linux-kernel - [PATCH V3 2/2] irqchip/sifive-plic: Add thead,c900-plic support

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Date:   Wed, 13 Oct 2021 09:21:49 +0800
From:   guoren@...nel.org
To:     guoren@...nel.org, anup@...infault.org, atish.patra@....com,
        maz@...nel.org, tglx@...utronix.de, palmer@...belt.com,
        heiko@...ech.de
Cc:     linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
        Guo Ren <guoren@...ux.alibaba.com>
Subject: [PATCH V3 2/2] irqchip/sifive-plic: Add thead,c900-plic support

From: Guo Ren <guoren@...ux.alibaba.com>

thead,c900-plic would mask IRQ with readl(claim), so it needn't
mask/unmask which needed in RISC-V PLIC.

When in IRQS_ONESHOT & IRQCHIP_EOI_THREADED path, unnecessary mask
operation would cause a blocking irq bug in thead,c900-plic. Because
when IRQ is disabled in c900, writel(hwirq, claim) would be invalid.

Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
Cc: Anup Patel <anup@...infault.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Marc Zyngier <maz@...nel.org>
Cc: Palmer Dabbelt <palmer@...belt.com>
Cc: Atish Patra <atish.patra@....com>

---

Changes since V3:
 - Rename "c9xx" to "c900"
 - Add sifive_plic_chip and thead_plic_chip for difference

Changes since V2:
 - Add a separate compatible string "thead,c9xx-plic"
 - set irq_mask/unmask of "plic_chip" to NULL and point
   irq_enable/disable of "plic_chip" to plic_irq_mask/unmask
 - Add a detailed comment block in plic_init() about the
   differences in Claim/Completion process of RISC-V PLIC and C9xx
   PLIC.
---
 drivers/irqchip/irq-sifive-plic.c | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
index cf74cfa82045..5b806d823df7 100644
--- a/drivers/irqchip/irq-sifive-plic.c
+++ b/drivers/irqchip/irq-sifive-plic.c
@@ -166,7 +166,7 @@ static void plic_irq_eoi(struct irq_data *d)
 	writel(d->hwirq, handler->hart_base + CONTEXT_CLAIM);
 }
 
-static struct irq_chip plic_chip = {
+static struct irq_chip sifive_plic_chip = {
 	.name		= "SiFive PLIC",
 	.irq_mask	= plic_irq_mask,
 	.irq_unmask	= plic_irq_unmask,
@@ -176,12 +176,24 @@ static struct irq_chip plic_chip = {
 #endif
 };
 
+static struct irq_chip thead_plic_chip = {
+	.name		= "T-Head PLIC",
+	.irq_disable	= plic_irq_mask,
+	.irq_enable	= plic_irq_unmask,
+	.irq_eoi	= plic_irq_eoi,
+#ifdef CONFIG_SMP
+	.irq_set_affinity = plic_set_affinity,
+#endif
+};
+
+static struct irq_chip *def_plic_chip = &sifive_plic_chip;
+
 static int plic_irqdomain_map(struct irq_domain *d, unsigned int irq,
 			      irq_hw_number_t hwirq)
 {
 	struct plic_priv *priv = d->host_data;
 
-	irq_domain_set_info(d, irq, hwirq, &plic_chip, d->host_data,
+	irq_domain_set_info(d, irq, hwirq, def_plic_chip, d->host_data,
 			    handle_fasteoi_irq, NULL, NULL);
 	irq_set_noprobe(irq);
 	irq_set_affinity(irq, &priv->lmask);
@@ -390,5 +402,14 @@ static int __init plic_init(struct device_node *node,
 	return error;
 }
 
+static int __init thead_c900_plic_init(struct device_node *node,
+		struct device_node *parent)
+{
+	def_plic_chip = &thead_plic_chip;
+
+	return plic_init(node, parent);
+}
+
 IRQCHIP_DECLARE(sifive_plic, "sifive,plic-1.0.0", plic_init);
 IRQCHIP_DECLARE(riscv_plic0, "riscv,plic0", plic_init); /* for legacy systems */
+IRQCHIP_DECLARE(thead_c900_plic, "thead,c900-plic", thead_c900_plic_init);
-- 
2.25.1