[PATCH v4 01/15] lib: ipi: Adjust Andes PLICSW to single-bit-per-hart scheme
Anup Patel
anup at brainfault.org
Wed Dec 6 04:03:35 PST 2023
On Thu, Nov 30, 2023 at 6:12 PM Yu Chien Peter Lin
<peterlin at andestech.com> wrote:
>
> From: Leo Yu-Chi Liang <ycliang at andestech.com>
>
> The old scheme doesn't allow sending hart0 self-IPI as the
> corresponding bit on pending register is hardwired to 0, this
> could lead to unhandle IPIs on SMP systems, esp. on single-core.
>
> Furthermore, the limitation of old scheme is 8-core, instead of
> reserving source hart information, we assign bit (x + 1) as the
> enable and pending bit of hartx, this also expands the bootable
> hart number.
>
> The following diagram shows the enable bits of the new scheme
> on 32-core Andes platform.
>
> Pending regs: 0x1000 x---0---0---0---0------0---0
> Pending hart ID: 0 1 2 3 ... 30 31
> Interrupt ID: 0 1 2 3 4 ... 31 32
> | | | | | | |
> Enable regs: 0x2000 x---1---0---0---0-...--0---0---> hart0
> | | | | | | |
> 0x2080 x---0---1---0---0-...--0---0---> hart1
> | | | | | | |
> 0x2100 x---0---0---1---0-...--0---0---> hart2
> | | | | | | |
> 0x2180 x---0---0---0---1-...--0---0---> hart3
> . . . . . . .
> . . . . . . .
> . . . . . . .
> 0x2f00 x---0---0---0---0-...--1---0---> hart30
> | | | | | | |
> 0x2f80 x---0---0---0---0-...--0---1---> hart31
> <-------- word 0 -------><--- word 1 --->
>
> To send IPI to hart0, for example, another hart (including hart0
> itself) will set bit 1 of first word on the pending register.
>
> We also fix indentation in andes_plicsw.h along with this patch.
>
> Fixes: ce7c490719ed ("lib: utils/ipi: Add Andes fdt ipi driver support")
> Signed-off-by: Leo Yu-Chi Liang <ycliang at andestech.com>
> Reviewed-by: Yu Chien Peter Lin <peterlin at andestech.com>
> Reviewed-by: Randolph <randolph at andestech.com>
> Reported-by: Lad Prabhakar <prabhakar.mahadev-lad.rj at bp.renesas.com>
> Link: https://lists.infradead.org/pipermail/opensbi/2023-October/005665.html
> Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj at bp.renesas.com>
> Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj at bp.renesas.com>
Looks good to me.
Reviewed-by: Anup Patel <anup at brainfault.org>
Regards,
Anup
> ---
> Changes v2 -> v3:
> - New patch
> Changes v3 -> v4:
> - Include Prabhakar's RB & TB tags
> ---
> include/sbi_utils/ipi/andes_plicsw.h | 23 +++---
> lib/utils/ipi/andes_plicsw.c | 104 ++++++++++-----------------
> 2 files changed, 46 insertions(+), 81 deletions(-)
>
> diff --git a/include/sbi_utils/ipi/andes_plicsw.h b/include/sbi_utils/ipi/andes_plicsw.h
> index e93cda0..0d18444 100644
> --- a/include/sbi_utils/ipi/andes_plicsw.h
> +++ b/include/sbi_utils/ipi/andes_plicsw.h
> @@ -13,30 +13,23 @@
> #ifndef _IPI_ANDES_PLICSW_H_
> #define _IPI_ANDES_PLICSW_H_
>
> -#define PLICSW_PRIORITY_BASE 0x4
> +#define PLICSW_PRIORITY_BASE 0x4
>
> -#define PLICSW_PENDING_BASE 0x1000
> -#define PLICSW_PENDING_STRIDE 0x8
> +#define PLICSW_PENDING_BASE 0x1000
>
> -#define PLICSW_ENABLE_BASE 0x2000
> -#define PLICSW_ENABLE_STRIDE 0x80
> +#define PLICSW_ENABLE_BASE 0x2000
> +#define PLICSW_ENABLE_STRIDE 0x80
>
> -#define PLICSW_CONTEXT_BASE 0x200000
> -#define PLICSW_CONTEXT_STRIDE 0x1000
> -#define PLICSW_CONTEXT_CLAIM 0x4
> +#define PLICSW_CONTEXT_BASE 0x200000
> +#define PLICSW_CONTEXT_STRIDE 0x1000
> +#define PLICSW_CONTEXT_CLAIM 0x4
>
> -#define PLICSW_HART_MASK 0x01010101
> -
> -#define PLICSW_HART_MAX_NR 8
> -
> -#define PLICSW_REGION_ALIGN 0x1000
> +#define PLICSW_REGION_ALIGN 0x1000
>
> struct plicsw_data {
> unsigned long addr;
> unsigned long size;
> uint32_t hart_count;
> - /* hart id to source id table */
> - uint32_t source_id[PLICSW_HART_MAX_NR];
> };
>
> int plicsw_warm_ipi_init(void);
> diff --git a/lib/utils/ipi/andes_plicsw.c b/lib/utils/ipi/andes_plicsw.c
> index 5693efb..413ac20 100644
> --- a/lib/utils/ipi/andes_plicsw.c
> +++ b/lib/utils/ipi/andes_plicsw.c
> @@ -18,77 +18,45 @@
>
> struct plicsw_data plicsw;
>
> -static inline void plicsw_claim(void)
> +static void plicsw_ipi_send(u32 hart_index)
> {
> - u32 hartid = current_hartid();
> + ulong pending_reg;
> + u32 interrupt_id, word_index, pending_bit;
> + u32 target_hart = sbi_hartindex_to_hartid(hart_index);
>
> - if (plicsw.hart_count <= hartid)
> + if (plicsw.hart_count <= target_hart)
> ebreak();
>
> - plicsw.source_id[hartid] =
> - readl((void *)plicsw.addr + PLICSW_CONTEXT_BASE +
> - PLICSW_CONTEXT_CLAIM + PLICSW_CONTEXT_STRIDE * hartid);
> -}
> -
> -static inline void plicsw_complete(void)
> -{
> - u32 hartid = current_hartid();
> - u32 source = plicsw.source_id[hartid];
> -
> - writel(source, (void *)plicsw.addr + PLICSW_CONTEXT_BASE +
> - PLICSW_CONTEXT_CLAIM +
> - PLICSW_CONTEXT_STRIDE * hartid);
> -}
> -
> -static inline void plic_sw_pending(u32 target_hart)
> -{
> /*
> - * The pending array registers are w1s type.
> - * IPI pending array mapping as following:
> - *
> - * Pending array start address: base + 0x1000
> - * ---------------------------------
> - * | hart3 | hart2 | hart1 | hart0 |
> - * ---------------------------------
> - * Each hartX can send IPI to another hart by setting the
> - * bitY to its own region (see the below).
> - *
> - * In each hartX region:
> - * <---------- PICSW_PENDING_STRIDE -------->
> - * | bit7 | ... | bit3 | bit2 | bit1 | bit0 |
> - * ------------------------------------------
> - * The bitY of hartX region indicates that hartX sends an
> - * IPI to hartY.
> + * We assign a single bit for each hart.
> + * Bit 0 is hardwired to 0, thus unavailable.
> + * Bit(X+1) indicates that IPI is sent to hartX.
> */
> - u32 hartid = current_hartid();
> - u32 word_index = hartid / 4;
> - u32 per_hart_offset = PLICSW_PENDING_STRIDE * hartid;
> - u32 val = 1 << target_hart << per_hart_offset;
> + interrupt_id = target_hart + 1;
> + word_index = interrupt_id / 32;
> + pending_bit = interrupt_id % 32;
> + pending_reg = plicsw.addr + PLICSW_PENDING_BASE + word_index * 4;
>
> - writel(val, (void *)plicsw.addr + PLICSW_PENDING_BASE + word_index * 4);
> + /* Set target hart's mip.MSIP */
> + writel_relaxed(BIT(pending_bit), (void *)pending_reg);
> }
>
> -static void plicsw_ipi_send(u32 hart_index)
> +static void plicsw_ipi_clear(u32 hart_index)
> {
> u32 target_hart = sbi_hartindex_to_hartid(hart_index);
> + ulong reg = plicsw.addr + PLICSW_CONTEXT_BASE + PLICSW_CONTEXT_CLAIM +
> + PLICSW_CONTEXT_STRIDE * target_hart;
>
> if (plicsw.hart_count <= target_hart)
> ebreak();
>
> - /* Set PLICSW IPI */
> - plic_sw_pending(target_hart);
> -}
> + /* Claim */
> + u32 source = readl((void *)reg);
>
> -static void plicsw_ipi_clear(u32 hart_index)
> -{
> - u32 target_hart = sbi_hartindex_to_hartid(hart_index);
> -
> - if (plicsw.hart_count <= target_hart)
> - ebreak();
> + /* A successful claim will clear mip.MSIP */
>
> - /* Clear PLICSW IPI */
> - plicsw_claim();
> - plicsw_complete();
> + /* Complete */
> + writel(source, (void *)reg);
> }
>
> static struct sbi_ipi_device plicsw_ipi = {
> @@ -110,22 +78,26 @@ int plicsw_warm_ipi_init(void)
> int plicsw_cold_ipi_init(struct plicsw_data *plicsw)
> {
> int rc;
> + u32 interrupt_id, word_index, enable_bit;
> + ulong enable_reg, priority_reg;
>
> /* Setup source priority */
> - uint32_t *priority = (void *)plicsw->addr + PLICSW_PRIORITY_BASE;
> -
> - for (int i = 0; i < plicsw->hart_count; i++)
> - writel(1, &priority[i]);
> -
> - /* Setup target enable */
> - uint32_t enable_mask = PLICSW_HART_MASK;
> + for (int i = 0; i < plicsw->hart_count; i++) {
> + priority_reg = plicsw->addr + PLICSW_PRIORITY_BASE + i * 4;
> + writel(1, (void *)priority_reg);
> + }
>
> + /*
> + * Setup enable for each hart, skip non-existent interrupt ID 0
> + * which is hardwired to 0.
> + */
> for (int i = 0; i < plicsw->hart_count; i++) {
> - uint32_t *enable = (void *)plicsw->addr + PLICSW_ENABLE_BASE +
> - PLICSW_ENABLE_STRIDE * i;
> - writel(enable_mask, enable);
> - writel(enable_mask, enable + 1);
> - enable_mask <<= 1;
> + interrupt_id = i + 1;
> + word_index = interrupt_id / 32;
> + enable_bit = interrupt_id % 32;
> + enable_reg = plicsw->addr + PLICSW_ENABLE_BASE +
> + PLICSW_ENABLE_STRIDE * i + 4 * word_index;
> + writel(BIT(enable_bit), (void *)enable_reg);
> }
>
> /* Add PLICSW region to the root domain */
> --
> 2.34.1
>
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