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From: Christoph Hellwig <hch@lst.de>
To: Palmer Dabbelt <palmer@sifive.com>,
	Paul Walmsley <paul.walmsley@sifive.com>
Cc: Damien Le Moal <damien.lemoal@wdc.com>,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH 09/15] riscv: provide native clint access for M-mode
Date: Thu, 17 Oct 2019 19:37:37 +0200
Message-ID: <20191017173743.5430-10-hch@lst.de> (raw)
In-Reply-To: <20191017173743.5430-1-hch@lst.de>

RISC-V has the concept of a cpu level interrupt controller.  The
interface for it is split between a standardized part that is exposed
as bits in the mstatus/sstatus register and the mie/mip/sie/sip
CRS.  But the bit to actually trigger IPIs is not standardized and
just mentioned as implementable using MMIO.

Add support for IPIs using MMIO using the SiFive clint layout (which is
also shared by Ariane, Kendrye and the Qemu virt platform).  Additional
the MMIO block also support the time value and timer compare registers,
so they are also set up using the same OF node.  Support for other
layouts should also be relatively easy to add in the future.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/riscv/include/asm/clint.h | 39 ++++++++++++++++++++++++++++++
 arch/riscv/include/asm/sbi.h   |  2 ++
 arch/riscv/kernel/Makefile     |  1 +
 arch/riscv/kernel/clint.c      | 44 ++++++++++++++++++++++++++++++++++
 arch/riscv/kernel/setup.c      |  2 ++
 arch/riscv/kernel/smp.c        | 16 ++++++++++---
 arch/riscv/kernel/smpboot.c    |  4 ++++
 7 files changed, 105 insertions(+), 3 deletions(-)
 create mode 100644 arch/riscv/include/asm/clint.h
 create mode 100644 arch/riscv/kernel/clint.c

diff --git a/arch/riscv/include/asm/clint.h b/arch/riscv/include/asm/clint.h
new file mode 100644
index 000000000000..02a26b68f21d
--- /dev/null
+++ b/arch/riscv/include/asm/clint.h
@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef _ASM_CLINT_H
+#define _ASM_CLINT_H 1
+
+#include <linux/io.h>
+#include <linux/smp.h>
+
+#ifdef CONFIG_RISCV_M_MODE
+extern u32 __iomem *clint_ipi_base;
+
+void clint_init_boot_cpu(void);
+
+static inline void clint_send_ipi_single(unsigned long hartid)
+{
+	writel(1, clint_ipi_base + hartid);
+}
+
+static inline void clint_send_ipi_mask(const struct cpumask *hartid_mask)
+{
+	int hartid;
+
+	for_each_cpu(hartid, hartid_mask)
+		clint_send_ipi_single(hartid);
+}
+
+static inline void clint_clear_ipi(unsigned long hartid)
+{
+	writel(0, clint_ipi_base + hartid);
+}
+#else /* CONFIG_RISCV_M_MODE */
+#define clint_init_boot_cpu()	do { } while (0)
+
+/* stubs to for code is only reachable under IS_ENABLED(CONFIG_RISCV_M_MODE): */
+void clint_send_ipi_single(unsigned long hartid);
+void clint_send_ipi_mask(const struct cpumask *hartid_mask);
+void clint_clear_ipi(unsigned long hartid);
+#endif /* CONFIG_RISCV_M_MODE */
+
+#endif /* _ASM_CLINT_H */
diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index a4774bafe033..407d1024f9eb 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -97,6 +97,8 @@ static inline void sbi_remote_sfence_vma_asid(const unsigned long *hart_mask,
 #else /* CONFIG_RISCV_SBI */
 /* stubs to for code is only reachable under IS_ENABLED(CONFIG_RISCV_SBI): */
 void sbi_set_timer(uint64_t stime_value);
+void sbi_clear_ipi(void);
+void sbi_send_ipi(const unsigned long *hart_mask);
 void sbi_remote_fence_i(const unsigned long *hart_mask);
 #endif /* CONFIG_RISCV_SBI */
 #endif /* _ASM_RISCV_SBI_H */
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index d8c35fa93cc6..2dca51046899 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -29,6 +29,7 @@ obj-y	+= vdso.o
 obj-y	+= cacheinfo.o
 obj-y	+= vdso/
 
+obj-$(CONFIG_RISCV_M_MODE)	+= clint.o
 obj-$(CONFIG_FPU)		+= fpu.o
 obj-$(CONFIG_SMP)		+= smpboot.o
 obj-$(CONFIG_SMP)		+= smp.o
diff --git a/arch/riscv/kernel/clint.c b/arch/riscv/kernel/clint.c
new file mode 100644
index 000000000000..3647980d14c3
--- /dev/null
+++ b/arch/riscv/kernel/clint.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019 Christoph Hellwig.
+ */
+
+#include <linux/io.h>
+#include <linux/of_address.h>
+#include <linux/types.h>
+#include <asm/clint.h>
+#include <asm/csr.h>
+#include <asm/timex.h>
+#include <asm/smp.h>
+
+/*
+ * This is the layout used by the SiFive clint, which is also shared by the qemu
+ * virt platform, and the Kendryte KD210 at least.
+ */
+#define CLINT_IPI_OFF		0
+#define CLINT_TIME_CMP_OFF	0x4000
+#define CLINT_TIME_VAL_OFF	0xbff8
+
+u32 __iomem *clint_ipi_base;
+
+void clint_init_boot_cpu(void)
+{
+	struct device_node *np;
+	void __iomem *base;
+
+	np = of_find_compatible_node(NULL, NULL, "riscv,clint0");
+	if (!np) {
+		panic("clint not found");
+		return;
+	}
+
+	base = of_iomap(np, 0);
+	if (!base)
+		panic("could not map CLINT");
+
+	clint_ipi_base = base + CLINT_IPI_OFF;
+	riscv_time_cmp = base + CLINT_TIME_CMP_OFF;
+	riscv_time_val = base + CLINT_TIME_VAL_OFF;
+
+	clint_clear_ipi(boot_cpu_hartid);
+}
diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index a990a6cb184f..f4ba71b66c73 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -17,6 +17,7 @@
 #include <linux/sched/task.h>
 #include <linux/swiotlb.h>
 
+#include <asm/clint.h>
 #include <asm/setup.h>
 #include <asm/sections.h>
 #include <asm/pgtable.h>
@@ -65,6 +66,7 @@ void __init setup_arch(char **cmdline_p)
 	setup_bootmem();
 	paging_init();
 	unflatten_device_tree();
+	clint_init_boot_cpu();
 
 #ifdef CONFIG_SWIOTLB
 	swiotlb_init(1);
diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index b18cd6c8e8fb..c46df9c2e927 100644
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -14,6 +14,7 @@
 #include <linux/seq_file.h>
 #include <linux/delay.h>
 
+#include <asm/clint.h>
 #include <asm/sbi.h>
 #include <asm/tlbflush.h>
 #include <asm/cacheflush.h>
@@ -90,7 +91,10 @@ static void send_ipi_mask(const struct cpumask *mask, enum ipi_message_type op)
 	smp_mb__after_atomic();
 
 	riscv_cpuid_to_hartid_mask(mask, &hartid_mask);
-	sbi_send_ipi(cpumask_bits(&hartid_mask));
+	if (IS_ENABLED(CONFIG_RISCV_SBI))
+		sbi_send_ipi(cpumask_bits(&hartid_mask));
+	else
+		clint_send_ipi_mask(&hartid_mask);
 }
 
 static void send_ipi_single(int cpu, enum ipi_message_type op)
@@ -101,12 +105,18 @@ static void send_ipi_single(int cpu, enum ipi_message_type op)
 	set_bit(op, &ipi_data[cpu].bits);
 	smp_mb__after_atomic();
 
-	sbi_send_ipi(cpumask_bits(cpumask_of(hartid)));
+	if (IS_ENABLED(CONFIG_RISCV_SBI))
+		sbi_send_ipi(cpumask_bits(cpumask_of(hartid)));
+	else
+		clint_send_ipi_single(hartid);
 }
 
 static inline void clear_ipi(void)
 {
-	csr_clear(CSR_SIP, SIE_SSIE);
+	if (IS_ENABLED(CONFIG_RISCV_SBI))
+		csr_clear(CSR_SIP, SIE_SSIE);
+	else
+		clint_clear_ipi(cpuid_to_hartid_map(smp_processor_id()));
 }
 
 void riscv_software_interrupt(void)
diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index 18ae6da5115e..6300b09f1d1d 100644
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -24,6 +24,7 @@
 #include <linux/of.h>
 #include <linux/sched/task_stack.h>
 #include <linux/sched/mm.h>
+#include <asm/clint.h>
 #include <asm/irq.h>
 #include <asm/mmu_context.h>
 #include <asm/tlbflush.h>
@@ -134,6 +135,9 @@ asmlinkage void __init smp_callin(void)
 {
 	struct mm_struct *mm = &init_mm;
 
+	if (!IS_ENABLED(CONFIG_RISCV_SBI))
+		clint_clear_ipi(cpuid_to_hartid_map(smp_processor_id()));
+
 	/* All kernel threads share the same mm context.  */
 	mmgrab(mm);
 	current->active_mm = mm;
-- 
2.20.1


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  parent reply index

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-17 17:37 RISC-V nommu support v5 Christoph Hellwig
2019-10-17 17:37 ` [PATCH 01/15] riscv: cleanup <asm/bug.h> Christoph Hellwig
2019-10-18  2:50   ` Anup Patel
2019-10-23 22:04   ` Paul Walmsley
2019-10-17 17:37 ` [PATCH 02/15] riscv: cleanup do_trap_break Christoph Hellwig
2019-10-18  2:51   ` Anup Patel
2019-10-23 22:05   ` Paul Walmsley
2019-10-17 17:37 ` [PATCH 03/15] riscv: abstract out CSR names for supervisor vs machine mode Christoph Hellwig
2019-10-18  2:51   ` Anup Patel
2019-10-18 23:55   ` Paul Walmsley
2019-10-28  8:12     ` Christoph Hellwig
2019-10-17 17:37 ` [PATCH 04/15] riscv: don't allow selecting SBI based drivers for M-mode Christoph Hellwig
2019-10-18  2:52   ` Anup Patel
2019-10-17 17:37 ` [PATCH 05/15] riscv: poison SBI calls " Christoph Hellwig
2019-10-18  2:53   ` Anup Patel
2019-10-17 17:37 ` [PATCH 06/15] riscv: cleanup the default power off implementation Christoph Hellwig
2019-10-18  2:53   ` Anup Patel
2019-10-17 17:37 ` [PATCH 07/15] riscv: implement remote sfence.i using IPIs Christoph Hellwig
2019-10-18  2:55   ` Anup Patel
2019-10-17 17:37 ` [PATCH 08/15] riscv: add support for MMIO access to the timer registers Christoph Hellwig
2019-10-18  2:57   ` Anup Patel
2019-10-17 17:37 ` Christoph Hellwig [this message]
2019-10-18  3:00   ` [PATCH 09/15] riscv: provide native clint access for M-mode Anup Patel
2019-11-14  7:39   ` Paul Walmsley
2019-10-17 17:37 ` [PATCH 10/15] riscv: read the hart ID from mhartid on boot Christoph Hellwig
2019-10-18  3:01   ` Anup Patel
2019-11-14  7:40   ` Paul Walmsley
2019-10-17 17:37 ` [PATCH 11/15] riscv: use the correct interrupt levels for M-mode Christoph Hellwig
2019-10-18  3:01   ` Anup Patel
2019-10-17 17:37 ` [PATCH 12/15] riscv: clear the instruction cache and all registers when booting Christoph Hellwig
2019-10-18  3:05   ` Anup Patel
2019-10-17 17:37 ` [PATCH 13/15] riscv: add nommu support Christoph Hellwig
2019-10-18  3:04   ` Anup Patel
2019-10-17 17:37 ` [PATCH 14/15] riscv: provide a flat image loader Christoph Hellwig
2019-10-18  3:06   ` Anup Patel
2019-10-17 17:37 ` [PATCH 15/15] riscv: disable the EFI PECOFF header for M-mode Christoph Hellwig
2019-10-18  3:06   ` Anup Patel
2019-10-18  3:08 ` RISC-V nommu support v5 Anup Patel
2019-10-18  3:29   ` Paul Walmsley
2019-10-18 15:25     ` Christoph Hellwig
2019-10-18 23:46       ` Paul Walmsley

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