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Thu, 16 Oct 2025 01:43:22 -0700 (PDT) X-Google-Smtp-Source: AGHT+IE87h87L5+cjbKqDzFGeScqw+GJyAWKB/ZTf9y7pe94sr7jbGPA3jOKyUr3qhAx/eeHS0qseQ== X-Received: by 2002:a05:6000:40c9:b0:426:d619:cac7 with SMTP id ffacd0b85a97d-426d619cd64mr12707369f8f.36.1760604201696; Thu, 16 Oct 2025 01:43:21 -0700 (PDT) Received: from holism.lzampier.com ([148.252.9.235]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-426ce5e1284sm33047565f8f.45.2025.10.16.01.43.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Oct 2025 01:43:21 -0700 (PDT) From: Lucas Zampieri To: linux-kernel@vger.kernel.org Cc: Charles Mirabile , Thomas Gleixner , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Paul Walmsley , Samuel Holland , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Vivian Wang , devicetree@vger.kernel.org, linux-riscv@lists.infradead.org, Zhang Xincheng , Lucas Zampieri Subject: [PATCH v5 3/3] irqchip/plic: add support for UltraRISC DP1000 PLIC Date: Thu, 16 Oct 2025 09:42:56 +0100 Message-ID: <20251016084301.27670-4-lzampier@redhat.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251016084301.27670-1-lzampier@redhat.com> References: <20251016084301.27670-1-lzampier@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Charles Mirabile Add a new compatible for the plic found in UltraRISC DP1000 with a quirk to work around a known hardware bug with IRQ claiming in the UR-CP100 cores. When claiming an interrupt on UR-CP100 cores, all other interrupts must be disabled before the claim register is accessed to prevent incorrect handling of the interrupt. This is a hardware bug in the CP100 core implementation, not specific to the DP1000 SoC. When the PLIC_QUIRK_CP100_CLAIM_REGISTER_ERRATUM flag is present, a specialized handler (plic_handle_irq_cp100) saves the enable state of all interrupts, disables all interrupts except for the first pending one before reading the claim register, and then restores the interrupts before further processing of the claimed interrupt continues. The driver matches on "ultrarisc,cp100-plic" to apply the quirk to all SoCs using UR-CP100 cores, regardless of the specific SoC implementation. This has no impact on other platforms. Co-developed-by: Zhang Xincheng Signed-off-by: Zhang Xincheng Signed-off-by: Charles Mirabile Acked-by: Samuel Holland Signed-off-by: Lucas Zampieri --- drivers/irqchip/irq-sifive-plic.c | 94 ++++++++++++++++++++++++++++++- 1 file changed, 93 insertions(+), 1 deletion(-) diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c index bf69a4802b71..0428e9f3423d 100644 --- a/drivers/irqchip/irq-sifive-plic.c +++ b/drivers/irqchip/irq-sifive-plic.c @@ -49,6 +49,8 @@ #define CONTEXT_ENABLE_BASE 0x2000 #define CONTEXT_ENABLE_SIZE 0x80 +#define PENDING_BASE 0x1000 + /* * Each hart context has a set of control registers associated with it. Right * now there's only two: a source priority threshold over which the hart will @@ -63,6 +65,7 @@ #define PLIC_ENABLE_THRESHOLD 0 #define PLIC_QUIRK_EDGE_INTERRUPT 0 +#define PLIC_QUIRK_CP100_CLAIM_REGISTER_ERRATUM 1 struct plic_priv { struct fwnode_handle *fwnode; @@ -394,6 +397,89 @@ static void plic_handle_irq(struct irq_desc *desc) chained_irq_exit(chip, desc); } +static bool cp100_isolate_pending_irq(int nr_irq_groups, u32 ie[], + void __iomem *pending, + void __iomem *enable) +{ + u32 pending_irqs = 0; + int i, j; + + /* Look for first pending interrupt */ + for (i = 0; i < nr_irq_groups; i++) { + pending_irqs = ie[i] & readl_relaxed(pending + i * sizeof(u32)); + if (pending_irqs) + break; + } + + if (!pending_irqs) + return false; + + /* Disable all interrupts but the first pending one */ + for (j = 0; j < nr_irq_groups; j++) { + u32 new_mask = 0; + + if (j == i) { + /* Extract mask with lowest set bit */ + new_mask = (pending_irqs & -pending_irqs); + } + + writel_relaxed(new_mask, enable + j * sizeof(u32)); + } + + return true; +} + +static irq_hw_number_t cp100_get_hwirq(struct plic_handler *handler, + void __iomem *claim) +{ + int nr_irq_groups = DIV_ROUND_UP(handler->priv->nr_irqs, 32); + void __iomem *pending = handler->priv->regs + PENDING_BASE; + void __iomem *enable = handler->enable_base; + irq_hw_number_t hwirq = 0; + int i; + + guard(raw_spinlock)(&handler->enable_lock); + + /* Save current interrupt enable state */ + for (i = 0; i < nr_irq_groups; i++) + handler->enable_save[i] = readl_relaxed(enable + i * sizeof(u32)); + + if (!cp100_isolate_pending_irq(nr_irq_groups, handler->enable_save, pending, enable)) + return 0; + + hwirq = readl(claim); + + /* Restore previous state */ + for (i = 0; i < nr_irq_groups; i++) + writel_relaxed(handler->enable_save[i], enable + i * sizeof(u32)); + + return hwirq; +} + +static void plic_handle_irq_cp100(struct irq_desc *desc) +{ + struct plic_handler *handler = this_cpu_ptr(&plic_handlers); + struct irq_chip *chip = irq_desc_get_chip(desc); + void __iomem *claim = handler->hart_base + CONTEXT_CLAIM; + irq_hw_number_t hwirq; + + WARN_ON_ONCE(!handler->present); + + chained_irq_enter(chip, desc); + + while ((hwirq = cp100_get_hwirq(handler, claim))) { + int err = generic_handle_domain_irq(handler->priv->irqdomain, hwirq); + + if (unlikely(err)) { + pr_warn_ratelimited("%pfwP: can't find mapping for hwirq %lu\n", + handler->priv->fwnode, hwirq); + } + } + + chained_irq_exit(chip, desc); +} + static void plic_set_threshold(struct plic_handler *handler, u32 threshold) { /* priority must be > threshold to trigger an interrupt */ @@ -430,6 +516,8 @@ static const struct of_device_id plic_match[] = { .data = (const void *)BIT(PLIC_QUIRK_EDGE_INTERRUPT) }, { .compatible = "thead,c900-plic", .data = (const void *)BIT(PLIC_QUIRK_EDGE_INTERRUPT) }, + { .compatible = "ultrarisc,cp100-plic", + .data = (const void *)BIT(PLIC_QUIRK_CP100_CLAIM_REGISTER_ERRATUM) }, {} }; @@ -664,12 +752,16 @@ static int plic_probe(struct fwnode_handle *fwnode) } if (global_setup) { + void (*handler_fn)(struct irq_desc *) = plic_handle_irq; + + if (test_bit(PLIC_QUIRK_CP100_CLAIM_REGISTER_ERRATUM, &handler->priv->plic_quirks)) + handler_fn = plic_handle_irq_cp100; + /* Find parent domain and register chained handler */ domain = irq_find_matching_fwnode(riscv_get_intc_hwnode(), DOMAIN_BUS_ANY); if (domain) plic_parent_irq = irq_create_mapping(domain, RV_IRQ_EXT); if (plic_parent_irq) - irq_set_chained_handler(plic_parent_irq, plic_handle_irq); + irq_set_chained_handler(plic_parent_irq, handler_fn); cpuhp_setup_state(CPUHP_AP_IRQ_SIFIVE_PLIC_STARTING, "irqchip/sifive/plic:starting", -- 2.51.0