irqchip: add C-SKY APB bus interrupt controller

The driver is for C-SKY APB bus interrupt controller. It's a simple
interrupt controller which use pending reg to detect the irq and use
enable/disable reg to mask/unmask interrupt sources.

A lot of SOCs based on C-SKY CPU use the interrupt controller as root
controller.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>

3 files changed, 283 insertions, 0 deletions

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 8103f6f99dff..41cdca02f053 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -380,6 +380,14 @@ config CSKY_MPINTC
 	  In fact it's not mmio map in hw and it use ld/st to visit the
 	  controller's register inside CPU.
 
+config CSKY_APB_INTC
+	bool "C-SKY APB Interrupt Controller"
+	depends on CSKY
+	help
+	  Say yes here to enable C-SKY APB interrupt controller driver used
+	  by C-SKY single core SOC system. It use mmio map apb-bus to visit
+	  the controller's register.
+
 endmenu
 
 config SIFIVE_PLIC
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index 6b739ea27f85..72eaf5353af2 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -88,4 +88,5 @@ obj-$(CONFIG_GOLDFISH_PIC) 		+= irq-goldfish-pic.o
 obj-$(CONFIG_NDS32)			+= irq-ativic32.o
 obj-$(CONFIG_QCOM_PDC)			+= qcom-pdc.o
 obj-$(CONFIG_CSKY_MPINTC)		+= irq-csky-mpintc.o
+obj-$(CONFIG_CSKY_APB_INTC)		+= irq-csky-apb-intc.o
 obj-$(CONFIG_SIFIVE_PLIC)		+= irq-sifive-plic.o
diff --git a/drivers/irqchip/irq-csky-apb-intc.c b/drivers/irqchip/irq-csky-apb-intc.c
new file mode 100644
index 000000000000..2543baba8b1f
--- /dev/null
+++ b/drivers/irqchip/irq-csky-apb-intc.c
@@ -0,0 +1,274 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/module.h>
+#include <linux/irqdomain.h>
+#include <linux/irqchip.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <asm/irq.h>
+
+#define INTC_IRQS		64
+
+#define CK_INTC_ICR		0x00
+#define CK_INTC_PEN31_00	0x14
+#define CK_INTC_PEN63_32	0x2c
+#define CK_INTC_NEN31_00	0x10
+#define CK_INTC_NEN63_32	0x28
+#define CK_INTC_SOURCE		0x40
+#define CK_INTC_DUAL_BASE	0x100
+
+#define GX_INTC_PEN31_00	0x00
+#define GX_INTC_PEN63_32	0x04
+#define GX_INTC_NEN31_00	0x40
+#define GX_INTC_NEN63_32	0x44
+#define GX_INTC_NMASK31_00	0x50
+#define GX_INTC_NMASK63_32	0x54
+#define GX_INTC_SOURCE		0x60
+
+static void __iomem *reg_base;
+static struct irq_domain *root_domain;
+
+static int nr_irq = INTC_IRQS;
+
+/*
+ * When controller support pulse signal, the PEN_reg will hold on signal
+ * without software trigger.
+ *
+ * So, to support pulse signal we need to clear IFR_reg and the address of
+ * IFR_offset is NEN_offset - 8.
+ */
+static void irq_ck_mask_set_bit(struct irq_data *d)
+{
+	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
+	struct irq_chip_type *ct = irq_data_get_chip_type(d);
+	unsigned long ifr = ct->regs.mask - 8;
+	u32 mask = d->mask;
+
+	irq_gc_lock(gc);
+	*ct->mask_cache |= mask;
+	irq_reg_writel(gc, *ct->mask_cache, ct->regs.mask);
+	irq_reg_writel(gc, irq_reg_readl(gc, ifr) & ~mask, ifr);
+	irq_gc_unlock(gc);
+}
+
+static void __init ck_set_gc(struct device_node *node, void __iomem *reg_base,
+			     u32 mask_reg, u32 irq_base)
+{
+	struct irq_chip_generic *gc;
+
+	gc = irq_get_domain_generic_chip(root_domain, irq_base);
+	gc->reg_base = reg_base;
+	gc->chip_types[0].regs.mask = mask_reg;
+	gc->chip_types[0].chip.irq_mask = irq_gc_mask_clr_bit;
+	gc->chip_types[0].chip.irq_unmask = irq_gc_mask_set_bit;
+
+	if (of_find_property(node, "csky,support-pulse-signal", NULL))
+		gc->chip_types[0].chip.irq_unmask = irq_ck_mask_set_bit;
+}
+
+static inline u32 build_channel_val(u32 idx, u32 magic)
+{
+	u32 res;
+
+	/*
+	 * Set the same index for each channel
+	 */
+	res = idx | (idx << 8) | (idx << 16) | (idx << 24);
+
+	/*
+	 * Set the channel magic number in descending order.
+	 * The magic is 0x00010203 for ck-intc
+	 * The magic is 0x03020100 for gx6605s-intc
+	 */
+	return res | magic;
+}
+
+static inline void setup_irq_channel(u32 magic, void __iomem *reg_addr)
+{
+	u32 i;
+
+	/* Setup 64 channel slots */
+	for (i = 0; i < INTC_IRQS; i += 4)
+		writel_relaxed(build_channel_val(i, magic), reg_addr + i);
+}
+
+static int __init
+ck_intc_init_comm(struct device_node *node, struct device_node *parent)
+{
+	int ret;
+
+	if (parent) {
+		pr_err("C-SKY Intc not a root irq controller\n");
+		return -EINVAL;
+	}
+
+	reg_base = of_iomap(node, 0);
+	if (!reg_base) {
+		pr_err("C-SKY Intc unable to map: %p.\n", node);
+		return -EINVAL;
+	}
+
+	root_domain = irq_domain_add_linear(node, nr_irq,
+					    &irq_generic_chip_ops, NULL);
+	if (!root_domain) {
+		pr_err("C-SKY Intc irq_domain_add failed.\n");
+		return -ENOMEM;
+	}
+
+	ret = irq_alloc_domain_generic_chips(root_domain, 32, 1,
+			"csky_intc", handle_level_irq,
+			IRQ_NOREQUEST | IRQ_NOPROBE | IRQ_NOAUTOEN, 0, 0);
+	if (ret) {
+		pr_err("C-SKY Intc irq_alloc_gc failed.\n");
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static inline bool handle_irq_perbit(struct pt_regs *regs, u32 hwirq,
+				     u32 irq_base)
+{
+	u32 irq;
+
+	if (hwirq == 0)
+		return 0;
+
+	while (hwirq) {
+		irq = __ffs(hwirq);
+		hwirq &= ~BIT(irq);
+		handle_domain_irq(root_domain, irq_base + irq, regs);
+	}
+
+	return 1;
+}
+
+/* gx6605s 64 irqs interrupt controller */
+static void gx_irq_handler(struct pt_regs *regs)
+{
+	bool ret;
+
+	do {
+		ret  = handle_irq_perbit(regs,
+				readl_relaxed(reg_base + GX_INTC_PEN31_00), 0);
+		ret |= handle_irq_perbit(regs,
+				readl_relaxed(reg_base + GX_INTC_PEN63_32), 32);
+	} while (ret);
+}
+
+static int __init
+gx_intc_init(struct device_node *node, struct device_node *parent)
+{
+	int ret;
+
+	ret = ck_intc_init_comm(node, parent);
+	if (ret)
+		return ret;
+
+	/*
+	 * Initial enable reg to disable all interrupts
+	 */
+	writel_relaxed(0x0, reg_base + GX_INTC_NEN31_00);
+	writel_relaxed(0x0, reg_base + GX_INTC_NEN63_32);
+
+	/*
+	 * Initial mask reg with all unmasked, because we only use enalbe reg
+	 */
+	writel_relaxed(0x0, reg_base + GX_INTC_NMASK31_00);
+	writel_relaxed(0x0, reg_base + GX_INTC_NMASK63_32);
+
+	setup_irq_channel(0x03020100, reg_base + GX_INTC_SOURCE);
+
+	ck_set_gc(node, reg_base, GX_INTC_NEN31_00, 0);
+	ck_set_gc(node, reg_base, GX_INTC_NEN63_32, 32);
+
+	set_handle_irq(gx_irq_handler);
+
+	return 0;
+}
+IRQCHIP_DECLARE(csky_gx6605s_intc, "csky,gx6605s-intc", gx_intc_init);
+
+/*
+ * C-SKY simple 64 irqs interrupt controller, dual-together could support 128
+ * irqs.
+ */
+static void ck_irq_handler(struct pt_regs *regs)
+{
+	bool ret;
+	void __iomem *reg_pen_lo = reg_base + CK_INTC_PEN31_00;
+	void __iomem *reg_pen_hi = reg_base + CK_INTC_PEN63_32;
+
+	do {
+		/* handle 0 - 31 irqs */
+		ret  = handle_irq_perbit(regs, readl_relaxed(reg_pen_lo), 0);
+		ret |= handle_irq_perbit(regs, readl_relaxed(reg_pen_hi), 32);
+
+		if (nr_irq == INTC_IRQS)
+			continue;
+
+		/* handle 64 - 127 irqs */
+		ret |= handle_irq_perbit(regs,
+			readl_relaxed(reg_pen_lo + CK_INTC_DUAL_BASE), 64);
+		ret |= handle_irq_perbit(regs,
+			readl_relaxed(reg_pen_hi + CK_INTC_DUAL_BASE), 96);
+	} while (ret);
+}
+
+static int __init
+ck_intc_init(struct device_node *node, struct device_node *parent)
+{
+	int ret;
+
+	ret = ck_intc_init_comm(node, parent);
+	if (ret)
+		return ret;
+
+	/* Initial enable reg to disable all interrupts */
+	writel_relaxed(0, reg_base + CK_INTC_NEN31_00);
+	writel_relaxed(0, reg_base + CK_INTC_NEN63_32);
+
+	/* Enable irq intc */
+	writel_relaxed(BIT(31), reg_base + CK_INTC_ICR);
+
+	ck_set_gc(node, reg_base, CK_INTC_NEN31_00, 0);
+	ck_set_gc(node, reg_base, CK_INTC_NEN63_32, 32);
+
+	setup_irq_channel(0x00010203, reg_base + CK_INTC_SOURCE);
+
+	set_handle_irq(ck_irq_handler);
+
+	return 0;
+}
+IRQCHIP_DECLARE(ck_intc, "csky,apb-intc", ck_intc_init);
+
+static int __init
+ck_dual_intc_init(struct device_node *node, struct device_node *parent)
+{
+	int ret;
+
+	/* dual-apb-intc up to 128 irq sources*/
+	nr_irq = INTC_IRQS * 2;
+
+	ret = ck_intc_init(node, parent);
+	if (ret)
+		return ret;
+
+	/* Initial enable reg to disable all interrupts */
+	writel_relaxed(0, reg_base + CK_INTC_NEN31_00 + CK_INTC_DUAL_BASE);
+	writel_relaxed(0, reg_base + CK_INTC_NEN63_32 + CK_INTC_DUAL_BASE);
+
+	ck_set_gc(node, reg_base + CK_INTC_DUAL_BASE, CK_INTC_NEN31_00, 64);
+	ck_set_gc(node, reg_base + CK_INTC_DUAL_BASE, CK_INTC_NEN63_32, 96);
+
+	setup_irq_channel(0x00010203,
+			  reg_base + CK_INTC_SOURCE + CK_INTC_DUAL_BASE);
+
+	return 0;
+}
+IRQCHIP_DECLARE(ck_dual_intc, "csky,dual-apb-intc", ck_dual_intc_init);