riscv: Add a SYSCON driver for Andestech's PLIC

The Platform-Level Interrupt Controller (PLIC)
block holds memory-mapped claim and pending registers
associated with software interrupt. It is required
for handling IPI.

Signed-off-by: Rick Chen <rick@andestech.com>
Cc: Greentime Hu <greentime@andestech.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>

arch/riscv/Kconfig

@@ -109,6 +109,15 @@ config SIFIVE_CLINT
 	  The SiFive CLINT block holds memory-mapped control and status registers
 	  associated with software and timer interrupts.
 
+config ANDES_PLIC
+	bool
+	depends on RISCV_MMODE
+	select REGMAP
+	select SYSCON
+	help
+	  The Andes PLIC block holds memory-mapped claim and pending registers
+	  associated with software interrupt.
+
 config RISCV_RDTIME
 	bool
 	default y if RISCV_SMODE

arch/riscv/include/asm/global_data.h

@@ -18,6 +18,9 @@ struct arch_global_data {
 #ifdef CONFIG_SIFIVE_CLINT
 	void __iomem *clint;	/* clint base address */
 #endif
+#ifdef CONFIG_ANDES_PLIC
+	void __iomem *plic;	/* plic base address */
+#endif
 #ifdef CONFIG_SMP
 	struct ipi_data ipi[CONFIG_NR_CPUS];
 #endif

arch/riscv/include/asm/syscon.h

@@ -8,12 +8,11 @@
 
 /*
  * System controllers in a RISC-V system
- *
- * So far only SiFive's Core Local Interruptor (CLINT) is defined.
  */
 enum {
 	RISCV_NONE,
 	RISCV_SYSCON_CLINT,	/* Core Local Interruptor (CLINT) */
+	RISCV_SYSCON_PLIC,	/* Platform Level Interrupt Controller (PLIC) */
 };
 
 #endif /* _ASM_SYSCON_H */

arch/riscv/lib/Makefile

@@ -11,6 +11,7 @@ obj-$(CONFIG_CMD_GO) += boot.o
 obj-y	+= cache.o
 obj-$(CONFIG_RISCV_RDTIME) += rdtime.o
 obj-$(CONFIG_SIFIVE_CLINT) += sifive_clint.o
+obj-$(CONFIG_ANDES_PLIC) += andes_plic.o
 obj-y	+= interrupts.o
 obj-y	+= reset.o
 obj-$(CONFIG_SBI_IPI) += sbi_ipi.o

arch/riscv/lib/andes_plic.c

@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019, Rick Chen <rick@andestech.com>
+ *
+ * U-Boot syscon driver for Andes's Platform Level Interrupt Controller (PLIC).
+ * The PLIC block holds memory-mapped claim and pending registers
+ * associated with software interrupt.
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <dm/device-internal.h>
+#include <dm/lists.h>
+#include <dm/uclass-internal.h>
+#include <regmap.h>
+#include <syscon.h>
+#include <asm/io.h>
+#include <asm/syscon.h>
+#include <cpu.h>
+
+/* pending register */
+#define PENDING_REG(base, hart)	((ulong)(base) + 0x1000 + (hart) * 8)
+/* enable register */
+#define ENABLE_REG(base, hart)	((ulong)(base) + 0x2000 + (hart) * 0x80)
+/* claim register */
+#define CLAIM_REG(base, hart)	((ulong)(base) + 0x200004 + (hart) * 0x1000)
+
+#define ENABLE_HART_IPI         (0x80808080)
+#define SEND_IPI_TO_HART(hart)  (0x80 >> (hart))
+
+DECLARE_GLOBAL_DATA_PTR;
+static int init_plic(void);
+
+#define PLIC_BASE_GET(void)						\
+	do {								\
+		long *ret;						\
+									\
+		if (!gd->arch.plic) {					\
+			ret = syscon_get_first_range(RISCV_SYSCON_PLIC); \
+			if (IS_ERR(ret))				\
+				return PTR_ERR(ret);			\
+			gd->arch.plic = ret;				\
+			init_plic();					\
+		}							\
+	} while (0)
+
+static int enable_ipi(int harts)
+{
+	int i;
+	int en = ENABLE_HART_IPI;
+
+	for (i = 0; i < harts; i++) {
+		en = en >> i;
+		writel(en, (void __iomem *)ENABLE_REG(gd->arch.plic, i));
+	}
+
+	return 0;
+}
+
+static int init_plic(void)
+{
+	struct udevice *dev;
+	int ret;
+
+	ret = uclass_find_first_device(UCLASS_CPU, &dev);
+	if (ret)
+		return ret;
+
+	if (ret == 0 && dev) {
+		ret = cpu_get_count(dev);
+		if (ret < 0)
+			return ret;
+
+		enable_ipi(ret);
+		return 0;
+	}
+
+	return -ENODEV;
+}
+
+int riscv_send_ipi(int hart)
+{
+	PLIC_BASE_GET();
+
+	writel(SEND_IPI_TO_HART(hart),
+	       (void __iomem *)PENDING_REG(gd->arch.plic, gd->arch.boot_hart));
+
+	return 0;
+}
+
+int riscv_clear_ipi(int hart)
+{
+	u32 source_id;
+
+	PLIC_BASE_GET();
+
+	source_id = readl((void __iomem *)CLAIM_REG(gd->arch.plic, hart));
+	writel(source_id, (void __iomem *)CLAIM_REG(gd->arch.plic, hart));
+
+	return 0;
+}
+
+static const struct udevice_id andes_plic_ids[] = {
+	{ .compatible = "riscv,plic1", .data = RISCV_SYSCON_PLIC },
+	{ }
+};
+
+U_BOOT_DRIVER(andes_plic) = {
+	.name		= "andes_plic",
+	.id		= UCLASS_SYSCON,
+	.of_match	= andes_plic_ids,
+	.flags		= DM_FLAG_PRE_RELOC,
+};