>   #define TYPE_PNV_LPC "pnv-lpc"
>   typedef struct PnvLpcClass PnvLpcClass;
> @@ -87,8 +88,19 @@ struct PnvLpcController {
>       /* XSCOM registers */
>       MemoryRegion xscom_regs;
>   
> +    /*
> +     * In P8, ISA irqs are combined with internal sources to drive the
> +     * LPCHC interrupt output. P9 ISA irqs raise one of 4 lines that
> +     * drive PSI SERIRQ irqs, routing according to OPB routing registers.
> +     */
> +    bool psi_has_serirq;
> +
>       /* PSI to generate interrupts */
> -    qemu_irq psi_irq;
> +    qemu_irq psi_irq_lpchc;
> +
> +    /* P9 serirq lines and irq routing table */
> +    qemu_irq psi_irq_serirq[4];
> +    int irq_to_serirq_route[ISA_NUM_IRQS];
>   };
>   
>   struct PnvLpcClass {